Search

The paper describes a high-current Gas Metal Arc Welding (GMAW) process using wire electrodes with diameters up to 4.0 mm for single-pass full penetration butt joint welding of 20 mm thick steel plates. Fundamental research aims to develop thick-wire GMAW into a high-efficiency method by identifying the limits of welding performance and achievable deposition rates. Current gaps in understanding include equipment requirements, process properties, application fields, and weld quality. The research project addresses these gaps through systematic investigations of basic technological analyses, application sample welding, and quality evaluations. The objective was to create a robust, cost-efficient gas-shielded high-performance welding technology with deposition rates comparable to Submerged Arc Welding. The fully mechanized, automatic welding setup included two parallel-connected welding power sources, one wire feeder and one high-power welding torch. Welding parameters and conditions were evaluated with the aim of achieving a high-quality weld. Optimal parameters were identified for one-sided single-pass welding on 20 mm thick plates. Validation of thick-wire GMAW for 20 mm thick high-strength steels was conducted via two-sided single-pass welding on S690Q grade plates. Testing of the weld joint included static tensile strength test (3x tensile specimen), a Charpy impact test at −40 °C (6x Charpy V-notch specimens respectively with notch position in weld metal, base material and heat-affected zone (HAZ)), microstructure examination and a hardness test. The lowest recorded impact energy was observed to be 50 J within the weld metal, in combination with hardness peaks in the HAZ reaching 415 HV1, and all tensile specimens failing outside the HAZ within the base material. The process achieved reliable, reproducible, and economical joint welding, meeting necessary mechanical-technological quality standards. The paper enhances the understanding of selected welding techniques tor thick plate joining and offers valuable industrial insights, demonstrating the technique's applicability and feasibility for high-strength applications. [ABSTRACT FROM AUTHOR]

Background: Studies have shown that staff who support adults with intellectual disabilities (ID) are exposed to challenging behaviour in their work including client aggression. Exposure to aggressive behaviour has been associated with staff stress and burnout. Study samples have been small however, and there has been very little data exploring this issue among North American staff. Methods: A cross-sectional survey which included demographics, measures of frequency and severity (including perceived severity and a standardised severity score) of exposure to client aggression and the Maslach Burnout Inventory-Human Services Survey (MBI-HSS) was completed by 926 community staff who support adults with ID in Ontario, Canada. Relationships between demographic variables and exposure to aggression were examined with descriptive statistics. Pearson correlations were used to analyse exposure variables and MBI-HSS scores. Results: Nearly all staff reported being exposed to client aggression in the prior 6 months. Mean MBI-HSS scores were comparable to previously published data in similar populations with the exception of a higher score in the personal accomplishment domain. All measures of exposure to aggression were significantly positively correlated with MBI-HSS scores in the emotional exhaustion and depersonalisation dimensions of burnout. Conclusions: The prevalence of burnout in this North American sample is comparable to what has been reported in similar populations in other locations, although these staff may have a higher sense of accomplishment with regard to their work. Findings from this large sample support the evidence that exposure to client aggression affects staff emotional well-being but is by no means the only important factor. Further study is needed to explore the differences and similarities reported here as well as other contributing factors which will guide the implementation of effective strategies to improve staff well-being. (Contains 2 tables.)

Summary: Background: Surgical site infections (SSIs) after median sternotomy represent a serious complication and a high potential risk for adverse clinical outcome after cardiac surgery. The antimicrobial skin sealant InteguSeal® was introduced as a novel tool in preventing development of SSI. Aim: This single-centre investigation used two prospective registries to evaluate the prophylactic effect of a cyanoacrylate-based antimicrobial skin sealant (InteguSeal®) on the incidence of postoperative mediastinitis or any other form of chest skin incision SSI after elective cardiac surgery. Methods: Between October 2010 and April 2011 a total of 998 patients underwent elective cardiac surgical procedures with median sternotomy in our centre. In 496 patients InteguSeal® was included in standard preoperative preparation procedures before chest skin incision (group 1). In 502 patients standard preoperative skin preparation procedures were used without InteguSeal® (group 2). Freedom from mediastinitis and from any other form of SSI within 30 postoperative days were the primary and secondary endpoints, respectively. Findings: A total of 983 patients were eligible for inclusion in per-protocol analysis (488 vs 495 patients). The incidence of postoperative mediastinitis was 2.3% in group 1 vs 3.2% in group 2 (not significant). The incidence of any form of SSI was 10.9% in group 1 vs 11.5% in group 2 (not significant). Perioperative patient characteristics, complexity of surgical procedures performed and length of hospitalization were similar in both groups. Conclusion: The use of InteguSeal® has no influence on the incidence of postoperative SSI and mediastinitis after cardiac surgery with median sternotomy. [Copyright &y& Elsevier]

