CATALYTIC COMBUSTION OF METHANE OVER PALLADIUM-BASED CATALYSTS

Palladium-based catalysts are widely applied in exhaust catalytic converter and catalytic combustion systems. The mechanism for methane oxidation on a Pd-based catalyst is complex. Catalyst activity is influenced by variations in the process pressure and temperature, by the gas mixture composition, by the type of support and various additives, and by pretreatment under reducing or oxidizing atmospheres. In this paper, we review the literature on supported Pd catalysts for combustion of methane. The mechanisms involved are discussed taking into consideration the oxidation/reduction mechanisms for supported palladium, poisoning, restructuring, the form of oxygen on the surface, methane activation over Pd and PdO phases, and transient behavior. Our review helps explain the array of experimental results reported in the literature.     

Full phenol peroxide oxidation over Fe-MMM-2 catalysts with enhanced hydrothermal stability

Iron-containing mesoporous mesophase materials Fe-MMM-2 have been synthesized by a sol–mesophase route under mild acidic conditions and characterized by DRS-UV–vis, XRD, and N₂ adsorption measurements. It was found that pH of the synthesis solution and iron content in the samples affect both the textural characteristics and the state of iron atoms. Isolated iron species predominate in silica framework under Fe < 2 wt% and pH  1.0 or Fe  1 wt% and pH < 2.0. These species are stable to leaching and highly active in full H₂O₂-based phenol oxidation. The increase in iron loading and pH of the synthesis solution lead to the agglomeration and formation of oligomeric iron species, which, in turn, results in the reduction of the catalytic activity of Fe-MMM-2 and the increase of iron leaching.     

Graphene-like film CVD on e-beam exposed SiO2/Si by the pyrolysis of different oxygen-containing precursors

ABSRTACT

We have previously found that pyrolysis of ethanol vapor on charge pre-patterned SiO₂/Si substrate leads to controllable deposition of graphene-like films (GLFs). In this work we aim at the GLFs synthesis from acetone and isopropanol on SiO2/Si exposed to an electron beam with various energies and doses. Electron beam induced charge in 200?nm SiO₂ is determined by the shift of the capacitance-voltage characteristics. Synthesized GLFs are characterized using Raman spectroscopy and atomic force microscopy. It is shown that the thickness of GLF on SiO₂/Si increase together with the preliminary exposure dose and inversely associated with electron energies.     

Manufacturing pharmaceutical granules: Is the granulation end-point a myth?

The moist agglomeration process by high-shear mixing/granulation, i.e. the wet massing, screening and subsequent drying is a wide spread but critical unit operation. Since for decades formulators are looking for the correct “end-point” of this important process, i.e. when do you need to stop massing or stop with the addition of granulating liquid? What is the correct amount of granulating liquid? A similar situation exists in case of the moist agglomeration in fluidized bed equipment. In the latter case the simultaneous drying of the still moist granules have to be taken into account. Recently a science-based virtual equipment simulator could be developed mimicking the granule size evolution in a fluidized bed granulator during the addition of granulating liquid. For the simultaneous drying the Mollier chart is used. With this virtual equipment simulator it is possible to simulate “crash situations”, i.e. by overwetting or by an incorrect use of the parameter setting. However the determination of the “end-point” depends only on the operator, who desires a certain granule size distribution and a well-defined final moisture content of the batch. Thus the existence of a process intrinsic “end-point” has to be questioned. The same situation can be reported in case of high-shear mixing/granulation based on many years of research. In fact nobody could clearly show the existence of an intrinsic “end-point”. However during the continuous addition of a granulating low viscous liquid a sudden increase in power consumption can be measured, which levels off. Such a measurement depends on the formulation and leads to an “early signal” not to the “end-point”. This signal can be used for a tight control of the granulation process and leads to a low batch to batch variability in the final granule size distribution. The latter is the goal of the PAT (Process Analytical Technology) Initiative emphasizing “Quality by Design”.     

高速运放支持红外接近检测设计

IR接近检测传感器广泛用于检测物体是否存在,与参照物之间的距离,或同时检测两者.具体应用包括:测速、自控式水龙头,自动计数器或传送带物体检测,打印机纸张边缘检测等其它应用.     

