北极耐冷假交替单胞菌的培养温度对其胞外蛋白酶合成的影响

从北极楚科奇海水中分离筛选到2株产蛋白酶耐冷细菌BSw20308及BSw20353.经分子鉴定为假交替单胞菌属.这2株菌虽存在较近亲缘关系,16S rDNA序列相似性为98%,但属于不同种,表型方面也存在差异.酶谱分析显示,此2株菌的胞外产物中存在至少3种蛋白水解活性组分.培养温度的变化对这2株菌胞外蛋白水解活性组分的生成具有不同的影响效果,表明极地海洋细菌可能在酶学水平上通过酶的种类与活力的调整和采取不同的策略来适应环境温度的变化.     

大菱鲆病原鳗弧菌生物学及分子特征研究

从山东沿海养殖发病大菱鲆分离了5株鳗弧菌。5株菌对大菱鲆有较强的致病性,LD50范围为2.32×101～4.03×102cfu/g鱼;5株菌分别属于O1、O2、O3血清型,菌株之间的16SrRNA基因序列相似性范围97.1%～99.9%;与国外报道的鳗弧菌的序列相似性范围为89.7%～99.9%。5株菌的生理生化特征与鳗弧菌标准菌株一致,能产生多种胞外酶和溶血素;都含有金属蛋白酶基因和溶血素基因,其中3株菌各含有一个67kb大质粒。病原菌对青霉素、苯唑青霉素、氨苄青霉素、先锋霉素Ⅳ、先锋霉素Ⅴ、先锋霉素Ⅵ、链霉素、强力霉素、洁霉素、万古霉素、灭滴灵等11种常用抗菌药物有抗性,只对新生霉素、呋喃妥因、利福平、新霉素等4种药物敏感。     

海水附着细菌多样性和群落演替的研究

通过细菌16S rRNA基因(16S rDNA)文库方法研究了1至7天近海浸海玻片附着细菌的多样性和群落演替特征.从1至7天3个基因文库中共筛选了269个克隆、144个有效分类操作单元 (OUT)并对其全部测序.16S rDNA序列系统进化分析发现,这些细菌主要归属于8个细菌门类:变形菌门(Proteobacteria)(α-、γ-和δ-亚群)、拟杆菌门(Bacteroidetes)、芽单胞菌门(Gemmatimonadetes)、厚壁菌门(Firmicutes)、浮霉菌门(Planctomycetes) 、光合细菌门(Cyanobacteria)、放线菌门(Actinobacteria)和酸杆菌门(Acidobacter ia).由此可知1周内变形菌门的α-亚群、γ-亚群和拟杆菌门的细菌是常见的附着类群;α-变形菌亚群中的玫瑰杆菌族(Roseobacter clade)是海洋环境中比较常见的早期附着种类;由聚类分析显示3天和7天细菌的群落结构相似.这些实验结果为了解海水附着细菌生物膜形成的演替过程提供了理论基础,并为海水微生物腐蚀控制提供了生物学线索.     

北极太平洋扇区深海沉积物的细菌多样性研究

对北极太平洋扇区4个站位深海表层沉积物样品,采用PCR结合变性梯度凝胶电泳(PCR-DGGE)技术进行了细菌16S rRNA基因V3区序列的系统发育分析.结果表明,沉积物中的细菌多样性丰富,获得的40条序列归属于4个细菌类群:变形细菌(Proteobacteria,占全部序列的75%)、噬纤维菌-屈挠杆菌-拟杆菌群(Cytophaga-Flexibacter-Bacteroides,CFB,占10%)、放线细菌(Actinobacteria,占10%)和酸杆菌(Acidobacteria,占5%).其中变形细菌(包括α、β、γ和δ-Proteobacteria),而γ-Proteobacteria占全部序列的62.5%,是很明显的优势类群.在这些细菌类群中,β、γ-Proteobacteria在4个站位沉积物中均有分布.     

