bluuebunny/crossref_metadata_2025 huggingface dataset:
Hygienic conditions influence sensitization to Blomia tropicalis allergenic components: Results from the FRAAT birth cohort
Authors: Zakzuk Josefina , Mercado Dilia , Bornacelly Adriana , Sánchez Jorge , Ahumada Velky , Acevedo Nathalie , Caraballo Luis
Published: November 2018

Background

In tropical zones, perennial exposure to house dust mite (HDM) allergens and helminth infections is present. Studying the impact of these conditions on the inception and evolution of allergic diseases is necessary to have an accurate view of their natural history. We aimed to evaluate the dynamics of genuine sensitization to Blomia tropicalis and Ascaris in children from the FRAAT birth cohort and the effects of helminth infection, environmental HDM allergen levels, and sociodemographic factors.

Methods

Children were followed up to 6 years old. Specific IgE to recombinant allergens from B. tropicalis (Blo t 5 and Blo t 12) and Ascaris spp (Asc l 3, Asc l 13 and Asc s 1) was measured by ELISA at different time points. Allergen levels were measured in dust when children were 6 months old.

Results

IgE sensitization increased over time up to 3 years old. Correlation among the specific IgE levels to B. tropicalis and Ascaris components is poor at year 1, but coefficients are high and significant (Spearman's rho coefficients >0.70) at year 6. Unhygienic conditions increased the odds of sensitization to B. tropicalis allergenic components. Blo t 5 levels were lower in the poorest. IgE response to Blo t 5 and Blo t 12 was less intense in children with high exposure to Blo t 5 (levels >80th percentile).

Conclusion

In this tropical community, the pattern of childhood IgE sensitization is different from that in developing countries and is influenced by the hygienic conditions.
I am more than a mom: Stories of parental leave during the transition to motherhood in Canada
Authors: Paterson Stephanie , Hebblethwaite Shannon , Trussell Dawn , Evans Meredith , Xing Trisha
Published: November 2018

The transition to motherhood is a time of tremendous change, during which maternal subjects experience important shifts in their relationships with family, friends, employers, and state. Parental leave policies have potential to mitigate some of these changes, contributing positively to health and economic outcomes. Indeed, such policies have been identified as essential for achieving gender equality, serving to address both recognition and redistributive claims. In this paper, we explore parental leave policy through the lens of first time mothers in Canada, where two distinct policy regimes coexist. Using narrative analysis, we examine the ways in which the transition to motherhood is embodied and enacted through policy experiences. The stories we uncover, stories of helplessness, of control and resistance, and of stymied progress, illuminate how leave policies differently position maternal subjects in complex social settings.
“We do STEM”: Unsettled conceptions of STEM education in middle school S.T.E.M. classrooms
Authors: Kloser Matthew , Wilsey Matthew , Twohy Kyra E. , Immonen Audrey D. , Navotas Ariel C.
Published: November 2018

STEM education has received attention both as a reform pedagogy and as a public means for economic growth and national security. Yet, despite this attention, clarity about what “counts” as STEM and how the individual disciplines relate to an integrated approach remains ambiguous. This article elicits the conceptions about what constitutes STEM education from middle grade teachers across the United States who teach a STEM discipline. Based on coded interviews and drawn conceptual models, participating teachers were more likely to describe essential aspects of integrated STEM found in the literature, but when asked to draw their conception of STEM education in their context, they often represented less ambitious conceptions. Furthermore, nontraditional subjects like engineering and technology were sometimes represented in subordinate ways to traditional subjects like science and mathematics. These findings have implications for preparing teachers to engage students in integrated STEM learning experiences as well as policy implications for what requirements must be in place to fund new STEM learning opportunities.
Characterization of the novel HLA‐DRB5*02:21 allele by sequencing‐based typing
Authors: Cargou Marine , Ralazamahaleo Mamy , Blouin Laura , Guidicelli Gwendaline , Visentin Jonathan
Published: November 2018

HLA‐DRB5*02:21 differs from HLA‐DRB5*02:02:01 by one nucleotide substitution at codon 203 in exon 4.
Characterization of the novel HLA‐A*30:135 allele by sequencing‐based typing
Authors: Cargou Marine , Ralazamahaleo Mamy , Blouin Laura , Guidicelli Gwendaline , Visentin Jonathan
Published: November 2018

HLA‐A*30:135 differs from HLA‐A*30:01:01 by one nucleotide substitution at codon 304 in exon 5.
HLA‐B*45:22: a novel allele that differs from HLA‐B*45:01:01 at several locations
Authors: Dukek Brian A. , Zuccarelli Micah D. , Wakefield Laurie L. , Kreuter Justin D. , Gandhi Manish J.
Published: November 2018

Discovery of a novel HLA‐B*45:22 allele in a Middle Eastern heart and lung transplant candidate.
Red cell supernatant effects on endothelial cell function and innate immune activation is influenced by donor age and sex
Authors: Kipkeu Betty J. , Almizraq Ruqayyah , Branch Donald R. , Acker Jason P. , Holovati Jelena L.
Published: November 2018

Background and objectives

Blood donor characteristics significantly affect the pre‐storage and post‐storage quality of red cell concentrates (RCCs). This study investigated the impact of donor age and sex on RCC characteristics and the effect of RCC supernatants on the vascular endothelium and monocytes.

