Fabrication of Single-Crystal α-Al2O3 Nanorods by Displacement Reactions

Nanometer-sized Al₂O₃ rods are fabricated by sintering a powder mixture of Al and SiO₂. The sintered product is leached in HF–HNO₃ solution, followed by rinsing and washing before the nanorods are collected. The yield of the product is about 50 wt%. Transmission electron microscopy reveals that these rods are 1 to 2 μm long and have a diameter of 20 to 100 nm, while electron diffraction confirms that these rods are single crystals of α-Al₂O₃. It is observed that these rods have either round or slightly sharp tips, which is different from those having droplet-like tips that are usually found in products fabricated by catalytic reactions.     

Application of the transmission line equivalent circuit model to the analysis of the PN junction admittance under d.c. bias

Exact non-equilibrium one-energy-level numerical solutions of the admittance of a p+n junction are obtained from the nonuniform transmission line equivalent circuit model. Capacitance and conductance curves for equilibrium and reverse-biased gold-doped silicon diode are calculated using experimental values of emission and capture rates. Comparisons between theoretical and experimental frequency dependences of the admittance using new experimental capture rates show good agreements over a wide range of reverse bias.     

Epitaxy-Like Protective Layers for High-Performance Low-Cost Au/Pd/Ni Preplated Cu Alloy Leadframes

In this paper, we report the performance, the crystal microstructure, and defects of Au/Pd/Ni/Cu preplated lead frames (PPF). The wire pull test, the solderability test, and high-resolution transmission electron microscopy (HRTEM) are employed to characterize the PPFs in order to understand the relationship between performance and microstructure. The electroplated PPFs are composed of Au (3 nm)/Pd (5 to 15 nm)/Ni (0.7 mum)/Cu substrate. We optimize the electroplating profile and determine the minimum thickness of the Pd layer with the PPF performance satisfying the industry standards. Further increasing the Pd layer thickness beyond the critical thickness will not enhance the performance more, but increase the product cost. With the optimized electroplating profile, the electroplated Au layer is epitaxially deposited on the Pd layer, and so does the Pd layer on the Ni layer. The interface between the Au and Pd layers is in general coherent in spite of the about 4.8% mismatch strain between the Au and Pd lattices because the Au layer thickness is only 3 nm small. Misfit dislocations and nanotwins are present at the interface between the Pd and Ni layers, which are generated to release the about 10.4% misfit strain between the Pd and Ni lattices     

A web search-centric approach to recommender systems with URLs as minimal user contexts

In service-oriented computing, a recommender system can be wrapped as a web service with machine-readable interface. However, owing to the cross-organizational privacy issue, the internal dataset of an organization is seldom exposed to external services. In this paper, we propose a higher level recommender strategy INSERT that guides the underlying external universal recommender to suggest a set of indexes. INSERT then matches the title of each top-ranked index entry with the domain-specific keywords in the organization's internal dataset, and further directs the universal recommender to verify the popularity of such matching. INSERT finally makes recommendation based on the verification results. INSERT also employs URLs taken from a client as user contexts, which is challenging because URLs contain little content. Our experiment shows that this strategy is feasible and effective.     

Physical parameters effect on ozone-initiated formation of indoor secondary organic aerosols with emissions from cleaning products

The effect of air exchange rate (ACH), temperature (T), and relative humidity (RH) on the formation of indoor secondary organic aerosols (SOAs) through ozonolysis of biogenic organic compounds (BVOCs) emitted from floor cleaner was investigated in this study. The total particle count (with D(p) of 6-225 nm) was up to 1.2 × 10(3)#cm(-3) with ACH of 1.08 h(-1), and it became much more significant with ACH of 0.36 h(-1) (1.1 × 10(4)#cm(-3)). This suggests that a higher ventilation rate can effectively dilute indoor BVOCs, resulting in a less ultrafine particle formation. The total particle count increased when temperature changed from 15 to 23 °C but it decreased when the temperature further increased to 30 °C. It could be explained that high temperature restrained the condensation of formed semi-volatile compounds resulting in low yields of SOAs. When the RH was at 50% and 80%, SOA formation (1.1-1.2 × 10(4)#cm(-3)) was the more efficient compared with that at RH of 30% (5.9 × 10(3)#cm(-3)), suggesting higher RH facilitating the initial nucleation processes. Oxidation generated secondary carbonyl compounds were also quantified. Acetone was the most abundant carbonyl compound. The formation mechanisms of formaldehyde and acetone were proposed.     

