炭化造孔法制备木屑氯化钙复合吸附剂

为了解决氯化钙吸脱附氨气过程中的膨胀结块以及提高氯化钙基复合吸附剂的传质性能,本文采用浸泡的方法将氯化钙嵌入木屑中,然后采用高温炭化的方法将氯化钙木屑混合物炭化造孔制备复合吸附剂.SEM图像以及元素分析表明,在700°C的炭化温度下,氯化钙木屑炭化后所制备的复合吸附剂具有发达的孔隙结构,而且氯化钙均匀的分散在吸附剂中.复合吸附剂对氨气的吸附性能测试表明：在蒸发温度为5°C,冷凝温度为40°C的工况下,吸附时间为5,10和15min时,吸附量分别为0.204,0.253和0.285kg/kg,SCP（单位质量吸附剂的制冷功率）分别为868.96,540.02和405.16W/kg,平均吸附速率分别为6.79×104,4.22×104和3.17×104（kg/kg）/s,同时解决了氯化钙的膨胀结块.     

高吸水性能的新型复合吸附剂SiO2·xH2O·yCaCl2的孔隙结构测试与分析

介绍了一种由粗孔球形硅胶和氯化钙组成的新型复合吸附剂SiO₂·xH₂O·yCaCl₂. 为了分析它的吸附机理, 对粗孔球形硅胶和4个不同氯化钙含量的复合吸附剂, 采用扫描电子显微镜技术和ASAP2010吸附仪测试了它们的氮气吸附/解吸等温线、BET比表面积、孔径分布、孔容和平均孔径. 通过分析吸附、解吸等温线和滞后圈的形状, 推断出了粗孔球形硅胶和复合吸附剂的孔道结构主要包括两种类型: 一端开口的圆锥形和两端开口的圆锥形或双曲锥形管状孔隙. 通过对比分析孔径的分布, 结合滞后圈的形状, 给出了氯化钙在粗孔球形硅胶孔隙中填充过程的示意图. 实验测得了复合吸附剂和常用吸附剂(粗孔球形硅胶、细孔球形硅胶和分子筛13X)的25℃吸水等温线, 结果表明: 复合吸附剂的吸水量明显高于常用吸附剂的吸水量, 并结合孔隙分析结果对吸附等温线和液解现象进行了分析.     

壳聚糖磁性光敏剂血卟啉衍生物微球的制备及其体外表征研究

目的制备壳聚糖包覆的磁性光敏剂血卟啉衍生物微球并考察其体外表征。方法以五羰基铁为原料制备羰基铁粉纳米颗粒,非溶剂法将羰基铁粉纳米颗粒与光敏剂血卟啉衍生物HPD复合,并用壳聚糖包覆制备成壳聚糖包覆磁性血卟啉衍生物微球(CS-M-HPD)。使用电子显微镜、激光粒度仪、X-射线衍射仪和磁力测定仪考察微球的表征。结果检测结果表明该微球为球形,分散性良好,粒径大多集中在290～300 nm。微球羰基铁粉纯度高,呈现优良磁性。结论本研究实现了壳聚糖对磁性HPD的包覆,得到了单分散性磁性HPD微球,为进一步研究该微球靶向光动力治疗肿瘤的生物活性奠定了实验基础。     

陶瓷颗粒(纤维)增强聚合物复合电子封装与基板材料

本文论述了陶瓷颗粒(纤维)增强聚合物基复合电子封装与基板材料体系和性能特点,介绍了复合基板材料的实验研究和理论研究进展情况,根据实验研究和文献报道并结合目前在微电子封装领域广泛应用的环氧塑封材料,对复合电子封装与基板材料的发展趋势进行了分析和评述。     

聚乳酸复合材料研究进展

生物降解材料聚乳酸受其本身的化学结构限制,具有较高的结晶性,从而限制了其广泛应用.而拓宽聚乳酸应用的最重要的途径是聚乳酸复合材料的制备.本文综述了聚乳酸复合改性研究进展,主要侧重于碳纳米管、环糊精、羟基磷灰石及其它物质与生物降解材料-聚乳酸的复合改性最新进展.聚乳酸基复合材料的结晶性、亲水性、生物相容性与纯聚乳酸材料对比,得到了明显的提高.最后对其发展进行了展望.     

