bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is the Heterogeneous Microstructure of SnAgCu (SAC) Solders Going to Pose a Challenge for Heterogeneous Integration?
Authors: Jiang Qian , Deshpande Abhishek , Dasgupta Abhijit 
Published: October 2017

The coarse heterogeneous microstructure of SAC alloys makes the behavior of interconnections highly sensitive to its geometric length-scale. Heterogeneous integration and the resulting increase in package complexity and miniaturization are making this scale-effect ever more important. This scale effect derives from the anisotropy of tin and the coarse multi-tiered microstructural heterogeneities in SAC solders. As a result, no two joints behave the same and every joint is unique depending on its specific microstructure. Product teams responsible for reliable heterogeneous integration have to ensure that they have adequate methods to deal with this variability.
This paper highlights the multi-tiered microstructural morphology in SAC solders due to the solidification and crystallization process. At the highest tier in the joint microstructure are individual (highly anisotropic) grains that can be 100s of microns in size. At the next lower tier the primary heterogeneity is due to individual dendrites of pro-eutectic β tin, that can have lobes as large as 10–20 microns. At the next lower tier the characteristic heterogeneity is a eutectic mix of nanoscale Ag3Sn IMC particles dispersed in a Sn matrix.
Researchers have long recognized that the grain morphology is extremely important to mechanical behavior of BGA solder joints because they are coarse-grained (i.e. there may be only a few anisotropic grains in each BGA solder joint). However, heterogeneous integration has now led to joints that are much smaller (less than 100 microns tall), thus making them of the same length-scale as individual tin dendrites within each grain. In other words, there may be just a few dendrites through the thickness of the joint. Unfortunately, very little attention has focused on SAC behavior at such a small length-scale. This study focuses on the effect of the tin-dendrite morphology on the effective behavior of SAC solder joints, using a combination of experiments and multi-tiered anisotropic models that combine dislocation nano-mechanics with composite micromechanics. The volume fraction of β-Sn dendrite within one crystal could vary from 20% to 80%, depending on the time and temperature above the liquidus temperature and the cooling rates. The effects of volume fraction and aspect ratio of Sn dendrites on the anisotropic steady-state creep rate of single crystal SAC specimen are examined. The objective of the study is to provide insights into the role that solder microstructural heterogeneity will play on package reliability in heterogeneous integration.
Prediction and Mitigation of Vertical Cracking in High-Temperature Transient Liquid Phase Sintered Joints by Thermo-Mechanical Simulation
Authors: Greve Hannes , Moeini S. Ali , McCluskey Patrick , Joshi Shailesh 
Published: October 2017

Transient Liquid Phase Sintering (TLPS) is a novel high temperature attach technology. It is of particular interest for application as a die attach in power electronic systems because of its high melting temperature and high thermal conductivity. TLPS joints formed from sinter pastes are comprised of metallic particles embedded in matrices of Intermetallic Compounds (IMCs). Compared to conventional solder attach, TLPS joints contain a considerably higher percentage of brittle IMCs. This raises the concern that TLPS joints are susceptible to brittle failure. In this paper we describe and analyze the cooling-induced formation of vertical cracks as a newly detected failure mechanism unique to TLPS joints.
In a power module structure with a TLPS joint as interconnect between a power device and a Direct Bond Copper (DBC) substrate, cracks can form between the interface of the DBC and the TLPS joint when large voids are located in the proximity of the DBC. These cracks do not appear in regions with smaller voids. A method has been developed for the three-dimensional modeling of paste-based TLPS sinter joints that possess complex microstructures with heterogeneous distributions of metal particles and voids in IMC matrices. Thermo-mechanical simulations of the post-sintering cooling process have been performed and the influence of microstructure on the stress-response within the joint and at the joint interfaces have been characterized for three different material systems (Cu+Cu6Sn5, Cu+Cu3Sn, Ni+Ni3Sn4).
The maximum principal stress within the assembly was found to be a poor indicator for prediction of vertical crack formation. In contrast, stress levels at the interface between the TLPS joint and the power substrate metallization are good indicators for this failure mechanism. Small voids lead to higher joint maximum principal stresses, but large voids induce higher interfacial stresses, which explain why the vertical cracking failure was only observed in joints with large voids.
Preliminary Results on the Fabrication of Interconnect Structures Using Microscale Selective Laser Sintering
Authors: Roy Nilabh , Dibua Obehi , Foong Chee Seng , Cullinan Michael 
Published: October 2017

