整体柱固相萃取结合GC-MS鉴定中药苍术水煎液化学成分

目的:制备并采用整体柱固相萃取柱鉴定苍术水煎液中的化学成分。方法:以甲基丙烯酸缩水甘油酯为单体,甲基丙烯酸乙二醇酯为交联剂,环己醇和十二醇为致孔剂,偶氮二异丁腈为氧化还原引发剂,制备整体柱。采用所制备整体柱对苍术水煎液进行固相萃取,结合GC-MS分析确定苍术水煎液的化学成分。结果:所建立的方法精密度1.08%,回收率为93.23%~104.52%,相对标准偏差为2.91%(n=6),结合GC-MS从苍术水煎液鉴定确定茅术醇、β-桉叶醇、苍术酮、红没药醇等化学成分。结论:采用所制备的整体柱固相萃取结合GC-MS分析可快速鉴定苍术中的化学成分。

阀外冷却技术在西北地区的应用与探讨

阀冷却系统的正常工作,是换流阀可靠运行的重要保证。介绍了目前在运换流站阀外冷却系统的各技术路线和西北地区银川东换流站、天山换流站的阀外冷却技术,针对天山站在调试期间发现问题,给出将在西北高温、严寒、风沙大等特殊气候建设的直流工程以合理化建议,为西北地区新开展工程的相关设备设计、制造和运行维护提供借鉴。

Study on the Spectrophotometric Determination of Rare Earths with a New Chromogenic Reagent Dibromo-p-methyl-chlorosulfonazo(DBMCSA)

A new method for the determination of cerium subgroup rare earths was studied and reported ill this paper. It was found that cerium subgroup rare earth elements react with DBMCSA in 0.6 mol/L hydrochloric acid medium to form stable blue complexes. The absorbances of equal amounts of cerium subgroup rare earths are close to each other at their maximum adsorptive wavelength (641 nm). Beer's law is obeyed for 0-20 mu g of I ars earths in 25 mi of solution. The method has been applied to the determination of the total amount of cerium subgroup rare earths in steel and cast iron samples with satisfactory results.

Visual Sentiment Analysis with Local Object Regions Attention

Human action recognition has gained popularity because of its worldwide applications such as video surveillance, video retrieval and human– computer interaction. This paper provides a comprehensive overview of notable advances made by deep neural networks in this field. Firstly, the basic conception of action recognition and its common applications were introduced. Secondly, action recognition was categorized as action classification and action detection according to its respective research goals. And various deep learning frameworks for recognition tasks were discussed in detail and the most challenging datasets and taxonomies were briefly reviewed. Finally, the limitations of the state-of-the-art and promising directions of the research were briefly outlined.

Physiological,transcriptome and gene functional analysis provide novel sights into cadmium accumulation and tolerance mechanisms in kenaf

Kenaf is considered to have great potential for remediation of heavy metals in ecosystems.However,studies on molecular mechanisms of root Cd accumulation and tolerance are still inadequate.In this study,two differently tolerant kenaf cultivars were selected as materials and the physiological and transcriptomic effects were evaluated under Cd stress.This study showed that 200μmol/L CdCl_(2) treatment triggered the reactive oxygen species(ROS)explosion and membrane lipid peroxidation.Compared with the Cd-sensitive cultivar‘Z',the Cd-tolerant cultivar‘F'was able to resist oxidative stress in cells by producing higher antioxidant enzyme activities and increasing the contents of ascorbic acid(AsA)and glutathione(GSH).The root cell wall of‘F'exhibited higher polysaccharide contents under Cd treatment,providing more Cd-binding sites.There were 3,439 differentially expressed genes(DEGs)that were co-regulated by Cd treatment in two cultivars.Phenylpropanoid biosynthesis and plant hormone signal transduction pathways were significantly enriched by functional annotation analysis.DEGs associated with pectin,cellulose,and hemi-cellulose metabolism were involved in Cd chelation of root cell wall;V-ATPases,ABCC3 and Narmp3 could participated in vacuolar compartmentalization of Cd;PDR1 was responsible for Cd effux;the organic acid transporters contributed to the absorption of Cd in soil.These genes might have played key roles in kenaf Cd tolerance and Cd accumulation.Moreover,HcZIP2 was identified to be involved in Cd uptake and transport in kenaf.Our findings provide a deeper understanding of the molecular pathways underlying Cd accumulation and detoxification mechanisms in kenaf.

