Search

The role of δ-Fe in hydrogen embrittlement (HE) of 17-4 PH steel is studied in this work. Scanning Kelvin probe force microscopy result indicates that δ-Fe is a hydrogen trapping site. Accordingly, δ-Fe can reduce the hydrogen concentration of surrounding martensite and prior austenite grain boundaries (PAGBs) and imped the brittle fracture along lath boundaries and PAGBs, which can be beneficial to the HE resistance improvement. However, a cleavage fracture of δ-Fe can occur under the synergetic action of hydrogen-enhanced localized plasticity (HELP) and hydrogen enhancement of the strain-induced generation of vacancies (HESIV). These findings indicate a new path to improving HE resistance of high strength martensitic steels. • SKPFM result shows that hydrogen tends to segregate in delta ferrite. • Delta ferrite acting as a hydrogen trapping site decreases the tendency of brittle fracture. • Hydrogen segregation in delta ferrite leads to a strain localization and a subsequent transgranular cleavage fracture. [ABSTRACT FROM AUTHOR]

Abstract: F-doped SnO2 (SnO x :F) films deposited on a glass substrate by atmospheric pressure chemical vapor deposition (APCVD) were annealed at 600°C for different times. The effects of annealing time on the structural, optical and photoluminescence (PL) properties of SnO x :F films were investigated. The results show that all the films have a polycrystalline cassiterite tetragonal crystal structure and exhibit obviously preferred orientations with (200) and (310) planes. The films annealed for 15min possess the smallest particle sizes, of 94.95nm, and a minimum root mean square roughness of 15.74nm. The transmittances of all the films in the visible range can reach ∼80%. When the annealing time increases from 0 to 60min, the optical band gap of SnO x :F films decreases from 3.91 to 3.87eV. The room temperature PL spectra show weak UV emission, intense violet emission and broad and weak blue emission. The violet emission related to F substitutions and oxygen vacancies is composed of three PL subbands centered at 3.22, 3.03 and 2.81eV. The photoemission position is observed to be independent of annealing time. [Copyright &y& Elsevier]

Abstract: The microstructure, compression property and work-hardening effect of the NiAl-matrix composite reinforced by 5 vol.% ceramic particulates (TaB and TaB2) were investigated. The compression properties and work-hardening capacity (H c) under the different strain rates were also investigated. The NiAl-matrix composite has strong strain rate sensitivity. A high true ultimate strength of 1399 MPa, a true fracture strain of 18.7% and H c = 1.84 were obtained under the strain rate of 1.0 × 10−4 s−1. The good compression properties may be attributed to the refinement of the grain size and the good combination between the ceramic particulates and the NiAl-matrix. [Copyright &y& Elsevier]

Abstract: The microstructure, compression property and work-hardening effect of the NiAl-matrix composite with 1.7wt.% NbB2 and Nb x C (x =1 or 2) fabricated by the combustion synthesis and hot pressing technique have been investigated in the study. The NiAl-matrix composite has strong strain rate sensitivity. The yield strength of the NbB2–Nb x C/NiAl composite decreases while the fracture strain and the work-hardening capacity (H c) increase with decreasing strain rate. A high true ultimate strength of 1472MPa, a fracture strain of 20.1% and H c =1.41 were obtained under the strain rate of 2.0×10−5 s−1. [Copyright &y& Elsevier]

Abstract: As one of the primary methods of cryogenic refrigeration, reverse Brayton cycle cryocooler, which includes high-speed turbine using gas bearing and compact heat exchanger, has many advantages such as long-life, high reliability and efficiency. In this paper general aspects of reverse Brayton cycle cryocooler in China are introduced, such as its application in the space simulation program, mechanical cryocooler for lower temperature space applications. The main design parameters and operating performance of cryocoolers are presented in this paper. [Copyright &y& Elsevier]

