Enhanced transformation of triclosan by laccase in the presence of redox mediators

Triclosan (TCS), an antimicrobial agent, is an emerging and persistent environmental pollutant that is often found as a contaminant in surface waters and sediments; hence, knowledge of its degradability is important. In this study we investigated laccase-mediated TCS transformation and detoxification, using laccase (from the fungus Ganoderma lucidum) in the presence and absence of redox mediators. Transformation products were identified using HPLC, ESI-MS and GC-MS, and transformation mechanisms were proposed. In the absence of redox mediator, 56.5% TCS removal was observed within 24 h, concomitant with formation of new products with molecular weights greater than that of TCS. These products were dimers and trimers of TCS, as confirmed by ESI-MS analysis. Among the various mediators tested, 1-hydroxybenzotriazole (HBT) and syringaldehyde (SYD) significantly enhanced TCS transformation (∼90%). The presence of these mediators resulted in products with lower molecular weights than TCS, including 2,4-dichlorophenol (2,4-DCP; confirmed by GC-MS) and dechlorinated forms of 2,4-DCP. When SYD was used as the mediator, dechlorination resulted in 2-chlorohydroquinone (2-CHQ). Bacterial growth inhibition studies revealed that laccase-mediated transformation of TCS effectively decreased its toxicity, with ultimate conversion to less toxic or nontoxic products. Our results confirmed the involvement of two mechanisms of laccase-catalyzed TCS removal: (i) oligomerization in the absence of redox mediators, and (ii) ether bond cleavage followed by dechlorination in the presence of redox mediators. These results suggest that laccase in combination with natural redox mediator systems may be a useful strategy for the detoxification and elimination of TCS from aqueous systems.     

栅侧壁隔离层对45nm NOR闪存栅极干扰的影响

为了研究侧壁隔离层对闪存器件可靠性的影响,分别制备了Si3N4和SiO2-Si3N4-SiO2-Si3N4 (ONON)复合层作为栅侧壁隔离层的45 nm或非闪存(NOR flash)器件,对编程后、循环擦写后的闪存器进行栅极干扰的测试,讨论了不同栅侧壁隔离层对栅极干扰的影响.结果表明,虽然纯氧化硅隔离层可减少NOR自对准接触孔(SAC)刻蚀时对侧壁隔离层的损伤,但其在栅极干扰时在氧化物-氮化物-氧化物(ONO)处有更高的电场,从而在栅干扰后阈值电压变化较大,且由于在擦写操作过程中会陷入电荷,这些电荷在大的栅极电压和长时间的栅干扰作用下均会对闪存器的可靠性产生负面的影响.ONON隔离层的闪存器无可靠性失效.因此以ONON作为侧壁隔离层比以纯氮化硅作为侧壁隔离层的闪存器件具有更好的栅干扰性能.     

HPLC法测定复方托吡卡胺滴眼液中苯扎氯铵的含量

目的：建立超高效液相色谱法测定复方托吡卡胺滴眼液中苯扎氯铵的含量测定方法。方法：色谱柱为Alltech Alltima -CN（250cm ×4．6mm ,5μm）,流动相为0．1mol?L -1醋酸钠溶液（用冰醋酸调节pH值至5．0）-乙腈（60：40）,检测波长254nm ,流速为2．0ml?min -1,柱温30℃,进样体积50μL。结果：苯扎氯铵在0．02至0．5mg?mL -1浓度范围内线性关系良好（r＝0．9999）;平均回收率为98．91％,RSD＝0．44％（n＝9）。结论：该方法准确、简便、快速、可靠,能有效控制复方托吡卡胺滴眼液中苯扎氯铵的含量。     

环氧树脂对环氧模塑料(EMC)的性能影响分析

在环氧模塑料中,环氧树脂是环氧模塑料的基体树脂,也是环氧模塑料的主要原材料,起着将其他组分交联结合到一起的重要作用。环氧树脂作为环氧模塑料的胶粘剂,具有粘合性高、固化收缩率小、耐化学介质稳定性好、电绝缘性优良、工艺性能良好等特点。因此环氧树脂类型的选择及其性能对环氧模塑料的性能都有很大的影响。文章简单介绍了环氧树脂的分类、结构、作用及特点,主要探讨了不同结构环氧树脂对环氧模塑料的粘接性、稳定性、收缩率、电性能及机械性能等的影响。     

