Arsenic accumulation and metabolism in rice (Oryza sativa L.)

The use of arsenic (As) contaminated groundwater for irrigation of crops has resulted in elevated concentrations of arsenic in agricultural soils in Bangladesh, West Bengal (India), and elsewhere. Paddy rice (Oryza sativa L.) is the main agricultural crop grown in the arsenic-affected areas of Bangladesh. There is, therefore, concern regarding accumulation of arsenic in rice grown those soils. A greenhouse study was conducted to examine the effects of arsenic-contaminated irrigation water on the growth of rice and uptake and speciation of arsenic. Treatments of the greenhouse experiment consisted of two phosphate doses and seven different arsenate concentrations ranging from 0 to 8 mg of As L(-1) applied regularly throughout the 170-day post-transplantation growing period until plants were ready for harvesting. Increasing the concentration of arsenate in irrigation water significantly decreased plant height, grain yield, the number of filled grains, grain weight, and root biomass, while the arsenic concentrations in root, straw, and rice husk increased significantly. Concentrations of arsenic in rice grain did not exceed the food hygiene concentration limit (1.0 mg of As kg(-1) dry weight). The concentrations of arsenic in rice straw (up to 91.8 mg kg(-1) for the highest As treatment) were of the same order of magnitude as root arsenic concentrations (up to 107.5 mg kg(-1)), suggesting that arsenic can be readily translocated to the shoot. While not covered by food hygiene regulations, rice straw is used as cattle feed in many countries including Bangladesh. The high arsenic concentrations may have the potential for adverse health effects on the cattle and an increase of arsenic exposure in humans via the plant-animal-human pathway. Arsenic concentrations in rice plant parts except husk were not affected by application of phosphate. As the concentration of arsenic in the rice grain was low, arsenic speciation was performed only on rice straw to predict the risk associated with feeding contaminated straw to the cattle. Speciation of arsenic in tissues (using HPLC-ICP-MS) revealed that the predominant species present in straw was arsenate followed by arsenite and dimethylarsinic acid (DMAA). As DMAA is only present at low concentrations, it is unlikely this will greatly alter the toxicity of arsenic present in rice.     

Mass-rearing of the redlegged ham beetle, Necrobia rufipes De Geer (Coleoptera: Cleridae) for laboratory research

A new protocol for mass-rearing the redlegged ham beetle, Necrobia rufipes De Geer, in the laboratory is described, that facilitates the production of large numbers of insects with minimal handling. A culture medium comprised of finely ground (150 μm) dried fish, dry dog food and pieces of dried cured ham was tested on N. rufipes. This rearing medium produced significantly larger population numbers when compared with a range of published and unpublished methods. When reared on this medium with initial colonies of 200 mixed sex adult beetles, there was more than a three-fold increase in N. rufipes adult populations from the original numbers over a 7-8 week period. This simple procedure minimizes cannibalism as the larvae were shifted into glass vials for pupal cell formation.     

中孟在校青年男子体型对比分析

为分析中孟在校青年男子体型区别,对孟加拉和中国在校青年男子的整体和局部体型进行对比和分类分析。运用手工测量及三维测量法获取中国与孟加拉各200名在校青年男子的相关体型参数,对比分析孟加拉与中国在校青年男子的整体和局部体型。在整体体型方面,分析了两国在校青年男子于国家标准及形态整体特征上的异同点;在局部体型方面,针对肩部、胸部和腰臀部3个人体主要特征部位进行分类,分别将各个部位的体型聚类成3类进行对比分析。研究表明:中孟在校青年男子体型差异较大,中国在校青年男子整体瘦长、整体曲线明显、肩部较宽、胸部线条弧度较大、臀部挺翘;孟加拉在校青年男子大部分属于均匀凸腹体型,整体轮廓线条平缓、肩部较窄、胸围较大且平坦、腰臀围较大、臀部较扁平且腹部凸出。该研究结果可为中孟在校青年男子版型制作提供体型依据。     

Microbiological spoilage of vacuum and modified atmosphere packaged Vietnamese Pangasius hypophthalmus fillets

