bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of extracorporeal membrane oxygenation in pediatric abdominal transplant patients: A qualitative systematic review of literature
Authors: Reid Trista D. , Kratzke Ian , Dayal Diana , Raff Lauren , Kumar Aman , Phillips Michael R. , Carlson Rebecca , Desai Chirag S. 
Published: December 2020

AbstractBackgroundAdvances in ECMO have made it a useful adjunct in critically ill pediatric patients; however, a dearth of evidence exists regarding risks and benefits in pediatric abdominal transplantation. The purpose of this study was to perform a qualitative systematic review of outcomes in pediatric patients undergoing ECMO support pre– or post–abdominal organ transplantation.MethodsThis was a systematic review conducted from Jan 1, 1989, to April 24, 2020, via PubMed, Embase, Scopus, Web of Science, the Cochrane Library, and ClinicalTrials.gov of all pediatric solid abdominal organ transplant recipients (pre‐ and post‐transplant) and donors who underwent V‐A or V‐V ECMO cannulation. Death was the primary outcome, with graft function and complications as secondary outcomes.ResultsFourteen articles were identified that fit criteria, with 88% being case reports. Three patients were donors placed on ECMO, with no mortality among the 8 recipients of organs from these donors. Nineteen recipients were placed on ECMO. All were liver transplants. Most patients experienced at least one complication (84%), with bleeding as the most common cause (44%). Mortality was 26%. Causes of death included multiorgan system failure (n = 3), heart failure (n = 1), Systemic inflammatory response syndrome (n = 1), abdominal compartment syndrome (n = 3), bleeding (n = 1), septic shock from aspergillus (n = 1), and hepatic artery thrombosis (n = 2).ConclusionsThe data are poor on ECMO usage in pediatric abdominal transplantation. While complications were high, mortality did not appear to be related to ECMO usage and was relatively low given the severity of patient illness.
Nucleolar rDNA folds into condensed foci with a specific combination of epigenetic marks
Authors: Kutashev Konstantin O. , Franek Michal , Diamanti Klev , Komorowski Jan , Olšinová Marie , Dvořáčková Martina 
Published: December 2020

SUMMARYArabidopsis thaliana 45S ribosomal genes (rDNA) are located in tandem arrays called nucleolus organizing regions on the termini of chromosomes 2 and 4 (NOR2 and NOR4) and encode rRNA, a crucial structural element of the ribosome. The current model of rDNA organization suggests that inactive rRNA genes accumulate in the condensed chromocenters in the nucleus and at the nucleolar periphery, while the nucleolus delineates active genes. We challenge the perspective that all intranucleolar rDNA is active by showing that a subset of nucleolar rDNA assembles into condensed foci marked by H3.1 and H3.3 histones that also contain the repressive H3K9me2 histone mark. By using plant lines containing a low number of rDNA copies, we further found that the condensed foci relate to the folding of rDNA, which appears to be a common mechanism of rDNA regulation inside the nucleolus. The H3K9me2 histone mark found in condensed foci represents a typical modification of bulk inactive rDNA, as we show by genome‐wide approaches, similar to the H2A.W histone variant. The euchromatin histone marks H3K27me3 and H3K4me3, in contrast, do not colocalize with nucleolar foci and their overall levels in the nucleolus are very low. We further demonstrate that the rDNA promoter is an important regulatory region of the rDNA, where the distribution of histone variants and histone modifications are modulated in response to rDNA activity.
Influence of Ambient Pressure and Heating Power on the Thermal Runaway Features of Lithium-Ion Battery
Authors: Chen Xiantao , Zhang Xu , Wang Haibin , Jia Jingyun , Xie Song , Zhi Maoyong , Fu Ju , Sun Qiang 
Published: December 2020

