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The interfacial reactions in Ni/Sn-xZn/Cu sandwich couples which were reflowed at 270°C for 1 h and then aged at 160°C for 1–1000 h were investigated. When the 1000-μm-thick Sn-Zn alloy reacted with Ni and Cu in this couple, the results indicated that the (Ni, Cu)3Sn4, (Ni, Cu)5Zn21, and Ni5Zn21 phases were formed at Sn-1Zn/Ni, Sn-5Zn/Ni, and Sn-9Zn/Ni interfaces for 1 h reflowing, respectively. After 1000 h aging, each intermetallic compound (IMC) was converted to (Cu, Ni, Zn)6Sn5, (Ni, Cu, Sn)5Zn21/Ni5Zn21, and Ni5Zn21 (two layers) phases in the related couples. On the Cu side, the Cu6Sn5 phase in the Sn-1Zn/Cu interface and the Cu5Zn8 phase in the Sn-5Zn/Cu and Sn-9Zn/Cu interfaces were observed when the couple was reflowed at 270°C for 1 h. After 100 h aging, the (Cu, Ni, Zn)6Sn5, Cu5Zn8/(Cu, Zn)6Sn5, and Cu5Zn8 phases were formed at the Sn-1Zn/Cu, Sn-5Zn/Cu and Sn-9Zn/Cu interfaces. When the Sn-Zn alloy thickness was decreased to 500 μm, the (Cu, Ni, Zn)6Sn5 phase at the Sn-1Zn/Ni interface and the (Ni, Cu, Sn)5Zn21 phase at the Sn-5Zn/Ni and Sn-9Zn/Ni interfaces were observed after 1 h reflowing. When the couple was aged at 160°C for 1000 h, each IMC was converted to (Cu, Ni, Zn)6Sn5 and Cu5Zn8/(Cu, Ni, Sn)Zn/Ni5Zn21 phases at the Sn-1Zn/Ni and Sn-(5, 9)Zn/Ni interfaces. (Cu, Ni, Zn)6Sn5 and Cu5Zn8 were, respectively, formed at the Sn-1Zn/Cu and Sn-(5, 9)Zn/Cu interfaces for 1 h reflowing. After 100 h aging, the IMCs were converted to (Cu, Ni, Zn)6Sn5 and Cu5Zn8/(Cu, Zn)6Sn5 phases. This current study reveals that the IMC formation in Ni/(Sn-xZn)/Cu sandwich couples are very sensitive to the Zn concentration and thickness in Sn-xZn alloys.

Aging and Cu concentration effects on the interfacial reactions between Sn–9 wt%Zn– x wt%Cu (SZ– x Cu) alloys and the Au substrate were investigated in this study. The Au 3 Zn 7 /AuZn 2 /AuZn and Au 3 Zn 7 /AuZn phases were formed in the SZ/Au and SZ–1Cu/Au couples aged at 160 °C for 24 h. Only the AuSn phase was found in the SZ–4Cu/Au couple aged at 160 °C for 24 h. When the aging time was extended to 800 h the Sn atoms became the dominant diffusion element. Binary Au–Sn phases and the metastable Au–Zn–Sn ternary phase were formed at the interface in the SZ– x Cu couples when the Cu content was 1–4 wt%. When the Cu content was increased to 7–10 wt% AuSn and (Cu, Au)Sn phases were observed at the alloy/Au interface aged at 160 °C for 24 h. After 800-h heat treatment the SZ– x Cu systems were transformed completely into the Cu–Sn/Au systems. The (Cu, Au)SnAuSn and Cu 6 Sn 5 /AuSn were formed in the SZ–7Cu/Au and SZ–10Cu/Au couples. The results indicate that the evolution of intermetallic compounds (IMCs) was very sensitive to the Cu concentration in the SZ solders and the heat treatment period.

Microcystis, a genus of potentially harmful cyanobacteria, is known to proliferate in stratified freshwaters due to its capability to change cell density and regulate buoyancy. In this study, a trajectory model was developed to simulate the cell density change and spatial distribution of Microcystis cells with nonuniform colony sizes. Simulations showed that larger colonies migrate to the near-surface water layer during the night to effectively capture irradiation and become heavy enough to sink during daytime. Smaller-sized colonies instead took a longer time to get to the surface. Simulation of the diurnally varying Microcystis population profile matched the observed pattern in the field when the radii of the multisized colonies were in a beta distribution. This modeling approach is able to take into account the history of cells by keeping track of their positions and properties, such as cell density and the sizes of colonies. It also serves as the basis for further developmental modeling of phytoplanktons that are forming colonies and changing buoyancy.

