甲亢病人血清镁含量及其临床意义

用火焰原子吸收法测定了２０００例甲亢病人的血清镁含量及１２００例天津市正常人群血清镁含量，结果显示，甲亢病人血清镁含量显著低于正常人群，有显著统计意义（Ｐ〈０．０１）。提示：甲亢病人血清镁含量对甲亢病诊断及治疗过程的镁的摄入补充有重要的意义。     

一种CO2的矿化封存新方法

针对目前CO2矿化封存的研究现状,提出了一种新的CO2矿化封存方法:利用CO2和NH3反应生成三聚氰酸固体,并考察了温度、压力、反应物配比及有无催化剂对三聚氰酸收率的影响。当反应条件为在250℃,22MPa,NH3与CO2反应配比为1∶1.4,反应8h时,最高收率可达到68.3%。此项技术能够与现在工业成熟的富氧燃烧技术联用,实现对CO2的永久性封存,具有经济效益。     

Carbene tetrel-bonded complexes

An ab initio calculation has been carried for the carbene tetrel bonded complexes CH₃Y???CH₂ (Y = F, CN, NC, and NO₂), CH₃F???CZ₂ (Z = Cl and CH₃), XH₃F???CF₂ (X = C, Si, Ge, and Sn), SiF₄???CF₂, and XH₃F???NHC (N-heterocyclic carbene), where carbene is treated as a Lewis base and XH₃Y is a Lewis acid. Formation of the tetrel bond is mainly attributed to charge transfer from the lone pair on the C atom in the carbene toward the σ* X–Y orbital and also the σ* X–H one in the strong tetrel bond. The carbene tetrel bond is strengthened/weakened by the electron-withdrawing group in the tetrel donor/acceptor and enhanced by the methyl group in C(CH₃)₂. NHC forms a stronger carbene tetrel bond in XH₃F???NHC (X = Si, Ge, and Sn) where it exceeds that of the majority of H-bonds. Interestingly, the tetrel bond becomes stronger in the order of X = C < Ge < Sn < Si in XH₃F???NHC and the largest interaction energy occurs in SiH₃F???NHC, amounting to ?103 kJ/mol. The carbene tetrel bond can be strengthened by cooperative effect with the N???M interaction in trimers H₂C???CH₃CN???M (M = CH₃CN, HCN, ICN, SbH₂F, LiCN, and BeH₂) and has doubled in H₂C???CH₃CN???BeH₂.

     

单个激光二极管对称侧向抽运的固体激光器

采用一种半导体激光器侧向抽运的固体激光器新结构，可将一个半导体激光器的输出光分成四部分，从四面对称耦合到激光棒中，从而实现比较均匀的抽运。模拟计算了这种对称抽运结构中激光棒对侧面抽运光的吸收过程，得到了激光棒介质的吸收系数和直径等参量对激光棒内抽运光能量分布均匀性和能量吸收率的影响规律，并在此基础上对相关参量进行了优化。这种方案结构简单紧凑，很容易获得高光束质量的高功率固体激光输出。采用这种抽运结构制成了新颖的激光头，初步实验结果良好，表明该结构确实可行。     

小波变换传递误差、尺度、加权量化对分层树剖分编码图象压缩质量影响的研究

详细研究了小波变换传递误差、尺度、快速Mallat算法加权量化对分层树剖分(SPIHT)编码图象压缩质量的影响,并给出了基于VC++的仿真结果,结果表明,小波变换尺度对图象压缩编码效果有明显的影响,通常要在大于4的尺度上作图象压缩编码才可以得到较好的压缩效果,不同的边界延拓,不同尺度的取整重构、加权量化对图象压缩效果的影响是不同的,恰当选取加权量化步长能达到更好的图象压缩效果,一般而言,同一尺度下随加权量化步长的增加,压缩效果变差.     

