S/N Ratio of 4-Channel A/D Geological Radar Non-uniform Sampling Signals

Using the quantitative error probability density method we studied the S/N ratio of alternately sampled signals digitized by a 4-channel A/D. A complete expression for the S/N ratio of a 4-channel A/D non-uniform sampling signal was deduced. First we obtained an expression for the S/N ratio of a 1-channel A/D uniform sampling signal when the sampling frequency was equal to or greater than 2 times the frequency of the sampled signal. Based on the S/N ratio of a 2-channel A/D,alternating,non-uniform sampling signal,we analyzed the distribution of quantitative error using the quantitative error probability density method and the distribution convolution formula. From this the S/N ratio expression of a 4-channel A/D sampling signal was deduced. The simulation result shows that the deduced expression is correct.

Numerical Study of φ^4 Model by Potential Importance Sampling Method

We investigate the phenomena of spontaneous symmetry breaking for φ^4 model on a square lattice in the parameter space by using the potential importance samplingmethod, which was proposed by Milchev, Heermann, and Binder [J. Star. Phys. 44 （1986） 749]. The critical values of the parameters allow us to determine the phase diagram of the model. At the same time, some relevant quantifies such as susceptibility and specific heat are also obtained.

The Topology Sampling of H2SO4·NH3 with Meta-Dynamics Method

The configurations of molecular clusters have significant impacts on their growth into fine particles in atmosphere.In this paper,we explore the topology space of the structure of H2SO4·NH3 dimer with a novel sampling technique of meta-dynamics(MTD)method and ab initio molecular dynamics simulations.The simulations are carried out at the temperatures of both 50 K and 242 K,which represent the typical high and low latitudes of troposphere.The results show that,compared with only traditional MD simulations,the structure samplings are significantly accelerated with MTD method.Therefore,more isomers of the dimer are discovered within the same simulation time scale.In addition,the results show that MTD is more efficient for circumstances with high temperature.

输尿管镜碎石术后发热性尿路感染危险因素及血清β防御素2高迁移率族蛋白B1 Toll样受体4早期预测价值

目的 探讨泌尿结石疾病采取输尿管镜碎石术治疗术后发生发热性尿路感染的相关危险因素,观察血清β防御素2、高迁移率族蛋白B1(HMGB1)以及Toll样受体4(TLR4)对早期预测尿路感染的价值。方法 回顾性分析122例行输尿管镜碎石术治疗者的临床资料,根据术后是否发生发热性尿路感染分成感染组与未感染组,记录患者资料,分析危险因素,此外采集2组血液分离血清,测定血清β防御素2、HMGB1、TLR4水平。结果 术后35例(28.7%)发生发热性尿路感染,多因素分析显示年龄≥60岁、手术时间≥60 min、泌尿道手术史、合并糖尿病、导尿管留置时间≥72 h、住院时间≥7 d均是输尿管镜碎石术患者术后发热性尿路感染独立危险因素(P=0.023、0.014、0.016、0.019、0.008、0.011,OR值=2.154、3.021、2.451、2.331、2.025、2.415);感染组血清β防御素2、HMGB1、TLR4检测水平高于未感染组(t=10.48、28.47、22.86,P<0.05)。结论 输尿管镜碎石术,年龄、手术时间、泌尿手术室、合并糖尿管、导尿管留置与住院时间为术后发热性尿路感染的相关危险因素,需加强防范,术后通过检测血清β防御素2、HMGB1、TLR4水平对早期预测感染价值突出,值得推广。

功能性Fe_(3)O_(4)纳米颗粒在痕量农药残留分析中的应用研究进展

未被有效利用的农药经环境与膳食暴露,可能影响食品安全,进而在人体内形成微量残留,成为危害人体健康的潜在因素。相较环境水及水果蔬菜等常规样品而言,由于人体样本具有复杂的基质效应及农药痕量残留水平的特点,包括液-液萃取和固相萃取等在内的传统样品前处理方法很难实现对复杂基质中不同种类痕量农药的检测分析。为了解决复杂基质样本中痕量农药检测的难题,靶向性的纳米吸附剂被陆续开发出来。本文介绍了具备高效分离特性的纳米吸附剂——功能性Fe_(3)O_(4)纳米颗粒用于痕量农药残留分析的技术趋势,包括其磁核合成方式(化学共沉淀、热分解、溶剂热反应等)、功能基团修饰类型(天然高分子聚合物、碳基材料、金属有机框架材料和无机材料等)、应用基质(环境水、水果蔬菜及生物样本)以及适用农药种类和检测分析效率;重点介绍了该类纳米颗粒的靶向性制备原理、应用特点和最新研究进展,分析了目前基于功能性Fe_(3)O_(4)纳米颗粒分析痕量农药过程中尚待改进的问题和未来应用前景,以期为新型纳米吸附方法的拓展性应用提供理论参考。