The binary tetragonal intermetallic compound Mo5Si3 has significant thermal expansion anisotropy (TEA) with the coefficient of thermal expansion (CTE) of the c-axis (αc) more than double that of the a-axis (αa). Since boron has been shown to improve the oxidation stability of alloys near this composition, we explore the effect of adding boron on the thermal expansion anisotropy of Mo5+ySi3−yBx (T1) and subsequently the adjoining phases in thermal equilibrium. Powder X-ray diffraction was conducted at high temperatures using high energy (>40 keV) synchrotron X-rays. All of the intermetallics in this system (Mo5SiB2, MoSi2, MoB and Mo3Si) have moderate CTE values ranging from 7.17 ppm/°C for the cubic Mo3Si to nearly 14 ppm/°C for the c-axis of Mo5Si3B. The nearly isotropic TEA for Mo5B2Si was confirmed. The variability of the TEA of Mo5Si3B from 1.83 to 2.43 is explained in terms of the site occupancy and the change of the inter-atomic spacing of the Mo atom chains along the c-axis. [Copyright &y& Elsevier]

Abstract: The purpose of these experiments is to investigate the possibility to use power ultrasound to remove iron-rich coatings from the surfaces of silica sand for glass making. Experiments show that the iron-rich coating on a particle surface of silica sand with 0.18% Fe2O3 was reduced to 0.11% with powerful ultrasonic an experiment set-up from our own design. The treatment time and chemical reagent were varied to determine the optimum conditions. Some electrolytes will be useful to eliminate iron. [Copyright &y& Elsevier]

Abstract: Background: Intimal hyperplasia plays an important role in vein graft stenosis. Inflammatory injury, especially nuclear factor kappaB (NF-κB) gene activation, is highly involved in stenosis progression. We examined whether neointimal hyperplasia and vein graft stenosis could be inhibited by silencing the NF-κB gene with small interference RNA (siRNA). Methods: Sixty adult male Sprague-Dawley rats were randomly divided into a normal vein group, a vein graft group, a scrambled siRNA group, and an NF-κB siRNA group. We performed reverse interpositional grafting of the autologous external jugular vein to the abdominal aorta. Vein grafts were treated with liposome and gel complexes containing NF-κB siRNA or scrambled siRNA. The levels of monocyte chemoattractant protein -1, tumor necrosis factor-α, and NF-κB p65 in vessel tissues were evaluated after surgery for content of proliferating cell nuclear antigen (PCNA) and vascular wall thickness. Results: NF-κB siRNA treated vein graft showed less neointimal formation and fewer positive PCNA cells (P < .05). In addition there were lower levels of, NF-κB p65 protein and of inflammatory mediators (P < .05) compared with the vein graft group. Conclusion: Our study suggested that siRNA transfection suppressed NF-κB expression, reduced inflammatory factors, lessened neointimal proliferation, and suppressed PCNA. [Copyright &y& Elsevier]

Abstract: Creep behavior of the unmodified and modified cast Al–Cu alloys was investigated at temperatures from 393 to 483K in the tension test. The creep resistance ability of the Al–Cu alloy modified by Pr x O y is almost 3–5 times as high as that of the unmodified Al–Cu alloy, which is attributed to a large number of nano-scale θ′ precipitates with high thermal stability in the modified Al–Cu alloy restricting and impeding the dislocation movement during the creep. The induction of a threshold stress in the analysis leads to a stress exponent of 5, which suggests that the creep behavior of both the present alloys is associated with the lattice diffusion-controlled dislocation climb (n =5). [Copyright &y& Elsevier]