一种能同时吸附水中多种污染物的新型吸附材料:表面活性剂改性沸石

表面活性剂改性沸石是指将粉煤灰合成沸石后,使用十六烷基三甲基溴化铵进行表面修饰获得的一种新型吸附材料.本文评估了表面活性剂改性沸石从水中同时去除多类污染物的多功能性.目标污染物包括无机离子型污染物(氨氮和磷酸盐)、有机离子型污染物(亚甲基蓝和腐植酸)、可离子化有机污染物(不同pKa的双酚A,-氯酚和苯酚)和不可离子化的有机污染物(不同疏水性的苯胺,硝基苯,萘).与合成沸石相似,表面活性剂改性沸石吸附氨氮和磷的能力也较强.沸石内部孔隙中的负电荷可以去除氨氮;粉煤灰中的CaO,Al2O3和Fe2O3等成分经过沸石合成过程中的修饰可以吸附磷.研究结果还表明:尽管合成沸石对腐植酸,可离子化和不可离子化的有机污染物没有亲和性,表面活性剂改性沸石却对上述污染物具有很强的吸附能力.表面活性剂在沸石表面形成了双层胶束,使沸石外表面具有了疏水性,因此,可以吸附有机污染物.本研究表明表面活性剂改性沸石是一种很有前途的多功能水处理吸附剂.     

CeO_2对锂离子电池正极材料LiMn_(1/3)Co_(1/3)Ni_(1/3)O_2的包覆改性

采用溶胶凝胶法对LiMn1/3Co1/3Ni1/3O2表面包覆了1.0wt%的CeO2.采用X射线衍射(XRD),扫描电镜(SEM),循环伏安(CV)和恒流充放电对包覆和未包覆的LiMn1/3Co1/3Ni1/3O2进行了结构表征与性能测试分析.研究显示,CeO2并没有改变电极材料的晶体结构,仅在电极材料表面形成均匀的包覆层.包覆1.0wt%CeO2后的材料的放电容量和循环性能均明显优于未包覆的材料.在20mA·g-1的电流密度下,包覆1.0wt%CeO2后的材料的放电容量为182.5mAh·g-1而未包覆的材料仅为165.8mAh·g-1.包覆1.0wt%CeO2后的材料在3.0C下循环12周后的容量保持率达93.2%,而未包覆的材料的容量保持率仅为86.6%.CV测试表明,CeO2包覆层可以有效的防止正极材料与电解液的直接接触,抑制了材料结构的转变或抑制了与电解液的副反应,从而提高了材料的电化学性能.     

CeO2对锂离子电池正极材料LiMn1/3CO1/3Ni/3O2的包覆改性

采用溶胶凝胶法对LiMn1/3CO1/3Ni/3O2表面包覆了1．0wt％的CeO2．采用X射线衍射（XRD）,扫描电镜（SEM）,循环伏安（CV）和恒流充放电对包覆和未包覆的LiMn1/3CO1/3Ni/3O2进行了结构表征与性能测试分析．研究显示,CeO2并没有改变电极材料的晶体结构,仅在电极材料表面形成均匀的包覆层．包覆1．0wt％CeO2后的材料的放电容量和循环性能均明显优于未包覆的材料．在20mA·g^-1的电流密度下,包覆1．0wt％CeO2后的材料的放电容量为182．5mAh·g^-1而未包覆的材料仅为165．8mAh·g-1．包覆1．0wt％CeO2后的材料在3．0C下循环12周后的容量保持率达93．2％,而未包覆的材料的容量保持率仅为86．6％．CV测试表明,CeO2包覆层可以有效的防止正极材料与电解液的直接接触,抑制了材料结构的转变或抑制了与电解液的副反应,从而提高了材料的电化学性能．     