生姜荧光碳量子点的制备及对水样中MnO_(4)^(-)的高灵敏度检测

以生姜为原料,采用水热法制备了荧光碳量子点(CQD)。通过透射电镜(TEM)、X射线光电子能谱(XPS)、红外光谱(FT-IR)、荧光光谱以及紫外吸收光谱(UV-Vis)等手段对制备的CQD进行了表征,探索了CQD对MnO_(4)^(-)的检测。结果表明:在180℃,12h的条件下制备的生姜CQD的平均粒径为2.4nm,且具有很好的分散性。CQD的荧光可被MnO_(4)^(-)有效猝灭,且猝灭程度与MnO_(4)^(-)浓度在0~1000μmol/L范围内呈良好的线性关系,R^(2)=0.991,检测限低至0.059μmol/L。将此CQD用于环境水样中MnO_(4)^(-)的检测,回收率为94.72%~113.36%,结果较好。所建立的荧光方法具有简单、分析速度快、选择性好和成本低的优点。

《英语国家概况》辅导(19)——Sample Test 4

一、单项选择题(25％) Read the following unfinished statements or ques-tions carefully. For each unfinished statement or ques-tion four suggested answers A, B, C and D are given.Choose the one you think best completes the statementor answers the question:1.The British Empire gradually disappeared and it was replaced by the____.

《英语国家概况》辅导(20) Sample Test 4(英文)

四、名词解释(15%)Explain the following terms in English:1.Jazz 2.Fianna Fail3.Counterculture 4.The Privy Council5.“Quiet Revolution”五、简答题(12%)Give brief answers to the following questions;1.What do you know about the“public schools”in the UK?2.What are the powers of the U.S.President?3.What is meant bv the term“welfare state”inBritain?

4 F MPA1导管经右肘静脉完成双侧肾上腺静脉同步采血术1例

探讨4 F MPA1导管经右肘静脉行双侧肾上腺静脉同步采血术(AVS)的安全性和可行性。选择1例右肾上腺中央静脉汇入副肝静脉的原发性醛固酮增多症患者,经右上肢贵要静脉、头静脉处分别置入2个6 F鞘管,选择2根4 F MPA1导管(1根塑形成猪尾状),分别插入左右肾上腺静脉,分3个时间段同步采集双侧肾上腺静脉及外周静脉血样,检测醛固酮、皮质醇激素水平。肾上腺静脉醛固酮/皮质醇:左侧13.2,右侧2.9,左侧优势指数9.9,左肾上腺为醛固酮优势分泌侧。4 F MPA1导管经右肘静脉行同步AVS具有技术可行、导管选择简单、创伤小、安全性高、不需卧床制动等优点。

Factors Associated with Sample Rejection for CD4+/CD8+ T Cell Count Analyses at the Kenyatta National Hospital Comprehensive Care Center Laboratory, Kenya

Background: The appropriate time to initiate antiretroviral therapy (ART) in HIV/AIDS patients is determined by measurement of CD4+/CD8+ T cell count. The CD4/CD8+ T cell count is also useful, together with viral load, in monitoring disease progression and effectiveness treatment regimens. Several factors may contribute to sample rejection during the CD4+/CD8+ T cells count, resulting in negative effects on patient management. Objective: Evaluate the causes for CD4+CD8+ T cell count sample rejection at the Kenyatta National Hospital Comprehensive Care Center Laboratory. Method: A retrospective cross-sectional study was conducted between 2018 and 2020. Data was obtained from the “rejected samples” for PartecR FlowCyp flow cytometry file. Designed data collection sheet was used for data capture. A total of 3972 samples were submitted for CD4+/CD8+ T cell count during the study period. Causes for sample rejection were numbered 1 to 12, each representing a reason for sample rejection. Number 1 was sub-categorized into clotted, hemolyzed, short-draw and lipemic. Data was analyzed using excel, and presented using tables, graphs and pie charts. Approval to conduct the study was obtained from KNH/UoN ERC. Results: In the study period, 81/3972 (2.0%) samples were rejected. Samples submitted more than 48 hours after collection were mostly rejected. Other factors included improper collection technique, delayed testing, patient identification error and incorrect use of vacutainer. A combination of clotted samples, specimen submission more than 48 hours caused the most frequent sample rejection, followed with combination of specimen submission more than 48 hours, delayed testing and delayed specimen processing. Together, clotted samples, incorrect vacutainer and poor specimen label caused the least sample rejection. Conclusion: Sample rejection rate for CD4/CD8+ T cell count was relatively low, and multiple factors contributed to rejection. However, improved quality assurance will enable more benefit to patients who seek this test in the laboratory.

