This study demonstrates that trace boron addition to Ti–6Al–4V coupons produced by additive layer manufacturing is an effective way to eliminate the deleterious anisotropic microstructures often ...encountered with this manufacturing technique. Trace boron additions (up to 0.13wt.%) to this alloy eliminate grain boundary-α and colony-α, and instead produce a homogeneous α-microstructure consisting of fine equiaxed α-grains in both as-deposited and heat treated coupons. Prior-β grains remain columnar with boron addition but become narrower due to the wider solidification range and growth restricting effect of the boron solute. Compared to unmodified Ti–6Al–4V alloy, Ti–6Al–4V modified with trace boron additions showed up to 40% improvement in plasticity with no loss in strength under uniaxial compression at room temperature. Boron additions were found to inhibit twinning transmission that causes sudden large load drops during deformation of the unmodified Ti–6Al–4V alloy in the heat treated condition.
Mitochondrial DNA copy number (mtDNA-CN), a measure of the number of mitochondrial genomes per cell, is a minimally invasive proxy measure for mitochondrial function and has been associated with ...several aging-related diseases. Although quantitative real-time PCR (qPCR) is the current gold standard method for measuring mtDNA-CN, mtDNA-CN can also be measured from genotyping microarray probe intensities and DNA sequencing read counts. To conduct a comprehensive examination on the performance of these methods, we use known mtDNA-CN correlates (age, sex, white blood cell count, Duffy locus genotype, incident cardiovascular disease) to evaluate mtDNA-CN calculated from qPCR, two microarray platforms, as well as whole genome (WGS) and whole exome sequence (WES) data across 1,085 participants from the Atherosclerosis Risk in Communities (ARIC) study and 3,489 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). We observe mtDNA-CN derived from WGS data is significantly more associated with known correlates compared to all other methods (p < 0.001). Additionally, mtDNA-CN measured from WGS is on average more significantly associated with traits by 5.6 orders of magnitude and has effect size estimates 5.8 times more extreme than the current gold standard of qPCR. We further investigated the role of DNA extraction method on mtDNA-CN estimate reproducibility and found mtDNA-CN estimated from cell lysate is significantly less variable than traditional phenol-chloroform-isoamyl alcohol (p = 5.44x10-4) and silica-based column selection (p = 2.82x10-7). In conclusion, we recommend the field moves towards more accurate methods for mtDNA-CN, as well as re-analyze trait associations as more WGS data becomes available from larger initiatives such as TOPMed.
The compartmentation of neutral lipids in plants is mostly associated with seed tissues, where triacylglycerols (TAGs) stored within lipid droplets (LDs) serve as an essential physiological energy ...and carbon reserve during postgerminative growth. However, some nonseed tissues, such as leaves, flowers and fruits, also synthesize and store TAGs, yet relatively little is known about the formation or function of LDs in these tissues. Characterization of LD-associated proteins, such as oleosins, caleosins, and sterol dehydrogenases (steroleosins), has revealed surprising features of LD function in plants, including stress responses, hormone signaling pathways, and various aspects of plant growth and development. Although oleosin and caleosin proteins are specific to plants, LD-associated sterol dehydrogenases also are present in mammals, and in both plants and mammals these enzymes have been shown to be important in (steroid) hormone metabolism and signaling. In addition, several other proteins known to be important in LD biogenesis in yeasts and mammals are conserved in plants, suggesting that at least some aspects of LD biogenesis and/or function are evolutionarily conserved.
TASK COMPLEXITY: EXTENDING A CORE CONCEPT HÆREM, THORVALD; PENTLAND, BRIAN T.; MILLER, KENT D.
The Academy of Management review,
07/2015, Letnik:
40, Številka:
3
Journal Article
Recenzirano
We reexamine the assumptions of current theory to update and extend the concept of task complexity to tasks that include multiple actors at any level of analysis. Tasks can be modeled as networks of ...required actions and information cues carried out or processed by particular actors. Counting pathways in the task network provides an index of task complexity that incorporates insights from organization research but is more consistent with contemporary complexity science than prior approaches and better reflects the exponential nature of the phenomenon. The revised concept of task complexity can be readily used as an independent or dependent variable, and it can be used to compare observed and idealized descriptions of tasks. We discuss its implications for developing theory.
Biogenesis and functions of lipid droplets in plants Chapman, Kent D.; Dyer, John M.; Mullen, Robert T.