With a relatively low liquidus temperature, the eutectic Sn-Zn alloy is suitable replacement for conventional eutectic Sn-Pb solder in the electronic industry. One of the most important materials as a lead-frame is Fe-42Ni alloy (Alloy 42) in the microelectronic packaging. The Sn-Fe-Zn ternary phase diagram is a powerful and useful tool to understand the interfacial reactions between Sn-Zn alloy and Alloy 42 substrate (Fe-rich alloy). The isothermal section of the Sn-Fe-Zn ternary system was experimentally investigated at 270oC in this study. Ternary Sn-Fe-Zn alloys were prepared and annealed at 270 oC to determine the isothermal section of the Sn-Fe-Zn ternary system. The experimental results revealed that no ternary intermetallic compound was formed, and noticeable Zn solubility was observed in the FeSn2 phase. The isothermal section of the Sn-Fe-Zn ternary system consists of nine single-phase areas, thirteen two-phase areas, and seven tie-triangles at 270 oC

The interfacial reactions of Sn-xZn/Au couples aged at 160°C were investigated. When the Zn content was 3 wt.%, binary Au-Sn intermetallic compounds (IMCs) and ternary Au-Sn-Zn phase were formed at the interface. Both binary Au-Sn and Au-Zn and ternary Au-Sn-Zn IMCs were formed at the Sn-5Zn/Au interface. When the Zn content was 7 wt.%, Sn-xZn/Au couples were completely transformed into an Au-Zn system. Based on ln d = nln t + ln k, where d is IMC thickness, t is aging time, and n is the growth exponent, the n value of Sn-xZn/Au (x < 5 wt.%) couples was between 0.25 and 0.33. Sn-xZn/Au (x = 7 wt.% to 15 wt.%) couples also had similar results when the aging times were 144 h. The n value of the Sn-50Zn/Au couple was 0.5, and the reaction mechanism was diffusion controlled. The n value for the Sn-90Zn/Au couple was 0.19. The results indicated that adding Zn to Sn-Zn alloys would change the reaction system from the Au-Sn system into the Au-Zn system.

Pets, including reptiles, have been shown to be a source of Salmonella infection in humans. Due to increasing popularity and variety of exotic reptiles as pets in recent years, more human clinical cases of reptile-associated Salmonella infection have been identified. However, limited information is available with regard to serotypes in different reptiles (turtles, snakes, and lizards) and antimicrobial resistance of Salmonella in pet reptiles. The current study was thus conducted to determine the prevalence of Salmonella colonization in pet reptiles. Salmonella organisms were isolated from 30.9% of 476 reptiles investigated. The isolation prevalences were 69.7% (23/33), 62.8% (27/43), and 24.3% (97/400) in snakes, lizards, and turtles, respectively. A total of 44 different Salmonella serovars were identified. Compared with S. Heron, Bredeney, Treforest, and 4,[5],12:i:-, S. Typhimurium isolates were resistant to many antimicrobials tested, and notably 61.1% of the isolates were resistant to cephalothin. The results indicated that raising reptiles as pets could be a possible source of Salmonella infection in humans, particularly zoonotic Salmonella serovars such as S. Typhimurium that may be resistant to antimicrobials.

An increasing number of Bartonella species originally isolated from small mammals have been identified as emerging human pathogens. During an investigation of Bartonella infection in rodent populations carried out in Taiwan in 2006, a total of 58 rodents were tested. It was determined that 10.3 % (6/58) of the animals were Bartonella bacteraemic. After PCR/RFLP analysis, four isolates were identified as Bartonella elizabethae and one isolate as Bartonella tribocorum. However, there was one specific isolate with an unrecognized PCR/RFLP pattern. After further sequence and phylogenetic analyses of the gltA, ftsZ and rpoB genes, and the 16S–23S rRNA intergenic spacer region, the results indicated that this specific isolate from Rattus norvegicus was closely related to human pathogenic ‘Bartonella rochalimae’. Further studies need to be conducted to evaluate whether this rodent species could be a reservoir for ‘B. rochalimae’.

G protein−coupled receptors (GPCRs) regulate facets of growth, development, and environmental sensing in eukaryotes, including filamentous fungi. The largest predicted GPCR class in these organisms is the Pth11-related, with members similar to a protein required for disease in the plant pathogen Magnaporthe oryzae. However, the Pth11-related class has not been functionally studied in any filamentous fungal species. Here, we analyze phenotypes in available mutants for 36 GPCR genes, including 20 Pth11-related, in the model filamentous fungus Neurospora crassa. We also investigate patterns of gene expression for all 43 predicted GPCR genes in available datasets. A total of 17 mutants (47%) possessed at least one growth or developmental phenotype. We identified 18 mutants (56%) with chemical sensitivity or nutritional phenotypes (11 uniquely), bringing the total number of mutants with at least one defect to 28 (78%), including 15 mutants (75%) in the Pth11-related class. Gene expression trends for GPCR genes correlated with the phenotypes observed for many mutants and also suggested overlapping functions for several groups of co-transcribed genes. Several members of the Pth11-related class have phenotypes and/or are differentially expressed on cellulose, suggesting a possible role for this gene family in plant cell wall sensing or utilization.

