生物絮凝剂产生菌的N+注入诱变选育及其培养条件研究

为获得高絮凝活性菌株,采用低能氮离子诱变方法,对生物絮凝剂产生菌FJ-7进行诱变选育,筛选得到一株絮凝活性高、遗传稳定性良好的突变株NIM-192.发酵产絮凝剂曲线表明,其菌体生长速度稍慢于原始菌株,但絮凝活性一直高于原始菌株,絮凝率比原始菌株提高了34.26%.进一步研究表明,蔗糖、葡萄糖、半乳糖是NIM-192产生絮凝剂的适宜碳源,酵母膏:尿素为1:1的混合氮源为最佳氮源,培养基起始pH为7～9时,发酵液的絮凝效果最好.     

从环丝氨酸抗性突变株中筛选α－淀粉酶高产菌株

以枯草杆菌ＢＦ－７６５８发出了菌株，采用化学诱变剂甲基磺酸乙酯（ＥＭＳ）诱变，筛选Ｄ－环丝氨酸抗性株，逐步增加环丝氨酸浓度，从中得到α－淀粉酶高产菌株ＮＨ－５。采用往复式摇床和２Ｌ玻璃发酵罐进行发酵试验，ＮＨ－５菌株酶活较出发菌分别提高３０％和４８％。     

利用假单胞菌天冬氨酸－β－脱羧酶高效生产L－丙氨酸

通过诱变筛选得到一株具有高活性Ｌ－Ａｓｐ－β－脱羧酶的菌株ＰｓｅｕｄｏｍｏｎａｓＮＸ－１，对该株酶形成和酶反应的条件进行了详细研究，该株可以高效地转化Ｌ－Ａｓｐ生成Ｌ－ＡＩａ，转化４～５山每Ｌ培养液可转化Ｌ－Ａｓｐ量高达１４００ｇ左右，生成Ｌ－Ａｌａ浓度高达９０％以上，摩尔转化率近１００％。     

产淀粉酶菌的筛选和诱变

淀粉酶在造纸工业中被广泛利用,淀粉酶的需求量越来越大,获得高产淀粉酶菌株是解决该问题的重要途径。采用透明圈法筛选获得 3 株产淀粉酶的细菌,并对它们进行紫外光和超声波诱变研究,探究其产淀粉酶的最佳诱变条件。实验结果显示,菌株紫外光诱变的适宜照射时间为 30 s,最佳照射距离为 15 cm,C1 菌和 S 菌的诱变效果较好,在此条件下的比透明圈都为 3.00。超声波诱变的适宜时间为 20 min,C1 菌和 S 菌的比透明圈都为 2.50。 研究表明,紫外光和超声波诱变都能提高产酶量,紫外光诱变的效果较超声 波诱变更稳定,超声波诱变后的产酶量低于紫外光诱变。     

大豆根瘤菌8－1－4A色氨酸营养缺陷突变型的筛选及其原养型回复突变株共生效率的研究

采用转座子Ｔｎ５诱变快生型大豆根瘤菌（Ｒｈｉｚｏｂｉｕｍｆｒｅｄｉｉ）８－１－４Ａ筛选到１０个色氨酸营养缺陷型突变株，植物结瘤试验表明这些菌均失去了结瘤能力。经自发突变，从培养平板和振瘤中分离出２３个色氨酸原养回复突变株，盆栽试验结果表明有２２株的结瘤能力得到恢复，其中有５株的共生效率与出发菌相比有显著提高。对部分回复突变株进行了质粒检测和以标记Ｔｎ５为探针的ＳｏｕｔｈｅｒｎＤＮＡ杂交分析。     

激光晶体YAG中E_r~（3＋）离子最佳掺杂浓度

测试了２ａｔ．％Ｅｒ：ＹＡＧ晶体的吸收谱，荧光谱，４Ｉ１１／２、４Ｉ１３／２态荧光衰减曲线．由荧光衰减曲线拟合得到荧光寿命τ０和描述离子间的相互作用微参量ＣＤＡ，并将其代入作者推导得到的最佳掺杂浓度的近似式，计算出Ｅｒ３＋离子在ＹＡＧ晶体中的最佳掺杂浓度，并与实验结果进行了比较     