The pulsed eddy current response to applied loading of various aluminium alloys

In this paper the pulsed eddy current (PEC) response of a range of heat treatable and non-heat treatable aluminium alloys (AA-1050, 2024, 5083 and 7075) to applied stress well below the elastic limit is studied. The effect of prior heat treatment and prior plastic deformation on the stress dependency of the pulsed eddy current response is quantified using the peak value of the PEC difference signal. In certain cases non-linear stress responses are measured. Because it is well known that the effect of stress on conductivity is anisotropic both isotropic (circular) probes and directional (rectangular) probes are compared. It is found that both prior plastic work and heat treatment condition can have a strong effect on the stress coefficients, even changing the sign of the stress dependence. The implications of these effects for the future characterisation of residual stress state by PEC are discussed.     

A Fully Integrated 0.13 μm CMOS Low-IF DBS Satellite Tuner Using Automatic Signal-Path Gain and Bandwidth Calibration

This paper presents the first low-IF fully integrated receiver for DBS satellite TV applications realized in 0.13 mum CMOS. A wideband ring oscillator based frequency synthesizer having a large frequency step was used to downconvert a cluster of channels to a coarsely defined low-IF frequency, while the second downconversion to baseband was performed in the digital domain. Eliminating the oscillator inductors reduced the parasitic magnetic coupling from the digital core, allowing a single-chip integration of the sensitive tuner and the noisy digital demodulator. A significant die area reduction was achieved by using a single oscillator to cover the entire satellite TV spectrum, while a noise attenuator was cascaded with the PLL loop filter to reduce the equivalent tuning gain. The low-IF architecture allowed a discrete-step AGC that improves both tuner noise and linearity performance. Tuner gain and IF corner frequency were calibrated using replica ring oscillators that are tuned up to the onset of oscillations. The tuner specifications include: 90 dB gain range, 9 dB noise figure at max gain, +25 dBm IIP3 at min gain, 1.3degrms integrated phase noise, les50 dBc spurs, 0.7 W power consumption from dual 1.8/3.3-V supplies, and 1.8times1.2 mm ² die area     

Controlled radical polymerization of N,N-dimethylaminoethyl methacrylate using triazolinyl as counter radical

Summary The role of the triazolinyl radical as additive for controlled radical polymerisation is investigated for N,N-dimethylaminoethyl methacrylate (DMAEMA) as polar monomer. A linear increase of the molecular weight with conversion and first-order kinetics are observed proving the controlled behaviour of the polymerization. The end-functionalisation of the obtained polymers was proven by both GPC und UV-spectroscopy. Furthermore, various amphiphilic block copolymers were obtained by chain extension with styrene, methyl methacrylate and ethyl methacrylate. In all cases monomodal GPC curves were obtained indicating an almost quantitative reinitiation.     

Imperfect repair and lifesaving in heterogeneous populations

In this theoretical paper we generalize the notion of minimal repair to the heterogeneous case, when the lifetime distribution function can be modeled by continuous or a discrete mixture of distributions. The statistical (black box) minimal repair and the minimal repair based on information just before the failure of an object are considered. The corresponding failure (intensity) rate processes are defined and analyzed. Demographic lifesaving model is also considered: each life is saved (cured) with some probability (or equivalently a proportion of individuals who would have died are now resuscitated and given another chance). Those who are saved experience the statistical minimal repair. Both of these models are based on the Poisson or non-homogeneous Poisson processes of underlying events, which allow for considering heterogeneity. We also consider the new model of imperfect repair in the homogeneous case and present generalizations to the heterogeneous setting.     

Spurious consensus and opinion revision: Why might people be more confident in their less accurate judgments?

In the interest of improving their decision making, individuals revise their opinions on the basis of samples of opinions obtained from others. However, such a revision process may lead decision makers to experience greater confidence in their less accurate judgments. The authors theorize that people tend to underestimate the informative value of independently drawn opinions, if these appear to conflict with one another, yet place some confidence even in the spurious consensus, which may arise when opinions are sampled interdependently. The experimental task involved people's revision of their opinions (caloric estimates of foods) on the basis of advice. The method of sampling the advisory opinions (independent or interdependent) was the main factor. The results reveal a dissociation between confidence and accuracy. A theoretical underlying mechanism is suggested whereby people attend to consensus (consistency) cues at the expense of information on interdependence. Implications for belief updating and for individual and group decisions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)