末端带苯并噁嗪环的树枝状高分子的合成

采用溶剂法,以1.0G PAMAM和2.0G PAMAM为原料,与苯酚、多聚甲醛反应分别制备了2种新型的树枝状苯并噁嗪：1.0G苯并噁嗪(1.0G BZ)和2.0G 苯并噁嗪(2.0G BZ).利用H NMR,FT-IR和DSC对其结构和固化行为进行了表征.通过TGA考察了所得聚合物的耐热性能.     

长庆油田废弃钻井液固化处理研究

废弃钻井液是石油钻井过程中产的污染物,如不经处理任意排放,就会污染当地的环境,造成难以估量的损失。笔者在调研国内外废弃钻井液固化处理研究现状的基础上,探讨了长庆油田废弃钻井液对环境的影响,研究了几种固化方法的固化效果,并对固化机理做了初步的分析。通过研究表明:采用无机固化剂GHW-3为主,辅以适量的有机固化剂GHY-1及无机添加剂和填料复合固化剂的固化方法,其固化物固化强度高,经固化后的固化物浸出液毒性检测其毒性远小于国家环保指标,具有明显的社会与环境效益,有一定的推广应用前景。     

室温固化丙烯酸酯胶粘剂

该文通过对室温固化丙烯酸酯胶粘剂的研制，探讨了其固化机理；并对该胶粘剂的粘接范围、粘接强度及粘接性能进行了测试。实验表明，所研制的这种胶粘剂可广泛应用于机械、电子和室内装饰等行业。     

黑麦草对苯并[a]芘污染土壤的根际修复及其酶学机理研究

采用室内盆栽试验方法,研究了黑麦草（Lolium multiflorum L.）对多环芳烃苯并[a]芘污染土壤的修复作用。结果表明。土壤中苯并[a]芘的可提取态浓度随着时间延长而逐渐减少,黑麦草加快了土壤中可提取态苯并[a]芘浓度的减少,提高了苯并[a]芘在土壤中的降解率,在1、10、50mg·k^-1苯并[a]芘处理浓度下,黑麦草生长土壤中苯并[a]芘的降解率分别达90．3％、87．5％、78．6％;而没有黑麦草生长土壤中苯并[a]芘的降解率则为79．3％、66。4％、55．6％。黑麦草根系增强了土壤中多酚氧化酶和脱氢酶的活性以及增加土壤中微生物碳的含量,从而提高植物对苯并[a]芘的降解率。植物的地上部也可积累少量苯并[a]芘,但植物对苯并[a磁的吸收不是黑麦草对其修复的主要机制。土壤自身具有修复苯并[a]芘的潜能．种植黑麦草具有强化土壤修复苯并[a]芭污染的作用．     

镀锌厂工业废水中锌离子的固化效果

为确定最佳固化参数,达到对锌离子的最佳固化量,研究了固化剂、养护时间和固化温度对不同pH镀锌厂工业废水中锌离子的固化效果。试验结果表明:水泥固化最佳固化参数是pH 7.0、养护时间21 d、固化温度25℃、固化剂添加比例60%水泥和40%蛭石,在此处理下,制得的水泥固化块锌离子浸出浓度最低,为0.029 mg/L;石灰固化最佳固化参数是pH 7.0、养护时间14 d、固化温度25℃、固化剂添加比例60%石灰、30%水泥和10%沙砾,在此处理下,制得的石灰固化块中锌离子浸出浓度最低,为0.156 mg/L。使用XRD对按照最佳固化参数制得的水泥固化块和石灰固化块进行矿物成分分析,其主要矿物成分均为辉石,比较水泥固化块和石灰固化块锌离子浸出浓度可知,水泥固化优于石灰固化,因此建议水泥固化作为镀锌厂工业废水中锌离子的首选固化工艺。     

