等位基因特异性引物和TaqMan-MGB探针双抑制野生等位基因扩增的实时荧光定量PCR检测JAK2V617F突变率

本研究建立在外周血基因组DNA中定量检测JAK2V617F突变率的荧光定量PCR检测方法并探讨其临床应用价值。在实时荧光定量PCR分析系统中,应用等位基因突变引物和等位基因野生TaqMan-MGB探针共同抑制JAK2V617F野生等位基因扩增,从而特异性地扩增JAK2V617F突变等位基因。通过测定不同JAK2V617F突变率标准品及其循环阈值(Ct值),建立JAK2V617F突变率定量测定方法,并对89例表观健康人外周血基因组DNA中JAK2V617F突变率进行检测。结果表明,建立的方法定量检测JAK2V617F突变率的下限为0.1%,检测JAK2V617F突变率的批内、批间平均变异率分别为4.1%和6.1%。对89例表观健康人外周血基因组DNA中JAK2V617F突变率检测显示,其中2例为JAK2V617F阳性,突变率分别为0.64%和0.98%。结论:建立的JAK2V617F突变率定量检测方法具有检测灵敏度高和重复性好的特性,适合骨髓增殖性疾病的诊断及疾病进程和疗效监测。本方法检测原理可用于各种单碱基突变率的检测,具有广泛的应用前景。

施加扩散梯度的双抑脂SPACE序列在节后臂丛神经成像的研究

目的:研究施加扩散梯度的双抑脂SPACE序列在显示节后臂丛神经的临床可行性。方法:对26名无臂丛神经损伤病史的志愿者同时行常规SPACE-TIRM序列和施加扩散梯度的双抑脂SPACE序列扫描,对比2种序列对节后臂丛神经显示效果的差异并计算2组序列所得图像的信噪比(SNR)和对比噪声比(CNR)。结果:施加扩散梯度的双抑脂SPACE序列对节后臂丛神经的显示较常规SPACE-TIRM序列显示神经的SNR差异无统计学意义;神经-肌肉的CNR明显高于常规SPACE-TIRM序列(P<0.05)。施加扩散梯度双抑脂SPACE序列减轻了慢血流信号对神经的干扰,对节后臂丛神经的显示效果优于常规SPACE-TIRM序列。结论:施加扩散梯度的双抑脂SPACE序列对节后臂丛神经的显示方面更具有优势,具有良好的应用前景。

Research on the Factors Affecting Nitrification Inhibition of Dicyandiamide(DCD) in Latosol

[Objective] This research aimed at studying the effects of application amount of DCD and physics and chemistry characteristics of soil such as temperature,moisture content,organic matter content and pH on the inhibition of nitrification when applying nitrification inhibitor DCD in latosol.[Method] The experiment was carried out under aerobic incubated conditions.[Result] A significant delay period of nitrification was observed when the application amount of DCD was 10 mg/kg soil,and the inhibition can at least last for 56 d.When the cultural temperature had increased from 10 to 30 ℃,the duration of nitrification inhibition was shortened from 90 to 30 d.The nitrification inhibition of DCD was reduced with the increasing soil moisture content,organic matter content and soil pH,while the duration of nitrification inhibition was prolonged with the decreasing soil moisture content,organic matter content and soil pH.[Conclusion] Nitrification inhibition of DCD can be improved by increasing the application amount or reducing soil temperature,moisture content,organic matter content and pH.

NOVEL MICROSTRIP DUAL-MODE BANDPASS FILTER WITH COUPLING ENHANCEMENT AND WIDEBAND SPURIOUS RESPONSE SUPPRESSION

The microstrip dual-mode filter （DMF） with conventional coupling structure has some limitations in- eluding the port coupling strength limited by fabrication tolerance and the existence of serious second order spuri- ous band. Therefore, a novel DMF with a offset-feed bended coupling structure and a stepped-impedance dual- mode resonator is proposed for coupling enhancement and spurious response suppression. Based on the analysis of the change of spur frequencies and the current distribution of spur resonant modes, all spurs near passband of the cascaded DMF can be fully suppressed by optimizing the structure parameters of parasite resonators, which bene- fits from the inherent well-controlled transmission zeros. Experimental results show that the proposed DMF ex- hibits lower insertion loss ,much sharper rate of cutoff and wider spur-free stop band compared with conventional DMF. This design is applicable for spur suppression in wideband communication.

DISCRETE BIDIRECTIONAL ASSOCIATIVE MEMORY WITH LEARNING FUNCTION

In this paper we propose a new discrete bidirectional associative memory (DBAM) which is derived from our previous continuous linear bidirectional associative memory (LBAM). The DBAM performs bidirectionally the optimal associative mapping proposed by Kohonen. Like LBAM and NBAM proposed by one of the present authors,the present BAM ensures the guaranteed recall of all stored patterns,and possesses far higher capacity compared with other existing BAMs,and like NBAM, has the strong ability to suppress the noise occurring in the output patterns and therefore reduce largely the spurious patterns. The derivation of DBAM is given and the stability of DBAM is proved. We also derive a learning algorithm for DBAM,which has iterative form and make the network learn new patterns easily. Compared with NBAM the present BAM can be easily implemented by software.

