Efficacy of chitin-PAA-GTMAC gel in promoting wound healing: animal study

Acrylic grafted chitin (chitin-PAA) was modified with glycidyltrimethylammonium chloride (GTMAC) with the aim of promoting wound healing. The chitin-PAA-GTMAC gels with different GTMAC contents were compared with the original chitin-PAA gel and Intrasite gel for their efficacy in deep wound healing of Wistar rats. Four full-thickness wounds were made on the dorsal skin of rats and then each was treated with 4 materials; chitin-PAA, chitin-PAA-GTMAC(1:4), chitin-PAA-GTMAC(1:10) and Intrasite gel. During 18 days of treatment, the wounds were visually observed and calculated for wound size using image analysis program. Skin wound tissues of sacrificed rats were processed for routine histological observation and immunohistochemistry of proliferating cell nuclear antigen (PCNA). The wounds covered with the chitin derivatives either with or without GTMAC showed a significant reduction in wound size in day 9 in comparison with day 12 for those covered with Intrasite gel. The faster rate and the better pattern of epidermal development observed in histological study as well as the higher dermal cell proliferation (PCNA expression) also demonstrated the better efficiency in wound healing of the chitin derivatives than Intrasite. The earliest epidermal development of the wounds treated with chitin-PAA-GTMAC (1:4) among the tested materials suggested the most promising of this material for the treatment of full-thickness open wound.     

Changes in lipid composition and fatty acid profile of Nham,a Thai fermented pork sausage,during fermentation

Changes in lipid composition and fatty acid profile of Nham during fermentation were investigated. Total lipids of Nham were in the range 2–3%. The extracted lipid of initial Nham mix consisted mainly of triglycerides (TG), accounting for more than 75% of the total lipid, followed by phospholipids (PL) and a trace amount of diglycerides (DG) and free fatty acid (FFA). During fermentation, TG, DG and PL decreased with a concomitant increase in FFA, indicating lipolysis of Nham lipids during fermentation. Changes in fatty acids of the total lipids, non-polar and polar lipid fractions were observed during fermentation. In both total and non-polar lipid fractions, the major fatty acids found in a descending order were oleic (C18:1), linoleic (C18:2) and palmitic (C16:0) acids, which together accounted for 90% of the total fatty acids. Increases in fatty acid contents in both total and non-polar lipid fractions, were observed with a corresponding decrease in the quantity of fatty acids of phospholipids. As the fermentation proceeded, peroxide value generally increased while TBARS values decreased. Overall, lipid oxidation in Nham occurred during fermentation but did not cause the objectionable odour and taste in any Nham tested.     

Conversion of Methylesters to Hydrocarbons Over Zn-Modified H-ZSM-5 Zeolite Catalyst

The conversion of methyloctanoate has been studied on Zn- and H-ZSM-5 catalysts. While the addition of Zn has a promoting effect in the aromatization of light alkanes, the effect is much lower when the feed is a methylester. Direct ring closure at the C adjacent to the CO group has been identified.     

Hydrolysis of raw hide using proteolytic enzyme extracted from papaya latex

Crude proteolytic enzyme was extracted from papaya latex using two solvents, water and phosphate buffer pH 6. The yield of extracted enzyme using water as a solvent was similar to that using phosphate buffer. Following the solvent extraction, the extracted enzyme was precipitated in 45 wt% saturated ammonium sulfate solution. The yield and activity of precipitated enzyme considerably decreased. Crude proteolytic enzyme extracted using water as an extracting liquid was, therefore, selected to use in gelatin production from raw hide hydrolysis, comparing to the use of commercial papain. The effects of hydrolysis conditions on gelatin recovery and properties of obtained gelatin were investigated. The optimum conditions for the activities of both crude extracted enzyme and commercial papain were at 75 °C and pH 7. At this condition, the highest percentages of gelatin recovery were obtained from raw hide hydrolysis reactions. The gelatin recovery and gel strength of gelatin obtained from crude extracted enzyme and commercial papain hydrolysis were similar. This proved that crude extracted enzyme from papaya latex could be effectively used in gelatin production, instead of the use of commercial papain, with a comparatively low cost.     

Poly(styrene)‐ and Poly(styrene‐co‐methyl methacrylate)‐graft‐hydrogenated natural rubber latex: Aspect on synthesis,properties, and compatibility

The undesirable properties of natural rubber (NR) can be improved via hydrogenation and graft copolymerization. Hydrogenated NR (HNR) latex was prepared via diimide reduction and then grafted with styrene (ST) or ST/methyl methacrylate (MMA) to form poly(ST)‐graft‐HNR (poly(ST)‐g‐HNR, GHNRS) or poly(ST‐co‐MMA)‐g‐HNR (GHNRSM), respectively. For the grafting of ST monomer onto HNR particles, the %monomer conversion and %grafting efficiency (%GE) were monitored as functions of %hydrogenation, monomer and initiator concentrations, temperature, and time. Under the optimum condition (HNR with 54.3% hydrogenation; 100 phr of ST, 1 phr of initiator at 50°C for 8 h), maximum %conversion and %GE of 44.6% and 36.9%, respectively, were achieved. Thermogravimetric analysis revealed that the HNR grafted with ST or ST/MMA had higher decomposition temperature than an ungrafted one. When these graft products were blended at 10% (w/w) with acrylonitrile‐butadiene‐styrene (ABS) resin, the GHNRS/ABS and GHNRSM/ABS composites exhibited the higher flexural strength and heat aging tolerance compared to the ungrafted HNR/ABS composite. Scanning electron microscopy (SEM) also showed the higher degree of homogeneity at the fractural surface, supporting the higher compatibility between the ABS and the GHNRS or GHNRSM phases in the blends. J. VINYL ADDIT. TECHNOL., 22:100–109, 2016. © 2014 Society of Plastics Engineers     

