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Direct finite element analysis of continuous spot welding was implemented with reverse geometric models of the actual stamping parts that comprise the back-side panel. This reverse panel showed apparent gaps after assembly and yielded to the electrodes and fixtures during welding, causing significant deformations. We acquired the total residual deformation in continuous simulation through a 3-D comparison between the original panel and the final deformed panel. This total deformation indicates that the deformations in the two processes offset with each other. We also performed a spot welding experiment and measured the actual residual deformation to validate the total deformation in simulation. They show good agreement in terms of deformation trend and magnitude. Finally, we designed seven comparative simulations to investigate the influence of the clamping pressure, electrode force, and spot welding sequence on the residual deformation. The results show that the sole increase of clamping pressure causes a deformation reduction in plate P4, while that of electrode force causes a deformation increase in P3. When the welding sequences of processes 1 and 2 are both reversed, the plate with the lowest deformation changes from P4 to P3. The final deformations in parts with multiple processes and multiple spot welds result from nonlinear interaction among many factors. The influence of a single factor change on the final deformation will be balanced by the remaining factors. This is why the fluctuations in total deformation are not significant between the standard simulation and each of the seven comparative simulations. The value of this article lies in the parameters optimization of spot welding based on reverse engineering and direct finite element analysis.

Direct finite element analysis that takes stamping dimensional deviations into account was achieved based on coupled electro-thermo-mechanical method and reverse engineering in the current research. The two continuous resistance spot welding processes of the reverse established back side panel were simulated. Its residual stresses and deformation were compared with those of the ideal back side panel. Large distortion presents in the reverse back side panel while only slight deformation exists in the ideal one. The former is validated to be closer to the deformation of the actual welded back side panel. The peak residual stresses after processes 1 and 2 remain almost unchanged in the reverse back side panel while those in the ideal one show an increasing trend. The final residual stresses of the reverse and the ideal back side panel are both high but the former is lower than the later. The stamping dimensional deviations are responsible for these differences. They lead to obvious attenuation of geometric features and large assembly clearances in the reverse back side panel. These assembly clearances allow large deformations of the stamping parts during the welding process. Meanwhile, these clearances make it relatively freer for the heated sheet metal to expand thermally in the thickness direction, resulting in less or even no residual stress in this direction. These clearances also promote the release of the thickness-direction component of the tensile residual stress in the extension direction of sheet by allowing deformation in the thickness direction.

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Activation of the nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome has been reported in diabetic kidney, yet the potential role of NLRP3 inflammasome in DN is not well known. In this study, we explored the role of NLRP3 inflammasome on inflammation and fibrosis in diabetic kidney using NLRP3 knockout mice. Renal expression of NLRP3, caspase-1 p10, interleukin-18 (IL-18) and cleaved IL-1β was increased in diabetic wild-type (WT) mice at 24 weeks. NLRP3 knockout (KO) improved renal function, attenuated glomerular hypertrophy, glomerulosclerosis, mesangial expansion, interstitial fibrosis, inflammation and expression of TGF-β1 and connective tissue growth factor (CTGF), as well as the activation of Smad3 in kidneys of STZ-induced diabetic mice. In addition, NLRP3 KO inhibited expression of thioredoxin-interacting protein (TXNIP) and NADPH oxidase 4 (Nox4) and superoxide production in diabetic kidneys. The diabetes-induced increase in urinary level of 8-hydroxydeoxyguanosine (8-OHdG) was attenuated in NLRP3 KO mice. In vitro experiments, using HK-2 cells, revealed that high glucose (HG)-mediated expression of TXNIP and Nox4 was inhibited by transfection with NLRP3 shRNA plasmid or antioxidant tempol treatment. Silencing of the NLRP3 resulted in reduced generation of reactive oxygen species (ROS) in HK-2 cells under HG conditions. Furthermore, we also found exposure of IL-1β to HK-2 cells induced ROS generation and expression of TXNIP and Nox4. Taken together, inhibition of NLRP3 inflammasome activation inhibits renal inflammation and fibrosis at least in part via suppression of oxidative stress in diabetic nephropathy.

Drought events show a continuous spatiotemporal structure. The evolution of drought and its probabilistic modeling from a three-dimensional perspective are important for drought mitigation and risk management. This study therefore aimed to extract hydrological drought variables using a three-dimensional identification method in the Upstream of Heihe River Basin (UHHRB) in Northwest China during 1961–2014. Then, the spatiotemporal dynamic evolution of hydrological drought event was quantified, and drought frequency was evaluated using copula functions. Results showed that the spatiotemporal structure of drought can be satisfactorily reflected using the three-dimensional framework. The most severe drought originated in the middle part of the basin, and propagated towards the eastern part with variable migration velocity. The Gumbel copula was the most suitable model for determining the joint distribution of drought duration, severity, and area. The conditional probability of drought variables with a given conditional factors decreases as the values of factor increase, and the increasing trend had no significant effect on reducing the probability of drought occurrence for a relatively higher value of drought variable. Drought risks would be underestimated (or overestimated) if simply the ‘and’ (or ‘or’) case return periods were considered. Drought frequency analysis considering the spatiotemporal drought features can be regarded as a reliable method. This study could help to better understand the spatiotemporal dynamic evolution of drought and to facilitate water resources allocation and drought mitigation.

