Modification of Bentonite and Its Application in Antimicrobial Material

This paper aims to expand the application scope of bentonite. The structure of bentonite and the purification and pretreatment methods performed before its modification were reviewed. The modification of bentonite and its application in antibacterial materials were emphasized.     

Furnace smelting and extractive metallurgy of red mud: Recovery of TiO2, Al2O3 and pig iron

Turkish red mud (bauxite waste) has been mixed with dolomite and coke, pelletized and sintered at 1100°C, and finally smelted at 1550°C to produce pig iron and a slag. The slag was leached with 30% H₂SO₄ at 90°C. The leachate was diluted, ferric iron was reduced with SO₂, and extracted with 5% D2EHPA solution in kerosene. Silica and Al₂O₃ were recovered from the remaining aqueous solution, while the organic extract was stripped with 10% Na₂CO₃ solution, finally hydrolysed and calcined to produce pigment-grade TiO₂. The titanium recovery efficiency on the basis of slag weight was 84·7%. The extractive separation of titanium from both valencies of iron was investigated as a function of pH and time. A stoichiometric flowsheet for the whole process has been developed. ©1997 SCI     

音频记录磁带恢复技术在抢救文艺有声资料项目中的应用

老化音频资料磁带有必要进行物理和化学方法的修复处理,以利在进行资料转储和重建时能采集到更好质量的信号.利用本项目技术处理后的录音资料磁带,其回放效果是向原录状态回归的,是本原的和原始状态的,处理过程中未加入任何用以改善放音音质的信号成分.相对于音频信号数字补偿方法,其输出结果具有更好的主观接受度和客观真实度.     

Ultrasensitive detection and characterization of posttranslational modifications using surface-enhanced Raman spectroscopy

Posttranslational modification (PTM) of proteins is likely to be the most common mechanism of altering the expression of genetic information. It is essential to characterize PTMs to establish a complete understanding of the activities of proteins. Here, we present a sensitive detection method using surface-enhanced Raman spectroscopy (SERS) that can detect PTMs from as little as zeptomoles of peptide. We demonstrate, using model peptides, the ability of SERS to detect a variety of protein modifications, such as acetylation, trimethylation, phosphorylation, and ubiquitination. In addition, we show the capability to obtain positional information for modifications such as trimethylation and phosphorylation using SERS and wavelet decomposition data analysis techniques. We further show that it is possible to apply SERS to detect PTMs from biological samples such as histones. We envision that this detection method might be a valuable technique that is complementary to mass spectrometry in obtaining orthogonal chemical and modification-specific information from biological samples at sensitive levels.     

Effects of frequency-dependent attenuation and velocity dispersion on in vitro ultrasound velocity measurements in intact human femur specimens

Numerous studies have shown that ultrasonic velocity measured in bone provides a good assessment of osteoporotic fracture risk. However, a lack of standardization of signal processing techniques used to compute the speed of sound (SOS) complicates the comparison between data obtained with different commercial devices. In this study, 38 intact femurs were tested using a through-transmission technique and SOS determined using different techniques. The resulting difference in measured SOS was determined as functions of the attenuation and the velocity dispersion. A numerical simulation was used to explain how attenuation and dispersion impact two different SOS measurements (group velocity, velocity based on the first zero crossing of the signal). A new method aimed at compensating for attenuation was devised and led to a significant reduction in the difference between SOS obtained with both signal processing techniques. A comparison between SOS and X-ray density measurements indicated that the best correlation was reached for SOS based on the first zero crossing apparently because it used a marker located in the early part of the signal and was less sensitive to multipath interference. The conclusion is that first zero crossing velocity may be preferred to group velocity for ultrasonic assessment at this potential fracture site.     

Influence of annealing temperature and oxygen atmosphere on the optical and photoluminescence properties of BaTiO3 amorphous thin films prepared by sol–gel method

Homogeneous and transparent BaTiO₃ thin films were prepared by sol–gel dip coating method. The prepared BaTiO₃ thin films were annealed in air and O₂ atmosphere at different temperatures. The annealed BaTiO₃ thin films were amorphous in nature. Scanning electron microscopy (SEM) revealed the nucleation and particle growth on the films. Energy-dispersive X-ray (EDX) analysis data revealed the adsorption of oxygen atoms in the BaTiO₃ film. The direct energy band gap was found to vary (3.84–3.58 eV) as functions of annealing atmosphere and temperature. Photoluminescence (PL) revealed intense emission peaks at 393 and 675 nm. Quenching of PL intensity was observed in films annealed at high temperature and in O₂ atmosphere. This is due to reduction in the oxygen vacancy by the adsorption of oxygen in the film. Luminescence spectra also have been related to the results obtained by SEM and EDX analysis. The change in luminescence intensity of BaTiO₃ thin films makes it suitable for optoelectronic temperature sensor applications.     

On the compactness of tubular heat exchangers

The effect of the open flow area of the intertubular channel on heat transfer parameters in the case of longitudinal flow past tubes is considered using tube-in-tube heat exchangers with smooth and profiled tubes as examples. It is demonstrated that the heat transfer efficiency can be enhanced by reducing the open flow area. By optimizing the tubular and intertubular spaces, it is possible to make the tubular heat exchanger much more compact.     

Factors determining the adoption and impact of a postharvest storage technology

This paper evaluates the determinants and impact of adopting the metal silo—a postharvest storage technology for staple grains—which was disseminated by the Swiss Agency for Development and Cooperation (SDC) from 1983 to 2003 in four Central American countries. The aim of the SDC program was to diminish smallholder farmers’ postharvest losses by facilitating the manufacture and dissemination of metal silos and thereby to improve regional food security. Our empirical analysis is based on a unique data set obtained from a survey of 1,600 households from El Salvador, Guatemala, Honduras and Nicaragua. We employed a double-hurdle model to identify factors that contributed to the adoption of metal silos and used Tobit and standard regression models to assess the impact of adopting the silos on food security and well-being of households. Our results show that both the household demand for metal silos and the impact of their adoption varied across the four countries, demonstrating the relevance of regional policies for their adoption, as well as their impact. Furthermore, our results indicate that, in addition to achieving household self-sufficiency in maize, the main determinants of adoption were household socio-economic characteristics such as age, land ownership, completion of a training course and quality of basic infrastructure. Finally, when considering a group of economic and social indicators of household well-being, we found that, compared to the silo non-adopters, the adopter households experienced a significant improvement in their food security and well-being between 2005 and 2009.     

人丝/锦纶花色纱一浴法染色工艺的探讨

在对人造丝和锦纶两种纤维形态结构及染色性能分析的基础上，从染料、助剂及染浴条件等方面阐述了一浴两步法染色工艺的可行性，并给出具体染色工艺。