• Environmental Engineering Research
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• v.11 no.3
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• pp.156-163
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• 2006

In this study, substrate removal characteristics were analyzed to reduce the cost of external carbon dosage at Sudokwon Landfill Site Management Corporation in Korea by utilizing oxygen uptake rate (OUR) and nitrate uptake rate (NUR) tests. To estimate and evaluate the substrate removal characteristics obtained by the batch tests, the lab-scale MLE process was operated. By-products of J Co. (sugar manufactory) and S Co. (fine chemical industry) were selected as the concerned carbon sources through a comparison of carbon and nitrogen contents. MeOH was tested as a control experiment. Until the steady state, the fraction of $RBDCOD_{OUR}$ concentration to COD concentration of J Co., S Co. by-products and MeOH increased and reached levels of 98%, 82%, and 100%, respectively. During the 20th operating day, the fraction of $RBDCOD_{NUR}$ concentration to COD concentration was 95%, 81%, and 83%, respectively. These fractions of $RBDCOD_{NUR}$ concentration to $RBDCOD_{OUR}$ concentration increased according to acclimation periods and reached levels of 99%, 97%, and 81%, respectively, on the 20th day. The results obtained from the lab-scale MLE process operation using the concerned carbon sources as external carbon were similar to that observed by OUR and NUR tests.

• Advances in nano research
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• v.9 no.1
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• pp.25-32
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• 2020

In this work, we report the use of caffeine as an alternative source of nitrogen to successfully dope graphene (quaternary 400.6 eV and pyridinic at 398 eV according XPS), as well as the growth of silver nanowires (in-situ) in the surface of nitrogen doped graphene (NG) sheets. We used the improved graphene oxide method (IGO), chemical reduction of graphene oxide (GOx), and impregnation with caffeine as source of nitrogen for doping and subsequently, silver nanowires (NW) grow in the surface by the reduction of silver salts in the presence of NG, achieving a numerous of growth of NW in the graphene sheets. As supporting experimental evidence, the samples were analyzed using conventional characterization techniques: SEM-EDX, XRD, FT-IR, micro RAMAN, TEM, and XPS.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.449-456
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• 2023

Sugar or dextrose increases the cost of production of xanthan gum by Xanthomonas campestris. Brewers' Spent Grain (BSG) was chosen as a source of fermentable sugars. BSG is a significant industrial by-product generated in large quantities from the breweries. Primarily used as animal feed due to its high fiber and protein content, BSG holds great potential as an economically and ecologically sustainable substrate for fermenting biomolecules. This study explores BSG's potential as a cost-effective carbon source for producing xanthan, utilizing Xanthomonas campestris NCIM 2961. An aqueous extract was prepared from BSG and inoculated with the bacterium under standard fermentation conditions. After fermentation, xanthan gum was purified using a standard protocol. The xanthan yield from BSG media was compared to that from MGYP media (control). The fermentation parameters, including pH, temperature, agitation and duration were optimized for maximum xanthan gum yield by varying them at different levels. Following fermentation, the xanthan gum was purified from the broth by alcoholic precipitation and then dried. The weight of the dried gum was measured. The obtained xanthan from BSG under standard conditions and commercial food-grade xanthan were characterized using FTIR. The highest xanthan yields were achieved at 32 ℃, pH 6.0, and 72 h of fermentation at 200 rpm using BSG media. The FTIR spectra of xanthan from BSG media closely resembled that of commercial food-grade xanthan. The results confirm the potential of BSG as a cost-effective alternative carbon source for xanthan production, thereby reducing production costs and solid waste.

