Thermosonic wire bonding is a common fabrication process for connecting devices in electronic packaging. However, when the free air ball (FAB) is compressed onto the I/O pad of the chip during bonding procedure, chip cracking may occur if the contact pressure is too large. This study proposes an effective simulation technique that can predict the wire ball geometry after bonding in an accurate range. The contact force obtained in the simulation can be used for possible die cracking behavior evaluation. The simulation in this study used the explicit time integration scheme to deal with the time marching problem, and the second-order precision arbitrary Lagrangian-Eulerian (ALE) algorithm was used to deal with the large deformation of the wire ball during the bonding process. In addition, the equilibrium smoothing algorithm in LS-DYNA can make the contact behavior and geometry of the bonding wire almost the same as the experiment, which can also significantly reduce the distortion of the mesh geometry after remeshing.

Litter size has a great impact on the profit of swine producers. Uterine development is an important determinant of reproduction efficiency and could hence affect litter size. Chinese Erhualian pig is one of the most prolific breeds in the world, even though large phenotypic variation in litter size was observed within Erhualian sows. To dissect the genetic basis of the phenotypic variation, we herein conducted genome-wide association studies for total number born and number born alive (NBA) of Erhualian sows. In total, one significant single nucleotide polymorphism (SNP) (P<1.78e−06) and 11 suggestive SNPs (P<3.57e−05) were identified on 10 chromosomes, confirming seven previously reported quantitative trait loci (QTL) and uncovering six QTL for litter size or uterus length. One locus on Sus scrofa chromosome (SSC) 13 (79.28 to 90.43 Mb) harbored a cluster of suggestive SNPs associated with multiparous NBA. The SNP (rs81447100) within this region was confirmed to be significantly (P<0.05) associated with litter size in Erhualian (n=313), Sutai (n=173) and Yorkshire (n=488) populations. Retinol binding protein 2 and retinol binding protein 1 functionally related to the development of uterus were located in a region of 2 Mb around rs81447100. Moreover, four genes related to embryo implantation and development were also detected around other significant SNPs. Taken together, our findings provide a potential marker (rs81447100) for the genetic improvement of litter size not only in Chinese Erhualian pigs but also in European commercial pig breeds like Yorkshire, and would facilitate the final identification of causative variant(s) underlying the effect of SSC13 QTL on litter size.

Over the past 8 years, human enteroviruses (HEVs) have caused 27 227 cases of hand, foot and mouth disease (HFMD) in Xiamen, including 99 severe cases and six deaths. We aimed to explore the molecular epidemiology of HFMD in Xiamen to inform the development of diagnostic assays, vaccines and other interventions. From January 2009 to September 2015, 5866 samples from sentinel hospitals were tested using nested reverse transcription PCR that targeted the HEV 5′ untranslated region and viral protein 1 region. Of these samples, 4290 were tested positive for HEV and the amplicons were sequenced and genotyped. Twenty-two genotypes were identified. Enterovirus 71 (EV71) and coxsackieviruses A16, A6 and A10 (CA16, CA6 and CA10) were the most common genotypes, and there were no changes in the predominant lineages of these genotypes. EV71 became the most predominant genotype every 2 years. From 2013, CA6 replaced CA16 as one of the two most common genotypes. The results demonstrate the vast diversity of HFMD pathogens, and that minor genotypes are able to replace major genotypes. We recommend carrying-out long-term monitoring of the full spectrum of HFMD pathogens, which could facilitate epidemic prediction and the development of diagnostic assays and vaccines.

Presently, physical limitations are restricting the development of the microelectronic industry driven by Moore's law. To achieve high-performance, small form factor, and lightweight applications, new electronic packaging methods have exceeded Moore's law. This research proposes a double-chip stacking structure in an embedded fan-out wafer-level packaging with double-sided interconnections. The overall reliability of the solder joints and redistributed lines is assessed through finite element analysis. The application of soft lamination material and selection of a carrier material whose coefficient of thermal expansion (CTE) is close to that of the printed circuit board can effectively enhance the reliability of solder joints over more than 1,000 cycles. A trace/pad junction whose direction is parallel to the major direction of the CTE mismatch is recommended, and the curved portion of trace lines can absorb the expansion of metal lines and filler material. Design-on-simulation methodology is necessary to develop novel packaging structures in the electronic packaging industry.

