Comparative study of mechanical-electrical-thermal responses of pouch,cylindrical, and prismatic lithium-ion cells under mechanical abuse

In the study, mechanical abuse tests mainly in the form of indentation were performed on the cylindrical cell, pouch cell, and prismatic cell. The mechanical force-displacement response, open circuit voltage (OCV), and temperature distribution were recorded and compared. In spherical head indentation tests of the pouch and prismatic cell and lateral indentation of the cylindrical cell, the peak force is strongly correlated with OCV drop and local temperature increase. However, in flat-end cylinder indentation tests, the internal mechanical damage is progressively developed, and the OCV drop and the temperature increase occur before the peak force. The fracture surfaces of the post-mortem samples were examined to investigate the correlation between fracture patterns and internal short circuit (ISC) behaviors (OCV and temperature distribution). Two distinct fracture patterns were observed that the in-plane fracture induced by biaxial stretching and inter-layers’ fracture induced by shearing. A strong correlation is observed between the number of shear fractures and OCV drop. An increase in the number of inter-layers’ fractures increases the rate of OCV drop. Additionally, the fracture patterns influence the ISC area and location, thereby affecting the heat generation and conduction as well as the temperature distribution.     

A computational framework for automating generation of sizing function in assembly meshing via disconnected skeletons

This paper proposes a framework for generating mesh sizing functions for assembly models. Size control is crucial in obtaining a high-quality mesh with a reduced number of elements. The reduction in the number of elements will decrease computation time and memory use during mesh generation and analysis. The framework consists of a background octree lattice for storing the sizing function, a set of source entities for providing sizing information based on geometric information, and an interpolation module for calculating the sizing on the background octree lattice using the source entities. Source entities are generated by performing a detailed systematic study to identify all the geometric factors of an assembly. Disconnected skeletons are extracted and used as tools to measure 3D proximity and 2D proximity, which are two of the geometric factors. The framework facilitates the generation of a variety of meshes with a low computational cost, to meet industry needs. The framework has been tested on many industrial parts, and sizing control on a few typical assemblies has been presented to demonstrate the effectiveness of the proposed framework.     

Multiscale modeling of elastic properties of cortical bone

We model cortical bone as a composite material with hierarchical structure. At a nanostructural level, bone is composed of cross-linked collagen molecules, containing water and non-collagenous proteins in their gaps, reinforced with hydroxyapatite-like nanocrystals. Such a nanocomposite structure represents a mineralized collagen fibril, which serves as a primary building block of bone. At a sub-microstructural level (few microns), the mineralized collagen fibrils are embedded in an extrafibrillar hydroxyapatite matrix to form a single lamella, which also contains the lacunar cavities. At a microstructural level (hundreds of microns) one can distinguish two lamellar structures in the mature cortical bone: osteons, made of concentric layers of lamellae surrounding long hollow Haversian canals, and interstitial lamellae made of remnants of old osteons. At a mesostructural level (several millimeters), the cortical bone is represented by a random collection of osteons and resorption cavities in the interstitial lamellae. A macrostructural level is the whole bone level containing both the cortical (compact) and trabecular (spongy) bone types. In this paper, we predict analytically the effective elastic constants of cortical bone by modeling its elastic response at these different scales, spanning from the nanostructural to mesostructural levels, using micromechanics methods and composite materials laminate theories. The results obtained at a lower scale serve as inputs for the modeling at a higher scale. The predictions are in good agreement with the experimental data reported in literature.     