Abstract
The thermal runaway hazards pose a serious threat to the application and transport of lithium-ion batteries on the aircraft. Hence, the researches of thermal safety in flight condition are necessary. In this study, the tests were conducted in a dynamic pressure chamber to study the effects of ambient pressure and heating power on the thermal runaway characteristics. The results show that the fierce behaviors of jet fire, deflagration, and explosion only were observed in high ambient pressure with high heating power. The open time of the safety valve is advanced as pressure from 95 kPa to 20 kPa. The parameters of heat release rate (HRR), total heat release (THR), cell surface temperature, peak concentration of CO2, and mass loss decrease as the descend of external pressure or heating power. The peak values of hydrocarbon (CHx) and CO increase with the descent of pressure but decrease as the reduction of heating power. The effects of ambient pressure on the thermal runaway (TR) fire behaviors mainly attribute to the low oxygen density. The time of heating and smoking may account for the difference of TR behaviors with various heating power. It is revealed that the fire risk and the hazards of toxic/flammable gas emissions are tightly relative to the TR behaviors. These results provide valuable proposals and inspiration for the safety warning and hazard reduction under low pressure.
Liquid-Cooled Heat Sink Optimization for Thermal Imbalance Mitigation in Wide-Bandgap Power Modules
Authors: Sahu Raj , Gurpinar Emre , Ozpineci Burak 
Published: December 2020

Abstract
Power semiconductor die layout in substrates used in power modules is generally optimized for minimum electrical parasitics (e.g., stray inductance) by considering the minimum spacing between dies for thermal decoupling. The layout assumes sufficient heat spreading and transfer from dies to the cooling structure. For module designs using a direct substrate cooling method, the base plate is removed, leading to a steady-state thermal asymmetry in the power module due to insufficient heat spreading/transfer. This causes significant temperature differences among the devices. Such unintentional thermal asymmetries can lead to undesirable asymmetries in power conversion among semiconductor devices, which impact reliability. This article proposes a thermal imbalance mitigation method that uses evolutionary optimized liquid-cooled heat sinks to improve the thermal loading among devices.
Design of Accelerated Degradation Test Method and Failure Analysis of Flexible Hybrid Electronic Devices
Authors: Davila-Frias Alex , Marinov Val , Yadav Om Prakash , Atanasov Yuriy 
Published: December 2020

Abstract
Accelerated life testing (ALT) has been a common choice to study the effects of environmental stresses on flexible hybrid electronics (FHE), a promising technology to produce flexible electronic devices. Nevertheless, accelerated degradation testing (ADT) has proven to be a more effective approach, which does not require failure occurrences, allowing shorter testing times. Since FHE devices are expected to be highly reliable, ADT provides useful information in the form of degradation data for further analysis without actual failure data. In this paper, we present the design and experimental setup of ADT for FHE considering two stress factors simultaneously. We use daisy-chain resistance as a measurable degradation characteristic to periodically monitor the degradation of FHE products under accelerated stress conditions. Two stress factors, temperature and humidity, are considered and ADT was carried out considering four combinations of temperature and humidity simultaneously. Failure analysis was performed on failed units to investigate the failure process and location of the failure. The ADT data was used to fit in the appropriate mathematical degradation model representing the failure process. The data analysis showed faster degradation paths for higher stress combinations. Finally, we present insights and further research opportunities to expand the work.
Enabling Packaging Architectures and Interconnect Technologies for Image Sensors
Authors: Lu Mei-Chien 
Published: December 2020

Abstract
Image sensors have become a crucial technology platform for many applications in the past decades. Market demands continue to grow at a fast pace accelerated by innovations, performance improvement, and new applications. Efficient package architectures and advanced interconnect technologies are among the enablers for the commercialization of image sensors. This study examines how image sensor pixel electronics design and form factor drives innovations in chip stacking and high-density interconnects. 3D chip stacking architectures for CMOS image sensors are analyzed. Cases of image sensors for imaging at visible light, single photon avalanche photodiode (SPAD) for wide dynamic range, rolling shutter and global shutter, and depth sensing and light detection and ranging (LiDAR) are explored based on the pixel electronics requirements. Interconnect methods are also explored. Wafer direct bonding followed by through silicon via (TSV) and hybrid bonding technologies have recently been implemented in the image sensor industry. The preferences and challenges of these two interconnect technologies for image sensor chip stacking are discussed. As TSV technology is relatively mature, this study includes the process flow for one example of the hybrid bonding method. Challenges and future advancement are briefed along with the outlook of the technology and market momentum of image sensors.
Comparative Study of Effective Cooling in Microchannel Heat Sinks (MCHS) With Nanofluid and Hydrophobic Nanostructures Using Computational Fluid Dynamics
Authors: Jennings Darryl , Smith Sonya 
Published: December 2020

