Influence of technical characteristics on the rolling shear properties of cross laminated timber by modified planar shear tests

Rolling shear properties of cross laminated timber are important mechanical properties for its structural application. To evaluate the influence of technical characteristics such as edge-gluing and gap size in the cross layers, on the measurement of rolling shear modulus and strength of cross laminated timber, three-layer spruce-pine-fire cross laminated timber shear block specimens with and without edge-gluing, with gaps of 2 mm, 4 mm and 6 mm, were tested by a modified planar shear test method. The mean values of rolling shear strength and modulus of No. 2 visual grade spruce-pine-fire cross laminated timber were 1.32 MPa and 111 MPa with coefficients of variance of 20% and 28%, respectively, regardless of technical characteristics. The characteristic rolling shear strength of all groups of three-layer cross laminated timber specimens was determined to be 0.88 MPa. The results indicated that the rolling shear strength and modulus values used in current design practice of spruce-pine-fire cross laminated timber were conservative. It was found that edge-gluing and gap size had a significant influence on measuring rolling shear strength rather than apparent rolling shear modulus by the modified planar shear test method. With the gap size larger than 2 mm, its influence on measuring rolling shear strength became negligible. The three major initial failure modes identified for the cross layer regardless of technical characteristics were rolling shear failure along the growth ring, tension perpendicular to grain failure in wood pith and tension perpendicular to grain failure along the wood ray

Embedment Strength of Cross-Laminated Timber for Smooth Dowel-type Fasteners

Embedment strength is a significant property in the dowel type connection in timber structure, i.e. cross-laminated timber (CLT). The CLT design properties are different from those of sawn timber (ST) and glued-laminated timber (GLT) because of the orthogonal structure, which may particularly have influence on the design of connections. The layup feature, i.e. the thickness ratio of transverse layer (TRTL) was considered as an effective factor on CLT embedment strength in this study, except for other factors, i.e. wood density, smooth dowel diameter, and loading angle. Approximate 660 embedment tests were performed according to ASTM D5764 half-hole test method. A few of existing design models for CLT embedment strength were evaluated using experimental data. It was found that different factors had different effect tendency and each factor had statistically significant impact on CLT embedment strength. The embedment strength and failure modes of CLT were obviously different from those of GLT due to the existence of transverse layer in CLT. The existing design equations should be improved. Based on the test results, a new design equation was proposed which had better prediction

SiO2 nanoparticles induce cytotoxicity and protein expression alteration in HaCaT cells

<p>Abstract</p> <p>Background</p> <p>Nanometer silicon dioxide (nano-SiO₂) has a wide variety of applications in material sciences, engineering and medicine; however, the potential cell biological and proteomic effects of nano-SiO₂exposure and the toxic mechanisms remain far from clear.</p> <p>Results</p> <p>Here, we evaluated the effects of amorphous nano-SiO₂(15-nm, 30-nm SiO₂). on cellular viability, cell cycle, apoptosis and protein expression in HaCaT cells by using biochemical and morphological analysis, two-dimensional differential gel electrophoresis (2D-DIGE) as well as mass spectrometry (MS). We found that the cellular viability of HaCaT cells was significantly decreased in a dose-dependent manner after the treatment of nano-SiO₂and micro-sized SiO₂particles. The IC₅₀value (50% concentration of inhibition) was associated with the size of SiO₂particles. Exposure to nano-SiO₂and micro-sized SiO₂particles also induced apoptosis in HaCaT cells in a dose-dependent manner. Furthermore, the smaller SiO₂particle size was, the higher apoptotic rate the cells underwent. The proteomic analysis revealed that 16 differentially expressed proteins were induced by SiO₂exposure, and that the expression levels of the differentially expressed proteins were associated with the particle size. The 16 proteins were identified by MALDI-TOF-TOF-MS analysis and could be classified into 5 categories according to their functions. They include oxidative stress-associated proteins; cytoskeleton-associated proteins; molecular chaperones; energy metabolism-associated proteins; apoptosis and tumor-associated proteins.</p> <p>Conclusions</p> <p>These results showed that nano-SiO₂exposure exerted toxic effects and altered protein expression in HaCaT cells. The data indicated the alterations of the proteins, such as the proteins associated with oxidative stress and apoptosis, could be involved in the toxic mechanisms of nano-SiO₂exposure.</p

High-resolution myelin-water fraction and quantitative relaxation mapping using 3D ViSTa-MR fingerprinting

