Phase equilibria in the Er–Al–Si system at 873 K

The isothermal cross-section of the phase diagram of the system Er–Al–Si at 873 K was constructed based on X-ray powder diffraction. The existence of the compounds Er₂Al₃Si₂ (Y ₂Al₃Si₂-type structure), ErAlSi (YAlGe), Er₂AlSi₂ (W₂CoB₂), and Er₂Al_1.5Si_1.5 (Mo₂FeB₂) were confirmed and the formation of three new ternary alumosilicides was established: ErAl_2.8Si_0.2 (HT-PuAl₃,hP24,P6₃/mmc,a=0.60295(4),c=1.42308(9) nm),∼Er₅Al₆Si₄ (unknown structure), and Er₆Al₃Si (Tb₆Al₃Si,tI80,I4/mcm,a=1.1436(2),c=1.4854(2) nm).     

Hybrid image‐based collision detection in Java 3D

Collision detection is highly important in computer graphics and virtual reality. Most collision detection methods are object‐based, relying on testing the geometrical interference of objects, and their performance therefore depends on the geometrical complexity of the objects. Recently, image‐based methods have gained increasing acceptance for their simplicity in implementation, robustness with respect to the object geometry, and the potential to distribute the computational burden onto graphics hardware. However, all existing image‐based methods require direct calls to OpenGL, but so far there is no direct way to access OpenGL through the Java 3D API. Although Java 3D provides its own built‐in collision detection classes, they are either incorrect or inefficient. In this paper, we present a hybrid image‐based collision detection method in Java 3D, which incorporates the Java 3D built‐in collision detection and the image‐based collision detection in our specially devised scene graph. In addition, we take advantage of the fact that the 3D position of successive offscreen views (i.e. virtual views perceived by the probing object) does not change significantly and thereby reduce the occurrences of offscreen rendering, so that the collision detection becomes even faster (up to 50% in our case). Experimental results prove the correctness and efficiency of our method. Copyright © 2006 John Wiley & Sons, Ltd.     

Microarrays assembled in microfluidic chips fabricated from poly(methyl methacrylate) for the detection of low-abundant DNA mutations

Low-density arrays were assembled into microfluidic channels hot-embossed in poly(methyl methacrylate) (PMMA) to allow the detection of low-abundant mutations in gene fragments (K-ras) that carry point mutations with high diagnostic value for colorectal cancers. Following spotting, the chip was assembled with a cover plate and the array accessed using microfluidics in order to enhance the kinetics associated with hybridization. The array was configured with zip code sequences (24-mers) that were complementary to sequences present on the target. The hybridization targets were generated using an allele-specific ligase detection reaction (LDR), in which two primers (discriminating primer that carriers the complement base to the mutation being interrogated and a common primer) that flank the point mutation and were ligated joined together) only when the particular mutation was present in the genomic DNA. The discriminating primer contained on its 5'-end the zip code complement (directs the LDR product to the appropriate site of the array), and the common primer carried on its 3' end a fluorescent dye (near-IR dye IRD-800). The coupling chemistry (5'-amine-containing oligonucleotide tethered to PMMA surface) was optimized to maximize the loading level of the zip code oligonucleotide, improve hybridization sensitivity (detection of low-abundant mutant DNAs in high copy numbers of normal sequences), and increase the stability of the linkage chemistry to permit re-interrogation of the array. It was found that microfluidic addressing of the array reduced the hybridization time from 3 h for a conventional array to less than 1 min. In addition, the coupling chemistry allowed reuse of the array > 12 times before noticing significant loss of hybridization signal. The array was used to detect a point mutation in a K-ras oncogene at a level of 1 mutant DNA in 10,000 wild-type sequences.     

Investigation of the transition from tunneling to impact ionization multiplication in silicon p-n junctions

White noise spectra of diodes breaking down between 1·5 and 5 V have been used to investigate the details of the transition from tunneling to avalanche breakdown in silicon p-n junctions. It is found that the transition and carrier multiplication in these junctions is dominated by the influence of the threshold energies for ionization. Because this influence is not explicitly taken into account in the existing theories of carrier multiplication and noise, they are not applicable to low breakdown voltage diodes. Consequently, a multiplication onset model and alternate schemes for calculating the DC multiplication and noise in low breakdown voltage diodes are developed.Analysis of the noise data indicates that the threshold energies for ionization depend slightly on junction widths and, for the diodes employed in this study, range between 1·66–1·9 eV for electrons and 1·79–2·04 eV for holes. The minimum distance between ionizing collisions is found to range from 190 to 240 A for electrons and 200 to 250 A for holes.Application of the threshold energies for ionization to the multiplication onset model permits evaluation of the doping densities on both sides of the step junctions. From it, it is determined that the solubility of aluminum in silicon is N_A = 9·5 ± 0·5 × 10¹⁸ cm^?3.     