Materials and methods

RCC units selected from four donor groups based on donor age and sex (male ≤ 30‐years old (yo), male ≥ 60‐yo, female ≤ 30‐yo and female ≥ 60‐yo) were stored at 1–6°C and tested on day 7, 21 and 42. RCC supernatants were analysed for the number, concentration and size of extracellular vesicles (EVs). Human vein endothelial cells (HUVECs) monolayers were incubated with RCC supernatants and assessed for expression of vascular cell adhesion molecule‐1 (VCAM‐1) and E‐selectin by flow cytometry as well as endothelial permeability using a trans‐epithelial‐electrical‐resistance assay. Monocytes and HUVECs were incubated with RCC supernatants and supernatants assayed for cytokines/chemokines.

Results

RCCs from female donors were found to have lower unit volume, haemoglobin content and haematocrit compared to RCCs from male donors (P < 0·05). RCC supernatants from female ≥ 60‐yo had a higher concentration of large EVs (≥200 nm) compared to both male ≤ 30‐yo (P = 0·039) and male ≥ 60‐yo supernatants (P = 0·019). Treatment with RCC supernatants from male ≤ 30‐yo donors induced lower expression of VCAM‐1, lower cytokine/chemokine release and showed the least effect on endothelial permeability.

Conclusion

Donor characteristics affect RCC quality parameters and influence the endothelial and immune modulation potential of RCC supernatants in vitro.
Evaluation of the effects of seasonal changes in sediment characteristics on macroinvertebrate assemblage in a tropical reservoir
Authors: Babatunde Amusan , Gbenga Omoniyi , Sylvester Ogbogu
Published: November 2018

Osinmo Reservoir is an important water body in south‐western Nigeria. Despite being critically important, there is a lack of detailed biological studies on this reservoir. This study investigated the effect of seasonal variations on the characteristics of the sediment and the community structure of the macroinvertebrates in the reservoir between May 2012 and March 2014. The sediment was generally slightly acidic and was dominated by silty sand and sandy mud with low organic matter. Twenty‐four taxa of macroinvertebrates with a total abundance of 55,065 individuals (ind.) belonging to three phyla were recorded. Overall, the composition and the abundance of the macroinvertebrates were not significantly different (P > 0.05) in the wet and dry seasons. Seasonal variations in the sediment quality did not have a significant impact on the community metrics such as species diversity, species richness and species evenness. The dominance of sensitive species indicated a moderately clean status of the reservoir.
Improvement of laser induced breakdown spectroscopy signal for sodium chloride solution
Authors: Harun Hanin Athirah , Zainal Roslinda
Published: November 2018

Laser induced breakdown spectroscopy (LIBS) is one of the analytical spectroscopy technique used in determining elemental composition of solid, liquid or gas sample using high energy laser pulse. However, LIBS technique associated with liquid sample often suffers from strong splashing and shockwave, thereby affecting the LIBS experiment repeatability and performance analysis. Therefore, a simple and quick-freeze sample pre-treatment approach using Peltier Thermoelectric Cooler (TEC) to solidify the water is applied to maintain the inherent homogeneity and chemical composition of the initial liquid sample before each LIBS analysis. This approach successfully solidified and maintained the liquid sample at its freezing point throughout the LIBS signal acquisition process. In this work, the qualitative analysis liquid samples and its solidified form, consisting of 0.5, 1.0, 1.5 and 2.0 mol/L sodium chloride (NaCl) were determined under similar experimental conditions by using LIBS. Plasmas were produced by focusing the output of Nd: YAG laser (1064nm, 6 ns and 1 Hz) on the surface of the bulk NaCl solution and its solidified form. LIBS signatures for sodium (Na) and chlorine (Cl) atomic emission lines (589.00 and 499.55 nm, respectively) were collected for estimating sodium and chlorine depositions in NaCl solutions to indicate correlation between their assay and LIBS measurements. For solidified sample, Na and Cl showed improved signal-to-noise ratio and limits of detection (47.8% and 8.8%, respectively) without the difficulties usually associated with liquid samples, demonstrating the benefits of this sample pre-treatment approach.
Antibacterial activity of copper exchanged zeolite Y synthesized from rice husk ash
Authors: Nik Malek Nik Ahmad Nizam , Azid Nurul Ain , Abdul Hadi Atieya , Ishak Siti Nabihan , Asraf Muhammad Hariz , Amir Awaluddin Muhammad Zulhilmi
Published: November 2018

Increasing problems with antibacterial agent primarily bacterial resistance and environmental pollution due to the high release of antibacterial agents in water necessitates the development of new and effective antibacterial agents. One of the techniques that can be used to overcome these problems is by immobilizing antibacterial compounds or any related compounds on the carrier system such as by using zeolite. In this study, zeolite Y was synthesized from rice husk ash as silica source by using hydrothermal technique and it was used as a carrier system for antibacterial copper (Cu) ions. A series of Cu-exchanged zeolite Y was then prepared by loading with different concentrations of Cu ions (100 ppm, 600 ppm and 900 ppm of the Cu(NO3)2) on the synthesized zeolite Y. The Cu-exchanged zeolite Y was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). These characterization techniques showed that the zeolite Y was synthesized in pure phase and had a good degree of crystallinity. Whereas, from the characterization results, zeolite Y was successfully loaded with different concentrations of Cu ions and no structural changes happen after modification. The antibacterial activity of the samples was determined through disc diffusion technique (DDT) against Gram positive bacteria (Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 29212) and Gram negative bacteria (Escherichia coli ATCC 11229 and Pseudomonas aeruginosa ATCC 15442). Based on the antibacterial results, the synthesized zeolite Y loaded with 900 ppm of Cu2+ showed the highest antibacterial activity compared to that of loaded with 100 ppm and 600 ppm of Cu2+. The higher the Cu concentration on the zeolite Y resulted in the higher antibacterial activity against wide spectrum of bacteria. As a conclusion, synthesized zeolite Y from rice husk ash could be a carrier system for antibacterial Cu ions and it has the potential for the application as antibacterial agents.
Simultaneous action of surfactant modified clinoptilolite: Adsorbent of dyes and antibacterial agent
Authors: Abd Aziz Muhammad Syafiq , Nik Malek Nik Ahmad Nizam , Ishak Siti Nabihan , Asraf Muhammad Hariz , Abdul Hadi Atieya , Amir Awaluddin Muhammad Zulhilmi
Published: November 2018