Abstract: Achieving uniform flow among the cells of a fuel cell stack plays a significant role in being able to operate at maximum capability and efficiency. This paper presents experimental data showing the importance of cell-to-cell fuel flow balancing on fuel cell performance, and a fuel cell energy management (FCEM) technique that has demonstrated the ability to improve stack performance. In a specially instrumented four-cell polymer electrolyte fuel cell that allows external control of the air, fuel, and water-cooling flows to each cell, fuel to a single cell was reduced. V–I curves collected under these unbalanced conditions are compared to curves collected when the fuel flow to each cell was balanced. Reducing the fuel flow to a single cell by 11% decreased the V–I curve cutoff load by 10%—demonstrating the degree of negative effect that unbalanced fuel flows can have on stack performance. Typical fuel cell stacks have no dynamic means to keep flows in the stack balanced between the cells, but through the use of custom-built, piezoelectric micro-valves, a simple flow control strategy, and this custom four-cell laboratory stack, the positive effects of FCEM flow balancing at three different fuel flow rates was demonstrated. [Copyright &y& Elsevier]

In order to acquire real-time transient alkali data on coal-derived gaseous fuel and combustion streams often at low ppb levels, an extractive, total (vapor and particle-bound) sodium and potassium monitor has been designed, constructed, and tested. This fiber-optic alkali monitor (FOAM) utilizes state-of-the-art fiber-optic light transfer, a novel light-filtering background correction method, and high sensitivity photodiode signal detection. The sample enters the monitor’s high-temperature flame, which supplies energy to both decompose and excite the sample. The flame then emits light at the characteristic wavelengths of sodium and potassium. The resulting emissions are transferred by the fiber-optic bundle to the detection system, where the signal is filtered, background corrected, and transferred to the data system. The FOAM has advantages over previous instrumentation in being rugged, portable, and compact. Laboratory testing of the FOAM has been completed. The FOAM was determined to be highly sensitive (mid-ppt detection limits) with a wide linear dynamic range (four orders of magnitude). The results of field monitoring of alkali levels in the exhaust stream of a pressurized combustor using the FOAM indicated that the monitor was capable of real-time, fast tracking of transient alkali behavior in a high-temperature/high-pressure process stream. [ABSTRACT FROM AUTHOR]

This study was conducted to compare the effects of 60-day dietary exposure (2%) to low melt point paraffin wax (LMPW) on both general liver morphology and Kupffer cell (KC) function and morphology in female F-344 and Sprague-Dawley (SD) rats. Livers from only F-344 rats fed LMPW had granuloma formation/lymphoid cell aggregates with small areas of necrosis. Significant increases in serum alanine and aspartate aminotransferase as well as γ-glutamyltransferase activities were detected only in treated F-344 rats. Additionally, detectable amounts of LMPW were present only in livers of treated F-344 rats. Because KC can be involved in granuloma formation, their morphology and function were examined. Electron microscopy revealed the presence of large, irregularly shaped, membrane-associated vacuoles in cells isolated from F-344 rats exposed to LMPW. These vacuoles were not seen in KC from control rats and rarely detected in KC isolated from LMPW-exposed SD rats. Moreover, indices of KC function including phagocytic activity and nitric oxide and superoxide anion production were significantly increased by KC isolated from F-344 rats exposed to LMPW (1.6-, 36-, and 2.2-fold increases, respectively) over untreated controls. In contrast, LPS-stimulated production of TNF and LTB4 was significantly decreased only in KC of LMPW-fed F-344 rats. No significant changes in these functions were observed in KC isolated from SD rats exposed to LMPW or from KC isolated from control F-344 or SD rats. These data provide evidence that dietary LMPW alters the morphology and functional capacity of KC of F-344 but not SD rats and these changes may ultimately lead to granuloma formation. [ABSTRACT FROM PUBLISHER]

The converse piezoelectric response of aluminum nitride evaluated using standard metal insulator semiconductor structures has been found to exhibit a linear dependence on the work function of the metal used as the top electrode. The apparent d33 of the 150–1100 nm films also depends on the dc bias applied to the samples. [ABSTRACT FROM AUTHOR]

A two-current path model is presented to describe the operation of the Si/CoSi2/Si epitaxial, heterostructure transistor. The model gives a good account of the device behavior and allows us to conclude that it works by activated charge control, in a formal sense like a bipolar transistor. The analysis further suggests that with the fine base dimensions made possible by the single crystal, vertical structure one can foresee devices with β’s of a 100 or more, at the same time maintaining a transconductance close to the optimal value 0.04 mhos/mA characteristic of a charge injection device. [ABSTRACT FROM AUTHOR]

