温度和环境对2维C/(SiC-BxC) n断裂韧性的影响

采用单边切口梁法研究了二维碳纤维增强碳化硼–碳化硅复合材料(2D C/(SiC–BxC)n)在空气和真空两种环境下断裂韧性与温度的关系,用扫描电镜观察断口微观形貌。结果表明:真空中2D C/(SiC–BxC)n复合材料的断裂韧性随温度升高而降低,室温下界面结合弱,残余热应力大,易发生纤维桥接裂纹,断裂韧性高;高温下相反。在空气中随温度升高断裂韧性增加,700℃达到最大值,尔后随温度升高而降低,这与生成的B2O3和SiO2.B2O3固溶体会封填裂纹以及碳相的氧化有关。     

Induction of apoptosis and apoptotic mediators in balb/C splenic lymphocytes by dietary n−3 and n−6 fatty acids

The present study was designed to investigate the effect of diatery n−6 and n−3 polyunsaturated fatty acids (PUFA) on anti-CD3 and anti-Fas antibody-induced apoptosis and its mediators in mouse spleen cells. Nutritionally adequate semipurified diets containing either 5% w/w corn oil (n−6 PUFA) or fish oil (n−3 PUFA) were fed to weanling female Balb/C mice, and 24 wk later mice were sacrificed. In n−3 PUFA-fed mice, serum and splenocyte lipid peroxides were increased by 20 and 28.3% respectively, compared to n−6 PUFA-fed mice. Further, serum vitamin F levels were decreased by 50% in the n−3 PUFA-fed group, whereas higher anti0Fas- and anti-CD3-induced apoptosis (65 and 66%) and necrosis (17 and 25%), compared to the n−6 PUFA-fed group, were found when measured with Annexin V and propidium iodide staining, respectively. In addition, decreased Bcl-2 and increased Fas-ligand (Fas-L) also were observed in the n−3 PUFA-fed group compared to the n−6 PUFA-fed group. No difference in the ratio of splenocyte subsets nor their Fas expression was observed between the n−3 PUFA-fed and n−6 PUFA-fed groups, whereas decreased proliferation of splenocytes was found in n−3 PUFA-fed mice compared to n−6 PUFA-fed mice. In conclusion, our results indicate that dietary n−3 PUFA induces higher apoptosis by increasing the generation of lipid peroxides and elevating Fas-L expression along with decreasing Bcl-2 expression. A reduced proliferative response of immune cells also was observed in n−3 PUFA-fed mice.     

Formation of C m H n (m ≥ 3, n ≤ m) hydrocarbons from C1 and C2 molecules by high‐temperature (≥1000°C), short‐contact‐time (1–10 ms) nozzle beam reactions

A nozzle, fabricated from nickel, molybdenum, iron, palladium, and quartz was utilized to produce longer chain hydrocarbons, C _m H _n (m ≥ 3, n≤ m) from C₂ (ethane, acetylene) and C₁ (methane) reactants at nozzle temperature range 1000–1150°C. The conversion of ethane was close to 100% at T _noz = 1000°C, while that of methane reached 20% at T _noz = 1150°C. The contact time in the nozzle is in the 10^-3–10^-2 s range. The reactions are first and higher order in reactant pressure. The reaction mechanism involves the formation of free radicals at the nozzle surface followed by gas‐phase reactions. This revised version was published online in July 2006 with corrections to the Cover Date.     

二维C/(BCχ-SiC)n复合材料的高温层间剪切性能

采用双槽口剪切法(double-notchcd shear,DNS)研究了二维(twodimensional,2D)碳乡纤维增强碳化硼-碳化硅[2DC/(BCx-SiC)]复合材料的高温层间剪切性能,用扫描电子显微镜观察断口彤貌.结果表明:在25～1200℃范围内.温度对2DC/(BCx-SiC)n复合材料的层间剪切强度有明显影响,在900℃时材料的层间剪切强度最高可达40.0MPa,分别比25℃和1200℃的商约13%和8%,略高于700℃的.此外,C/(BCx-SiC)n的层间剪切强度始终高于C/SiC的强度,且2种材料的层间剪切强度随温度变化规律相似.断口分析表明:层间剪切失效发生在基体内部或基体/纤维界面上,而纤维并没有受到损伤.     