改性秸秆膨胀床与固定床吸附去除SO_4~(2-)

含硫酸根离子(SO42-)废水可对环境造成危害,在排放之前需降低SO42-浓度.本文利用改性秸秆阴离子吸附剂制备吸附柱,分别在膨胀床和固定床操作下进行动态吸附实验,研究改性秸秆阴离子吸附柱去除SO42-的性能.结果表明,在改性秸秆膨胀床操作中,膨胀率随流速提高而线性增大;随膨胀率的增加,膨胀床去除SO42-的穿透时间缩短,柱吸附量降低,膨胀率不宜大于25%;在改性秸秆固定床操作中,随高径比的增加,吸附柱去除SO42-的穿透时间延长;而随进水SO42-浓度和流量的增加,床层工作时间显著缩短;在实验流量下,膨胀床的处理效果略优于固定床.SO42-解吸实验表明,0.1 mol/L NaOH溶液解吸效果最佳,是合适的吸附柱再生液.     

微生物细胞电镀磁性金属化研究

本文以钝顶螺旋藻细胞为模板,通过电镀工艺在其表面沉积磁性合金来制造螺旋形磁性微粒,对微生物细胞电镀磁性金属化工艺进行研究.通过光学显微镜、扫描电子显微镜、电子能谱、X射线衍射、振动样品磁强计等对电镀磁性化后螺旋藻的细胞形态、表层成分、相结构及静磁性能进行观察与分析.结果表明螺旋藻细胞经电镀处理后表面包覆上一层不含非金属相的铁磁性材料,实现了微生物细胞电镀磁性金属化,这为生物约束成形技术提供了新工艺.在金属化过程中,微生物形体保持良好,细胞表面镀层厚度均匀,镀层为面心立方结构的NiFe合金,颗粒具有软磁特性.此外,对微生物细胞电镀磁性金属化工艺过程的电化学反应机理进行了分析,表明NiFe合金在微生物表面的沉积为异常共沉积.     

Colcemid effects on homologue pairing and crossing over during fetal mouse oogenesis

Summary Colcemid was administered to gestational day 13 female mice to test effects on homologue pairing, synapsis and recombination of fetal oogenesis. Pairing abnormalities were detected in pachytene oocytes by light and electron microscopy examination of bivalents and synaptonemal complexes. Reduction of total chiasmata per treated diplotene oocyte (22.74) compared to controls (31.07) was found.     

Colcemid effects on homologue pairing and crossing over during fetal mouse oogenesis

Colcemid was administered to gestational day 13 female mice to test effects on homologue pairing, synapsis and recombination of fetal oogenesis. Pairing abnormalities were detected in pachytene oocytes by light and electron microscopy examination of bivalents and synaptonemal complexes. Reduction of total chiasmata per treated diplotene oocyte (22.74) compared to controls (31.07) was found.     

Use of a new process of metallic shadowing by cathodic vaporization for scanning electron microscopy of tegumental products of insects]

In scanning electron microscopy, the recent process, not yet much used, of coating subjects with gold by cathodic sputtering, allows one in biology and especially in entomology, to visualize microreliefs, habitually masked, when the old technique called evaporating technique, was used. This process effectively allows one to deposit a very much thinner layer of metal and, because it is performed at room temperature, prevents artifacts caused by the high temperature necessitated by the other technique, whose previous results nevertheless remain generally correct.     

Homologous recombination in plants

In plants three different approaches have been used to study homologous DNA recombination; extrachromosomal recombination (ECR) between transfected DNA molecules, intrachromosomal recombination (ICR) between repeated genes integrated into and resident at the genome and recombination between introduced DNA and homologous sequences in the genome (gene targeting). ECR is efficient (10^–1 to 10^–3) and occurs mainly during a limited time period early after transfection. It proceeds predominantly via nonconservative single-strand annealing. ICR, which in most cases is described best by the double-strand break repair model of recombination, occurs at frequencies of one event in 10⁵ to 10⁷ cells. ICR takes place throughout the whole life-cycle of a plant, in all organs and at different developmental stages. As there exists no predetermined germline in plants, somatic recombination events can be transferred to the next generation. Recombination frequencies are enhanced by DNA damage. Gene targeting, like ICR, occurs at low rates in plant cells. Almost nothing is known about the enzymes involved in homologous recombination in plants.     

