Thermal characteristics and corrosion behaviour of Mg–xZn alloys for biomedical applications

The thermal parameters of Mg–xZn cast alloys with 0·5–9 wt% Zn were evaluated by using computer aided cooling curve thermal analysis (CA–CCTA), whereas the corrosion behaviour was investigated by potentiodynamic polarization and immersion tests. Thermal analysis results revealed that the dendrite coherency temperature (T _DCP ) decreased from 642·2 to 600 °C with the addition of Zn from 0·5 to 9 wt%. The liquid fraction at coherency point ( ${f}_{ L}^{ DCP}$ ) increased by 72% when Zn was increased up to 9 wt%. MgZn intermetallic phase was observed in samples with <3 wt% Zn. At higher percentages of Zn, the Mg ₅₁Zn ₂₀ intermetallic phase was also detected in addition to α-Mg and MgZn by first derivative cooling curves under non-equilibrium solidification. All these phases were observed along the grain boundary when Zn was rejected from the solid/liquid interface and enriched in the triple conjunction of grain boundary. The grain size decreased from 185·2 to 71·5 μm when Zn content was increased. The addition of Zn content had a significant effect on the corrosion rate and the corresponding mechanisms. The corrosion rate decreased from 2·1 to 1·81 mmpy as Zn content increased from 0·5 to 3 wt%; afterwards, however, this value increased with further increase of Zn. Mg–3Zn also had the lowest degradation rate and highest corrosion resistance which can be fully utilized for biodegradable orthopedic applications.     

INHIBITION OF SOME FOODBORNE BACTERIA BY ALCOHOL EXTRACT OF SUMAC (RHUS CORIARIA L.)

The inhibitory effect of alcohol extract of sumac (Rhus coriaria L.) was investigated at concentrations of 0.1, 0.5, 1.0, 2.5 and 5.0% (w/v) on the growth of 12 bacterial strains (6 Gram positives and 6 Gram negatives), mostly foodborne including pathogens. Minimal inhibitory concentration of the spice for each test organism was also studied by observing their growth on Nutrient Agar containing the spice extract at various incremental levels equivalent to 100–5000 mg/L of spice. Alcohol extract of sumac was found to be effective against all the test organisms, Gram positives being more sensitive than Gram negatives. Among the Gram positives, Bacillus species (B. cereus, B. megaterium, B. subtilis and B. thuringiensis) were found to be the most sensitive, surviving up to only 500 mg/L of the spice, followed by Staphylococcus aureus (1000 mg/L), whereas Listeria monocytogenes was found to be the most resistant, surviving up to 1500 mg/L. Of the Gram negative bacteria, Salmonella enteritidis and Escherichia coli type I were found to be more resistant, surviving up to 3000 mg/L of the spice, followed by E. coli O157:H7 (2500 mg/L), Hafnia alvei (2000 mg/L), Proteus vulgaris (1500 mg/L) and Citrobacter freundii (1000 mg/L). Significant differences (P < 0.01) were found among bacterial strains and between the extracts of unripened and ripened sumac samples, with ripened being more effective against all of the bacteria tested.     

Identification of potential inhibitors for Sterol C-24 reductase of <i>Leishmania donovani</i> through virtual screening of natural compounds

Leishmaniasis is a vector-borne parasitic neglected tropical disease caused by a group of about 30 differentspecies of the genus Leishmania. It is transmitted by the bite of female phlebotomies sand fly. Three main clinicalmanifestations of leishmaniasis include cutaneous, visceral, and mucocutaneous leishmaniasis. Visceral leishmaniasis(VL) caused by Leishmania donovani, is an infection of reticuloendothelial system and fatal if untreated. Cholesterol,a sterol that is prominent in the mammalian cell membranes whereas stigmasterol and ergosterol are more prevalentin plants, yeast, and protozoa, respectively. Ergosterols which is absent in human being, is an important constituent ofparasite membrane. Sterol C-24 reductase (LdSR) enzyme catalyzes the final step in the ergosterol biosynthesis pathway.The inhibition of biosynthesis of ergosterol may lead to decreased cell viability and growth. Here, we performed themolecular docking-based virtual screening of a library of natural ligands against LdSR to identify a potential inhibitor tofight leishmaniasis. Capsaicin, prenyletin, flavan-3-ol, resveratrol, and gingerol showed the top binding affinity towardsLdSR. Based upon ADME properties and bioactivity score, gingerol showed the best lead-likeness and drug-likenessproperties. Hence, we further annotated its leishmanicidal properties. We found that gingerol inhibited the growth andproliferation of promastigotes as well as intra-macrophagic amastigotes. Gingerol exerted its antileishmanial actionthrough the induction of reactive oxygen species (ROS) in concentration-dependent manner. Gingerol induced ROS ledto apoptosis. Overall, this study described that gingerol would act as possible inhibitor to LdSR.     

EFFECTS of SEMPERFRESH and JONFRESH FRUIT COATINGS ON POSTSTORAGE QUALITY of "SATSUMA" MANDARINS

Mandarins were coated with Semperfresh^TM and Jonfresh^TM edible coatings. the weight gain of mandarins after application of Jonfresh and Semperfresh coatings was 0.8% and 0.6% respectively. Weight loss, respiration rate, ascorbic acid, soluble solids (brix) and acidity changes of coated mandarins were compared with uncoated mandarins during storage at 20C and 40% RH for 4 weeks. Semperfresh^TM and Jonfresh^TM coatings delayed the ripening of mandarins. Both of the coatings were effective to reduce the change of ascorbic acid, soluble solids, titratable acidity and respiration rate. But Jonfresh^TM was determined to be most efficient coating for reduction of weight loss.     

面向自然语言信息处理的维吾尔语名词形态分析研究

名词是人类语言中的基本词类之一。维吾尔语是一种形态变化很复杂的语言,其中名词是一种形态变化复杂的词类。因此名词的形态分析研究无论在语法研究还是在语言信息处理中都非常重要。本文对维吾尔语名词的形态变化(名词的数、人称、格等语法范畴)进行了形式化的描述和分析。指出了维吾尔语名词的基本形态参数,总结出参数的组配规律并统计了其类型,探索了维吾尔语名词的削尾方法。这些工作将为维吾尔语名词形态处理提供有效的方法和新的思路。     

USE OF NATURAL PLANT EXTRACTS IN BATTER COATING OF SHRIMP AND THEIR EFFECTS ON THE QUALITY OF SHRIMP DURING FROZEN STORAGE

Commercial extracts of garlic, tomato and grape seed were separately added into batter coating formulation. Quality changes of coated shrimps were investigated during frozen storage. Samples with added extracts had higher pH values than the control group. Higher total volatile basic nitrogen value was found in the sample with tomato extract compared with extract containing garlic and grape seed extracts. The lowest trimethylamine concentration was found in the sample containing garlic extract. Although the most effective extract in retarding oxidation was grape seed extract, garlic extract had protective effect against spoilage. The lowest scores for sensory appearance, odor and taste were found in samples with grape seed extract. It was concluded that use of plant extracts in the coating mixture affected the quality of shrimp during frozen storage. It was also found that the sample with garlic extract was the best product in terms of sensory characteristics.

PRACTICAL APPLICATIONS

Shrimp is a perishable product and it is important to extend its shelf life. Battered products have gained a grown consideration in the field of ready to eat seafood. Most of researches on batter-coated food products have focused on reducing the amount of fat absorbed during frying and improving rheological properties. There is no study on addition of antioxidative, antibacterial agents to coating mix. This is a new approach to improve the quality and shelf life.