Effects of 2-amino-5-ethylthio-1,3,4-thiadiazole on copper corrosion as a corrosion inhibitor in aerated acidic pickling solutions

Effects of 2-amino-5-ethylthio-1,3,4-thiadiazole (AETD) on copper corrosion as a corrosion inhibitor in an aerated acidic pickling solution of 0.50 M HCl have been investigated using gravimetric and electrochemical techniques. Weight losses of copper coupons in 0.50 M HCl measured after varied exposure periods of 2–12 h indicate that the addition of AETD significantly decreases the dissolution rate and the effect increases upon increasing its concentration. Results of potentiodynamic polarization experiments show a large decrease in cathodic, anodic, and corrosion currents due to the presence of the organic molecules. Potentiostatic current–time measurements at 200 mV versus Ag/AgCl for 120 min, scanning electron microscope (SEM), and energy dispersive X-ray (EDX) investigations also indicate that AETD greatly lowers the dissolution currents as a result of its strong adsorption onto the copper surface preventing it from being corroded easily. EIS measurements confirmed that the charge transfer resistance increases and mass transport decreases in the presence of AETD upon increasing its concentration.     

Room-temperature densification of MgO bulk ceramics with dispersed nitride phosphor particles

Wave conversion materials with high thermal conductivity are necessary for high-power semiconductor lighting. Ceramics have higher thermal conductivity than existing matrices such as resin or glass in which phosphor particles are dispersed. However, the high densification of ceramics generally requires high-temperature sintering, which degrades and alters the phosphor particles. In this study, we aimed to achieve the high densification of MgO ceramics at room temperature. Applying high hydrostatic pressure with water addition improved the sample packing ratio and promoted the formation of Mg(OH)₂. As a result, the relative density was ≥95%. Additionally, various nitride phosphor particles (CaAlSiN₃:Eu²⁺, β-SiAlON:Eu²⁺, and α-SiAlON:Eu²⁺) were dispersed in the MgO matrix at room temperature without degrading the luminescence property. The thermal conductivity of the obtained sample was about 8 W m^?1K^?1, 40 times higher than that of the epoxy matrix.     

几个含噻二唑环芳甲酰基脲的合成及生物活性

通过2-氨基-5-(3-吡啶基)-1,3,4-噻二唑与取代苯甲酰基异氰酸酯反应,得到相应的芳甲酰基脲:N-[5-(3-吡啶基)-1,3,4-噻二唑-2-基]-N′-(2-氯苯甲酰基)脲(Ⅲa)、N-[5-(3-吡啶基)-1,3,4-噻二唑-2-基]-N′-(2-溴苯甲酰基)脲(Ⅲb)、N-[5-(3-吡啶基)-1,3,4-噻二唑-2-基]-N′-(4-溴苯甲酰基)脲(Ⅲc)、N-[5-(3-吡啶基)-1,3,4-噻二唑-2-基]-N′-(2-甲基苯甲酰基)脲(Ⅲd)和N-[5-(3-吡啶基)-1,3,4-噻二唑-2-基]-N′-(4-三氟甲基苯甲酰基)脲(Ⅲe),收率分别为69.5%、67.2%、73.1%、66.8%和71.6%.产物的结构经红外光谱、核磁共振氢谱、质谱与元素分析表征.并对目标化合物进行了植物生长调节活性测试,初步的测试结果表明,目标化合物在10 mg/L表现出一定程度的生长素活性和较好的细胞分裂素活性,其中Ⅲc和Ⅲe的细胞分裂素活性超过40%.     

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s have been prepared by solution polycondensation reaction of different aromatic diamines having preformed 1,3,4-oxadiazole ring, such as 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole, 2,5-bis[p-(4-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2,5-bis[p-(3-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2-(4-dimethylaminophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole and 2-(4-fluorophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole, with an aromatic dianhydride incorporating ether linkages and hexafluoroisopropylidene group, namely 1,1,1,3,3,3-hexafluoro-2,2-bis-[(3,4-dicarboxyphenoxy)phenyl]-propane dianhydride. The polymers were easily soluble in polar organic solvents, such as N-methylpyrrolidinone, N,N-dimethylformamide, and pyridine, as well as in certain low boiling-point organic solvents, such as tetrahydrofuran and chloroform. Very thin coatings deposited onto silicon wafers exhibited smooth, pinhole-free surface in atomic force microscopy. The polymers showed high thermal stability with decomposition temperature being above 410 °C. They exhibited a glass transition in the temperature range of 183-217 °C, with reasonable interval between glass transition and decomposition temperature. Solutions of some polymers in N,N-dimethylformamide exhibited blue fluorescence, having maximum emission wavelength in the range of 411-424 nm.     