In this study, the simultaneous action of surfactant modified clinoptilolite (SMC) as adsorbent for dyes and its antibacterial activity was investigated. Methylene blue (MB) and acid orange 7 (AO7) represent cationic and anionic dyes, respectively were used as adsorbate in this study and the antibacterial activity was studied against Gram-negative (Escherichia coli ATCC 11229) and Gram-positive bacteria (Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 2921). Initially, natural zeolite clinoptilolite was modified with 3 different concentrations (0.1, 1.0 and 4.0 mM) of cationic surfactant hexadecyltrimethyl ammonium bromide (HDTMA-Br). The SMC samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), amount of HDTMA adsorbed and dispersion behaviour. Result from XRD shows that the HDTMA-Br molecules caused no effect on primary structure of the clinoptilolite since the clinoptilolite structure remained the same after modification with HDTMA-Br. Compared to the unmodified clinoptilolite, FTIR spectra of the SMC shows peak corresponds to C-H stretches which proved the attachment of HDTMA onto the clinoptilolite surfaces. In the dispersion behaviour study, SMC samples were located at the adjacent phase between the water and oil mixture. The amount of HDTMA-Br adsorbed onto the clinoptilolite increased with the increasing concentrations of the surfactant. The use of SMC as adsorbent and antibacterial agent were further studied against the ionic dyes and bacteria simultaneously. The results show that the adsorption capacity of SMC towards both ionic dyes increase with the increasing HDTMA-Br concentration. While for the antibacterial activity, the number of colony forming unit of bacteria seem to be highly reduced at the highest concentration of the HDTMA (4.0 mM) attached on the clinoptilolite. Hence, this study had shown that SMC has high adsorption capacity towards the ionic dyes at the same time reducing the growth of both Gram positive and negative bacteria in aquoes solution.
Physicochemical properties of char derived from palm fatty acid distillate
Authors: Aderemi Hamzat Bashir , Nasri Noor Shawal , Ahmad Zaini Muhammad Abbas
Published: November 2018

The present work was aimed to evaluate the physiochemical properties of chars derived from palm fatty acid distillate. The palm fatty acid distillate was heat-treated at 500 °C and 600 °C in a muffle furnace for 0.5 h, and the resultant products were characterized for elemental composition, surface functional groups, thermogravimetric profile and methylene blue adsorption. Results show that the char samples are rich in carbon content with unique surface functional groups that could be useful in the liquid-phase adsorption. The solid chars depict a thermally stable profile with the increase of temperature during the heat treatment. The char demonstrated the maximum removal of methylene blue of 7.6 mg/g and obeyed the monolayer-trend adsorption of Langmuir isotherm. The findings concluded that the palm fatty acid distillate-based char could be an adsorbent candidate for the removal of methylene blue.
Palm tocotrienol-rich-fraction yields higher numbers of normal embryos whereas alpha-tocopherol produces higher preimplantation survival in murine embryos
Authors: Sarbandi Mimi Sophia , Eshak Zolkapli , Abd Rahman Nor Shahida , Abdul Aziz Abu Thalhah , Rajikin Mohd Hamim , Hashim Nooraain , Ahmad Zatul Akmar , Mohamed Noor Khan Nor Ashikin
Published: November 2018

Vitamin E contains isomers of tocotrienols and tocopherols. Studies have shown that palm tocotrienol-rich-fraction (TRF) improves preimplantation development of murine embryos. The aim of this study is to investigate the effects of TRF and α-tocopherol supplementation on preimplantation embryonic morphology, development and mitochondrial ultrastructure. Female C57Bl/6 mice were supplemented with 60 mg/kg body weight per day TRF and α-tocopherol for seven days. The females were superovulated and mated with fertile males to obtain 2-cell stage embryos. Initial assessment of normal and abnormal morphology was carried out on 2-cell embryos. The embryos were then cultured until the blastocyst stage. At the 8-cell stage, embryos were subjected to Transmission Electron Microscopy (TEM) to observe their mitochondria. Results showed that palm TRF produced significantly higher numbers of normal 2-cell embryos compared with α-tocopherol (80.9% vs 31.4%) at p< 0.01. Alpha-tocopherol produced higher survival rate to the blastocyst stage compared with palm TRF (42.2% vs 20.6%) at p< 0.01. The TRF group showed more vacuolated mitochondria at 8-cell stage compared to the α-tocopherol group, which may have contributed to a decline in preimplantation survival rates.
Three-Dimensional Finite Element Study on Lithium Diffusion and Intercalation-Induced Stress in Polycrystalline LiCoO2 Using Anisotropic Material Properties
Authors: Wu Linmin , Zhang Jing
Published: November 2018

