Effect of infiltrating time on interfacial reaction and properties of tungsten particles reinforced Zr-based bulk metallic glass composites

The tungsten particles reinforced Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit 1 alloy) bulk metallic glass composites (BMGCs) were prepared by the melt infiltrating casting method with the infiltrating time of 1, 5 and 10 min, respectively. The changes of interfacial reaction and compression properties of the bulk metallic glass composites with different infiltrating times were studied. Results show that with the increase of infiltrating time, tiny nanocrystals are generated at the interfacial boundary of tungsten particles and the amorphous matrix, and the size of tiny crystals increases with the infiltrating time. When the infiltrating time is 10 min, polygonal crystals with a larger size are also generated within the amorphous matrix. The compressive strength of the composites also increases with the infiltrating time. When the infiltrating time is 10 min, the compressive strength of the composite reaches 2,030 MPa and the compression strain is 44%. The fracture morphology of the composite materials is in a vein-like pattern and the melting phenomenon is found on the fracture surface. In addition, the density of the shear bands during the compressive tests of the composite materials increases with the infiltrating time.

Fudan multi-purpose active target time projection chamber(fMeta-TPC)for photonuclear reaction experiments

Active target time projection chambers are state-of-the-art tools in the field of low-energy nuclear physics and are particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays.The Fudan multi-purpose active target time projection chamber(fMeta-TPC)with 2048 channels was developed to studyα-clustering nuclei.This study focused on the photonuclear reaction with a laser Compton scattering gamma source,particularly for the decay of the highly excitedαcluster state.The design of fMeta-TPC is described in this paper.A comprehensive evaluation of its offline performance was conducted using an ultraviolet laser and ^(241)Amαsource.The results showed that the intrinsic angular resolution of the detector was within 0.30°,and the detector had an energy resolution of 6.85%for 3.0 MeVαparticles.The gain uniformity of the detector was approximately 10%(RMS/Mean),as tested by the ^(55)Fe X-ray source.

Singularly perturbed reaction diffusion equations with time delay

A class of initial boundary value problems of differential-difference equations for reaction diffusion with a small time delay is considered. Under suitable conditions and by using the stretched variable method, a formal asymptotic solution is constructed. Then, by use of the theory of differential inequalities, the uniform validity of the solution is proved.

A direct real-time polymerase chain reaction assay for rapid high-throughput detection of highly pathogenic North American porcine reproductive and respiratory syndrome virus in China without RNA purification

Background： Porcine reproductive and respiratory syndrome virus （PRRSV）, and particularly its highly pathogenic genotype （HP-PRRSV）, have caused massive economic losses to the global swine industry. Results： To rapidly identify HP-PRRSV, we developed a direct reaL-time reverse transcription polymerase chain reaction method （dRT-PCR） that could detect the virus from serum specimen without the need of RNA purification Our dRT-PCR assay can be completed in 1.5 h from when a sample is received to obtaining a result. Additionally, the sensitivity of dRT-PCR matched that of conventional reverse transcription PCR （cRT-PCR） that used purified RNA The lowest detection limit of HP-PRRSV was 6.3 TCIDs0 using dRT-PCR. We applied dRT-PCR assay to 144 field samples and the results showed strong consistency with those obtained by cRT-PCR. Moreover, the dRT-PCR method was able to tolerate 5-20% （v/v） serum. Conclusions： Our dRT-PCR assay allows for easier, faster, more cost-effective and higher throughput detection of HP-PRRSV compared with cRT-PCR methods. To the best of our knowledge, this is the first report to describe a real-time RT-PCR assay capable of detecting PRRSV in crude serum samples without the requirement for purifying RNA. We believe our approach has a great potential for application to other RNA viruses.

Luminescent properties dependence of water-soluble CdTe quantum dots on stabilizing agents and reaction time

The influence of stabilizing agents and reaction time on the luminescent properties of water-soluble CdTe quantum dots(QDs) was discussed.The thioglycolic acid(TGA)-CdTe ODs were characterized by TEM,XRD and FTIR.It is found that larger-size QDs can be synthesized more easily when L-cysteine(Cys) or golutathione(GSH) is chosen as stabilizing agent and TGA is proper to prepare highly luminescent QDs because of the effect between Cd2+ and sulfhydryl group.Furthermore,the absorption wavelength,full width at half maximum(FWHM),stokes shift,photoluminescence(PL) quantum yield and PL stability of TGA-CdTe are strongly dependent on reaction time,in which the absorption wavelength changes against reaction time with an exponential function.The TGA-CdTe QDs prepared at 2 h possess more excellent luminescent properties.