• Journal of Plant Biotechnology
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• v.34 no.2
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• pp.111-118
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• 2007

Global warming crisis due primarily to continued green house gas emission requires impending change to renewable alternative energy than continuously depending on exhausting fossil fuels. Bioenergy including biodiesel and bioethanol are considered good alternatives because of their renewable and sustainable nature. Bioethanol is currently being produced by using sucrose from sugar beet, grain starches or lignocellulosic biomass as sources of ethanol fermentation. However, grain production requires significant amount of fossil fuel inputs during agricultural practices, which means less competitive in reducing the level of green house gas emission. By contrast, cellulosic bioethanol can use naturally-growing, not-for-food biomass as a source of ethanol fermentation. In this respect, cellulosic ethanol than grain starch ethanol is considered a more appropriate as a alternative renewable energy. However, commercialization of cellulosic ethanol depends heavily on technology development. Processes such as securing enough biomass optimized for economic processing, pretreatment technology for better access of polymer-hydrolyzing enzymes, saccharification of recalcitrant lignocellulosic materials, and simultaneous fermentation of different sugars including 6-carbon glucose as well as 5-carbon xylose or arabinose waits for greater improvement in technologies. Although it seems to be a long way to go until commercialization, it should broadly benefit farmers with novel source of income, environment with greener and reduced level of global warming, and national economy with increased energy security. Mission-oriented strategies for cellulosic ethanol development participated by government funding agency and different disciplines of sciences and technologies should certainly open up a new era of renewable energy.

• Journal of Plant Biotechnology
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• v.34 no.2
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• pp.103-109
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• 2007

The increasing industrialization of the world has led to precipitous rise for the demand of petroleum-based fuels. The world is presently confronted with the twin crises of fossil fuel depletion and environmental pollution. The search for alternative fuels, which promise a harmonious correlation with sustainable development, energy conservation, efficiency and environmental preservation, has become highly pronounced in the present. Bioenergy is playing an increasingly important role as an alternative and renewable source of energy. Use of Bioenergy has several potential environmental advantages. The most important perhaps is reduction in life cycle greenhouse gases emissions relatives petroleum fuels, since bioenergy is derived from plants which convert Carbon dioxide ($CO_{2}$) into Carbohydrates in their growth. Bioenergy includes solid biomass, biomas and liquid bio-fuels which are fuels derived from crop plants, and include biomass that's directly burned. The two most important bio liquid fuels today are bioethanol from fermenting grain, grass, straw or wood, and biodiesel from plant seed oil.

• Advances in Automotive Engineering
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• v.1 no.1
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• pp.79-104
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• 2018

A detailed literature review is presented for the applications of the heat pump technologies on the electric vehicles Heating, Ventilation and Air Conditioning (HVAC) system. Due to legal regulations, automotive manufacturers have to produce more efficient and low carbon emission vehicles. Electric vehicles can be provided these requirements but the battery technologies and energy managements systems are still developing considering battery life and vehicle range. On the other hand, energy consumption for HVAC units has an important role on the energy management of these vehicles. Moreover, the energy requirement of HVAC processes for different environmental conditions are significantly affect the total energy consumption of these vehicles. For the heating process, the coolant of internal combustion (IC) engine can be utilized but in electric vehicles, we have not got any adequate waste heat source for this process. The heat pump technology is one of the alternative choices for the industry due to having high coefficient of performance (COP), but these systems have some disadvantages which can be improved with the other technologies. In this study, a literature review is performed considering alternative refrigerants, performance characteristics of different heat pump systems for electric vehicles and thermal management systems of electric vehicles.

• Journal of ILASS-Korea
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• v.12 no.4
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• pp.204-210
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• 2007

The worldwide energy problem and global warming cause the need of alternative fuels which feature low carbon-dioxide emission and another energy source. Liquefied Petroleum Gas (LPG) is one of the alternative fuels widely used as domestic and transportational fuel. The third generation LPLi fuel supply system has merits in the increase of engine power and low emissions. The injectors used in LPLi system should overcome a leakage problem and satisfy the durability conditions. Therefore, 1000 hour durability test of the injectors was carried out throughout this research. First, the spray pattern and the penetration length of the selected injectors is graphically shown. Next, the leakage amount with respect to the injection cycle is introduced. Finally, the shapes of nozzle holder and nozzle tip after durability test was investigated by analyzing the microscopic image of the injector tip. The variation in the shape of nozzle tip mainly due to the residue of rubber materials is found to be the reason for leakage.