Conductivite electrique totale de systemes a base d'iodure d'argent associe aux ionenes: polyiodure de n-propylene ou n-butylene dimethyl n,n-ammonium et polydiiodure n- butylene n′-propylene tetramethyl n,n,n′,n′- diammonium

Some linear ionenes (m–n), with the general formula {[NMe₂(CH₂)_mNMe₂(CH₂)_n]2I}_p (where Me = methyl group), have been prepared. The (3—3), (4—4) and 4—3) ionic polymers are associated with silver iodide, they provide materials the total electric conductivities of which are higher than that of beta AgI. In the case of the AgI-(3—3) system, the obtained value of the specific conductivity is 0.017 ohm cm⁻¹. This study involves compounds with equivalent AgI contents changing between 75 and 95%.     

粘(zhān)和粘(nían)

“粘”字是个多音字。一是念zhān(音沾),是个动词。意思是用胶或浆糊等把一种东西胶合在另一种东西上。如“粘贴标语”、“粘接剂”、“粘合剂”、“粘接协会”等等。另一种念法是念nían(音:年),是个形容词。意思是象浆糊或胶的性质如“粘液”、“粘稠”、“粘度”、“粘粘糊糊”等。我们在读音时应该注意别把“粘(zhān)接剂”念成“粘(nían)接剂”;也不要把“粘(nían)度”念成“粘(zhān)度”。     

Whole-body utilization of n−3 PUFA in n−6 PUFA-deficient rats

We evaluated the utilization of α-linolenic acid (18∶3n−3) in growing rats consuming a diet deficient in n−6 PUFA. After 90 d, whole-body 18∶3n−3 accumulation was 55% lower, total n−3 PUFA accumulation was 21% lower, and 18∶3n−3 disappearance was 14% higher in n−6 PUFA-deficient rats. Part of the reduction of whole-body 18∶3n−3 in n−6 PUFA-deficient rats was due to the 25% increase in net conversion of 18∶3n−3 to long-chain n−3 PUFA. Despite adequate 18∶3n−3 intake, n−6 PUFA deficiency decreased the accumulation of 18∶3n−3 and total n−3 PUFA.     

Co_n(n=1～5)在Mo_2C(001)面上的吸附性能研究

采用密度泛函理论方法对Co_n(n=1～5)团簇在Mo_2C(001)表面上的吸附性能进行了理论研究,找到了稳定的吸附结构,计算了吸附能。计算得知,三维吸附模式不稳定;在n=1～4时,聚集吸附模式和分散吸附模式可以共存;当n=5时,聚集吸附模式更稳定。     

集成橡胶C-(BR-SBR)n及C-(IR-SBR)n结构研究

研究了多锂体系集成橡胶SIBR的结构和玻璃化转变温度,研究结果表明所合成的聚合物呈三峰分布,并存在两个玻璃化转变温度,具有微观相分离结构。     

氧化锌n型导电机理研究进展

氧化锌是一种宽禁带半导体,在太阳能、光电显示等方面有广泛的应用.制约其应用的是p型氧化锌很难得到,其中一个原因在于本征氧化锌n型导电的原因不明确.本文综述了氧化锌n型导电的机理,重点分析了本征缺陷和非故意掺杂氢对氧化锌n型导电的影响.     

n－辛醇的制备方法

ｎ－辛醇的制备方法有用椰子油或棕榈仁油为原料的方法和以乙烯或丁二烯为原料的合成方法。１　用椰子油为原料的方法椰子油在铜—铬催化剂的存在下高压加氢，将得到的（粗）醇通过减压蒸馏进行精制。花王公司实施该技术。２　用乙烯为原料的方法以乙烯为原料，用齐格勒法...     

低成本C/C复合材料研究进展

炭/炭(C/C)复合材料作为一种高温性能优异,抗烧蚀,耐高温的材料,被广泛应用在航空航天等高技术工程领域。然而高昂的原材料,复杂的生产工艺,较长的生产周期带来了相当昂贵的生产成本,并严重制约了碳/碳复合材料在更多领域的应用。本文从预制体的低成本制造、低成本致密化工艺两大方面对C/C复合材料的低成本制造进行了综述。     

硅烷（CH3）m（C6H5）nSiCL4—m—n的Rochow合成

用高效ＲＳＰ－Ｓｕ３Ｓｉ合金催化剂，气化的氯苯ＰｈＣｌ与氯甲烷在４００℃同时经过催化剂ＲＳＰ－Ｃｕ３Ｓｉ可制得重要硅烷化试剂（ＣＨ３）ｍＰｈｎＳｉＣｌ４－ｍ－ｎｏ讨论了反应的最佳条件及速度。     