This study investigated the identity, growth and metabolite production of micro-organisms causing spoilage of Pangasius hypophthalmus fillets packaged in air, vacuum and modified atmospheres (MAP) (MAP 1: 50%CO(2)-50%N(2) and MAP 2: 50%CO(2)-50%O(2)) during storage at 4 °C. Based on the time it took for psychrotrophic total colony counts to exceed 7 log cfu g(-1), the shelf life of the fillets packaged in air, vacuum, MAP 1 and MAP 2 was estimated to be 7, 10, 12 and 14 days respectively. The longest lag phases were observed in the samples packaged in MAP 2 (50%CO(2)-50%O(2)). In the fillets packaged in air and under vacuum, the dominant flora identified by partial 16S rDNA sequencing at the end of the shelf life generally consisted of Gram-negative bacteria mostly belonging to the genera Serratia and Pseudomonas. In contrast, lactic acid bacteria (Carnobacterium maltaromaticum and Carnobacterium divergens) and Brochothrix thermosphacta were identified as the dominant spoilage flora in the samples packaged under the two MAPs investigated. By means of solid-phase microextraction gas chromatography mass spectrometry (SPME GC-MS) analysis, volatile organic compounds in the headspace of the samples at the end of the shelf life were identified for each packaging condition. Based on these results, a selective ion flow tube mass spectrometry (SIFT-MS) method was developed to quantify the production of volatile metabolites during storage of the fillets. The results of these analyses indicated that several compounds contributed to the bacterial spoilage of Pangasius fillets e.g., ethanol, 2,3-butanediol, diacetyl, acetoin, ethyl acetate, acetic acid and sulfur compounds. It also emerged that the production of these compounds was dependent on the packaging condition applied.     

Antioxidant activity of the extracts from Dillenia indica fruits

There has been growing interest in the beneficial health effects of consuming fruits and vegetables. Mainly, the presence of phenolic antioxidants is believed to have the protective mechanisms. In the present study the fruit of Dillenia indica was extracted with ethyl acetate, methanol and water. The total phenolic content of the extracts was determined by Folin–Ciocalteu method and antioxidant activity of the extracts was assayed through some in vitro models such as antioxidant capacity by phosphomolybdenum method, β-carotene-linoleate model system, and radical scavenging activity using ,-diphenyl-β-picrylhydrazyl (DPPH) method. The total phenolic contents of the fruit extracts as tannic acid equivalents were found to be highest in methanol extract (34.1%) followed by ethyl acetate extract (9.3%) and water extract (1.4%). Antioxidant capacity of the extracts as equivalent to ascorbic acid (μmole/g of the extract) was in the order of methanol extract > ethyl acetate extract > water extract. In comparison with butylated hydroxyanisole (BHA), at 100 ppm of concentration, the antioxidant and free radical scavenging activities of the extracts assayed through β-carotene-linoleate model system, and DPPH method were also found to be highest with methanol extract followed by ethyl acetate and water extracts. The results indicated that the extent of antioxidant activity of the extract is in accordance with the amount of phenolics present in that extract and the fruit of D. indica is rich in phenolics may provide a good source of antioxidant.     

Laser and GTAW torch processing of Fe–Cr–B coatings on steel

A comparison has been made of the relationship between microstructure and microhardness developed by surface melting Nanosteel SHS 7170 Fe–Cr–B alloy powder onto a plain carbon steel surface. This powder was initially developed as a high velocity oxyfuel sprayed coating, giving a strength 10 times that of mild steel, and is particularly suitable for surface protection against wear and corrosion. In the present study, the alloy powder was injected into the laser melted surface, while a preplaced powder was melted using the gas tungsten arc welding (GTAW) technique. The laser track consisted of fine dendrites and needle-like microstructures, which produced a maximum hardness value of over 800 HV, while the GTAW track produced a mixture of equiaxed and columnar grain microstructures with a maximum hardness value of 670 HV. The lower hardness values are considered to be associated with dilution and grain size.