Following the groundbreaking ethnographic work of Heath (1983), Cruickshank's book, Teenagers, Literacy, and School, examines the gaps between literacy practices at home and school. By studying a g...

Infection with Salmonella enterica serovar Choleraesuis (S. Choleraesuis) in humans can be considered as an endemic disease in certain regions of Taiwan, and the number of cases has increased in recent years. The goal of the case-control study discussed in this article was to identify the possible demographic and environmental risk factors associated with S. Choleraesuis infection in Taiwan. During the period of December 2005 to March 2007, the case-control study was conducted in human patients with Salmonella infection from two medical centers. Structured questionnaires were applied to collect information of relevant risk factors after interviewing 13 culture-confirmed S. Choleraesuis cases and 84 controls with other Salmonella serotype infection. After evaluation by univariate and multivariate statistical models, the results suggested that consumption of groundwater could be an independent risk factor associated with S. Choleraesuis in Taiwan. Therefore, appropriate health education needs to be conducted especially in areas where groundwater is used.

This study shows the influence of micro-porous layers (MPLs) structure on the performance of a proton exchange membrane fuel cell. Four MPLs were prepared with different carbon loadings. The various MPLs were prepared with different degrees of carbon loading on the surface of a gas diffusion layer (GDL), and their resistance and performance were characterized. With the same test conditions, the multi micro-porous layers had a higher current density than GDL. At 0.7 V, performance with 15 layers of MPLs in the gas diffusion layer increased by approximately 47% compared with GDL. Loading degree had a major effect on performance.

Summary form only given. In recently published papers, we have successfully demonstrated that high efficiency narrow-band acoustooptic tunable reflectors (acoustooptic superlattice modulator (AOSLM)) using a uniform fiber Bragg grating can be achieved by improving overlap between the acoustic waves and optic waves by a HF etching technique. AOSLM which bases on induced coupling between the forward and backward propagating Bloch modes in the grating is dramatically different from all previously reported acoustooptic fiber devices, which depend on co-propagating intermodal coupling. In an AOSLM, the coupled wave propagates in the opposite direction to the original optic wave and therefore can be taken out by a circulator and it can also have subnanometer bandwidth. In this paper, we used Sinc-sampled gratings to further verify the AOSLM performances and to add more switchable channels. Four wavelength channels are simultaneously switched in our implementation with an application of an acoustic wave along the fiber axis. This is the consequence of added side-bands in spatial frequency formed in a periodically phase-modulated Bragg grating. The number of switchable channels can be further increased with an increase in the number of channels in the original Sinc-sampled grating.

We present a recasting of corner detection to a problem in statistical pattern recognition which we then address with a simple feedforward neural network. The resulting classifier is a robust, threshold-free corner detector which labels with (approximate) Bayesian posterior probabilities; this is in contrast to conventional feature detectors which produce binary labels contingent on a heuristically set threshold. We have generated the training data for our classifier using a grey-level model of the corner feature which permits sampling of the pattern space at arbitrary density as well as providing a validation set to assess the classifier generalisation. Results are presented for real images and the robustness illustrated over a well-known state-of-the-art conventional corner detector.

In this paper we report the results of Bayesian labelling corner features in images with a modular neural network trained on data from a grey-level model of corners. Since adequate learning the whole mapping by a single network is problematic we present a bootstrapping procedure to partition data across modules. Results on real images are presented together with comparisons with the same labelling task performed by a monolithic network.

Particles from several types of sources in central Taiwan were sampled and analyzed to obtain representative source profiles for use in receptor modeling. The sources studied include field soil, paved road dust, unpaved road dust, coastal sand, river sand, and aerosols generated by burning of agricultural wastes. The agricultural wastes studied include rice straw, corn stalk, and sugarcane leaves. All the samples were analyzed for 20 elements by an X-ray fluorescence spectrometer. The mass percentages of elemental carbon (EC) and organic carbon (OC) in particle samples were determined by an elemental analyzer. For particles obtained from resupension of soils and dusts, the mass percentage of the fine fraction is in the range of 40 to 61 %. The abundant elements in the coarse fraction are Si, Al, Fe, K., and Ca. In the coarse fraction, only paved road dust contains OC. The abundant species in the fine fraction are OC, Si, Fe, Al, K, and Ca. Particles generated by combustion of agricultural wastes are mainl...