Biological variables as soil quality indicators: Effect of sampling time and ability to classify soils by their suitability

Soil biological variables are considered good soil quality indicators due to their high sensitivity and ability to reflect soil management effects. However, they frequently show high temporal variability. Our objectives were: (a) to analyze temporal stability and seasonal effect on biological variables, (b) to choose between autumn and spring to sample for soil biological variables, and (c) to determine biological variables able to discriminate among selected soil subgroups. Areas with minimal human disturbance were sampled in three soil orders (Mollisol, Vertisol and Alfisol) during two and a half years, each autumn and spring. Microbial biomass C and N (MBC, MBN), basal respiration (Resp), metabolic quotient (qCO₂), potential of N mineralization (PNM-AI), soil organic C (TOC) and total soil N (TON) were measured in three composite soil samples collected from homogeneous areas at 0–15 cm depth. For the studied soils, selected soil biological variables presented different levels depending on the time of sampling, spring or autumn. Hence, the importance of pointing out the time of sampling to report results of these variables in this kind of studies is remarked. In general, biological variables presented higher stability when we sampled soils in autumn compared to spring. Because of this, we used autumn soil samples to determine the best soil biological variables to discriminate among selected subgroups of soils. The separation of soil subgroups by means of discriminant analysis using just TOC and TON was scrutinized, considering that these soil variables are routinely measured in soil test laboratories. Nonetheless they were not able to discriminate properly among soil subgroups because they showed high error rates classifying the samples in the correct subgroups. In contrast, the variables PMN-AI, MBC, and MBN adequately discriminated the five soil subgroups. From the biological variables, PMN-AI and MBC were the best ones to characterize (discriminate) among the five soil subgroups. Particularly, PMN-AI was able to separate soils by their suitability for agricultural purposes.     

Influence of vegetable oils fatty-acid composition on biodiesel optimization

Biodiesel is an alternative fuel for diesel engines produced through transesterification of oleaginous feedstocks. To analyze the influence of the fatty-acid composition on biodiesel optimization, transesterification of several vegetable oils has been studied. Reactions were carried out in flasks filled with vegetable oils, heated to the reaction temperature and stirred at 1100 rpm. The reactions started when the methanol and potassium hydroxide solutions were added to the flasks. Concentration of catalyst, amount of methanol, reaction temperature and time were optimized using a factorial design and a surface response design. Also, a kinetics study was carried out to optimize the reaction time. Results showed that reaction parameters optimal values depend on the oil chemical and physical properties. It can be concluded from this field trial that the effect of both catalyst concentration and reaction time over the transesterification yield is greatly influenced by the saturation degree and fatty-acid chain length.     

Performance of a mobile mechanical screen to improve the commercial quality of wood chips for energy

The study analyzed the performance of a mobile screening device for upgrading coarse wood chips to residential user standards, by removing oversize particles and fines. The machine was designed for transportation to forest landings, logistic terminals and plant chip yards. Average productivity was 1.9 oven-dry tons (odt) h⁻¹, corresponding to a screening cost of 28.5 € odt⁻¹. This figure was lower than the price increase obtained by upgrading industrial chips to residential user standards. Hence, screening offered a profit of 4.7 € odt⁻¹, or 16% of the original screening cost. The screening process was capable of upgrading chips from industrial to residential specifications, by reducing the incidence of oversize particles below the 1% critical threshold. Screening also allowed a substantial reduction in the content of fines. A similar effect was not verified for crushed wood, which failed to meet the specifications for residential fuel.     

QTL for mohair traits in South African Angora goats

The aim of this study was to identify QTL associated with mohair production and quality traits in South African Angora goats. Limited research has been performed on QTL influencing the economically important mohair traits of Angora goats. Twelve half-sib Angora goat families with an average of 58 offspring per sire were genotyped for 88 microsatellites covering 22 autosomes. Phenotypic data was collected at second and third shearing for males and females respectively. A linkage analysis was performed under the half-sib model using the least squared regression approach of GridQTL. Three putative QTL were detected for fleece weight on CHI 2, 5 and 24, which corresponds with the locations of keratin and keratin-associated proteins. This study detected two putative QTL associated with mohair fibre diameter (on CHI 4 and 24, respectively), which is the most important price-determining trait. Four QTL were detected on CHI 8, 13, 18 and 20 which influence both comfort factor and spinning fineness. The variance explained by the QTL ranged between 6.9% for fibre diameter and 33.6% for standard deviation along the length of the staple. These results reveal segregation of QTL influencing mohair production and quality, and contribute to the understanding of the genetic variation of mohair traits.     

捕获-再捕获抽样中的多元组合估计量

首先介绍了捕获-再捕获抽样的思想方法以及Peterson估计量与性质,然后指出了Peterson估计量存在的问题,在此基础上给出了多元组合估计量并研究了它的性质.     