海洋产蛋白酶细菌发酵液防污活性研究

传统的防污剂对海洋环境造成严重污染,随着环保意识的增强以及相关规定的制订,各国竞相开展新型无毒防污剂的研究。本文以海洋产蛋白酶菌株发酵产物为活性物质,研究蛋白酶粗提物对污损生物硅藻(navicula sp.)和贻贝(mytilus edulis)附着行为的影响。结果表明,所研究菌株的发酵液对硅藻(navicula sp.)和贻贝(mytilus edulis)的附着有明显抑制作用。贻贝(mytilus edulis)毒性实验显示,细菌发酵液对贻贝无毒。因此,海洋微生物蛋白酶产生菌粗酶提取物可以作为环保型防污功能添加剂。     

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。     

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。     

Pyrrosia petiolosa内生细菌筛选及其抑菌活性物质分析

为探究Pyrrosia petiolosa内生细菌的抑菌活性,采用植物组织分离和微生物传统培养法从其根、茎、叶共分离检测到内生细菌14株。通过滤纸片抑菌法筛选两株有显著抑菌活性的内生细菌G7、Y12,并借助GC-MS技术对这两株内生细菌进行抑菌活性成分检测与分析。研究表明:两株内生细菌经16S r DNA测序比对分别鉴定为Lysinibacillus sphaericus C3-41和Bacillus amyloliquefaciens FZB42。生长曲线测定结果显示菌株G7、Y12分别在16 h和12 h后进入稳定期。GC-MS检测鉴定到两株内生细菌发酵上清抑菌活性物质主要是有机酸类和2,5-二酮哌嗪衍生物。该研究可为挖掘P.petiolosa内生细菌药物活性、筛选抗菌药物新来源提供参考。     

四川传统腌腊肉制品中乳酸菌的分离鉴定及其抗氧化能力研究

为获得发酵特征满足肉类发酵剂要求同时具有抗氧化能力的潜力乳酸菌,从采集于四川省眉山等5市的7个传统腌腊肉样品中筛选乳酸菌,经16S r DNA鉴定,挑选出8株(L1-L8)乳酸菌,对其主要发酵特征和抗氧化能力进行评估。结果表明:有6株菌的主要发酵特征满足肉类发酵剂要求,即具有蛋白酶活性,不产NH3、生物胺、H2S和CO2,能够耐受6%Na Cl和150 mg/kg Na NO2,并能够在10~30℃生长;该6株菌的细胞悬浮液和无细胞提取液均具有清除羟自由基和DPPH自由基的能力,尤以L6的菌体作用最强,清除率分别达52.48%和24.16%;该6株菌细胞悬浮液和无细胞提取液均具有较强还原能力,而L2、L3、L4和L5则具有较强的抑制脂质过氧化能力,以L5最高,可达63.36%。综合来看,筛选菌株中L4既满足肉类发酵剂的要求,又具有较强抗氧化能力,有望开发成具有抗氧化能力的肉类发酵剂。     

青岛汇泉湾海洋趋磁细菌多样性研究

在青岛汇泉湾沿岸沉积物中发现了大量海洋趋磁细菌,最大丰度可达105 个/cm3.透射电镜观察发现该菌菌体形态多样,有球形或卵球形、长短杆状、弧状和螺旋状,其中球形或卵球形趋磁细菌占绝对优势.电镜观察还发现该菌磁小体的排列方式多样化,大多数呈链状排列,有单链、双链及多链,还有的呈环状或者成簇排列.磁小体的形态也多种多样,有正方体、棱柱体、立方八面体、子弹头状、片状和齿状.用RFLP方法分析了70个克隆测序,得到10条不同序列.经16S rRNA系统发育分析,发现9个属于α-变形菌亚纲,1个属于γ-变形菌亚纲,共有8个不同的属,优势种属于未培养的海洋趋磁球菌.所有菌株与最接近的海洋趋磁球菌的相似性并不高(76.4%～89.4%),表明该海区的趋磁细菌为新发现的微生物资源.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.