Gelation Process and Physicochemical Properties of Thai Silk Fibroin Hydrogels Induced by Various Anionic Surfactants for Controlled Release of Curcumin

Hydrogels based on Thai silk fibroin (SF) were prepared by the induction of various anionic surfactants including sodium octyl sulfate (SOS), sodium dodecyl sulfate (SDS), and sodium tetradecyl sulfate (STS), which have a similar chemical structure but different alkyl chain lengths and charges. The effects of anionic surfactant types and their concentrations on the gelation mechanism and time of SF were systematically investigated. We found that SDS and STS that have long alkyl chain lengths and high negative charges could accelerate the gelation of SF to occur within 14–42 min in a concentration-dependent manner. SOS that has a short alkyl chain length and low negative charge slowly induced SF to gel at around 113–144 h. The mechanisms of SF gelation induced by these three anionic surfactants were supposed to be combination of hydrophobic and electrostatic interactions, as well as the self-transition of beta sheets. The SF + STS hydrogels were further employed to encapsulate curcumin for the controlled release application. The SF + 0.09% wt. STS hydrogel encapsulating curcumin showed a slow rate of degradation while sustained the release of curcumin. This hydrogel can be applied as a minimal invasive injectable hydrogel or as a hydrogel for topical treatment of diseases.     

Enzymatic hydrolysis of rawhide using papain and neutrase

Rawhide split was hydrolysed separately by two proteolytic enzymes, papain and neutrase. The effects of enzymatic conditions of the hydrolysis reaction were investigated. During the first 10 min of the enzymatic hydrolysis, the yield of the hydrolysed protein increased sharply, then it slowly increased or became essentially constant due to the limited availability of the substrate. The optimum hydrolysis conditions of papain and neutrase for highest protein yield are at 70 °C, pH 6–7 and 40–50 °C, pH 6–7, respectively. The product from papain hydrolysis is a gelatin with low gel strength and viscosity, while that from neutrase hydrolysis is collagen hydrolysate with viscosity as low as water. This is considered to indicate that longer fragments of protein are obtained from papain hydrolysis than that from neutrase implying different mechanisms of papain and neutrase hydrolysis.     

Modified fuzzy ants clustering approach

Being trapped in local optima within clustering search space currently is nontrivial difficulty. In order to relieve such a difficulty, even using genetic algorithm to optimize the initial clusters for fuzzy c-means is still unsatisfied. Since genetic algorithm intensifies only the current best solution, it will easily gets trapped in local minima. The ant colony system, dissimilarly to genetic algorithm, recognizes that the solutions near the best solution are also good ones and they bring about smoothness of solution. This paper proposes a modified fuzzy ant clustering. Such a presented method is a combination of genetic algorithm, ant colony system and fuzzy c-means. It is employed in creating fuzzy color histogram in image retrieval application. The performance measurement relates to the percentages of accuracy of image retrieval. Experimental results show that the proposed approach yields the best results among others with respect to sensitivity and robustness on dealing with lighting intensity changes, quantization errors, also changes in number of images and in size of color space, even the certain-range variation of a particular parameter of clustering.     

Thermodynamics of the encapsulation by cyclodextrins

Molecular encapsulation on a molecular basis can be performed by cyclodextrins. The inclusion of organic molecules into the interior changes the properties of these molecules, which may be used for a broad variety of applications. The affinity of guest molecules for the cavities of various cyclodextrins depends on the stereochemistry and on the interaction forces of the molecules involved. Calculations of the thermodynamic parameters show that the reaction entropy is highly important for the inclusion reaction. Completely different reaction mechanisms are observed for various types of cyclodextrins as some of these reactions show enthalpy–entropy compensation. Others are supported by the reaction entropy or are even entropically controlled. Protonation and deprotonation reactions contribute significantly to the inclusion reaction, as first of all the solubility of the compounds in water is strongly influenced by the acidity of the solution, and, moreover, all tautomeric forms of the compounds show different affinities to various cyclodextrins. Copyright © 2006 Society of Chemical Industry     

Room-temperature multiferroicity in NiFe2O4 and its magnetoelectric coupling intensified through defect engineering

The well-known ferromagnetic oxide, NiFe₂O₄, was studied as a potential candidate for room-temperature Type II magnetoelectrics. A spin canting as one of the essential requirements for Type II multiferroics was induced by breaking the stoichiometry, that is, intentionally subtracting Fe ions. We observed that Fe ions were first subtracted exclusively from the tetrahedral sites, leading to an increase in the magnetoelectric coupling owing to an increasing degree of spin canting. The enhancement in the magnetoelectric coupling culminated beyond the subtraction level of ~30 at.%, at which Fe ions started to be removed from the octahedral sites. Alongside, we observed that the subtraction of Fe ions gives rise to a ferroelectricity due to the formation of defect complexes that establish an internal bias field.