Purpose: This study aims to develop a high-resolution whole-brain multi-parametric quantitative MRI approach for simultaneous mapping of myelin-water fraction (MWF), T1, T2, and proton-density (PD), all within a clinically feasible scan time. Methods: We developed 3D ViSTa-MRF, which combined Visualization of Short Transverse relaxation time component (ViSTa) technique with MR Fingerprinting (MRF), to achieve high-fidelity whole-brain MWF and T1/T2/PD mapping on a clinical 3T scanner. To achieve fast acquisition and memory-efficient reconstruction, the ViSTa-MRF sequence leverages an optimized 3D tiny-golden-angle-shuffling spiral-projection acquisition and joint spatial-temporal subspace reconstruction with optimized preconditioning algorithm. With the proposed ViSTa-MRF approach, high-fidelity direct MWF mapping was achieved without a need for multi-compartment fitting that could introduce bias and/or noise from additional assumptions or priors. Results: The in-vivo results demonstrate the effectiveness of the proposed acquisition and reconstruction framework to provide fast multi-parametric mapping with high SNR and good quality. The in-vivo results of 1mm- and 0.66mm-iso datasets indicate that the MWF values measured by the proposed method are consistent with standard ViSTa results that are 30x slower with lower SNR. Furthermore, we applied the proposed method to enable 5-minute whole-brain 1mm-iso assessment of MWF and T1/T2/PD mappings for infant brain development and for post-mortem brain samples. Conclusions: In this work, we have developed a 3D ViSTa-MRF technique that enables the acquisition of whole-brain MWF, quantitative T1, T2, and PD maps at 1mm and 0.66mm isotropic resolution in 5 and 15 minutes, respectively. This advancement allows for quantitative investigations of myelination changes in the brain.Comment: 38 pages, 12 figures and 1 tabl

Association of serum chemerin and inflammatory factors with type 2 diabetes macroangiopathy and waist-to-stature ratio

Chemerin is an adipocytokine that participates in glycolipid metabolism; however, its association with type 2 diabetes (T2DM) with lower extremity macroangiopathy (T2DM-V) has rarely been reported. This study explored the association of chemerin and inflammatory factors with body fat parameters, glucolipid metabolism, and insulin resistance (IR) in T2DM and T2DM-V. Patients were classified into normal glucose regulation (NGR), T2DM, and T2DM-V groups. Serum chemerin, glucolipid metabolic parameters, transforming growth factor (TGF)-β, interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1 and fasting insulin levels were measured along with HOMA-IR, body mass index (BMI), and waist-to-stature ratio (WSR). Serum chemerin, TGF-β, IL-6 and MCP-1 levels were significantly higher in T2DM groups than in NGR group, and BMI, WSR, fasting plasma glucose (FPG), 2hPG, glycated hemoglobin (HbA1c), triglycerides (TG) and HOMA-IR were higher in T2DM-V subgroups with moderate or severe lower extremity macroangiopathy than in NGR group, simple T2DM group, and T2DM-V subgroup with mild macroangiopathy. FPG, 2hPG, HbA1c, TG and HOMA-IR were higher in T2DM-V subgroup with severe macroangiopathy than in T2DM-V with moderate macroangiopathy (p < 0.05). In all groups, serum chemerin levels were positively correlated with BMI, WSR, FPG, 2hPG, HbA1c, fasting insulin, aspartate transaminase, TG, TGF-β, IL-6 and HOMA-IR (p < 0.05) and negatively correlated with high-density lipoprotein cholesterol [HDL-c] (p < 0.05). Multiple stepwise regression analysis showed that 2hPG, HbA1c, and HDL-c were independent predictors of serum chemerin levels (β = -0.768, -0.122, -0.115, and 3.261, respectively; p < 0.01). Collectively, chemerin, factors associated with obesity, pathological and physiological changes in glucolipid metabolism, and inflammatory factors may promote the development of T2DM macroangiopathy

A deep learning–based method for improving reliability of multicenter diffusion kurtosis imaging with varied acquisition protocols

Multicenter magnetic resonance imaging is gaining more popularity in large-sample projects. Since both varying hardware and software across different centers cause unavoidable data heterogeneity across centers, its impact on reliability in study outcomes has also drawn much attention recently. One fundamental issue arises in how to derive model parameters reliably from image data of varying quality. This issue is even more challenging for advanced diffusion methods such as diffusion kurtosis imaging (DKI). Recently, deep learning–based methods have been demonstrated with their potential for robust and efficient computation of diffusion-derived measures. Inspired by these approaches, the current study specifically designed a framework based on a three-dimensional hierarchical convolutional neural network, to jointly reconstruct and harmonize DKI measures from multicenter acquisition to reformulate these to a state-of-the-art hardware using data from traveling subjects. The results from the harmonized data acquired with different protocols show that: 1) the inter-scanner variation of DKI measures within white matter was reduced by 51.5% in mean kurtosis, 65.9% in axial kurtosis, 53.7% in radial kurtosis, and 61.5% in kurtosis fractional anisotropy, respectively; 2) data reliability of each single scanner was enhanced and brought to the level of the reference scanner; and 3) the harmonization network was able to reconstruct reliable DKI values from high data variability. Overall the results demonstrate the feasibility of the proposed deep learning–based method for DKI harmonization and help to simplify the protocol setup procedure for multicenter scanners with different hardware and software configurations

SCRaMbLE generates designed combinatorial stochastic diversity in synthetic chromosomes