n(CH3)/n(Si)对甲基硅树脂防水性能的影响

以甲基三乙氧基硅烷和二甲基二乙氧基硅烷或羟基硅油为原料,分别制备了n(CH3)/n(Si)值为1·2、1·4、1·6的甲基硅树脂;考察了n(CH3)/n(Si)值对甲基硅树脂防水性能的影响。结果表明,以甲基三乙氧基硅烷和二甲基二乙氧基硅烷制备的甲基硅树脂,当n(CH3)/n(Si)值为1·2时,具有良好的防水性能;以甲基三乙氧基硅烷和羟基硅油为原料制备的甲基硅树脂,随着n(CH3)/n(Si)值的增大,经其处理的试件的吸水率比减小,与水的接触角增大;综合考虑吸水率比和耐碱性能,n(CH3)/n(Si)值为1·4的硅树脂具有最优的防水性能,并有望具有较持久的防水保护功能。     

超声辐射下n(Mg)∶n(Al)水滑石催化合成

通过低饱和共轭沉淀法制备了不同n(Mg)∶n(Al)的水滑石，并用XRD和BET等技术对催化剂前驱体进行了表征。XRD表征表明，水的加入使得水滑石的结构能够得到部分重建。同时水的加入使水滑石表面的O^2- 生成了相应的B碱(OH^-)，大大提高了催化活性。BET表征结果表明，水滑石作为碱性催化剂的活性位点主要存在于暴露的板层边缘。以制备的水滑石为催化剂在超声辐射下合成了含有强吸电子取代基4,4′-二硝基查尔酮，并考察了超声、催化剂的组成、水合质量和溶剂对催化性能的影响。结果表明，当催化剂的n(Mg)∶n(Al)＝3.0、水合质量为其前驱体的35％和溶剂为甲醇时，在超声辐射下具有最高的催化活性，收率达91.3%，选择性为100%。     

Effects of dietary supplementation of rapeseed oil on metabolism of [1-<Superscript>14</Superscript>C]18∶1n−9, [1-<Superscript>14</Superscript>C]20∶3n−6, and [1-<Superscript>14</Superscript>C]20∶4n−3 in atlantic salmon heaptocytes

Atlantic salmon were fed fish meal-based diets supplemented with either 100% fish oil (FO) or 100% rapeseed oil (RO) from an initial weight of 85 g to a final average weight of 280 g. The effects of these diets on the capacity of Atlantic salmon hepatocytes to elogate, desaturate, and esterify [1-¹⁴C]18∶1n−9 and the immediate substrates for the Δ⁵ desaturase, [1-¹⁴C]20∶3 n−6 and [1-¹⁴C]20∶4n−3, were investigated. Radiolabeled 18∶1n−9 was mainly esterified into cellular TAG, whereas the more polyunsaturated FA, [1-¹⁴C]20∶3n−6 and [1-¹⁴C]20∶4n−3, were primarily esterified into cellular PL. More of the elongation product, [1-¹⁴C]20∶1n−9, was produced from 18∶1n−9 and more of the desaturation and elongation products, 22∶5n−6 and 22∶6n−3, were produced from [1-¹⁴C]20∶3n−6 and [1-¹⁴C]20∶4n−3, respectively, in RO hepatocytes than in FO hepatocytes. Further, we studied whether increased addition of [1-¹⁴C]18∶1n−9 to the hepatocyte culture media would affect the capacity of hepatocytes to oxidize 18∶1n−9 to acid-soluble products and CO₂. An increase in exogenous concentration of 18∶1n−9 from 7 to 100 μM resulted in a nearly twofold increase in the amount of 18∶1n−9 that was oxidized. The conversion of 20∶4n−3 and 20∶3n−6 to the longer-chain 22∶6n−3 and 22∶5n−6 was enhanced by RO feeding in Atlantic salmon hepatocytes. The increased capacity of RO hepatocytes to produce 22∶6n−3 was, however, not enought to achieve the levels found in FO hepatocytes. Our data further showed that there were no differences in the hepatocyte FA oxidation capacity and the lipid deposition of carcass and liver between the two groups.     

C/C复合材料高温抗氧化研究进展

综述了国内外C／C复合材料的高温抗氧化研究进展。阐述了C／C复合材料的氧化机理,具体介绍了内部改性和表面涂层抗氧化研究现状,并对以后的发展方向进行了展望。     

C/C复合材料改性技术研究进展

综述了国内外最近C/C复合材料基体改性与涂层改性技术研究进展.并对未来的进一步研究进行展望.     

C／C复合材料抗氧化研究现状

结合国内外近几年研究报道,综述了C／C复合材料抗氧化方法,对各种涂层系统进行评述。文章最后展望了C／C复合材料高温抗氧化保护的研究方向。