Three-dimensional integrated circuit packages with through-silicon vias (TSVs) provide a good solution to the integration of different chips and help achieve high performance. The signals are transmitted to different layers directly through the vias, thereby enabling the high performance of the chips. Plasma-enhanced chemical vapor-deposited SiO2, polyimide, and benzo-cyclo-butene are commonly used as the passivation layer for three-dimensional packages. In the 3D stacked chips, mismatch of the coefficient of thermal expansion between the passivation material and silicon will generate thermal/mechanical stress in the metal trace and the stress affects the behavior of electromigration. However, few studies have examined the relationship among the external mechanical stress and critical product of electromigration. In the present study, external stress is applied to the aluminum thin film by a four-point bending equipment. In order to apply higher external stress in the aluminum thin film, the fracture strength of the silicon substrate should be improved. Reduces the edge chipping of the test sample is a key factor for improving the fracture strength of the silicon substrate and a special cutting approach is employed to obtain higher silicon strength. A two-step cutting method is applied to reduce front side chipping and also a dicing before grinding approachis adopted to reduce backside chipping, the above-mentioned technology can enable more than 275MPa of external stress on the aluminum thin film and can make the critical length effect more visible. The residual stress of the aluminum thin film is at stress-free state after annealing at 300°C for 10h. The critical product is found to be reduced from 1,294A/cm to 1,281A/cm when 120MPa of mechanical tensile stress is applied. It increased to 1,315A/cm under 120MPa of mechanical compressive stress. Clearly, electromigration behavior is enhanced by tensile stress and decreased by compressive stress. In the current research, a modified equation for Blech condition is proposed with a stress-dependent effective charge number, the effective charge number increased when tensile stress was applied and decreased when compressive stress was applied.

While rabies is a significant public health concern in China, the epidemiology of animal rabies in the north and northwest border provinces remains unknown. From February 2013 to March 2014, seven outbreaks of domestic animal rabies caused by wild carnivores in Xinjiang (XJ) and Inner Mongolia (IM) Autonomous Regions, China were reported and diagnosed in brain samples of infected animals by the fluorescent antibody test (FAT) and RT–PCR. Ten field rabies viruses were obtained. Sequence comparison and phylogenetic analysis based on the complete N gene (1353 bp) amplified directly from the original brain tissues showed that these ten strains were steppe-type viruses, closely related to strains reported in Russia and Mongolia. None had been identified previously in China. The viruses from XJ and IM clustered separately into two lineages showing their different geographical distribution. This study emphasizes the importance of wildlife surveillance and of cross-departmental cooperation in the control of transboundary rabies transmission.

Annual H3N2 subtype influenza outbreaks in Guangdong, China are a severe public health issue and require ongoing monitoring of emerging viral variants. The variation and evolution of haemagglutinin (HA) and neuraminidase (NA) genes of influenza isolates from Guangdong during 2007–2011 and others from GenBank were analysed using Lasergene 7.1 and MEGA 5.05, and serological analysis of antigens was determined by haemagglutination inhibition (HI). Susceptibility to antiviral drugs was correlated with genetic mutations. Phylogenetic analysis and alignment of HA and NA genes were performed on 18 Guangdong isolates and 26 global reference strains. The non-synonymous (dN) evolutionary rate of HA1 was 3·13 times that of HA2. Compared with the A/Perth/16/2009 vaccine HA gene, homologies of Guangdong isolates were between 98·8–99·7% and 98·0–98·4% in 2009 and 2010, respectively. Amino-acid substitutions were found in five epitopes of HA1 from Guangdong isolates between 2007 and 2011, especially in epitopes B (N160K) and D (K174R/N). The K189E/N/Q and T228A mutations in the receptor-binding site (RBS) occurred in the 2010 strains, which affected the antigenicity of HA1. The antigenicity of the epidemic H3N2 isolates in 2010 was somewhat different from that of A/Perth/16/2009. The Guangdong H3N2 isolates were determined to be oseltamivir-resistant with IC50 of 0·396±0·085 nmol/l (n=17) and zanamivir-resistant with IC50 of 0·477±0·149 nmol/l (n=18). Variations were present in epitopes B and D, two sites in the RBS and two glycosylation sites in the Guangdong H3N2 HA1 gene. The majority of the Guangdong H3N2 isolates were sensitive to oseltamivir and zanamivir. Compared to the World Health Organization 2012 vaccine strains, Guangdong H3N2 strains varied genetically and antigenically to some degree.

We present the initial results of a spectral line survey of L1157 B1 with the Nobeyama 45 m telescope. So far, we have covered the frequencey range of 13.7 GHz (82.0–94.5 GHz and 96.3–97.5 GHz), and have detected 22 species including CH3CHO, HCOOH, HCOOCH3, HNCO, NH2CHO, CH3CN, and CCS. We have also detected the line of CH2DOH. These results demonstrate rich chemistry in this shocked region, which would mainly originate from evaporation of ice mantles by means of shocks.