4-(2-噻唑偶氮)连苯三酚光度法测定钢样中钛(Ⅳ)

在溴化十六烷基三甲基铵存在下，用分光光度法研究了4-（2-噻唑偶氮）连苯三酚与钛㈣的显色反应性能。结果表明：在pH2．0～5．0氯乙酸-氯乙酸钠缓冲溶液条件下，4-（2-噻唑偶氮）连苯三酚与钛㈣形成摩尔比为2：1的红色络合物，其最大吸收波长λmax为560nm，在25mL显色液中钛量在0～20μg范围内服从比尔定律，相关系数r=0．9990，测定的表观摩尔吸光系数ε560=4．07×10^4L·mol^-1·cm^-1，方法成功应用于钢样品中微量钛的测定，结果同认定值相符。

间接竞争ELISA方法测定水中2,4-D的研究

以2,4-D-BSA为包被抗原,采用自行制备的2,4-D单克隆特异性抗体6D11建立了水中2,4-D的间接竞争 ELISA检测方法．本研究比较了包被抗原2,4-D-BSA浓度分别为240ng·mL-1、120ng·mL-1和60ng·mL-1的反应体系和竞争反应时间为60min和15min的间接竞争ELISA剂量-反应曲线,确定了当包被抗原浓度为60 ng·mL-1、竞争反应时间为15min时,剂量-反应曲线的IC50值较低．采用上述实验条件分别测定了由PBS缓冲溶液、饮用水、清华大学地下水和圆明园福海地表水配制的2,4-D标准溶液的剂量．反应曲线,发现实际水样的基质效应对检测结果的影响较大;采用实际水样和PBS缓冲溶液配水在含有5％乙醇的PBS缓冲体系中反应的方法,基本上消除了基质效应对检测结果的干扰．采用上述优化试验条件,测定2,4-D浓度分别为0．5mg·L-1、0．125mg·L-1和0．03mg·L-1的加标样品,测定数据的准确度符合痕量有机污染物定量检测对准确度的要求,但是平行样品测定数据之间的变异系数较大,需要进一步改进检测方法,用于实际水样的检测．

2-(2-喹啉偶氮)-4-甲基-1,3-二羟基苯固相萃取光度法测定水中锌

研究了试剂2-（2-喹啉偶氮）-4-甲基-1，3-二羟基苯（QAMDHB）与锌的显色反应，在pH 8．5的硼酸-氢氧化钠缓冲介质中，TritonX-100存在下，QAMDHB与锌反应生成2：1稳定络合物，体系最大吸收波长λmax=565 nm，表观摩尔吸光系数ω=8．84×10^4 L·moL^-1·cm^-1。样品中的锌用强阴离子交换固相萃取柱固相萃取预分离富集后。用6 mL水反向洗脱，分光光度法测定。方法线性范围为0．01～1．0／μg／mL。用于实际水样测定，RSD为2．2％，2．4％，标准加入回收率为103％，97％，测定结果与原子吸收光谱法相符。

类Fenton试剂-罗丹明B-HCl体系动力学荧光法测定环境水样中2,4-二氯酚

在酸性介质中，痕量2，4-二氯酚对类Fenton试剂与罗丹明B的反应具有明显阻抑作用，且其阻抑作用大小与2，4-二氯酚的浓度有关。据此建立了一种动力学荧光法测定痕量2，4-二氯酚的新方法。考察了各种因素对测定方法灵敏度的影响。在最佳条件下，方法的线性范围为0．04～0．8 μg/mL，检出限为0．012 μg／mL。将该方法用于7种环境水样和6种合成样品中2，4-二氯酚的测定，加标回收率为93．5％～108．0％。相对误差为-5．45％～4．60％。

2-(5-硝基-4-甲基-2-吡啶偶氮)-5-二甲氨基苯胺激光热透镜光谱法测定钴的研究及其应用

在pH 4.0~7.0的HAc-NaAc缓冲介质中,并在50%乙醇存在下,Co(Ⅱ)与新试剂2-(5-硝基-4-甲基-2-吡啶偶氮)-5-二甲氨基苯胺(5-NO_3-4-CH_3-PADMA)反应形成紫红色配合物;钴配合物形成后,当以强酸酸化,提高酸度至1.8mol/L H_2SO_4介质,可转变为另一种具有较高吸收特性的绿蓝色质子化形体,最大吸收波长位于622nm处,与所用He-Ne激光器的输出激光波长(632.8nm)能较好匹配,据此建立了激光热透镜光谱法测定痕量钴的新方法。钴质量浓度在3~100ng/mL范围内与分析信号呈良好的线性关系,检出限为1.0ng/mL。常见金属离子不干扰钴的测定,特别是与钴伴生的铁、镍和铜等元素有较高的允许量,150倍量的Fe^(3+)和Ni^(2+)、5倍量的Cu^(2+)等不干扰钴的测定。实验方法应用于矿石中痕量钴的测定,结果与推荐值(原子吸收光谱法测定结果)一致,相对标准偏差在0.46%~1.46%之间。