Locked nucleic acid real-time polymerase chain reaction method identifying two polymorphisms of hepatitis B virus genotype C2 infections,rt269L and rt269I

BACKGROUND The presence of two distinct hepatitis B virus(HBV)Pol RT polymorphisms,rt269L and rt269I,could contribute to the unique clinical or virological phenotype of HBV genotype C2.Therefore,a simple and sensitive method capable of identifying both types in chronic hepatitis B(CHB)patients infected with genotype C2 should be developed.AIM To develop a novel simple and sensitive locked nucleic acid(LNA)-real timepolymerase chain reaction(RT-PCR)method capable of identifying two rt269 types in CHB genotype C2 patients.METHODS We designed proper primer and probe sets for LNA-RT-PCR for the separation of rt269 types.Using synthesized DNAs of the wild type and variant forms,melting temperature analysis,detection sensitivity,and endpoint genotyping for LNA-RT-PCR were performed.The developed LNA-RT-PCR method was applied to a total of 94 CHB patients of genotype C2 for the identification of two rt269 polymorphisms,and these results were compared with those obtained by a direct sequencing protocol.RESULTS The LNA-RT-PCR method could identify two rt269L and rt269I polymorphisms of three genotypes,two rt269L types[‘L1’(WT)and‘L2’]and one rt269I type(‘I’)in single(63 samples,72.4%)or mixed forms(24 samples,27.6%)in 87(92.6%sensitivity)of 94 samples from Korean CHB patients.When the results were compared with those obtained by the direct sequencing protocol,the LNA-RT-PCR method showed the same results in all but one of 87 positive detected samples(98.9%specificity).CONCLUSION The newly developed LNA-RT-PCR method could identify two rt269 polymorphisms,rt269L and rt269I,in CHB patients with genotype C2 infections.This method could be effectively used for the understanding of disease progression in genotype C2 endemic areas.

Converting of MSW into Valuable Hydrocarbons by Pyrolysis： Effect of Paper/Plastic Ratio and Reaction Time

Municipal solid wastes from industrial plants were pyrolyzed in a fixed bed reactor to evaluate the influence of paper/plastic ratio and reaction time both on product quantity and quality. Raw materials have been pyrolyzed under nitrogen in a 3.0 dm^3 autoclave. Results show considerable differences in yields and quality of products obtained by pyrolysis of wastes with different paper content. Light and heavy oils were mixtures of organic compounds containing valuable hydrocarbons and oxygenated chemicals, while chars were rather composed of inorganic compounds from the raw materials. Longer reaction time of pyrolysis had produced higher non-condensable gas, water and light oil. Gases contained CO, CO2 and hydrocarbons, but the concentrations were very function of reaction time and paper/plastic ratio. Light and heavy oils showed similarities with middle distillates and heavy oils in refinery, the high paper content of the raw materials was unfavourable for longer storage of waste derived oils.

Investigation of solid-state reaction by terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy(THz-TDS)was utilized to investigate the solid-state reaction between L(+)-Tartaric acid and sodium hydrogen carbonate.Solid sodium hydrogen L(+)-tartrate monohydrate was synthesized efficiently by mechanical grinding,which is particularly sustainable and environmentally benign.Distinct THz absorptions were observed for pure reactants and the proposed product.The reaction process could be clearly visualized by THz spectral patterns of the reaction mixtures at different grinding time.The observed results were further confirmed by synchrotron radiation X-ray powder diffraction(SRXRPD)and Fourier transform infrared (FT-IR)spectroscopy.The study demonstrates that THz-TDS is an effective novel tool to monitor solid-state reactions in pharmaceutical industry.

金黄色葡萄球菌基因表达的DNA扣除法Real-time RT PCR相对定量分析

【目的】金黄色葡萄球菌作为一种分布广泛的致病微生物和研究革兰氏阳性菌遗传背景的模式菌株,利用real-time RT PCR对相关毒素及调控基因进行表达定量分析,在生物、医学、食品检测等领域具有较大研究价值。【方法】对制备好的反转录(RT,含有cDNA和DNA)和非反转录(RT—,仅含DNA)样品进行Real-time PCR检测,根据经典(1+E)—△△Ct相对定量算法并结合PCR效率公式建立一种基因表达相对定量分析的DNA扣除法,将得到的Ct值转换为各样品含量,从RT样品中扣除RT—样品的量,无需DNaseⅠ酶解处理就可以去除DNA的影响,RT—样品的检测结果还可同时作为稳定的DNA内参。【结果】采用以上方法分析金黄色葡萄球菌肠毒素A基因(sea)、16S rRNA和RNAⅢ的表达情况,在含有葡萄糖的NB培养基中sea的相对转录水平随着葡萄糖浓度的增大而升高,RNAⅢ的相对转录水平随葡萄糖浓度的变化而产生小幅度的波动,16S rRNA在菌体生长初期时的表达量较为稳定;与绝对定量法比较,结果差异较小(均小于15%),且差异不显著(p>0.05)。【结论】这种基于DNA扣除法的Real-time RT PCR相对定量方法可以有效的对金黄色葡萄球菌的基因表达进行分析。

