Discrete mesoscopic modeling for the simulation of woven-fabric reinforcement forming

A discrete modeling approach is proposed to simulate woven-fabric reinforcement forming via explicit finite element analysis. The tensile behaviour of the yarns is modeled by truss, beam or seatbelt elements, and the shearing behaviour of the fabric is incorporated within shell or membrane elements. This method is easy to set up using the user-defined material subroutine capabilities of explicit finite element programs. In addition, the determination of the material parameters is straightforward from conventional tensile and shear-frame tests. The proposed approach has been implemented in the ABAQUS and LS-DYNA explicit finite element programs. Two types of fabric, a plain-weave and a twill-weave Twintex® (commingled polypropylene and glass fibres) were characterized and used to validate the modeling approach. For this validation, shear-frame and bias-extension tests have been modeled, and the finite element results are compared to experimental data. The determination of experimental shear angle contours was possible via Digital Image Correlation (DIC). The finite element results from ABAQUS and LS-DYNA are similar and agree well with the experimental data. As an example of the capabilities of the method, the deep drawing of a hemisphere is simulated using both finite elements programs.     

Metabolomic profiling of beer reveals effect of temperature on non-volatile small molecules during short-term storage

The effect of temperature on non-volatile compounds in beer has not been well characterised during storage. Here, a metabolomics approach was applied to characterise the effect of storage temperature on non-volatile metabolite variation after 16weeks of storage, using fresh beer as a control. The metabolite profile of room temperature stored (RT) and cold temperature stored (CT) beer differed significantly from fresh, with the most substantial variation observed between RT and fresh beer. Metabolites that changed during storage included prenylated flavonoids, purines, and peptides, and all showed reduced quantitative variation under the CT storage conditions. Corresponding sensory panel observations indicated significant beer oxidation after 12 and 16weeks of storage, with higher values reported for RT samples. These data support that temperature affected beer oxidation during short-term storage, and reveal 5-methylthioadenosine (5-MTA) as a candidate non-volatile metabolite marker for beer oxidation and staling.     

Measuring children's perceptions of their mother's depression: The Children’s Perceptions of Others’ Depression Scale–Mother Version.

Several theoretical perspectives suggest that knowledge of children's perceptions of and beliefs about their parents' depression may be critical for understanding its impact on children. This paper describes the development and preliminary evidence for the psychometric properties of a new measure, the Children's Perceptions of Others' Depression – Mother Version (CPOD-MV), which assesses theoretically and empirically driven constructs related to children's understanding and beliefs about their mothers' depression. These constructs include children's perceptions of the severity, chronicity, and impairment of their mothers' depression; self-blame for their mother's depression; and beliefs about their abilities to deal with their mother's depression. The CPOD-MV underwent two stages of development: (1) a review of the literature to identify key constructs, focus groups to help generate items, and clinicians' ratings on the relevance and comprehensibility of the drafted items and (2) a study of the measure's psychometric properties. The literature review, focus groups, and item-reduction techniques yielded a 21-item measure. Reliability, factor structure, and discriminant, convergent, and concurrent validity were tested in a sample of 10- to 17-year-old children whose mothers had been treated for depression. The scale had good internal consistency; factor structure suggestive of a single construct; and discriminant, concurrent, convergent, and incremental validity, suggesting the importance of measuring children's perceptions of their mothers' depression beyond knowledge of mothers' depression symptom level when explaining which children have the greatest risk for emotional and behavioral problems among children of depressed mothers. These findings support continued development and beginning clinical applications of the scale. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Collective cell guidance by cooperative intercellular forces

Cells comprising a tissue migrate as part of a collective. How collective processes are coordinated over large multi-cellular assemblies has remained unclear, however, because mechanical stresses exerted at cell-cell junctions have not been accessible experimentally. We report here maps of these stresses within and between cells comprising a monolayer. Within the cell sheet there arise unanticipated fluctuations of mechanical stress that are severe, emerge spontaneously, and ripple across the monolayer. Within that stress landscape, local cellular migrations follow local orientations of maximal principal stress. Migrations of both endothelial and epithelial monolayers conform to this behaviour, as do breast cancer cell lines before but not after the epithelial-mesenchymal transition. Collective migration in these diverse systems is seen to be governed by a simple but unifying physiological principle: neighbouring cells join forces to transmit appreciable normal stress across the cell-cell junction, but migrate along orientations of minimal intercellular shear stress.     