Abstract
The goal of this research is to present an analytical model of nanostructures and study the effects of their geometry on the performance of micro channels. The pressure drop experienced by micro channels is of interest as it presents a limit on forced convection heat transfer. This work will demonstrate how the presence of nanostructures primarily affects pressure drop as well as other cooling flow characteristics. Additional work in the impact of microchannel cross-sectional geometry and friction factor formulation is provided as well. Multiple transient analyses were performed in ANSYS FLUENT to ascertain performance characteristics of microchannels without the presence of hydrophobic nanostructures. The results were compared to the analytical model developed in this study.
Effective Thermal Conductivity of Phase Change Material-Based Composites for High Heat Flux Electronic Cooling
Authors: Singh Ayushman , Rangarajan Srikanth , Choobineh Leila , Sammakia Bahgat 
Published: December 2020

Abstract
This work presents a simplified approach to optimally designing a heat sink with metallic thermal conductivity enhancers infiltrated with phase change material for electronic cooling. In present study, thermal conductivity enhancers are in the form of a honeycomb structure. A benchmarked two-dimensional computational fluid dynamics model was employed to investigate the thermal performance of the phase change material-metallic thermal conductivity enhancer composite heat sinks. Metallic thermal conductivity enhancers are often used in conjunction with phase change material to enhance the conductivity of the composite heat sink. Under constrained heat sink volume, the higher volume fraction of thermal conductivity enhancers improves the effective thermal conductivity of the composite, while it reduces the amount of latent heat storage simultaneously. The present work arrives at the optimal design of heat sink for electronic cooling by resolving the stated tradeoff. In this study, the total volume of the heat sink and the interfacial heat transfer area between the phase change material and thermal conductivity enhancers are constrained for all design points. Furthermore, assuming conduction-dominated heat transfer, an effective numerical model that solves the single energy equation with the effective properties of the phase change material- metallic thermal conductivity enhancer composite has been developed. The temperature gradient-time history is compared and matched for both the models to arrive at the accurate effective thermal conductivity value. The relationship of effective thermal conductivity as a function of metal volume fraction and thermal conductivity of metallic thermal conductivity enhancer is obtained. The figure of merit (FOM) is used to define the balance between effective thermal conductivity and energy storage capacity. The FOM is maximized to find the optimal volume fraction for the present design. The results from the study reveals that there exists an optimal metal volume fraction that maximizes the thermal performance of the composite.
An Experimental Investigation Into Frost Accumulation Over Vertical Finned and Unfinned Surfaces During Impinging Air Flow
Authors: Oksuz E. A. , Saygin A. , Basol A. M. , Budakli M. , Arik M. 
Published: December 2020