In this study, lithium (Li) intercalation-induced stress of LiCoO2 with anisotropic properties using three-dimensional (3D) microstructures has been studied systematically. Phase field method was employed to generate LiCoO2 polycrystals with varying grain sizes. Li diffusion and stresses inside the polycrystalline microstructure with different grain size, grain orientation, and grain boundary diffusivity were investigated using finite element method. The results show that the anisotropic mechanical properties and Li concentration-dependent volume expansion coefficient have a very small influence on the Li chemical diffusion coefficients. The low partial molar volume of LiCoO2 leads to this phenomenon. The anisotropic mechanical properties have a large influence on the magnitude of stress generation. Since the Young's modulus of LiCoO2 along the diffusion pathway (a–b axis) is higher than that along c–axis, the Li concentration gradient is larger along the diffusion pathway. Thus, for the same intercalation-induced strain, the stress generation will be higher (∼40%) than that with isotropic mechanical properties as discussed in our previous study (Wu, L., Zhang, Y., Jung, Y.-G., and Zhang, J., 2015, “Three-Dimensional Phase Field Based Finite Element Study on Li Intercalation-Induced Stress in Polycrystalline LiCoO2,” J. Power Sources, 299, pp. 57–65). This work demonstrates the importance to include anisotropic property in the model.
Experimental Investigation of Nozzle Spacing Effects on Characteristics of Round Twin Free Jets
Authors: Laban Andrew , Aleyasin Seyed Sobhan , Tachie Mark Francis , Koupriyanov Mike
Published: November 2018

The objective of this paper is to investigate the effects of nozzle spacing on the mean velocity and higher-order turbulent statistics of free twin round jets produced from sharp contraction nozzles. The experiments were performed in an air chamber where four nozzle spacing ratios, S/d = 2.8, 4.1, 5.5, and 7.1, were investigated at a fixed Reynolds number of 10,000. A planar particle image velocimetry (PIV) system was used to conduct the velocity measurements. The results show that downstream of the potential core, a reduction in spacing ratio leads to an earlier and more intense interaction between the jets, indicated by enhanced half-velocity width spread rate in the inner shear layers and a significant rise of turbulent intensities and vorticity thickness along the symmetry plane. A reduction in spacing ratio, however, confines the ambient fluid entrainment along the inner shear layers leading to a reduced core jet velocity decay rate. The closer proximity of the jets also leads to the decrease of Reynolds stresses in the inner shear layers but not in the outer shear layers. The Reynolds stress ratios along the jet centerline reveal the highest anisotropy in the potential core region.
Numerical Modeling and Analysis of a Hybrid-Spar Floating Wind Turbine
Authors: Utsunomiya Tomoaki , Sato Iku , Kobayashi Osamu , Shiraishi Takashi , Harada Takashi
Published: November 2018

In this paper, numerical modeling and analysis of a hybrid-spar floating wind turbine is presented. The hybrid-spar consists of steel at the upper part and precast prestressed concrete at the lower part. Such a configuration is referred to as a hybrid-spar in this paper. The hybrid spar was successfully installed offshore of Kabashima island, Goto city, Nagasaki prefecture, Japan, on Oct. 18, 2013 (see Utsunomiya et al., 2015, “Design and Installation of a Hybrid-Spar Floating Wind Turbine Platform,” ASME Paper No. OMAE2015-41544 for details). In this paper, some details on numerical modeling of the hybrid-spar for design load analysis are presented. Then, the validation of the numerical analysis model is presented for a full-scale hybrid-spar model with 2-MW wind turbine. The comparison has been made for the natural periods and the response during rated power production test. Basically, both comparisons have shown good agreement between the measured values and the simulation, showing reliability of the developed code and the numerical model.
Modeling and Analysis of Piezoelectric Energy Harvesting With Dynamic Plucking Mechanism
Authors: Fu Xinlei , Liao Wei-Hsin
Published: November 2018

Nonharmonic excitations are widely distributed in the environment. They can work as energy sources of vibration energy harvesters for powering wireless electronics. To overcome the narrow bandwidth of linear vibration energy harvesters, plucking piezoelectric energy harvesters have been designed. Plucking piezoelectric energy harvesters can convert sporadic motions into plucking force to excite vibration energy harvesters and achieve broadband performances. Though different kinds of plucking piezoelectric energy harvesters have been designed, the plucking mechanism is not well understood. The simplified models of plucking piezoelectric energy harvesting neglect the dynamic interaction between the plectrum and the piezoelectric beam. This research work is aimed at investigating the plucking mechanism and developing a comprehensive model of plucking piezoelectric energy harvesting. In this paper, the dynamic plucking mechanism is investigated and the Hertzian contact theory is applied. The developed model of plucking piezoelectric energy harvesting accounts for the dynamic interaction between the plectrum and the piezoelectric beam by considering contact theory. Experimental results show that the developed model well predicts the responses of plucking piezoelectric energy harvesters under different plucking velocities and overlap lengths. Parametric studies are conducted on the dimensionless model after choosing appropriate scaling. The influences of plucking velocity and overlap length on energy harvesting performance and energy conversion efficiency are discussed. The comprehensive model helps investigate the characteristics and guide the design of plucking piezoelectric energy harvesters.
Experimental Investigation of the Effect of Nanofluid on Thermal Energy Storage System Using Clathrate
Authors: Hassan M. A. M. , Abdel-Hameed H. M. , Mahmoud Osama E.
Published: November 2018

