Production of medium chain saturated fatty acids with enhanced antimicrobial activity from crude coconut fat by solid state cultivation of Yarrowia lipolytica

Fatty acids profiles and antimicrobial activity of crude coconut fat hydrolysates obtained in solid-state cultivation system with a selected yeast strain Yarrowia lipolytica RO13 were performed. A preliminary step regarding extracellular lipase production and solid state enzymatic hydrolysis of crude fat at different water activity and time intervals up to 7 days was also applied. Gas chromatography–mass spectrometry analysis was used for quantification of medium chain saturated fatty acids (MCSFAs) and the results revealed a higher concentration of about 70% lauric acid from total fatty acids. Further, antimicrobial activity of fatty acids against some food-borne pathogens (Salmonella enteritidis, Escherichia coli, Listeria monocytogenes and Bacillus cereus) was evaluated. The minimum inhibitory concentration of the obtained hydrolysates varied from 12.5 to 1.56 ppm, significantly lower than values reported in literature. The results provide substantial evidence for obtaining biopreservative effects by coconut fat enzymatic hydrolysis.     

Determination of chloramphenicol in shrimp by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS).

A liquid chromatographic method with electrospray ionization tandem mass spectrometric (LC-ESI-MS-MS) detection and identification is described for the determination of chloramphenicol (CAP) in shrimp tissue. Homogenized shrimp samples were extracted by liquid-liquid extraction using ethyl acetate. d5-Chloramphenicol (5D-CAP) was used as the internal standard. Data acquisition was in negative-ion multiple reaction monitoring (NMRM) mode using three transition reactions for CAP (m/z 321 --> 152, m/z 321 --> 257 and m/z 321 --> 194) and two for d5-chloramphenicol (m/z 326 --> 262 and m/z 326 --> 157). Method validation was carried out according to European Commission decision 2002/657/EC. The calibration curve was linear in the range 0.10-2.00 microg l(-1), with typical r2 > 0.99. The decision limit (CC alpha) and detection capability (CC beta) were 0.06 and 0.10 microg kg(-1), respectively. There was no influence of the matrix on the determination of chloramphenicol.     

Self-Healing Dynamic Polymeric Systems

The concept of self-healing has created a paradigm shift in the development of a new kind of responsive polymeric materials, which have traditionally been used in a passive role. Inspired by nature, the advancements made in this nascent field of research have given materials the ability of not only sensing damage but also responding and mending themselves in an appropriate manner. Self-healing in polymers can be autonomous, without the need for human intervention, or nonautonomous, requiring some form of external stimulus. The latter type involves the incorporation of dynamic bonds within the polymeric system, giving the ability to heal multiple times. This minireview discusses some of the prominent self-healing polymeric systems that harness different dynamic bond chemistries, with the aim of highlighting the potential of dynamic bonds to prepare such advanced materials.     

Fermentative hydrogen production - An alternative clean energy source

Hydrogen generation from wastewater is one of the promising approaches through biological route. So, exploitation of wastewater as substrate for hydrogen production with concurrent wastewater treatment is an attractive and effective way of tapping clean energy from renewable resources in a sustainable approach. In this direction, considerable interest is observed on various biological routes of hydrogen production using bio-photolysis, photo fermentation and heterotrophic dark fermentation process or by a combination of these processes. Therefore, in this communication, utilizing industrial wastewater as primary substrate for dark fermentation process is reviewed and different parametric aspects associated with this sustainable approach for better energy production is discussed. The industrial wastewaters that could be the source for bio hydrogen generation, such as rice slurry wastewater, food and domestic wastewaters, citric acid wastewater and paper mill wastewater, are also discussed in this article.     

FT‐IR microscopic studies on coupling agents: treated natural fibres

Natural fibres (sisal) were treated with various coupling agents such as organosilane, zirconate, titanate and N‐substituted methacrylamide. The nature of the adsorbed chemical species on the fibre surfaces was analysed by Fourier transform infrared microscopy (FT‐IR). The presence of precipitated oligomers on the surface was confirmed by the appearance of hydrogen‐bonded carbonyl group and unsaturation bands. The results showed an irregular physisorption/chemisorption of coupling agents, their penetration beyond the surface, and a decrease in the hydrophilicity of fibres. SEM and dynamic contact angle studies on the fibres supported these findings. FT‐IR microscopy in its reflectance mode was more effective in ascertaining the chemical nature and structure of adsorbed layers onto sisal fibre surfaces compared with DRIFT and transmission spectroscopy. The difference in the properties of untreated and chemically treated fibres has also been verified in the polymer composites. © 2000 Society of Chemical Industry     