Abstract
Frost formation on evaporators negatively affects the cooling performance of refrigerators. It increases the thermal resistance between the refrigerant and air leading to a reduction in the system cooling capacity. In this study, the effect of frost accumulation over a bare and finned surface on the convective thermal resistances has been experimentally investigated under impinging flow conditions. The surfaces are vertically positioned in a horizontal wind tunnel. The convective resistances have been measured with an in-house developed heat flux measurement system. Finally, the effectiveness of the finned surface was derived from the measurements for dry, condensing flow and as well as for frosting conditions. Under frosting conditions, the effectiveness of the finned surface is measured as 1.4 that is by a factor of 2X lower compared to the effectiveness of the same finned surface operating under dry conditions. It has been observed that the frost accumulation initially takes place at the tip of the fins and leads to a 45% drop in the heat transfer rate when the fin tips are completely covered with frost. Further frost accumulation on the fin base does not result in an additional drop in the heat transfer rate. In this regard, the study emphasizes the importance of the fin tip design for the heat sinks operating under frosting conditions.
Multifunctional Magnetic Nanocomposite Encapsulant for EMI Shielding in Power Electronics
Authors: Carlton Hayden , Iradukunda Ange , Huitink David , Myane Sarah , Akey Noah , Imran Asif , Luo Fang 
Published: December 2020

Abstract
As power densities and switching frequencies dramatically increase, a potential area of advancement for encapsulant technologies is to utilize them to mitigate electromagnetic interference, which directly impacts device efficiency at high switching frequencies; one promising topic involves the creation of magnetic nanoparticle-enhanced encapsulants, with intrinsic sensitivity to electromagnetic fields that could provide additional noise shielding for power electronic devices. A nanocomposite encapsulant was created by directly incorporating magnetic iron oxide nanoparticles into a silicone matrix. The nanoparticles, with an average size of 100 nm, achieved excellent dispersion in the silicone polymer, even at high concentrations, with no additive or surfactants needed to improve stability. Material testing, including thermo mechanical analysis and thermal conductivity measurements were performed to determine if the addition of the nanoparticles altered the thermal or mechanical properties of the base silicone. The nanocomposites at different concentrations observed thermal conductivities of 0.5 W/m-K and coefficient of thermal expansions of 280 ppm/°C, which resembles that of normal silicone; however, the addition of the iron oxide reduced the dielectric breakdown strength of the silicone matrix exponentially with respect to concentration from 20 kV/mm to 3 kV/mm. Further efforts to optimize the dielectric properties of the nanocomposites with respect to the nanoparticle loading is necessary in order to directly apply this technology; however, the results indicate magnetic nanocomposites could be a potential avenue towards mitigating electromagnetic interference in power devices.
CFD Analysis on Liquid Cooled Cold Plate Using Copper Nanoparticles
Authors: Shahi Pardeep , Agarwal Sarthak , Saini Satyam , Niazmand Amirreza , Bansode Pratik , Agonafer Dereje 
Published: December 2020

Abstract
In today’s world, most data centers have multiple racks with numerous servers in each of them. The high amount of heat dissipation has become the largest server-level cooling problem for the data centers. The higher dissipation required, the higher is the total energy required to run the data center. Although still the most widely used cooling methodology, air cooling has reached its cooling capabilities especially for High-Performance Computing data centers. Liquid-cooled servers have several advantages over their air-cooled counterparts, primarily of which are high thermal mass, lower maintenance. Nano-fluids have been used in the past for improving the thermal efficiency of traditional dielectric coolants in the power electronics and automotive industry. Nanofluids have shown great promise in improving the convective heat transfer properties of the coolants due to a proven increase in thermal conductivity and specific heat capacity.
The present research investigates the thermal enhancement of the performance of de-ionized water-based dielectric coolant with Copper nanoparticles for a higher heat transfer from the server cold plates. Detailed 3-D modeling of a commercial cold plate is completed and the CFD analysis is done in a commercially available CFD code ANSYS CFX. The obtained results compare the improvement in heat transfer due to improvement in coolant properties with data available in the literature.
CFD Simulation of Two-Phase Immersion Cooling Using FC-72 Dielectric Fluid
Authors: Niazmand Amirreza , Chauhan Tushar , Saini Satyam , Shahi Pardeep , Bansode Pratik Vithoba , Agonafer Dereje 
Published: December 2020