Climatic change illustrates the need to new policy of load management. In this research, a special design of thermal energy storage (TES) system, with an appropriate storage medium that is suitable for residential and commercial buildings has been constructed and commissioned. Direct contact heat transfer is a significant factor to enhance the performance of TES. Numerous experimental runs were conducted to investigate the clathrate formation and the characteristics of the proposed TES cooling system; in addition, the effect of using nanofluid particles Al2O3 on the formation of clathrate under different operating parameters was evaluated. The experiments were conducted with a fixed amount of water 15 kg, mass of refrigerant to form clathrate of 6.5 kg, nanofluid particles concentration ranged from 0.5% to 2% and the mass flux of refrigerant varied from 150 to 300 kg/m2 s. The results indicate that there is a significant effect of using nanoparticles concentration on the charging time of the clathrate formation. The percentage of reduction in charging time of about 22% was achieved for high nanoparticles concentration. In addition, an enhancement in charging time by increasing the refrigerant flow rate reaches 38% when the mass flux varied from 200 to 400 kg/m2 s. New correlation describing the behavior of the temperatures with the charging time at different nanoparticles concentrations is presented.
Design and Calibration of Resistive Stress Sensors on 4H Silicon Carbide
Authors: Jaeger Richard C. , Chen Jun , Suhling Jeffrey C. , Fursin Leonid
Published: November 2018

Stress sensors have shown potential to provide “health monitoring” of a wide range of issues related to packaging of integrated circuits, and silicon carbide offers the advantage of much higher temperature sensor operation with application in packaged high-voltage, high-power SiC devices as well as both automotive and aerospace systems, geothermal plants, and deep well drilling, to name a few.

This paper discusses the theory and uniaxial calibration of resistive stress sensors on 4H silicon carbide (4H-SiC) and provides new theoretical descriptions for four-element resistor rosettes and van der Pauw (VDP) stress sensors. The results delineate the similarities and differences relative to those on (100) silicon: resistors on the silicon face of 4H-SiC respond to only four of the six components of the stress state; a four-element rosette design exists for measuring the in-plane stress components; two stress quantities can be measured in a temperature compensated manner. In contrast to silicon, only one combined coefficient is required for temperature compensated stress measurements. Calibration results from a single VDP device can be used to calculate the basic lateral and transverse piezoresistance coefficients for 4H-SiC material.

Experimental results are presented for lateral and transverse piezoresistive coefficients for van der Pauw structures and p- and n-type resistors. The VDP devices exhibit the expected 3.16 times higher stress sensitivity than standard resistor rosettes.
All-Inorganic Multi-Color Converter Based on Eu3+-Doped Phosphor-in-Glass for White Light-Emitting Diodes
Authors: Peng Yang , Mou Yun , Xu Xujia , Cheng Hao , Li Hong , Chen Mingxiang , Luo Xiaobing
Published: November 2018

We proposed an all-inorganic multi-color converter based on Eu3+-doped phosphor-in-glass (PiG) for high-power white light-emitting diodes (WLEDs). The Eu3+-doped PiG was fabricated by screen-printing and low-temperature sintering a green phosphor into a Eu3+-doped glass matrix, which was prepared by a lead-free and low-melting glass frit doped with Eu3+ ions. When the Eu3+ doping content increases from 0.5 to 5 mol%, the transmittance of Eu3+-doped glass matrix is reduced while the red emission intensity is increased. In addition, with the green phosphor mass ratio of 30%, the Eu3+-doped PiG based WLEDs achieve a warm white light with a correlated color temperature (CCT) of 4496 K and a color rendering index (CRI) of 82 at the driving current of 350 mA. These results indicate that the Eu3+-doped PiG is a promising multi-color converter for high-power WLEDs.
Quantification of Underfill Influence to Chip Packaging Interactions of WLCSP
Authors: Wang Huayan , Shao Shuai , Pham Vanlai , Shang Panju , Zhong Cheng , Park Seungbae
Published: November 2018

Wafer Level Chip Scale Package (WLCSP) has been a favorable packaging solution for compact portable consumer electronics. The microelectronics industry introduced Extra Low K (ELK) to enhance electric performances with the cost of diminishing mechanical reliability. The ELK itself and its interfaces are highly fragile and susceptible to fracture. ELK cracking under bumps and ELK inter layer delamination (ILD) from die corners are often observed during and after solder reflow and qualification process such as accelerated thermal cycling (ATC). In this study, the underfill selection and its fillet formation influence to the Chip Packaging Interactions (CPI) of WLCSP was investigated through an experimental technique and numerical analysis. For the experimental assessment, thermo-mechanical interactions between die corner and underfill was investigated. Digital image correlation (DIC) technique with optical microscope was utilized to quantify the deformation behavior and strains of cross-sectioned WLCSP die corner subjected to thermal loading from 25°C to 125°C. The results clearly show captured deformations of die corner area under thermal loading. For the fillet formation influence, it shows that the high underfill fillet configuration gives higher normal strain at the die corner area during thermal cycling. For the underfill selection, it clearly shows that the strain difference at corner solder during thermal cycling caused by two different type of underfill material. Finally, finite element analysis (FEA) was conducted by simulating the thermal loading applied in the experiments and validated with experimental results. Then, using the FEA analysis, parametric study for underfill material properties and fillet height were performed on the ELK reliability of WLCSP. Energy release rate of the die corner crack were obtained and used as damage indicators for die corner ELK delamination.
Drive Schedule Impacts to Thermal Design Requirements and the Associated Reliability Implications in Electric Vehicle Traction Drive Inverters
Authors: Nafis Bakhtiyar Mohammad , Iradukunda Ange , Huitink David
Published: November 2018