抗菌核病转基因油菜植株的获得

将携带菜豆几丁质酶基因的植物表达载体ｐＢｃｈ通过农秆菌介导法导入甘兰型油菜Ｈ１６５中。经卡那霉素对Ｔ０、Ｔ１和Ｔ２代植株进行连续的筛选和菌核病（ｓｃｌｅｒｏ－ｔｉｎｉａ ｓｃｌｅｒｏｔｉｎｏｒｉｕｍ）接种试验,共获得２２株抗菌核病的Ｔ２代植株。对其中的２２株进行ＰＣＲＳ检测,从６株扩增得到与菜豆几丁质酶基因大小对应的ＤＮＡ带型,Ｓｏｕｔｈｅｒｎ杂交证实其中２株呈现阳性结果,表明外源基因已整合到油菜     

低温脂肪酶产生菌的筛选、鉴定及其部分酶学性质

从南极乔治王岛冻土来源的76株低温细菌中筛选到13株低温脂肪酶产生菌，对其中的BTsl0022菌株进行鉴定。通过生理生化特征、16s rDNA基因序列的同源性和系统发育分析发现，菌株RTsl0022属于假单胞菌属(Pseudomonas)，但与已定名的假单胞菌有一定的差异，与未定名的Pseudomonas sp．PsB的亲缘关系最接近，故将其暂定名为Pseudomonas sp．BTsl0022。对该菌脂肪酶的酶学性质初步研究表明，酶的最适作用温度为24℃，对热敏感，60℃处理30min仅残留25％酶活性，酶的适宜作用pH范围在7．0～9．0，最适pH为8．0。     

相关免疫布尔函数的一种构造方法

本文证明了布尔函数的谱分解定理，定义了布尔函数的谱（分解）特征向量，给出相应的充要条件，将全部Ｎ元相关免疫布尔函数的构造问题转化为线性方程组的求解问题，为相关免疫布尔函数的构造提供了新的方法。）满足，可求得符合要求的用上述方法我们通过人工计算确定出８６个符合要求的谱特征向量，注意到向量中各分量地位的对称性，并注意到定理４，我们得知全部４无相关免疫的非平凡布尔函数共２×３２４＝６４８个Ｎ＝４，ｍ＝２时，定理６中条件即从后面１１个方程可求得联系（Ⅱ）中的第５～１４个方和即知在（Ⅲ４）下ｂ１、ｂ２、ｂ３、ｂ４全为１（全为０平凡情况），在（Ⅲ４）下ｂ１、ｂ２、ｂ３、ｂ４中有３个取１、１个取０，由此可得全部４元至少２阶相关免疫的非平凡布尔函数所对应的谱特征向量如下：它们所对应的的布尔函数依次是（此结论与［１］ｐ１５５上结论相符），因而４元１阶相关免疫的布尔函数共有６４８－１０＝６３８个。一般情况下，在我们的方法里构造全部Ｎ元相关免疫布尔函数实质上是在定理６中“约束条件”（１）下去求２Ｎ－１个变元、Ｎ个方程的方程组（Ⅱ）所有解，构造全部Ｎ元至少ｍ（≥２）附相关免疫布尔函数实质上是在定理６中“约束条件，（１）下去解２Ｎ－     

氯代芳香族污染物生物降解菌株的分离及其降解质粒的初步研究

从工业废水污染的水体和污泥中,分离并筛选到６株对氯苯和苯酚类有机污染物高浓度耐受力的细菌菌株。６株降解细菌能在氯代苯和氯代酚作为唯一碳源的培养介质中生长,具有不同程度降解这类有机污染物的代谢能力,除２号和５号菌外,所筛选的其它４株降解细菌均含有一个或多个质粒。采用２,４－Ｄ单加氧酶基因ｔｆｄＡ的保守引物和ＰＣＲ扩增技术,证明在２号和６力的染色体和３号菌的大质粒上含有ｔｆｄＡ基因的同源序列。     

Urease producing microorganisms for coal dust suppression isolated from coal: Characterization and comparative study