Suppression of RNA Interference Pathway in vitro by Grass Carp Reovirus

The means of survival of genomic dsRNA of reoviruses from dsRNA-triggered and Dicer-initiated RNAi pathway remains to be defined. The present study aimed to investigate the effect of Grass carp reovirus (GCRV) replication on the RNAi pathway of grass carp kidney cells (CIK). The dsRNA-triggered RNAi pathway was demonstrated unimpaired in CIK cells through RNAi assay. GCRV-specific siRNA was generated in CIK cells transfected with purified GCRV genomic dsRNA in Northern blot analysis; while in GCRV-infected CIK cells, no GCRV-specific siRNA could be detected. Infection and transfection experiments further indicated that replication of GCRV correlated with the increased transcription level of the Dicer gene and functional inhibition of in vitro synthesized egfp-siRNA in silencing the EGFP reporter gene. These data demonstrated that although only the genomic dsRNA of GCRV was sensitive to the cellular RNAi pathway, unidentified RNAi suppressor protein(s) might contribute to the survival of the viral genome and efficient viral replication.

NOVEL BIPHASE CODE-INTEGRATED SIDELOBE SUPPRESSION CODE

A kind of novel binary phase code named sidelobe suppression code is proposed in this paper. It is defined to be the code whose corresponding optimal sidelobe suppression filter outputs the minimum sidelobes. It is shown that there do exist sidelobe suppression codes better than the conventional optimal codes-Barker codes. For example, the sidelobe suppression code of length 11 with filter of length 39 has better sidelobe level up to 17dB than that of Barker code with the same code length and filter length.

Inhibition of Two-Photon Absorption in a Four-Level Atomic System with Closed-Loop Configuration

We theoretically investigate the features of two-photon absorption in a coherently driven four-level atomic system with closed-loop configuration. It is found that two-photon absorption can be completely suppressed just by properly adjusting the relative phase of four coherent low-intensity driving fields and the atomic system becomes trans- parent against two-photon absorption. From a physical point of view, we explicitly explain these results in terms of quantum interference induced by two different two-photon excitation channels.

Mechanism of aluminum corrosion in LiFSI-based electrolyte at elevated temperatures

Lithium bis(fluorosulfonyl)imide(LiFSI) is a promising replacement for lithium hexafluorosphate due to its excellent properties. A solution to the corrosion of aluminum(Al) current collectors by LiFSI at elevated temperatures is essential. The mechanisms of Al corrosion in LiFSI-based electrolyte at 45 ℃ were studied with density functional theory calculations and spectroscopic investigations. It is found that the irregular, loose and unprotected AlF3 materials caused by the dissolution of co-generated Al(FSI)3 can exacerbate Al corrosion with the increase of temperature. Lithium bis(oxalate)borate(LiBOB) can effectively inhibit the Al corrosion with a robust and protective interphase;this can be attributed to the interfacial interactions between the Al foil and electrolyte. Boron-containing compounds promote the change from AlF3 to LiF, which further reinforces interfacial stability. This work allows the design of an interface to Al foil using LiFSI salt in lithium-ion batteries.

Depressing behaviors and mechanism of disodium bis(carboxymethyl) trithiocarbonate on separation of chalcopyrite and molybdenite

This work focuses on the organic depressant,disodium bis(carboxymethyl)trithiocarbonate(DBT),as a selectivedepressant in copper?molybdenum sulfide flotation separation.Micro-flotation,Zeta potential,FTIR and XPS measurements werecarried out to investigate the selective depression mechanism of DBT on chalcopyrite.Zeta potential and FTIR measurementsrevealed that DBT had higher affinity for chalcopyrite than molybdenite and the XPS results of chalcopyrite before and aftertreatment with DBT further proved that DBT adsorbed on chalcopyrite surface.The investigation indicates that the mechanism ofDBT adsorbing on chalcopyrite is mainly physical adsorption.Locked circuit experiments were carried out and the results showedthat DBT could be considered as a cleaner option in commercial Cu?Mo flotation separation circuits.

Flotation techniques for separation of diaspore from bauxite using Gemini collector and starch depressant

The floatability of diaspore and three kinds of silicate minerals,including kaolinite,illite and pyrophyllite,by a cationic Gemini surfactant as collector and starch as depressant was investigated as function of reagents concentration and pulp pH.Further studies of artificially mixed minerals and bauxite ore were also detailedly conducted.At last,the pre-desliming reverse flotation separation process was adopted.It can be concluded that the combinational use of a Gemini cationic collector and the starch depressant is effective.The concentrates with Al2O3 to SiO2 mass ratio of 9.66 and the recovery of Al2O3 of 71.73% are obtained from natural bauxite ore(A/S=5.70) at pH value of around 10.