High-blocking-voltage UMOSFETs with reformed electric field distribution

A high-performance vertical GaN metal–oxide–semiconductor field-effect transistor (MOSFET) with a U-shaped gate (UMOSFET) and high blocking voltage is proposed. The main concept behind this work is to reform the electric field distribution to achieve high blocking voltage. The proposed structure includes p-regions in the drift region, which we call reformed electric field (REF) regions. Simulations using the two-dimensional SILVACO simulator reveal the optimum doping concentration, and width and height of the REF regions to achieve the maximum depletion region at the breakdown voltage in the drift region. Also, the electric field distribution in the REF-UMOSFET is reformed by producing additional peaks, which decreases the common peaks under the gate trench. We discuss herein the impact of the height, width, and doping concentration of the REF regions on the ON-resistance (R_ON) and blocking voltage. The blocking voltage, specific ON-resistance, and figure of merit \( \left( {{\text{FOM}} = \frac{{V_{{{\text{BR}}}}^{2} }}{{R_{{{\text{ON}}}} }}} \right) \) are 1140 V, 0.587 mΩ cm² (V_GS = 15 V, V_DS = 1 V), and 2.214 GW/cm², respectively. The blocking voltage and FOM are increased by about 72 % and 171 % in comparison with a conventional UMOSFET (C-UMOSFET).     

A review on the micro- and nanoporous polymeric foams: Preparation and properties

A great number of studies on new synthetic materials have been focused on the preparation of different porous polymers. This review explains the principles and techniques of polymeric foam formation and their features followed by an overview of papers on polymeric porous materials. Physical blowing agent, phase separation, leaching, etching, and thermal decomposition are the main techniques for foam formation that are briefly described. This discussion covers different polymeric foams with various morphologies, pore sizes, and properties. These polymeric foams can be applied for various purposes, including tissue engineering, membranes in separation process, electrical and thermal insulators, packaging, and scaffolds.     

Energy Metabolites as Biomarkers in Ischemic and Dilated Cardiomyopathy

With more than 25 million people affected, heart failure (HF) is a global threat. As energy production pathways are known to play a pivotal role in HF, we sought here to identify key metabolic changes in ischemic- and non-ischemic HF by using a multi-OMICS approach. Serum metabolites and mRNAseq and epigenetic DNA methylation profiles were analyzed from blood and left ventricular heart biopsy specimens of the same individuals. In total we collected serum from n = 82 patients with Dilated Cardiomyopathy (DCM) and n = 51 controls in the screening stage. We identified several metabolites involved in glycolysis and citric acid cycle to be elevated up to 5.7-fold in DCM (p = 1.7 × 10⁻⁶). Interestingly, cardiac mRNA and epigenetic changes of genes encoding rate-limiting enzymes of these pathways could also be found and validated in our second stage of metabolite assessment in n = 52 DCM, n = 39 ischemic HF and n = 57 controls. In conclusion, we identified a new set of metabolomic biomarkers for HF. We were able to identify underlying biological cascades that potentially represent suitable intervention targets.     

Controlled Preparation and Characterization of Nigella Sativa Electrospun Pad for Controlled Release

Silicon - Nigella sativa (NS) oil is an anti-inflammatory agent in the traditional medicine. In the present study, novel electrospun mats contained NS oil/polyacrylonitrile as a sustained release...     

Synthesis of silica aerogel thin sheets and evaluation of its thermal,electrical, and mechanical properties

Silica aerogels are excellent thermal and acoustic insulators because of interconnected open nanopores with more than 90% porosity and higher surface area. Silica aerogel is derived by sol-gel process and dried under super-critical, sub-critical or ambient pressure conditions. Thin silica aerogel sheets could be effective thermal insulators but high fragility hinders the wider applications. We have successfully developed a synthesis method for thin, flexible, and non-fragile aerogel sheets with excellent hydrophobicity, lower thermal conductivity, and non-combustible properties via ambient drying method. The silica aerogel sheets prepared compose of silica aerogel powder, fiber glass chopped strands, and solvent-based binder. Aerogel thin insulation sheets of thickness 164 μm were prepared by pressing through rollers using aerogel paste composed of aerogel powder, fiber glass strands, and binders. The thermal conductivity values obtained were between 0.02~0.63 W/mK at temperature 25~400°C, contact angle θ = 121‘_, weight loss 3.91% when heated up to 800°C in air, dielectric voltage breakdown 3.67 kV, dielectric strength 6.37 kV/mm and tensile strength of 2.65 N/mm². The overall thermal, electrical, and mechanical evaluation of aerogel thin insulation sheet showed they have higher potential to replace existing thick and bulky aerogel composites as thermal and electrical insulators in aviation, automobiles, electronics, and high power batteries.     