In order to promote the biomineralization technology application to the field of coal dust inhibition, two strains of urease producing bacteria from coal were screened in this study. They are X3 with extracellular enzyme and X4 with intracellular enzyme. The ITS and 16S rDNA sequencing showed that the strains X3 and X4 were highly similar to Aspergillus sydowii and Bacillus DB-6. Strains X3 and X4 had their maximum urease activity at the initial 0.5 M urea concentration and slightly alkaline (pH 8) and neutral (pH 7) initial pH, respectively. Their mineralized products have a spherical structure and conform to the elemental composition of calcium carbonate. The dust suppression effect showed that both X3 and X4 bacteria liquid can effectively bind coal dust to form coal dust consolidation bodies containing calcite and vaterite type calcium carbonate. Interestingly, the coal dust consolidation body treated with the strain X4 is more resistant to wind and rain. The screening, mineralization and dust suppression potential analysis of the two strains of urease bacteria provided empirical support for the application of microbial induced calcium carbonate precipitation technology in the coal dust suppression.     

高速切削淬硬钢切屑变质层微结构及形成机理

为了揭示高速切削过程中切屑形成以及刀具-切屑界面摩擦机理,对剪切区内剪切带及白层进行了微观观察和分析.利用光学显微镜,SEM,电子探针,TEM和X射线衍射等方法对高速切削淬硬钢锯齿状切屑剪切变形区内变质层的微细组织进行了观察,对变质层的微结构本质及其形成机理进行了分析.研究表明:在锯齿状切屑锯齿之间的第一变形区存在绝热剪切带,由切屑基体到剪切带中心依次出现马氏体板条、沿剪切方向拉长并被位错分割的板条和等轴晶粒等不同的微结构特征;在切屑底部的第二变形区存在白层,其微结构显示了非晶组织特征.剪切带形成过程中没有相变发生,其形成是基于一种旋转式动态再结晶机制,白层的形成过程中发生了非晶转变和马氏体相变,形成机理属于相变机制.     

Effect of processing parameters on shear bands in non-isothermal hot forging of Ti -6Al -4V

Abstract

The alloy system Ti- 6Al- 4V is the prominent Ti alloy system for aerospace and biomedical applications, as a result of its mechanical property balance and biocompatibility. Since the mechanical characterisation of Ti- 6Al- 4V is strongly sensitive to processing parameters there is relationship between processing variables, i.e. strain rate and temperature, microstructure, and properties under different loading conditions. Two phase (α + β) titanium alloys undergo flow instabilities and are susceptible to shear bands or regions of localised deformation crossing many grains during hot forging under non-isothermal conditions (dies and workpiece at different temperatures). Under such conditions shear bands can be generated even in materials without flow softening attributes. This occurs if the forging parameters lead to large amounts of heat transfer between the dies and the workpiece. This study investigates the occurrence of shear bands during non-isothermal, hot forging of Ti -6Al- 4V in order to evaluate the process parameters that generally lead to shear bands in conventional hot forging of metals. Upset compression tests on cylindrical specimens were conducted in a mechanical press and lateral side pressing tests on long, round bars were performed in either a mechanical press or a hydraulic press. The tests ranged from axisymmetric to plane strain compression. In upset specimens shear bands occurred at an angle of 45° to the compression axis and bands of intense deformation separated chill zones from the deforming bulk. Observation also demonstrated that the fracture might be owing to microvoids nucleated at weak points in sections of the shear surfaces. For plane strain deformation, shear bands were found to initiate along zero extension directions in a manner analogous to the formation and propagation of shear bands in isothermal hot forging. Although the shear band features at hot forging temperatures were similar to each other, there was a difference in the hardness and thickness of the shear bands depending on deformation mode, amount, and temperature.     

基于局部位移场最小二乘拟合数字图像相关方法的剪切带应变测量

采用局部位移场最小二乘拟合数字图像相关方法测量了虚拟剪切带的应变,并将测量结果与中心差分方法的结果和理论解进行了对比,主要研究了计算窗口尺寸和子区尺寸的影响。研究发现:当子区尺寸较小且应变计算窗口尺寸较大时,局部位移场最小二乘拟合数字图像相关方法的测量结果接近于理论解;对于测量单轴压缩条件下低液限黏土试样破坏过程中的应变场,局部位移场最小二乘拟合方法的测量结果比中心差分方法测量结果更准确,有助于对剪切带应变的准确测量。     

Development of shear bands in dynamic plane strain compression of depleted uranium and tungsten blocks

