Mode conversion of fundamental guided ultrasonic wave modes at part-thickness crack-like defects.

Guided ultrasonic waves can be employed for efficient structural health monitoring (SHM) and non-destructive evaluation (NDE), as they can propagate long distances along thin structures. The scattering (S0 mode) and mode conversion of low frequency guided waves (S0 to A0 and SH0 wave modes) at part-thickness crack-like defects was studied to quantify the defect detection sensitivity. Three-dimensional (3D) Finite Element (FE) modelling was used to predict the mode conversion and scattering of the fundamental guided wave modes. Experimentally, the S0 mode was excited by a piezoelectric (PZT) transducer in an aluminum plate. A laser vibrometer was used to measure the out-of-plane displacement to characterize the mode-converted A0 mode, employing baseline subtraction to achieve mode and pulse separation. Good agreement between FE model predictions and experimental results was obtained for perpendicular incidence of the S0 mode. The influence of defect depth and length on the scattering and mode conversion was studied and the sensitivity for part-thickness defects was quantified. The maximum mode conversion (S0-A0 mode) occurred for ¾ defect depth and the amplitude of the mode-converted A0 and scattered S0 modes mostly increased linearly as the defect length increased with an almost constant A0/S0 mode scattered amplitude ratio. Similar forward and backward scattering amplitude was found for the mode converted A0 mode. The mode conversion of the S0 to SH0 mode has the highest sensitivity for short defects, but the SH0 mode amplitude only increased slightly for longer defects. Employing the information contained in the mode-converted, scattered guided ultrasonic wave modes could improve the detection sensitivity and localization accuracy of SHM algorithms.

Guidelines for visualization and analysis of DC in tissues using multiparameter fluorescence microscopy imaging methods.

This article is part of the Dendritic Cell Guidelines article series, which provides a collection of state-of-the-art protocols for the preparation, phenotype analysis by flow cytometry, generation, fluorescence microscopy, and functional characterization of mouse and human dendritic cells (DC) from lymphoid organs and various non-lymphoid tissues. Here, we provide detailed procedures for a variety of multiparameter fluorescence microscopy imaging methods to explore the spatial organization of DC in tissues and to dissect how DC migrate, communicate, and mediate their multiple functional roles in immunity in a variety of tissue settings. The protocols presented here entail approaches to study DC dynamics and T cell cross-talk by intravital microscopy, large-scale visualization, identification, and quantitative analysis of DC subsets and their functions by multiparameter fluorescence microscopy of fixed tissue sections, and an approach to study DC interactions with tissue cells in a 3D cell culture model. While all protocols were written by experienced scientists who routinely use them in their work, this article was also peer-reviewed by leading experts and approved by all co-authors, making it an essential resource for basic and clinical DC immunologists.

Janus Ga2SSe nanotubes as efficient photocatalyst for overall water splitting.

Using sunlight to decompose water into hydrogen and oxygen is one of the most important ways to solve the current global environmental issues and energy problems. In this paper, we use density functional theory to predict the photocatalytic performance of Janus Ga2SSe nanotubes (JGSSe NTs) for the first time. The result shows that the small formation energy and strain energy ensure the stability of the nanotubes. Compared with monolayers, the visible light absorption range of JGSSe NTs is wider, and the large radius (>26.60 A) nanotubes all meet the hydrolysis potential. Surprisingly, the hole mobility of JGSSe NT was estimated to be as high as 2.89 × 104cm2V-1S-1. In conclusion, JGSSe nanotubes are expected to be an excellent photocatalyst due to their low electron-hole recombination rate, high hole mobility, solar absorption in the visible light range, and good oxidation capacity. In addition, the nanotube band gap can be effectively regulated by applying strain. It is hoped that our research will provide meaningful progress in the development of novel and efficient photocatalysts. We hope that our research will provide a possible way to develop novel and efficient photocatalysts.

Identification and expression analysis of xyloglucan endotransglucosylase/hydrolase (XTH) family in grapevine (Vitis vinifera L.).