Spontaneous mutations and mutational responses to penicillin treatment in the bacterial pathogen Streptococcus pneumoniae D39

Bacteria with functional DNA repair systems are expected to have low mutation rates due to strong natural selection for genomic stability.However,our study of the wild-type Streptococcus pneumoniae D39,a pathogen responsible for many common diseases,revealed a high spontaneous mutation rate of 0.02 per genome per cell division in mutation-accumulation(MA)lines.This rate is orders of magnitude higher than that of other non-mutator bacteria and is characterized by a high mutation bias in the A/T direction.The high mutation rate may have resulted from a reduction in the overall efficiency of selection,conferred by the tiny effective population size in nature.In line with this,S.pneumoniae D39 also exhibited the lowest DNA mismatch-repair(MMR)efficiency among bacteria.Treatment with the antibiotic penicillin did not elevate the mutation rate,as penicillin did not induce DNA damage and S.pneumoniae lacks a stress response pathway.Our findings suggested that the MA results are applicable to within-host scenarios and provide insights into pathogen evolution.

Contribution of the SOS response and the DNA repair systems to norfloxacin induced mutations in E.coli

Antibiotic-resistant bacteria severely threaten human health.Besides spontaneous mutations generated by endogenous factors,the resistance might also originate from mutations induced by certain antibiotics,such as the fluoroquinolones.Such antibiotics increase the genome-wide mutation rate by introducing replication errors from the SOS response pathway or decreasing the efficiency of the DNA repair systems.However,the relative contributions of these molecular mechanisms remain unclear,hindering understanding of the generation of resistant pathogens.Here,using newly-accumulated mutations of wild-type and SOS-uninducible Escherichia coli strains,as well as those of the strains deficient for the mismatch repair(MMR)and the oxidative damage repair pathways,we find that the SOS response is the major mutagenesis contributor in mutation elevation,responsible for~30–50%of the total base-pair substitution(BPS)mutation-rate elevation upon treatment with sublethal levels of norfloxacin(0~50 ng/mL).We further estimate the significance of the effects on other mutational features of these mechanisms(i.e.,transversions,structural variations,and mutation spectrum)in E.coli using linear models.The SOS response plays a positive role in all three mutational features(mutation rates of BPSs,transversions,structural variations)and affects the mutational spectrum.The repair systems significantly reduce the BPS mutation rate and the transversion rate,regardless of whether antibiotics are present,while significantly increasing the structural variation rate in E.coli.Our results quantitatively disentangle the contributions of the SOS response and DNA repair systems in antibiotic-induced mutagenesis.

An integrative protocol for one‑step PCR amplicon library construction and accurate demultiplexing of pooled sequencing data

High-throughput sequencing of amplicons has been widely used to precisely and efficiently identify species compositions and analyze community structures,greatly promoting biological studies involving large amounts of complex samples,especially those involving environmental and pathogen-monitoring ones.Commercial library preparation kits for amplicon sequencing,which generally require multiple steps,including adapter ligation and indexing,are expensive and time-consuming,especially for applications at a large scale.To overcome these limitations,a“one-step PCR approach”has been previously proposed for constructions of amplicon libraries using long fusion primers.However,efficient amplifications of target genes and accurate demultiplexing of pooled sequencing data remain to be addressed.To tackle these,we present an integrative protocol for one-step PCR amplicon library construction(OSPALC).High-quality reads have been generated by this approach to reliably identify species compositions of mock bacterial communities and environmental samples.With this protocol,the amplicon library is constructed through one regular PCR with long primers,and the total cost per DNA/cDNA sample decreases to just 7%of the typical cost via the multi-step PCR approach.Empirically tested primers and optimized PCR conditions to construct OSPALC libraries for 16S rDNA V4 regions are demonstrated as a case study.Tools to design primers targeting at any genomic regions are also presented.In principle,OSPALC can be readily applied to construct amplicon libraries of any target genes using DNA or RNA samples,and will facilitate research in numerous fields.

