Gil Nonato Santos
Dr. Prof. Gil Nonato C. Santos is a Full Professor and Vice Chancellor for DLSU Laguna Campus. He has an undergraduate and graduate degree in Physics at De La Salle University and University of the Philippines and a Doctorate degree in Materials Science and Engineering at the University of the Philippines Diliman National Institute of Physics. He is a Research Fellow at the University of Fukui doing research of nanocomposite materials and its terahertz applications, and Visiting Professor in Osaka University Quantum Engineering Laboratory and at Howard University's Atmospheric Science Research Laboratory . He is the Research Head of the Solid State Physics Laboratory, Inanolab research facility, and has published local and international publications in Nanomaterials. He has a patent work for growing nanomaterials called the horizontal vapor phase growth (HVPG) technique. He is the Convenor of Philippine Association of Physics and Science Instructors and was awarded Most Outstanding Physics Educator in 2010 by the Philippine Physics Society. In 2012, he was a recipient of the Challenge Grant for establishing an Air Weather Observation System for De La Salle Philippines and Volunteer Schools called SIGWA (Students Involve in Geophysical Weather and Atmospheric studies) and an AKI grant for developing a nanosensor for detecting meat spoilage. He also obtained a research grant from DOST for developing Tin Oxide Silver Nanocomposite materials for antiheat and antibacterial applications, a US Aid Carwin Grant for developing nanocomposite materials for anticorrosion and antibarnacle applications for ship hull and development of a nanosensor for detecting lung diseases, and a CHED DARETO Grant for developing a nanosensor for animal feeds.
Phone: (049)554-8900 (Trunk Line)
Address: De La Salle University Science and Technology Complex
Laguna Boulevard, LTI Spine Road, Barangays Biñan and Malamig, Biñan City, Laguna
Phone: (049)554-8900 (Trunk Line)
Address: De La Salle University Science and Technology Complex
Laguna Boulevard, LTI Spine Road, Barangays Biñan and Malamig, Biñan City, Laguna
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Books by Gil Nonato Santos
Provides the learners relevant experiences in their performance of independent experimentation and tasks that are significant to the society; thus concepts learned are tailored for life application
Lesson trivia pops up within the lesson presentation to keep the mind of the students hooked in the lesson
Papers by Gil Nonato Santos
Provides the learners relevant experiences in their performance of independent experimentation and tasks that are significant to the society; thus concepts learned are tailored for life application
Lesson trivia pops up within the lesson presentation to keep the mind of the students hooked in the lesson
syllabus and eight (8) TL topics that consist of the following: Introduction to physics of materials, Physical quantities and Unit of Measurements, Introduction in the study of
materials, Thermal property of materials, Electrical and magnetic property of materials, Mechanical property of materials, Optical property of materials, and Deteriorative
property of materials. Each topic includes the following: objectives, materials and equipment, student ideas about the topic, key concept points for understanding, procedure,
activities, processing questions, output, and assessment. The arrangement of the topics will aid the Instructor in teaching SCIMATP.
syllabus and eight (8) TL topics that consist of the following: Introduction to physics of materials, Physical quantities and Unit of Measurements, Introduction in the study of
materials, Thermal property of materials, Electrical and magnetic property of materials, Mechanical property of materials, Optical property of materials, and Deteriorative
property of materials. Each topic includes the following: objectives, materials and equipment, student ideas about the topic, key concept points for understanding, procedure,
activities, processing questions, output, and assessment. The arrangement of the topics will aid the Instructor in teaching SCIMATP.
1Physics Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
2Electronics and Communications Engineering Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
*Corresponding author: [email protected]
ABSTRACT: Galvanostatic and galvanodynamic methods of electrochemical deposition were employed to fabricate conducting polypyrrole (PPy) film electrodes for supercapacitor applications. In this method, zinc oxide- and sodium p-toluenesulfonate- doped film electrodes were electrochemically synthesized in an aqueous solution containing 0.10M pyrrole as monomer and 0.12M sodium p-toluenesulfonate (Na-pTS) as dopant and 0.1M zinc oxide (ZnO) as co-dopant. A two-electrode electrochemical cell was used, and for counter and working electrodes, stainless-steel plates. The applied current density during synthesis was kept at 4mA/cm2 with varying duty cycle of 25%, 50%, 75% and 100%, respectively. The thickness and surface morphology of the Zno/NapTS/PPy films grown were obtained using scanning electron microscopy. The ZnO/NapTS/PPy films have average thickness ranging from 30.60 μm to 1688.0 μm. The surface morphology of ZnO/NapTS/PPy film synthesized at constant current (100% duty cycle) exhibits lamellar and spherulite structures associated with increased conductivity. The measured AC resistance of the ZnO/NapTS/ PPy films ranged from 0.64 Ω to 3.9 Ω, with the films synthesized at 100% duty cycle showing the lowest AC resistance.
Key words: supercapacitor, conducting polymers, polypyrrole
1Physics Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
*Corresponding author: [email protected]
ABSTRACT: A certain amount of time after the implementation of intervention to control an outbreak, a kink develops in the epidemic curve. These discontinuities in the gradient of the curve should be treated as observables as they confirm the effectiveness of interventions that began in the past. As a retarded response time of an epidemic to intervention, this may be used to parametrize the effectiveness of the intervention in flattening the curve. To construct a model that recognizes how this kink heralds the flattening of the curve, we draw upon the qualitative features of the S-ℑ-ℜ model, but in recognition of the role of the kink, we forego smoothness of the curve at this transitional stage. With these in mind, we formulate an analytic expression for the fraction of the population infected by a contagious disease spreading according to some power law, and responsive to a delayed intervention. Up to the time when the effect of the intervention manifests, instead of using the conventional exponentially increasing function known to over-estimate the data, the outbreak is modeled by a real power function which more closely describes the accelerated stage of epidemics. The moment the intervention takes effect, a decaying exponential function with a characteristic time defined by the viral power and the time of the appearance of the kink is introduced to flatten the power curve. The model provides a calculation for the peak of the epidemic as well as the inflection times when rate of change in the number of infectives is extremum. The recent Philippine May 23, 2020 data on COVID-19 pandemic is used in sample calculations.
Key words: epidemiology, epidemic curve, exponential growth and decay, sub-exponential growth, power function, S-ℑ-ℜ model, gamma/factorial function, binomial expansion, critical points, stationary points, curvature, concavity, inflection points, kink, COVID-19, incubation period, recovery period, social/physical distancing, community quarantines
1Physics Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
2University of Santo Tomas España Blvd, Sampaloc, Manila Philippines
3Research Management Division, Commission on Higher Education, Philippines;
Technological Institute of the Philippines, Cubao, Quezon City, Philippines
*Corresponding author: [email protected]
ABSTRACT:
The study investigated the effect Zinc Oxide nanoparticle structures on the toxicity and teratogenicity towards zebrafish. Varying structures of Nano-Zinc Oxide crystals were synthesized at sizes similar to commercially available 50 nm to 100 nm particles and exposed to zebrafish embryo for a span of 5 days conducting toxicity and teratogenicity assay. While previous studies debated the result of commercially available Zinc Oxide nanoparticles, the synthesized Nano-Zinc Oxide demonstrated definite toxicity. An interesting finding showed that at higher concentration the zebra fish were eradicated at an early stage of the experiment but lower concentration created higher mortality rate in the end.
