Oxide-ion conductivity of calcia- and yttria-stabilized zirconias prepared by a rapid-combustion route

Calcia- and yttria-stabilized zirconias have been synthesised by a novel rapid-combustion route. The oxide-ion conductivities of these stabilized zirconias are comparable to these of commercially prepared samples. Variations in grain boundary impedance of calcia- and yttria-stabilized zirconias with composition and temperature are presented.     

Remote mobile manipulation with the centauro robot: Full‐body telepresence and autonomous operator assistance

Solving mobile manipulation tasks in inaccessible and dangerous environments is an important application of robots to support humans. Example domains are construction and maintenance of manned and unmanned stations on the moon and other planets. Suitable platforms require flexible and robust hardware, a locomotion approach that allows for navigating a wide variety of terrains, dexterous manipulation capabilities, and respective user interfaces. We present the CENTAURO system which has been designed for these requirements and consists of the Centauro robot and a set of advanced operator interfaces with complementary strength enabling the system to solve a wide range of realistic mobile manipulation tasks. The robot possesses a centaur‐like body plan and is driven by torque‐controlled compliant actuators. Four articulated legs ending in steerable wheels allow for omnidirectional driving as well as for making steps. An anthropomorphic upper body with two arms ending in five‐finger hands enables human‐like manipulation. The robot perceives its environment through a suite of multimodal sensors. The resulting platform complexity goes beyond the complexity of most known systems which puts the focus on a suitable operator interface. An operator can control the robot through a telepresence suit, which allows for flexibly solving a large variety of mobile manipulation tasks. Locomotion and manipulation functionalities on different levels of autonomy support the operation. The proposed user interfaces enable solving a wide variety of tasks without previous task‐specific training. The integrated system is evaluated in numerous teleoperated experiments that are described along with lessons learned.     

Study on Tribological Behaviour of Al/SiC/MoS2 Hybrid Metal Matrix Composites in High Temperature Environmental Condition

Silicon - The current study investigates the tribological behaviour of aluminium hybrid composite reinforced with SiC and MoS2 at various temperature environments. The hybrid metal matrix...     

The effect of vibratory drilling on hole quality in polymeric composites

The anisotropy of fiber-reinforced plastics (FRP) affects the chip formation and thrust force during drilling. Delamination is recognized as one of the major causes of damage during drilling of fiber reinforced plastics, which not only reduces the structural integrity, but also has the potential for long-term performance deterioration. It is difficult to produce good quality holes with high efficiency by conventional drilling method. This research concerning drilling of polymeric composites aims to establish a technology that would ensure minimum defects and longer tool life. Specifically, the authors conceived a new drilling method that imparts a low-frequency, high amplitude vibration to the workpiece in the feed direction during drilling. Using high-speed steel (HSS) drill, a series of vibratory drilling and conventional drilling experiments were conducted on glass fiber-reinforced plastics composites to assess thrust force, flank wear and delamination factor. In addition, the process-status during vibratory drilling was also assessed by monitoring acoustic emission from the workpiece. From the drilling experiments, it was found that vibratory drilling method is a promising machining technique that uses the regeneration effect to produce axial chatter, facilitating chip breaking and reduction in thrust force.     

Chromatographic separation of alkylated depolymerized Neyveli lignite

The study of macromolecular structure of coal has been subjected to intense research. Neyveli lignite was depolymerized using phenol and phosphotungstic acid and the resultant product was subsequently alkylated. The t-butylated depolymerized lignite exhibited enhanced extractability in organic solvents. The t-butylated depolymerized lignite was fractionated into different components using column chromatography (CC). Three major compounds were isolated and were characterized by FTIR, ¹H NMR and Mass spectral techniques.     

Superhydrophobic polytetrafluoroethylene thin films with hierarchical roughness deposited using a single step vapor phase technique

Superhydrophobic polytetrafluoroethylene films with hierarchical surface roughness were deposited using pulse electron deposition technique. We were able to modulate roughness of the deposited films by controlling the beam energy and hence the electron penetration depth. The films deposited at higher beam energy showed contact angle as high as 166°. The scanning electron and atomic force microscope studies revealed clustered growth and two level sub-micron asperities on films deposited at higher energies. Such dual-scale hierarchical roughness and heterogeneities at the water-surface interface was attributed to the observed contact angle and thus its superhydrophobic nature.     

Formation Kinetics of Monomeric Cyclic Fatty Acid Methyl Esters of Alpha-Linolenic Acid: Effects of Mono cis/trans Isomers

Cyclic fatty acid monomers (CFAM) are formed at low levels in edible oils during thermal processing operations such as frying or refining, and inevitably become part of the diet. These proatherogenic agents may increase the levels of oxidative stress markers, and induce hepatomegaly and steatosis. However, the kinetics involved in their formation is not well known. The objective of the present study was to evaluate the effects of cis and trans isomers on cyclization reactions involved in the thermal transformation of alpha-linolenic acid (ALA). Geometrical isomers of ALA were obtained from all-cis ALA by nitric acid treatment. Mono-trans isomers were concentrated using silver nitrate-silica gel chromatography. All-cis ALA, isomerized ALA, and a fraction at 85% mono-trans isomers were heat treated at 275 °C in hexadecane for periods up to 24 hours, and the formation of geometrical isomers and CFAM was monitored by GC. The results show that mono-trans isomers at carbon 9 and carbon 15 form CFAM at an accelerated rate, compared to the corresponding cis isomers, resulting in the formation of higher levels of CFAM over shorter time periods. The validation of the kinetic model was performed by solving simultaneously and nonlinearly fitting the system of coupled differential equations with experimental data. Good agreement was found between the experimental data and the predicted values. This work suggests that the use of polyunsaturated vegetable oils over extended periods for thermal processing of food may result in the formation of CFAM, in particular, if mono-trans isomers are present in the oil.     

Conjugated linoleic acid formation by hydrogenation/isomerisation of safflower oil over bifunctional structured catalyst Rh/SBA‐15

Directed isomerisation of safflower oil under very low hydrogen partial pressure of 7 psi over a novel bifunctional highly structured rhodium‐based catalyst (Rh/SBA‐15), having narrow pore size distribution ranging from 4 to 8 nm, and BET‐specific surface of ≈1,000 m² g^?1, was investigated as a new chemocatalytic approach for vegetable oil hardening and simultaneously producing health‐beneficial conjugated linoleic acids (CLA). Time course profiles of (cis‐9, trans‐11)‐; (cis‐10, trans‐12)‐; (trans‐10, cis‐12)‐; (cis,cis)‐ and (trans, trans)‐octadecadienoic isomers (CLAs) as well as the other fatty acids traditionally encountered during the hydrogenation of vegetable oils are presented and discussed under selected process conditions. Preliminary results show that it is possible to tailor characteristics of the hydrogenation catalyst in such way to confer its bi‐functional activity: hydrogenation and conjugation isomerisation. © 2011 Canadian Society for Chemical Engineering