Quezon City, Philippines

Nueva Vizcaya State University

Quezon City, Philippines

The Nueva Vizcaya State University is a public university in the Philippines. It is mandated to provide advanced instruction and professional training in agriculture, arts, science, technology, education and other related fields. It is also mandated to undertake research and extension services, and provide progressive leadership in its area of specialization. Its main campus is located in Bayombong, Nueva Vizcaya, Philippines. The University was established through the merger of Nueva Vizcaya State Institute of Technology in Bayombong and Nueva Vizcaya State Polytechnic College in Bambang. Wikipedia.

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Combalicer E.A.,Korea forest Research Institute | Combalicer E.A.,Nueva Vizcaya State University | Cruz R.V.O.,University of the Philippines at Los Baños | Lee S.H.,Korea forest Research Institute | Im S.,Korea forest Research Institute
Journal of Tropical Forest Science | Year: 2010

tropical forest watershed in the Philippines. Hydrologic modelling has become an indispensable tool and cost-effective process in understanding the movement of water loss in the Molawin rainforest watershed, Philippines. The study aimed to optimise the use of a lumped BROOK90 model and simulate the hydrologic processes distribution in a given watershed. The rating curve model was developed as a basis for hydrologic modelling. The model was calibrated at catchment scale to avoid subjectivity of various variable parameters by considering the topography, morphology, climate, soil and canopy characteristics. Five years of streamflow discharge measurements were considered for the model sensitivity analysis, calibration and validation. Results showed a good agreement between observed and simulated streamflows during calibration (r = 0.87 and E = 0.87) and validation (r = 0.84 and E = 0.81) periods. As a consequence, the major hydrologic processes distribution accounted for 41% of the precipitation that turned into evaporation, while 49% became streamflow and 10% remained in deep seepage loss. Overall, the distribution of hydrologic components is primarily reflected during pronounced seasonal variations and fluctuating patterns in precipitation.

Combalicer E.A.,Nueva Vizcaya State University | Combalicer E.A.,Seoul National University | Cruz R.V.O.,University of the Philippines at Los Baños | Lee S.,Seoul National University | Im S.,Seoul National University
Journal of Earth System Science | Year: 2010

A statistical downscaling known for producing station-scale climate information from GCM output was preferred to evaluate the impacts of climate change within the Mount Makiling forest watershed, Philippines. The lumped hydrologic BROOK90 model was utilized for the water balance assessment of climate change impacts based on two scenarios (A1B and A2) from CGCM3 experiment. The annual precipitation change was estimated to be 0.1-9.3% increase for A1B scenario, and -3.3 to 3.3% decrease/increase for the A2 scenario. Difference in the mean temperature between the present and the 2080s were predicted to be 0.6-2.2°C and 0.6-3.0°C under A1B and A2 scenarios, respectively. The water balance showed that 42% of precipitation is converted into evaporation, 48% into streamflow, and 10% into deep seepage loss. The impacts of climate change on water balance reflected dramatic fluctuations in hydrologic events leading to high evaporation losses, and decrease in streamflow, while groundwater flow appeared unaffected. A study on the changes in monthly water balance provided insights into the hydrologic changes within the forest watershed system which can be used in mitigating the effects of climate change. © Indian Academy of Sciences.

Mostafa E.,Cairo University | Mostafa E.,Seoul National University | Lee I.-B.,Seoul National University | Song S.-H.,Seoul National University | And 7 more authors.
Biosystems Engineering | Year: 2012

