Catalytic conversion of chloromethane to methanol and dimethyl ether over mesoporous γ-alumina

Mesoporous γ-alumina, mp-γ-Al₂O₃, possessing surface area around 385 m²/g and total pore volume of 2.0 cm³/g was prepared via template-free sol-gel synthesis. The catalytic activity of the prepared alumina for the conversion of chloromethane to dimethyl ether, DME, in the presence of water or methanol was studied in the temperature range of 170-450 °C employing FTIR spectroscopy. In the absence of water and methanol, the fresh surface of mp-γ-Al₂O₃ showed 100% conversion of chloromethane to DME at temperatures between 250 and 350 °C. However, rapid deactivation of the catalyst resulted in a sharp decrease in the conversion to < 5% within a few minutes of reaction. The catalytic activity was noticeably enhanced by adding water vapor to the gas feed resulting in higher conversions to DME and methanol. The catalytic activity and DME selectivity were further enhanced in the presence of methanol instead of water. In the temperature range of 200-300 °C, complete conversions were obtained at the beginning of reactions before they declined to values between 31 and 45% depending on the reaction temperature. It was proposed that the surface hydroxyl groups are the active sites where chloromethane molecules dissociatively adsorb forming adsorbed methoxy ion intermediates. The adsorption of molecular methanol regenerates the surface hydroxyl groups and enhances the formation of adsorbed methoxy ions on the surface which react further with chloromethane or methanol molecules to produce more DME.     

Exploiting the synergy between fractal dimension and lacunarity for improved texture recognition

Fractal dimension measures the geometrical complexity of images. Lacunarity being a measure of spatial heterogeneity can be used to differentiate between images that have similar fractal dimensions but different appearances. This paper presents a method to combine fractal dimension (FD) and lacunarity for better texture recognition. For the estimation of the fractal dimension an improved algorithm is presented. This algorithm uses new box-counting measure based on the statistical distribution of the gray levels of the “boxes”. Also for the lacunarity estimation, new and faster gliding-box method is proposed, which utilizes summed area tables and Levenberg-Marquardt method. Methods are tested using Brodatz texture database (complete set), a subset of the Oulu rotation invariant texture database (Brodatz subset), and UIUC texture database (partial). Results from the tests showed that combining fractal dimension and lacunarity can improve recognition of textures.     

Polymer Carpets

The fabrication of defined polymer objects of reduced dimensions such as polymer‐coated nanoparticles (zero‐dimensional (0D)), cylindrical brushes (1D), and polymer membranes (2D), is currently the subject of intense research. In particular, ultrathin polymer membranes with high aspect ratios are being discussed as novel materials for miniaturized sensors because they would provide extraordinary sensitivity and dynamic range when sufficient mechanical stability can be combined with flexibility and chemical functionality. Unlike current approaches that rely on crosslinking of polymer layers for stabilization, this report presents the preparation of a new class of polymer material, so‐called “polymer carpets,” a freestanding polymer brush grown by surface‐initiated polymerization on a crosslinked 1‐nm‐thick monolayer. The solid‐supported, as well as freestanding, polymer carpets are found to be mechanically robust and to react instantaneously and reversibly to external stimuli by buckling. The carpet mechanics and the dramatic changes of the film properties (optical, wetting) upon chemical stimuli are investigated in detail as they allow the development of completely new integrated micro‐/nanotechnology devices.     

Expert simulation systems—recent developments and applications in flexible manufacturing systems

Flexible Manufacturing Systems (FMS), as a class of automated production systems, are being implemented to increase the flexibility and productivity of discrete part manufacturing. Today, as a result of on-going advances and developments in hardware, this technology is not only becoming more complex to control, but also presenting a number of decision problems to be solved, which, in turn, increases the pressure on both the researchers and practitioners to develop better software algorithms in order to use these extensive hardware systems efficiently.

In the recent literature on FMS, planning problems are classified into strategic, tactical, and operational areas. Each area has been also studied extensively and several solution approaches have been proposed ranging from analytical techniques to simulation and expert systems.

The objective of this paper is to review the recent developments in simulation and to discuss the role of Expert Simulation Systems (ESS) in FMS by identifying possible future research areas.     

Review of Cross-Cultural Studies of Behavior.