Synthetic chromosome rearrangement and modification by loxP-mediated evolution (SCRaMbLE) generates combinatorial genomic diversity through rearrangements at designed recombinase sites. We applied SCRaMbLE to yeast synthetic chromosome arm synIXR (43 recombinase sites) and then used a computational pipeline to infer or unscramble the sequence of recombinations that created the observed genomes. Deep sequencing of 64 synIXR SCRaMbLE strains revealed 156 deletions, 89 inversions, 94 duplications, and 55 additional complex rearrangements; several duplications are consistent with a double rolling circle mechanism. Every SCRaMbLE strain was unique, validating the capability of SCRaMbLE to explore a diverse space of genomes. Rearrangements occurred exclusively at designed loxPsym sites, with no significant evidence for ectopic rearrangements or mutations involving synthetic regions, the 99% nonsynthetic nuclear genome, or the mitochondrial genome. Deletion frequencies identified genes required for viability or fast growth. Replacement of 3′ UTR by non-UTR sequence had surprisingly little effect on fitness. SCRaMbLE generates genome diversity in designated regions, reveals fitness constraints, and should scale to simultaneous evolution of multiple synthetic chromosomes.</jats:p

Deep functional analysis of synII, a 770-kilobase synthetic yeast chromosome

INTRODUCTION Although much effort has been devoted to studying yeast in the past few decades, our understanding of this model organism is still limited. Rapidly developing DNA synthesis techniques have made a “build-to-understand” approach feasible to reengineer on the genome scale. Here, we report on the completion of a 770-kilobase synthetic yeast chromosome II (synII). SynII was characterized using extensive Trans-Omics tests. Despite considerable sequence alterations, synII is virtually indistinguishable from wild type. However, an up-regulation of translational machinery was observed and can be reversed by restoring the transfer RNA (tRNA) gene copy number. RATIONALE Following the “design-build-test-debug” working loop, synII was successfully designed and constructed in vivo. Extensive Trans-Omics tests were conducted, including phenomics, transcriptomics, proteomics, metabolomics, chromosome segregation, and replication analyses. By both complementation assays and SCRaMbLE (synthetic chromosome rearrangement and modification by loxP -mediated evolution), we targeted and debugged the origin of a growth defect at 37°C in glycerol medium. RESULTS To efficiently construct megabase-long chromosomes, we developed an I- Sce I–mediated strategy, which enables parallel integration of synthetic chromosome arms and reduced the overall integration time by 50% for synII. An I- Sce I site is introduced for generating a double-strand break to promote targeted homologous recombination during mitotic growth. Despite hundreds of modifications introduced, there are still regions sharing substantial sequence similarity that might lead to undesirable meiotic recombinations when intercrossing the two semisynthetic chromosome arm strains. Induction of the I- Sce I–mediated double-strand break is otherwise lethal and thus introduced a strong selective pressure for targeted homologous recombination. Since our strategy is designed to generate a markerless synII and leave the URA3 marker on the wild-type chromosome, we observed a tenfold increase in URA3 -deficient colonies upon I- Sce I induction, meaning that our strategy can greatly bias the crossover events toward the designated regions. By incorporating comprehensive phenotyping approaches at multiple levels, we demonstrated that synII was capable of powering the growth of yeast indistinguishably from wild-type cells (see the figure), showing highly consistent biological processes comparable to the native strain. Meanwhile, we also noticed modest but potentially significant up-regulation of the translational machinery. The main alteration underlying this change in expression is the deletion of 13 tRNA genes. A growth defect was observed in one very specific condition—high temperature (37°C) in medium with glycerol as a carbon source—where colony size was reduced significantly. We targeted and debugged this defect by two distinct approaches. The first approach involved phenotype screening of all intermediate strains followed by a complementation assay with wild-type sequences in the synthetic strain. By doing so, we identified a modification resulting from PCRTag recoding in TSC10 , which is involved in regulation of the yeast high-osmolarity glycerol (HOG) response pathway. After replacement with wild-type TSC10 , the defect was greatly mitigated. The other approach, debugging by SCRaMbLE, showed rearrangements in regions containing HOG regulation genes. Both approaches indicated that the defect is related to HOG response dysregulation. Thus, the phenotypic defect can be pinpointed and debugged through multiple alternative routes in the complex cellular interactome network. CONCLUSION We have demonstrated that synII segregates, replicates, and functions in a highly similar fashion compared with its wild-type counterpart. Furthermore, we believe that the iterative “design-build-test-debug” cycle methodology, established here, will facilitate progression of the Sc2.0 project in the face of the increasing synthetic genome complexity. SynII characterization. ( A ) Cell cycle comparison between synII and BY4741 revealed by the percentage of cells with separated CEN2-GFP dots, metaphase spindles, and anaphase spindles. ( B ) Replication profiling of synII (red) and BY4741 (black) expressed as relative copy number by deep sequencing. ( C ) RNA sequencing analysis revealed that the significant up-regulation of translational machinery in synII is induced by the deletion of tRNA genes in synII. </jats:sec

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected