Short Baseline Positioning with an Improved Time Reversal Technique in a Multi-path Channel

The existence of a multi-path channel under the water greatly decreases the accuracy of the short baseline positioning system.In this paper,the application of a time reversal mirror to the short baseline positioning system was investigated.The time reversal mirror technique allowed the acoustic signal to better focus in an unknown environment,which effectively reduced the expansion of multi-path acoustic signals as well as improved the signal focusing.The signal-to-noise ratio（SNR） of the time reversal operator greatly increased and could be obtained by ensonifying the water.The technique was less affected by the environment and therefore more applicable to a complex shallow water environment.Numerical simulations and pool experiments were used to demonstrate the efficiency of this technique.

Enantio-selective preparation of (S)-1-phenylethanol by a novel marine GDSL lipase MT6 with reverse stereo-selectivity

We previously functionally characterized a novel marine microbial GDSL lipase MT6 and identified that the stereo-selectivity of MT6 was opposite to that of other common lipases in trans-esterification reactions.Herein,we have investigated the use of MT6 in stereo-selective biocatalysis through direct hydrolysis reactions.Notably,the stereo-selectivity of MT6 was also demonstrated to be opposite to that of other common lipases in hydrolysis reactions.Parameters,including temperature,organic co-solvents,pH,ionic strength,catalyst loading,substrate concentration,and reaction time,affecting the enzymatic resolution of racemic 1-phenylethyl acetate were further investigated,with the e.e.of the final（S）-l-Phenylethanol product and the conversion being 97%and 28.5%,respectively,after process optimization.The lengths of side chains of 1-phenylethyl esters greatly affected the stereo-selectivity and conversion during kinetic resolutions.MT6 is a novel marine microbial GDSL lipase exhibiting opposite stereo-selectivities than other common lipases in both trans-esterification reactions and hydrolysis reactions.

Neuroprotective effects of human telomerase reverse transcriptase on beta-amyloid fragment 25-35-treated human embryonic cortical neurons

BACKGROUND： Numerous current studies have suggested that human telomerase reverse transcriptase （hTERT） gene has neuroprotective effects and can inhibit apoptosis induced by various cytotoxic stresses; however, the mechanism of action remains unknown. OBJECTIVE： To evaluate the neuroprotective effects and possible mechanism of action of hTERT gene transfection in human embryonic cortical neurons treated with beta-amyloid fragment 25-35 （AI325-35）. DESIGN, TIME AND SETTING： The randomized, controlled and molecular biological studies were performed at the Department of Anatomy and Brain Research, Zhongshan School of Medicine, Sun Yat-sen University, China, from September 2005 to June 2008. MATERIALS： AdEasy-1 Expression System was gifted by Professor Guoquan Gao from Sun Yat-Sen University, China. Human cortical neurons were derived from 12-20 week old aborted fetuses, obtained from the Guangzhou Maternal and Child Health Hospital, China. Mouse anti-Odk5 and mouse anti-p16 monoclonal antibodies （Lab Vision, USA）, and mouse anti-hTERT monoclonal antibody （Epitomics, USA）, were used in this study. METHODS： （1） Recombinant adenovirus vectors, encoding hTERT （Ad-hTERT） and green fluorescent protein （Ad-GFP）, were constructed using the AdEasy-1 Expression System. Human embryonic cortical neurons in the Ad-hTERT group were transfected with Ad-hTERT for 1-21 days. Likewise, human embryonic cortical neurons in the Ad-GFP group were transfected with Ad-GFP for 1-21 days. Human embryonic cortical neurons in the control group were cultured as normal. （2） Human embryonic cortical neurons in the Ad-hTERT group were treated with 10 pmol/L Aβ25-35 for 24 hours. Normal human embryonic cortical neurons treated with 10 pmol/Lβ25.35 for 24 hours served as a model group. Human embryonic cortical neurons in the Ad-GFP and control groups were not treated with Aβ25-35. MAIN OUTCOME MEASURES： Expression of hTERT in human embryonic cortical neurons was evaluated by immunocytochemical staining and Western blot assay. Telomerase activity was measured using a PCR-based telomeric repeat amplification protocol （TRAP） ELISA kit. Neural activity in human embryonic cortical neurons was examined by MTT assay; apoptosis was measured using TUNEL assay; and Cdk5 and p16 protein expressions were measured by Western blot. RESULTS： Expression of hTERT protein was significantly increased and peaked at day 3 post-transfection in the Ad-hTERT group. No hTERT expression was detected in the Ad-GFP and control groups. Telomerase activity was significantly greater in the Ad-hTERT group compared with the Ad-GFP and control groups （P 〈 0.01）. Compared with the control group, cell activity was significantly decreased （P 〈 0.05）, and cell apoptotic rate, Cdk5 and p16 expression were significantly increased （P 〈 0.01） in the model group. Compared with the model group, cell activity was increased in the Ad-hTERT group, and peaked at day 3 post-transfection （P 〈 0.05）. Neuroprotective effects also peaked at day 3 post-transfection; and the apoptotic rate, Cdk5 and p16 expression significantly decreased （P 〈 0.01）. CONCLUSION： Expression of hTERT in human embryonic cortical neurons can relieve Aβ25-35-induced neuronal apoptosis. The possible mechanism by which hTERT produces these neuroprotective effects may be associated with inhibition of Cdk5 and p16 expression.