Key words: zinc oxide, nanomaterials, HVPG, toxicity test, teratogenicity
1Physics Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
*Corresponding author: [email protected]
ABSTRACT: In this study, the respiratory quotient (RQ) and respiration rate (RR) of Lakatan [Musa acuminata (AAA group)] bananas were obtained for 14 days using a flow-through system under three environmental conditions; in particular, non-airconditioned, airconditioned, and refrigerated with corresponding temperatures of 33°C ± 2°, 24°C ± 2°, and 7°C ± 2°, respectively. The Lakatan bananas were enclosed in glass gas-tight chambers and the carbon dioxide CO2 and oxygen O2 concentrations in the chambers were measured daily for 14 data. From the measured CO2 and O2 concentrations, values of RQ and RR were calculated. Results show that CO2 concentrations generally increased during the ripening stage, from day 1 to 4, then decreased over time. Highest CO2 variations, ranging from ~0.45 to ~0.83, were observed in bananas kept at 33°C ± 2°; while CO2 variations were minimal for those stored at 24°C ± 2°. The O2 concentrations were fairly constant over 14 days. Further, the O2 concentrations measured from bananas kept at 7°C ± 2° were higher than those kept at 33°C ± 2°. The RQ values were found to decrease over time under all three temperature conditions. All the RQ values were less than one, which implies that lipid was the main metabolic substrate being oxidized all throughout the 14 days. It was also observed that the RQ values remain almost constant from day 7 to 14, and were higher, by as much as 13.1%, in bananas kept at 33°C ± 2° as compared to those at 7°C ± 2°. Results show that storage temperature is a major factor in measured RQ values. Measurement of RQ and RR these values could be used to determine the stage of fruit development and determine the optimum conditions to prolong the shelf-life of fruits.
Key words: Respiration Rate, Respiratory Quotient, Lakatan bananas
1Physics Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
*Corresponding author: [email protected]
ABSTRACT: Glucose is a constituent of blood amongst humans and is the primary source of nearly all the energy in the cells and organs of the body. It is formed after the consumption of sustenance in which it is abundant in sugar levels. Glucose undergoes the process of glycolysis in order to oxidize and form adenosine triphosphate (ATP) molecules which provide our body the energy for cellular activities. Thus, having sufficient glucose in the blood is critical to a human’s well-being. On the other hand, an excessive amount of glucose in the blood can lead to serious complications such as diabetes, a disease that damages the body’s ability to process glucose in the blood and is the major cause of organ failures. Patients diagnosed with diabetes are advised to monitor their glucose levels using a portable electronic glucose meter which makes use of the invasive finger-prick method. However, this method is inconvenient for most patients because of its painful and distressing invasive process as this is repeated frequently. In response to a need for a less painful and convenient method for detecting blood sugar level, the authors report a non-invasive alternative method to blood glucose monitoring based on human breath analysis. Data and correlation studies show moderate correlation between breath CO2 concentration and blood glucose level, indicating that breath CO2 concentration can be used as a biomarker for blood sugar levels.
Key words: glucose, diabetes, carbon dioxide, non-invasive glucose monitoring, breath analysis
1 Chemistry Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
2 Department of Sociology, University of the Philippines, Diliman, Quezon City, Philippines
*Corresponding [email protected]
ABSTRACT:
Existing studies often treat pottery as a determinant of sociocultural integrity and technical proficiency. It is assumed that the aesthetic design, ceramic style and clay contour of pottery are coherent to material culture definition. As an illustration, Philippine pottery artefacts reflect the coming together of sociocultural, material and technical components. Philippine pottery artefacts were evidenced in different diggings in Pila, Laguna since 1967. Identities of the Philippine artefacts dated from the 12th to the 15th centuries from the Chinese merchants using the Manila-Laguna Bay trading route. From one of the diggings in a private property in Baranggay Pinagbayanan, Pila (Laguna), random samples were gathered, verified and chemically analyze as representatives. Integrated complementary-parallel study (cultural-historical profiling and chemical characterization) on the pottery are used but distinct on the basis of approaches. Profile of the historical pottery from Pila, Laguna was interpreted using secondary source data to organize information. The analytical techniques used in this study were Fourier Transform Infrared (FTIR) spectroscopy and X-ray fluorescence (XRF). The analytical result of sample fragment PPL1, PPL2 and PPL3 were silicon: 64.38 %, 52.07 % and 66.34 % as well as aluminum: 17.76 %, 17.14 % and 16.82 % as major components respectively. Fluxes used were iron: 5.26 %, 18.04 % and 4.65 %, calcium: 1.83 %, 4.64 % and 1.25 % as well as potassium: 8.35%, 2.76 % and 9.30 % respectively. There were elemental traces used as colorants namely: iridium (Ir), manganese (Mn), titanium (Ti), strontium (Sr), lead (Pb) and zinc (Zn). IR spectroscopy of the pottery samples showed approximate peaks assigned to quartz, alumina, calcite, hematite and magnetite.
Key words: Pottery, Fourier-Transform Infrared (FT-IR), Energy Dispersive X-Ray Fluorescence (ED-XRF), silica, alumina, material characterization
1 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
2 Physics Department, Central Mindanao University, Maramag Bukidnon 8710, Philippines
3 Kotel’nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Russia
*Corresponding author: [email protected]
ABSTRACT: Abstract
Metal oxide nanomaterials from zinc oxide bulk powder and tin (II) oxide bulk powder were synthesized via Horizontal Vapor Phase Crystal Growth deposition technique. Fabricated nanocrystals were successfully deposited on a silica quartz tube and were used as the sensing element of a fabricated gas sensor. Both zinc oxide and tin oxide showed nanowire structures. This indicated a high surface-to-volume ratio which favors the adsorption of gases on the sensing element which increases the sensitivity of the device.
Key words: Zinc Oxide Nanomaterials, Tin Oxide Nanomaterials, HVPG
1 Philippine Science High School – Central Luzon Campus, Lily Hill St., Clark Freeport Zone, Pampanga, Philippines
*Corresponding author: [email protected]
ABSTRACT: Cuprous oxide dye-sensitized solar cells (DSSCs) were fabricated through the use of chlorophyll from malunggay leaves (Moringa oleifera) as sensitizers. UV- Visible spectroscopy results indicated the presence of chlorophyll in malunggay leaves. Four set-ups, each with replicates, were made: one with no pigment and three with cuprous oxide submerged in the pigment for 24, 48, and 72 hours, respectively. The measured voltage outputs of the DSSCs show that as the time of submersion of the cuprous oxide on the pigment increases, the voltage output produced also increases. In terms of efficiency testing, it was found that the solar cells with chlorophyll-soaked cuprous oxide had a lower efficiency than those with cuprous oxide not soaked in chlorophyll pigment.
Key words: Solar cells, cuprous oxide, chlorophyll, Moringa oleifera
1 Chemistry Department, College of Science, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: Abstract
The study focused on the metathesis reaction of bis(triphenylphosphine) iminium chloride (PNPCl) with sodium bromide (NaBr) which yielded bis(triphenylphosphine) iminium bromide (PNPBr). The cation from the product which is bis(triphenylphosphine) iminium (PNP) serves as a counter ion for molecular conductors to ease electron transport between anions thus aiding in the formation of a regular stacked arrangement of conductors in a solid state. PNPBr was validated by the bromine presence determined by the Halogen Test using sulfuric acid, by comparing the experimental value of the melting point of the product to its theoretical value, and by the elemental composition of the sample in which the elements determined were carbon, nitrogen, bromine, and phosphorus only. Therefore, through these tests the product has a high purity and has a percent yield of 81.56%.