We report transistor action in a Si/CoSi[sub 2]/Si structure. The thin silicide layer (<100 Å), which acts as the base, is a single-crystal metal, essentially continuous and locally exhibiting atomically perfect interfaces with Si. The transistor action is manifested by a common base current gain a as high as 0.6 and a voltage gain greater than 10. [ABSTRACT FROM AUTHOR]

Transport studies have been performed on thin films of CoSi2 and NiSi2 in the temperature range 1-300 K. The conductivities are metallic with essentially the same temperature dependence; however, the residual resistivities are markedly different even though the two silicides are structurally similar (the room-temperature resistivity of NiSi2 being at least twice that of CoSi2 of 15 μΩ cm). The difference is attributed to intrinsic defects in NiSi2. This defect has been simulated by ion bombardment of the film where it is also shown that Matthiessen's rule is obeyed over a remarkable range of bombardment doses. [ABSTRACT FROM AUTHOR]

The formation of TiSi2 thin films on Si has been investigated by in situ x-ray diffraction and electrical transport. The x-ray results show unequivocally that the staging proceeds through two orthorhombic polytypes of TiSi2 according to the sequence: sputter-deposited metallic Ti or TiSix alloy films on Si(001)→TiSi2 (C49 structure)→TiSi2 (C54 structure), with no evidence of lower silicides. Electrical transport shows metallic behavior for all phases and distinctive features in the annealing curves which correlate with the structural transformations. Most important, the resistivity, characteristically very high for the C49 phase, undergoes a precipitous drop at the C49→C54 transition. In the C54 phase when fully annealed the resistivity is 12.4 μΩ cm at room temperature and 0.66 μΩ cm at 4.2 K. [ABSTRACT FROM AUTHOR]

We report the fabrication of epitaxial CoSi2 layers on Si(111) as thin as 1 nm. The crystalline lattice of these layers is coherent with the Si lattice, and the silicide is electrically continuous. There are pronounced structural differences between films which are less than 3 nm thick and those which are thicker. The resistivity of the layers increases sharply with decreasing thickness. This is the first report of the growth of coherent, electrically continuous CoSi2 layers on Si. [ABSTRACT FROM AUTHOR]

Objectives: Engineered Heart Tissue (EHT) can be used to investigate cardiomyocyte hypertrophy in vitro. In this model coherently beating rat cardiomyocytes in 3D tissue culture are acutely forced to work against an increased afterload. They subsequently display hypertrophy and functional and transcriptional alterations stereotypically associated with heart failure. In the present study we used the model to investigate DNA methylation patterns of cardiomyocyte hypertrophy. We assessed two different approaches: An unbiased microarray and bisulfite sequencing of promoter regions of genes associated with pathological hypertrophy.Methods: EHTs were cultured on hollow silicone posts in a 24-well format for 2 weeks until maturation. Afterload was then acutely increased (“afterload enhanced”, AE) by inserting metal braces into the hollow silicone posts for one week. Additional EHTs were treated with phenylephrine to induce hypertrophy (PE), control EHTs were left untreated. Methylated DNA fragments were enriched by MBD2 pull-down and quantified by microarray. Data was evaluated and mapped using DEVA, R and DAVID software. Additionally, DNA from EHTs was sodium bisulfite treated to convert all non-methylated cytosines to thymidines. Promoter region fragments of Nppa, Nppb, Acta-1 and Atp2a2 (ANP, BNP, alpha skeletal muscle actin and Serca2a) and methylation positive and negativ controls Oxt and Ube2b were PCR amplified and subjected to next generation sequencing (NGS). Single-base resolution methylation data was extracted by Bismark software.Results: In the microarray analysis PE and AE clustered together. Methylation changes among AE or PE and controls respectively mapped to pathways relevant for pathological hypertrophy. Further analyses identified previously unidentified differentially methylated regions and confirmed differential methylation in well-studied genes such as Serca2a, supporting the validity of the approach. Targeted NGS confirmed subtle but reproducible DNA methylation alterations in promoter regions of hypertrophy associated genes. A region at -3000 bp of the Serca2a transcriptional start site was identified as differentially methylated using the microarray approach and confirmed by NGS.Conclusion: Exposing EHTs to enhanced afterload rapidly and specifically alters DNA methylation in cardiac myocytes. In vitro hypertrophy is accompanied by a common DNA methylation signature irrespective of the cause of hypertrophy. Its probable regulatory function and high plasticity suggest DNA methylation as a possible drug target in cardiac hypertrophy. [ABSTRACT FROM AUTHOR]

Presents the poem "Noah's Wife Dreams," by J. Ivan Hensel. First Line: Curled under my arm, Last Line: soon the world will be ours...