The ability to create 3D ICs can significantly increase transistor packing density, reduce chip area and power dissipation leading to possibilities of large-scale on-chip integration of different systems. A promising process for this application is the microscale additive manufacturing (AM) of 3D interconnect structures and capability of writing 3D metal structures with feature sizes of approximately 1 μm on a variety of substrates. Current microscale AM techniques are limited in their capabilities to produce 3D conductive interconnect structures. This paper presents the design and development of a new micro AM technique — microscale selective laser sintering (μ-SLS) — which overcomes many of the limitations of other micro AM processes to achieve true micron sized, electrically conductive features on a variety of substrates.
This paper will present preliminary results from set of sintering experiments on copper (Cu) nanoparticle (NP) ink using the continuous wave (CW) laser to be employed in the μ-SLS system which will be compared to Cu NP sintering results produced with other laser sources such as nanosecond (ns) & femtosecond (fs) lasers. This study is important to estimate the optimum working range of fluence/irradiance to be used in the μ-SLS setup depending upon the laser employed. In general, it provides an experimental estimate of the sintering fluence/irradiance range of Cu NPs depending upon the type of laser used and compares their sintering quality based on morphology of sintered spots.
Optimization of Graphite Composite Latent Heat Storage Systems
Authors: Mallow Anne , Gluesenkamp Kyle , Abdelaziz Omar , Graham Samuel 
Published: October 2017

The energy density and power density are critical properties of thermal energy storage systems. Use of a phase change material as the storage medium provides high energy density due to the ability to store energy as latent heat during the phase transition; however, the power density is limited by the low thermal conductivity. Insertion of a highly conductive graphite foam within the material can increase the rate of thermal response of the phase change material. As the graphite bulk density increases, the thermal conductivity increases, but the composite latent heat decreases due to displacement of the phase change material. This introduces a trade-off between energy density and power density of the composite.
In this work, a validated numerical model is used to study the trade-off between energy density and power density with respect to graphite bulk density under various imposed heat fluxes. Comparisons are made based on the melting time, junction temperature between the composite and the heat source, and the volumetric energy density. To simplify the complicated relationship between composite thermophysical properties and charging response, two non-dimensional numbers are used. The Fourier number provides a comparison between the heat storage and heat diffusion by considering the thermal conductivity, latent heat, sensible heat, density, melting time, and volume. A dimensionless temperature compares the junction temperature (temperature between the heat source and the composite) when the sample is fully melted to the melt onset temperature. These non-dimensional numbers can assist in the design of latent heat storage systems where some parameters are fixed (such as heat flux, junction temperature, mass, operating time, or required energy storage) and others must be determined by the design (such as required thermal conductivity or height).
Enterococcus faecalis Responds to Individual Exogenous Fatty Acids Independently of Their Degree of Saturation or Chain Length
Authors: Saito Holly E. , Harp John R. , Fozo Elizabeth M. 
Published: October 2017

