Crosslinked TS-1 as stable catalyst for the Beckmann rearrangement of cyclohexanone oxime

Crosslinked TS-1 zeolite materials have been studied in the gas phase Beckmann rearrangement reaction of cyclohexanone oxime to ε-caprolactam. Crosslinking of the zeolite particles resulted in the formation of an additional mesoporosity leading to increased activity in the Beckmann rearrangement reaction. The increased activity can be correlated with the newly created mesopore surface. Possibly more important, together with increased catalytic activity of the materials, the deactivation behavior of the catalysts is very significantly improved.     

A Programmable Display Layer for Virtual Reality System Architectures

Display systems typically operate at a minimum rate of 60 Hz. However, existing VR-architectures generally produce application updates at a lower rate. Consequently, the display is not updated by the application every display frame. This causes a number of undesirable perceptual artifacts. We describe an architecture that provides a programmable display layer (PDL) in order to generate updated display frames. This replaces the default display behavior of repeating application frames until an update is available. We will show three benefits of the architecture typical to VR. First, smooth motion is provided by generating intermediate display frames by per-pixel depth-image warping using 3D motion fields. Smooth motion eliminates various perceptual artifacts due to judder. Second, we implement fine-grained latency reduction at the display frame level using a synchronized prediction of simulation objects and the viewpoint. This improves the average quality and consistency of latency reduction. Third, a crosstalk reduction algorithm for consecutive display frames is implemented, which improves the quality of stereoscopic images. To evaluate the architecture, we compare image quality and latency to that of a classic level-of-detail approach.     

Detailed study on the use of electrospray mass spectrometry to investigate speciation in concentrated silicate solutions

Silicate speciation in aqueous solutions containing tetraalkylammonium hydroxide as template is examined by electrospray mass spectrometry. A thorough study has been carried out to define and optimize the conditions of analysis for a highly concentrated reaction solution of inorganic species--in this case, silicate oligomers--by using different ion source designs. The results reveal specific advantages with respect to the detected species. Condensation of monomers leads to oligomeric units that condense further in different reaction steps to larger species. Potential gas-phase reactions that can disturb characterization of the formed silicate species were intensively investigated and characterized. One reaction that plays a key role is the alkoxylation of Si-OH groups that is caused by two different reactions: first, a reaction of methanolate from the solvent and, second, by the involvement of the template salt, tetramethylammonium hydroxide.     

Recent Advances in Nano- and Macroscale Control of Hexagonal, Mesoporous Materials

Nano- and macroscale control of siliceous MCM-41 type, hexagonal, mesoporous materials are discussed with reference to proposed mechanisms of formation and morphological manipulation. The complex interplay of surfactant silicate chemistry in the numerous synthetic strategies of MCM-41 type materials reported to date are examined. Recent advances in the growth of thin film mesoporous silicates from solid-liquid, air-liquid and liquid-liquid interfaces are reviewed. Extension into three-dimensional silicate structures is made possible through detailed control of shear flow conditions and reaction composition.     

Multi-objective optimization in combinatorial chemistry applied to the selective catalytic reduction of NO with C3H6

A high-throughput approach, aided by multi-objective experimental design of experiments based on a genetic algorithm, was used to optimize the combinations and concentrations of a noble metal–free solid catalyst system active in the selective catalytic reduction of NO with C₃H₆. The optimization framework is based on PISA [S. Bleuler, M. Laumanns, L. Thiele, E. Zitzler, Proc. of EMO'03 (2003) 494], and two state-of-the-art evolutionary multi-objective algorithms—SPEA2 [E. Zitzler, M. Laumanns, L. Thiele, in: K.C. Giannakoglou, et al. (Eds.), Evolutionary Methods for Design, Optimisation and Control with Application to Industrial Problems (EUROGEN 2001), International Center for Numerical Methods in Engineering (CIMNE), 2002, p. 95] and IBEA [E. Zitzler, S. Künzli, Conference on Parallel Problem Solving from Nature (PPSN VIII), 2004, p. 832]—were used for optimization. Constraints were satisfied by using so-called “repair algorithms.” The results show that evolutionary algorithms are valuable tools for screening and optimization of huge search spaces and can be easily adapted to direct the search towards multiple objectives. The best noble metal free catalysts found by this method are combinations of Cu, Ni, and Al. Other catalysts active at low temperature include Co and Fe.     

Hydraulic Alumina Binder for Extrusion of Alumina Ceramics

The present work describes the effect of hydraulic alumina (HA) as a new inorganic binder on extrusion of alumina ceramics. The addition of a small amount of HA imparted significant flowability and rigidity to the extruded alumina. Under optimum processing conditions such as amounts of HA and water, and curing period, alumina rods and tubes were successfully extruded using a single screw extruder. Sintered specimens have achieved a relative density of 97% after sintering at 1600°C for 2 h. Dense alumina samples prepared using organic and inorganic binders had similar mechanical properties, that is, Young's modulus >380 GPa and H _v>2000. These results suggest that HA is a new kind of inorganic binder applicable to the extrusion of ceramics.     

An experimental study on performance and emission characteristics of a hydrogen fuelled spark ignition engine

In the present paper, the performance and emission characteristics of a conventional four cylinder spark ignition (SI) engine operated on hydrogen and gasoline are investigated experimentally. The compressed hydrogen at 20  MPa has been introduced to the engine adopted to operate on gaseous hydrogen by external mixing. Two regulators have been used to drop the pressure first to 300 kPa, then to atmospheric pressure. The variations of torque, power, brake thermal efficiency, brake mean effective pressure, exhaust gas temperature, and emissions of _NOx${\mathrm{NO}}_x$, CO, _CO2${\mathrm{CO}}_2$, HC, and _O2${\mathrm{O}}_2$ versus engine speed are compared for a carbureted SI engine operating on gasoline and hydrogen. Energy analysis also has studied for comparison purpose. The test results have been demonstrated that power loss occurs at low speed hydrogen operation whereas high speed characteristics compete well with gasoline operation. Fast burning characteristics of hydrogen have permitted high speed engine operation. Less heat loss has occurred for hydrogen than gasoline. _NOx${\mathrm{NO}}_x$ emission of hydrogen fuelled engine is about 10 times lower than gasoline fuelled engine. Finally, both first and second law efficiencies have improved with hydrogen fuelled engine compared to gasoline engine. It has been proved that hydrogen is a very good candidate as an engine fuel. The obtained data are also very useful for operational changes needed to optimize the hydrogen fueled SI engine design.     

Capacity of Activated Carbon Derived from Peach Stones by K2CO3 in the Removal of Acid, Reactive, and Direct Dyes from Aqueous Solution

The present research deals with the production of activated carbon by chemical activation using peach stones and its adsorption behavior. The prepared activated carbon was used for the adsorption of three kinds of textile dyes, acid, reactive, and direct dyes, from aqueous solution. The results indicated that the overall adsorption process followed the pseudo-second-order kinetic model. The equilibrium data were found to be well represented by the Langmuir adsorption isotherm model. The calculated adsorption capacities for Reactive Orange 16, Acid Yellow 11, and Direct Red 23 onto activated carbon were 667, 539, and 427?mg?g?1 at 50°C, respectively. Thermodynamic parameters, such as ΔG°, ΔH°, and ΔS°, were also calculated and indicated that the adsorption of dyes onto activated carbon was spontaneous and endothermic in nature.