Key words: bis(triphenylphosphine) iminium chloride, bis(triphenylphosphine) iminium bromide, bis(triphenylphosphine) iminium
1 Industrial Technology Development Institute, Department of Science and Technology, General Santos Avenue, Bicutan, Taguig City, Philippines
2 Chemistry Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: Abstract
Labelling of trans fatty acid (TFA) content in foods is mandatory in many countries and being considered in several countries because of the deleterious effect of trans fatty in health and nutrition of the individual. The impact of legislation restricting use of TFA in food products and requiring TFA content on food labels prompts analytical laboratories to address outstanding issues on trans fatty acid analysis. In this work, a molecularly imprinted polymer (MIP) using trans oleic fatty acid methyl ester as template has been prepared by precipitation polymerization method using methacrylic acid as functional monomer, trimethylolpropane methacrylate (TRIM) as cross-linking agent, 2,2-azobis (isobutyronitrile) as the radical initiator and dichloromethane as porogen. This trans-MIP was used as sorbent for the solid-phase extraction of trans oleic fatty acid before injection to the gas chromatograph for quantification. A non-imprinted polymer (NIP) was also prepared using the same procedure but without the addition of the template, trans oleic fame. Template removal was done by soxhlet extraction using methanol-acetic acid (9:1 v/v) as the extraction solvent.
The binding properties of trans oleic fame imprinted polymers were evaluated in different solvent system by equilibrium experiments. A higher difference between the affinity of trans oleic fame to MIP and NIP in heptane and dichloromethane was observed. Scatchard plot’s analysis revealed that there were two classes of binding sites populated in the imprinted polymers which indicated that the polymer possesses a heterogeneous binding sites distribution. The stronger affinity binding type exhibits dissociation constant (Kd) 10 times smaller than that of the weaker type with binding capacity of 48.04 ug trans oleic fame/mg MIP. The resulting Freundlich isotherm further demonstrated the heterogeneity of the binding sites of the MIP, with heterogeneity index “a” equal 0.4758 which is less than 1.
The imprinting effect of the MIP was assessed by its performance as sorbent in SPE experiment by varying the solvent type, time, amount of sorbent and amount of trans oleic fame to obtain acceptable recoveries in each step of the solid-phase extraction. Recoveries in trans-MIP was higher (79.9-87.4%) using methanol-acetic acid as the eluting solvent compared to NIP (55.8-68.7%).
Polymer characterization was done by scanning electron microscopy and particle size analyzer for its morphology and particle size distribution, respectively.
Elemental and FTIR analysis of the synthesized MIP was also done and results showed that the polymerization method was successful.
Key words: Trans Oleic Fatty Acids, non-imprinted polymer, FTIR
1 De La Salle University Integrated School, Biñan, Laguna, Philippines
2 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: This paper seeks to find a way to measure blood glucose levels in real time, in-situ, non-invasively, painlessly, and cost-effectively using matched LED pairs as photo-transmitter and photo-detector. The research demonstrated the feasibility of using the same high-intensity, narrow-beam transmitter LED as photo-detector, improving selectivity and sensitivity. Using a near- infrared LED (GaAlAs, 895 nm, 20mW, 8˚ half-power beam width), the following relationship between signal attenuation at the detector versus the glucose concentration in solution was obtained:
𝐺𝑙𝑢𝑐𝑜𝑠𝑒 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 = 0.004(NIR LED output Voltage) + 9.2707 with a very high Pearson’s Correlation Coefficient of +0.9985 and a coefficient of determination of 0.9971, highly correlated and highly linear.
Key words: Non-invasive blood glucometer, LED-based glucometer
1 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: Abstract
We investigated the anticorrosive, hydrophobic and anti-barnacle properties of polyaniline and graphene (PANI/G) nanocomposite filler in the coating matrix applied to ship hulls. Various formulations of graphene were integrated to polyaniline matrix through in situ polymerization. It was observed that the 0.5%, 1.0%, and 2.5% by weight graphene formulation performed better than the counterparts with higher amount of graphene content as barrier protection. The various coating formulations were applied directly to the metal coupons. It was also observed that the PANI/G nanocomposite exhibited a hydrophilic property. The addition of polysiloxane to the mixture resulted in a hydrophobic surface with a contact angle of 108 degrees. Results show the absence of barnacle growth on metal samples coated with PANI/G/polysiloxane formulation. It is proposed that this anti-barnacle property is due to the hydrophobicity of the surface.
Key words: PANI, graphene, polysiloxane, HVPG,
1 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: A brief account of self-similarity manifest in certain physical phenomena is presented. In particular, the quantum harmonic oscillator is shown to be representable in terms of a self-similar matrix that contains the golden ratio as a special case.
Key words: Fibonacci sequence, golden ratio, self-similarity, scale invariance, conformal geometry, conformal cyclic cosmology, harmonic oscillator, ladder operators, creation and annihilation operators, Heisenberg uncertainty principle, Fock space, coherent states
1 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: As worldwide energy demands increase; new sources of renewable energy must be found. Thermoelectric generators have the potential to harness the vast amounts of waste heat coming off current machines, electronics, and infrastructure. In this study, conducting polypyrrole (PPy) doped with Na p-toluenesulfonate (Na-pTs) and hydroquinone sulfonic acid potassium salt (𝐶6𝐻3𝑆𝑂3𝐾) were electrochemically deposited on Indium-Tin-Oxide (ITO) glass slides at various duty cycles. Positive Seebeck coefficients were measured from all PPy(Na-pTs) /ITO structures, and on PPy(𝐶6𝐻3𝑆𝑂3𝐾)/ITO structures synthesized at 20% and 40% duty cycles. Seebeck coefficients ranging from -4.45 to 29.0mV/K were obtained. The Ppy(Na-pTs)/ITO structures exhibited higher Seebeck coefficients and open-circuit voltages than the PPy(𝐶6𝐻3𝑆𝑂3𝐾)/ITO structures.
Keywords: physical systems, polymers, conducting polymers, Seebeck effect
1 De La Salle University-Manila, Solid State Physics Laboratory, 2401 Taft Ave. Manila, 1004 Philippines
2 Department of Mining, Metallurgical and Materials Engineering, University of the Philippines, Diliman, Quezon City, Philippines
*Corresponding author: [email protected]
ABSTRACT: Abstract
The Philippine natural zeolites (PNZ) were doped with zinc using ion exchange process. Calcined and un-calcined samples of zinc oxide-zeolite (ZnO-PNZ) composites were characterized by using Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The FTIR spectrum showed the characteristic peaks and structure of PNZ upon the incorporation of zinc oxide (ZnO). On one hand, SEM analysis confirms the formation of ZnO nanoparticles on the surface of zeolite. The calcination procedure did not alter the crystalline structure of the ZnO-PNZ composite.
Keywords: zeolite, zinc-zeolite, FTIR, ion exchange
Physics Department, De La Salle University,
2401 Taft Avenue, Manila, Philippines
[email protected]
ABSTRACT: Newton’s mathematical description of motion using the basic concepts of differential calculus is briefly revisited and applied. The concept of the derivative and Taylor’s theorem are used to categorize the simplest types of motion. The mathematical description of harmonic motion and wave propagation equation is also discussed.
Key words: kinematics, dynamics, derivative, displacement, velocity, acceleration, jolt, jerk, jounce, snap
1 Victorino Mapa High School, 300 San Rafael St. San Miguel, Manila,Philippines
2 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: Electrical energy demand and sludge sanitation problems grow rapidly. While sludge treatment requires a huge amount of electricity, sludge itself may be utilized to harness a lot of energy. This study determined the potential of Diesel Exhaust Particles (DEPs) and Zeolite as anode and cathode, respectively, to generate a voltage in Microbial Fuel Cell (MFC) and identify the organisms that were present on the electrodes.
DEP and Zeolite were collected and pulverized into fine powder. DEP (330mg) and Zeolite (330mg) were pasted on 2.5cmx3cm steel mesh using 1mL nail polish. Morphologies of the electrodes were examined using Jeol, JSM- v45310 SEM and elemental compositions were determined using EDX. MFCs with sludge and tap water as substrates for anode and cathode, respectively, and were measured individually for voltage production using a multitester. Bacteria present on the electrode were isolated and identified phenotypically up to genus level. SEM and EDX results showed DEP has a nanospherical structure with an average particle size of 57.28nm, which increases the voltage generation by increasing the surface area, DEP is composed of 39.73% C while Zeolite has Al and Si which indicates the adsorption capability of Zeolite. Voltage outputs of the MFCs for 24h were calculated by area under the curve: Mesh- Mesh (6,480mVh), Mesh-Zeolite (5,895mVh), DEP-Mesh (8,082mVh),DEP-Zeolite (8,022mVh) and DEP-Zeolite (tap water-52.46mVh). The second setup was made using DEP-Z and was observed for 24h which produced a total power of 294.24 mWh. Isolated and characterized Pseudomonas spp. and Aeromonas spp. from the surface of the electrodes in the MFCs possibly contributed to voltage generation.
DEP is a bio-compatible anode to Aeromonas spp. and Pseudomonas spp. while an adsorptive Zeolite as a cathode enhances voltage production. Hence, DEP and Zeolite can be fabricated as a biocompatible anode and adsorptive zeolite for low-cost MFC technology.
Key words: Microbial Fuel Cells, Diesel Exhaust Particles, Zeolite, Aeromonas spp., Pseudomonas spp
1 Victorino Mapa High School, 300 San Rafael St. San Miguel, Manila, Philippines
2 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: In this study, chitin and N/Mn-doped carbon nanostructures were fabricated and characterized for thin film solar cell (TFSC) applications. Chitin, which has high heat resistivity and UV-Vis absorption peak of 250-750nm (Azofeifa, et al., 2012), was transformed into nanomaterials. These were combined with carbon nanostructures (CNS), which are known for high efficiency in solar cells.
Chitin from local crab shells was extracted by deproteinization, demineralization and decolorization. Chitin and N/Mn-doped carbon were fabricated into nanomaterials via Horizontal Vapor Phase Growth Technique (Santos, et al., 2009). Their morphology was determined using SEM imaging software, and their elemental and atomic compositions by EDX Oxford Spectroscopy. Photoconductivity was measured with and without solar illumination using fluke multimeter. The efficiency was calculated based on η = (Pmax/E x AC) x100.
The surface morphology of chitin was observed to be nanowires with physical size of 45nm while N/Mn-doped CNS was observed to be nanoflakes and measured at 84.6nm (N) and 92.73nm (Mn), respectively. Chitin contained 31.55% nitrogen; N-CNS, 31.73% nitrogen and Mn-CNS, 2.13% manganese. I-V characteristics yielded short-circuit current of 0.08mA, open-circuit voltage of 120.1mV, maximum power of 9.61mW and efficiency as high as 16.02%. Chitin nanowires increased the TFSC’s efficiency by 6.69% due to its high photoelectric properties.
The results showed that chitin nanowires and N/Mn-CNS comprise a promising TFSC that uses an abundant biopolymer and an innovative technique for green production of electrical energy. Organic–inorganic solar thin films with efficiencies up to 9% are practicable devices for sustainable development and energy crisis.
Key words: Crab Shells, Chitin Nanowires, Carbon Nanostructures, Thin Film Solar Cell
Luzviminda A. Dinglasan1,*, Gil Nonato C. Santos2
1 Victorino Mapa High School, 300 San Rafael St. San Miguel, Manila, Philippines
2 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: Fruit fly oviposition on the mango resulted to brown and black spots causing the non-marketability of the mangoes and economic loss to the growers while 90-96% of the CaCO3 present in the eggshells is disposed as waste. Hence, this study was conducted to assess the farmers’ perception on the occurrence and economic impact of B. philippinensis and determine its ovipositional behavior when applied by nano-CaCO3 from chicken eggshells.
Semi-structured questionnaire was surveyed to 32 mango growers in Pangasinan to assess the economic impact of the flies. Nano-CaCO3 was synthesized from eggshells by mixing the 50g powder to 350 mL NaOH 1 N, stirring on hot plate for 1h at 1000C. SEM and FTIR were used to determine the morphology, size and functional groups of the nano-CaCO3. Ovipositional behavior of B. philippinensis was prepared using 5 setups of distilled water (mL) and nano-CaCO3 (g); A 100mL:0.625g, B 100mL:1.25g, C 100mL:5g, D 100mL:10g and E 100mL (0g-control). Ovicidal effect was determined by getting the mean amount of the mortality rate of pupa and larvae developed in the mango.
Ninety six percent (96.88%) of the mango growers strongly agreed that fly reduces growers' income and 3.13% agreed. SEM showed that nano-CaCO3 has an average size of 135 NM and bulk like structure while FTIR confirmed CaCO3 group at 875.11cm-1. Ovicidal activity was found 0% pupa emergence at 0.625g and 10g nano-CaCO3 while 2.11% pupa emergence in control. Mortality rates of larvae were 82.48% and 62% at 1.25g and 5g nano-CaCO3 while zero (0%) dead larvae in control.
Late development of B. philippinensis larvae was caused by nano-CaCO3. Hence, CaCO3 from eggshells can be explored by the agriculturists as alternative bio-insecticides for vast crop production, pest management and economic income development.
Key words: Calcium carbonate nanoparticles, Bactrocera philippinensis, ovicidal effect, chicken eggshells, insecticide, nanomaterial, agriculture
1 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
2 Physics Department, Technological University of the Philippines, Manila, Philippines
*Corresponding author: [email protected], [email protected]
ABSTRACT: In this research, graphene oxide and carbon nanomaterials were fabricated and characterized using Horizontal Vapor Phase Growth (HVPG) Technique. The nanostructures formed by the technique were deposited on a glass substrate using carbon nanopowder and on the walls of the quartz tube using the graphene nanopowder as bulk material. The growth temperature ranged from 600°C to 1200°C, growth time ranged from 4 to 8 hours and the dwell time being held constant at 60 minutes.
The surface topography, morphology and elemental composition of the synthesized nanomaterial were investigated through scanning electron microscope (SEM) and Energy dispersive X-ray (EDX). The photoluminescent characteristic and resistivity were investigated using Spectral microscope and van der Pauw method respectively. The nanostructure formed were nanosheets, nanofibers, nanowires and isolated nanocubes. The characteristic emission peak in the photoluminescence spectra was observed at around 350 nm for the growth temperature of 1200°C for 8 hours growth time and presented a strong peak at 721.23 nm. The characteristic emission peak was also at around 325 nm but the second peak was only at 395.44 nm for the same growth temperature but for 6 hours growth time. The resistivity of the grown nanomaterial using the carbon and graphene nanopowder was investigated. The nearest value of resistivity was 2.3 x 10^-4 Ω m that falls near to that of amorphous carbon which is 5x10^-4 – 8x10^-4 Ω m.