湿热协同对酚醛树脂胶粘剂固化的影响

主要利用TG、DSC及SEM技术研究了水分与温度对酚醛树脂固化程度与固化速率的影响。结果表明,温度越高,酚醛树脂固化速率越大,水分的存在影响了酚醛树脂的固化度,在水分无法挥发条件下的酚醛树脂与正常固化的酚醛树脂相比硬度较低,容易被击溃,性能较差。对两者进行TG-DSC分析,前者的TG-DSC曲线表明其存在剧烈失重并仍有一吸热峰,而后者的TG-DSC曲线较为平缓,说明水分的存在影响了酚醛树脂的交联缩聚。     

UV自由基固化和阳离子固化涂层的比较研究

对 U V自由基固化和阳离子固化两种机理进行了对照试验 .考察了温度和 O2 对固化速度的影响 ,涂层性能及它们作为 UV固化涂料、油墨的优缺点 ,并从理论上进行了分析 .U V自由基固化和阳离子固化的固化速度随温度的升高而加快 ,并且自由基的固化速度大于阳离子固化速度 .自由基固化体积收缩大 ,附着力差 ;阳离子固化体积收缩小 ,附着力优异 .氧对自由基固化有显著的阻聚作用 ,而对阳离子固化没有阻聚效应 .此外 ,阳离子固化存在“暗反应”,当移走 UV光源后 ,仍会发生固化反应     

1,5—苯并硫氮杂—α—氯代—β—内酰胺的合成

1 ,5—苯并硫氮杂 艹卓 与氯乙酰氯反应合成了一类新型的 1,5—苯并硫氮杂艹卓 —α—氯代—β—内酰胺衍生物 ,其结构由元素分析、氢谱、质谱和红外谱图证实。     

对羟基苯甲醇对小白菜天麻素积累和生长的影响

利用植物水培法,探讨营养液中添加对羟基苯甲醇,小白菜能否产生和积累天麻素,并进一步研究对羟基苯甲醇对小白菜生长的影响。结果显示,小白菜能以浓度依赖的方式将对羟基苯甲醇转化为天麻素,并在水培第6天达到最高值,但随着时间的推移,天麻素积累量逐渐降低。说明小白菜体内存在识别对羟基苯甲醇的糖基转移酶,由其催化生成的天麻素因进一步代谢而很难在小白菜中长期积累。水培营养液中添加对羟基苯甲醇,会抑制小白菜根的生长并延缓或阻滞株高的增大,但小白菜能在较短时间和一定浓度范围内抵抗对羟基苯甲醇的危害,而且这种抵抗能力与对羟基苯甲醇浓度和施加时间呈负相关。以上研究结果为以后大规模利用小白菜既经济又高效地水培生成天麻素,并进一步将其开发成为一种保健蔬菜奠定了基础。     

山茶籽3种工艺制油酸价、过氧化值和苯并[a]芘的比较

通过对浸出油、土榨油和冷榨油等3种不同工艺制取油,酸价、过氧化值和苯并[a]芘等质量安全指标进行测试分析,以探明不同加工工艺对茶籽油品质与食用安全性的影响。研究表明,3种工艺制取油,其酸价、过氧化值和苯并[a]芘随贮藏时间延长,总体变化呈增长态势。但3种工艺制油,酸价指标增幅分别为325.0%、136.0%和120.9%,质量安全指标合格率分别为20%、0和100%;过氧化值增幅分别为89.7%、46.1%和85.7%,合格率分别为20%、80%和100%;苯并[a]芘增幅分别为202.5%、177.8%和65.7%,合格率分别60%、40%和100%。因此,低温冷榨工艺制油,常温下在3 a贮藏期内,通过检测其酸价、过氧化值和苯并[a]芘增幅相对较少,分别是120.9%、85.7%和65.7%,且苯并[a]芘含量与贮藏时间的相关性不大,其质量合格率均为100%。其产品滋味柔和清香,色泽澄清透明,保持生理活性物质,质量风险可控,是一种高端木本油料植物食用油。     

