Two Four‐Coordinate and Seven‐Coordinate CoII Complexes Based on the Bidentate Ligand 1, 8‐Naphthyridine Showing Slow Magnetic Relaxation Behavior

For a long time, the cobalt(II) complex ([Co(napy)₄](ClO₄)₂) (napy=1, 8‐naphthyridine) has been considered as an eight‐coordinate complex without any structural proof. After careful considerations, two complexes [Co(napy)₂Cl₂] ( 1 ) and [Co(napy)₄](ClO₄)₂ ( 2 ) based on the bidentate ligand napy were synthesized and structurally characterized. X‐ray single‐crystal structural determination showed that the cobalt(II) center in [Co(napy)₂Cl₂] ( 1 ) is four‐coordinate with a tetrahedral geometry (T_d), while [Co(napy)₄](ClO₄)₂ ( 2 ) is seven‐coordinate rather than eight‐coordinate with a capped trigonal prism geometry (C_2v). Direct‐current (dc) magnetic data revealed that complexes 1 and 2 possess positive zero‐field splitting (ZFS) parameters of 11.08 and 25.30 cm^?1, respectively, with easy‐plane magnetic anisotropy. Alternating current(ac) susceptibility measurements revealed that both complexes showed slow magnetic relaxation behaviour. Theoretical calculations demonstrated that the presence of easy‐plane magnetic anisotropy (D>0) for complexes 1 and 2 is in agreement with the experimental data. Furthermore, these results pave the way to obtain four‐coordinate and seven‐coordinate cobalt(II) single‐ion magnets (SIMs) by using a bidentate ligand.     

药物流产后宫内残留物的腹部超声检测及其对清宫术时机的指导作用

本文对药物流产后宫内残留物的腹部超声检测及其对清宫术时机的指导作用进行了探讨。研究对象为2017年4月~2018年10月我院妇科收治的164例药物流产后宫内组织残留患者,所有患者均行经腹彩色多普勒超声检查,观察宫腔内异常回声团和宫内血流信号及频谱,并记录患者治疗情况和病理结果。依据患者保守治疗成功或转归清宫术分为成功组和转归组,采用多因素Logistic回归方程分析对保守治疗失败转归清宫术有影响的因素。结果显示,164例患者中,79例(48.17%)患者超声检查显示存在滋养血流,其中47例(59.49%)患者采取了清宫术治疗,其余32例(40.51%)患者保守治疗失败转归清宫术治疗;85例(51.83%)患者超声检查显示无滋养血流,其中73例(85.88%)采取保守治疗成功,其余12例(14.12%)患者保守治疗失败转归清宫术;成功组(n=73)和转归组(n=44)患者在就诊时阴道出血时间、阴道出血持续时间、流产次数、宫内残留物大小、滋养血流信号检出率等方面的比较,差异均具有统计学意义(P<0.05);多因素Logistic回归方程分析结果显示,就诊时阴道出血时间、残留物大小、流产次数、超声检查存在滋养血流均为保守治疗转归清宫术的独立影响因素(P<0.05)。本文结果证实,腹部超声检测显示宫腔内异常回声团块存在滋养血流信号,可作为药物流产不全患者行清宫术治疗的手术指征,有利于改善患者预后。     

Cellulose Nanocrystal Elastomers with Reversible Visible Color

Responsive photonic crystals have potential applications in mechanical sensors and soft displays; however, new materials are constantly desired to provide new innovations and improve on existing technologies. To address this, we report stretchable chiral nematic cellulose nanocrystal (CNC) elastomer composites that exhibit reversible visible color upon the application of mechanical stress. When stretched (or compressed) the colorless materials maintain their chiral nematic structure but the helical pitch is reduced into the visible region, resulting in coloration of the CNC‐elastomer composite. By increasing the percentage elongation of the material (ca. 50–300 %), the structural color can be tuned from red to blue. The color of the materials was characterized by reflectance optical microscopy and reflectance circular dichroism to confirm the wavelength and polarization of the reflected light. We also probed the mechanism of the structural color using 2D‐X‐ray diffraction. Finally, by either water‐patterning the starting CNC film, or by forming a CNC film with gradient color, through masked evaporation, we were able to prepare encoded stretchable chiral nematic CNC‐elastomers.     