Key words: nanoparticles, graphene oxide, carbon nanomaterials, photoluminescence, resistivity
1 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: A 12V solar-powered hydroponics system which auto-regulates its pH was designed and fabricated. The pH can be pre-set to any range and is continuously monitored by a pH probe which is connected to an Arduino-based microcontroller. Deviations from the pre-set pH range were successfully auto-regulated by the microcontroller that controlled two peristaltic pumps containing maximum pH and minimum pH solutions. The solution with a pH of 1.10 provides the optimum growth performance. A test involving live seedlings further confirmed the viability of running the hydroponic system solely on solar-generated power.
Key words: hydroponics, microcontrollers, peristaltic pumps
1 Chemical Engineering Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
2 Chemical Engineering Department, Pamantasan ng Lungsod ng Maynila, Intramuros, Manila, Philippines
3 Chemistry Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
4 Civil Engineering Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding author: [email protected]
(Presented at the 2016 Seminar Workshop on the Utilization of Waste Materials)
ABSTRACT: This research focus on the chemical and toxicity characterization of coal ash from coal dust fired gravity circulation boiler. The objective of the study is to determine the toxicity of the coal ash and its application as a geopolymer raw material. In this study, coal ash samples were collected from both the silo and ash pond. Results from X-ray diffraction analysis (XRD) of this ash indicate major ferro-, alumino-, and silicate minerals such as quartz-SiO2, lime-CaO, tricalcium aluminate, and magnetite. Moreover, X-ray Fluorescence analysis (XRF) confirms the presence of such major elements such as silicon, aluminum, calcium and iron. Results from XRD and XRF suggest the presence of amorphous silica and alumina which are important precursor to produce a geopolymer-based material. In addition, the fly ash can be classified as moderate calcium content-fly ash which may exhibit both pozzolanic and cementious properties. However, the sulfur content is relatively high to meet the requirement of class C or F fly ash according to ASTM specification. Leachability analysis of the coal ash sampled from ash pond was also performed based on Toxicity Characteristics Leaching Procedure (TCLP). TCLP results indicate that the leachate concentration of toxic metals such as arsenic, cadmium, chromium, lead, and mercury from the coal ash disposed in the ash pond were below the permissible limit set by environmental regulatory agency. Thus, the coal ash can be classified as non-hazardous based on this regulatory leaching test.
Key words: coal ash, characterization, TCLP, geopolymer
De La Salle University, 2401 Taft Avenue, Malate, Manila, Philippines
Presented at the Philippine Economic Zone Authority (PEZA) From Paris Agreement to PEZA Commitment: Promoting a UNFCCC-Conscious Ecozone Development Planning in celebration of the World Environment Day on 5th and 6th day of June, 2017 at the PEZA Social Hall of the PEZA Head Office, Bonifacio Global City 1634 Metro Manila, Philippines
ABSTRACT: This review aims to provide a broader perspective to the current interest on climate variability by revisiting the astrophysical mechanisms that dictate our planet’s climate cycles. The intrinsic variability of the sun’s power output is indisputably a dominant contributor to global temperature as its irradiance pulsates roughly every ~10.7 years, modulated by a longer quasi periodic ~186-year cycle manifested by the Oort, Wolf, Sporer, Maunder; and Dalton solar minima. The Little Ice Age (1350-1850) was purportedly triggered by the five-decade-long Maunder Minimum (1645-1715). Quite apart from this intrinsic variability of the sun, the Milanković hypothesis attributes the amount of incoming solar radiation (insolation) to Earth’s spin-orbit dynamics. The superposition of the ~100ka oscillation in the planet’s orbital eccentricity, the ~22ka apsidal precession, and the ~41ka oscillation of axial obliquity, has been known to correlate with the time-rate of change of global temperature, which appear to explain the alternating sequence of glacial and interglacial epochs (1ka=1000y). The current interglacial period (the Holocene) has already idled for more than a millennium beyond the mean duration. In order to provide a quantitative connection between insolation and the astrophysical drivers, we describe a streamlined model that allows one to calculate insolation as a function of the the varying solar output and Milanković parameters. Through this quasi-theoretical review, we hope to shed some light on the uncertainties that currently plague climate science.
Keywords: Global warming, climate change, solar variability, sunspot number, solar irradiance, insolation, Milanković cycles, obliquity, eccentricity, apsidal precession, celestial dynamics, Kepler’s Laws, orbit equation, classical perturbation theory, Maunder Minimum, Dalton Minimum, Little Ice Age
1De La Salle University-Manila, 2401 Taft Ave., Manila
* [email protected]
ABSTRACT: Conducting polypyrrole film electrodes for supercapacitor applications were synthesized by direct-current polymerization and by pulsed-current polymerization. The specific capacitances obtained in this study range from 18.7 to 55.6 F/g which is slightly higher than that obtained for commercial supercapacitors with activated carbon electrodes whose maximum range from 20 to 50 F/g. The pulse-polymerized Ppy electrode produced a gravimetric capacitance, 45.6 F/g, that is more than twice that of the DC-polymerized electrode, 20.7 F/g, in 1M of NaCl. When subjected to cycle life test, the specific capacitance of the Ppy film electrodes stabilized after 10 cycles and was found to be highly stable up to 100 cycles with only 1% decrease in specific capacitance. The stabilization time of the Ppy film electrodes in this study are shorter than those from similar studies in which stabilization was only obtained after 100 cycles.
Keywords: supercapacitor; conducting polymer; polypyrrole, pulse-polymerized
1Chemistry Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines 0922
2Biology Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines 0922
3 Material Science and Nanotechnology Research Unit, Center for Natural Sciences and Environmental Research, De La Salle University, 2401 Taft Avenue, Manila, Philippines 0922
*Corresponding author’s email: [email protected]
ABSTRACT: Fabric staining with food items is an unfortunate, everyday occurrence. The development of stain-resistant fabrics has been viewed as a solution to this dilemma. However, quantitative description and information on how food items stain fabrics remain largely unknown. In this study, the thermodynamic and equilibrium properties of how coffee binds on different fabrics were analysed. Gravimetric analysis was conducted which provided a quantitative description on how coffee adsorbs onto different cloths. The principles of adsorption were used to model the binding properties of the different components of coffee. A mathematical relationship was also derived which expressed how fabric surface hydrophobicity affects staining.
Keywords: Adsorption; Langmuir Isotherm; Freundlich isotherm; Adsorption capacity; Binding Constant
De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
Corresponding author: [email protected]
ABSTRACT: Meat is highly prone to spoilage due to bacterial growth which can release off-odors and produce slime. In order to protect people from dangerous health effects brought about the consumption of spoiled meat, an electronic nose system was constructed to evaluate the freshness of meat. Tin Oxide nanomaterials were synthesized using the Horizontal Vapor Phase Growth (HVPG) method. The grown nanomaterial was then characterized under the Scanning Electron Microscope (SEM) and Energy to the meat sample for 3 days with 10 hours data acquisition each day. The odor of the fresh meat and the spoiled meat were also analyzed using Headspace Solid Phase Microextraction (SPME) and Gas Chromatograph – Mass Spectrometry. Results showed that there was an increase in the voltage reading of the fabricated gas sensor as the meat was spoiled for 3 days. Results from the SPME and GC-MS also show that there was only the compound, trimethylsilyl fluoride found in the meat odor when it was fresh and several compounds such as Indole and Palmitic acid were found in the spoiled meat odor. Therefore a relationship between the voltage readings and the presence of the volatile compounds were established to be direct.
