Tungsten combustion in impact initiated W-Al composite based on W(Al) super-saturated solid solution

Element W can effectively improve the density of energetic structural materials. However, W is an inert element and does not combust in air. To change the reaction characteristics of W, 60 at.% Al was introduced into W through mechanical alloying. XRD analysis shows that after 50 h of ball milling, the diffraction peak of Al completely disappears and W(Al60) super-saturated solid solution powder is obtained. Further observation by HAADF and HRTEM reveals that the W(Al60) super-saturated solid solution powder is a mixture of solid solution and amorphous phase. Based on the good thermal stability of W(Al60) alloy powder below 1000℃, W(Al60)-Al composite was synthesized by hot pressing process.Impact initiation experiments suggest that the W(Al60)-Al composite has excellent reaction characteristics, and multiple types of tungsten oxides are detected in the reaction products, showing that the modified W is combustible in air. Due to the combustion of tungsten, the energy release rate of the W(Al60)-Al composite at speed of 1362 m/s reaches 2.71 kJ/g.

Micromorphology and texture of niobium coating electrodeposited in NaCl−KCl−CsCl molten salt system

A low-toxicity and environment-friendly NaCl−KCl−CsCl−K_(2)NbF_(7) system was used to prepare Nb coatings on Mo substrates.The effects of temperature,current density and electrodeposition time on the micromorphologies and textures of the electrodeposited Nb coatings were studied.The results showed that Nb coatings obtained at 30−70 mA/cm^(2) in the temperature range of 700−750℃ were continuous and compact,with a hardness range of 2.16−2.45 GPa.As the columnar crystals grew with time,the preferential growth orientations of the Nb coatings changed from<200>to<211>and then became disordered.With increasing polarization,the morphologies of the Nb coatings changed from hexagonal star-like surface to conical or pyramid-like surface.

Subclinical hypothyroidism and the metabolic syndrome:A meta-analysis of cross-sectional studies

AIM： To determine the relationship between subclini-cal hypothyroidism （SCH） and the metabolic syndrome（MS）. METHODS： We performed a systematic search of da-tabases [MEDLINE （July 1950 to July 2012）, EMBASE（July 1966 to July 2012）] and the references of identi-fied studies. Completely published cross-sectional stud-ies of a general population involving SCH and the MSwere included. The pooled odds ratio and weightedmean difference （WMD） for the outcomes were calcu-lated using random-effects models.RESULTS： Six cross-sectional studies with 19546 partic-ipants were included. In total, 398 of 1324 participants（30.06%） in the SCH group had the MS compared with 4975 of 18222 participants （27.30%） in the euthyroid group [OR = 1.20; 95%CI： 1.05-1.36; P = 0.004; χ2 = 2.53 （P = 0.773）; I2 = 0%]. Further analysis of the components of the MS showed that SCH was associatedwith increased body mass index （WMD, 0.32 kg/m2; 95%CI： 0.04-0.61; P = 0.026）, systolic blood pressure （WMD, 2.62 mmHg; 95%CI： 1.35-3.89; P 〈 0.001） and triglyceride （WMD, 0.25 mmol/L; 95%CI： 0.23-0.28; P 〈 0.001）.CONCLUSION： Based on the cross-sectional data, SCH may be associated with an increased risk of the MS, which could be attributed to the increased risk of metabolic components.

Relationship between Neutrophil-to-Lymphocyte Ratio and Pulse Wave Velocity in Young Patients with Systemic Lupus Erythematosus

