Abnormal expression of TBX4 during anorectal development in rat embryos with ethylenethiourea-induced anorectal malformations

Abstract Background To assess the expression of T-box transcription factor 4 (TBX4) during the anorectal development in normal and ethylenethiourea (ETU)-induced anorectal malformations (ARM) rat embryos. Methods Anorectal malformations was induced by ETU on the 10th gestational day (E10) in rat embryos. Spatio-temporal expression of TBX4 was evaluated in normal (n = 490) and ETU-induced ARM rat embryos (n = 455) from E13 to E16 by immunohistochemical staining, Western blot analysis and real-time RT-PCR. Results In the normal embryos, immunohistochemical staining revealed that TBX4 expression was detected in the epithelium of hindgut and urorectal septum (URS) on E13. TBX4-immunopositive cells were increased significantly in the epithelium of hindgut and URS, the future anal orifice part of cloacal membrane on E14. On E15, abundant stained cells were observed in the rectum, URS and dorsal cloacal membrane and the expression of positive cells reached its peak. On E16, only sporadic positive cells were distributed in the epithelium of the distal rectum. In the ARM embryos, the hindgut/rectum, URS and dorsal cloacal membrane were faint for TBX4 immunohistochemical staining. In the normal group, TBX4 protein and mRNA expression showed time-dependent changes in the hindgut/rectum from E13 to E16 on Western blot and real-time RT-PCR. On E13 and E15, the expression level of TBX4 mRNA in the ARM group was significantly lower than that in the normal group (P < 0.05). On E15, the expression level of TBX4 protein in the ARM group was significantly lower than that in the normal group (P < 0.05). Conclusions The expression of TBX4 was downregulated in ETU-induced ARM embryos, which may play important roles in the pathogenesis of anorectal development

Porous Ni-Cr-Mo-Cu alloys fabricated by elemental powder reactive synthesis

Fabrication of porous Ni-Cr-Mo-Cu alloys is available through Ni, Cr, Mo and Cu elemental powder reactive synthesis at the sintering temperature of 1150 °C. The pore structures, including swelling behavior, open porosity, pore size and viscous permeability of the porous Ni-Cr-Mo-Cu alloys are systematically investigated. The results revealed that the parameters of pore structure firstly increased, and then decreased with the increase of the sintering temperature. When the sintering temperature rose to 1000 °C, the volume expansion, open porosity and viscous permeability of porous Ni-Cr-Mo-Cu alloys reached the peak value of 8.0%, 41.6% and 17.2 μ m ^2 , respectively. In addition, it was confirmed that the pore structure evolution was based on three stages, that is, in the low temperature section before stearic acid decomposition, the formation of pores was initiated by the volatilization of pore-forming agent and the interstitial pores of green compact; when the temperature was lower than 1083 °C, the increase of open porosity was mainly due to the Kirkendall effect caused by solid partial diffusion; while, when the temperature is within the range of 1083 ∼ 1150 °C, the shrinkage behavior at high temperature and a small amount of metal solution formed by the unreacted Cu led to decrease in pore structure parameters

Effects of Cr content on the corrosion behavior of porous Ni–Cr–Mo–Cu alloys in H3PO4 solution

Porous Ni–Cr–Mo–Cu alloys were prepared via reaction synthesis of mixed powders. Electrochemical performance test and weight-loss method were used to evaluate the effects of chromium content in the range of 10 ∼ 30 wt% on the alloys corrosion performance in 30 wt% H _3 PO _4 solution. The microstructure, element valence and phase composition of the porous Ni–Cr–Mo–Cu alloys were characterized via scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and x-ray diffraction analysis (XRD), respectively. And the results show that the alloys exhibited serviceable corrosion performance and the corrosion behavior was better than that of pure Ni and Cu. Incremental changes in the chromium contents within a certain range enhanced the corrosion resistance of the alloys. These alloys with 30 wt% chromium exhibited excellent anti-corrosion ability in the H _3 PO _4 solution. The electrochemical test displayed that the double capacitive loops of the alloys in the H _3 PO _4 solution increased with the chromium content; at chromium content of 30 wt%, the charge transfer resistance and activation energy were 1123 Ω and 74.10 kJ mol ^−1 , respectively. The possible corrosion-inhibition mechanism was examined by XPS, which may be owing to the formation of MoO _x (x = 1, 2, 3) and Cr _2 O _3 passivation layers in the H _3 PO _4 solution, which prevent further corrosion in acid environments

Electrochemical performance of porous Ni–Cr–Mo–Cu alloys for hydrogen evolution reactions in alkali solution

Porous Ni–Cr–Mo–Cu alloys were fabricated by an activation reaction sintering technique with Ni, Cr, Mo, and Cu element powders as raw materials. The phase constitutes, morphology, and hydrogen evolution mechanism of the electrode were characterized by x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy. The electrochemical characterization for hydrogen evolution reaction (HER) was investigated by cyclic voltammetry curves, electrochemical impedance spectroscopy, and linear sweep voltammetry. Different parameters, including Cr content, temperature, and solution concentration that affected electrocatalytic activity for HER were also considered. The results illustrated that porous Ni–Cr–Mo–Cu electrodes possessed excellent hydrogen evolution performance, and the Cr content within a certain range 15 ∼ 25 wt% improved hydrogen evolution catalytic activity. The surface roughness R _f of porous 60 wt%Ni-25 wt%Cr-10 wt%Mo-5 wt%Cu alloy electrodes was 8718.4, and the electrochemical activation energy is determined to be 7.46 kJ∙mol ^−1 , compared with 53.44 kJ∙mol ^−1 for porous 70 wt%Ni-15 wt%Cr-10 wt%Mo-5 wt%Cu alloy electrodes