牡竹属三竹种的秆形质量与材性比较

通过牡竹属(Dendrocalamus) 3个竹笋品质佳的竹种（勃氏甜龙竹(D.brandisii)、马来麻竹(D. asper)、花吊丝竹(D. minor var. amoenus)）竹材形态质量及材性比较的研究,结果表明：种间立竹枝下高、相对全高差异显著或极显著,勃氏甜龙竹相对枝下高最小,立竹胸径、全高、枝下高、尖削度值、壁厚率均为最大;竹秆含水率随立竹年龄增大而下降,3年立竹竹秆含水率花吊丝竹>勃氏甜龙竹>马来麻竹,种间差异极显著;相对材积勃氏甜龙竹（1771.35cm 3 cm-1）>马来麻竹（1166.66 cm3 cm-1）>花吊丝竹（659.78 cm3 cm-1）,种间差异极显著;竹材密度随立竹年龄增大而提高,3a立竹竹材密度花吊丝竹（0.914 g.cm-3）>勃氏甜龙竹(0.812 g.cm-3)>马来麻竹（0.749 g.cm-3）,种间差异显著。综合分析勃氏甜龙竹、马来麻竹可作为优良的笋材兼用竹种,花吊丝竹宜作为笋用、观赏竹种推广应用。     

Microbiological quality of grey-mullet roe

The Greek grey-mullet roe is produced from the fully developed gonads of the female mullet (Mugil cephalus) couth in lagoons during their reproductive migration. The traditional processing method of the roe includes, air drying, salting, shape formation and covering with multiple layers of natural beeswax for preservation and distribution. Fish Roe brands have been a staple in local diet and is increasingly becoming popular in the international market. As a ready-to-eat food it’s microbial quality should be of concern for the protection of consumers health. In this study, 48 samples of fish roe, just before waxing, were collected from various local processors for microbiological examination by using selective media and incubated under aerobic and anaerobic conditions. The identification of the bacteria was carried out according to the Bergey’s manual. Microscopic examination of Gram stained cells, catalase, oxidase and biochemical tests were performed when necessary to further identify.V. parahaemolyticus, Vibrio spp., Salmonella spp., and Aeromonas hydrophila were detected in one sample (2%). Shigella spp., and Flavobacterium spp. in two samples (4%), Clotriduim perfringens (vegetative forms), E. coli, and spores of Bacillus spp., were detected in three samples (6%), Staphylococcus aureus in four samples (8%). Various Micrococcus spp., and spores of C. perfringens in 16% and 35% of the samples respectively. From the Listeria genus, only the species Listeria innocua, Listeria welshimeri, Listeria seeligeri Listeria ivanovii and Listeria grayi were recovered from 2 to 10% of the samples.Microbiological analyses revealed the presence of a small number of pathogens in grey-mullet roe samples which are in accordance with the findings of similar studies. Traditional processing of the fish roe, seems inadequate to ensure the food safety and even waxing isn’t expected to fully protect them against facultative anaerobes with salt tolerance. Therefore, additional measures should be taken during processing and marketing of fish roe to minimize potential health risks for the consumers.     

Scale specific determinants of tree diversity in an old growth temperate forest in China

The major processes generating pattern in plant community composition depend upon the spatial scale and resolution of observation, therefore understanding the role played by spatial scale on species patterns is of major concern. In this study, we investigate how well environmental (topography and soil variables) and spatial variables explain variation in species composition in a 25-ha temperate forest in northeastern China. We used new variation partitioning approaches to discover the spatial scale (using multi-scale spatial PCNM variables) at which environmental heterogeneity and other spatially structured processes influence tree community composition. We also test the effect of changing grain of the study (i.e. quadrat size) on the variation partitioning results. Our results indicate that (1) species composition in the Changbai mixed broadleaf-conifer forest was controlled mainly by spatially structured soil variation at broad scales, while at finer scales most of the explained variation was of a spatial nature, pointing to the importance of biotic processes. (2) These results held at all sampling grains. However, reducing quadrat size progressively reduced both spatially and environmentally explained variance. This probably partly reflects increasing stochasticity in species abundances, and the smaller proportion of quadrats occupied by each species, when quadrat size is reduced. The results suggest that environmental heterogeneity (i.e. niche processes) and other biotic processes such as dispersal work together, but at different spatial scales, to build up diversity patterns.     

肾衰康浓缩丸质量标准研究

目的：建立肾衰康浓缩丸质量控制方法。方法：采用TLC鉴别肾衰康浓缩丸中大黄、丹参;采用HPLC-ELSD对制剂中黄芪甲苷进行含量测定,流动相为乙腈-水（30：70）,流速：1 mL/min,柱温：28℃,漂移管温度：42℃,氮气：355kPa。结果：大黄、丹参的TLC鉴别斑点清晰、专属性强;黄芪甲苷在1.0μg-10.0μg之间呈良好的线性关系（r=0.9997,n=5）,平均回收率为99.81%,RSD为1.73%（n=6）。结论：所建立的方法简便准确、专属性强、重现性好,可作为控制肾衰康浓缩丸质量的方法。