Preparation and Characterization of Cathode Materials La_(0.7)Sr_(0.3-x)Ca_xCo_(0.9)Fe_(0.1)O_(3-δ) by Reverse Titration Co-Precipitation Method for ITSOFC

The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.

Micro- and nanoporous materials capable of absorbing solvents and oils reversibly： the state of the art

Treatment of petroleum spills and organic solvent pollution in general is an important issue; several techniques are under development to remove oil from water. The use of absorbents is one of the most common techniques to tackle this problem. These absorbents can be classified based on their characteristics of recyclability into irreversible and reversible ones. In this review, we discuss the application of several materials as oil absorbents, according to their classification and characteristics such as hydrophobicity, surface area and oil absorption capacity. Also, the fabrication methods for some materials are presented and analyzed.

Reverse Solution and Parametric Design of the Conjugate Cam Weft Insertion Mechanism Based on VB.NET and UG

In order to realize the parametric design of the conjugate cam weft insertion mechanism,according to the necessary parameters of weft insertion process,ideal kinematic curves of the weft insertion mechanism were given,and the mathematical model of reverse solution for this mechanism was established.The parameters of this mechanism were obtained by reverse solution on the basis of the given ideal kinematic curves and kinematic requirements.The parametric design platform which was integrated with the functions of parametric reverse solution,motion simulation,three-dimensional modeling and virtual assembly was developed based on VB.NET and Unigraphics(UG) NX.After entering the technological parameters of weft insertion process and essential structural parameters by users,three-dimensional drawing of the main parts such as the conjugate cam and shaft,can be obtained by this platform,also the processing data of the cam can be calculated.This platform provides a rapid approach for parametric design of weft insertion mechanism.

“E骨”-反肩置换术一站式术前规划系统

目的为提高反肩置换术术前规划的精准度和效率,本研究开发了“E骨”—反肩置换术一站式术前规划系统。方法利用nnU-net深度神经网络进行肩胛骨分割,获得精确的肩胛骨分割结果;结合骨密度、上下倾角和入钉长度3个关键因素自动定位基座,并计算出手术规划所需定量参数;结合关节盂形态和基座定位信息生成个性化导板;编写系统界面,将各部分功能模块化组装便于使用,提供交互操作与规划结果显示的功能。结果构建出“E骨”术前规划系统。本系统与Mimics系统相比,减少了规划过程中繁琐的手动调整,平均入钉长度规划结果长于Mimics系统,且规划时间缩短86%。本系统肩胛骨分割精度达到99.93%,较Mimics更高。结论本研究为反肩置换术提供了一套一站式的高效、精准的术前规划方案,具有广泛的临床应用前景。

Differential interformational velocity analysis as an effective direct hydrocarbon indicator under velocity reversal conditions,an example from the anomalously high temperature and over-pressured DF1-1 Gas Field in the Yinggehai Basin,South China Sea

