Wavelength demultiplexing with layered multiple Bragg gratings in LiNbO3:Fe crystal

Dense wavelength division multiplexing (DWDM) is an important technology for expanding the capacity of optical network. The optical component based on the superimposed Bragg gratings shows that it can be used as one of advantageous multichannel components because of its excellent angle and wavelength selectivities. An optimized method for recording multiple Bragg gratings for wavelength demultiplexing in optical telecommunication band is proposed to achieve gratings with equal diffraction efficiency. A structure of three layers with twenty four gratings is demonstrated in a LiNbO(3):Fe crystal by employing the optimized recording method. Then an initial wavelength demultiplexing experiment based on the formed gratings is carried out in optical telecommunication C-band. The results obtained by measuring and analyzing the transmitted spectra of the fabricated gratings show that the diffraction efficiencies of the gratings are uniform. It is suggested that this kind of multiple gratings can be used for increasing the number of the demultiplexed wavelengths in recording medium with unit volume for WDM.     

红透山选矿工艺的进展

用阶段磨矿部分混合浮选处理铜锌硫多金属硫化矿石，铜锌分离效果差，锌回收率低。两段磨矿，铜锌硫顺序优先浮选，辅以铜中矿再磨，锌精尾脱硫，锌尾浓缩选硫等技术措施，实现了无抑制剂铜锌分离，使锌回收率大幅度提高。如果进一步加强细磨，混合应用捕收剂，技术经济指标还会有新的突破。     

腐植酸微生物菌剂在滨海盐渍化土壤上的应用效果

通过筛选能够在高渗透压条件下生长繁殖的巨大芽孢杆菌和枯草芽孢杆菌,将它们作为功能微生物接种到腐植酸中,应用于滨海盐碱地改良,同化学改良法比较,盐碱地土壤理化性状显著改善,土壤微生物数量明显增多,生物量碳、土壤的呼吸作用和酶活性也有一定增加;枣长势良好,植株健壮,叶色浓绿,未出现盐碱化症状。3年生枣和7年生枣,平均株产达1.8 kg和28.6 kg,增产幅度明显。试验表明利用腐植酸微生物菌剂进行滨海盐碱地改良是一种经济有效的办法。     

高剂量率后装放疗辐射场的最优化研究

以某一高剂量率(HDR)后装治疗室为对象,利用蒙特卡罗程序计算放射源处于治疗室不同位置时迷宫内入口、迷宫内入口第一转折和迷宫外入口处γ辐射水平,分析研究放射源位置对迷宫内辐射场分布的影响,并通过现场实验检验其可靠性。结果表明,放射源位置对迷宫内辐射场分布有较大影响,在治疗室东侧且靠近迷宫内墙的区域时,迷宫外入口剂量相对较小,可推荐为治疗时放射源的最优化位置。     

村镇住宅受损木柱加固试验研究

本文通过对11根短木柱试件的轴压试验,研究了灌胶修补裂缝、纤维布的种类及用量对木柱受力性能的影响。试验结果表明,开裂木柱的承载能力和延性明显降低,灌胶修补裂缝可以提高木柱的承载能力,而粘贴玄武岩纤维布既可以提高开裂木柱的承载能力,又可以改善木柱的延性。     

碳钢交流电腐蚀机理的探讨

开展了碳钢交流电腐蚀失重试验及交流干扰下极化曲线测量,结果表明,在研究的交流电流密度0～250A/m~2范围内,碳钢交流电腐蚀速度与干扰强度符合幂函数方程。交流干扰对极化曲线的影响表现为降低了表面反应电阻R_p,及降低阴、阳极Tafel斜率。由此解释了交流电腐蚀特征与规律,并探讨了交流电腐蚀机理。     

Enhanced enzyme activity and enantioselectivity of lipases in organic solvents by crown ethers and cyclodextrins

Lipases from Candida rugosa (CRL) and Pseudomonas cepacia (PCL) were co-lyophilized with cyclic oligoethers including four crown ethers and nine cyclodextrins (CyDs), and their transesterification activity and enantioselectivity in organic solvents were evaluated. The PCL co-lyophilized with each additive showed simultaneously enhanced enzyme activity and enantioselectivity when compared to the native lipase lyophilized from buffer alone; in contrast, such enhancement was not observed for the co-lyophilized CRL. Among the cyclic oligoethers examined, permethylated betaCyD (Me1.78betaCyD), as the most suitable additive, was used for the optimization of both the co-lyophilized PCL preparation and reaction conditions by determining the effects of varying the additive/lipase ratio, aqueous pH, the nature of organic solvents, and temperature. The initial rate determined for the transesterification between racemic 2,2-dimethyl-1,3-dioxolane-4-methanol and vinyl butyrate in diisopropyl ether at 30 degrees C increased by up to 17-fold and the enantioselectivity represented by E could be doubled. While there was an inverse correlation between temperature and enantioselectivity, with the Me1.78betaCyD-PCL co-lyophilizate, the reaction rate even at 0 degrees C was much higher than that at higher temperatures in the native PCL-catalyzed reaction. Hence, this method seems to be of practical use for the large-scale production of optically active compounds.     

涂层织物耐非水液体性测定方法

涂层织物耐非水液体性是涂层织物重要的性能指标之一。通过调研及实验，结合参照其他的测定方法，制定了本标准方法，将涂层织物试样浸渍于非水液体中，在室温下处理一定时间后，根据织物被侵蚀的情况评定分级。本法中的非水液体采用四氯乙烯、汽油、丙酮等七种试剂。本法分动态法和静态法两种。     

超顺磁性γ-Fe2O3纳米线的制备

通过硬质氧化法制备了孔径为150 nm,孔间距为230 nm的氧化铝模板。采用共沉淀法合成了具有超顺磁性的γ-Fe_2O_3纳米颗粒,其平均直径为8 nm。通过自下而上的组装工艺,将聚丙烯酸改性后带负电荷的γ-Fe_2O_3纳米颗粒和带正电荷的阳离子聚电解质聚合物在氧化铝模板的孔洞中组装成γ-Fe_2O_3纳米线阵列,并用SEM观察其形貌。采用振动样品磁强计(VSM)测得所制备的纳米线阵列的剩磁和矫顽力接近于零,说明该纳米线阵列具有超顺磁性。