Biotransformation of lysine into cadaverine using barium alginate-immobilized Escherichia coli overexpressing CadA

Bhatia, S. K.,Kim, Y. H.,Kim, H. J.,Seo, H. M.,Kim, J. H.,Song, H. S.,Sathiyanarayanan, G.,Park, S. H.,Park, K.,Yang, Y. H. Springer Science + Business Media 2015 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.38 No.12

Microbial production of volatile fatty acids: current status and future perspectives

Bhatia, S. K.,Yang, Y. H. Springer Science + Business Media 2017 Reviews in environmental science and bio/technolog Vol.16 No.2

<P>Volatile fatty acids (VFAs) are used as building blocks to synthesize a wide range of commercially-important chemicals. Microbially produced VFAs (acetic acid, propionic acid, butyric acid, isobutyric acid, and isovaleric acid) can be considered as a replacement for petroleum-based VFAs due to their renewability, degradability, and sustainability. The main objective of this review is to summarize research and development of VFA production methods via microbial routes, their downstream processes, current applications, and main challenges. Various fermentation processes have been developed to produce of VFAs starting from commercially-available sugars and other raw materials such as lignocellulose, whey, and waste sludge. Only few microbes have been explored for their potential to produce VFAs, and very little genomic information data is available at the present time. There is a need to use metabolic engineering, systematic biology, evolutionary engineering, and bioinformatics to discover VFA biosynthesis routes since the pathways for isobutyric acid and isovaleric acids are still not well understood.</P>

Production of (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer from coffee waste oil using engineered Ralstonia eutropha

Bhatia, S. K.,Kim, J. H.,Kim, M. S.,Kim, J.,Hong, J. W.,Hong, Y. G.,Kim, H. J.,Jeon, J. M.,Kim, S. H.,Ahn, J. Springer Science + Business Media 2018 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.41 No.2

<P>Polyhydroxyalkonate (PHA) is a type of polymer that has the potential to replace petro-based plastics. To make PHA production more economically feasible, there is a need to find a new carbon source and engineer microbes to produce a commercially valuable polymer. Coffee waste is an inexpensive raw material that contains fatty acids. It can act as a sustainable carbon source and seems quite promising with PHA production in Ralstonia eutropha, which is a well-known microbe for PHA accumulation, and has the potential to utilize fatty acids. In this study, to make poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(HB-co-HHx)), which has superior properties in terms of biodegradability, biocompatibility, and mechanical strength, engineered strain Ralstonia eutropha Re2133 overexpressing (R)-specific enoyl coenzyme-A hydratase (phaJ) and PHA synthetase (phaC2) with deletion of acetoacetyl Co-A reductases (phaB1, phaB2, and phaB3) was used to produce PHA from coffee waste oil. At a coffee oil concentration of 1.5%, and C/N ratio of 20, the R. eutropha Re2133 fermentation process results in 69% w/w of DCW PHA accumulation and consists of HB (78 mol%) and HHx (22 mol%). This shows the feasibility of using coffee waste oil for P(HB-co-HHx) production, as it is a low-cost fatty acid enriched waste material.</P>

Effect of Clay on Thermal, Mechanical and Gas Barrier Properties of Biodegradable Poly(lactic acid)/Poly(butylene succinate) (PLA/PBS) Nanocomposites

Bhatia, A.,Gupta, R.K.,Bhattacharya, S.N.,Choi, H.J. CARL HANSER VERLAG 2010 International polymer processing Vol.25 No.1

Crude oil and stock market co-movement: Evidence from G7 and BRICS nations

( Vaneet Bhatia ),( S K Mitra ) 한양대학교 경제연구소 2018 JOURNAL OF ECONOMIC RESEARCH Vol.23 No.1

This paper examines the dynamic correlation between crude oil and stock market indices of major developed (G7) and emerging (BRICS) economies by analyzing weekly data from January 2000 to March 2017. Results suggest an existence of dynamic correlation between crude oil and stock markets throughout the study period. Results also indicate a considerable increase in dynamic correlation between crude oil and stock markets during the recent crisis. Interestingly, crude oil and indices of developed nations exhibit almost similar co-movements, but the correlation movements between crude oil and the stock indices of BRICS nations show weak homogeneity in the group. The impulse response function in variance (volatility) was employed to investigate the response of stock market indices of G7 and BRICS nations to the shock in the crude oil market and vice versa. Overall, these findings have significant implications for policy makers, investors and portfolio managers.

Seasonal Changes in Concentrations of Proteins and Lipids in Growing Goat Oocytes

Sangha, G.K.,Bhatia, H.,Khera, K.S. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.1

Proteins and lipids not only provide a source of energy to the cell, but also play vital roles in modifying the physical properties and function of the biological membranes. In the present study, we investigated the biochemical constituents, viz. proteins and lipids, in growing oocytes of goat antral follicles during summer and winter seasons. Goat genitalia in phosphate buffered saline (pH 7.4) were brought to the laboratory within one hour of slaughter under aseptic conditions at $37^{\circ}C$. Oocytes were aspirated from normal small (<3 mm in diameter) and large (>3 mm) follicles and pooled for biochemical estimations. A significant increase in the amount of protein and lipid was observed with the growth of the oocyte. The amount of protein varied non-significantly with the season, while the amount of lipid varied significantly. The amounts of phospholipid, cholesterol, free fatty acid, and triglyceride increased with the growth of the oocyte, but no significant effect of season in these constituents was observed. Lysolecithin, sphingomyelin, and sterols were the polar lipids identified in both oocytes prepared from small follicles (small oocytes) as well as large follicles (large oocytes). In addition, the small oocytes also contained phosphatidyl serine, while large oocytes contained phosphatidyl glycerol phosphate and phosphatidyl inositol. Among non-polar lipids, triglycerides and long chain alcohols appear only in small oocytes and not in large oocytes. Monoglycerides, 1,2-diglycerides, 1,3-diglycerides and o-dialkyl glycerol ethers, fatty acids, fatty acid methyl esters, and wax esters were identified in both small and large oocytes. Information on biochemical composition of growing oocytes is relevant to oocyte and embryo competence, culture and cryopreservation.