基于复合预测误差差值和互补嵌入的可逆数据隐藏

提出一种基于分块复合预测的误差差值和互补嵌入的彩色图像可逆数据隐藏算法。利用色彩分量之间的相关性和预测误差之间的关系减小差值,以增加差值直方图的峰值。采用双重嵌入方法提高嵌入容量,两次嵌入过程中像素值沿相反的方向扩展,部分像素值扩展量相互抵消,在图像分块的基础上选择最佳的预测方式组合,以增加扩展量抵消的机会,从而减小二次嵌入时图像质量的下降幅度。实验结果表明,本文算法在保证图像质量的同时大幅提高嵌入容量,算法的整体性能比其它同类算法更高。     

Effect of multiple reflows on interfacial reaction and shear strength of Sn-Ag electroplated solder bumps for flip chip package

The effect of displacement rate and intermetallic compound (IMC) growth on the shear strength of electroplated Sn-2.5Ag (in wt.%) flip chip solder with Cu under-bump metallization (UBM) were investigated after multiple reflows. Cu₆Sn₅ IMC was formed at the interface after one reflow. After five reflows, two different IMC layers, consisting of a scallop-shaped Cu₆Sn₅ phase and a planar Cu₃Sn phase, and their thicknesses increased with increasing reflow number up to 10. The shear strengths peaked after four reflows, and then decreased with increasing reflow number. Increasing displacement rate increased the shear force. The tendency toward brittle fracture characteristics was intensified with increasing displacement rate and reflow number.     

三官能度NIMMO-THF共聚醚含能粘合剂的合成与固化

以三羟甲基丙烷(TMP)为引发剂,三氟化硼·乙醚络合物为催化剂,使四氢呋喃(THF)和3?硝酸酯甲基?3?甲基氧杂环丁烷(NIMMO)开环聚合,得到了三官能度的3?硝酸酯甲基?3?甲基氧杂环丁烷与四氢呋喃的无规共聚醚(三官能度NIMMO?THF共聚醚)含能粘合剂。采用红外光谱、核磁共振和差示扫描量热(DSC)对产物进行了表征。以六亚甲基二异氰酸酯(HDI)为固化剂固化合成的三官能度NIMMO?THF共聚醚含能粘合剂,按照六亚甲基二异氰酸酯的异氰酸根与三官能度NIMMO?THF共聚醚含能粘合剂羟基的物质的量之比(R值)分别为0.8、0.9、1.0、1.1和1.2制备出了弹性体,研究了弹性体的力学性能和热性能。结果表明,10℃·min-1时,三官能度NIMMO?THF共聚醚含能粘合剂DSC的分解峰温在216℃;当R值为1.1时,弹性体拉伸强度最高,为1.32 MPa,10℃·min-1时,弹性体DSC的分解峰温为203℃。     

空空导弹制导技术发展趋势

介绍了应用在空空导弹的激光制导、红外复合制导、毫米波成像制导、多模复合制导技术的发展趋势,同时介绍了视觉仿生成像、网络中心等制导新技术。应用新的制导技术,可显著提高空空导弹的制导精度,提高武器的作战效能。     

新型钝感含能增塑剂3-硝基呋咱-4-甲醚的合成与性能研究

以氰基乙酸乙酯为起始原料,用一锅法先行合成了前体化合物3-氨基呋咱-4-羧酸(AFCA),产率46％.再通过NaBH4/ZnCl2还原体系和H2O2/H2SO4氧化体系先后得到了3-氨基呋咱-4-甲醇(AFMA)及3-硝基呋咱-4-甲醇(NFMA).用SOCl2将NFMA氯化,得到3-硝基-4-氯甲基呋咱(NFCM),...     

Microstructure and shear strength of Sn37Pb/Cu solder joints subjected to isothermal aging

The effects of isothermal aging on the microstructure and shear strength of Sn37Pb/Cu solder joints were investigated. Single-lap shear solder joints of eutectic Sn37Pb solder were aged for 1–10 days at 120 °C and 170 °C, respectively, and then loaded to failure in shear with a constant loading speed of 5 × 10⁻³ mm/s. The growth of the interfacial Cu–Sn intermetallic compounds (IMC) layer (Cu₆Sn₅ + Cu₃Sn) of Sn37Pb/Cu solder joints subjected to isothermal aging exhibited a linear function of the square root of aging time, indicating that the formation of Cu–Sn IMC was mainly controlled by the diffusion mechanism. And the diffusion coefficient (D) values of IMC layer were 1.07 × 10⁻¹⁷ and 3.72 × 10⁻¹⁷ m²/s for aged solder joints at 120 °C and 170 °C, respectively. Shear tests results revealed that as-reflowed solder joint had better shear strength than the aged solder joints and the shear strength of all aged solder joints decreased with increasing aging time. The presence of elongated dimple-like structures on the fracture surfaces of these as-reflowed or aged for short time solder joints were indicative of a ductile failure mode. As aging time further increased, the solder joints fractured in the mixed solder/IMC mode at the solder/IMC interface.