南阳酵母2.577原生质体制备和再生条件的研究

南阳酵母2.577是生产燃料乙醇的一种重要的酵母菌.为了培养出一种性能更好的酵母菌,以南阳酵母2.577为出发菌,研究菌龄、酶解温度、酶解时间、酶浓度4个因素对其原生质体形成率和再生率的影响.结果表明:当菌龄为12 h、酶浓度为2.O%、酶解时间为2 h、酶解温度为28℃时,南阳酵母2.577原生质体的形成率和再生率能分别达到最高值.     

Tertiary-treated municipal wastewater is a significant point source of antibiotic resistance genes into Duluth-Superior Harbor

In this study, the impact of tertiary-treated municipal wastewater on the quantity of several antibiotic resistance determinants in Duluth-Superior Harbor was investigated by collecting surface water and sediment samples from 13 locations in Duluth-Superior Harbor, the St. Louis River, and Lake Superior. Quantitative PCR (qPCR) was used to target three different genes encoding resistance to tetracycline (tet(A), tet(X), and tet(W)), the gene encoding the integrase of class 1 integrons (intI1), and total bacterial abundance (16S rRNA genes) as well as total and human fecal contamination levels (16S rRNA genes specific to the genus Bacteroides ). The quantities of tet(A), tet(X), tet(W), intI1, total Bacteroides , and human-specific Bacteroides were typically 20-fold higher in the tertiary-treated wastewater than in nearby surface water samples. In contrast, the quantities of these genes in the St. Louis River and Lake Superior were typically below detection. Analysis of sequences of tet(W) gene fragments from four different samples collected throughout the study site supported the conclusion that tertiary-treated municipal wastewater is a point source of resistance genes into Duluth-Superior Harbor. This study demonstrates that the discharge of exceptionally treated municipal wastewater can have a statistically significant effect on the quantities of antibiotic resistance genes in otherwise pristine surface waters.     

Short communication: effects of replacing part of corn silage and alfalfa hay with Leymus chinensis hay on milk production and composition

The objective of this research was to investigate the effects of replacing part of corn silage (CS) and alfalfa hay (AH) with Leymus chinensis hay on milk production and composition. Twenty multiparous Holstein dairy cows were used in a randomized block design for a 14-week period and 2 treatments. Treatments were (dry matter basis): (1) Non-Leymus chinensis hay diet (NLC; 35% CS, 15% AH) and (2) added Leymus chinensis hay diet (ALC; 30% CS, 10% AH, 10% Leymus chinensis hay). Adding Leymus chinensis hay increased neutral detergent fiber content and in vitro digestibility of the diet. Cows receiving the ALC diet had higher dry matter intake, milk yield, milk protein yield, lactose yield, solids-not-fat yield, and milk fat content compared with those fed the NLC diet. Somatic cell counts of cows decreased in the ALC compared with the NLC treatment. Cis-11 18:1 and 18:2 contents in milk increased, whereas trans-9 and cis-9 18:1 fatty acid contents decreased. Trans-9, cis-11 conjugated linoleic acid content was not influenced by adding Leymus chinensis hay to the diet. Leymus chinensis hay can be used to replace part of CS and AH in diets of dairy cows to get higher milk yield and good milk quality.     

Complex microbiota of a Chinese "Fen" liquor fermentation starter (Fen-Daqu), revealed by culture-dependent and culture-independent methods

Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen-Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture-independent approaches (PCR-DGGE). A total of 190 microbial strains, comprising 109 bacteria and 81 yeasts and moulds, were isolated and identified on the basis of the sequences of their 16S rDNA (bacteria) and 26S rDNA and ITS regions (fungi). DGGE of DNA extracted from Daqu was used to complement the culture-dependent method in order to include non-culturable microbes. Both approaches revealed that Bacillus licheniformis was an abundant bacterial species, and Saccharomycopsis fibuligera, Wickerhamomyces anomalus, and Pichia kudriavzevii were the most common yeasts encountered in Fen-Daqu. Six genera of moulds (Absidia, Aspergillus, Mucor, Rhizopus, Rhizomucor and Penicillium) were found. The potential function of these microorganisms in starters for alcoholic fermentation is discussed. In general the culture-based findings overlapped with those obtained by DGGE by a large extent. However, Weissella cibaria, Weissella confusa, Staphylococcus saprophyticus, Enterobacter aerogenes, Lactobacillus sanfranciscensis, Lactobacillus lactis, and Bacillus megaterium were only revealed by DGGE.     