Real-time RT-PCR检测西尼罗病毒一步法的建立

目的建立针对西尼罗病毒E基因的一步法Real-time RT-PCR检测方法,用于西尼罗病毒感染样本的快速准确检测和定量。方法针对西尼罗病毒的保守基因E设计引物和探针,建立一步法Real-time RT-PCR反应方法并分析敏感性和特异性。结果本研究建立的一步法Real-time RT-PCR方法可以特异性检测出西尼罗病毒,不与日本脑炎病毒及其他病毒产生交叉反应。该方法的最低检出浓度为3.6×102copies/μl,标准曲线的线性范围为3.6×102～3.6×107copies/μl。结论本研究建立的一步法real-time RT-PCR方法敏感性和特异性较高,且不易出现污染引起的假阳性结果,适合用于西尼罗病毒感染样本的检测。

Real-time TaqMan RT-PCR快速检测犬瘟热病毒方法的研究

按照犬瘟热(CDV)N基因序列,设计合成了特异性引物和探针,经各反应条件的优化,建立了Real-time荧光定量RT-PCR技术,对细胞培养物、肝脏、肺脏、脑、脾脏、淋巴结以及鼻腔拭子等组织病料中的CDV进行了特异性检测和敏感性试验。同时,利用建立的Real-time荧光定量RT-PCR方法与常规RT-PCR以及韩国BIOINDIST生产的BIT RAPID CDV检测试剂盒对57份临床样品进行了检测。结果:用20pmol/mL的引物浓度各1uL和20pmol/mL的探针浓度0．3uL,获得的荧光信号最强,曲线平滑。敏感性高,可检测到1．24×10—3ng/uL的病毒RNA;特异性强,与NDV、AIV、NiPV等RNA病毒不发生交叉反应。试验重复性的变异系数(CV)分别为2．3%、2．5%和4．2%;与常规RT-PCR和BIOINDIST生产的BIT RAPID CDV检测试剂盒相比较,该方法具有快速、特异、敏感、可定量,并可同时检测大量样品等优点。

赤羽病病毒Real-time RT-PCR检测方法的建立与初步应用

为了研究赤羽病病毒的检测方法，试验根据GenBank中已发表的赤羽病病毒（Akabanevirus，AKAV）的s基因序列建立了检测AKAV的Real-timeRT—PCR方法。结果表明：该方法对AKAV的检测有高度的特异性，与牛病毒性腹泻病毒（BVDV）、传染性牛鼻气管炎病毒（IBRV）等13种病毒均无交叉反应；Real—timeRT—PCR能够扩增稀释度为1×10^-5的病毒RNA（核酸含量约1．18ng／μL），比普通RT—PCR高出1000倍；用此方法检测130份奶牛血清样品与1份流产胎儿病料，均未检测到阳性样本；AKAV在血清模拟样品中可被有效检出。

检测粪便中GGⅡ型诺如病毒Real-time RT-PCR方法的建立

诺如病毒是世界急性胃肠炎的重要病原之一。为加强其控制，通过序列比对设计出针对GGⅡ型诺如病毒保守序列的特异性引物与探针，建立了TaqMan Real-time RT-PCR方法。结果显示，此方法对诺如病毒核酸检测高度特异，与轮状病毒、腺病毒、甲型肝炎病毒等无交叉反应，最低检出限可达10^2拷贝，线性范围为100～100拷贝，标准曲线的相关系数为-1．00。针对标准品质粒检测的批内实验变异系数为0．28％～1．63％（n=6）、批间实验为0．28％～1．05％（n=3），对同一样品分6次进行RNA提取和逆转录，其变异系数为3增8％。对212份临床腹泻标本分别用常规RT-PCR和本文建立的TaqMan Real-time PCR进行检测，发现后者检出率略高于前者。这些结果提示此研究建立的诺如病毒的TaqMan Real-time RT-PCR检测方法可用于临床腹泻粪便标本的检测。

鸡传染性支气管炎病毒Real-time RT-PCR检测方法的建立及应用

为定量检测鸡传染性支气管炎病毒(IBV)载量,建立IBV的Real-timeRT-PCR方法。用RT-PCR方法扩增出IBV的N基因片段,并克隆到pEASY-T3载体中,构建成含有N基因片段的重组质粒。应用该重组质粒进行SYBRGreenⅠReal-timePCR,建立了定量检测IBV核酸的标准曲线与直线回归方程,该方法显示:特异性强,检测下限至少达到5.58×102拷贝/μL,其重复性试验的变异系数小于3.2%;用建立的方法对实验接种IBVM41株的雏鸡组织中的病毒核酸进行了定量检测,检测结果显示:攻毒后肾脏中IBV含量高于支气管和肺脏,支气管和肺脏中病毒含量在攻毒后第3天高于攻毒后第7、10天,并证实临床表现与病毒载量之间存在密切关系。研究结果表明,建立的Real-timeRT-PCR检测方法特异性强、灵敏度高、可重复性好,可用于IBV的定量检测。

