Coil tuning detection module design of magnetic resonance imaging

线圈作为磁共振成像系统的重要组成部分,其性能直接影响成像质量。为了尽可能保证信噪比和图像质量,探测前需进行线圈调谐。调谐时,通过微调线圈的共振频率和阻抗两个参数,使线圈共振频率与拉莫尔频率一致,线圈和前放电路阻抗匹配。本文设计了一种线圈调谐的检测模块,阐述了模块的工作原理和软硬件设计。模块包括测量、处理两个部分,其中采用STM32采集电压数据,通过数据转换后用液晶屏显示实时波形。实际结果表明,此检测模块不仅延续了上位机调谐显示直观清晰的优点,而且兼具独立数码显示表的操作便捷的优点。Coil as an important part of magnetic resonance imaging system,its performance directly effects the imaging quality.In order to ensure the signal-to-noise and image quality as much as possible,it must tune before detect.When tuning,it make the coil resonance frequency is consistent whit the larmor frequency,coil and the circuit impedance matching by tuning the coli frequency and impedance.In this paper,we design a coil tuning detection module,elaborated the principle of module and design of software and hardware.This module includes two parts:measurement and processing. Use STM32 to collect the data of voltage,and display real-time waveform by LCD screen.It turned out that this module not only has the advantage of intuitive and clear by upper machine tuning,and both has the advantage of convenient operation.国家自然科学基金(11175149)资助项

Synthesis and characterization of cellulose acetate with high degree of substitution from miscanthus

以芒草为原料,用Na OH/H_2O_2溶液体系预处理制备芒草纤维,在冰醋酸环境下,以浓硫酸为催化剂与醋酸酐酯化制备芒草醋酸纤维素。优化了预处理条件:温度、时间、次数和酯化条件:催化剂量、温度、时间、醋酸酐量,最佳条件下制备出的芒草纤维的纤维素、半纤维素和木质素的质量分数分别为75.3%、17.3%、5.1%,制备出芒草醋酸纤维素的取代度DS=2.8,特性黏度[η]=1.24 d L/g,达到美国联邦贸易委员会指南认定的三醋酸纤维素标准。利用扫描电镜(SEM)和热分析(TG、DSC)对制得样品进行表征。结果表明,可以利用Na OH/H_2O_2水溶液体系预处理芒草原料制备芒草纤维,并进一步酯化制备出高取代度的醋酸纤维素。A procedure for synthesizing cellulose acetate with high degree of substitution from miscanthus biomass is developed. The miscanthus fiber is prepared by pretreatment of miscanthus biomass with Na OH / H_2O_2,which is then reacted with acetic anhydride in an acetic acid solvent to synthesize cellulose acetate by using concentrated sulfuric acid as catalyst. The effects of the pretreatment factors( such as pretreatment temperature,time and number of times) and the esterification factors( such as catalyst volume,reaction temperature,reaction time and acetic anhydride volume) are studied. Under the optimal conditions,the contents of cellulose,hemicellulose and lignin for prepared miscanthus fiber are75. 3%,17. 3% and 5. 1%,respectively. The degree of substitution( DS) and the intrinsic viscosity( [η ]) of the obtained miscanthus cellulose acetate are 2. 8 and 1. 24 d L / g,respectively. The miscanthus biomass,fiber and cellulose acetate are characterized by SEM,TG and DSC. This study shows that cellulose acetate with high degree of substitution can be prepared from miscanthus biomass pretreated with Na OH / H_2O_2.国家自然科学基金(21303142;31170067);; 福建省中青年教师教育科研项目(JA14010);; 厦门市海洋经济发展专项资金项目(14GZP59HJ29);; 福建省海洋高新产业发展专项项目(闽海洋高新[2014]25号);; 厦门大学校长基金(20720150090