• Clean Technology
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• v.27 no.3
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• pp.269-274
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• 2021

Bioenergy is generally considered to be one of the options for pursuing carbon neutrality. However, for a period of time, combustion of harvested plant biomass inevitably causes more carbon dioxide in the atmosphere than combustion of fossil fuels. This paper proposes a method that predicts and minimizes the total amount and payback period of this carbon debt. As a case study, a carbon cycle impact assessment was performed for immediate switching of the currently used fossil fuels to biomass. This work points out a fundamental vulnerability in the concept of carbon neutrality. As an action plan for the sustainability of bioenergy, formulas for afforestation proportional to the decrease in the forest area and surplus harvest proportional to the increase in the forest mass are proposed. The results of optimization indicate that the carbon debt payback period is about 70 years, and the carbon dioxide in the atmosphere increases by more than 50% at a maximum and 3% at a steady state. These are theoretically predicted best results, which are expected to be worse in reality. Therefore, biomass is not truly carbon neutral, and it is inappropriate as an energy source alternative to fossil fuels. The method proposed in this work is expected to be able to contribute to the approach to carbon neutrality by minimizing present and future carbon debt of the bioenergy that is already in use.

• Environmental Engineering Research
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• v.19 no.3
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• pp.293-298
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• 2014

An anaerobic photosynthetic treatment process utilizing purple non-sulfur photosynthetic bacteria (PNSB) was applied to the recovery of organic carbon from food processing wastewater. PNSB cells, by-product from the treatment, have high nutrition such as proteins and vitamins which are a good alternative for fish feed. Effects of light source on performance of anaerobic photosynthetic process were investigated in this study. Two bench-scale photo-bioreactors were lighted with infrared light emitting diodes (LEDs) and tungsten lamps covered with infrared transmitting filter, respectively, aiming to supply infrared light for photosynthetic bacteria growth. The photo-bioreactors were operated to treat noodle-processing wastewater for 323 days. Hydraulic retention time (HRT) was set as 6 days. Organic removals in the photo-bioreactor lighted with infrared LEDs (91%-95%) was found higher than those in photo-bioreactor with tungsten lamps with filter (79%-83%). Biomass production in a 150 L bench-scale photo-bioreactor was comparable to a 8 L small-scale photo-bioreactor in previous study, due to improvement of light supply efficiency. Application of infrared LEDs could achieve higher treatment performance with advantages in energy efficiency and wavelength specifity.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.6
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• pp.538-543
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• 2006

A packed bed reactor (PBR) was fed with nitrate containing synthetic wastewater or effluent from a sequencing batch reactor used for nitrification. The C source introduced into the PBR consisted of volatile fatty acids (VFAs) produced from anaerobic acidogenesis of food wastes. When nitrate loading rates ranged from $0.50\;to\;1.01\;kg\;N/m^{3}{\cdot}d$, the PBR exhibited $100{\sim}98.8%\;NO_{3}^{-}-N$ removal efficiencies and nitrite concentrations in the effluent ranged from $0\;to\;0.6\;NO_{2}^{-}-N\;mg/L$. When the PBR was further investigated to determine nitrate removal activity along the bed height using a nitrate loading rate less than $1.01\;kg\;N/m^{3}{\cdot}d$, 100% nitrate removal efficiency was observed. Approximately 83.2% nitrate removal efficiency was observed in the lower 50% of the packed-bed height. When reactor performance at a C/N ratio of 4 and a C/N ratio of 5 was compared, the PBR showed better removal efficiency (96.5%) of nitrate and less nitrite concentration in the effluent at the C/N ratio of 5. VFAs were found to be a good alternative to methanol as a carbon source for denitrification of a municipal wastewater containing 40 mg-N/L.