The kinetic study for asymmetric membrane formation via phase-inversion process

The kinetics of membrane formation by phase inversion was studied emphasizing the rate of solvent diffusion from a polymer solution during the phase separation. Diffusional behavior of the solvent can be considered Fickian. Membrane morphologies were shown to be strongly dependent on the rate of solvent diffusion, indicating that mass-transfer rates of solvent and nonsolvent during phase separation are crucial for determining the final membrane structure for the following system: polysulfone (polymer), dimethyl acetamide (solvent), and ethanol (gelation medium). Specific reference to the mechanism of macrovoid formation was explored. Macrovoid formation was found to be proportional to the square root of time, suggesting that it is governed by a diffusion process. In addition, latex particles of coagulated polymer formed by the nucleation and growth of a concentrated polymer phase was observed inside the macrovoids. Such a result implies that the macrovoids grow by a diffusive flow which results from the growth of the polymer lean phase during binodal decomposition. © 1996 John Wiley & Sons, Inc.     

Smart Vitamin Micelles as Cancer Nanomedicines for Enhanced Intracellular Delivery of Doxorubicin

Chemotherapy is one of the most effective treatments for cancer. However, intracellular delivery of many anticancer drugs is hindered by their hydrophobicity and low molecular weight. Here, we describe highly biocompatible and biodegradable amphiphilic vitamin conjugates comprising hydrophobic vitamin E and hydrophilic vitamin B labeled with dual pH and glutathione-responsive degradable linkages. Vitamin-based micelles (vitamicelles), formed by self-assembly in aqueous solutions, were optimized based on their stability after encapsulation of doxorubicin (DOX). The resulting vitamicelles have great potential as vehicles for anticancer drugs because they show excellent biocompatibility (>94% after 48 h of incubation) and rapid biodegradability (>90% after 2.5 h). Compared with free DOX, DOX-loaded vitamicelles showed a markedly enhanced anticancer effect as they released the drug rapidly and inhibited drug efflux out of cells efficiently. By exploiting these advantages, this study not only provides a promising strategy for circumventing existing challenges regarding the delivery of anticancer drugs but also extends the utility of current DOX-induced chemotherapy.     

Magnetically tunable microstrip resonator based on polycrystallineferrite

A conventional microstrip ring resonator consisting of a polycrystalline ferrite substrate is demonstrated. This resonator produces improved tunability compared with other available versions. Resonators with tunability approaching 31% at a minimum insertion loss of 11.17 dB in a magnetic field of 3 kG applied longitudinally along wave propagation have been demonstrated using LiZiTi ferrite composition. Tunability of 31% is the best reported for any tunable structure     

Preparation of mechanically strong poly (ether block amide)/Mercaptoethanol breathable membranes for biomedical applications

Poly (ether block amide) (PEBA) was modified with Mercaptoethanol (ME) to introduce crosslinks in its polymeric structure and emphasis was laid on obtaining non-porous breathable membranes with improved mechanical properties which can be used for various biomedical applications. Pebax MH 1657 (mentioned as PEBA throughout the text) was cast polymerized with ME and the effect of ME on the properties of the membranes (such as water absorption, permeability, tensile strength, elongation & tear strength) was studied. Fourier Transform Infrared Spectroscopy- Attenuated Total Reflectance (FTIR-ATR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG) techniques were used to characterize the membranes. Different amount of ME (10 to 40% w/w) was added to PEBA and 30% of ME was found to be most effective in increasing the mechanical properties of the membrane. Sulfhydryl group played an important role in enhancing mechanical strength of the membranes. PEBA/ME based non porous breathable membrane with excellent mechanical strength is a novel material that can be used for various biomedical applications.     

Polymer-polymer interaction parameter determined by inverse gas chromatography

Inverse gas chromatography was employed to determine the apparent polymer-polymer interaction parameter χ′_23,app for the following blends using them as binary stationary phases: poly(vinyl acetate)-poly(n-butyl methacrylate) at 100 and 120°C, poly(vinyl acetate)-atactic poly(vinyl isobutyl ether) at 70°C, and poly(n-butyl methacrylate)-atactic poly(vinyl isobutyl ether) at 70°C. The interaction parameter χ′_23,app depended significantly on the chemical nature of the solvent (probe) used and the composition of the stationary phase. The lowest values of χ′_23,app were obtained when aromatic and chlorinated-alkane probes were eluted on stationary phases having weight fractional compositions of the component polymers in the range 0.4–0.6. The results predict a better compatibility for poly(n-butyl methacrylate)-atactic poly(vinyl isobutyl ether) than for the other blends.