Posttranslational modifications, mostly phosphorylation, are critical for protein structure and function. However, the association between liver phosphoproteins in neonatal calves and colostrum intake is not well understood. In this study, we examined the liver phosphoproteome profile in neonatal calves after receiving colostrum or milk. Liver tissue samples were collected from control calves (CON, n = 3) 2 h after birth and from calves that received colostrum (CG, n = 3) or milk (MG, n = 3) 24 h after birth. Hepatic phosphoprotein expression profiles were analyzed using quantitative proteomics based on the liquid chromatography–tandem mass spectrometry method. In total, 1,587 phosphorylated sites were identified in 1,011 liver proteins. The most abundant phosphorylation site AA was serine (87.5%), followed by threonine (11.9%) and tyrosine (0.5%). Among the 1,011 phosphoproteins, 219, 453, and 26 displayed differential expression in the CG versus MG, CG versus CON, and MG versus CON comparisons, respectively. Differentially expressed phosphoproteins in the CG–MG comparison included 3-phosphoinositide-dependent protein kinase 1, glucose transporter member 4, protein kinase N2, and vinculin, which were mainly involved in the glycogen metabolic process, transport, growth and development, and cell adhesion process, according to Gene Ontology analysis. Pathway analysis indicated their enrichment in the insulin signaling pathway, spliceosome, and adherens junction. The CG–CON comparison identified differentially expressed phosphoproteins and their target genes that were largely involved in the cellular process, macromolecule metabolic process, developmental process, and transport. Pathway analysis indicated their association with endocytosis, mechanistic target of rapamycin, AMP-activated protein kinase, and insulin signaling pathways. These data demonstrate that changes in the phosphoproteins of liver tissues may play an important role in energy metabolism and immune response in the calves that received colostrum. These results provide novel insights into the crucial roles of protein phosphorylation during the early life of newborn calves. [ABSTRACT FROM AUTHOR]

The contribution of colostrum to passive immunity transfer and intestinal protection is well known; however, the effects of colostrum intake on the expression of antimicrobial peptides (AP) and Fc receptors in the intestine of neonatal calves are unclear. Our aim was to investigate changes in the expression of AP and Fc receptor in the small intestine of calves in the first 36 h postpartum. Twenty-four Holstein bull calves were used in this study, of which 18 calves were administered 3.2 L of pooled colostrum for each calf per meal via an esophageal tube. Calves were slaughtered at 8 h (1 meal at 1–2 h), 24 h (2 meals at 1–2 h and 10–12 h), and 36 h (3 meals at 1–2 h, 10–12 h, and 22–24 h) postpartum. The remaining 6 calves without any milk administration were slaughtered at 2 h postpartum. Samples of blood and jejunum digesta were collected to determine immunoglobulin concentration using ELISA. Samples of the duodenum, jejunum, and ileum tissues after slaughter were collected to determine AP and Fc receptor expression using quantitative real-time PCR. In calves administered colostrum, IgG concentration in jejunum digesta rapidly decreased in an age-dependent manner (33.41, 9.47, and 0.34 mg/mL at 8, 24, and 36 h, respectively), whereas serum IgG concentration increased significantly, from 0.25 μg/mL at 2 h to 21.72 mg/mL at 24 h. Cathelicidin-4, β-defensin (DEFB)-7, and enteric β-defensin expression was upregulated at 8 h postpartum in the duodenum and jejunum compared with that at 2 h, but progressive recovery was detected from 24 h onward. Higher expression of cathelicidin-4, regenerating family member 3γ, lysozyme (LYZ), LYZ1 , and LYZ2 and lower expression of DEFB , DEFB1 , DEFB7 , DEFB10 , and enteric β-defensin were observed in the duodenum and jejunum compared with the ileum. Differences in AP expression between intestinal regions suggested that the innate immune defense mechanism varied significantly among the duodenum, jejunum, and ileum. No difference in the expression of Fc fragment of the IgG receptor was observed either among ages or small intestinal regions. The Fcγ receptor (FcγR) Ia and FcγRIIb expression was the highest at 8 h compared with that at 2, 24, and 36 h, and expression of FcγRIa , Fc γ RIIb , and FcγRIIIa was higher in the duodenum and jejunum than in the ileum. These results indicated that AP and Fcγ receptors might play important roles in intestinal defense during the passive immunity period. [ABSTRACT FROM AUTHOR]