Xyloglucan endotransglucosylases/hydrolases (XTH) are key enzymes in cell wall reformulation. They have the dual functions of catalyzing xyloglucan endotransglucosylase (XET) and xyloglucan endonuclease (XEH) activity and play a crucial role in the responses against abiotic stresses, such as drought, salinity, and freezing. However, a comprehensive analysis of the XTH family and its functions in grapevine (Vitis vinifera L.) has not yet been completed. In this study, 34 XTHs were identified in the whole grapevine genome and then named according to their distribution on chromosomes. Based on a phylogenetic analysis including Arabidopsis XTHs, the VvXTHs were classified into three groups. Cis-element analysis indicated that these family members are related to most abiotic stresses. We further selected 14 VvXTHs from different groups and then examined their transcription levels under drought and salt stress. The results indicated that the transcription levels of selected VvXTHs in the leaves and roots presented the largest changes, suggesting that VvXTHs are likely to take part in the responses to drought and salt stress in grapevines. These results provide useful evidence for the further investigation of VvXTHs function in response to abiotic stresses in grapevine.

Genome-wide analysis of the strigolactone biosynthetic and signaling genes in grapevine and their response to salt and drought stresses.

Strigolactones (SLs) are a novel class of plant hormones that play critical roles in regulating various developmental processes and stress tolerance. Although the SL biosynthetic and signaling genes were already determined in some plants such as Arabidopsis and rice, the information of SL-related genes in grapevine (Vitis vinifera L.) remains largely unknown. In this study, the SL-related genes were identified from the whole grapevine genome, and their expression patterns under salt and drought stresses were determined. The results indicated that the five genes that involved in the SL biosynthesis included one each of the D27, CCD7, CCD8, MAX1 and LBO genes, as well as the three genes that involved in the SL signaling included one each of the D14, MAX2, D53 genes. Phylogenetic analysis suggested that these SL-related proteins are highly conserved among different plant species. Promoter analysis showed that the prevalence of a variety of cis-acting elements associated with hormones and abiotic stress existed in the promoter regions of these SL-related genes. Furthermore, the transcription expression analysis demonstrated that most SL-related genes are involved in the salt and drought stresses response in grapevine. These findings provided valuable information for further investigation and functional analysis of SL biosynthetic and signaling genes in response to salt and drought stresses in grapevine.

Structural and electronic properties of double-walled G-C3N4 nanotubes: a density functional theory study.

In the present work, we investigated the geometric, electronic, and photocatalytic properties of g-C3N4single-walled nanotube (SWCNNTs) and g-C3N4double-walled nanotubes (DWCNNTs). The negative strain energy indicates that the SWCNNTs have a stable structure, while the most stable combination in the DWCNNT is (6, 0)@(12, 0). The energy band gaps of (n, 0) SWCNNTs increase while that of (n,n) SWCNNTs decrease as the diameter increase. Moreover, the calculated nanotubes have the ability of photocatalytic water splitting, and the valance band maximum of nanotubes are much lower than that of the monolayer, indicating that the nanotubes have better oxidation capacity than the monolayer. On the other hand, our calculations show that DWCNNTs have type II band alignment with a band gap width significantly smaller than that of SWCNNTs. Interestingly, DWCNNT exhibited a smaller effective mass of electrons than SWCNNTs, which is beneficial to electron migration. Therefore, the construction of nanotube is an effective way to improve the photocatalytic performance of g-C3N4monolayer materials.

A Generic Compliance Modeling Method for Two-Axis Elliptical-Arc-Filleted Flexure Hinges.

As a kind of important flexible joint, two-axis flexure hinges can realize in-plane and out-of-plane motions and can be used for constructing flexure-based spatial compliant mechanisms. The paper introduces a common two-axis elliptical-arc-filleted flexure hinge that is generated by two different elliptical-arc-filleted cutout profiles and that provides some new hinge types. The analytical compliance equations of both half-segments of the two-axis elliptical-arc flexure hinges are firstly formulated, and then, based on a generic compliance modeling method of a flexure serial chain, the closed-form compliance and precision matrices of two-axis elliptical-arc-filleted flexure hinges are established and validated by the finite element method. Some numerical simulations are conducted to compare the effect of different design geometric parameters on the performance of the two-axis flexure hinges.