An investigation was conducted to develop ventilation systems to prevent cold air drafts during the winter season and create a suitable atmosphere inside the broiler rearing building. In the cold weather, ventilation ducts and low ventilation rates are used to maintain the required air temperature. Perforated ducts are preferred for heating spaces because they provide efficient and uniform distribution of the entire air volume. Four ventilation systems were designed in order to establish a comfortable zone for the broilers during winter season. To investigate these different systems under realistic conditions, computational fluid dynamic simulation was used. Field experiments were conducted to validate the designed cases. From the validation results, very low errors were observed. The improved designs were compared with the standard design in terms of ventilation rate, air temperature distribution and indoor gas concentration reduction. Case four (C-4) of the improved designs achieved the highest ventilation rate in the broiler zone. In C-4, theinlet duct was installed in building side and the outlet duct in the opposite side. It achieved about 54% of the ventilation in comparison to standard design. All improved designs showed high uniformity ranging around 60-70% compared to the standard design. For gas dilution in broiler zone, C-4 showed 15% ammonia reduction efficiency 3 min after operating the ventilator. © 2012 IAgrE.

Yago J.I.,University of Florida | Yago J.I.,Nueva Vizcaya State University | Lin C.-H.,University of Florida | Lin C.-H.,Brown University | Chung K.-R.,University of Florida
Molecular Plant Pathology | Year: 2011

Fungi respond and adapt to different environmental stimuli via signal transduction systems. We determined the function of a yeast SLT2 mitogen-activated protein (MAP) kinase homologue (AaSLT2) in Alternaria alternata, the fungal pathogen of citrus. Analysis of the loss-of-function mutant indicated that AaSLT2 is required for the production of a host-selective toxin, and is crucial for fungal pathogenicity. Moreover, the A.alternata slt2 mutants displayed hypersensitivity to cell wall-degrading enzymes and chemicals such as Calcofluor white and Congo red. This implicates an important role of AaSLT2 in the maintenance of cell wall integrity in A.alternata. The A.alternata slt2 mutants were also hypersensitive to a heteroaromatic compound, 2-chloro-5-hydroxypyridine, and a plant growth regulator, 2,3,5-triiodobenzoic acid. Developmentally, the AaSLT2 gene product was shown to be critical for conidial formation and hyphal elongation. Compared with the wild-type, the mutants produced fewer but slightly larger conidia with less transverse septae. The mutants also accumulated lower levels of melanin and chitin. Unlike the wild-type progenitor, the A.alternata slt2 mutants produced globose, swollen hyphae that did not elongate in a straight radial direction. All defective phenotypes in the mutant were restored by transformation and expression of a wild-type copy of AaSLT2 under the control of its endogenous promoter. This study highlights an important role of the AaSLT2 MAP kinase-mediated signalling pathway, regulating diverse physiological, developmental and pathological functions, in the tangerine pathotype of A.alternata. © 2011 The Authors. Molecular Plant Pathology © 2011 BSPP and Blackwell Publishing Ltd.

Bitog J.P.,Nueva Vizcaya State University | Lee I.-B.,Seoul National University
Acta Horticulturae | Year: 2013

Windbreak systems play an active role in improving the quality of the natural environment, accelerating the development of agriculture, forestry and animal husbandry, and increasing ecological, social and economical benefits. In a vast reclaimed land, where dusts are of enormous concern, windbreak's main purpose can be exclusively to control soil erosion, dust generation and dispersion. Artificial and natural windbreaks are very effective in reducing the wind velocity in the dust source areas, where wind is the main catalyst of soil erosion, dust generation and diffusion. In this study, numerical simulation was utilized to evaluate the performance of both artificial and natural windbreaks in minimizing wind velocity. Windbreak fences of various height and porosity arranged in an array with different gap distances were studied. For natural windbreaks, the effectiveness of trees in reducing the wind velocity was measured and quantified. Field experiments and wind tunnel studies were conducted to establish the validity of the simulation models. Simulation results were evaluated and suitable windbreak design for artificial and natural windbreaks were recommended. The numerical technique used in the study has proven its validity in investigating dusts generation and diffusion which saves significant amount of time, labor and cost.