Metallo-homopolymer and metallo-copolymers containing light-emitting poly(fluorene/ethynylene/(terpyridyl)zinc(II)) backbones and 1,3,4-oxadiazole (OXD) pendants

A series of novel metallo-polymers containing light-emitting poly(fluorene/ethynylene/(terpyridyl)zinc(II)) backbones and electron-transporting 1,3,4-oxadiazole (OXD) pendants (attached to the C-9 position of fluorene by long alkyl spacers) were synthesized by self-assembled reactions. The integrated ratios of ¹H NMR spectra reveal a facile result to distinguish the well-defined main-chain metallo-polymeric structures which were constructed by different monomer ligand systems (i.e. single, double, and triple monomer ligands with various pendants). Furthermore, UV-vis and photoluminescence (PL) spectral titration experiments were carried out to verify the metallo-polymeric structures by varying the molar ratios of zinc(II) ions to monomers. As a result, the enhancement of thermal stability (T_d) and quantum yields were introduced by the metallo-polymerization, and their physical properties were mainly affected by the nature of the pendants. The photophysical properties of these metallo-polymers exhibited blue PL emissions (around 418 nm) with quantum yields of 34-53% (in DMF). In contrast to metallo-polymers containing alkyl pendants, the quantum yields were greatly enhanced by introducing 1,3,4-OXD pendants but reduced by carbazole (CAZ) pendants. Moreover, electroluminescent (EL) devices with these light-emitting metallo-polymers as emitters showed green EL emissions (around 550 nm) with turn-on voltages of 6.0-6.5 V, maximum efficiencies of 1.05-1.35 cd A⁻¹ (at 100 mA/cm⁻²), and maximum luminances of 2313-3550 cd/m² (around 15 V), respectively.     

Simple and green method for synthesis of symmetrical dialkyl disulfides and trisulfides from alkyl halides in water; PMOxT as a sulfur donor

An environmentally new, mild and efficient method has been developed for the synthesis of dialkyl disulfides and dialkyl trisulfides in aqueous conditions by a reaction between alkyl halides (and tosylate) and potassium-5-methyl-1,3,4-oxadiazole-2-thiolate (PMOxT) as a sulfur transfer reagent. The advantages of this method are that it occurs under mild reaction conditions, it is base free, it uses water as the solvent and it occurs in high yields. A variety of dialkyl disulfides and dialkyl trisulfides can be obtained in good to excellent yields up to 98%.     

1,3,4-噻二唑类液晶化合物的研究进展

综述了近年来1,3,4-噻二唑类液晶化合物的研究进展,该类化合物形成棒状液晶、楔形液晶、弓形液晶、Polycatenar液晶、盘状液晶的分子结构及其自组装形成的液晶相结构。介绍了分子中末端基团、烷基链数目、刚性核长度等结构常数对液晶自组装结构的的影响。与含氧的杂环类似物1,3,4-噁二唑液晶化合物相比,1,3,4-噻二唑类液晶化合物的液晶性、光电性等更加优越。液晶方面类比表明,它具有更好的液晶性质。     

新型共轭聚席夫碱蓝色发光材料的合成与性能

对硝基苯甲酸经酯化和肼解后制得对硝基苯甲酰肼,再与对硝基苯甲酰氯反应得到1,2-二(4-硝基苯甲酰基)肼,所得化合物通过环化和还原生成了2,5-二(4-氨基苯基)-1,3,4-噁二唑,然后在中性条件下与对苯二甲醛聚合得到一种主链含噁二唑单元和席夫碱单元的新型共聚体,利用元素分析、红外光谱、紫外光谱、热重分析和荧光光谱等对单体和聚合物进行检测.结果表明:1,3,4-噁二唑基团和席夫碱基团都是很好的生色团,对氧和热特别稳定;且两个基团相结合的聚合反应容易进行,所得聚合物的溶解性和热稳定性较好,并能发射较强的蓝色荧光,是一种具有发展前景的新型蓝色有机发光材料.     

浅析矿山工程造价失控原因与对策

针对当前矿山建设工程长期存在的工程造价不断提高、投资效果持续下降的问题,从矿山建设全过程的各个阶段,分析了矿山工程造价失控的主要原因,讨论了矿山工程造价控制的基本方法.     

Convergence analysis of geometrical multigrid methods for solving data-sparse boundary element equations

The convergence analysis of multigrid methods for boundary element equations arising from negative-order pseudo-differential operators is quite different from the usual finite element multigrid analysis for elliptic partial differential equations. In this paper, we study the convergence of geometrical multigrid methods for solving large-scale, data-sparse boundary element equations. In particular, we investigate multigrid methods for \(\mathcal{H}\)-matrices arising from the adaptive cross approximation to the single layer potential operator.