[Roles of hMMS2 gene in reversing the oxaliplatin tolerance of human colon carcinoma cells].

In this study, the roles of hMMS2 (human methyl methanesulfonate sensitive mutant 2) gene encoding the human ubiquitin-conjugating enzyme E2 variant 2 in the drug resistance in human colon carcinoma were investigated by using a well-differentiated human colorectal carcinoma L-OHP-resistant cell line, THC8307/L-OHP. THC8307/L-OHP cells were transfected via liposome along with plasmid pcDNA6.2-GW/EmGFP-miR-MMS2 expressing both miRNA against hMMS2 and GFP, followed by real-time fluorescent quantitative PCR and immunofluorescence to select stable transfectants with significantly reduced hMMS2 expression. Compared with untransfected or pcDNA6.2-GW/EmGFP vector-transfected cells, the hMMS2-depleted cells displayed significantly (P<0.05) reduced half inhibition concentration(IC50) resistance index (RI) and colony-forming efficiency (CFE) upon treatment with oxaliplatin (L-OHP), while its relative reverse efficiency(RRE) was significantly higher (P<0.05) than the control cells, indicating compromised ability of cell proliferation. Indeed, Rho-damine 123 staining and flow cytometry analyses revealed an increased rate of apoptosis in hMMS2-depleted cells while no difference in cell proliferation or apoptosis was observed between the two control cell lines. The above observations collec-tively indicate that suppression of hMMS2 reverses L-OHP tolerance in differentiated human colorectal carcinoma cells by promoting apoptosis.

Implantable cardioverter defibrillator therapy in chronic kidney disease: a meta-analysis.

AIMS: Recent observational studies have shown that implantable cardioverter defibrillator (ICD) patients with chronic kidney disease (CKD) have increased mortality and therefore the value of device therapy in this group has been questioned. The purpose of this meta-analysis was to systematically analyse the effect of renal dysfunction on mortality of ICD patients. METHODS AND RESULTS: Pubmed, Cochrane clinical trials database, and EMBASE were searched until December 2008. In addition, a manual search was performed using review articles, reference lists of papers, and abstracts from conference reports. Of the 90 initially identified studies, 11 observational studies with 3010 patients were analysed. The meta-analysis of these studies showed that CKD was associated with higher mortality risk (HR = 3.44, 95% CI 2.82-4.21, Z = 12.09, P < 0.001) while there were no significant differences between individual trials (P = 0.09, I(2) = 37.8%). A subgroup analysis which included the four studies that used estimated glomerular filtration rate (GFR) <60 mL/min/1.73 m(2) to define CKD showed a higher mortality in the CKD group as well (HR = 3.06, 95% CI 2.31-4.04, Z = 7.84, P < 0.001) without significant heterogeneity (P = 0.38, I(2) = 5.2%). CONCLUSION: Our meta-analysis suggests that CKD is associated with increased mortality in patients who receive ICD therapy. Undoubtedly, prospective studies are needed in order to elucidate the impact of different stages of CKD in this setting. Given that the CKD prevalence is rapidly increasing, there is an imperative need for better risk stratification of ICD therapy candidates.

Meta-analysis of association between C-reactive protein and immediate success of electrical cardioversion in persistent atrial fibrillation.