Myelin architecture: zippering membranes tightly together

Rapid nerve conduction requires the coating of axons by a tightly packed multilayered myelin membrane. In the central nervous system, myelin is formed from cellular processes that extend from oligodendrocytes and wrap in a spiral fashion around an axon, resulting in the close apposition of adjacent myelin membrane bilayers. In this review, we discuss the physical principles underlying the zippering of the plasma membrane of oligodendrocytes at the cytoplasmic and extracellular leaflet. We propose that the interaction of the myelin basic protein with the cytoplasmic leaflet of the myelin bilayer triggers its polymerization into a fibrous network that drives membrane zippering and protein extrusion. In contrast, the adhesion of the extracellular surfaces of myelin requires the down-regulation of repulsive components of the glycocalyx, in order to uncover weak and unspecific attractive forces that bring the extracellular surfaces into close contact. Unveiling the mechanisms of myelin membrane assembly at the cytoplasmic and extracelluar sites may help to understand how the myelin bilayers are disrupted and destabilized in the different demyelinating diseases.     

Genetic characterization of the new morphological and UV-sensitive mutants in Coprinus cinereus. I. A UV-sensitive mutation rad 1 associated with elevated frequencies of mitotic and meiotic recombination

Studies on the effect of an UV-sensitive mutation, rad 1, in meiotic and mitotic recombination in Coprinus indicated that, in homozygous condition, rad 1 increased the spontaneous meiotic recombination by 50% and UV-induced mitotic intergenic recombination by about 5-fold. The homozygous rad 1 diploid was shown to be much more sensitive to the recombinogenic effects of polyfunctional than than of mono- or non-functional alkylating agents.     

Life without oxygen: what can and what cannot?

The basic principles involved in the biotransformation of organic carbon compounds in the absence of molecular oxygen (dioxygen) are presented in this paper. The role of various electron acceptors during the breakdown of organic compounds is discussed and the metabolic end-products expected are summarized. The different biochemical possibilities and strategies for the anaerobic degradation of organic matter and the metabolic response of some organisms to anaerobiosis are elucidated. Positive and negative effects of anaerobiosis on environmentally relevant processes and their influence on man and on animals are reviewed. Finally, some examples of the biotechnological application of anaerobic processes are presented.     

Homologous recombination in fission yeast: Absence of crossover interference and synaptonemal complex

The study of homologous recombination in the fission yeastSchizosaccharomyces pombe has recently been extended to the cytological analysis of meiotic prophase. Unlike in most eukaryotes no tripartite SC structure is detectable, but linear elements resembling axial cores of other eukaryotes are retained. They may be indispensable for meiotic recombination and proper chromosome segregation in meiosis I. In addition fission yeast shows interesting features of chromosome organization in vegetative and meiotic cells: Centromeres and telomeres cluster and associate with the spindle pole body. The special properties of fission yeast meiosis correlate with the absence of crossover interference in meiotic recombination. These findings are discussed. In addition homologous recombination in fission yeast is reviewed briefly.This article is dedicated to Urs Leupold, the founder of fission yeast genetics.     

Structure and function of RecA-DNA complexes

While theE. coli RecA protein has been the most intensively studied enzyme of homologous recombination, the unusual RecA-DNA filament has stood alone until very recently. It now appears that this protein is part of a universal family that spans all of biology, and the filament that is formed by the protein on DNA is a universal structure. With RecA's role in recombination given new and greatly increased significance, we focus in this review on the energetics of the RecA-mediated strand exchange and the relation between the energetics and recombination spanning heterologous inserts.