Cloning and Sequence Analysis of Cellulase Genes from Hypocrea orientalis EU7-22

作者简介: 龙传南, 男, 博士研究生, 研究方向: 生物能源; E-mail: [email protected] 通讯作者: 龙敏南, 男, 教授, 研究方向: 生物质资源利用; E-mail: [email protected][中文文摘]东方肉座菌EU7-22与XC-9、里氏木霉、康宁木霉、黑曲霉、斜卧青霉进行产纤维素酶比较,结果表明菌株EU7-22具有较高的产纤维素酶能力及完整的纤维素酶系。根据里氏木霉和绿色木霉的外切葡聚糖酶,内切葡聚糖酶及β-葡萄糖苷酶相关基因序列,设计引物PCR扩增出菌株EU7-22 cbhⅠ、cbhⅡ、egⅠ、egⅡ及bglⅠ。基因序列经NCBI Blast分析表明,cbhⅠ与绿色木霉cbh1基因(FJ871063)同源性最高达99%;cbhⅡ与康宁木霉cbh2基因(DQ504304)同源性最高达99%;egⅠ与长枝木霉eg1基因(GU144298)同源性最高达99%;egⅡ与绿色木霉eg2基因(EF602036)同源性最高达99%;bglⅠ与菌株Trichodermasp.SSLbgl基因(FJ040193)同源性最高达100%。5种纤维素酶基因编码的相应氨基酸序列与其他木霉纤维素酶的氨基酸序列相似性也非常高。对上述纤维素酶基因编码的相应蛋白的分子量、等电点、N-糖基化位点、信号肽序列进行分析;对纤维素结合区及糖基水解酶家族特征结构区进行了定位;用SWISS-Model模拟了酶蛋白的三级结构。[英文文摘]The fungi of Hypocrea orientalis EU7-22, Hypocrea orientalis XC-9, Trichoderma reesei, Trichoderma koningii, Aspergillus niger and Penicillium decumbens were investigated to produce cellulase. The results indicated that the strain EU7-22 had highly cellulase activities in comparison with other fungi, and possessed of integrated cellulase system. According to the reported cellobiohydrolase, endoglucanase and β-glucosidase gene sequences of T. reesei and Trichoderma viride, the primers were designed and five cellulase genes（cbhⅠ, cbhⅡ, egⅠ, egⅡ, bgl Ⅰ）were successfully cloned by PCR. By conducting sequence alignment analysis with NCBI Blast, it was found that the homology of same cellulase genes between strain EU7-22 and other Trichoderma were: 99% to cbh1（FJ871063）from T. viride；99% to cbh2（DQ504304）from T. koninqii ；99% to eg1（GU144298）from Trichoderma longibrachiatum ；99% to eg2（EF602036）from T. viride ；100% to bgl（FJ040193）from Trichoderma sp. SSL. Furthermore, the corresponding amino acid sequences were also quite similar. The molecular weight, isoelectric point, N-glycosylation sites and signal peptide sequence of these cellulase genes encoding the corresponding protein were analyzed. The cellulosebinding domain and conserved domains of glycosyl hydrolases family were confirmed. By using SWISS-Model, the tertiary structure of cellulase proteins were predicted and simulated.国家重点基础研究发展计划(“973”计划)(2010CB732201);中央高校基本科研业务费专项资金项目(201112G026);国家自然科学基金项目(31170067

Heterologous Expression of the β-Glucosidase and Its Synergistic Hydrolysis of Bamboo with Cellulase

在毕赤酵母gS115中表达东方肉座菌Eu7-22的β-葡萄糖苷酶基因(bgl),获得基因工程菌株bP17。优化bP17収酵产酶条件后,重组β-葡萄糖苷酶活力达121 Iu/Ml。酶学性质研究表明,该酶最适反应温度为70℃,在60℃以下有较好的热稳定性;最适催化PH为5.0,在PH 3.0~8.0之间有较好的稳定性。将异源表达的β-葡萄糖苷酶添加到东方肉座菌的纤维素酶液中协同降解经过预处理的竹纤维,当纤维素酶添加量为fPA 20 Iu/g底物,β-葡萄糖苷酶添加量为bg 6 Iu/g底物时,纤维二糖浓度显著下降,酶解得率达到83.03%,表明重组β-葡萄糖苷酶的加入更有利于纤维素的酶解糖化。The β-glucosidase gene(bglI) from Hypocrea orientalis EU7-22 was cloned and effectively expressed in Pichia pastoris GS115.The-glucosidase activity expressed by recombinant strain BP17 reached 121 IU/mL.The expressed-glucosidase exhibited the optimum catalytic activity at 70°C and pH 5.0.The enzyme exhibited good stability at pH 3.0 ~ 8.0 and remained 65% of its original activity after 1 h at 60°C.The pretreated bamboo cellulose was synergistic hydrolyzed by the cellulases from Hypocrea orientalis EU7-22 and the recombinant β-glucosidase from strain BP17.Supplementing recombinant β-glucosidase greatly reduced the inhibitory effect caused by cellobiose, and the hydrolysis yield was improved to 83.03% with enhanced β-glucosidase activity of 6 IU/g substrate.The results indicated the recombinant β-glucosidase significantly boost the efficiency of saccharification.国家重点基础研究发展计划(2010CB732201); 国家自然科学基金(31170067); 中央高校基本科研业务费专项资金(201112G026