In the DF1-1 Gas Field in the Yinggehai Basin, South China Sea, the velocity-depth plot and velocity spectra show significant variations from a linear trend, exhibiting a distinct reversal phenomenon. Velocity parameters derived from velocity spectral analysis of the seismic data and sonic logs indicate that the interval velocity reverses below 2,100 m (2.2 s two-way time (TWT)) in the DF1-1 Gas Field. Some direct hydrocarbon indicators (DHIs) models developed for the shallow strata cannot be simply applied to the moderately to deeply buried strata for direct exploration target recognition because the velocity reversal has caused the middle-deep gas reservoirs to exhibit a moderate or weak seismic amplitude. The hydrocarbon indicator method of “Differential Interformational Velocity Analysis (DIVA)” with the aid of other hydrocarbon indicating techniques was employed to effectively identify DHIs in the middle-deep strata under velocity inversion. The result has shown that the DIVA technique can be effectively used as a DHI in both the shallow and the middle-deep strata in the study area with the shallow strata characterized by Type I DIVA anomaly and the middle-deep strata characterized by the Type II DIVA anomaly.

Remote positioning system based on GPS/GPRS

Considering the need of target positioning,a remote positioning system is designed based on global positioning system(GPS)and general packet radio service(GPRS);The data collection terminal is based on microcontroller unit(MCU)PIC24FV301.It uses GPRS network to create wireless link and transmits GPS source information which is collected by LEA-5H board to monitor center on the Internet.The monitor center obtains the target information through processing and analysis of the calculated data.Actual operation results indicate that the designed system has excellent performance and achieves the goal of the remote location.

土地确权能够优化农户农地质量保护行为吗?--基于苹果户正向行为和逆向行为的再检验

基于黄土高原苹果产区苹果户的调查数据,探析农地确权对农户农地质量保护中正向行为和逆向行为的影响。研究表明:农地确权有效促进了苹果户的正向行为投入,该促进作用主要体现于投资回报期限较长的正向行为,且主要通过安全效应实现;但农地确权并未促使农户减少逆向行为投入,反而对逆向行为农药投入产生正向影响。PSM模型、工具变量法和替代变量法检验结果依然支持该结论。进一步讨论还发现,农户损失厌恶、风险规避、路径依赖心理和有效替代行为缺乏是造成农地确权未对农户逆向行为形成负向激励的主要原因。需通过促进替代行为对逆向行为的有效替代和完善农业要素市场,强化农地确权对农地质量保护行为的优化作用。

一种新型的三自由度3-RRRRR并联平台机构及其位置分析

提出一种新型的 3 -RRRRR并联机构 ,并建立了其位置反解方程。首先用反螺旋分析了 3 -RRRRR并联机构在初始位置下和在一般情况下的瞬时运动特性。得出该机构在初始位置下和在一般情况时 ,机构有沿x、y、z轴方向的三个移动自由度 ,即初始位置下发生移动后 ,该机构还有 3个移动自由度。其次用D-H法给出了主动输入 (θ1)与动台位姿的关系 ,给出了该机构的位置反解公式 ,并进行了验证 ,绘制了工作空间的形状。该机构可进一步作为微动机构应用。

持续气道正压对高龄肺癌患者单肺通气中肺泡灌洗细胞IL-1β和IL-8 mRNA表达的影响

目的观察持续气道正压(continuous positive airway pressure,CPAP)对高龄肺癌患者单肺通气(one-lung ventilation,OLV)中非通气侧肺泡灌洗细胞IL-1β和IL-8mRNA的表达,在分子水平上探讨CPAP对肺炎性反应的影响。方法选择单肺通气下年龄>65岁的肺癌开胸手术患者28例,ASAⅠ～Ⅱ级,随机分为对照组(n=14)和CPAP组(n=14)。对照组在麻醉期间非通气侧肺的支气管导管直接开口于大气中,CPAP组麻醉期间非通气侧肺持续给予CPAP(压力3～5cmH2O,1cmH2O=1.02Pa)。在单肺通气开始和通气2h后分别对两组患者非通气侧肺用纤维支气管镜行支气管肺泡灌洗(bronchoalveolar lavage,BAL),从灌洗液中收获细胞提取RNA,逆转录合成cDNA,以-βactin为内标准作PCR后电泳扫描求积,检测肺泡灌洗细胞IL-1β和IL-8mRNA的表达。结果单肺通气2h后,对照组比CPAP组非通气侧肺肺泡灌洗液中IL-8和IL-1βmRNA的表达显著增加(P<0.01)。结论单肺通气中非通气侧肺给予适度的CPAP可以有效减少高龄肺癌患者肺泡灌洗细胞促炎性细胞因子mRNA的表达水平,抑制肺局部炎症反应,对非通气侧肺可能有一定的保护作用。