Non-Invasive Brain Stimulation Effects on Biomarkers of Tryptophan Metabolism: A Scoping Review and Meta-Analysis

Abnormal activation of the kynurenine and serotonin pathways of tryptophan metabolism is linked to a host of neuropsychiatric disorders. Concurrently, noninvasive brain stimulation (NIBS) techniques demonstrate high therapeutic efficacy across neuropsychiatric disorders, with indications for modulated neuroplasticity underlying such effects. We therefore conducted a scoping review with meta-analysis of eligible studies, conforming with the PRISMA statement, by searching the PubMed and Web of Science databases for clinical and preclinical studies that report the effects of NIBS on biomarkers of tryptophan metabolism. NIBS techniques reviewed were electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS). Of the 564 search results, 65 studies were included with publications dating back to 1971 until 2022. The Robust Bayesian Meta-Analysis on clinical studies and qualitative analysis identified general null effects by NIBS on biomarkers of tryptophan metabolism, but moderate evidence for TMS effects on elevating serum serotonin levels. We cannot interpret this as evidence for or against the effects of NIBS on these biomarkers, as there exists several confounding methodological differences in this literature. Future controlled studies are needed to elucidate the effects of NIBS on biomarkers of tryptophan metabolism, an under-investigated question with substantial implications to clinical research and practice.     

Counseling style preference of international students.

Examined, with a single-S research design, the counseling-style preference of 6 international clients and 1 White-American client within and across 4 counseling sessions. All clients first listened to an audiotape (analog) counseling session containing a problem-solving approach and a client-centered approach and rated both approaches. The clients then rated these 2 counseling styles in actual counseling sessions. In contrast to past research findings, no overall preference was found for either approach. Preferences for a particular counseling style also changed from session to session. In addition, preferences exhibited during the analog portion of the study were often different from those expressed during the actual counseling sessions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Complete classification of finite-dimensional estimation algebras of maximal rank

The idea of using estimation algebras to construct finite-dimensional non-linear filters was first proposed by Brockett and Clark, and Mitter independently. In his famous talk at the International Congress of Mathematics in 1983, Brockett proposed to classify all finite-dimensional estimation algebras. In this paper we explain why the theory of estimation algebras plays an important role in non-linear filtering. We show how to use the Wei-Norman approach to construct finite-dimensional filters from finite-dimensional estimation algebras. We survey some results in estimation algebras after 1984. We give a self-contained proof of complete classification of finite-dimensional estimation algebras of maximal rank in one place. The proof given here is simpler than those proofs scattered in several papers. This provides the readers with a complete coherent view of the important topic of the classification of finite-dimensional estimation algebras.     

Nanocomposite of chitosan and silver oxide and its antibacterial property

An aqueous emulsion of chitosan nanoparticles encapsulating silver oxide is prepared from silver nitrate and chitosan. The nanoparticles are positively charged with an average diameter of 300 nm. The dried particle has a spherical shape with a 100 nm diameter. The emulsion is applied onto cotton and delivers a durable antibacterial activity against S. aureus and E. coli, after 20 washings. The coefficient of friction of the treated fabric is similar to that of the untreated cotton fabric. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

The free-radically prepared copolymers of acrylonitrile with furfuryl alcohol and similar furan derivatives

The preparation of copolymers of acrylonitrile with furfuryl alcohol, furfuryl acetate, bis-2,5-hydroxymethyl furan and bis-2,5-acetoxymethyl furan by a free radical reaction is described. Proton and ¹³C-n.m.r. spectroscopy has been used to characterise the residues that form from the furan monomers by the addition reaction. The residues produced by a 5,4-addition to the furfuryl alcohol ring or by 2,3-addition to the 2,5-dihydroxyfuran ring are susceptible to acid and undergo a rearrangement which removes the olefinic structure. The copolymers are decomposed to a hard, glassy carbonaceous material by heating in nitrogen in a process that has been examined by thermogravimetric analysis and elemental analysis. The copolymers prepared from furan monomers that contain a methylol group decompose more readily at a lower temperature than those which lack the group or than those in which the alcohol has been acetylated.