高灵敏高选择性测镉新试剂——2-氯-4-硝基苯基重氮氨基偶氮苯的合成及应用

本文报道了高灵敏度高选择性测镉新试剂——2-氯-4-硝基苯基重氮氨基偶氮苯的合成、纯化及结构鉴定。研究了该试剂在不同表面活性剂存在下的酸性离解行为及其与镉(Ⅱ)的显色反应。实验结果表明,在Triton x-100存在下,于pH7.80的磷酸二氢钾-氢氧化钠缓冲介质中。镉(Ⅱ)可与该试剂形成稳定的红色配合物,其最大吸收波长位于505mm处,摩尔吸光系数为1.57×10~5L·mol^(-1)·cm^(-1)镉量在0～12μg/25mL范围内符合比尔定律。在所拟测定条件下,方法选择性甚佳,只有Ag^+、Hg^(2+)、Cu^(2+)离子产生干扰,可通过加入适当的掩蔽剂予以消除。方法可不经分离直接用于环境水样、工业废水及铝合金标样中痕量镉(Ⅱ)的测定,结果满意。

分散液液微萃取-高效液相色谱法测定环境水样中2,4-二氯酚

建立了简便、快速、有效的分散液液微萃取-高效液相色谱法测定环境水样中2,4-二氯酚的分析方法。对萃取剂、分散剂的种类和体积、萃取时间、离心时间、盐浓度等影响萃取效率的因素进行了优化。方法的线性范围为1～500μg/L(r=0.9997),相对标准偏差(RSD)为3.8%(n=6),检出限为0.19μg/L。该法适用于环境水样中的痕量2,4-二氯酚的检测。

Carbon Dots as“On–Off–On”Fluorescence Sensors for Selective and Consecutive Detection of 4-Nitrophenol and Cerium(IV)in Water Samples

An“on–off–on”fluorescence sensor was designed for rapidly and consecutively detecting 4-nitrophenol and cerium(IV)without the use of any labeling materials.The yellow carbon dots were synthesized by a simple one-step hydrothermal approach,and various techniques were applied to investigate the morphology,structure,and optical properties of the carbon dots.Under the optimal experimental conditions,4-nitrophenol rapidly quenched the fluorescence of carbon dots as a result of the inner filter eff ect(IFE).The fluorescence intensity of carbon dots was linear with the concentration of 4-nitrophenol(1–150μmol/L)and the limit of detection was 0.32μmol/L.The fluorescence was gradually recovered as the cerium(IV)concentration(0.5–100μmol/L)increased in CDs/4-NP,and the limit of detection was 0.16μmol/L.The sensor showed good selectivity and demonstrated high accuracy for the analysis of 4-nitrophenol and cerium(IV)in actual water samples.

高效液相色谱法测定豆芽中痕量2,4-二氯苯氧乙酸

以氯甲基化交联聚苯乙烯树脂（CMCPS）为载体和大分子引发剂,2,4-二氯苯氧乙酸（2,4-D）为模板,丙烯酰胺（AM）为单体,采用表面引发原子转移自由基聚合（SI-ATRP）技术,制备了2,4-二氯苯氧乙酸分子印迹聚合物（MIPs）,并将该聚合物作为固相萃取剂,以高效液相色谱法测定豆芽样品中的痕量2,4-D,加标回收率为86%~104%,相对标准偏差为1.9%~10%,检出限为20 ng/g。该印迹材料稳定性好,且有良好的再生性能。

4-(2-噻唑偶氮)连苯三酚分光光度法测定钢中微量钨

在稀硫酸介质及溴化十六烷基吡啶（CPB）存在下，试剂4-（2-噻唑偶氮）连苯三酚（TATB）与钨（Ⅵ）发生显色反应，据此建立了分光光度法测定钢样中微量钨的方法。研究发现：TATB与钨㈣形成2：1的红色络舍物，该络合物的最大吸收波长在530nm处。25mL溶液中，钨质量在0～40μg范围内服从比尔定律，测得表观摩尔吸光系数为6．16×10^4L·mol^-1·cm^-1。方法用于钢样中微量钨的测定，结果同硫氰酸盐光度法所得结果相吻合。