Keywords: nanomaterials, horizontal vapour phase growth technique
1Optics and Instrumentation Physics Laboratory, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*Corresponding Author: [email protected]
ABSTRACT: There is a growing interest to studies involving the use of radiofrequency electromagnetic fields (RF-EMF) on biological systems. Exposure to RF-EMF will influence the activity of microbiological organisms but its susceptibility is dependent on the field parameters, such as frequency. In this study, bacteria Bacillus subtilis was exposed to RF-EMF with a carrier frequency of 3.3 MHz. Bacillus subtilis was selected as the biological system to be investigated because of its benefits to medical and dietary field. It was investigated at five different exposure times (i.e. 3, 6, 9, 12, and 15 minutes). The computed sweep frequency for Bacillus subtilis are 85 Hz and 169 Hz as the lower limit and upper limit, respectively. The cytotoxicity test was used to determine the optical density of cell viability through Spectrophotometer. It was then analyzed using the statistical T test and ANOVA test. The result has indicated that the most significant effect on bacteria Bacillus subtilis is at 6 minutes and 12 minutes exposure. Also, serial dilution analysis was used to test for quantitative results for colony growth of the bacteria. The results of the experiment showed that the bacteria were able to proliferate when it was exposed to longer time intervals. This study provides information of the effect of radiofrequency on bacteria Bacillus subtilis.
Keywords: Bacteria bacillus subtilis, radiofrequency electromagnetic fields
1Department of Chemistry, De La Salle University, 2401 Taft Avenue, Manila, 0922 Philippines
2Materials Science and Nanotechnology Unit, Center for Natural Science and Environmental Research, De La Salle University, 2401 Taft Avenue, Manila, 0922, Philippines
*Corresponding author: [email protected]
ABSTRACT: The incorporation of aminopyridine-ligated cobalt (III) phthalocyanine complex [CoIIIPc(ampy)2]SCN (Pc = pthalocyanine, ampy = aminopyridine, SCN = thiocyanate) to titanium doxide (TiO2) is a promising solution for the oxidation of organic air pollutants in indoor environment. The synthesis involves the oxidation of the cobalt (II) central metal from cobalt (II) phthalocyanine (CoIIPc) and a subsequent ligand substitution yielding KCoIIIPc(SCN)2. A dissociation mechanism substitutes the SCN- ligands for the aminopyridine which attaches to the axial positions of CoIII via its pyridine moiety. The synthesis of the final product was confirmed using various characterization techniques.
1Biology Department, De La Salle University, Taft Avenue, 0922 Manila, Philippines
2Mathematics and Statistics Department, De La Salle University, Taft Avenue, 0922 Manila, Philippines 3Materials Science and Nanotechnology Research Unit, Center for Natural Sciences and Environmental Research, De La Salle University, Taft Avenue, 0922 Manila, Philippines
*Corresponding author: [email protected]
ABSTRACT: Accumulated pollutants from air pollution which consists of particulate matter inflict potential health and environment hazards. In this study, the leaves of low lying plants were used as pollution sinks as these are the immediate recipients of pollutants present in our breathing zone. The aim of the study is to evaluate the effectiveness of using low lying plants as bioindicators for microparticle pollution. The study was conducted in February, April and June 2016, by quantifying the amount and size of microparticles on the leaf surface of the plants in three different sites within De La Salle University. Three distinct species were obtained for each location. The microparticles found in the plant species in STRC had the highest mean particle count of 196.0370 and size of 0.024024 mm. In terms of time, the species collected in February had the highest mean particle count of 181.8889 while the ones collected in April had the highest mean particle size of 0.021462 mm. The post hoc test identified STRC as the location with a significant effect on both location and time, while February had the significant effect on count and April on size in terms of collection period. In conclusion, the abundance and variety of microparticles found in the low lying plants is dependent on the location of the species, the weather, and other environmental factors. The results obtained can serve as basis for future studies that would focus on air quality monitoring or low lying plants.
Keywords: air pollution; particulate matter; biondicator; microparticle pollution.
Chemistry Department, De La Salle University,
2401 Taft Avenue, Manila 0922, Philippines
*Corresponding authors: [email protected], [email protected]
ABSTRACT: Bacterial cellulose (BC), characterized by its high purity, strength, moldability and water holding capacity, has attracted several industries in using BC in biotechnology and medical applications. In this study, the diffusion behavior of two polyphenols, namely quercetin and trans-resveratrol (tRSV), in the bacterial cellulose matrix was investigated. The experiments were divided into three set-ups to monitor the diffusion which are polyphenol incorporated bacterial cellulose (BC-tRSV or BC-Quercetin) with solution in the upper chamber (Set-up 1), pure BC with polyphenol in the upper chamber (Set-up 2) and polyphenol incorporated bacterial cellulose in a solution (Set-up 3). Results show significant diffusion in tRSV in all three setups while negligible diffusion was observed in quercetin. Quercetin has more hydroxyl groups than tRSV, which can form extensive intramolecular hydrogen bonding with the microfibrils of BC, causing it to be trapped in its fibril network. On the other hand, tRSV has lower degree of hydroxyl groups and therefore form lesser hydrogen bonding with the BC fibrils. It was concluded that the degree of hydrogen bonding contributed to the diffusion observed. Furthermore, diffusion through the BC (setup 2) and diffusion from the BC (setup 3) both contributed to the diffusion of tRSV, which was quantified using HPLC. The diffusion of tRSV was further confirmed using LCMS. Thus, BC can be utilized as natural, affordable, and effective delivery system of therapeutically relevant drugs.
Keywords: Bacterial cellulose, polyphenol, quercetin, trans-resveratrol, diffusion
1 De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: TiO2 nanomaterials were fabricated via the Horizontal Vapor Phase Growth (HVPG) technique, modified by adding an additional step involving annealing and gas purging. The technique utilized TiO source powder which was sealed inside a quartz tube along with a silicon substrate. The sealed quartz tube was placed inside a programmable furnace that was set to have a dwelling temperature ranging from 900°C to 1200°C, and a growth time between 4 - 8 hours. The tubes were taken out of the furnace after it was allowed to cool to room temperature, and were cracked to obtain the silicon substrates that had been deposited with nanomaterials. The nanomaterials along with the substrate were annealed at 300°C for 1 hour while allowing O2 gas to strike the surface of the substrate. The annealed samples were harvested and were subjected to the characterization process. Using a scanning electron microscope, it was determined that nanostructures formed across the surface of the substrate is in the form of curvy and flexible wires. EDX analysis of these nanostructures showed that it was composed of titanium and oxygen with an approximate stoichiometric ratio of 1 Ti: 2 O. Further characterization of the nanomaterials using XRD analysis verified that the nanowires were indeed TiO2 with both anatase and rutile polymorphs present.
Keywords: nanomaterials, horizontal vapour phase growth technique
De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: In this study, the Horizontal Vapor Phase Growth (HVPG) Technique was used to grow Gallium Nitride (GaN) nanomaterials from Gallium Nitride powders with purity rate of 99.99%. 35 milligrams of the source material was placed in a sealed quartz tube with a pressure of 10^-6 Torr or lower. The quartz tube was heated in a programmable tube furnace set to temperatures of 1100°C, 1000°C, 950°C, 820°C and 750°C with dwell times of 4 hours, 6 hours and 8 hours. Scanning electron microscopy revealed that the gallium nitride nanowires were fabricated for all dwell times for 1100°C, 1000°C, 950°C and 820 °C. Gallium nitride microplates were also fabricated for the 8 hour dwell time for temperatures of 1100°C, 1000°C, 950°C and 750°C, for the 6 hour dwell time for temperatures of 1100°C and 1000°C, and for 4 hour dwell time for temperature of 1100°C. Energy dispersive x-ray revealed that the elemental composition for the gallium nitride nanomaterials were oxygen (34.01%), silicon (40.69%), nitrogen (12.55%), and gallium (12.76%). The Energy dispersive x-ray results confirm the 1: 1 elemental percentage ratio of gallium to nitride. The X-ray diffraction results reveal that a single-phase wurtzite structure was formed. The calculated lattice parameter values are a = 3.190Å and c = 5 .189Å. These are close to the values computed for bulk GaN where a = 3.186Å and c = 5.174Å, and also for GaN nanomaterials where a = 3.191Å and c = 5.189Å. Based on the results, the optimum growth conditions for both nanowire and microplate growth is 1000°C for 6 hours.