Power output to electric traction drive systems varies over a wide range during real-world operation. As a result, the inverters, responsible for converting direct current battery (DC) to alternating current (AC) for electric motor operation, experience temperature changes that are important to consider in thermal design of the whole system, as well as implications for reliability in actual use. Because of the implications of temperature on device & system reliability, it is necessary to design appropriate thermal management systems to control their temperatures to meet product reliability goals. This study utilizes US Environmental Protection Agency standard driving schedules as case studies in how driving characteristics result in power module temperature profiles during operation for various heat removal schemes and design efficiencies. The temperature profiles obtained in this study clearly demonstrate a strong relationship between motor power output and inverter heat sink temperature. Moreover, when integrated with various degrees of road incline, the driving schedules show how road and elevation also impacts the need for various cooling technologies. This information can be integrated into use condition analyses for predicting reliability of the electronic components using reliability models developed from accelerated testing and qualifications to ensure the proper certification envelope is demonstrated for any given vehicle and environment, as well as demonstrate the effectiveness of cooling methods for determination of technical and economic feasibility.
Lidded vs. Lidless: A Thermal Study
Authors: Huang Xiaopeng , Gektin Vadim
Published: November 2018

In the recent years, lidless (bare) die packaging starts to appear in the high power applications with a large die size, complementing the conventional lidded packaging. Given the vast parameters’ space of the lidded vs. lidless designs, a systematic study is necessary to develop a clear and practical design recommendations. In this work, an analytical study is conducted to assess the sensitivity of the thermal spreading resistance (TSR) and the total junction-to-ambient thermal resistance (Rja) on various parameters for a typical lidded (LD) and lidless (LL) package configuration. Useful findings and design guidance are provided.
Viscoplastic Constitutive Model for High Strain Rate Mechanical Properties of SAC-Q Leadfree Solder After High-Temperature Prolonged Storage
Authors: Lall Pradeep , Yadav Vikas , Suhling Jeff , Locker David
Published: November 2018

Electronics in automotive underhood and downhole drilling applications may be subjected to sustained operation at high temperature in addition to high strain-rate loads. SAC solders used for second level interconnects have been shown to experience degradation in high strain-rate mechanical properties under sustained exposure to high temperatures. Industry search for solutions for resisting the high-temperature degradation of SAC solders has focused on the addition of dopants to the alloy. In this study, a doped SAC solder called SAC-Q solder have been studied. The high strain rate mechanical properties of SAC-Q solder have been studied under elevated temperatures up to 200°C. Samples with thermal aging at 50°C for up to 6-months have been used for measurements in uniaxial tensile tests. Measurements for SAC-Q have been compared to SAC105 and SAC305 for identical test conditions and sample geometry. Data from the SAC-Q measurements has been fit to the Anand Viscoplasticity model. In order to assess the predictive power of the model, the computed Anand parameters have been used to simulate the uniaxial tensile test and the model predictions compared with experimental data. Model predictions show good correlation with experimental measurements. The presented approach extends the Anand Model to include thermal aging effects.
Thermal Model Based Fault Detection and Isolation of Power Inverter IGBT Module
Authors: Zholbaryssov Madi , Sarwar Azeem
Published: November 2018

Penetration of electrified vehicles has increased steadily over the last decade due to unstable fuel prices, and the ability of such vehicle to offer lower cost per mile for transportation. At the same time, strict fuel emission standards continue to motivate the auto industry to invest resources on developing new technologies, which allow economically feasible electrification of vehicles and enable mass production. In electric vehicles, the electric drive system converts electrical energy into mechanical energy that powers the vehicle wheels. In this article, we present thermal model based fault detection and isolation methodology for power inverter insulated gate bipolar transistor (IGBT) modules, which play a key role in converting DC power from the battery into AC power that goes into the electric motor and drives the wheels through the transmission module. We do not propose any additional sensing capability, and make use of what is typically available in most of the production vehicles today across the industry. Results are presented from simulation studies that highlight the effectiveness of our proposed method.
Improved Approaches for FEA Analyses of PBGA Packages Subjected to Thermal Cycling
Authors: Chen Chienchih , Suhling Jeffrey C. , Lall Pradeep
Published: November 2018

The study of solder joint reliability is one of the priority issues in electronic packaging. Solder alloys experience a highly nonlinear material behavior when subject to thermal cycling. It is a time consuming and difficult task to study the behavior of solder joints using experimental approaches. Finite element analysis provides a more efficient way to better understand the behavior of solder joints when accurate material models are available. With the developments of FEA algorithms and computer resources, the analysis approaches used for electronic packaging assemblies have evolved from 2-dimensional to 3-dimensional analyses, with far fewer assumptions needed in the fully 3D case. In this paper, we compare different FEA approaches covering various 2D and 3D modeling techniques to understand their advantages and drawbacks, especially as related to simulation accuracy and efficiency. Several models for a typical BGA assembly were prepared and analyzed including traditional mesh continuity models (2D slice model, 3D slice model, and 3D quarter model), as well as advanced models that employ Multi-Point Constraints (MPCs) and submodeling (global/local models). The Anand viscoplastic model was used for the solder joint material behavior in all of the FEA approaches.

