Effects of carbon source and metabolic engineering on butyrate production in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Butyrate was produced in recombinant Escherichia coli strains by applying metabolic engineering strategies. The genes for producing butyrate were cloned from Clostridium acetobutylicum and then expressed in E. coli. To study important factors for improving the productivity of butyrate, we deleted pta and ptsG genes in E. coli and compared the effects of these gene deletions in E. coli B and K strains. The effect of carbon sources, glucose and glycerol, was also compared. A significant improvement of butyrate production was made when glycerol was used as a carbon source, resulting in 0.56 g/l of butyrate in LB medium with 1% (v/v) glycerol.     

Tropolone-Conjugated DNA: A Fluorescent Thymidine Analogue Exhibits Solvatochromism,Enzymatic Incorporation into DNA and HeLa Cell Internalization

Tropolone is a non-benzenoid aromatic scaffold with unique photophysical and metal-chelating properties. Recently, it has been conjugated with DNA, and the photophysical properties of this conjugate have been explored. Tropolonyl-deoxyuridine (tr-dU) is a synthetic fluorescent DNA nucleoside analogue that exhibits pH-dependent emissions. However, its solvent-dependent fluorescence properties are unexplored owing to its poor solubility in most organic solvents. It would be interesting to incorporate it into DNA primer enzymatically. This report describes the solvent-dependent fluorescence properties of the silyl-derivative, and enzymatic incorporation of its triphosphate analogue. For practical use, its cell-internalization and cytotoxicity are also explored. tr-dU nucleoside was found to be a potential analogue to design DNA probes and can be explored for various therapeutic applications in the future.     

Hydrotropic effect and thermodynamic analysis on the solubility and mass transfer coefficient enhancement of ethylbenzene

Concentrated aqueous solutions of a large number of hydrotropic agents, urea, nicotinamide, and sodium salicylate, have been employed to enhance the aqueous solubilities of poorly water soluble organic compounds. The influence of a wide range of hydrotrope concentrations (0–3.0mol·L^?1) and different system temperatures (303–333 K) on the solubility of ethylbenzene has been studied. The solubility of ethylbenzene increases with increase in hydrotrope concentration and also with system temperature. Consequent to the increase in the solubility of ethylbenzene, the mass transfer coefficient was also found to increase with increase in hydrotrope concentration at 303 K. The enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, is reported for both solubility and mass transfer coefficient of ethylbenzene. The Setschenow constant, K _s , a measure of the effectiveness of a hydrotrope, was determined for each case. To ascertain the hydrotropic aggregation behavior of ethylbenzene, thermodynamic parameters such as Gibb’s free energy, enthalpy, and entropy of ethylbenzene were determined.     

Impacts of high-speed waterjets on web structures

Hydroentangling, where a fabric is formed by striking of fine, closely spaced, high speed waterjets, is one of the fastest growing bonding methods in the nonwoven industry. Softness, drape, conformability, and relatively high strength are the major characteristics that make this bonding technology unique. Despite the method appeal, few understand the impact of waterjet on fabric structures. The primary function of waterjet is to produce fiber entangling, which induces web integrity. In this paper, we have analyzed the interaction of waterjets on web structures to provide a better understanding of the hydroentangling mechanism. We have successfully visualized and analyzed structures of entangled regions through 2D and 3D imaging techniques. The influence of water-jet pressure, jet diameter, and number of jets on hydroentangled web structures is reported.     

Quality changes in trans and trans free fats/oils and products during frying

The physico-chemical changes occurring during simulated frying conditions at 180 °C for 24 h in trans free speciality fat, trans rich vanaspati and PUFA rich sunflower oil were evaluated. The samples became darker, the polar components and viscosity increased as the time of heating increased. The oxidative stability as determined by peroxide, anisidine values and TOTOX number, increased, whereas the total unsaturated fatty acids and iodine value decreased with time of heating in all the samples. The trans free speciality fat was as stable as vanaspati showing similar quality parameters, while sunflower oil showed a higher degree of deterioration. The layered fat used for traditional products such as Chiroti dough consisted 14% trans fatty acids (TFA), which was reduced to 4–7%, and correspondingly 18:2 was increased in the product upon frying in sunflower oil. Accordingly, trans fatty acids increased in the medium from 0 to 7.5%. Chiroti when fried in vanaspati with TFA 18%, their content in both products (16%) and in medium (17%) remained similar.     