天然虾青素对辐射损伤小鼠辅助保护作用

目的:探讨天然虾青素对小鼠辐射损伤的保护作用。方法:将144只小鼠随机分为3个实验组,剂量分别为100、200、600mg/kg·bw,另设一个辐射对照组,每天灌胃1次,连续20d后,各组均以60Co射线进行一次全身照射,并继续给样品。辐照前、辐照后第3d和14d进行外周血细胞计数;辐照后第3d进行骨髓有核细胞计数和骨髓细胞微核实验;辐照后第14d测定血清溶血素。结果:与辐照模型对照组比较,600mg/kg·bw剂量组能增加外周血白细胞计数,增加小鼠血清溶血素含量,200mg/kg·bw和600mg/kg·bw剂量组能增加小鼠骨髓有核细胞数,降低骨髓细胞微核率。结论:天然虾青素对辐射损伤具有一定的保护作用。     

Effect of dispersion on adsorption of atrazine by aqueous suspensions of fullerenes

With the widespread application of fullerenes, it is critical to assess their environmental behaviors and their impacts on the transport and bioavailability of organic contaminants. The effects of fullerene particle size, chemistry of the solution, and natural organic matter on the adsorption of atrazine by aqueous dispersions of fullerenes (C(60)) were investigated in this work. The results showed that the Polanyi-Manes model could fit the adsorption isotherms well. Smaller sizes of fullerene particles led to increased available sites and, consequently, enhanced the adsorption of atrazine on C(60). However, intensely dispersed C(60) systems might not possess suitably high adsorptive capacities due to surface chemistry change. Adsorption of atrazine by aqueous dispersions of C(60) increased with a decrease in the pH of the solution. Introduction of humic acid significantly reduced the size of the C(60) particles, and resulted in the increase of the adsorption amount. Fullerene materials, once released into the aquatic environment, are inclined to form aqueous suspensions with different degrees of dispersion, which would greatly affect the transport and fate of organic contaminants.     

Metal-Organic Framework Nanocarriers for Drug Delivery in Biomedical Applications

Investigation of metal–organic frameworks(MOFs)for biomedical applications has attracted much attention in recent years.MOFs are regarded as a promising class of nanocarriers for drug delivery owing to well-defined structure,ultrahigh surface area and porosity,tunable pore size,and easy chemical functionalization.In this review,the unique properties of MOFs and their advantages as nanocarriers for drug delivery in biomedical applications were discussed in the first section.Then,state-ofthe-art strategies to functionalize MOFs with therapeutic agents were summarized,including surface adsorption,pore encapsulation,covalent binding,and functional molecules as building blocks.In the third section,the most recent biological applications of MOFs for intracellular delivery of drugs,proteins,and nucleic acids,especially aptamers,were presented.Finally,challenges and prospects were comprehensively discussed to provide context for future development of MOFs as efficient drug delivery systems.     

Tiered clustering-based management architecture in mega-satellite networks

Hybrid orbital networking and the proliferation of satellites raise explosive management complexity in mega-satellite networks(MSNs) and prompt the management architecture to the hierarchy. In this regard, we propose a tiered clustering-based management architecture(TCMA) to realize the high-efficient and low-cost management performance. Specifically, based on the constrained satellite coverage, we derive an expression of the mapping relationship between the required control overhead of the cont...     

Corrosion mechanism of ceramic glaze from the Yangtze Estuary Ⅱ

Ancient lead-glazed ceramics frequently corrode physically, chemically, and biologically when buried in soil, submerged in water, or exposed to air. In comparison to the other two environments, relatively little research has been conducted on how leadglazed ceramics deteriorate in the water environment. Four lead-glazed ceramic samples from the Yangtze Estuary Ⅱ were examined for their micromorphology and structural composition using scanning electron microscopy-energy spectrum analysis,micro-ar...     

Low-loss wide-bandwidth planar transmission line with a laminated conductor

In this paper, the laminated conductor technology is first introduced to planar-integrated transmission lines. The laminated conductor is composed of multilayers of metal and insulator, which has a lower conductor loss than a solid conductor. Based on the silicon-based micro electromechanical system technology,a laminated coplanar waveguide(CPW) with wide bandwidth and low loss is proposed, which uses a laminated conductor for signal lines and grounds. A laminated CPW and its transition are desi...