Abnormal lipid metabolism contributes to the renal lipid accumulation, which is associated with diabetic kidney disease, but its precise mechanism remains unclear. The growing evidence demonstrates that thioredoxin-interacting protein is involved in regulating cellular glucose and lipid metabolism. Here, we investigated the effects of thioredoxin-interacting protein on lipid accumulation in diabetic kidney disease. In contrast to the diabetic wild-type mice, the physical and biochemical parameters were improved in the diabetic thioredoxin-interacting protein knockout mice. The increased renal lipid accumulation, expression of acetyl-CoA carboxylase, fatty acid synthase and sterol regulatory element binding protein-1, and phosphorylated Akt and mTOR associated with diabetes in wild-type mice was attenuated in diabetic thioredoxin-interacting protein knockout mice. Furthermore, thioredoxin-interacting protein knockout significantly increased the expression of peroxisome proliferator-activated receptor-α, acyl-coenzyme A oxidase 1 and carnitine palmitoyltransferaser 1 in diabetic kidneys. In vitro experiments, using HK-2 cells, revealed that knockdown of thioredoxin-interacting protein inhibited high glucose-mediated lipid accumulation, expression of acetyl-CoA carboxylase, fatty acid synthase and sterol regulatory element binding protein-1, as well as activation of Akt and mTOR. Moreover, knockdown of thioredoxin-interacting protein reversed high glucose-induced reduction of peroxisome proliferator-activated receptor-α, acyl-coenzyme A oxidase 1 and carnitine palmitoyltransferaser 1 expression in HK-2 cells. Importantly, blockade of Akt/mTOR signaling pathway with LY294002, a specific PI3K inhibitor, replicated these effects of thioredoxin-interacting protein silencing. Taken together, these data suggest that thioredoxin-interacting protein deficiency alleviates diabetic renal lipid accumulation through regulation of Akt/mTOR pathway, thioredoxin-interacting protein may be a potential therapeutic target for diabetic kidney disease.

Ti–24Nb–4Zr–7.9Sn alloy was prepared by Powder Metallurgy (PM) method using titanium hydride powder, niobium powder, zirconium powder, and tin powder as raw materials. The effect of sintering processing on microstructure, mechanical properties, and corrosion resistance was investigated in details. The alloy possessed dominant β-matrix and a little α-precipitation. The mechanical properties of the alloy sintered at 1250 °C for 2 h were better than those of the alloys with other sintering processing, which would avoid stress shielding and thus prevent bone resorption in orthopedic implants applications. As long-term stability in biological environment is required, the electrochemical behaviors in a simulated body fluid (Hank’s solution and simulated saliva solution) were also evaluated. Potentiodynamic polarization curves exhibited that the sample sintered at 1250 °C for 2 h had better corrosion properties than those of other sintering processing. The good corrosion resistance combined with better mechanical biocompatibility made the Ti–24Nb–4Zr–7.9Sn alloy suitable for use as orthopedic implants.

Two types of molybdate/silane composite films were obtained on the surface of hot-dip galvanized steel sheets by either directly immersing in a solution containing silane and molybdate as additive (single-step process), or firstly immersing in a molybdate solution, then in a silane solution (two-step process). The chemical compositions and microstructures of the films were examined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflection absorption infrared spectroscopy (RAIR). The corrosion resistances were investigated by electrochemical measurements and neutral salt spray (NSS) test. The results showed that the molybdate/silane composite film formed in the single-step process had a similar double-layer structure as that obtained in the two-step process. The inner layer was composed mainly of the elements O, Mo, Zn, and P, similar to the single molybdate film; whereas the outer layer was composed mainly of the elements C, O and Si, similar to the single silane film. Compared with the single molybdate or silane film, the corrosion current of the composite films was reduced and the impedance of the films was increased. Accordingly, the corrosion resistance of the composite films was remarkably enhanced to a level which was comparable to or even surpassing that of the conventional chromate passivation film.

MoSi2/WSi2 nanocrystalline powder has been successfully synthesized by the mechanical-assistant combustion synthesis method. This method includes a ball-milling process followed by combustion synthesis. The composition and microstructure of the as-milled powder mixture were detected by X-ray diffraction and scanning electron microscopy analyses. Their results show that the Mo(W) solid solution and Si nanocrystals could be obtained during the ball-milling process. Compared with normal powder mixture (Mo + Si + W), it could be easily ignited and high maximum combustion temperature was achieved. It was also confirmed that MoSi2/WSi2 solid solution powder with nanometric structure could be prepared through combustion synthesis method from the mechanical activated powder mixture.

SiC reinforced MoSi 2 composite powder with nanostructure has been successfully synthesized by mechanical-assistant combustion synthesis method. This process includes a ball-milling process followed by combustion synthesis. The composition and microstructure of as-milled powder mixture were detected by XRD and SEM analysis. Results showed that Mo and Si nanocrystallites could be obtained during the ball-milling process. Compared with normal powder mixture (Mo +Si + C), it could be easily ignited and higher maximum combustion temperature was achieved. Based on XRD and SEM, it was confirmed that MoSi 2 /SiC composite powder with nanometric structure could be prepared through combustion method from the mechanical activated powder mixture. At last, the as-synthesized powder was pressureless sintered. The relative density, flexural strength, Vicker's hardness and fracture toughness of the sintered samples are up to 99%, 468.7 MPa, 15.5 GPa and 9.35 MPa m 1/2 , respectively.