ABSTRACT

Enterococcus faecalis
is a commensal of the human gastrointestinal tract that can persist in the external environment and is a leading cause of hospital-acquired infections. Given its diverse habitats, the organism has developed numerous strategies to survive a multitude of environmental conditions. Previous studies have demonstrated that
E. faecalis
will incorporate fatty acids from bile and serum into its membrane, resulting in an induced tolerance to membrane-damaging agents. To discern whether all fatty acids induce membrane stress protection, we examined how
E. faecalis
responded to individually supplied fatty acids.
E. faecalis
readily incorporated fatty acids 14 to 18 carbons in length into its membrane but poorly incorporated fatty acids shorter or longer than this length. Supplementation with saturated fatty acids tended to increase generation time and lead to altered cellular morphology in most cases. Further, exogenously supplied saturated fatty acids did not induce tolerance to the membrane-damaging antibiotic daptomycin. Supplementation with unsaturated fatty acids produced variable growth effects, with some impacting generation time and morphology. Exogenously supplied unsaturated fatty acids that are normally produced by
E. faecalis
and those that are found in bile or serum could restore growth in the presence of a fatty acid biosynthetic inhibitor. However, only the eukaryote-derived fatty acids oleic acid and linoleic acid provided protection from daptomycin. Thus, exogenous fatty acids do not lead to a common physiological effect on
E. faecalis
. The organism responds uniquely to each, and only host-derived fatty acids induce membrane protection.

IMPORTANCE
Enterococcus faecalis
is a commonly acquired hospital infectious agent with resistance to many antibiotics, including those that target its cellular membrane. We previously demonstrated that
E. faecalis
will incorporate fatty acids found in human fluids, like serum, into its cellular membrane, thereby altering its membrane composition. In turn, the organism is better able to survive membrane-damaging agents, including the antibiotic daptomycin. We examined fatty acids commonly found in serum and those normally produced by
E. faecalis
to determine which fatty acids can induce protection from membrane damage. Supplementation with individual fatty acids produced a myriad of different effects on cellular growth, morphology, and stress response. However, only host-derived unsaturated fatty acids provided stress protection. Future studies are aimed at understanding how these specific fatty acids induce protection from membrane damage.
Influence of
cis
Element Arrangement on Promoter Strength in Trichoderma reesei
Authors: Kiesenhofer Daniel P. , Mach Robert L. , Mach-Aigner Astrid R. 
Published: October 2017

ABSTRACT

Trichoderma reesei
can produce up to 100 g/liter of extracellular proteins. The major and industrially relevant products are cellobiohydrolase I (CBHI) and the hemicellulase XYNI. The genes encoding both enzymes are transcriptionally activated by the regulatory protein Xyr1. The first 850 nucleotides of the
cbh1
promoter contain 14 Xyr1-binding sites (XBS), and 8 XBS are present in the
xyn1
promoter. Some of these XBS are arranged in tandem and others as inverted repeats. One such
cis
element, an inverted repeat, plays a crucial role in the inducibility of the
xyn1
promoter. We investigated the impact of the properties of such
cis
elements by shuffling them by insertion, exchange, deletion, and rearrangement of
cis
elements in both the
cbh1
and
xyn1
promoter. A promoter-reporter assay using the
Aspergillus niger
goxA
gene allowed us to measure changes in the promoter strength and inducibility. Most strikingly, we found that an inverted repeat of XBS causes an important increase in
cbh1
promoter strength and allows induction by xylan or wheat straw. Furthermore, evidence is provided that the distances of
cis
elements to the transcription start site have important influence on promoter activity. Our results suggest that the arrangement and distances of
cis
elements have large impacts on the strength of the
cbh1
promoter, whereas the sheer number of XBS has only secondary importance. Ultimately, the biotechnologically important
cbh1
promoter can be improved by
cis
element rearrangement.

IMPORTANCE
In the present study, we demonstrate that the arrangement of
cis
elements has a major impact on promoter strength and inducibility. We discovered an influence on promoter activity by the distances of
cis
elements to the transcription start site. Furthermore, we found that the configuration of
cis
elements has a greater effect on promoter strength than does the sheer number of transactivator binding sites present in the promoter. Altogether, the arrangement of
cis
elements is an important factor that should not be overlooked when enhancement of gene expression is desired.
Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli Cells Artificially Internalized into Vegetable Seeds during Germination
Authors: Liu Da , Cui Yue , Walcott Ronald , Chen Jinru 
Published: October 2017