Abstract
With more development in electronics system capable of having larger functional densities, power density is increasing. Immersion cooling demonstrates the highest power usage efficiency (PUE) among all cooling techniques for data centers and there is still interest in optimizing immersion cooling to use it to its full potential. The aim of this paper is to present the effect of inclination and thermal shadowing on two-phase immersion cooling using FC-72. For simulation of boiling, the RPI (Rensselaer Polytechnic Institute) wall boiling model has been used. Also, two empirical models were used for calculation of bubble departure diameter and nucleate site density. The boundary condition was assumed to be constant heat flux and the bath temperature was kept at boiling temperature of FC-72 and the container pressure is assumed to be atmospheric. this study showed that due to the thermal shadowing, boiling boundary layer can lay over the top chipset and increases vapor volume fraction over top chipsets. This ultimately causes increase in maximum temperature of second chip. The other main observation is with higher inclination angle of chip, maximum temperature on the chip decreases up to 3°C.
Development of a Novel Test Setup to Study the Combined Effects of Electromigration and Mechanical Stress in Solder Interconnects
Authors: Montazeri Mahsa , Huitink David R. 
Published: December 2020

Abstract
One key concern that arises from scaling of device interconnects with increasing power density requirements is electromigration (EM). On the other hand, thermal cycling fatigue has always been a reliability challenge in solder interconnects. Variations in device temperature caused by environmental or operating conditions induce stress in solders, as they usually connect two components with different coefficients of thermal expansion (CTE). These thermally induced stresses may lead to crack formation within the solders. The combination of EM effects and thermal cycling add to the complexity of the reliability estimation for high current density applications.
In this work, a novel test setup has been designed and developed to estimate the reliability of solder interconnects under high current density, while a constant tensile stress is also applied to the solder interconnect. The test set up offers the ability to test up to four samples at the same time. Additionally, the test samples are fabricated with two copper wires connected by Pb/Sn solder to imitate copper UBM in a flip-chip bonding connection. Strain in solder is measured by monitoring the elongation of the wire during testing, while failure of the connection is detected by continuous monitoring of the electrical resistance. The experiment is conducted for conditions including pure tensile stress, pure EM and coupled EM and tensile stress where a significant reduction in life-time is observed for the coupled degradation effects. Comparing the experimental results of different current densities at different stress levels will help in identifying the nature of degradation in solders, which will help inform the drive for miniaturization.
Experimental Characterization of Heat Transfer and Thermal Energy Storage Capability Using Swirling Two-Phase Flow in the Package Integrated Cyclone COoler (PICCO)
Authors: deBock Peter , Miorini Rinaldo , Hoel Cathleen , Sharar Darin , Whalen Bryan 
Published: December 2020

Abstract
The increasing demand for high power density wide-bandgap power electronics has propelled heat transfer research leading to a constant increase in the thermal performance of cold plates and heat sinks. Most of this research has focused on reducing thermal resistance of the package which can have a detrimental effect on transient thermal performance if thermal capacitance is reduced.
In order to provide both a low thermal resistance and a higher thermal capacitance integrated into the package and near the thermal junction, a new cold plate called the Package Integrated Cyclone COoler (PICCO) was developed. GE Research and the US Army Research Lab collaborated to explore and validate the potential of this concept.
The PICCO coldplate, which is enabled by 3D printing, establishes a swirling coolant flow field to remove heat. The swirling flow is anticipated to significantly aid in vapor removal from the surface and hence allow for the fluid to provide thermal capacitance through two-phase heat transfer efficiently.
This paper describes the experiment design and development for thermal storage and cooling performance characterization of PICCO. The test rig includes a high-pressure capability gear pump moving fluid first through a Coriolis flowmeter and then through PICCO, where the fluid is accelerated in the cyclone and heated by miniaturized ceramic heaters, simulating SiC power electronics. The coolant releases the accumulated enthalpy to a plate-fin heat exchanger that is connected to a chiller. Several absolute and differential pressure transducers and thermocouples monitor the state of FC-72. The experiments will provide empirical transfer functions characterizing the PICCO pressure drop, heat transfer coefficient, critical heat flux and thermal energy storage capability.