For the 3D mesh continuity models, an optimal analysis approach has been proposed to achieve the best balance between the accuracy of the simulation result and numerical efficiency of the simulation. Mesh transitions were used to maintain mesh continuity between regions of different mesh densities. A best choice of load step size was also found to reduce overall simulation time. For the analysis using MPCs to to bond different meshes, two improved modeling strategies have been proposed including a suggested ratio of contacting elements and the use of multiple-MPC contact pairs to reduce overall mesh density of the FE model. An improved simulation simulation strategy using submodeling has also been developed to obtain the best compromise in the global and local models between the mesh quality and load step size. An improved geometric simplification of the solder joint for use with energy based fatigue criteria was developed. Finally, comparisons and suggestions were made for the best analysis approach when using FEA techniques to predict the behavior of solder joints in PBGA packages.
Measurement of the Thermal Performance of a Single-Phase Immersion Cooled Server at Elevated Temperatures for Prolonged Time
Authors: Bansode Pratik V. , Shah Jimil M. , Gupta Gautam , Agonafer Dereje , Patel Harsh , Roe David , Tufty Rick
Published: November 2018

Fully immersion of servers in electrically nonconductive (dielectric) fluid has recently become a promising technique for minimizing cooling energy consumption in data centers. The improved thermal properties of these dielectric fluids facilitate considerable savings in both upfront and operating cost over traditional air-cooling. This technology provides an opportunity for accommodating increased power densities. It also minimizes the common operational issues of air cooling technique like overheating and temperature swing in the system, fan failures, dust, air quality, and corrosion. This paper presents various data about the thermal performance of a fully single-phase dielectric fluid immersed server over wide temperature ranges (environment temperatures) from 25°C to 55°C for prolonged periods in an environmental chamber. This work explores the effects of high temperatures on the performance of a server and other components like pump, along with potential issues associated with extreme climatic conditions. The experimental data serves as a means to determine failure criteria for the server and pump by subjecting the system to accelerated thermal aging conditions i.e. around 55°C, consequently simulating the most extreme environmental condition that the server may encounter. Connector seals are inspected for expected degradation upon temperature cycling typically at such extreme conditions. Throttling limit for the server and pump power draw for different temperatures was determined to assess pump performance. Determining the relations between component behavior and operating temperature provides an accurate measure of lifetime of a server. The scope of this paper can be expanded by reviewing the effects of low temperatures on server and component performance. Changes to various performance parameters like power draw of pump and server at the higher and the lower operating temperatures and an understanding of issues like condensation can be used to quantify upper and lower limits for pump and server performance.
Evaporative Wicking Phenomena on Nanotextured Surfaces for Heat Pipe Applications
Authors: Le Duong Vy , Zhang Shiwei , Lee Jonggyu , Won Yoonjin
Published: November 2018

Thermal management has become more important as high-performance electronics have concentrated heat loads with current cooling technologies. This motivates the implementation of new cooling solutions to dissipate high heat levels from high-performance electronics. Evaporative cooling is one of the most promising approaches for meeting these future thermal demands. Thin-film evaporation promotes heat dissipation through the phase change process with minimal conduction resistance. In this process, it is important to design surface properties and structures that can minimize meniscus thickness, increase liquid-vapor interface area, and enhance evaporation performances. In this study, we thereby investigate thin-film evaporation by employing nanotextured copper substrates for varying thermal conditions. Specifically, we visualize the liquid spreading on the nanotextured surfaces using a high-speed imaging technique to quantify evaporative heat transfer for various designs. The permeability is calculated using an enhanced wicking model to account for the evaporation effect. The mass balance measurements allow us to calculate evaporation rates. Then, we employ infrared thermography to examine two-dimensional temporal temperature profiles of the samples during the evaporative wicking with a given heat flux. The combination of time-lapse images, evaporation rate measurements, and temperature profiles will provide a comprehensive understanding of evaporation performances of textured surfaces.
Single electron transistors with e-beam evaporation of SiO2 tunnel barriers
Authors: Filmer Matthew J. , Snider Gregory L. , Orlov Alexei O.
Published: November 2018