ABSTRACT

Vegetable seeds contaminated with bacterial pathogens have been linked to fresh-produce-associated outbreaks of gastrointestinal infections. This study was undertaken to observe the physiological behavior of
Salmonella enterica
and enterohemorrhagic
Escherichia coli
(EHEC) cells artificially internalized into vegetable seeds during the germination process. Surface-decontaminated seeds of alfalfa, fenugreek, lettuce, and tomato were vacuum-infiltrated with four individual strains of
Salmonella
or EHEC. Contaminated seeds were germinated at 25°C for 9 days, and different sprout/seedling tissues were microbiologically analyzed every other day. The internalization of
Salmonella
and EHEC cells into vegetable seeds was confirmed by the absence of pathogens in seed-rinsing water and the presence of pathogens in seed homogenates after postinternalization seed surface decontamination. Results show that 317 (62%) and 343 (67%) of the 512 collected sprout/seedling tissue samples were positive for
Salmonella
and EHEC, respectively. The average
Salmonella
populations were significantly larger (
P
< 0.05) than the EHEC populations. Significantly larger
Salmonella
populations were recovered from the cotyledon and seed coat tissues, followed by the root tissues, but the mean EHEC populations from all sampled tissue sections were statistically similar, except in pregerminated seeds. Three
Salmonella
and two EHEC strains had significantly larger cell populations on sprout/seedling tissues than other strains used in the study.
Salmonella
and EHEC populations from fenugreek and alfalfa tissues were significantly larger than those from tomato and lettuce tissues. The study showed the fate of internalized human pathogens on germinating vegetable seeds and sprout/seedling tissues and emphasized the importance of using pathogen-free seeds for sprout production.

IMPORTANCE
The internalization of microorganisms into vegetable seeds could occur naturally and represents a possible pathway of vegetable seed contamination by human pathogens. The present study investigated the ability of two important bacterial pathogens,
Salmonella
and enterohemorrhagic
Escherichia coli
(EHEC), when artificially internalized into vegetable seeds, to grow and disseminate along vegetable sprouts/seedlings during germination. The data from the study revealed that the pathogen cells artificially internalized into vegetable seeds caused the contamination of different tissues of sprouts/seedlings and that pathogen growth on germinating seeds is bacterial species and vegetable seed-type dependent. These results further stress the necessity of using pathogen-free vegetable seeds for edible sprout production.
Draft Genome Sequence of the Wood-Degrading Ascomycete
Kretzschmaria deusta
DSM 104547
Authors: Büttner Enrico , Gebauer Anna Maria , Hofrichter Martin , Liers Christiane , Kellner Harald 
Published: October 2017

ABSTRACT

We report here the draft genome of
Kretzschmaria
(
Ustulina
)
deusta
, an ascomycetous fungus that colonizes and substantially degrades hardwood and can infest living broad-leaved trees. The genome was assembled into 858 contigs, with a total size of 46.5 Mb, and 11,074 protein-coding genes were predicted.
Draft Genome Assembly of a
Wolbachia
Endosymbiont of
Plutella australiana
Authors: Ward Christopher M. , Baxter Simon W. 
Published: October 2017

ABSTRACT

Wolbachia
spp. are endosymbiotic bacteria that infect around 50% of arthropods and cause a broad range of effects, including manipulating host reproduction. Here, we present the annotated draft genome assembly of
Wolbachia
strain wAus, which infects
Plutella australiana
, a cryptic ally of the major
Brassica
pest
Plutella xylostella
(diamondback moth).
Complete Genome Sequence of the Circulatory Foot-and-Mouth Disease Virus Serotype Asia1 in Bangladesh
Authors: Ali M. Rahmat , Alam A. S. M. Rubayet Ul , Amin M. Al , Ullah Huzzat , Siddique Mohammad Anwar , Momtaz Samina , Sultana Munawar , Hossain M. Anwar 
Published: October 2017

ABSTRACT
The complete genome sequence of foot-and-mouth disease virus (FMDV) serotype Asia1 isolated from Bangladesh is reported here. Genome analysis revealed amino acid substitutions in the VP1 antigenic region and deletions in both the 5′ and 3′ untranslated regions (UTRs) compared to the genome of the existing vaccine strain (GenBank accession no. AY304994).
Complete Coding Genome Sequences of Uncommon GII.8 Sapovirus Strains Identified in Diarrhea Samples Collected from Peruvian Children
Authors: Kagning Tsinda Emmanuel , Malasao Rungnapa , Furuse Yuki , Gilman Robert H. , Liu Xiaofang , Apaza Sonia , Espetia Susan , Cama Vitaliano , Oshitani Hitoshi , Saito Mayuko 
Published: October 2017

