透镜到样品表面距离对LIBS测量的影响

采用Nd:YAG激光器产生的脉冲激光诱导击穿铜片形成等离子体,研究了透镜到样品表面距离的不同对激光诱导击穿光谱(LIBS)测量的影响.实验选择合适的延迟时间和采样门宽,并选用元素谱线λ(Cu)为324.8 nm和327.4 nm,λ(Zn)为330.3 nm和334.5 nm进行分析.实验结果表明,透镜到样品表面的距离对LIBS测量确实有很大的影响,谱线强度以及其相对标准偏差均与透镜到样品表面距离密切相关.透镜到样品表面的距离大于焦距时,空气击穿现象严重,不宜用于LIBS测量.激光脉冲能量大,透镜到样品表面距离对LIBS测量的影响大,激光脉冲能量小则相反.     

热棒在混凝土温控中应用的试验研究

热棒作为一种有效的传热元件,主要用来解决多年冻土区域的地基冷却问题,其在混凝土温控中的应用较少.分别进行无热棒和使用不同规格热棒进行温控的混凝土温升试验,通过试验对比分析来研究热棒在混凝土温控中的应用.试验结果表明:热棒可以有效将混凝土的水化热传递至大气中,使混凝土峰值温度大幅降低,峰值时间提前,并且缩短最终到达稳定温度的时间.     

A novel photoluminescent and photochromic europium complex

A ternary europium complex of 4-aminobutyric acid (ABA) with 1,10-phenanthroline (phen) [Eu₂(ABA)₄ (phen)₄](phen)₄(ClO₄)₆ was synthesized and characterized by X-ray single crystal diffraction. The result shows that 4-aminobutyric acid exists in zwitterion form in the binuclear complex and that the carboxylates coordinate with Eu³⁺ ion in bidentate bridging and tridentate chelating-bridging modes. There are two types of phen molecules, one is coordinated and the other is uncoordinated. When excited by YAG︰Nd laser with 355 nm light, the title complex can emit strong red fluorescence, and its high-resolution emission spectrum was recorded at 77 K. The Eu³⁺ ion site is in low symmetry, which is in agreement with the result of X-ray single crystal diffraction analysis. When irradiated with a mercury lamp, the aqueous solution of the title complex can perform photochromism with the color change from colorless to green and the green color can fade away in the dark. The photochromic response time is related to the concentration and pH of the solution, the temperature and the light intensity.     

LSP1抑制万珂诱导的多发性骨髓瘤细胞凋亡(英文)

淋巴细胞特异性蛋白-1(LSP1)在部分多发性骨髓瘤中表达升高,但其在肿瘤中的作用仍知之甚少.研究了LSP1在多发性骨髓瘤中抗新型抗肿瘤药物万珂(Bortezomib)诱导细胞凋亡的作用及机制.筛选LSP1高表达和低表达的多发性骨髓瘤细胞IM9和KAS6作为实验模型.应用RNA干扰基因沉默IM9细胞中的LSP1,或在KAS6细胞中转染LSP1表达质粒,用Bortezomib等化疗药物处理细胞后,PI/Annexin V染色并用流式细胞仪检测和分析细胞凋亡率.同时RT-PCR方法检测和分析被LSP1所影响的重要细胞凋亡相关基因的变化.结果发现,LSP1在多发性骨髓瘤细胞IM9和KAS6中差异性表达高和低,与Bortezomib诱导的细胞凋亡效率密切相关.利用RNA干扰敲低IM9细胞中LSP1,可显著增强IM9对Bortezomib的敏感性,同时在KAS6中转染LSP1表达质粒,可降低Bortezomib诱导的细胞凋亡.对部分重要凋亡基因的RT-PCR检测发现,LSP1可诱导BCL-xl基因表达,同时抑制p53表达.因此,发现LSP1可通过调节凋亡基因的表达促进肿瘤的抗药性.     

