Defense role of the cocoon in the silk worm Bombyx mori L

Silk from the domesticated silk worm Bombyx mori procures foreign body response naturally, so it has been utilized as a biomaterial for decades. In India the prime focus of the sericulture industry is to improve silk production with high quality silk. Naturally, the silk worm builds its cocoon not only with silk proteins, but also with antimicrobial proteins to avoid infection since the cocoon is non-motile and non-feeding. The aim of the present study is to elucidate the antimicrobial proteins that persist in the cocoon of the silk worm Bombyx mori. At the pupal stage, the silk worm cocoon shell extract was prepared from the day of pupation (P0) to the day of natural rupture of the cocoon for the eclosion of moth (NR). Using the cocoon shell extract a microbial susceptibility test was performed by the disc diffusion method against the microbes Escherchia coli, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The development of a zone of inhibition against the microbes confirmed the presence of antimicrobial/immunogenic activity of the cocoon shell extract. For further analysis, the cocoon shell extract was subjected to 7-15% sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE). The protein profile of the cocoon extract revealed the coomassie blue stained bands resolved from the 150-15 kDa molecular range. Interestingly, a polypeptide localized at around 29 kDa showed remarkable expressional changes during the development of pupa. To characterize the 29 kDa protein, it was eluted from the gel, digested with trypsin and analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The trypsin-digested peptide peaks were analyzed through MASCOT and peptides were matched with the NCBI nr database. The peptides were very well matched with the 18 wheeler protein, which is reported to be responsible for innate immunity, belonging to the Toll family in insects and responsible for cellular mediated immunity.     

Facile syntheses of 3-halo and mixed 3,5-dihalo analogues of N-acetyl-l-tyrosine via sulfonic acid-catalysed regioselective monohalogenation

The combination of catalytic amounts of p-toluenesulfonic acid and 1 equiv of N-halosuccinimide afforded highly selective ring-halogenation of N-acetyl-l-tyrosine, furnishing either N-acetyl-3-halo-l-tyrosine analogues or mixed 3,5-dihalo derivatives in a one-pot reaction with excellent yields at room temperature.     

Effect of Synthetic Routes on the Catalytic Activity of FePO4 for p-Nitrophenol Reduction

Kinetics and Catalysis - The catalytic application of FePO4 synthesized by various chemical routes for the conversion of p?nitrophenol to p-aminophenol was investigated. The catalyst...     

High aspect ratio nanocellulose from an extremophile spinifex grass by controlled acid hydrolysis

During the last two decades, work surrounding the preparation of a vast array of cellulose nanomaterials from both wood and non-wood based sources has steadily intensified. This study reports on the isolation of high aspect ratio nanocellulose from an arid grass source commonly called “spinifex”, Triodia pungens, via an optimised sulfuric acid hydrolysis protocol. The unique attributes of T. pungens have enabled pulping and bleaching under milder conditions than used in typically reported protocols, followed by relatively easy deconstruction into nanofibres with an unprecedentedly high aspect ratio. Hydrolysis of bleached T. pungens under these optimised processing conditions has yielded nanocellulose with a very high aspect ratio of 144 (average dimensions of 3.45 ± 1 nm × 497 ± 106 nm), a crystallinity of 73% and a production yield of 42%. Based on the spectroscopic and X-ray scattering analyses, an unusually high content of hemicellulose (42%) is correlated with both the ease of deconstruction and the retention of nanocellulose length. This high hemicellulose content also appears to give rise to a lower transverse stiffness than previously-reported values for wood sources.     

Stabilization of γ-sterilized biomedical polyolefins by synergistic mixtures of oligomeric stabilizers. Part II. Polypropylene matrix

In our previous study we have found the synergistic combinations of stabilizers which follow different mechanisms of stabilization and are approved for food contact and biomedical applications. The present attempt is to test the potentials of those systems in stabilizing γ-sterilized isotactic polypropylene (i-PP). Isotactic polypropylene was melt-mixed with hindered amine stabilizers (HAS), phenolic antioxidants and organo-phosphites (hydroperoxide decomposer) and sterilized with different doses of γ-radiation. Stabilization was monitored in terms of changes in the functional groups (oxidation products), tensile properties, yellowing and surface morphology by FTIR spectroscopy, Instron, colorimetry (reflectance) and scanning electron microscopy (SEM), respectively. The trend in stabilizing the efficiency of binary (1:1), ternary (1:1:1) and quaternary (1:1:1:1) additive systems was confirmed by comparing the stabilizing efficiency of mixtures with and without phenol system as well as with their counter parts of EP copolymer matrix. The binary system of secondary HAS and tertiary HAS, has shown antagonistic effect of stabilization whereas their combination with organo-phosphite has exhibited synergistic effect even at higher doses of γ-sterilization. Due to the oxidation of hindered phenol, phenol systems have shown discoloration and it was reduced by mixing with secondary HAS, tertiary HAS and organo-phosphite. The response of the stabilizer systems is better to ethylene-propylene (EP) copolymer than to i-PP in terms of stabilization.     

Photo‐stabilization of EPDM–clay nanocomposites: effect of antioxidant on the preparation and durability

The present study is to examine the photo‐stabilization effect of an antioxidant on the photo‐oxidation of ethylene‐propylene‐diene monomer (EPDM)–clay nanocomposites. During the preparation of EPDM–clay nanocomposites via melt processing antioxidants are usually incorporated along with clay, which allows phenolic antioxidant molecules to get adsorbed onto acidic clay platelets and their interaction with metallic impurities reduces the stabilizing efficiency of the antioxidant. The nanocomposites were obtained by solution dispersion followed by melt compounding of EPDM and organophilic montmorillonite (OMMT). The samples were characterized by conventional tools such as X‐ray diffraction (XRD), Fourier Transform Infra Red (FT‐IR) spectroscopy, and thermo‐gravimetric analysis (TGA). It was found, upon photo‐irradiation (λ > 290 nm) studies by following the changes in functional groups and surface morphology, that photo‐degradation was lowered by the antioxidant and the efficiency of the antioxidant could be improved by initial incorporation of antioxidant in the EPDM matrix. In EPDM–clay nanocomposites, a stabilizing activity of the antioxidant was observed above some threshold concentration of the antioxidant. The relationship between the nanoclay reinforcement and stabilizing efficiency in terms of photo‐oxidation and surface morphology for their applicability are discussed. The methodology adopted for this study is also justified through our observation. Copyright © 2007 John Wiley & Sons, Ltd.     

Biodegradation of packaging materials: composting of polyolefins

The compostability of LDPE, PP and heterophasic E-P Copolymers was studied for 5 months under normal and accelerated composting environments. Bio-susceptibility of pre-UV (290 nm) treated films (∼ 100μm, 5 X 5 cm) was measured by monitoring the weight loss, intrinsic viscosity [η], chain scission, functional group evolution (FT-IR) and surface morphology (SEM). It was found that with the increasing time of UV treatment, weight loss was increased in compost. Almost linear decrease in [η] was observed for irradiated and composted samples. The temperature of compost and extra addition of thermophilic microbes significantly influenced the biodegradation. In general, it was concluded that the composition of copolymer markedly affected the compostability and increased ethylene content, slowed down the microbial activity.