In this work, synthesis of copper/reduced graphene oxide composites to increase the electrical conductivity of copper matrix has been carried out. Pure copper particles were mixed with 0.28 wt%, ...1.1 wt% and 2.5 wt% graphene oxide (GO) contents. Different reduction methods were chosen to synthetize the Cu/rGO composite material: chemical reduction with hydrazine, thermal treatment at 815 °C in argon atmosphere. Characterization of the Cu/rGO composite disks was carried out by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Vickers Hardness and the electrical conductivity measured by Van der Pauw method of the Cu/rGO composites were analyzed. All the Cu/rGO disks showed lower hardness values than the Cu matrix. Microstructure of Cu/rGO composites is dominated by the presence of pores where GO agglomerates are accumulated and whose distribution and magnitude depends on the weight percentage of GO and the reduction process. Porosity percentage and pore size of Cu/rGO disks increase with GO content. Combination of chemical reduction with thermal treatment provides the most homogeneous microstructures with the smallest pore size and porosity percentage. Combination of both reduction treatments promotes more pathways for carrier transport within the reduced graphene oxide network structure, expanding areas of long-range conjugated structures and, consequently, increasing the electrical conductivity in the rGO/copper composites. Our research evidences that the Cu/rGO composites after chemical and thermal reduction increases the electrical conductivity, independently on the GO content, with respect to the pure copper matrix.
•Effective chemical-thermal reduction of graphene oxide in copper matrix is achieved.•C/O ratio of 6.9 in Cu/rGO composites after reduction treatments is obtained.•Increased electrical conductivity in Cu/rGO due to long-range sp2 structures.
The various (vitreous and crystalline) components of two type F fly ashes are quantified in this paper using three techniques: chemical analysis with selective solutions, X-ray powder diffraction ...combined with the Rietveld method and nuclear magnetic resonance. The findings confirm the suitability of the techniques to pursue the objectives while providing further insight into the chemical composition of the vitreous phase of the ash as well as an understanding of the thermal history of these materials. Finally, the paper corroborates the grounds established in prior research for regarding the glassy constituents of an ash to be instrumental in the control of its alkali reactivity during the manufacture of ‘alkaline cements’.
A combination of laboratory, histopathological and microbiological tests for diagnosis of prosthetic joint infection (PJI) have been strongly recommended. This study aims to characterize the accuracy ...of individual or group tests, such as culture of sonicate fluid, synovial fluid and peri-implant tissue, C-reactive protein (CRP) and histopathology for detection of early, delayed and late PJI.
A prospective study of patients undergoing hip or knee arthroplasty from February 2009 to February 2014 was performed in a Spanish tertiary health care hospital. The diagnostic accuracy of the different methods was evaluated constructing receiver-operating-characteristic (ROC) curve areas.
One hundred thirty consecutive patients were included: 18 (13.8%) early PJI, 35 (27%) delayed PJI and 77 (59.2%) late PJI. For individual parameters, the area under the ROC curve for peri-implant tissue culture was larger for early (0.917) than for delayed (0.829) and late PJI (0.778), p = 0.033. There was a significantly larger difference for ROC area in the synovial fluid culture for delayed (0.803) than for early (0.781) and late infections (0.679), p = 0.039. The comparison of the areas under the ROC curves for the two microbiological tests showed that sonicate fluid was significantly different from peri-implant tissue in delayed (0.951 vs 0.829, p = 0.005) and late PJI (0.901 vs 0.778, p = 0.000). The conjunction of preoperative parameters, synovial fluid culture and CRP, improved the accuracy for late PJI (p = 0.01). The conjunction of histopathology and sonicate fluid culture increased the area under ROC curve of sonication in early (0.917 vs 1.000); p = 0.06 and late cases (0.901 vs 0.999); p < 0.001.
For early PJI, sonicate fluid and peri-implant tissue cultures achieve the same best sensitivity. For delayed and late PJI, sonicate fluid culture is the most sensitive individual diagnostic method. By combining histopathology and peri-implant tissue, all early, 97% of delayed and 94.8% of late cases are diagnosed. The conjunction of histopathology and sonicate fluid culture yields a sensitivity of 100% for all types of infection.
Abstract Objective To determine the pregnancy outcome as a function of the first-trimester serum 25-hydroxyvitamin D3 25(OH)D status and to compare the 25(OH)D levels in the first and third ...trimesters. Methods Pregnant women (n = 466) tested for serum 25(OH)D levels during the first trimester were followed up until the end of pregnancy, and the obstetric and neonatal outcomes were compared in reference to the baseline 25(OH)D status. The third-trimester 25(OH)D levels were additionally measured in a subset of women (n = 148). Results The obstetric and neonatal outcomes did not vary as a function of the first-trimester 25(OH)D status. Neither did the 25(OH)D levels vary as a function of pregnancy outcomes. Overall, the 25(OH)D levels significantly decreased from the first to the third trimester. The first- and third-trimester 25(OH)D levels of samples initially taken during autumn/winter were significantly lower than those that were initially taken during spring/summer. Interestingly, the decrease in 25(OH)D levels during the third trimester was independent of the season of sampling. Conclusion The pregnancy outcome was independent of the first-trimester 25(OH)D status. Overall, the 25(OH)D levels significantly decreased in the third trimester. More research in this area is warranted.