炭化温度对木材液化物碳纤维原丝微结构的影响

为了扩大木材的应用领域和降低碳纤维的成本,以木材液化物为原料,加入六次甲基四胺熔融纺丝,经甲醛和盐酸溶液固化处理后获得木材液化物碳纤维原丝,利用IR、XRD、拉曼光谱分析仪等初步揭示了木材液化物碳纤维原丝在炭化过程中微结构的变化。结果表明:炭化温度400℃以上,木材液化物原丝中出现了较明显的（100）衍射峰;炭化温度500℃以上在1 360 cm -1处附近出现D峰、1 595 cm -1处附近出现G峰;随炭化温度的提高,原丝内部微观结构逐步趋于有序化;炭化过程中,原丝分别在500和800℃时结构发生了两次大的改变,但代表芳环骨架振动的1 632、1454 cm-1处吸收峰在整个炭化过程中依然存在,表明木材液化物原丝是一种难石墨化的高分子材料。      

Visualization of nucleolar genes

The presence of extrachromosomal nucleoli in amphibian oocytes has permitted isolation and electron microscopic observation of the genes coding for ribosomal RNA precursor molecules. Visualization of these genes is possible because many precursor molecules are simultaneously synthesized on each gene. Individual genes are separated by stretches of DNA that apparently are not transcribed at the time of synthesis of precursor rRNA in the extrachromosomal nucleoli.     

A key enzyme in the biogenesis of lysosomes is a protease that regulates cholesterol metabolism

Mucolipidosis II is a severe lysosomal storage disorder caused by defects in the α and β subunits of the hexameric N-acetylglucosamine-1-phosphotransferase complex essential for the formation of the mannose 6-phosphate targeting signal on lysosomal enzymes. Cleavage of the membrane-bound α/β-subunit precursor by an unknown protease is required for catalytic activity. Here we found that the α/β-subunit precursor is cleaved by the site-1 protease (S1P) that activates sterol regulatory element-binding proteins in response to cholesterol deprivation. S1P-deficient cells failed to activate the α/β-subunit precursor and exhibited a mucolipidosis II-like phenotype. Thus, S1P functions in the biogenesis of lysosomes, and lipid-independent phenotypes of S1P deficiency may be caused by lysosomal dysfunction.     

Neurotoxicity of a fragment of the amyloid precursor associated with Alzheimer's disease

Amyloid deposition in senile plaques and the cerebral vasculature is a marker of Alzheimer's disease. Whether amyloid itself contributes to the neurodegenerative process or is simply a by-product of that process is unknown. Pheochromocytoma (PC12) and fibroblast (NIH 3T3) cell lines were transfected with portions of the gene for the human amyloid precursor protein. Stable PC12 cell transfectants expressing a specific amyloid-containing fragment of the precursor protein gradually degenerated when induced to differentiate into neuronal cells with nerve growth factor. Conditioned medium from these cells was toxic to neurons in primary hippocampal cultures, and the toxic agent could be removed by immunoabsorption with an antibody directed against the amyloid polypeptide. Thus, a peptide derived from the amyloid precursor may be neurotoxic.     

溶质和硬质型桃果实成熟过程果肉多肽组学分析

【目的】 比较溶质型和硬质型桃在果实成熟过程中肽段和前体蛋白的差异,为挖掘决定或调控成熟过程的关键多肽提供理论依据。【方法】 通过多肽组学的方法,对溶质型（‘CN13’）和硬质型（‘CN16’）桃内源性多肽特征以及前体蛋白功能进行分析,对比两种肉质桃果实在成熟衰老过程中前体蛋白和多肽的相对含量,并对差异肽段前体蛋白进行富集分析。【结果】 本研究分别提取了‘CN13’和‘CN16’两个时期（S3和S4III）的内源性肽样品进行质谱检测,共鉴定到473个前体蛋白,包含特异性肽段序列2 580条。对肽段的分子量、等电点以及剪切位点进行归纳整理,并对内源性肽段所对应的高丰度前体蛋白进行COG功能注释和pathway富集分析,结果显示前体蛋白主要参与一般功能预测、翻译后修饰、蛋白质转换、能量产生和转换以及碳水化合物运输与代谢等过程。差异肽段前体蛋白的富集分析表明,‘CN13’在成熟过程中差异肽段前体蛋白与氧化还原、活性氧代谢和电子传递链等生物学过程相关,主要参与糖酵解/糖异生、磷酸戊糖途径和RNA转运等途径;而‘CN16’差异肽段前体蛋白是与金属离子反应、无机物反应和镉离子反应等生物学过程相关,主要参与多种环境下微生物新陈代谢、剪接体和RNA转运等途径;同处在S4III时期的‘CN16’和‘CN13’差异肽段前体蛋白与基因表达、翻译和细胞大分子生物学过程相关,主要参与RNA降解、RNA转运和剪接体等途径。【结论】 ‘CN13’和‘CN16’果实在成熟过程中多肽差异显著,差异肽段前体蛋白主要涉及淀粉/蔗糖代谢、糖酵解和核糖体合成等途径,暗示这些代谢途径与桃果实成熟衰老关系密切,为进一步挖掘调控桃果实成熟衰老过程的关键多肽提供了理论参考。     