Journal of lipid research,
February 2012, 2012-02-00, 2012-02-01, Letnik:
53, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The compartmentation of neutral lipids in plants is mostly associated with seed tissues, where triacylglycerols (TAGs) stored within lipid droplets (LDs) serve as an essential physiological energy ...and carbon reserve during postgerminative growth. However, some nonseed tissues, such as leaves, flowers and fruits, also synthesize and store TAGs, yet relatively little is known about the formation or function of LDs in these tissues. Characterization of LD-associated proteins, such as oleosins, caleosins, and sterol dehydrogenases (steroleosins), has revealed surprising features of LD function in plants, including stress responses, hormone signaling pathways, and various aspects of plant growth and development. Although oleosin and caleosin proteins are specific to plants, LD-associated sterol dehydrogenases also are present in mammals, and in both plants and mammals these enzymes have been shown to be important in (steroid) hormone metabolism and signaling. In addition, several other proteins known to be important in LD biogenesis in yeasts and mammals are conserved in plants, suggesting that at least some aspects of LD biogenesis and/or function are evolutionarily conserved.
Dilated cardiomyopathy (DCM) is an important cause of heart failure and the leading indication for heart transplantation. Many rare genetic variants have been associated with DCM, but common variant ...studies of the disease have yielded few associated loci. As structural changes in the heart are a defining feature of DCM, we report a genome-wide association study of cardiac magnetic resonance imaging (MRI)-derived left ventricular measurements in 36,041 UK Biobank participants, with replication in 2184 participants from the Multi-Ethnic Study of Atherosclerosis. We identify 45 previously unreported loci associated with cardiac structure and function, many near well-established genes for Mendelian cardiomyopathies. A polygenic score of MRI-derived left ventricular end systolic volume strongly associates with incident DCM in the general population. Even among carriers of TTN truncating mutations, this polygenic score influences the size and function of the human heart. These results further implicate common genetic polymorphisms in the pathogenesis of DCM.
Investigating behavioral explanations for the timing of corporate acquisitions, we focus on the effects of performance relative to aspiration level, slack, and proximity to bankruptcy. We used event ...history modeling to explain the hazard of acquisitions among U.S. manufacturing firms from 1980 to 2000. Results indicate acquisition activity increases as performance rises among firms performing below aspirations, but falls among firms performing above aspirations. Slack has a positive relation with acquisitions, and financial distress inhibits acquisitions. We also found support for shifts in firms' focus of attention between survival, aspirations, and slack.
Purpose: The aim of this study was to conduct a scoping review of research on oral and laryngeal diadochokinesis (DDK) in children and adults, either typically developing/developed or with a clinical ...diagnosis. Method: Searches were conducted with PubMed/MEDLINE, Google Scholar, CINAHL, and legacy sources in retrieved articles. Search terms included the following: DDK, alternating motion rate, maximum repetition rate, sequential motion rate, and syllable repetition rate. Results: Three hundred sixty articles were retrieved and included in the review. Data source tables for children and adults list the number and ages of study participants, DDK task, and language(s) spoken. Cross-sectional data for typically developing children and typically developed adults are compiled for the monosyllables /popen-mid back unrounded vowel/, /topen-mid back unrounded vowel/, and /kopen-mid back unrounded vowel/; the trisyllable /popen-mid back unrounded voweltopen-mid back unrounded vowelkopen-mid back unrounded vowel/; and laryngeal DDK. In addition, DDK results are summarized for 26 disorders or conditions. Discussion: A growing number of multidisciplinary reports on DDK affirm its role in clinical practice and research across the world. Atypical DDK is not a well-defined singular entity but rather a label for a collection of disturbances associated with diverse etiologies, including motoric, structural, sensory, and cognitive. The clinical value of DDK can be optimized by consideration of task parameters, analysis method, and population of interest.
Incorporation of silver nanoparticles (AgNPs) into an increasing number of consumer products has led to concern over the potential ecological impacts of their unintended release to the environment. ...Dissolution is an important environmental transformation that affects the form and concentration of AgNPs in natural waters; however, studies on AgNP dissolution kinetics are complicated by nanoparticle aggregation. Herein, nanosphere lithography (NSL) was used to fabricate uniform arrays of AgNPs immobilized on glass substrates. Nanoparticle immobilization enabled controlled evaluation of AgNP dissolution in an air-saturated phosphate buffer (pH 7.0, 25 °C) under variable NaCl concentrations in the absence of aggregation. Atomic force microscopy (AFM) was used to monitor changes in particle morphology and dissolution. Over the first day of exposure to ≥10 mM NaCl, the in-plane AgNP shape changed from triangular to circular, the sidewalls steepened, the in-plane radius decreased by 5–11 nm, and the height increased by 6–12 nm. Subsequently, particle height and in-plane radius decreased at a constant rate over a 2-week period. Dissolution rates varied linearly from 0.4 to 2.2 nm/d over the 10–550 mM NaCl concentration range tested. NaCl-catalyzed dissolution of AgNPs may play an important role in AgNP fate in saline waters and biological media. This study demonstrates the utility of NSL and AFM for the direct investigation of unaggregated AgNP dissolution.
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