HPLC and MALDI-Tof-MS Analysis of Hydrolysates of Xylan

利用HPlC结合MAldI-TOf-MS对1-苯基-3-甲基-5-吡唑啉酮(PMP)衍生化后山毛榉木聚糖水解产物进行分析,检测到了难以获得标准品对照的木聚糖水解产物。结果表明,稀硫酸水解山毛榉木聚糖的主要水解产物有木糖和4-O-甲基葡萄糖醛酸-木糖(b2),以及少量4-O-甲基葡萄糖醛酸(b1)。内切重组木聚糖酶An Xyn10C水解山毛榉木聚糖产生木糖、木二糖和4-O-甲基葡萄糖醛酸-木三糖(b3),而内切重组木聚糖酶HO Xyn11A水解山毛榉木聚糖主要产生木糖、木二糖、木三糖、4-O-甲基葡萄糖醛酸-木四糖(b4)和4-O-甲基葡萄糖醛酸-木五糖(b5)。基于PMP柱前衍生化的HPlC结合MAldI-TOf-MS方法能高效地分析复杂的木聚糖水解产物。The hydrolysis end products of beechwood xylan,which were released by sulfuric acid or enzymes and then labeled at their reducing ends with 1-phenyl-3-methyl-5-pyrazolone( PMP) derivatization,were analyzed by HPLC assisted with MALDITof-MS.Some of the hydrolysates,which were lack of related commercial available standard substances,were determined.It was found that the xylose and 4-O-methyl-glucuronic acid-xylose( B2) were the main products with minor amounts of 4-Omethylglucuronic acid( B1) in the hydrolysates of beechwood xylan by sulfuric acid.Recombinant endo-β-1,4-xylanase An Xyn10 C released xylose,xylobiose,and 4-O-methyl-glucuronic acid-xylotriose( B3) as the main hydrolysates from beechwood xylan,whereas recombinant endo-β-1,4-xylanase Ho Xyn11 A released xylose,xylobiose,xylotriose,4-O-methyl-glucuronic acidxylotetrose( B4) and-xylopentaose( B5),and aldohexaouronic acid.These results revealed that HPLC assisted with MALDITof-MS based on PMP derivatization was a very useful and robust method for the determination of products in hydrolysis of xylan.国家自然科学基金资助项目(31170067); 厦门市海洋经济发展专项资金项目(14GZP59HJ29); 福建省海洋高新产业发展专项项目(闽海洋高新[2014]25号

7000m sea trials test of the deep manned submersible “JIAOLONG”

蛟龙号载人潜水器研制是国家863计划重大专项之一,其目标是建造出一台可以执行规定使命任务的产品。海上试验是载人潜水器重大专项的关键阶段,2009年8～10月、2010年5～7月和2011年7～8月,分别完成了1000米、3000米和5000米级的海上试验任务。文章主要介绍了在2012年6月3日～7月16日之间完成的7000米级海上试验,内容包括海上试验的基本情况、海试取得的主要技术和应用成果、海试过程中发现的故障及处理情况以及对今后投入应用的启示,最后给出7000米级海上试验的主要结论

沙坡头地区土壤水分吸湿凝结的动态观测与理论计算

采用实际观测与理论计算相结合方法研究了沙地表层土壤吸湿凝结水量及其变化过程。沙土水分吸湿凝结过程可分两个阶段：第一阶段是由沙土自身物理性质决定的分子凝结过程，所吸收水量主要受温度和湿度影响，最大不超过沙土最大吸湿水量；第二阶段是由近地面微气象条件决定的水分凝结过程，所吸收水量受空气水汽压、地面温度和地表可利用能量的影响。采用能量平衡和空气动力学综合方法计算沙地吸湿凝水量及其动态变化，与实测值相比结果合理，方法是可行的。The process and amounts of moisture absorption and water condensation in the surface shallow layer of sandy soil are studied preliminarily by the method combining field measurement with theoretical calculation. The results showed that the formation process of water absorption and condensation in sandy soil is composed of two stages. The first one is the process of water molecular absorption determined by the physical properties of sandy soil. The amounts of water absorbed is affected by temperature and humi...国家自然科学基