Interaction dynamics of a spherical particle with a suspended liquid film

Hydrodynamics of collision interactions between a particle and gas‐liquid interface such as droplet/film is of keen interest in many engineering applications. The collision interaction between a suspended liquid (water) film of thickness 3.41 ± 0.04 mm and an impacting hydrophilic particle (glass ballotini) of different diameters (1.1–3.0 mm) in low particle impact Weber number ( ) range (1.4–33) is reported. Two distinct outcomes were observed—particle retention in the film at lower Weber number and complete penetration of the film toward higher Weber number cases. A collision parameter was defined based on energy balance approach to demarcate these two interaction regimes which agreed reasonably well with the experimental outcomes. It was shown that the liquid ligament forming in the complete penetration cases breaks up purely by “dripping/end pinch‐off” mechanism and not due to capillary wave instability. An analytical model based on energy balance approach was proposed to determine the liquid mass entrainment associated with the ligament which compared well with the experimental measurements. A good correlation between the %film mass entrained and the particle Bond number ( ) was obtained which indicated a dependency of Bo^1.72. Computationally, a three‐dimensional CFD model was developed to simulate these interactions using different contact angle boundary conditions which in general showed reasonable agreement with experiment but also indicated deficiency of a constant contact angle value to depict the interaction physics in entirety. The computed force profiles from computational fluid dynamics (CFD) model suggest dominance of the pressure force over the viscous force almost by an order of magnitude in all the Weber number cases studied. © 2015 American Institute of Chemical Engineers AIChE J, 62: 295–314, 2016     

N ‐acetylcysteine–PLGA nano‐conjugate: effects on cellular toxicity and uptake of gadopentate dimeglumine

Gadolinium as a contrast agent in MRI technique combined with DTPA causes contrast induced nephropathy (CIN) and nephrogenic systemic fibrosis (NSF) which can reduce by usage of antioxidants such as N‐acetyl cysteine by increasing the membrane''s permeability leads to lower cytotoxicity. In this study, N ‐acetyl cysteine‐PLGA Nano‐conjugate was synthesized according to stoichiometric rules of molar ratios andafter assessment by FTIR, NMR spectroscopy and Atomic Force Microscopy (AFM) imaging was combined with Magnevist® (gadopentetate dimeglumine) and its effects on the renal cells were evaluated. MTT [3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐Diphenyltetrazolium Bromide] and cellular uptake assays have indicated relatively significant toxicity of magnevist (P  < 0.05) on three cell lines including HEK293, MCF7 and L929 compared to other synthesized ligands that shown no toxicity. Moreover, systemic evaluation has shown no notable changes of blood urea nitrogen (BUN) and creatinine in kidney of mice. In consequence, antioxidant effect was increased as well as the renal toxicity of the contrast agent reduced at the cell level. As a result, PLGA‐NAC nano‐conjugate can be a promising choice for decreasing the magnevist toxicity for treatment and prevention of CIN and will be able to open a new horizon to research on reduction of toxicity of contrast agents by using nanoparticles.Inspec keywords: blood, toxicology, nanofabrication, cellular biophysics, biomedical materials, nanoparticles, chromatography, cancer, biodegradable materials, biomedical MRI, kidney, pH, nanomedicine, patient treatment, diseases, atomic force microscopy, Fourier transform infrared spectraOther keywords: cellular toxicity, gadopentate dimeglumine, contrast agent, magnetic resonance imaging technique, diethylenetriamine pentaacetate, contrast‐induced nephropathy, nephrogenic systemic fibrosis, stoichiometric rules, molar ratios, dimethyl sulphoxide solution, chromatography techniques, nuclear magnetic resonance spectroscopy, atomic force microscopy imaging, Magnevist®, gadopentetate dimeglumine, renal cells, MTT cytotoxicity, human embryonic kidney‐293, L929 cell lines, in vitro conditions, cellular uptake assays, Magnevist uptake, antioxidant effect, renal toxicity, cell level, PLGA nanocarrier, acetylcysteine nanoconjugate, Magnevist toxicity, N‐acetylcysteine–PLGA nano‐conjugate, N‐acetyl cysteine‐poly‐lactic‐co‐glycolic acid nanoconjugate