一种新型少自由度并联机构4-RPR(RR)及基础分析

讨论了一种新型少自由度并联机构4-RPR(RR),描述了机构的特性,计算了自由度,给出了机构的位置反解,利用虚设机构法建立了一阶影响系数矩阵并对机构进行了速度分析及仿真验证。这些是对该机构进一步分析的基础,因此具有实际的价值。

3-PSS/S三转动并联机器人机构的位置分析

根据并联机器人机构结构综合理论,提出了一种新型的能实现三维转动的空间3-PSS/S三自由度并联机构。该机构的动角台和定角台通过3个具有移动副的PSS约束支链和1个中间球铰连接。动角台为3个棱边互相垂直的正三棱锥,定角台上3个导轨的轴线互相垂直。应用坐标变换法,推导了完全封闭形式的位置正、反解。最后,应用实例验证了理论分析的正确性。

非常规条件下超深漏失井尾管固井作业——以云安002-7井为例

四川盆地东部云安厂构造云安002-7井φ177.8mm尾管固井集超深井、大斜度井、高压气井和窄安全密度窗口于一身。φ215.9mm井眼段经长时间、多次堵漏,消耗了大量钻井液(1 418.1m3),仍未达到常规固井作业的不溢不漏、通井畅通、井眼清洁等要求,已难提高井筒承压能力。井眼状况表现出漏层多且位置不确定、液面不在井口、气层多、钻井液密度高(1.80g/cm3)、裸眼段长(2 538.28m)且井眼轨迹复杂等特点。为此,针对下套管过程中的出口不返、不具备分段循环条件、无法排后效、尾管悬挂器可能提前坐挂等技术难点,采取了针对性的下套管作业防阻卡、保水眼畅通以及正注反挤工艺保环空水泥浆对接等三大技术措施,确保了尾管安全顺利下至设计井深。测井解释结论表明:φ215.9mm井眼段的高压气层得到了有效封固,固井质量可满足下一步安全钻井作业需要。该井φ177.8mm尾管固井的成功为今后类似复杂气井固井作业提供了有力的技术支持。

郑州市23例SARS-CoV-2核酸单靶标阳性标本的跟踪检测分析

目的对郑州市23例严重急性呼吸综合征冠状病毒2(SARS-CoV-2)核酸单靶标阳性标本进行跟踪检测分析,为实验室检测提供参考。方法按照《新型冠状病毒肺炎防控方案》采集新型冠状病毒肺炎(COVID-19)疑似患者的鼻拭子或咽拭子,提取SARS-CoV-2核酸并采用实时荧光逆转录聚合酶链反应(RTPCR)检测。对6例开放读码框1ab(ORF1ab)基因单靶标阳性和17例核壳蛋白(N)基因单靶标阳性患者进行重新采样检测。结果首检23例SARS-CoV-2核酸单靶标阳性的标本中有8例疑似病例在随后的重新采样检测中被确认为SARS-CoV-2核酸阳性,重新采样检测阳性率为34.78%。结论 COVID-19同种类型标本2次采样检测中均出现单靶标阳性的检测结果时,应该慎重对待,建议重新采样跟踪检测。

2-UPS/(S+SPR)R并联机构伴随运动与正反解分析

目的分析含有闭环单元的三自由度2-UPS/(S+SPR)R并联机构是否具有伴随运动,并对该机构的位姿正逆解进行分析。方法利用欧拉变化得到旋转矩阵,结合机构的结构特性建立约束方程,分析机构是否具有伴随运动和机构的位姿逆解。利用粒子群(PSO)算法分析机构的位姿正解。结果该机构不具备z轴方向的转动伴随运动,建立了位姿逆解方程;通过PSO算法在输入驱动参数的情况下,可以精确地得到动平台的位姿。结论机构不存在伴随运动,通过PSO优化算法得到了位姿正解精确的数值解,为分析机构的工作空间提供了良好的基础。