ABSTRACT
We report here two complete coding genome sequences of novel genotype GII.8 sapovirus strains identified in diarrhea samples collected from two Peruvian children. The complete coding genome sequences of both GII.8 variants were determined using the Sanger sequencing method.
Complete Genome Sequences of Cluster A Mycobacteriophages BobSwaget, Fred313, KADY, Lokk, MyraDee, Stagni, and StepMih
Authors: Butela Kristen A. , Gurney Susan M. R. , Hendrickson Heather L. , LeBlanc-Straceski Janine M. , Zimmerman Anastasia M. , Conant Stephanie B. , Freed Nikki E. , Silander Olin K. , Thomson Joshua J. , Berkes Charlotte A. , Bertolez Cristina , Davies Courtney G. , Elinsky Amber , Hanlon Alison J. , Nersesyan Juliette , Patel Payal , Sherwood John , Tieu Ngo Tiffany , Wisniewski Kathryn A. , Yacoo Kathrine , Arendse Paul M. , Bowlen Nathan W. , Cunmulaj Jasmina , Downs Julie L. , Ferrenberg Charlee A. , Gassman Alexandra E. , Gilligan Cody E. R. , Gorkiewicz Emily , Harness Christopher , Huffman Anthony , Jones Christina , Julien Anna , Kupic Alexis E. , Latu Sayonara F. , Manning Thomas J. , Maxwell Danielle ,   Merrimack College SEA-PHAGES Annotators 2016, Meyer Catherine E. , Reardon Madeleine , Slaughter Matthew , Swasey Royce , Tennent Rebecca I. , Torres Victoria , Waller Tamia , Worcester Rachel M. , Yost Brooke L. , Cresawn Steven G. , Garlena Rebecca A. , Jacobs-Sera Deborah , Pope Welkin H. , Russell Daniel A. , Hatfull Graham F. , Kagey Jacob D. 
Published: October 2017

ABSTRACT

Seven mycobacteriophages from distinct geographical locations were isolated, using
Mycobacterium smegmatis
mc
2
155 as the host, and then purified and sequenced. All of the genomes are related to cluster A mycobacteriophages, BobSwaget and Lokk in subcluster A2; Fred313, KADY, Stagni, and StepMih in subcluster A3; and MyraDee in subcluster A18, the first phage to be assigned to that subcluster.
Does the association between leisure activities and survival in old age differ by living arrangement?
Authors: Nilsen Charlotta , Agahi Neda , Shaw Benjamin A 
Published: October 2017

BackgroundGovernment policies to promote ageing in place have led to a growing frail population living at home in advanced old age, many of whom live alone. Living alone in old age is associated with adverse health outcomes, but we know little about whether it moderates the health impact of other risk and protective factors. Engagement in leisure activities is considered critical to successful ageing. We investigated whether the association between different types of leisure activities and survival in non-institutionalised older adults (aged 76 and above) differs by living arrangement and gender.MethodsWe used the Swedish Panel Study of Living Conditions of the Oldest Old study from 2011 and the Swedish Cause of Death Register (until 30 June 2014) to conduct Cox regression analyses (n=669). Incident mortality was 30.2% during the follow-up period.ResultsOverall level of leisure activity was not significantly associated with survival in either living arrangement, but some specific leisure activities, and associations, were different across gender and living arrangement. More specifically, certain social activities (participation in organisations and having relatives visit) were associated with longer survival, but only in men living alone. In women, most results were statistically non-significant, with the exception of solving crosswords being associated with longer survival in women living with someone.ConclusionIn order to facilitate engagement with life, interventions focusing on leisure activities in the oldest age groups should take gender and living arrangement into consideration when determining the type of activity most needed.