The effective sampling area of a monitoring station, α, was calculated for several Coptotermes formosanus Shiraki colonies in Broward County, Florida, USA. A simple mark–recapture protocol provided data on termite station catch within a foraging range of a colony. Average recapture probability was 0.005 close to the releae point (< 5 m) and declined to 0.0008 at a distance of 51 to 60 m. The relation between the log % termites recaptured was fitted with log distance, to determine P(x), the average proportion of captured termites that started at distance x from the release point. The effective sampling area was estimated by using P(x) and the equation, α 2 π∫{ x P(x)} dx. Integrating this equation, an average estimate α that ranged from 0.607 to 14.5 m2 was obtained. Factors influencing the variation of α among the colonies are discussed. The effective sampling area estimated should be taken as a reliable estimator that translates subterranean termite catches into termite population density.

During the early stages of the development of termite baits, dyed paper was placed in specified feeding stations to ascertain whether a slow-acting toxicant could be placed in a few bait stations to be delivered to the entire colony members of the Formosan subterranean termite, Coptotermes formosanus Shiraki. Feeding frequency data, as measured by the dye concentration in individual termites, suggested the absence of feeding site fidelity. However, these results were often misinterpreted as random movement of termites that were marked and released for population estimate studies, or the random search of food in soil by subterranean termites. A computer simulation program was constructed to re-examine this feeding frequency data, and confirmed the earlier conclusion that the lack of feeding site fidelity was the most likely explanation for the data.

The mark–recapture technique is currently being used by many termite researchers. Here it's two uses are explained and disentangled. Use 1 is mapping the geographical location of the colony and use 2 is estimating the number of termites in the colony. Use 2 is controversial because the accuracy of the estimates has been widely questioned. In this article, it is explained that use 1 is not controversial and that use 1 (not use 2) is the criterion that is currently being used for evaluating the efficacy of termite baits.

Thin films of Pb(Sc1/2Ta1/2)O3 (PST) were fabricated using an optimized chemical solution deposition procedure involving the de-hydration of scandium acetate and the addition of up to 30% excess lead in solution. The choice of substrate was found to impact the thermal induced stress in the films as confirmed by wafer bending and in-plane grazing angle x-ray diffraction measurements. The presence of either a compressive or a tensile in-plane stress led to a reduction in the temperature of the dielectric maximum, whereas the value of the dielectric maximum remained relatively unchanged; its value reduced by an order of magnitude compared with ceramic samples. It is concluded that mechanical stress alone is not the sole factor in the reduction of PST thin film permittivity. Microstructural features resulting from processing induced defects or an incomplete transformation to the relaxor state may be responsible for this commonly observed phenomenon.

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

Muscle phenotype is central to the quantity and quality of meat production. Quantity is a function of muscle hyperplasia and hypertrophy. Hyperplastic growth in utero is a function of myocyte proliferation and differentiation, and post-natal growth is primarily the result of hypertrophy of existing and replaced muscle fibres. Quality is a more complex trait and is assessed by a variety of objective and subjective parameters, such as colour, pH, tenderness, odour and juiciness. It is increasingly evident that fibre type composition is a major determinant of meat quality. Favourable meat traits, such as tenderness, have been found to associate with the greater abundance of oxidative fibres. Therefore, knowledge of the molecular events that affect hypertrophy (or atrophy), hyperplasia (or hypoplasia), and fibre type-specific expression is of fundamental agricultural importance.

We present a statistical investigation of shear motion of the EUV footpoints in two-ribbon solar flares, using the high spatial resolution data obtained in 1998–2005 by the Transition Region and Coronal Explorer (TRACE). In this study we have selected 50 well-observed X- and M- class two-ribbon flares. Our preliminary results are: a) 86% (43 out of 50) of these flares show shear change of footpoints and ribbon separation; b) there is no obvious ribbon separation in those 7 flares which have no shear change of the conjugate footpoints; c) in most events, the cessation of shear change is 0–2 minutes earlier than the end of the impulsive phase.

Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005

Single crystalline ZnSe nanowires were fabricated on GaAs substrates by molecular beam epitaxy technique via Au-catalyzed vapor-liquid-solid reaction. The nucleation and initial growth of the nanowires were investigated by high-resolution transmission electron microscopy. It was revealed that Au catalysts initially reacted with the substrate forming binary AuGa2 alloy droplets. The sizes of the catalysts determined the growth direction of ZnSe nanowires. A model based on the surface energies of the nanowire nuclei was proposed to explain the size dependence of growth direction for ZnSe nanowires.