基于连续变量真空噪声量子随机数的高速产生

针对当前量子随机数产生技术无法满足通信领域中安全性和高速率的问题,文章提出了一种基于测量光场真空起伏产生量子真随机数的实验方案。与以往报道的实验方案所不同,文章理论分析,量子随机数生成系统中量子正交分量测量中本底光增益对原始随机数中相对量子熵含量的影响,在经典噪声完全被窃听方控制的最差情况假定下,采用量子条件最小熵量化评估原始随机数的随机性。基于理论分析实验中通过相对增强本底光强的同时控制电子学增益,经典电子噪声独立地放大真空噪声分量起伏,提高了系统中量子噪声引入的最小熵含量,同时,基于真空量子噪声是宽带高斯白噪声,有效提升频带提取带宽,提高量子熵源的利用率,在提高量子随机数生成系统安全性的同时提高了量子随机数的产生速率。实验结果表明,基于安全性信息论可证明的托普利茨-哈希（Toeplitz-hash）提取器,实现了6.7 Gbit/s的量子随机数产生,同时利用Nist、Diehard和TestU01-SmallCrush 3种随机数标准测试验证了该方案下生成的量子随机数的真随机性,为真空量子随机数发生器产生速率的提高提供了新的途径

施氮和供水对混播和单播白羊草叶片 叶绿素荧光特性的影响

为明确干旱条件下混播和施氮对白羊草〔Bothriochloa ischaemum ( Linn．) Keng〕叶片叶绿素荧光参数的影响， 采用盆栽法并设置不同混播比例〔白羊草与柳枝稷( Panicum virgatum Linn．) 混播比例分别为8 ∶0、6 ∶2、4 ∶4和2 ∶6〕、 施氮水平( 即不施氮和1 kg 干土施0. 1 g 纯氮) 和供水条件( 即正常供水和干旱胁迫6 d 后复水) ，对白羊草叶片叶 绿素荧光参数的变化进行比较分析; 在此基础上，采用一般线性模型分析这3 个因素及其交互作用对白羊草叶绿 素荧光参数的影响效应。结果显示: 正常供水条件下，各处理组白羊草的最大光化学效率( Fv /Fm ) 、实际光化学效 率( &Phi;PSⅡ ) 、表观光合电子传递速率( ETＲ) 、光化学淬灭系数( qP) 和非光化学淬灭系数( NPQ) 均无明显变化。干旱 及复水条件下，不施氮处理组白羊草的Fv /Fm 值在干旱胁迫6 d( 即土壤相对含水量最低) 时降至最低值，并在复水 2 d后恢复至与正常供水条件下相近的水平，而施氮处理组的Fv /Fm 值则一直保持与正常供水条件下相近的水平; 不论施氮与否，各处理组白羊草的&Phi;PSⅡ、ETＲ、qP 和NPQ 值基本上均表现为在干旱胁迫6 d 时达到最高值，并在复 水2 d 后恢复至正常供水条件下各参数值的90%以上。总体上看，混播白羊草的qP 和ETＲ 值均高于单播白羊草， 而其NPQ 值则低于后者。统计分析结果表明: 混播比例、施氮水平和供水条件3 个因素间的交互作用对白羊草的 &Phi;PSⅡ、qP 和ETＲ 值无显著影响，施氮水平对NPQ 值的单独作用、施氮水平和混播比例的交互作用对Fv /Fm 值以及 施氮水平和供水条件的交互作用对ETＲ 值也无显著影响，但这3 个因素的单独作用及两两因素间的交互作用对白 羊草其余叶绿素荧光参数均有显著或极显著影响。研究结果表明: 一定程度的干旱胁迫有利于提高白羊草叶片 PSⅡ反应中心的开放程度、光合电子传递速率和热耗散过剩光能的能力; 在干旱胁迫条件下，施氮有助于白羊草叶 片维持PSⅡ反应中心的活性和光化学效率; 并且，与柳枝稷适度混播可改善白羊草叶片的光合性能，提高其种间竞 争适应性。</p