We study the initiation and growth of shear bands in prismatic bodies of rectangular cross-section made of either depleted uranium or tungsten and deformed in plane strain compression at a nominal strain-rate of 5000 s⁻¹. It is assumed that defects are distributed symmetrically with respect to the two centroidal axes and each quadrant has up to 300 randomly distributed defects in the form of a weaker material; the flow stress for the weaker material in a quasistatic simple compression test is taken to be 5% lower than that for the original material. It is found that, in the deformed configuration, shear bands in depleted uranium blocks are inclined at approximately 42.5° counterclockwise from the horizontal axis, those in tungsten are inclined at nearly 135°. When shear bands initiate, the total compressive force required to deform the body drops sharply for the uranium blocks but gradually for the tungsten blocks. After a shear band has developed, dead zones form in both uranium and tungsten blocks; the size of the dead zone in the tungsten block is more than that in the uranium block. When the shear modulus for the tungsten is artificially changed so as to equal that for the uranium, the angle of inclination for the shear bands in tungsten blocks changes to that found for the uranium blocks. This suggests that the value of the shear modulus plays a noticeable role in the development of shear bands. We have also studied the effect, on the initiation of shear band, of modeling the defects as either very weak or very strong material.     

Effects of pores on shear bands in metallic glasses: A molecular dynamics study

The effects of nanoscale pores on the strength and ductility of porous Cu₄₆Zr₅₄ metallic glasses during nanoindentation and uniaxial compression tests are modelled and investigated using molecular dynamics (MD) simulations. In the MD simulations, atomistic amorphous samples were digitally prepared through fast quenching from the liquid states of copper and zirconium alloy. In both of the nanoindentation and uniaxial compression simulations, shear transformation zones and shear bands are observed through the local deviatoric shear strains in the samples. The results show that the existence of pores causes strain concentrations and greatly promotes the initialization and propagation of shear bands. Importantly, only pores reaching critical size can effectively facilitate the formation of multiple shear bands. It is also observed that hardening occurs through pore annihilation and the shear band stops in porous metallic glasses.     

Multiple kinks in lamellar linear polyethylene

Injection-moulded specimens made of linear polyethylene with preferred orientation of the molecular chains (c-axes) in the direction of injection were deformed in a bending test. Ultra-thin sections of the deformed material were made following chlorosulfonization. Examination using transmission electron microscopy revealed that deformational and superstructural elements can be elucidated simultaneously using this method. Deformation in the observed regions with multiple kink bands is found to be inhomogeneous and concentrated in two shearing processes: one along the borders of the kink band and the other within a kink band at an acute angle to the border of the band. It must be concluded from the formation of the lamellae in the kink bands that deformation, even within a kink band, is inhomogeneous and is predominantly concentrated in the shear zones, while the lamellar stacks lying between the shear zones appear under electron microscopy, to be nearly undeformed.     

室内声环境标准限值合理性实验研究

我国现行的结构传播固定设备室内噪声排放限值不尽合理。通过将白噪声滤波获得31.5~500 Hz各倍频程带宽样本,调整其声压级至标准限值后合成原始声样本,并适当调整各倍频程频带声压级,合成新的声样本,采用成对比较法,对比研究各声样本的主观烦恼。结果表明,在A声级或响度级相同情况下,降低31.5 Hz与63 Hz倍频程频带声压级,并提高125 Hz、250 Hz及500 Hz倍频程频带声压级,声样本主观烦恼均小于原始声样本;在各倍频程中,31.5 Hz倍频程频带声压级与声样本主观烦恼度最为相关,且呈显著正相关（p < 0.01）,Pearson相关系数为0.925~0.951。     

Dual frequency band antenna combined with a high impedance band gap surface

A compact dual-band antenna structure for automotive and aerospace applications is discussed. A bow tie dual-band electromagnetic band gap (EBG) element geometry is presented that has a reduced cell dimension compared to the wavelength yet has sufficient bandwidth for mobile communication applications. The EBG was combined with a printed planar monopole to produce a structure 8 mm thick. The return loss and radiation patterns gave satisfactory performance at two frequency bands with bandwidths of 11% at 1700 MHz and 7% at 2600 MHz. There was suppression of the back radiation at both bands of 5 dB or better even for the small 3 times 3 element EBG used and the antenna was platform tolerant.