Purification of 2-mercaptobenzothiazole by solvent extraction

−Purification of 2-mercaptobenzothiazole (91.9% purity) by solvent extraction was studied. The extraction of impurities present in crude 2-MBT (e.g. benzothiazole, sulfides and sulfur containing compounds) was carried out at temperatures between 70-180°C using various solvents and their mixtures of different polarity. The highest purity of 2-MBT, above 99% was obtained using nitrobenzene, toluene and ethanol, even at a concentration of 2-MBT above 50 wt%. Increasing temperature and decreasing concentration of the raw material have a positive influence on the purification process. A comparable efficiency of purification was observed also with mixed solvents, (toluene with ethanol, acetone and aniline) possessing the same polarities. A correlation between the polarity indexes (PI) of mixed solvents and experimentally obtained purity of 2-MBT was found. The highest purity of 2-MBT provides extraction of the raw material with mixed solvents having PI 3.8-4.4.     

Investigation of electrically conductive acrylonitrile‐butadiene rubber

Electrically conductive acrylonitrile‐butadiene rubbers (NBRs) containing carbon black (CB) as conductive filler were prepared in order to investigate their electrical and mechanical properties. The effects of conductive CB loading, temperature, acrylonitrile content, crosslinking density of vulcanizates, and plasticizer on conductivity were studied. The change in electrical conductivity of NBRs with different amounts of CB showed that there is a certain critical point (percolation threshold) where a significant decrease in electrical resistivity (increase in conductivity) is observed. Mechanical properties such as tensile strength, elongation to break, and surface hardness of vulcanized NBRs were measured. It was found that the percolation threshold was 5 phr of CB for the NBR/CB composites. J. VINYL ADDIT. TECHNOL., 13:71–75, 2007. © 2007 Society of Plastics Engineers.     

Spinning viscose technical yarn into a bicomponent precipitation bath

Conclusions -- The possibility has been demonstrated of preparing viscose yarn by the centrifugal method from a viscose containing additions of urea by spinning into a bicomponent precipitation bath containing sulfuric acid and sodium sulfate.-- Optimum conditions for spinning viscose yarn have been established: a sulfuric acid content of 115 g/l in the precipitation bath, a urea content of 2.5% based on weight of -cellulose in the viscose, and an orientation stretch of 22%.-- Specimens of viscose yarn having a linear density of 13.3 tex have been prepared with a relative breaking load of up to 19 cN/tex, an elongation at break of 17–19%, and a mean squared deviation in dyeing nonuniformity of 0.8–1.0.Translated from Khimicheskie Volokna, No. 4, pp. 33–34, July–August, 1990.     

Oxidation behaviour of titanium-containing brazing filler metals

Brazements on alumina or partially stabilized zirconia (PSZ) of four silver- or copper-based brazing filler metals that contain titanium to promote wetting of and adherence to structural ceramics, were exposed in a thermogravimetric analyser at temperatures up to 700°C to atmospheres of 100% O₂, Ar-20% O₂ and Ar-3 p.p.m. O₂. The alloys included Cu-41.1Ag-3.6Sn-7.2Ti, Ag-44.4Cu-8.4Sn-0.9Ti, Ag-41.6Cu-9.7Sn-5.0Ti and Ag-37.4Cu-10.8In-1,4Ti, at%. All formed external oxides that were more or less protective under all of the test conditions studied. The growth of the oxides followed a parabolic time law. The gains in weight due to oxidation observed were small, ranging (for 45 h exposure at 400 °C to Ar-20% O₂) from 0.20 mgcm⁻² for the Ag-37.4Cu-10.8In-1.4Ti alloy to 0.46 mgcm⁻² for Cu-41.1Ag-3.6Sn-7.2Ti. As expected, weight gain increased with increasing temperature or . Unexpectedly, the titanium played a minor role in the scale formed on any of the filler metals with a titanium oxide, TiO₂, being found on only one alloy — Ag-41.6Cu-9.7Sn-5.0Ti. The brazements on PSZ gained weight at a higher rate than comparative brazements on alumina. We attribute this behaviour to oxygen transport through the zirconia resulting in the growth of an interfacial layer of titanium oxide.     