Thermomechanical analysis and durability of commercial micro-porous polymer Li-ion battery separators

Static and dynamic thermomechanical analysis was performed with a dynamic mechanical analyzer (DMA) to identify thermal and mechanical transitions for commercially available polymer separators under mechanical loading. Clear transitions in deformation mode were observed at elevated temperatures. These transitions identified the onset of separator “shutdown” which occurred at temperatures below the polymer melting point. Mechanical loading direction was critical to the overall integrity of the separator. Anisotropic separators (Celgard 2320, 2400 and 2500) were mechanically limited when pulled in tensile in the transverse direction. The anisotropy of these separators is a result of the dry technique used to manufacture the micro-porous membranes. Separators prepared using the wet technique (Entek Gold LP) behaved more uniformly, or biaxially, where all mechanical properties were nearly identical within the separator plane. The information provided by the DMA can also be useful for predicting the long-term durability of polymer separators in lithium-ion batteries exposed to electrolyte (solvent and salt), thermal fluctuations and electrochemical cycling. Small losses in mechanical integrity were observed for separators exposed to the various immersion environments over the 4-week immersion time.     

Human DDX17 Unwinds Rift Valley Fever Virus Non-Coding RNAs

Rift Valley fever virus (RVFV) is a mosquito-transmitted virus from the Bunyaviridae family that causes high rates of mortality and morbidity in humans and ruminant animals. Previous studies indicated that DEAD-box helicase 17 (DDX17) restricts RVFV replication by recognizing two primary non-coding RNAs in the S-segment of the genome: the intergenic region (IGR) and 5′ non-coding region (NCR). However, we lack molecular insights into the direct binding of DDX17 with RVFV non-coding RNAs and information on the unwinding of both non-coding RNAs by DDX17. Therefore, we performed an extensive biophysical analysis of the DDX17 helicase domain (DDX17_135–555) and RVFV non-coding RNAs, IGR and 5’ NCR. The homogeneity studies using analytical ultracentrifugation indicated that DDX17_135–555, IGR, and 5’ NCR are pure. Next, we performed small-angle X-ray scattering (SAXS) experiments, which suggested that DDX17 and both RNAs are homogenous as well. SAXS analysis also demonstrated that DDX17 is globular to an extent, whereas the RNAs adopt an extended conformation in solution. Subsequently, microscale thermophoresis (MST) experiments were performed to investigate the direct binding of DDX17 to the non-coding RNAs. The MST experiments demonstrated that DDX17 binds with the IGR and 5’ NCR with a dissociation constant of 5.77 ± 0.15 µM and 9.85 ± 0.11 µM, respectively. As DDX17_135–555 is an RNA helicase, we next determined if it could unwind IGR and NCR. We developed a helicase assay using MST and fluorescently-labeled oligos, which suggested DDX17_135–555 can unwind both RNAs. Overall, our study provides direct evidence of DDX17_135–555 interacting with and unwinding RVFV non-coding regions.     

Structural Aspects and Prediction of Calmodulin-Binding Proteins

Calmodulin (CaM) is an important intracellular protein that binds Ca²⁺ and functions as a critical second messenger involved in numerous biological activities through extensive interactions with proteins and peptides. CaM’s ability to adapt to binding targets with different structures is related to the flexible central helix separating the N- and C-terminal lobes, which allows for conformational changes between extended and collapsed forms of the protein. CaM-binding targets are most often identified using prediction algorithms that utilize sequence and structural data to predict regions of peptides and proteins that can interact with CaM. In this review, we provide an overview of different CaM-binding proteins, the motifs through which they interact with CaM, and shared properties that make them good binding partners for CaM. Additionally, we discuss the historical and current methods for predicting CaM binding, and the similarities and differences between these methods and their relative success at prediction. As new CaM-binding proteins are identified and classified, we will gain a broader understanding of the biological processes regulated through changes in Ca²⁺ concentration through interactions with CaM.