Keywords: nanomaterials, horizontal vapour phase growth technique.
1 De La Salle University-Manila, Instrumentation and Optics Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*Corresponding author: [email protected]
ABSTRACT: A non-invasive technique was demonstrated in controlling the growth of three fungi species (Altemaria sp., Geotrichum sp. and Paecilomyces sp.) found on the mural painting of Vicente Manansala. Exploiting the resonant DNA length of these fungi, we were able to tune the pulsed electromagnetic field (PEMF) to debilitate the growth of these fungi cultured on petri dish exposed at different time intervals. Results showed significant decrease in fungal growth if treated at three-minute and ten-minute exposure time. This work can be extended to oil, water, or charcoal painting sample media to address permanent discoloration called foxing.
Keywords: non-invasive technique, conservation, control of fungal growth and mural painting
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: A modified iron-centered phthalocyanine complex was synthesized with axial aminopyridine ligands. The aminopyridine was coordinated with the central metal of the phthalocyanine through dissociative ligand substitution to create terminal amines, which would bond with the growth factors in proteins. This complex may exhibit higher absorption which may help penetrate the tumor tissues better while its paramagnetic properties allow the monitoring of its activity inside the body in the presence of a magnetic field. Characterization using infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, melting point, and solubility tests were performed to substantiate the formation of the [FeIII(Pc)(ampy)2]SCN.
Keywords: phthalocyanine complex, aminopyridine, dissociative ligand substitution, the [FeIII(Pc)(ampy)2]SCN
1 De La Salle University-Manila, Solid State Physics Laboratory 2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: Metal nanoparticles (NPs) have unique chemical, magnetic, electrical, opticyal and mechanical properties compared to their bulk material and because of this, they hgave a lot of promising applications in medicine, electronics and catalysis. Au, Cu, Pt, Pd, aond Ni have been synthesized via vertical Vapor Phase Growth technique. Their respective metal hydrates were used as starting material. Thirty five milligrams (0.035 g) of each was weighed and loaded into a fused silica tubes sealed at a pressure of ~10-6 Torr. The fused silica tubes were then set into temperatures of 1000°C and 1200°C with a growth time of 6 and 4 hours using a Fisher Programmable Muffle Furnace. SEM characterization showed micro- and nanospheres, wires sheets, polyhedrons and irregular structures at which they are mostly found at the samples baked at 1000°C for 6 hours and 1200°C for 4 hours. Mechanisms for the formation of some particles were proposed and discussed. EDX analysis shows that the metals were present in the particles that were synthesized.
Keywords: Hnorizontal Vapor Phase Growth (HVPG) technique; Iron-Oxide; Nanomaterials
1 De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: In this study, a simple Physical Vapor Deposition (PVD) process called the Horizontal Vapor Phase Growth (HVPG) Method was used to grow carbon nanomaterials from two different activated carbon powder, one is an industrial grade activated carbon and another is labeled as PUREBLACK 205 Carbon. The source material was weighed to 0.035 grams and placed in a sealed quartz tube. The quartz tube was the set in a programmable tube furnace and set to temperatures of 1200°C,1000°C, 800°C and 600°C with dwell time of 4 to 8 hours with 2 hours increment for the PUREBLACK 205 Carbon and 8 hours for the industrial grade activated carbon. Scanning Electron Microscopy revealed that the carbon nanomaterials with rod-like structure grew under high vacuum conditions (~10-6 Torr) with a growth temperature of 1200°C for 8 hours using the industrial grade activated carbon. On the other hand, nanowires were found using the PUREBLACK 205 Carbon with high vacuum conditions of approximately 10-6 Torr with a growth temperature of 1200°C for 6 hours. Energy Dispersive X-ray revealed the elemental composition of the nanorods as Carbon (60.05%) and Silicon (49.95%). The nanowires, on the other hand, were made up of Carbon (41.85%), Oxygen (31.53%) and Silicon (26.61%).
Keywords: Horizontal Vapor Phase Growth (HVPG) technique; Activated Carbon; PUREBLACK 205 Carbon; Nanomaterials
1Department of Chemistry, De La Salle University, 2401 Taft Avenue, Manila, Philippines
*corresponding author: [email protected]
ABSTRACT: The etherification of nata de coco was achieved through an SN2 reaction of the freeze dried sheet of the biopolymer with alkyl bromides. Two ether derivatives of nata de coco were separately prepared using 1-bromohexane and 1,6-dibromohexane in warm (50-60oC) pyridine. The resulting products were tested for its swellablity and compared with that of the unreacted nata de coco. Characterization was done using SEM and ATR FT-IR.
Keywords: Nata de coco, etherification, swellability
1 De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: The role of the observer in physics is reconsidered in connection with our evolving assumptions about the nature of time. Unlike the observer’s optional movement through space, evolution in time is compulsory and strictly governed by causal order. Thus, it is argued that time is intrinsically more fundamental than space. The geometry of space is appreciated as an emergent degrees of freedom which allows moving observers to develop invariant transformation equations. Inertial laws are shown to emerge from the observer’s assumptions about the nature of time and its transformations. We are thus led to explore the next logical extension of the observer’s progressing appreciation of the nature of time by allowing time to depend on higher-derivative kinematical quantities. This leads to inertial laws that may potentially accommodate various nonlinear phenomena such as the yet unresolved celestial anomalies, and possibly provide the needed degrees of freedom for the unification of classical with quantum theory.
Keywords: observer, emergent manifold, causality, time dilation, relativity of time, higher-derivative theories, modified inertia, alternative gravity theory
1 Department of Physical Sciences, Philippine Normal University
2 Cultural Heritage Studies Program, University of Santo Tomas Graduate School
3 De La Salle University-Manila, Instrumentation and Optics Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: We demonstrated a non-invasive spectral imaging system in the pigment identification of watercolor paintings. The non-invasive technique used a Digital Light Projector (DLP) and a Sagnac interferometry system that includes an optical module, a cooled CCD camera, and a desktop computer using a Fast Fourier Transform (FFT) computer program to determine the reflectance data of a sampled image. Results show that the non-invasive spectral system can identify pigments with known test swatches with maximum percentage difference of 0.74 %. The reflectance data of the two sample paintings were then statistically computed with known test swatches using t-test to determine the p-value between the known and unknown pigments with test swatches. It is possible to extend this work in which identification of the artist behind the artwork can be done by correlating the p-values of the color pigments with illuminants.
Keywords: non-invasve technique, spectral imaging system, color pigment analysis, Sagnac interferometry and watercolor painting.