Fabrication of fine-grain piezoelectric ceramics using reactive calcination

Fine-grain piezoelectric ceramics with the formula Pb(Zr_0.53Ti_0.47)O₃(PZT) were prepared by a reactive calcination process. Using conventional materials and processing techniques, highly reactive powders of PZT were achieved by calcining to or near the point of maximum volume expansion, whereby associated morphological changes resulted in highly reactive powder. Upon milling, powders <0.3 m were readily obtained allowing densification at temperatures <1000°C. The B-site precursor method, whereby the ZrO₂ and TiO₂ oxides were pre-reacted prior to reaction with PbO, further enhanced reactivity by eliminating intermediate reactions and subsequent phase(s) which can hinder densification and overall homogeneity. Highly dense piezoceramics with grain sizes 1 to 2 m exhibiting dielectric and piezoelectric characteristics comparable to conventionally prepared large grain size materials were obtained.     

In-store shopping with location-based retail apps: perceived value,consumer response,and the moderating effect of flow

Bricks-and-mortar retailers have recently begun to utilize mobile applications delivering location-based services (LBS) as part of their omni-channel strategy to provide consumers with new in-store experiences. In light of this trend, this study examined how consumers’ value perception influences their intention to use LBS in the store and their behavioral responses as well as the moderating effect of flow on the relationships between the perceived benefits/costs and the perceived value of LBS usage. The results indicated that benefits (perceived usefulness and perceived enjoyment) and costs (perceived complexity and perceived privacy risk) were influential antecedents shaping consumers’ value perception of LBS, which in turn impacted their intention to use LBS and behavioral responses (search and purchasing using LBS). Also, we found that the negative relationship between the perceived costs and perceived value was attenuated in high flow states than in low flow states

     

Application of Fuzzy Moving Sliding Surface Approach for Container Cranes

International Journal of Control, Automation and Systems - In this paper, we consider the fuzzy moving sliding surface anti-sway control problem for container cranes. We first introduce the dynamic...     

Design of a Sliding Mode Controller with Fuzzy Rules for a 4-DoF Service Robot

In this study, a novel control strategy that combines a fuzzy system and the sliding mode controller is proposed for improving stability and achieving high-accuracy control in service robots. Based on the kinematic and dynamic models of a 4-degrees of freedom manipulator, and the observed tracking error using a low-cost inertial sensor, the proposed fuzzy sliding mode controller (FSMC(IMU)) is designed to generate appropriate torques at robot joints. The FSMC(IMU) controller parameters are adjusted through a fuzzy rule that determines the state of the system. The error in trajectory tracking is reduced through this. The gain value K can be finely adjusted by fuzzy control by observing the degree of vibration after entering the sliding mode surface. The larger the observed vibration value, the faster the fuzzy controller follows the given input trajectory by selecting a smaller gain value K and reducing jitter due to the sliding mode control’s discontinuous switch characteristics. When the degree of error is small, it achieves faster and more accurate control performance than when the observer is not used. The stability of the FSMC(IMU) system is verified via disturbance experiments. The experimental data are compared with the conventional sliding mode controller and proportional-derivative control. The experimental results demonstrate that the proposed FSMC(IMU) controller is stable, fast, and highly accurate in controlling service robots.

     

Companion robots for older adults: Rodgers’ evolutionary concept analysis approach

Intelligent Service Robotics - This study aims to analyze the concept of companion robots for older adults from the perspective of nursing. This study employed a concept analysis. The literature...     

Enhancement of the hydrogen storage properties of Mg/C nanocomposites prepared by reactive milling with molybdenum

The effect of Mo on the morphology, crystal structure and hydrogen sorption properties of Mg/C composites prepared by reactive milling was studied. Transmission electron microscopic(TEM) observation shows that Mg/C composites prepared with the addition of Mo are of nanoscale with particle size about 20-120 nm after 3 h of milling under 1 MPaH_2. MgH_2 of tetrahedral crystal structure predominates in the materials with the geometric shape of oblique hexagonal prism. From X-ray diffraction(XRD) and hydrogen content studies, Mo and crystallitic carbon have a synergistic effect on promoting the hydrogenation rate in the reactive milling process. From differential scanning calorimetric(DSC) studies, the dehydrogenation peak temperature of the Mg/C materials with Mo is lowered to 299-340 ℃.