SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS XXX III. SELECTIVITIES OF ALKALI METAL IONS ON TIN(IV) ANTIMONATE CATION-EXCHANGER PREPARED AT DIFFERENT CONDITIONS

ABSTRACT

A tin(IV) antimonate(SnSbA) cation exchanger has been synthesized under different conditions; changes in the concentration, the molar ratio of Sb/Sn in the starting solution, and hydrolysis temperature. The products obtained were characterized by powdered X-ray diffraction and thermal analysis, and infrared spectra. The pH titration curves on SnSbA showed apparently mono-basic acid, but can be expected to the presence of the number of the functional groups with overlapping different pKa values. The increased acidities were observed with increasing the molar ratio (Sb/Sn) in the exchanger. The equilibrium distribution coefficients were determined at micro-amount of alkali metal ions in the hydrochloric acid solution. The SnSbA showed an unusual selectivity for alkali metal ions compared to cation exchange resins and other inorganic ion-exchangers.

The selectivity sequence shows; Na⁺ < K⁺ < Rb⁺ < Cs⁺ < Li⁺

An extremely high selectivity of lithium ions was found on the SnSbA hydrolyzed at relatively high temperature and with high Sb/Sn molar ratio     

SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS XXXVI. SYNTHESIS OF CRYPTOMELANE-TYPE HYDROUS MANGANESE DIOXIDE AS AN ION-EXCHANGE MATERIAL AND THEIR ION-EXCHANGE SELECTIVITIES TOWARDS ALKALI AND ALKALINE EARTH METAL IONS

Abstract

Hydrous manganese dioxide in a cryptomelane-type showed an excellent ion-exchange selectivity for K⁺, Rb⁺and Ba²⁺ ions having the effective ionic radii of about 1.4 Å. Log-log plots of distribution coefficients for alkali and alkaline earth metal ions vs. [HNO₃] yielded a straight line with a slope of ?1 and ?2, respectively, indicating the “ideal” ion-exchange mechanism. The stoichiometry of ion-exchange reactions was also established for the uptake of macro-amounts of alkali metal ions in nitrate media.     

Soft‐Switching Interleaved PFC Converter with Lossless Snubber

This paper describes a soft‐switching interleaved power factor correction (PFC) converter with a lossless snubber. AC–DC converters require a unity input power factor characteristic with highly efficient operation to prevent the inflow of harmonic current to the power source. The proposed PFC converter improves the input current ripple with interleave control. The converter realizes a high efficiency by the soft‐switching operation of all switching devices without a large auxiliary resonant circuit. This paper introduces the soft‐switching operation of the converter. In order to confirm the validity of the proposed converter, experiments with a prototype of the PFC converter have been performed. The experimental results indicate that the proposed converter can realize the soft‐switching operation of all switching devices, a reduction in the input current ripple, a unity power factor of 98% or more, a sinusoidal input current, and constant output voltage control. The efficiency of the proposed PFC converter with a lossless snubber is higher than that without the lossless snubber. The results presented in this paper confirm the validity of the proposed converter.     

Implantable cardioverter defibrillator in maintenance hemodialysis patients with ventricular tachyarrhythmias: A single-center experience

Patients with hemodialysis (HD) are at risk of death due to cardiac arrhythmias, worsening congestive heart failure (CHF), and noncardiac causes. This study reviews our experience with the use of implantable cardioverter defibrillators (ICDs) in patients with ventricular tachycardia who are under maintenance HD. We retrospectively reviewed 71 consecutive patients who underwent an ICD implantation in our hospital. There were 11 patients under maintenance HD and 60 patients without HD. The group of patients with HD (HD group) was compared with the patients without HD (control group). The mean follow-up period was 30±9 vs. 39±4 months in the HD group vs. the control group, respectively. Among these patients, 6 in the HD group and 26 in the control group received appropriate ICD therapies. There was no difference in appropriate ICD therapy, time to the first therapy, and electrical storm between the 2 groups. In the HD group, 1 patient underwent surgical removal of the ICD system due to infective endocarditis. There were 5 deaths in the HD group (4 from CHF) and 8 deaths in the control group (4 from CHF). There were no sudden cardiac deaths or arrhythmic deaths in both groups of patients during the follow-up period. However, the overall death rate was significantly higher in the HD group (P<0.01). In HD patients, ICD therapy prevented arrhythmic death, but their rate of nonarrhythmic adverse outcomes was high. This risk-benefit association should be considered before implantation of the device.     

复杂局域结构的STEM非相干成像测定

Nano-or atomic-scale microstructural control has become a key technique to develop superior functional materials,and the success of such project largely relies upon a precise characterization of local atomic/electronic structures.Understanding atomistic origins of nanomaterial's properties will lead to establishing structureproperty relationships,which have been one of the major challenging issues in materials science.     

Reversible Optical Change of Amorphous Red Phosphorus in Reduced Phosphate Glasses

Amorphous red phosphorus formed in reduced phosphate glasses was found to show a photodarkening effect by illuminating the glasses with light approximately equivalent to its absorption edge; the optical transmission edge shifts toward longer wavelengths on illumination, and then a distinct deepening of the reddish color is observable visually. The photo-darkened specimen recovers its original transmission when it is heated at 300° to 350°C. This darkening-restoring process is confirmed to be reversible by repeated illumination and heating. Transmission measurements over a range of elevated temperatures suggest that this optical characteristic of red phosphorus is unique to its amorphous state.     

Photosensitive Mechanism of Dopant-Free, Ultraviolet-Sensitive Calcium Aluminate Glasses

Calcium aluminate glasses show high sensitivity to ultraviolet radiation without the doping of optically active components. A mechanism is proposed to account for their photosensitivity on the basis of the result that the cause of UV-induced coloring is the emergence of two kinds of paramagnetic centers, an aluminum-oxygen hole center (Al-OHC) and an ozonide (O^-₃). In this model, a peroxy linkage connecting tetrahedrally coordinated Al³⁺s and a physically dissolved O₂ molecule are assumed to be present in the glasses as structural defects. On exposure to UV rays, the peroxy linkage homolvtically dissociates into a pair of A1-OHC's by absorbing UV quanta and one of the two resulting A1-OHC's combines with a nearby O₂ to form an ozonide. Experimental evidences substantiating the mechanism are also reported.     

Photosensitive Characteristics of Dopant-Free, Ultraviolet-Sensitive Calcium Aluminate Glasses

Calcium aluminate glasses show high sensitivity to ultraviolet radiation without the doping of optically active components. In this paper, photosensitive characteristics and the cause of UV-induced coloring were investigated for these glasses. Ultraviolet rays below 270 nm were effective for inducing the coloring. The most effective wavelength agreed with that of the apparent absorption edge. In the ternary system with SiO₂ or GeO₂, the sensitivity was monotonically reduced with the amount of the third component and almost vanished for the compositions containing 40 mol%. On the basis of the establishment of a close correlation between two optical absorption bands and two electron spin resonance signals induced by UV illumination, the UV-induced coloring was concluded to be due to the emergence of an aluminum-oxygen hole center (Al-OHC) and an ozonide (O₃^-).     

无刷直流电动机极槽配合及低噪音驱动技术

通过理论分析、有限元仿真和实验研究,提出薄型化、高输出、宽调速无刷直流电动机的设计分析及低噪音驱动的相关技术.采用本文的方法可获得高的额定输出功率、高功率密度和宽的调速范围.利用基于霍尔信号的高分辨率转子位置推测法及基于超前角控制的转矩补偿法正弦波低噪音驱动新技术,可明显降低噪音.