Reviews the book, Cross-Cultural Studies of Behavior by Ihsan Al-Issa and Wayne Dennis (see record 1972-06603-000). Cross-cultural behavioural studies have been long neglected in psychology. Further, the published results are widely scattered. The collection of readings by Al-Issa and Dennis are, therefore, a useful adjunct to the class-room literature. The organization of the readings includes sections on Cross-Cultural Studies of Perception, Intellectual Functioning, Personality, Child Rearing and Behavior, Mental Health and Psycholinguistics. There are 39 articles in all representing a good selection of authors prominent in their field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Source coherence impairments in a direct detection direct sequence optical code-division multiple-access system

We demonstrate that direct sequence optical code- division multiple-access (DS-OCDMA) encoders and decoders using sampled fiber Bragg gratings (S-FBGs) behave as multipath interferometers. In that case, chip pulses of the prime sequence codes generated by spreading in time-coherent data pulses can result from multiple reflections in the interferometers that can superimpose within a chip time duration. We show that the autocorrelation function has to be considered as the sum of complex amplitudes of the combined chip as the laser source coherence time is much greater than the integration time of the photodetector. To reduce the sensitivity of the DS-OCDMA system to the coherence time of the laser source, we analyze the use of sparse and nonperiodic quadratic congruence and extended quadratic congruence codes.     

C18 Unsaturated Fatty Acid Selectivity of Lipases During the Acidolysis Reaction Between Tripalmitin and Oleic,Linoleic, and Linolenic Acids

The C18 unsaturated fatty acid (UFA) selectivity of three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanuginosa, Lipozyme RM IM from Rhizomucor miehei, and Novozym 435 from Candida antarctica, was determined in acidolysis conducted in hexane. Tripalmitin with a mixture of equimolar quantities of C18 UFAs was used as the substrate. Significantly different incorporation rates were observed for C18 UFAs used (p < 0.05). The highest incorporation was obtained for all three C18 UFAs with Novozym 435 followed by Lipozyme RM IM and Lipozyme TL IM catalyzed acidolysis under default conditions (substrate mole ratio 1:1; temperature 50 °C; reaction time 6 h; enzyme dosage 10%). Incorporation of the equimolar quantities of C18 UFAs was in the order C18:3 > C18:2 > C18:1 which also reflects C18 UFAs preferences of the lipases. The effects of operating variables on incorporation or UFA selectivity of lipases were also investigated. Among the experimental parameters including the mole ratio of fatty acid to triolein, temperature, enzyme dosage, and time on incorporation, the effect of the substrate mole ratio on UFA selectivity was greater than those of the others.     

Microscopic investigation of pollen morphology of Brassicaceae from Central Punjab‐Pakistan

The intention of the current study is to provide an account on the palynological features of Brassicaceae from Central Punjab‐Pakistan as a basis for future studies. Different morpho‐palynological characteristics both qualitative and quantitative were analyzed during this research which includes shape of pollen, diameter of pollen, P/E ratio, exine sculpturing, thickness of exine, type of pollen, shape and size of lumens, and thickness of murus. Taxonomic keys were also constructed based on pollen morphological characters for correct identification of species. This study aims to provide detailed information of pollen diversity and their exine structure based on both qualitative and quantitative characters by using Light microscopy and Scanning electron microscopy. Shape of pollen is mostly prolate, but some species also have sub‐prolate to spheroidal prolate types. Exine ornamentation in most species was reticulate, whereas micro reticulate (one species) and coarsely reticulate (one species) exine also observed in some pollen. All the pollen mentioned in this study have tricolpate apertures. Variation found in thickness of exine and other characters proved to be helpful at generic and specific level. The results reinforced the significance of pollen morphological features of family Brassicaceae and aid for valuable taxonomic tool in plant systematics.     

In situ growth of gold nanoparticles on latent fingerprints-from forensic applications to inkjet printed nanoparticle patterns

Latent fingerprints are made visible in a single step by in situ growth of gold nanoparticles on ridge patterns. The chemicals, among the essential components of human sweat, found responsible for the formation and assembly of gold nanoparticles are screened and used as ink to write invisible patterns, using common ball pen and inkjet printer, which are then developed by selectively growing gold nanoparticles by soaking them in gold salt solution.