Carbonyl‐precursor‐based W/Al2O3 and CoW/Al2O3 catalysts: characterization by temperature‐programmed methods

Carbonyl‐precursor‐based W/Al₂O₃ and bimetallic CoW/Al₂O₃ catalysts were prepared by gas‐phase adsorption in a fluidized‐bed reactor. The surface species formed during the gradual and controlled preparation process were studied by temperature‐programmed methods. Interactions on the surface were investigated as a function of metal loading by temperature‐programmed oxidation (TPO) and oxygen pulse chemisorption (PCO). A clear relationship was observed between decarbonylation treatment and the tungsten species formed. Total acidity of the samples was determined by temperature‐programmed desorption of ammonia (NH₃‐TPD). The NH₃‐TPD measurements, together with previous activity studies, suggest a relationship between total acidity and hydrotreating activity. The results of PCO and NH₃‐TPD measurements indicate that when the controlled gas‐phase preparation method is applied to zerovalent carbonyl precursor, the unfavourable formation of tungsten oxide can be minimized. This revised version was published online in July 2006 with corrections to the Cover Date.     

Multifunction spectrometer for optical inspection of red wine

The main goal of this study was to develop an apparatus that makes it possible to measure both, color, refractive index and light scattering (turbidity) of red wines using a single device only. Typically such measurement of red wine quality requires three different measurement devices. As an example of the efficiency of the present device we studied the change of the thermo-optical and time-dependent optical properties of red wine samples. Here we report on change of optical properties of two Merlot wine samples, which were obtained by opening authentic red wine bottles and preserving a set of samples both at room and refrigerator temperature for 26 days, respectively. The interesting feature with both red wine samples was that the light scattering, i.e. the turbidity of the samples, increased as a function of time due to oxidation process. It is suggested that the multifunction spectrophotometer can be applied for optical inspection of red and other wine products.     

Quantitative Insight into the Design of Compounds Recognized by the L‐Type Amino Acid Transporter 1 (LAT1)

L ‐Type amino acid transporter 1 (LAT1) is a transmembrane protein expressed abundantly at the blood–brain barrier (BBB), where it ensures the transport of hydrophobic acids from the blood to the brain. Due to its unique substrate specificity and high expression at the BBB, LAT1 is an intriguing target for carrier‐mediated transport of drugs into the brain. In this study, a comparative molecular field analysis (CoMFA) model with considerable statistical quality (Q²=0.53, R²=0.75, Q² SE=0.77, R² SE=0.57) and good external predictivity (CCC=0.91) was generated. The model was used to guide the synthesis of eight new prodrugs whose affinity for LAT1 was tested by using an in situ rat brain perfusion technique. This resulted in the creation of a novel LAT1 prodrug with L ‐tryptophan as the promoiety; it also provided a better understanding of the molecular features of LAT1‐targeted high‐affinity prodrugs, as well as their promoiety and parent drug. The results obtained will be beneficial in the rational design of novel LAT1‐binding prodrugs and other compounds that bind to LAT1.     

On time-symmetry in cellular automata

The notion of reversibility has been intensively studied in the field of cellular automata (CA), for several reasons. However, a related notion found in physical theories has been so far neglected, not only in CA, but generally in discrete dynamical systems. This is the notion of time-symmetry, which refers to the inability of distinguishing between backward and forward time directions. Here we formalize it in the context of CA, and study some of its basic properties. We also show how some well-known CA fit into the class of time-symmetric CA, and provide a number of results on the relation between this and other classes of CA. The existence of an intrinsically universal time-symmetric CA within the class of reversible CA is proved. Finally, we show the undecidability of time-symmetry for CA of dimension 2 or higher, even within the class of reversible CA. The case of dimension 1 is one of several open questions discussed in the conclusions.     

Using 2- and 2 -dimensional seed filling in view lattice to accelerate volumetric rendering

In this paper we propose new methods for calculating the projection of an opaque 3-dimensional 6-connected volumetric object into a two-dimensional view using 2- and 2 -dimensional seed-filling in the view space. When a 3-dimensional volumetric data set is sampled by parallel rays at a resolution exceeding the Nyquist ratio, the 6-connectivity of objects is maintained from volume lattice to view lattice. Given a seed point for each 6-connected object in the volumetric data set, a seed-filling algorithm may access all sample points in view lattice, while simultaneously composing the rendered view. The algorithms presented in this paper minimize the number of voxels that need to be processed. We implemented these methods on a general purpose computer architecture and tested them with several artificial and real-life medical volumetric data sets. It is shown that the algorithms may be used to speed up the parallel ray casting of opaque medical objects. The actual frame rate achieved by the combined method allows interactive (10 frames/sec) rotation of the object on a common single-processor personal computer without specialized hardware.     

Compressibility of porous TiO2 nanoparticle coating on paperboard

Compressibility of liquid flame spray-deposited porous TiO₂ nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO₂ nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure.

PACS

61.46.-w; 68.08.Bc; 81.07.-b     

An automated methodology to select functional co-simulation configurations

Multibody System Dynamics - The development of machinery often requires system-level analysis, in which non-mechanical subsystems, such as hydraulics, need to be considered. Co-simulation allows...     

Strength retention of self-reinforced,absorbable polyglycolide rods in hydrolytic environment

Absorbable polyglycolide suture fibers were sintered with the compression molding techniques to cylindrical rods at temperatures between 205°C and 232°C for 3–5 min with final pressures of 50–80 N/mm². The cylindrical rods had nominal diameters between 1.5–4.5 mm and a length of 50 mm. The initial bending moduli and the initial bending strengths of the rods were between 9–15 GPa and 220–430 MPa, respectively. The shear strengths of the rods were between 165–255 MPa. The hydrolytic loss of mechanical strength of the above self-reinforced, absorabable polyglycolide rods were studied in phosphate buffer at 37°C and 77°C. It was found that the rate of strength loss decreases with the increasing diameter of the rods. On the other hand, the rate of strength loss increases when the temperature of the buffer solution is raised. The strength, retention time at 37°C was between 7–10 weeks showing that the loss of mechanical strength of self-reinforced polyglycolide rods occurs more rapidly in vivo than in vitro.     

Detection of irregularities in regular patterns

Regular patterns, as defined in this study, are found in areas of industry and science, for example, halftone raster patterns used in the printing industry and crystal lattice structures in solid state physics. The need for quality inspection of products containing regular patterns has aroused interest in the application of machine vision for automatic inspection. Quality inspection typically corresponds to detecting abnormalities, defined as irregularities in this case. In this study, the problem of irregularity detection is described in analytical form and three different detection methods are proposed. All the methods are based on characteristics of the Fourier transform to compactly represent regular information. The Fourier transform enables the separation of regular and irregular parts of an input image. The three methods presented are shown to differ in their generality and computational complexities.