Bitog J.P.,Seoul National University | Bitog J.P.,Nueva Vizcaya State University | Lee I.-B.,Seoul National University | Lee C.-G.,Inha University | And 7 more authors.
Computers and Electronics in Agriculture | Year: 2011

The past decade has seen a rapid increase of numerical simulation studies on photobioreactors (PBRs). Developments in computational fluid dynamics (CFD) and the availability of more powerful computers have paved the way for the modeling and designing PRBs, a strategy that was abandoned from the late 1970s until the 1980s because of its complexity. This paper reviews the present status of numerical modeling for PBRs as well the application of CFD in the design of PBR for the mass production of microalgae. Emphasis is on the major breakthroughs in PBR design that may lead to scaling-up. Most simulations have been conducted in bubble column PBRs, which offer many advantages. Their geometry is simple in design with no moving parts, and they are easy to construct and operate. A majority of published simulation studies used two-phase models (air and water) and employed the Eulerian-Eulerian mixture model. CFD models have been vigorously validated by experimental and laboratory studies, with most claiming to have achieved good results. However, current PBR scale-up projects still need to resolve hydrodynamic issues within the PBR, in order to optimize factors for microalgal growth. To create ideal conditions inside the PBR, the main factors that influence microalgal growth such as light intensity and distribution, gas injection and mixing, and hydrodynamics/flow pattern which are the key for design and scale up must be thoroughly understood. The present practice of PBR design using CFD can be considered both an art and a science because of some numerical simulation issues which are yet to be resolved and the complexity of fluid mechanics inside the PBRs. Nonetheless, CFD has proven to be an effective tool in predicting the complex inherent phenomena in the PBRs. The CFD technique has shown to be very promising to successfully design and develop PBRs which can be commercially available for scale-up. © 2011 Elsevier B.V.

Lee I.-B.,Seoul National University | Bitog J.P.P.,Seoul National University | Bitog J.P.P.,Nueva Vizcaya State University | Hong S.-W.,Seoul National University | And 4 more authors.
Computers and Electronics in Agriculture | Year: 2013

Computational fluid dynamics (CFD) is a proven simulation tool which caters to almost any field of study. The CFD technique is utilized to simulate, analyze, and optimize various engineering designs. In this review, the discussion is focused on the application of CFD in the external atmospheric processes as well as modeling in land and water management. With respect to its application in environmental investigations, numerous CFD studies have been done in the atmospheric processes where generally only the fluid flow characteristics are investigated. The application of CFD to soil and water management is still limited. However, with the present demand for conservation and sustainable management of our soil and water resources, CFD application in this field is fast emerging especially in structure designs of dams and reservoirs where CFD offers fast reliable results with less labor and cost. Every CFD model should be validated in order to be considered accurate and reliable. However, a benchmark or standard procedures in validating CFD models is not yet available. This probably answers why the success of the CFD models is still mostly attributed to the user's skills and experience. At present, the degree of application of CFD to the agro-environmental field is limited by the computing power and software used, however, the fast ever computing power of PCs continually expands the potential of CFD and can be generally more flexible at accounting for the unique aspects of every CFD project. This allows easy access to conduct simulation studies from simple to complex models. In this paper, after a state of art analysis of the past and present application of CFD in the agro-environmental applications, its future directions were discussed, in order to potentially serve as a guide for researchers and engineers on what project or investigations can be conducted. © 2012 Elsevier B.V.

Bitog J.P.P.,Nueva Vizcaya State University | Lee I.-B.,Seoul National University | Oh H.-M.,Korea Research Institute of Bioscience and Biotechnology | Hong S.-W.,Catholic University of Leuven | And 2 more authors.
Biosystems Engineering | Year: 2014