运用“颜色识别器”软件探究常见净水剂的净水原理*

盐类水解的应用中铝盐和铁盐的净水作用涉及胶体的生成与吸附聚沉,是一个综合且复杂的化学问题,为发展学生化学学科素养,利用“颜色识别器”软件中色密度(V)值与黄土壤浊液中土壤含量的半定量关系,建构了一种基于课堂教学的快速定量测定工业净水剂净水效果的实验方法,为化学课堂教学中关于盐类水解的具体应用提供了真实情境和探究案例。     

High pressure Raman spectra of d-threonine crystal

Raman spectra of d-threonine crystal were recorded for pressures up to 8.5 GPa. Modifications in the lattice modes indicate that the crystal undergoes two structural phase transitions, the first in the 1.9–2.4 GPa pressure range and the second in the 5.1–6.0 GPa pressure range. Splitting of modes and changes in the intensity of several bands suggest a conformational reorientation of the molecule in the crystal framework between 3.5 and 4.3 GPa. We discussed ours results by comparing with previous high-pressure investigation on l-conformer.     

TG and Flammability Studies on Polymer Blends Containing Acrylonitrile–butadiene–styrene and Chlorinated Poly(vinyl Chloride)

The effects which an iron(III) based smoke suppressing compound have on the thermal stability of some acrylonitrile–butadiene–styrene/chlorinated poly(vinyl chloride) (ABS/CPVC) polymer blends have been investigated. Thermogravimetric analysis (TG) experiments have shown that there are three distinctive stages occurring during the thermal breakdown of these blends both when the iron compound is absent and present in the polymer formulations. The most important effect which the iron compound has when it is present in these blends is to modify the decomposition chemistry which takes place and the effect becomes more pronounced as the concentration of CPVC present in the blends increases. Other important effects are that the iron compound stabilises the blends so that mass loss is significantly reduced (by up to 50% in some cases) and the onset temperature of decomposition is raised. Flammability data generated during earlier work is supported by the TG results obtained in this work especially in the important area of smoke formation and suppression. This revised version was published online in August 2006 with corrections to the Cover Date.     

Estimation of thermal contact resistance and thermally induced optical effects in single-coated optical fibers

In this study, a conjugate gradient method based on an inverse algorithm is applied to estimate the unknown time-dependent thermal contact resistance in a single-coated optical fiber, which is subjected to transient thermal loading. While knowing the temperature history at the measuring position, no prior information is needed on the functional form of the unknown contact resistance. The temperature data obtained from the direct problem are used to simulate the temperature measurement. The influence of measurement errors, initial guess values, and measurement locations upon the precision of the estimated results is also investigated. Results show that an excellent estimation on the time-dependent thermal contact resistance, temperature distributions, thermally induced microbending loss, and refractive index changes can be obtained for the case considered in this study.     

基于多光谱和sRGB空间的自然植物色的重现

多光谱成像技术在颜色科学方面的应用主要在于准确的记录和复制拍摄场景的颜色信息。针对目前基于光谱的颜色重现设备昂贵、复杂和实现起来困难的问题,提出了物体颜色从反射光谱空间向sRGB颜色空间变换的方案。在遵循sRGB标准的设备上重现了D65光源下的218种自然植物颜色,所显示的颜色与植物反射光谱实物对应的名称一致。对8个自然植物在9种不同光源下和在sRGB空间下的颜色进行了预测显示。所提出的方案对在网络环境下实现相同实物在不同照明环境下的场景显示提供了可行的途径。     

Dual-beam laser analyzer for inhomogeneities in active regions of multielement photodetectors

We describe equipment and a procedure for measuring inhomogeneities in active regions of solar cells, photoelectric transducers, and multielement photodetectors, based on a computer-controlled dual-beam laser scanner including a Pentium III personal computer, an HP-34401A digital multimeter with RS-232 serial interface;, a platform movable along the Y coordinate with the sample multielement photodetector to be tested and a microprobe device for picking up the photocurrents, an optical head with laser photodiodes in the visible (λ₁ = 0.68 μm) and IR (λ₂ = 0.82 μm) ranges scanning along the X coordinate, and a control unit for focusing the laser beams λ₁, λ₂, stabilizing the laser radiation power, and controlling the step motors for the X,Y coordinates. The equipment and procedure enable laser scanning of sample multielement photodetectors, with external dimensions 10 × 10 μm2 to 150 × 150 mm², along the X, Y coordinates at a maximum rate of 100 mm/sec; minimum radiation power of the laser diodes, 10 mW; range of laser beam diameters, 2–50 μm; range of scanning steps along the X, Y coordinates, 5–100 μm; current sensitivity 1·10⁻⁸ A, voltage sensitivity 1·10⁻⁷ V; measurement and analysis accuracy at least 0.5%; storage of color plots of the inhomogeneities in the active regions of the multielement photodetectors on the hard disk of the personal computer, with output of analysis results to a monitor and color printer, 32 color gradations. Software written in Delphi 7.0. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 277–280, March–April, 2006.