原发性肝癌合并肝动脉-门静脉分流的介入治疗进展

肝癌合并动脉-门静脉分流在临床上并不鲜见,严重制约并影响介入治疗的实施与效果。随着介入器材、血管超选技术、栓塞材料的发展以及近些年针对肝癌免疫及靶向药物的开发,肝癌合并动脉门静脉分流患者的预后有了明显的改善。文章旨在总结肝细胞癌合并动脉-门静脉分流的介入治疗进展,并讨论目前介入治疗中存在的挑战。

The insect-killing bacterium Photorhabdus luminescens has the lowest mutation rate among bacteria

Mutation is a primary source of genetic variation that is used to power evolution.Many studies,however,have shown that most mutations are deleterious and,as a result,extremely low mutation rates might be benefcial for survival.Using a mutation accumulation experiment,an unbiased method for mutation study,we found an extremely low base-substitution mutation rate of 5.94×10^(-11) per nucleotide site per cell division(95%Poisson confdence intervals:4.65×10^(-11),7.48×10^(-11))and indel mutation rate of 8.25×10^(-12) per site per cell division(95%confdence intervals:3.96×10^(-12),1.52×10^(-11))in the bacterium Photorhabdus luminescens ATCC29999.The mutations are strongly A/T-biased with a mutation bias of 10.28 in the A/T direction.It has been hypothesized that the ability for selection to lower mutation rates is inversely proportional to the efective population size(drift-barrier hypothesis)and we found that the efective population size of this bacterium is signifcantly greater than most other bacteria.This fnding further decreases the lower-bounds of bacterial mutation rates and provides evidence that extreme levels of replication fdelity can evolve within organisms that maintain large efective population sizes.

Cost-reduction strategies in massive genomics experiments

Many modern biology studies require deep, whole-genome sequencing of hundreds to thousands of samples. Although persamplecosts have dramatically decreased, the total budget for such massive genome sequencing constitutes a significantbarrier for poorly funded labs. The costly lab tools required for genomics experiments further hinder such studies. Here, weshare two strategies for extensively reducing the costs of massive genomics experiments, including miniaturization of theNEBNext Ultra II FS DNA Library Prep Kit for Illumina (reducing the per-sample total costs to ~ 1/6 of that charged byservice providers) and in-lab 3D model-designing of genomics tools. These strategies not only dramatically release fundingpressure for labs, but also provide students with additional training in hands-on genomics and 3D-model-designing skills,demonstrating the high potential for their application in genomics experiments and science education.

Pollutant reduction effectiveness of low-impact development drainage system in a campus

Building a rainwater system based on the idea of low-impact development （LID） is an important aspect of the current ＂sponge city＂ construction in China. The ＂sponge city＂ concept emphasizes that the runoff can permeate the soil or be stored temporarily, and rainwater could be used again when it is needed. Beijing is one of the earliest cities to study rainwater harvesting and LID techniques in China.Through long-terua monitoring of rainfall, runoff flow, and water quality of a campus demonstration project in Beijing, the runoff quantity and pollutant concentration variations have been analyzed. Furthermore, the runoffreduction effects of single LID measure, such as green roof, filtration chamber, and permeable pavement, have been investigated. Additionally, the overall reduction effectiveness of the LID system on the average annual rainfall runoff and pollution load has been discussed.