Recent work on fabricating metal-insulator-metal (MIM) single electron transistors (SETs) using deposited dielectrics shows promise for becoming a manufacturable process due to compatibility with modern CMOS processes. This process, the “rib-SET” process [V. Joshi, A. O. Orlov, and G. L. Snider, J. Vac. Sci. Technol. B 26, 2587 (2008); G. Karbasian, A. O. Orlov, and G. L. Snider, J. Vac. Sci. Technol. B 33 (2015)], features a self-aligned island and should allow for scaling SETs below 10 nm. However, one of the biggest roadblocks in realizing a high-quality SET with this process has been difficulties in developing high-quality, low-noise, MIM tunnel junctions. In this work, the authors report Pt-SiO2-Pt MIM SETs with tunnel barriers deposited by e-beam evaporation as an alternative to atomic layer deposition. There are some challenges in the formation of tunnel barriers via e-beam evaporation that are addressed. It is expected that platinum has a negligible native oxide; however, there is a substantial resistance in as-deposited Pt-SiO2-Pt structures that can be reduced by over 5 orders of magnitude by subjecting the finished devices to an anneal in a hydrogen plasma, suggesting the presence of an interfacial platinum oxide. It is shown that this treatment not only increases the conductance through the SET, but that it is necessary for forming high conductance tunnel barriers that are desired for making low-noise SETs.
Hypoxia-induced interaction of filamin with Drp1 causes mitochondrial hyperfission–associated myocardial senescence
Authors: Nishimura Akiyuki , Shimauchi Tsukasa , Tanaka Tomohiro , Shimoda Kakeru , Toyama Takashi , Kitajima Naoyuki , Ishikawa Tatsuya , Shindo Naoya , Numaga-Tomita Takuro , Yasuda Satoshi , Sato Yoji , Kuwahara Koichiro , Kumagai Yoshito , Akaike Takaaki , Ide Tomomi , Ojida Akio , Mori Yasuo , Nishida Motohiro
Published: November 2018

Filamin enhances Drp1-mediated mitochondrial fission and cellular senescence after myocardial infarction.
Monitoring of Fluconazole and Caspofungin Activity against
In Vivo
Candida glabrata Biofilms by Bioluminescence Imaging
Authors: Persyn Aranka , Rogiers Ona , Brock Matthias , Vande Velde Greetje , Lamkanfi Mohamed , Jacobsen Ilse D. , Himmelreich Uwe , Lagrou Katrien , Van Dijck Patrick , Kucharíková Soňa
Published: November 2018

Candida glabrata
can attach to various medical implants and forms thick biofilms despite its inability to switch from yeast to hyphae. The current
in vivo
C. glabrata
biofilm models only provide limited information about colonization and infection and usually require animal sacrifice.
Escherichia coli
Lrp Regulates One-Third of the Genome via Direct, Cooperative, and Indirect Routes
Authors: Kroner Grace M. , Wolfe Michael B. , Freddolino Lydia
Published: November 2018

To survive, bacteria such as
E. coli
must rapidly respond to changing environmental conditions, including nutrient levels. A decrease in nutrient availability causes bacteria to stop rapid replication and enter stationary phase, where they perform limited to no cell division. The
E. coli
global regulatory protein Lrp has been previously implicated in modulating the expression of genes particularly important at this transition from rapid to slowed growth. Here, we monitor Lrp’s DNA binding locations and effect on gene expression under three different nutrient conditions across three growth stages. We find that Lrp’s role is even broader than previously suspected and that it appears to interact with many other bacterial regulators to perform its function in a condition-specific manner.
Replication-Competent NYVAC-KC Yields Improved Immunogenicity to HIV-1 Antigens in Rhesus Macaques Compared to Nonreplicating NYVAC
Authors: Kibler Karen V. , Asbach Benedikt , Perdiguero Beatriz , García-Arriaza Juan , Yates Nicole L. , Parks Robert , Stanfield-Oakley Sherry , Ferrari Guido , Montefiori David C. , Tomaras Georgia D. , Roederer Mario , Foulds Kathryn E. , Forthal Donald N. , Seaman Michael S. , Self Steve , Gottardo Raphael , Phogat Sanjay , Tartaglia James , Barnett Susan , Cristillo Anthony D. , Weiss Deborah , Galmin Lindsey , Ding Song , Heeney Jonathan L. , Esteban Mariano , Wagner Ralf , Pantaleo Giuseppe , Jacobs Bertram L.
Published: November 2018

Though the RV144 phase III clinical trial showed promise that an effective vaccine against HIV-1 is possible, a successful vaccine will require improvement over the vaccine candidate (ALVAC) used in the RV144 study. With that goal in mind, we have tested in nonhuman primates an attenuated but replication-competent vector, NYVAC-KC, in direct comparison to its parental vector, NYVAC, which is replication restricted in human cells, similar to the ALVAC vector used in RV144. We have utilized a prime-boost regimen for administration of the vaccine candidate that is similar to the one used in the RV144 study. The results of this study indicate that a replication-competent poxvirus vector may improve upon the effectiveness of the RV144 clinical trial vaccine candidate.
Ubiquitination Is Essential for Avibirnavirus Replication by Supporting VP1 Polymerase Activity
Authors: Wu Huansheng , Shi Liuyuan , Zhang Yina , Peng Xiran , Zheng Tuyuan , Li Yahui , Hu Boli , Zheng Xiaojuan , Zhou Jiyong
Published: November 2018

Avibirnavirus protein VP1, the RNA-dependent RNA polymerase, is responsible for IBDV genome replication, gene expression, and assembly. However, little is known about its chemical modification relating to its polymerase activity. In this study, we revealed the molecular mechanism of ubiquitin modification of VP1 via a K63-linked ubiquitin chain during infection. Lysine (K) residue 751 at the C terminus of VP1 is the target site for ubiquitin, and its ubiquitination is independent of VP1’s interaction with VP3 and eukaryotic initiation factor 4A II. The K751 ubiquitination promotes the polymerase activity of VP1 and unubiquitinated VP1 mutant IBDV significantly impairs virus replication. We conclude that VP1 is the ubiquitin-modified protein and reveal the mechanism by which VP1 promotes avibirnavirus replication.