Colorectal cancer (CRC) screening of the average risk population is only indicated according to age. We aim to elaborate a model to stratify the risk of CRC by incorporating environmental data and ...single nucleotide polymorphisms (SNP). The MCC-Spain case-control study included 1336 CRC cases and 2744 controls. Subjects were interviewed on lifestyle factors, family and medical history. Twenty-one CRC susceptibility SNPs were genotyped. The environmental risk model, which included alcohol consumption, obesity, physical activity, red meat and vegetable consumption, and nonsteroidal anti-inflammatory drug use, contributed to CRC with an average per factor OR of 1.36 (95% CI 1.27 to 1.45). Family history of CRC contributed an OR of 2.25 (95% CI 1.87 to 2.72), and each additional SNP contributed an OR of 1.07 (95% CI 1.04 to 1.10). The risk of subjects with more than 25 risk alleles (5
quintile) was 82% higher (OR 1.82, 95% CI 1.11 to 2.98) than subjects with less than 19 alleles (1
quintile). This risk model, with an AUROC curve of 0.63 (95% CI 0.60 to 0.66), could be useful to stratify individuals. Environmental factors had more weight than the genetic score, which should be considered to encourage patients to achieve a healthier lifestyle.
Background
Cytomegalovirus (CMV) is the most important viral pathogen in solid organ transplant (SOT) recipients. The role of secondary CMV prophylaxis in this population remains unclear.
Methods
...Retrospective cohort study in a single center. SOT recipients treated for CMV infection from 2007 to 2014 were studied to determine the efficacy and safety of secondary prophylaxis and its impact on graft loss and mortality. The outcome variable was CMV replication in the first 3 months after the end of therapy. Secondary variables were crude mortality and graft lost censored at 5 years after transplantation. Propensity score for the use of secondary prophylaxis was used to control selection bias.
Results
Of the 126 treated patients, 103 (83.1%) received CMV secondary prophylaxis. CMV relapse occurred in 44 (35.5%) patients. The use of secondary prophylaxis was not associated with fewer relapses (34.0% in patients with prophylaxis vs 42.9% in those without prophylaxis, P = .29). After a mean follow‐up of 32.1 months, graft loss was not different between both groups but patient mortality was significantly lower in patients who received secondary prophylaxis (5.8% vs 28.6%, P = .003).
Conclusion
Secondary prophylaxis did not prevent CMV infection relapse but it was associated with improved patient survival.
We document the presence of a Rhipicephalus microplus tick population resistant to acaricides (organophosphates (OP), synthetic pyrethroids (SP), amitraz) and macrocyclic lactones (ML) (ivermectin). ...Engorged females of R. microplus were collected from a cattle farm in Veracruz, Mexico, to evaluate acaricide and ivermectin resistance. The modified larval packet test (LPT) was used to detect OP (chlorpiriphos and diazinon) and SP (flumethrin, deltamethrin and cypermethrin) resistance and the larval immersion test (LIT) to detect resistance to amitraz and ivermectin. Both, LPT and LIT were performed twice at different times with different collected samples. Mortality data with ivermectin were subjected to probit analysis to obtain lethal concentrations and resistance ratios (RR) using an ivermectin-susceptible strain (Deutch) as a reference. The R. microplus population showed resistance to all acaricides tested, with different mortalities at the discriminate dose: chlorpiriphos (1%), diazinon (24.2%), flumethrin (92.8%), deltamethrin (94.2%), cypermethrin (98.0%) and amitraz (1.5%). The studied tick population also showed resistance to ivermectin with a resistance ratio at 99% of 9.58 and 6.52 in the first and second evaluation, respectively. We report for the first time a R. microplus population in Mexico with different levels of resistance to OP, SP, amidines (Am) and ivermectin. The uncontrolled use of these products in the study area may promote the complete failure of tick control within a short period of time.
We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGNs), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when ...multi-TeV gamma-rays from an AGN interact with extragalactic background light (EBL) photons to produce electron-positron pairs, which then interact with cosmic microwave background photons via inverse-Compton scattering to produce gamma-rays. Due to the deflection of the electron-positron pairs, a non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on the angular distribution of the cascade emission. In particular, an angular broadening compared to the unscattered emission could occur. Through non-detection of angularly broadened emission from 1ES 1218+304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around 10−14 G at the 95% confidence level. The extent of the exclusion range varies with the assumptions made about the intrinsic spectrum of 1ES 1218+304 and the EBL model used in the simulation of the cascade process. All of the sources are used to set limits on the flux due to extended emission.
The Kv7 subfamily of voltage-dependent potassium channels, distinct from other subfamilies by dint of its large intracellular COOH terminus, acts to regulate excitability in cardiac and neuronal ...tissues. KCNQ1 (Kv7.1), the founding subfamily member, encodes a channel subunit directly implicated in genetic disorders, such as the long QT syndrome, a cardiac pathology responsible for arrhythmias. We have used a recombinant protein preparation of the COOH terminus to probe the structure and function of this domain and its individual modules. The COOH-terminal proximal half associates with one calmodulin constitutively bound to each subunit where calmodulin is critical for proper folding of the whole intracellular domain. The distal half directs tetramerization, employing tandem coiled-coils. The first coiled-coil complex is dimeric and undergoes concentration-dependent self-association to form a dimer of dimers. The outer coiled-coil is parallel tetrameric, the details of which have been elucidated based on 2.0Å crystallographic data. Both coiled-coils act in a coordinate fashion to mediate the formation and stabilization of the tetrameric distal half. Functional studies, including characterization of structure-based and long QT mutants, prove the requirement for both modules and point to complex roles for these modules, including folding, assembly, trafficking, and regulation.
PDF