利用real-time RT-PCR研究大型蚤对铜绿微囊藻毒素合成基因转录水平影响

近年来关于浮游动物与微囊藻相互作用的研究逐渐被关注,其中有的研究认为浮游动物能够诱导产毒细胞毒素含量的变化.微囊藻毒素是由微囊藻毒素合成基因编码翻译的,目前关于浮游动物对微囊藻毒素合成基因相对表达的影响并无报道,本文首次通过实时定量逆转录PCR方法研究铜绿微囊藻PCC7806产毒相关基因mcyB和mcyD在大型蚤胁迫下相对表达变化.结果显示微囊藻mcyB、mcyD基因相对表达均有上调,表明铜绿微囊藻PCC7806通过上调产毒基因的转录水平达到对大型蚤的诱导防御,从而为浮游动物与微囊藻相互作用研究提供新的依据.

猴逆转录病毒RT-PCR和Real-time RT-PCR检测方法的建立

猴逆转录病毒(Simian type D retrovirus,SRV)是引起猴获得性免疫缺陷综合征(Simian acquired immunodeficiency syndrome,SAIDS)的病原之一,其严重危害猴的健康,并威胁与猴接触人员的健康,是无特定病原体(SPF)猴必须排除的病毒之一。为了应对口岸对进出境野生及实验用灵长类动物SRV感染情况的监测和流行病学调查的需要,建立了RT-PCR和real-time RT-PCR检测SRV的方法,并对方法的特异性、敏感性和稳定性进行了验证。

基因重组构建AFP mRNA的real time RT-PCR标准定量模板

目的 :构建AFPmRNA的realtimeRT PCR标准定量模板。方法 :提取肝瘤细胞株BEL740 2细胞总RNA ,进行RT PCR扩增并纯化AFP基因片段 ,与PMD 1 8T载体连接构建重组质粒。结果 :重组质粒的阳性克隆效率为81 .8% ,经酶切鉴定 ,目的基因片段已插入PMD 1 8T载体内。结论 :成功构建了AFPmRNA的标准定量模板 ,可应用于该基因的realtimeRT

高致病性PRRSV Nsp2变异株Power SYBR Green real time RT-PCR检测方法的建立

根据高致病性猪生殖与呼吸综合征病毒（PRRSV）Nsp2变异株Nsp2基因保守区的核苷酸序列设计合成了1对引物,建立了Power SYBR Green模式的实时荧光定量RT-PCR方法,用于检测高致病性PRRSV Nsp2变异株。以pMD-Nsp2质粒为阳性对照制作标准曲线,并对该方法的特异性、敏感性、重复性进行评价。结果显示,该方法只能检测到高致病性PRRSV Nsp2变异株的特异性扩增信号;检测线性范围广,在模板浓度为3.15×10^9-3.15×10^0copies/μL具有良好的线性关系,相关系数（r^2）为0.998;最低检测限为3.15copies/μL。对25份疑似高致病性PRRS猪病料的检测结果显示,该方法与病毒分离的符合率为100%。表明,建立的Nsp2-Power SYBR Green RT-PCR方法具有良好的特异性、敏感性和重复性。

TaqMan MGB Real-time RT-PCR检测西尼罗病毒方法的建立

目的建立一种灵敏、特异、高效的西尼罗病毒(West Nile virus,WNV)感染诊断和流行病学调查的实验室检测方法。方法用C6/36细胞培养WNV并用Vero细胞蚀斑法滴定病毒浓度;根据WNVC蛋白基因组保守序列,设计一套特异性引物和TaqMan MGB探针,用细胞培养病毒液进行方法的条件优化;用不同病毒评价方法的特异性,用系列浓度病毒稀释液和染毒蚊子评价方法的灵敏性。结果建立的TaqMan MGB Real-time RT-PCR方法可检出低于0.01PFU的WNVRNA,并可检出只含3只染毒蚊的标本;用该方法检测4种血清型登革病毒标准毒株、日本脑炎病毒、麻疹病毒、基孔肯亚病毒均为阴性。结论新建TaqMan MGB Real-time RT-PCR方法具有极高的特异性和灵敏性,是实验室早期诊断WNV感染和调查媒介携带WNV情况的理想方法。