The internal friction of glasses

Basic fundamentals of the elastic behaviour of a standard linear solid and the internal friction technique based on this model are briefly described. The internal friction (Q ^–1) caused by various thermally activated processes in vitreous solids are reviewed for several glass compositions in relation to ionic mobility and other relevant properties. Similar relaxation mechanisms characterize many vitreous solids. The relaxation of alkali ions is essentially independent of the glass network former and has an activation energy of 15 to 25 kcal mol^–1. Other processes like the interaction of oxygen ions and protons, alkali ions and protons, mixed-alkali ion interaction and the motion of single bonded oxygen ions have an activation energy of 30 to 40 kcal mol^–1. The activation energy for relaxation of the glass network is 100 to 120 kcal mol^–1.     

Biodegradation of oxo-alcohol ethoxylates in the continuous flow activated sludge simulation test

Biodegradation of two alpha-methyl branched oxo-alcohol ethoxylates (OAE) of different polydispersity: LIAL 125/14 BRD (LIALB) (broad M.W. distribution) and LIAL 125/14 NRD (LIALN) (narrow M.W. distribution), both having an average of 14 oxyethylene subunits (EO) and a C(12-15) alkyl moiety were tested under the continuous flow activated sludge conditions of the classical Husmann plant. Primary biodegradation and concentration of metabolites: free oxo-alcohol fraction (FOA) and poly(ethylene glycols) (PEG), were measured. PEG were divided into two fractions: short-chained PEG (PEGshch) (1-4 EO) and long-chained PEG (PEGlch) (>4 EO). The indirect tensammetric technique combined with an adequate separation was used for analysis. Central fission was found to be a highly dominating pathway, as is the case with fatty alcohol ethoxylates. OAE are highly primarily biodegraded (above 95%). High concentrations of FOA and PEG are formed. Once formed the PEGlch are further fragmented into the PEGshch. Free alcohol fraction compounds are biodegraded sooner when alkyl moiety is shorter. OAE polydispersity has an influence on the kinetics of biodegradation; PEG formed from LIALN are biodegraded slower and to a lower degree than those from LIALB.     

Performance analysis of multiple-input multiple-output system for wireless network in an office room

Multiple-input multiple-output (MIMO) systems offer a greater capacity in comparison with systems based on single antennas. They are particularly suitable for an indoor environment. In this paper, the performance of the MIMO system (4,4) with 1 transmitter and 32 receivers, situated in an office room, was investigated. For calculations, the ray-tracing algorithm was used. With an optimal configuration, the achieved capacity was more than 3 times greater than the capacity for the system (1,1). The results were almost independent of the dielectric constant of the room walls, floor, and ceiling.     

Finite-Element Model for Failure Study of Two-Dimensional Triaxially Braided Composite

A new three-dimensional finite-element model of two-dimensional, triaxially braided composites is presented in this paper. This mesoscale modeling technique is used to examine and predict the deformation and damage observed in tests of straight-sided specimens. A unit cell-based approach is used to consider the braiding architecture and the mechanical properties of the fiber tows, the matrix, and the fiber tow-matrix interface. A 0°/±60° braiding configuration has been investigated by conducting static finite-element analyses. Failure initiation and progressive degradation has been simulated in the fiber tows by using the Hashin failure criteria and a damage evolution law. The fiber tow-matrix interface was modeled by using a cohesive zone approach to capture any fiber-matrix debonding. By comparing the analytical results with those obtained experimentally, the applicability of the developed model was assessed and the failure process was investigated.     

Congener-specific tissue distribution of aroclor 1254 and a highly chlorinated environmental PCB mixture in rats

Polychlorinated biphenyl (PCB) mixtures were synthesized and marketed in Eastern European countries, but little is known abouttheir composition, distribution, ortoxicity. PCB-contaminated soil from the former production site of the Polish PCB mixture Chlorofen was collected, and the PCBs were extracted. An in vivo study was performed to investigate the PCB tissue distribution and biochemical effects of this soil extract in immature male Sprague-Dawley rats. Rats were administered 0.05 mmol/kg soil-extracted PCBs or Aroclor 1254 and sacrificed 7 days later, and congener-specific PCB profiles in selected tissues were determined. Distribution of SigmaPCBs (sum of 120 congeners) in tissues was primarily a function of lipid content of the tissues, except for the spleen, which retained more PCB than other tissues. Multivariate analysis of the PCB congener data showed that (a) congener profiles in tissues had changed, as compared to the parent mixture; (b) disposition and redistribution of individual congeners in vivo differed between both mixtures; and (c) more highly chlorinated congeners were retained in the spleens of both treatment groups. Differences in the induction of cytochrome P-450 1A and 2B subfamilies reflected the homologue composition of the respective mixtures and predict a different toxicity profile for Chlorofen than for Aroclor 1254.