钢筋混凝土双向板肋梁楼盖可靠度分析

讨论钢筋混凝土双向板肋梁楼盖可靠度分析，以塑性理论为基础确定双向板及其支承梁的主要失效机构，采用一肌界限法和概率网络估算计算法该结构体系的可靠度，根据可靠度计算结果，提出了几点建议。     

Role of the prolyl isomerase Pin1 in protecting against age-dependent neurodegeneration

The neuropathological hallmarks of Alzheimer's disease and other tauopathies include senile plaques and/or neurofibrillary tangles. Although mouse models have been created by overexpressing specific proteins including beta-amyloid precursor protein, presenilin and tau, no model has been generated by gene knockout. Phosphorylation of tau and other proteins on serine or threonine residues preceding proline seems to precede tangle formation and neurodegeneration in Alzheimer's disease. Notably, these phospho(Ser/Thr)-Pro motifs exist in two distinct conformations, whose conversion in some proteins is catalysed by the Pin1 prolyl isomerase. Pin1 activity can directly restore the conformation and function of phosphorylated tau or it can do so indirectly by promoting its dephosphorylation, which suggests that Pin1 is involved in neurodegeneration; however, genetic evidence is lacking. Here we show that Pin1 expression is inversely correlated with predicted neuronal vulnerability and actual neurofibrillary degeneration in Alzheimer's disease. Pin1 knockout in mice causes progressive age-dependent neuropathy characterized by motor and behavioural deficits, tau hyperphosphorylation, tau filament formation and neuronal degeneration. Thus, Pin1 is pivotal in protecting against age-dependent neurodegeneration, providing insight into the pathogenesis and treatment of Alzheimer's disease and other tauopathies.     

多梁结构压阻式测振加速度传感器

为满足制造装备智能化发展对测振传感器的需求,针对常见加速度传感器在性能、成本和微型化上的不足,研制了一种基于微机电系统技术的多梁结构压阻式加速度传感器.通过将2根短小敏感梁引入传统双桥结构的方式,在提升固有频率的同时,保证了传感器仍具有较高的测量灵敏度.利用敏感梁上的最大应力和结构固有频率相乘的结果作为性能评价标准,结合梁变形理论和实际工艺条件确定了传感器的结构尺寸.采用硅材料刻蚀、硼离子注入、溅射金属铝及阳极键合等工艺,制作了传感器芯片.实验结果表明,所研制的加速度传感器能够准确测量不同频率下的加速度信号,在每g下的灵敏度达到了0.544 mV,满量程精度达到了1.76％,固有频率达到了13.61 kHz,相对于双桥结构传感器,其综合性能提升了近85％.     

运用HSV－tk／ACV系统进行肿瘤基因治疗研究

构建了含ｐｇｋ启动子驱动的ＨＳＶ－ｔｋ基因的反转录病毒载体ｐＬＮＴＫ，将ＨＳＶ－ｔｋ基因转移至人脑胶质瘤ＳＨＧ４４细胞（命名为ＳＨＧＬＮＴＫ）及小鼠黑色素瘤细胞Ｂ１６（命名为Ｂ１６ＬＮＴＫ）．体外实验证实核着类似物ＡＣＶ对ＳＨＧＬＮＴＫ细胞和Ｂ１６ＬＮＴＫ细胞的杀伤敏感性分别高于亲本细胞１０００和４００倍．转ＨＳＶ－ｔｋ基因细胞与亲本细胞按不同比例共培养时，亲本细胞对ＡＣＶ的敏感性明显增高，存在旁观者效应．首次应用人脑胶质瘤细胞株进行裸鼠体内实验，结果表明：ＡＣＶ能完全抑制ＳＨＧＬＮＴＫ细胞在裸小鼠体内肿瘤的形成，对裸小鼠体内已形成的ＳＨＧＬＮＴＫ肿瘤的治疗效果与对照ＳＨＧ４４肿瘤相比，肿瘤体积缩小８０％；用Ｂ１６ＬＮＴＫ细胞接种同系Ｃ５７／ＢＬ小鼠，经ＡＣＶ治疗后，Ｂ１６ＬＮＴＫ组小鼠的肿瘤较对照组Ｂ１６肿瘤小９５％．ＨＳＶ－ＴＫ／ＡＣＶ系统原位基因转移治疗ＳＨＧ荷瘤裸小鼠、Ｂ１６荷瘤小鼠，原位注射病毒悬液／ＡＣＶ治疗组的ＳＨＧ肿瘤、Ｂ１６肿瘤分别较对照组肿瘤小５０％，４３％，原位注射ＰＡ３１７／ＬＮＴＫ细胞，ＡＣＶ治疗的ＳＨＧ肿瘤较对照组肿瘤小９０％，以上实验结果，统计学上差异极显著，Ｐ＜０．０１．实验     

面向对象建模方法研究

本文首先介绍了面向对象建模方法的发展近况,然后就几种主要的面向对象建模方法进行了比较和分析,最后简单阐述了这一领域今后的发展趋势。     

浅谈网络环境下高校图书馆的信息服务与创新

阐述了网络环境下高校图书馆信息服务的新内容,指出网络环境对高校图书馆信息服务的要求。