1 De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: Hematite iron oxide (α - Fe2O3) was synthesized through the process called Horizontal Vapor Phase Growth (HVPG) with and without silicon substrate. Though the source material had a purity rate of 97.60%, it did not inhibit the growth of nanomaterials. The HVPG technique was able to isolate the impurities specifically at zone 3 with the intended nanomaterial products grown at zone 2 which made the synthesis distinctive in its purpose. The growth temperature was varied at 900oC, 1000oC, 1100oC and 1200oC with dwell times of 4, 6, and 8 hours respectively. Nanomaterials without substrate revealed hexagonal nanoplates with an average thickness of 70 nm grown at 1100ºC for 8 hours. Energy Dispersive X-ray (EDX) obtained from the nanomaterial without substrate shows an atomic percentage of 25.56 % Fe, 12.75% Si, and 61.70% O. The iron oxide formed was indeed hematite and was also consistent with the elemental ratio of Fe, O, and Si of 2:5:1. Silicon was included in the analysis due to the silicate composition of the quartz tube. For samples grown on silicon substrate, hexagonal nanoplates were also observed with an average thickness of 80 nm grown at 1000ºC for 8 hours. Results from EDX showed a stoichiometric ratio of 40% Fe and 60% O indicating that the nanomaterial formed was indeed α- Fe2O3. The crystal structure of the nanomaterial exhibited a low intensity X-ray Diffraction (XRD) brought about by the random direction of the samples though an XRD peak was obtained at 41º with a plane of index of (311).
Keywords: Horizontal Vapor Phase Growth (HVPG) technique; Iron-Oxide; Nanomaterials
De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: The synthesis of platinum nanomaterials was done using Horizontal Vapor Phase Crystal (HVPC) growth technique for hydrogen fuel cell application.
Thirty five milligrams of platinum powder with 99.99% purity was used in the synthesis. Growth temperature was set to 800°C, 1000°C and 1200°C, growth times were 10 hours and 12 hours with ramp time was set to 60 minutes.
SEM was used to investigate the surface morphology and EDX was used to determine the elemental composition of platinum nanomaterials deposited in the substrate. Results show that platinum nanomaterials with diameter less than 100 nm are dispersed into substrate. The optimum result can be done at growth temperatures of 1000°C and 1200°C and growth times of 10 hours and 12 hrs.
Synthesized platinum nanomaterials are used for hydrogen fuel cell application. This study found out that 0.93 V off-voltage can be produced by hydrogen fuel cell with platinum nanomaterials. When it is connected to a propeller (2.3 ohms), hydrogen fuel cell can produced 0.76 V.
This study varied the oxygen supplied to hydrogen fuel cell with platinum nanomaterials. It was found out that the hydrogen fuel cell with platinum nanomaterials only produced 0.47 V when supplied by ambient air. The voltage time graph for hydrogen fuel cell with platinum nanomaterials was utilized to determine the Faraday efficiency. Results show that hydrogen fuel cell with platinum nanomaterials has Faraday Efficiency of 48.61%.
Keywords: Horizontal Vapor Phase Growth (HVPG) technique; Platinum; Hydrogen Fuel Cell; Nanomaterials
1 De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: Zinc sulfide (ZnS) nanoparticles, jagged-edge nanorods, nanorods, nanofilaments, irregularly-shaped nanosheets, hexagonal nanosheets, nanoflakes, nanowires, nanobelts, nanostrips, nanoribbons, and nanowindmills were successfully synthesized from a minimal amount of ~35 mg ZnS powder of 99.9 % purity via Horizontal Vapor Phase Crystal Growth (HVPCG) at an 80-min ramp time. The growth temperature was varied from 600 °C-1200 °C in 200 °C increment with dwell time set to 4, 6, and 8 hours. The type of nanostructure formed was very sensitive to growth temperature, dwell time as well as quenching. Nanofilaments, nanorods and hexagonal nanosheets morphologies were abundantly produced under several growth conditions while the nanostrips, nanoribbons, jagged-edge nanorods, and nanowindmills occured only at a particular growth temperature, dwell time, and quenching. The effect of quenching on the formation of nanostructure was mostly observed at higher growth temperature and longer dwell time. EDX analyses revealed the atomic composition of the nanostructures. The ratio of Zn to S was close to 1:1. X-ray diffraction test result showed that the deposited nanomaterials with growth temperature of 1000 °C, dwell time of 4 hours and quenched at ~1.2 °C had wurtzite or hexagonal crystal structure. Photoluminescence (PL) tests suggested the deficiency in sulfur and quantum confinement of the nanostructures grown at 1000 °C and 1200 °C for 4, 6, and 8 hours for both the quenched and unquenched set ups.
Keywords: Horizontal Vapor Phase Crystal Growth (HVPCG) technique; Zinc Sulfide; Nanomaterials
1 De La Salle University-Manila, Solid State Physics Laboratory
2401 Taft Ave. Manila, 1004 Philippines
*corresponding author: [email protected]
ABSTRACT: Gallium Nitride is a semiconductor material that has been reviewed as an ideal material for electronic devices. This is because Gallium Nitride is a material that has a direct energy gap of 3.4 eV which allows it to function well in high power devices. This study showed that Gallium Nitride is a suitable material in the production of light emitting diodes. The nanomaterials were grown using the Horizontal Vapor Phase growth method and was subject to analysis under the scanning electron microscope and energy dispersive x-ray. Results of the Scanning Electron Microscopy indicated that the nanostructures were nanohexagons and malformed nanohexagons since the process does not involve a catalyst and substrate that made the products grew in random direction. Energy Dispersive X-Ray analysis showed that indeed the nanomaterial was GaN although there were impurities such as Carbon, Oxygen, and Nitrogen. The photoluminescence of the GaN nanomaterial was tested under a spectral microscope to determine the energy gap and spectra the nanomaterial would emit when excited. The energy gap was calculated to be 1.8 eV, 2.31 eV, and 3.1 eV where indicative of green, red, and blue spectra of the GaN nanomaterial, respectively. Thus, with the results of the PL, of the GaN nanomaterial, with appropriate electronic design, the GaN nanomaterial is suitable for LED applications.
Keywords: Horizontal Vapor Phase Growth (HVPG) technique; Gallium Nitride; Nanomaterials
electrode (10), a variable resistor (21) electrically
coupled in parallel to the gas sensor electrode (10),
5 and a voltage measuring circuit (22) electrically
coupled in parallel to the variable resistor (21). The ,):'
gas sensor electrode (10) includes a substrate (11) and './1
a gas sensing layer (12) that is formed on the substrate
(11) and made of a tin oxide semiconducting nanomaterial Co)
10 having a resistivity not greater than 5000 ohm-meter.
A process for forming the gas sensor electrode (10) is
also disclosed.
approach while 93 respondents as the experimental group for the GIS-based approach. The total number of items for the SCIENVP concept test was 81 and 68 items for the LBYENVP concept test. The experimental group was given the student evaluation questionnaire (SEQ) and GIS awareness and
preparedness survey (GAPS). The GAPS questions are arranged according to respondent’s ICT proficiency, school’s ICT capability, respondent’s GIS proficiency, effect of GIS and GIS integration. The training of teachers was done during the 2nd term of the AY 2011-2012 while the study was implemented on the 3rd term AY 2011-2012. The study revealed that GIS-based learning has a significant correlation between the students’ scores and the method of teaching based on Chi-square test.
Comparing the mean posttest scores using tabular Z-test at 0.95 ±1.64, SCIENVP Z-test result obtained 2.61 while LBYENVP had 2.21 which lie outside the region of acceptance. This signifies that the GIS based method significantly increased the students’ level of understanding than that of the traditional
method.