Background： The incidence of atherosclerosis-related myocardial infarction can be as much as 50-fold greater in young patients with systemic lupus e~,thematosus （SLE） than in age-matched controls. There are several explanations for this phenomenon, all of which result in a chronic state of low-grade inflammation. Recently, the neutrophil-to-lynlphocyte ratio （NLR） has been proposed as a useliil biomarker of inflammation. Pulse wave velocity （PWV） is a reliable indicator of vascular damage and atherosclerosis. There is a paucity of data concerning the relationship between NLR and atherosclerosis as measured by PWV in patients with SLE. This study aimed to verify whether there is a positive correlation between NLR and PWV and to explore factors that influence PWV in young SLE patients. Methods： A total of 90 female patients with SLE were enrolled in this cross-sectional investigation. Traditional and nontraditional cardiovascular risk factors were assessed on the same day that brachial-ankle PWV （baPWV） was examined. The patients were divided into three groups according to their mean baPWV values： patients whose mean baPWV value was lower than the first tertile were placed in Group 1 ： patients whose mean baPWV value was between the first tertile and the second tertile were placed in Group 2： and patients whose mean baPWV value was higher than the second tertile were placed in Group 3. SPSS 20.0 was used to perform all statistical analyses in this study. Both univariate linear regression and multivariate regression models were utilized to analyze the association between NLR and arterial stiffness. Results： Systolic blood pressure, diastolic blood presstire （DBP）. and triglycerides were all significantly different among Groups 1,2, and 3 （ 111.90 ± 12.85 mmHg vs. 114.60 ± 12.88 mmHg vs. 129.43 ±16.21 mmHg, P 〈 0.001 ： 68.77 ± 8.63 mmHg vs. 71.87 ± 9.77 mmHg vs. 82.57 ± 14.89 mmHg, P 〈 0.001 ; and 1.44 [0.91-2.47] mmol/L vs. 0.98 [0.78-1.26] mmol/L vs. 2.20 [0.94-3.66] mmol/L P = 0.030： respectively）, as were creatinine （57.50 [52.00-69.00] mmol/L vs. 55.50 [49.00-64.00] mmol/L vs. 64.00 [56.00-86.00] mmol/L P = 0.045） and blood urea nitrogen （4.27 [3.79-6.22] mmol/L vs. 4.16 [3.47-4.84] mmol/L vs. 5.88 [4.04-8.19] mmol/L, P = 0.011 ）. NLRs were significantly different among Groups 1, 2, and 3 （2.16 [1.56-3.42] vs. 3.12 [1.91-4.19] vs. 5.29 [2.63-7.25], P = 0.001）. N LR, together with DBP and the SLE disease activity index, independently predicts PWV. Conclusions： This study demonstrated that there was a positive correlation between NLR and PWV. Moreover, we found that disease activity and DBP were also positively correlated with PWV.

A comparative study of rhenium coatings prepared on graphite wafers by chemical vapor deposition and electrodeposition in molten salts

The purity,preferred orientation,microstructure,microhardness,bonding strength,thickness uniformity and thermal stability of rhenium(Re)coatings prepared on graphite wafers by chemical vapor deposition(CVD)and electrodeposition(ED)in molten salts were comparatively studied in this paper.It was found that carbon(0.0140 wt%)and oxygen(0.0067 wt%)were the primary impurities for CVD and ED Re coatings,respectively.The diffusion of carbon into CVD Re coating caused higher microhardness near the substrate and helped to improve the bonding strength at the same time.The preferred orientation,microstructure and microhardness of ED Re coating were all susceptible to oxygen.The coating deposition uniformity of ED Re is obviously better than that of CVD Re coating,due to its intrinsic characteristics.The(002)-oriented,coarse columnar CVD Re coating exhibited better thermal stability compared with that of the<110>-oriented,fiber-like columnar ED Re coating,while the ED Re grains grew remarkably and the microstructure evolved toward the similar structure of CVD Re after annealing treatment.The diversity of Re coatings in microstructure could be attributed to the mobility of grain boundaries(affected by temperature and impurity)during deposition processes.

Ablation-resistant Ir/Re coating on C/C composites at ultra-high temperatures

An iridium/rhenium(Ir/Re)double-layer coating was prepared on carbon/carbon(C/C)composites by chemical vapor deposition(CVD)and electrodeposition.The morphologies and bond strengths of the coatings on the C/C substrate were examined.The ablation resistance of the Ir/Re coating was studied at 1800℃in an oxyacetylene torch flame for 300 s.The results show that Re interlayer increases the bond strength between Ir coating and C/C substrate by over 100%.During entire hightemperature ablation process,Ir/Re coating keeps intact without any signs of ablation damage.Ir coating gets smoother and the grain size becomes larger after ablation,with the preferred orientation changing from h311i to h220i:Although some voids are observed along the grain boundaries of the as-ablated Ir coating,Ir/Re coating keeps intact on C/C composites.The study indicates that Ir/Re coating can provide good ablation resistance up to 1800℃for C/C composites,especially for the continuous ablation applications.