A numerical simulation using computational fluid dynamics (CFD) was utilised to investigate the flow hydrodynamics of cylindrical bubble column type photobioreactors (PBRs) with a 30. l culture medium. To establish the reliability of the simulation study, the CFD model was validated using particle image velocimetry (PIV) computed data under various air flow rates. There were 32 simulation cases for the study comprising two PBR designs, four air flow rates and four nozzle size diameters. Hydrodynamic analyses such as % volume of dead zones, average circulation time and turbulence intensity inside the simulated PBRs were evaluated. Results have shown that the most appropriate PBR for microalgae cultivation was a design with internal baffle and an extended cone-shaped bottom section. In addition, the recommended nozzle diameter was found to be 10mm and a minimum air flow rate of 0.10vvm. To eliminate dead zones inside the PBR, the flow rate can be slightly increased but should not exceed 0.15vvm. Practical evaluation through laboratory experiments has further confirmed the results of the study where the biomass concentration of Chlorella vulgaris from the proposed PBR was significantly higher compared to the standard PBR design. Based on the numerical investigation and practical evaluation, the improved PBR can be seen to be more effective in culturing microalgae particularly for larger scale mass production. © 2014 IAgrE.

Alamo L.S.T.,Maejo University | Alamo L.S.T.,Nueva Vizcaya State University | Tangkuaram T.,Maejo University | Satienperakul S.,Maejo University
Talanta | Year: 2010

A pervaporation-flow injection (PFI) method was developed for the determination of sulfite in selected food samples using a copper hexacyanoferrate-carbon nanotube (CuHCF-CNT)-modified carbon paste electrode. The electrochemical behavior of the modified electrode was observed using cyclic voltammetry in comparison to a CuHCF-modified carbon paste electrode and a bare carbon paste electrode at a scan rate of 100 mV s-1 in 0.10 M KNO3. The bare carbon paste electrode gave the lowest response to sulfite, while the presence of CuHCF made the detection of sulfite possible through electrocatalytic oxidation by the hexacyanoferrate in the modified electrodes. The presence of CNT in the CuHCF-CNT-modified sensor gave the most remarkable current for the detection of sulfite and was then used as a working electrode in the amperometric flow-through cell in the pervaporation flow injection system. The PFI method involves the injection of a standard or sample sulfite solution into a sulfuric acid donor stream to generate sulfur dioxide gas and evaporate into the headspace of the pervaporation unit. The sulfur dioxide diffuses through the PTFE hydrophobic membrane into a potassium nitrate acceptor stream and reverts to the sulfite form, which, subsequently, is transported to the electrochemical flow cell where it is analyzed amperometrically at a CuHCF-CNT-modified electrode at +0.55 V (vs. Ag/AgCl). The detection was determined to be applicable in the sulfite concentration range of 0.5-50 mg L-1. The sensitivity, detection limit, and sample throughput were determined to be 2.105 nA L mg-1, 0.40 mg L-1 and 11 h-1, respectively. The developed PFI method, coupled with the CuHCF-CNT-modified carbon paste electrode, was applied in the determination of sulfite content in sulfite-containing food products. The results agreed well with those obtained through the officially recommended differential pulse polarographic method. © 2010 Elsevier B.V.

PubMed | Nueva Vizcaya State University and Hokkaido University
Type: Journal Article | Journal: The Analyst | Year: 2016

The development of a competitive immunoassay system for colorimetric detection on microfluidic paper-based analytical devices (PADs) is reported. The PADs were fabricated via photolithography to define hydrophilic flow channels and consisted of three main elements: the control and test zones, where target detection was performed, the sample introduction zone, and the competitive capture zone located between the sample introduction zone and the test zone. The chromogenic substrate 3,3,5,5-tetramethylbenzidine (TMB) was deposited at the control and test zones. PAD surface modification was performed at the capture zone first via chitosan activation, then the BSA-conjugated target compound was immobilized. The sample solution consisting of the target compound, the peroxidase-conjugated antibody, and the hydrogen peroxide oxidizing agent was introduced into the device and competition occurred at the capture zone, allowing only the target-bound peroxidase-conjugated antibody to travel past the capture zone and into the test zone via capillary action. The developed competitive immunoassay system was successfully demonstrated on the PAD detection of biotin as a model compound with a detection limit of 0.10 g mL

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