False Positives Caused by Single Primer in DDRT Analysis of Soybean

[Objective] The aim was to explore the reasons of false positives in Different Display Reverse Transcription（DDRT）analysis.[Method] Soybean varieties ＂Jilin 30＂ and ＂Tongnong 13＂ were used as materials to carry out analysis on false positives in DDRT analysis.[Result] An important origin of false positives appeared in DDRT analysis was the non-specific amplification caused by the combination of single primer and cDNA.The parallel PCR test of single primer should be set so as to verify whether the obtained fragments were the false positives or the PCR productions combined with single primer.[Conclusion] This study had provided basis for improving the success rate of DDRT experiment.

蓝粒小麦花青素合成途径中的查尔酮合酶基因和类黄酮3＇5＇-羟化酶基因3＇末端的克隆和表达分析

采用RT-PCR和RACE方法从蓝粒小麦(Triticum aestivum L.×Thinopyrum ponticum(Podp.)Z.W.Liu et R.R.-C.Wang)发育种子中克隆到两个查尔酮合酶基因(TaCHS.tl，TaCHS．wl)，分别编码394个氨基酸，二者核苷酸和氨基酸序列的同源性分别为96．0％和98．9％；而且克隆到一个类黄酮3'5’．羟化酶基因(F3'5'H)3’-末端。分别从长穗偃麦草(Thinopyrum ponticum(Podp．)Z．W．Liu et R．R．-C．Wang)、蓝粒小麦、白粒小麦和中国春基因组中分离到查尔酮合酶基因(CHS)的全长序列(ThpCHS.tg TaCHS．wg，TaCHS．csg)，它们的核苷酸序列之间具有很高的同源性，且均含有一个内含子(intron)，序列差异主要在内含子。通过DNA序列比较，发现一个CHS与亲本之一的长穗偃麦草基因组同源性达100％，一个CHS与另一白粒亲本基因组同源性达99％，表明来自于父、母本的CHS在蓝粒发育的种子中均表达。Southerm杂交结果表明CHS在小麦中的拷贝数至少有4个，不同颜色的蓝粒小麦、白粒小麦间拷贝数基本一致，但都与长穗偃麦草有差异，根据以上结果初步判定CHS在蓝粒小麦中属于一个多基因家族。Reverse Northern分析表明CHS在开花后15d发育的蓝粒小麦中具有较强的表达；花后21d F3'5'H和DFR的转录本积累显著高于CHS，基本上检测不到CHS的表达。这三个基因在蓝粒小麦中的表达顺序与其他植物花青素合成途径中的基因表达次序一致：ChS先于F3'5'H，F3'5'H先于DFR。实验还表明F3'5'H和DPR在幼叶中表达也较强，CHS仅在发育种子中表达，具有组织特异性。花后21d，F3’5’H在白粒、蓝粒小麦和中国春种子中均强烈表达，蓝粒小麦CHS和DFR转录本比白粒小麦多。因此，认为在蓝粒小麦中存在花青素生物合成途径，在蓝色色素形成过程中，该途径中的结构基因受到调节基因的调控。

云南某混合型胶磷矿正-反浮选工艺技术试验研究

以云南某中低品位混合型胶磷矿为研究对象,进行了工艺矿物学和可选性研究。采用常温正反浮选工艺流程,自制水玻璃和捕收剂,通过磨矿细度试验,调整剂、捕收剂用量试验等,确定了最佳的浮选工艺和试验条件。在原矿w(P_(2)O_(5))19.56%、w(MgO)2.83%、常温条件下,采用正-反浮选工艺流程:开路实验,可得到精矿指标为w(P_(2)O_(5))28.79%、w(MgO)0.94%,精矿回收率73.44%;闭路试验,取得精矿w(P_(2)O_(5))28.87%、w(MgO)0.92%、回收率81.78%、尾矿w(P_(2)O_(5))8.13%的指标。为该矿的工业利用打下了坚实的试验基础。