Effects of weathering and rainfall conditions on the release of SiO<Subscript>2</Subscript>, Ag,and TiO<Subscript>2</Subscript> engineered nanoparticles from paints

Previous studies on the fate of engineered nanoparticles (ENPs) incorporated in paints mainly focused on the release of the particles as affected by a limited number of factors or monitoring their release from natural sources. In this study, the effects of four factors (i.e., weathering duration, water pH, rainfall duration and intensity) were investigated on the release of SiO₂-ENPs, Ag-ENPs, and TiO₂-ENPs from paints applied on panels. The static water immersion test showed that the concentrations of studied particles all increased with weathering duration. At low and high pH, SiO₂-ENPs and Ag-ENPs showed a higher release, while the release of TiO₂-ENPs was relatively high at low pH. With increased simulated rainfall duration, the concentration released decreased for Si, and the opposite was observed for Ag, while no obvious correlation was noted for Ti. With greater rainfall intensity, there was increasing release of all particles. In total, the releases of Ag-ENPs and TiO₂-ENPs were extremely low and within the level of 21.32–42.16 μg L^?1and 0.6–2.3 μg L^?1, respectively, while the values for SiO₂-ENPs were in the range of 7.5–12 mg L^?1. Additionally, microscopic results highlighted that SiO₂-ENPs were mainly released in the form of agglomerates, and only a small fraction was below 0.1 μm. Considering these influence factors together, conclusions may be made that weathering time and rainfall duration are more important in controlling release than water pH.

Open image in new window

Graphical abstract ?

     

千瓦级半导体抽运的固体热容板条激光器

报道了千瓦级激光二极管面阵抽运固体热容激光器的理论与实验研究,分别采用Nd∶YAG单板条和双板条串接的热容激光器,利用热容激光器的理论计算模型计算了在一定的工作时间内激光输出特性,并进行了实验验证。实验中采用的晶体尺寸均为59mm×40mm×4.5mm,对单板条进行抽运时平均功率大约为5.6kW,双板条串接时为11.2kW,重复频率为1kHz,占空比为20%。实验中观察了1s的工作时间内脉冲能量输出的波动情况,单板条时单脉冲能量输出最大为1.3J,在1 s后单脉冲能量输出下降到开始的70%左右,而双板条串接时单脉冲能量输出最大为2.06J,在1s后单脉冲能量输出下降到开始的50%左右,对单块晶体采用通水冷却的准热容热管理模式能有效地降低其热效应。     

Yb∶YAG薄片激光介质的温度效应

研究了Yb∶YAG薄片激光器中影响激光介质温度的几个因素。理论和实验均表明减薄Yb∶YAG片并增加抽运光被YAG片吸收的次数 ,是降低激光介质温度、提高激光器输出功率和效率的有效途径。用 0 .35mm厚的Yb∶YAG薄片获得 15 .9W的 1.0 3μm激光输出 ,斜率效率超过 40 %。     

Formation of uniform ferrocenyl-terminated monolayer covalently bonded to Si using reaction of hydrogen-terminated Si(111) surface with vinylferrocene/n-decane solution by visible-light excitation

Electrochemically active self-assembled monolayers (SAM) have been successfully fabricated with atomic-scale uniformity on a silicon (Si)(111) surface by immobilizing vinylferrocene (VFC) molecules through Si-C covalent bonds. The reaction of VFC with the hydrogen-terminated Si (H-Si)(111) surface was photochemically promoted by irradiation of visible light on a H-Si(111) substrate immersed in n-decane solution of VFC. We found that aggregation and polymerization of VFC was avoided when n-decane was used as a solvent. Voltammetric quantification revealed that the surface density of ferrocenyl groups was 1.4×10(-10) mol cm(-2), i.e., 11% in substitution rate of Si-H bond. VFC-SAMs were then formed by the optimized preparation method on n-type and p-type Si wafers. VFC-SAM on n-type Si showed positive photo-responsivity, while VFC-SAM on p-type Si showed negative photo-responsivity.     

2-芳基-4-三氟甲基喹唑啉衍生物的合成及抗肿瘤活性研究

为寻找高效低毒的含三氟甲基取代的喹唑啉类新型抗肿瘤活性化合物,以2-硝基-5-氯苯甲酸为原料,通过水解、还原、偶联、环合、三氟甲基加成消除等反应,合成了14个2-芳基-4-三氟甲基喹唑啉衍生物,并通过¹H NMR、¹³C NMR、¹⁹F NMR等进行了结构确证。采用MTT法评价了目标化合物对PC3(前列腺癌细胞)、LNCaP(前列腺癌细胞)、K562(人慢性髓系白血病细胞)、HeLa(宫颈癌细胞)和A549(人肺癌细胞)等肿瘤细胞株的生长抑制活性。结果显示,在5μmol/L浓度下,部分目标化合物对上述5种肿瘤细胞均具有较好的生长抑制活性,其中,化合物8c、13e对LNCaP细胞的IC₅₀(半数抑制浓度)分别为2.9和1.9μmol/L,值得进一步深入研究。