Current evidence links atrial fibrillation (AF) to the inflammatory state. Also, increased C-reactive protein (CRP) levels have been associated with greater risk of recurrence of AF after successful electrical cardioversion (EC). We conducted a meta-analysis of observational studies to examine the association between baseline CRP levels and the immediate success of EC in persistent AF. We searched the literature published November 2007 or earlier. In addition, a manual search was performed using all review articles on this topic, reference lists of studies, and abstracts from conference reports. Of the 342 initially identified studies, 6 prospective observational studies with a combined 366 patients (297 with successful and 69 with failed EC) were analyzed. Overall, CRP levels were greater in patients with failed EC. The standardized mean difference in the CRP levels between patients with successful and those with failed EC was -0.41 units (95% confidence intervals -0.68 to -0.14) and the Z score for overall effect was 2.98 (p=0.003). The heterogeneity test showed that there were no significant differences between the individual studies (p=0.36; I(2)=9.1%). In conclusion, our meta-analysis suggests that increased CRP levels are associated with greater risk of EC failure. CRP assessment before cardioversion may provide prognostic information regarding the success of the procedure.

Statin use and development of atrial fibrillation: a systematic review and meta-analysis of randomized clinical trials and observational studies.

BACKGROUND: Inflammation and oxidative stress have been associated with atrial fibrillation (AF). On the other hand, accumulating evidence suggests that statins may have antiarrhythmic effects due to pleiotropic properties. However, inconsistent results have been reported with respect to AF. AIMS: We conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) and observational studies to examine the association between statin use and development of AF. METHODS: PubMed, Cochrane clinical trials database, and EMBASE were searched until November 2006. In addition, a manual search was performed using all review articles on this topic, reference lists of papers, and abstracts from conference reports. Of the 309 initially identified studies, 6 RCTs and 10 observational studies with 7041 patients were finally analyzed. RESULTS: The analysis of RCTs showed no significant effect of statins on AF development (RR=0.76, 95% CI:0.55-1.05, P=0.09), and significant heterogeneity between individual studies (P=0.0008, I(2)=74.0%). Subgroup analysis revealed that differences in AF detection methodology may be the cause of heterogeneity. The analysis of observational studies demonstrated that statin use reduced the relative risk for AF by 23% (95% CI:0.70-0.85, Z=4.95, P<0.00001) without significant differences between the trials (P=0.08, I(2)=41.2%). This favorable effect was greatest in the post-operative patients (RR=0.61, 95% CI:0.49-0.76, Z=4.30, P<0.0001). CONCLUSION: Our meta-analysis suggests that statins may be effective in AF prevention especially in the post-operative setting. However, there are insufficient data for the widespread use of statins solely for AF prevention. Larger RCTs with long-term follow-up in different clinical settings, and more sensitive methods of arrhythmia detection are needed to clarify the impact of statins on AF.

Association between C-reactive protein and recurrence of atrial fibrillation after successful electrical cardioversion: a meta-analysis.

OBJECTIVES: We conducted a systematic review and meta-analysis of observational studies to examine the association between baseline C-reactive protein (CRP) levels and the recurrence of atrial fibrillation (AF) after successful electrical cardioversion (EC). BACKGROUND: Current evidence links AF to the inflammatory state. Inflammatory indexes such as CRP have been related to the development and persistence of AF. However, inconsistent results have been published with regard to the role of CRP in predicting sinus rhythm maintenance after successful EC. METHODS: Using PubMed, the Cochrane clinical trials database, and EMBASE, we searched for literature published June 2006 or earlier. In addition, a manual search was performed using all review articles on this topic, reference lists of papers, and abstracts from conference reports. Of the 225 initially identified studies, 7 prospective observational studies with 420 patients (229 with and 191 without AF relapse) were finally analyzed. RESULTS: Overall, baseline CRP levels were greater in patients with AF recurrence. The standardized mean difference in the CRP levels between the patients with, and those without AF was 0.35 units (95% confidence interval 0.01 to 0.69); test for overall effect z-score = 2.00 (p = 0.05). The heterogeneity test showed that there were significant differences between individual studies (p = 0.02; I(2) = 60.2%). Further analysis revealed that differences between the CRP assays possibly account for this heterogeneity. CONCLUSIONS: Our meta-analysis suggests that increased CRP levels are associated with greater risk of AF recurrence, although there was significant heterogeneity across the studies. The use of CRP levels in predicting sinus rhythm maintenance appears promising but requires further study.