Approximate Equivalent-Circuit Modeling and Analysis of Type-Ⅱ Resonant Immittance Converters

Mangesh Borage,K. V. Nagesh,M. S. Bhatia,Sunil Tiwari 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.2

Resonant immittance converter (RIC) topologies can transform a current source into a voltage source (Type-I RICs) and vice versa (Type-II RICs), thereby making them suitable for many power electronics applications. RICs are operated at a fixed frequency where the resonant immittance network (RIN) exhibits immittance conversion characteristics. It is observed that the low-frequency response of Type-II RINs is relatively flat and that the state variables associated with Type-II RINs affect the response only at the high frequencies in the vicinity of the switching frequency. The overall response of a Type-II RIC is thus dominated by the filter response, which is particularly important for the controller design. Therefore, an approximate equivalent circuit model and a small-signal model of Type-II RICs are proposed in this paper, neglecting the high-frequency response of Type-II RINs. While the proposed models greatly simplify and speed-up the analysis, it adequately predicts the open-loop transient and small-signal ac behavior of Type-II RICs. The validity of the proposed models is confirmed by comparisons of their results with those obtained from a cycle-by-cycle simulation and with an experimental prototype.

Approximate Equivalent-Circuit Modeling and Analysis of Type-II Resonant Immittance Converters

Borage, Mangesh,Nagesh, K.V.,Bhatia, M.S.,Tiwari, Sunil The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.2

Resonant immittance converter (RIC) topologies can transform a current source into a voltage source (Type-I RICs) and vice versa (Type-II RICs), thereby making them suitable for many power electronics applications. RICs are operated at a fixed frequency where the resonant immittance network (RIN) exhibits immittance conversion characteristics. It is observed that the low-frequency response of Type-II RINs is relatively flat and that the state variables associated with Type-II RINs affect the response only at the high frequencies in the vicinity of the switching frequency. The overall response of a Type-II RIC is thus dominated by the filter response, which is particularly important for the controller design. Therefore, an approximate equivalent circuit model and a small-signal model of Type-II RICs are proposed in this paper, neglecting the high-frequency response of Type-II RINs. While the proposed models greatly simplify and speed-up the analysis, it adequately predicts the open-loop transient and small-signal ac behavior of Type-II RICs. The validity of the proposed models is confirmed by comparisons of their results with those obtained from a cycle-by-cycle simulation and with an experimental prototype.

Application of acetyl-CoA acetyltransferase (AtoAD) in Escherichia coli to increase 3-hydroxyvalerate fraction in poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Jeon, J. M.,Kim, H. J.,Bhatia, S. K.,Sung, C.,Seo, H. M.,Kim, J. H.,Park, H. Y.,Lee, D.,Brigham, C. J.,Yang, Y. H. SPRINGER 2017 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.40 No.5

<P>Polyhydroxyalkanoate (PHA) is a family of biodegradable polymers, and incorporation of different monomers can alter its physical properties. To produce the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) containing a high level of 3-hydroxyvalerate (3HV) by altering acetyl-CoA pool levels, we overexpressed an acetyl-CoA acetyltransferase (atoAD) in an engineered E. coli strain, YH090, carrying PHA synthetic genes bktB, phaB, and phaC. It was found that, with introduction of atoAD and with propionate as a co-substrate, 3HV fraction in PHA was increased up to 7.3-fold higher than a strain without atoAD expressed in trans (67.9 mol%). By the analysis of CoA pool concentrations in vivo and in vitro using HPLC and LC-MS, overexpression of AtoAD was shown to decrease the amount of acetyl-CoA and increase the propionyl-CoA/acetyl-CoA ratio, ultimately resulting in an increased 3HV fraction in PHA. Finally, synthesis of P(3HB-co-3HV) containing 57.9 mol% of 3HV was achieved by fed-batch fermentation of YJ101 with propionate.</P>

Self-powered transparent flexible graphene microheaters

Khan, U.,Kim, T.H.,Lee, K.H.,Lee, J.H.,Yoon, H.J.,Bhatia, R.,Sameera, I.,Seung, W.,Ryu, H.,Falconi, C.,Kim, S.W. Elsevier 2015 Nano energy Vol.17 No.-

Transparent and flexible (TF) microheaters are required in wearable devices, labs-on-chip, and micro-reactors. Nevertheless, conventional microheaters are rigid or opaque or both. Moreover, the resistances of conventional metallic microheaters are too low to be effectively powered by wearable energy harvesters. Here, we demonstrate the first TF microheaters by taking advantage of chemical vapor deposition (CVD)-grown graphene heating tracks and of a hexagonal boron nitride (h-BN) sheet for passivation; the h-BN sheet increases the maximum temperature by ~80%. Our TF microheaters show excellent temperature uniformity and can reach temperatures above 200<SUP>o</SUP>C in just 4s, with power consumption as low as 39mW. Additionally, since the CVD-graphene sheet resistance is orders of magnitude higher than that of typical metallic heaters, our devices can be effectively powered by wearable energy harvesters. As a proof-of-concept, we demonstrate the first self-powered, wearable microheater which achieves a temperature increase of 8<SUP>o</SUP>C when operated by a sound driven textile-based triboelectric nanogenerator. This is a key milestone towards next generation microheaters with applications in portable/wearable personal electronics, wireless health, and remote and mobile environmental sensors.