Plasticity and differentiation of embryonic retinal cells after terminal mitosis

The relation between terminal mitosis and the events that determine the developmental fate of embryonic precursor cells is not well understood. This relation has now been investigated with [3H]thymidine autoradiography to determine the time of cell birth and with a culture system that allows the testing of the developmental potential of cells isolated from the chick embryo retina. Contrary to the situation in vivo, where neuronal differentiation always precedes photoreceptor differentiation, photoreceptor differentiation occurs prematurely and precedes neuronal differentiation when precursor cells are isolated from the retina at early embryonic stages. Thus, cells born by embryonic day 5 (ED-5) give rise predominantly to photoreceptors when isolated for culture on ED-6 but develop mainly as neurons when isolated on ED-8. This suggests that retinal precursor cells retain after terminal mitosis the capacity to develop either as neurons or as photoreceptors. Moreover, photoreceptor differentiation appears to represent a constitutive or "default" pathway that precursor cells follow in the absence of neuron-inducing signals.     

All-Carbon Molecules: Evidence for the Generation of Cyclo[18]carbon from a Stable Organic Precursor

The unambiguous structural characterization of a single-sized all-carbon molecule requires its chemical synthesis. For cyclo[18]carbon, ab initio calculations predict a relatively stable, cyclic D9h ground state geometry with alternating C-C (1.36 angstroms) and C identical withC (1.20 angstroms) bonds. The synthesis and x-ray crystal structure of a direct precursor to C(18) are described. The analysis of laser flash heating experiments on this precursor by time-of-flight mass spectroscopy shows a sequence of retro-Diels-Alder reactions leading to C(18) as the predominant fragmentation pattern. Structural evidence is provided for the generation of an all-carbon molecule from a well-characterized organic precursor.     

The structure of rat preproatrial natriuretic factor as defined by a complementary DNA clone

The structure of rat preproatrial natriuretic factor ( preproANF ) was determined by nucleotide sequence analysis of an ANF complementary DNA clone. PreproANF is composed of a hydrophobic leader segment (20 amino acids), a precursor containing one glycosylation site (106 amino acids), and ANF (24 amino acids). Atrial natriuretic factor is located at the carboxyl terminus of the precursor molecule. The human, mouse, and rat genomes each contain a single ANF gene which is highly conserved.     

Tripeptide structure of bursin, a selective B-cell-differentiating hormone of the bursa of fabricius

Differentiation of lymphoid precursor cells in a variety of species is induced by polypeptide hormones such as thymopoietin for T cells and bursin for B cells. In the present experiments, bursin isolated from the bursa of Fabricius of chicken was found to induce the phenotypic differentiation of mammalian and avian B precursor cells but not of T precursor cells in vitro. Similarly, bursin increased cyclic guanosine monophosphate in cells of the human B-cell line Daudi but not in cells of the human T-cell line CEM. These inducing properties of bursin are the reverse of the inducing properties of thymopoietin produced by the thymus and are appropriate to a physiological B-cell-inducing hormone. A tripeptide sequence (lysyl-histidyl-glycyl-amide) was determined for bursin and confirmed by synthesizing this proposed structure and demonstrating chemical identity of the natural and synthetic peptides. Similarity of biological action was indicated in induction assays by elevation of cyclic adenosine monophosphate and guanosine monophosphate in Daudi B cells but not in CEM T cells.