Antioxidant and anticancer activities of 8-hydroxypsoralen isolated from wampee [Clausena lansium (Lour.) Skeels] peel

Fruits of wampee [Clausena lansium (Lour.) Skeels] contain a significant amount of coumarins with many health benefits. The activity-guided separation of an ethyl acetate-soluble fraction on a polyamide column followed by silica gel column and high performance liquid chromatography (HPLC) preparation afforded a pure compound, which was identified to be 8-hydroxypsoralen based on the ¹H, ¹³C NMR (nuclear magnetic resonance), and ESI-MS (electrospray ionisation mass spectrometric) analysis. This isolate exhibited good scavenging activities against DPPH radical and superoxide anion as well as significant reducing power. It also showed potent proliferation inhibitory activity against human hepatocellular liver carcinoma cell line (HepG2), human lung adenocarcinoma epithelial cell line (A549) and human cervical carcinoma cell line (HELA). This is the first report on the antioxidant and cytotoxic properties of C. lansium fruit extract. The food and pharmaceutical industry could be benefited by the usage of this extract containing this constituent.     

Development of high temperature material for cellular ceramic regenerative storage heater

Ceramic Regenerative Storage Heater (RSH) is the preferable solution to provide clean hot air in Hypersonic Wind Tunnel (HWT) and Scramjet Test facilities to prevent the liquefaction of air during expansion in the high Mach number nozzles. Selection of the heater storage material for such operational requirements is a challenging task. As per the theoretical background; alumina, zirconia or mullite compositions have the capability to withstand at such high operating conditions. In the current study, a series of experiments were carried out to estimate the thermal characteristics of the material. This paper highlights the simplified approach by combining theoretical and experimental methods for economic (reduced time and cost) selection process of high temperature material. The desired material must possess good thermal shock resistance and low dust generation characteristics. Al₂O₃ and SiO₂ based matrix composition fused in a transcrystalline phase exhibits significant improvement on the overall material integrity. Several Al₂O₃ and SiO₂ matrix compositions were examined and the final matrix composite ratio of 90% of Al₂O₃ and 10% of SiO₂ is considered as the desired candidate material. The ceramic matrix was sintered at a temperature of 2123?K, under the specific pressure of 1400?kg/cm² for a period of 2?h, at a heating rate of 3.5?°C/min. The results of the thermal shock tests on various samples are presented. To improve the anti-dust characteristics, the final samples were coated with fine particles (5?µm) of Al₂O₃ and SiO₂ matrix. Based on the experimental evaluation, Al₂O₃ and SiO₂ fused matrix composition found to be meeting all the requirements of high temperature storage material.     

Updates on understanding of probiotic lactic acid bacteria responses to environmental stresses and highlights on proteomic analyses

Probiotics are defined as live microorganisms that improve the health of the host when administered in adequate quantities. Nonetheless, probiotics encounter extreme environmental conditions during food processing or along the gastrointestinal tract. This review discusses different environmental stresses that affect probiotics during food preparation, storage, and along the alimentary canal, including high temperature, low temperature, low and alkaline pH, oxidative stress, high hydrostatic pressure, osmotic pressure, and starvation. The understanding of how probiotics deal with environmental stress and thrive provides useful information to guide the selection of the strains with enhanced performance in specific situations, in food processing or during gastrointestinal transit. In most cases, multiple biological functions are affected upon exposure of the cell to environmental stress. Sensing of sublethal environmental stress can allow for adaptation processes to occur, which can include alterations in the expression of specific proteins.     

Study on the DC supply and charging effect on the growth of carbon nanotubes and their electrochemical properties

Journal of Materials Science: Materials in Electronics - Preparation of chirality-defined few-walled CNT (FWCNT) is one of the major challenges in the carbon nanotube (CNT) fields. In the last two...     

Advanced process modeling at the BCL smelter: Improving economic and environmental performance

Since 1973 Bamangwato Concessions Limited (BCL) has operated a nickel-copper smelter in Selebi-Phikwe, Botswana. The smelter treats concentrates from local mines and various custom feed concentrates. The nickel throughput capacity of this smelter is constrained by a low nickel feed grade in its primary BCL concentrate. BCL contracted Xstrata Process Support (XPS) to assist in identifying key economic drivers to maximize revenue-generating opportunities. After the disclosure of essential BCL plant performance data XPS developed and utilized advanced metallurgical modeling techniques to identify production bottlenecks, calculate Ni, Cu, and Co recoveries, manage the slag volumes, increase the custom feed capacity, and perform various feasibility analyses for key unit process operations in the BCL smelter. The methodology for developing the process model and its application in contributing to the economic bottom line are outlined in this paper.