Inhibitory effect of metformin on the proliferation of human hepatoma HepG2 cells and its potential mechanism

Objective： This work aimed to study the inhibitory effect and the related mechanism of metformin （MET） on the proliferation of human hepatoma HepG2 cells. Methods： Human hepatoma HepG2 cells were treated with MET （0, 2, 10, and 50 mM）. The inhibitory effect of MET on the proliferation of HepG2 cells was determined by MTT method. The apoptosis of HepG2 cells was detected by flow cytornetry. The expression of cyclin D1 in HepG2 cells was examined by Western blot. ROS-DHE fluorescence probe was used to stain the reactive oxygen species （ROS） generated by HepG2 cells after treat- ment. Results： MET could inhibit the proliferation of HepG2 cells in a dose and time dependent manner. MET promoted the apoptosis of HepG2 cells. In addition, MET suppressed the expression of cell cycle protein cyclin D1 and induced the produc- tion of ROS in HepG2 cells. Conclusion： MET can inhibit the proliferation of human hepatoma HepG2 cells and induce cell apoptosis. Meanwhile, MET has the ability to decrease the expression of cyclin D1 and induce ROS generation, which may be involved in the mechanism of inhibiting hepatoma cells proliferation.

Application of a yeast two-hybrid based screening system in the identification of amyloid-beta aggregation inhibitors in pharmaceutical plants

The aggregation of amyloid-beta （Aβ） peptide, has been demonstrated to be critical for the development of Alzheimer＇s disease （AD）. All aggregation inhibitors are thus considered to be drug candidates for AD therapy. In the present study, we developed a novel screening tool based on the yeast two-hybrid system to screen Aβ aggregation inhibitors. The human Aβ42 peptide cDNA was cloned using assembly PCR and inserted into each of the yeast expression plasmids containing either the GAL4 activation domain （GAL4AD） or the DNA-binding domain （GAL4BD）. Co-transformation of the above plasmids led to the expression of the fusion proteins GAL4AD-Aβ42 and GAL4BD-Aβ42 in the AH 109 yeast strain. The self interaction of Aβ42 fragments reconstructed the GAL4 transcriptor and thus activated the GAL4 responsive transcription of four reporter genes including HIS3, ADE2, lacZ and MEL1. The expression of the reporter genes rendered the multiple auxotrophic yeast cells capable of growing on the synthetic SD media lacking adenine and histidine. Growth arrest was used as a marker for screening Aβ aggregation inhibitors in this system, and the evaluation of Rhodiola species revealed potential resources for the development of Aβ aggregation inhibitors.

Design, synthesis and activity evaluation of novel pyridinone derivatives as anti-HIV-1 dual(RT/IN) inhibitors

Three series of novel anti-immunodeficiency virus 1 （HIV-1） dual （RT/1N） inhibitors were rationally designed by introducing a functioning diketo acid （DKA） into pyridin-2-one scaffold. To efficiently analyze inhibitory activity, these compounds were screened against HIV-1 RT and IN respectively via surface plasmon resonance （SPR）, and active compounds were subsequently evaluated by enzyme assay. It was noteworthy that compound A2 exhibited moderate activity against both HIV-1 RT and IN. This result provided information for further development of pyridinone analogues as potent dual HIV-1 inhibitors.

Construction and analysis of the c DNA subtraction library of yeast and mycelial phases of Sporothrix globosa isolated in China: identification of differentially expressed genes

Species included in the Sporothrix schenckii complex are temperature-dependent with dimorphic growth and cause sporotrichosis that is characterized by chronic and fatal lymphocutaneous lesions. The putative species included in the Sporothrix complex are S. brasiliensis, S. globosa, S. mexicana, S. pallida, S. schenckii, and S. lurei. S. globosa is the causal agent of sporotrichosis in China, and its pathogenicity appears to be closely related to the di- morphic transition, i.e. from the mycelial to the yeast phase, it adapts to changing environmental conditions. To determine the molecular mechanisms of the switching process that mediates the dimorphic transition of S. globosa, suppression subtractive hybridization （SSH） was used to prepare a complementary DNA （cDNA） subtraction library from the yeast and mycelial phases. Bioinformatics analysis was performed to profile the relationship between dif- ferently expressed genes and the dimorphic transition. Two genes that were expressed at higher levels by the yeast form were selected, and their differential expression levels were verified using a quantitative real-time reverse transcriptase polymerase chain reaction （qRT-PCR）. It is believed that these differently expressed genes are involved in the pathogenesis of S. globosa infection in China.

Bi-conjugate gradient based computation of weight vector in space-time adaptive processing

Dear editor,Space-time adaptive processing(STAP)techniques can effectively suppress strong ground clutter and detect moving target for airborne phased array radar by combing spatial signals and the temporal pulses simultaneously[1].It is known that,when the clutter satisfies the independent and identically-distributed(i.i.d.)condition,the sample matrix inversion(SMI)-based STAP[1]requires twice the number of degree of freedom