Circular RNA (circRNA) have been suggested to contribute to regulating gene expression in various tissues and cells of eukaryotes. However, little is known regarding the expression pattern of circRNA and their potential function in the small intestine of neonatal calves that receive colostrum. In the current study, jejunum tissue samples were collected from control calves (2 h after birth; CT; n = 3) and neonatal calves that ingested colostrum (24 h after birth; CO; n = 3) or milk (24 h after birth; MK; n = 3) to compare the circRNA expression patterns using a high-throughput RNA sequencing approach. A total of 21,213, 17,861, and 21,737 circRNA were identified in the CT, CO, and MK groups, respectively. Only 13,254 of these circRNA were common to the 3 groups, suggesting high specificity of circRNA expression depending on nutrient type. In total, 243, 249, and 283 circRNA were differentially expressed in the CO versus CT, CO versus MK, and MK versus CT comparisons, respectively. Gene ontology analysis showed that the differentially expressed circRNA and their predicted or known target genes from the CO and MK groups were mainly involved in macromolecule metabolic process, response to stress, and vesicle-mediated transport. Moreover, pathway analysis showed that the Rap1 signaling pathway, focal adhesion, ubiquitin-mediated proteolysis, and extracellular matrix–receptor interaction were the most significantly enriched pathways. These data collectively indicate that circRNA are abundant and dynamically expressed when calves receive colostrum and act as microRNA sponges to regulate their target genes for jejunum function during the early development of newborn calves. [ABSTRACT FROM AUTHOR]

Uptake of colostrum is of central importance for establishing a passive immunity transfer in neonatal calves. Studies of absorption and transmission of colostral immunoglobulins have been widely reported; however, changes in the serum in response to the absorption of colostral components in neonatal calves have not been completely characterized. Here, a nuclear magnetic resonance-based metabolomics approach was used to investigate the changes in metabolites in ingested colostrum, milk, and serum after neonatal calves were fed colostrum or milk. Twenty-seven neonatal male Holstein calves were assigned to 1 of the following groups: (1) calves not fed colostrum or milk and slaughtered approximately 2 h after birth (control group, n = 6), (2) calves fed colostrum at 1 to 2 h after birth and slaughtered 8 h after birth (n = 6), (3) calves fed 2 colostrum meals (at 1–2 and 10–12 h after birth) and slaughtered 24 h after birth (n = 6), (4) calves fed 3 colostrum meals (at 1–2, 10–12, and 22–24 h after birth) and slaughtered 36 h after birth (n = 6), or (5) calves fed 2 milk meals (1–2 and 10–12 h after birth) and slaughtered 24 h after birth (n = 3). Concentrations of valine, leucine, lactate, lysine, and isoleucine were higher and concentrations of lactose were lower in the groups fed colostrum and milk compared with groups not fed colostrum and milk, respectively. Metabolite changes between groups fed or not fed colostrum and milk were similar and may reflect the primary metabolic requirements of ingestion by the small intestine of neonatal calves. Concentrations of serum metabolites choline, valine, leucine, and glutamate were higher in the serum of calves that received colostrum compared with control calves. Furthermore, concentrations of serum phenylalanine, valine, and glutamate were significantly higher, whereas serum concentrations of citrate and very low density lipoproteins were lower in calves that received colostrum compared with calves fed milk. Our results indicate that concentrations of leucine, valine, and glutamate, which were higher in the calves that ingested colostrum, may transfer into the bloodstream, and that these metabolites are associated with health benefits in the neonatal calves that received colostrum. These findings provide novel information to help us understand the mechanism by which colostrum components are metabolized and absorbed in the small intestine and then transferred into bloodstream of neonatal calves. [ABSTRACT FROM AUTHOR]

Highly textured F-doped SnO 2 (FTO) films with appropriate haze, high transparency and low resistance have been deposited on quartz glass substrates by spray pyrolysis technique at different substrate temperatures from 380 °C to 630 °C. The results show that all FTO films with pyramidal-shape grains are polycrystalline with cassiterite tetragonal structure and exhibit an obviously (200) preferred orientation. When the substrate temperature is 530 °C, the dislocation density of FTO films reaches a minimum value of 1.90 × 1015 line/m2, while the film thickness and root-mean-square roughness reach the maximum values of 613 nm and 32.3 nm, respectively. Highly textured FTO films sprayed at 530 °C exhibit the lowest turn on voltage of 1.95 eV and the optimal comprehensive optoelectrical performance with the high transmittance of 83.78%, low sheet resistance of 8.4 Ω/□ and high haze of 12.69%, which are the promising candidates as the transparent conductive oxide front electrode for film solar cells. • Highly textured FTO film with obviously (200) preferred orientation was sprayed. • FTO films sprayed at 530 °C are the promising candidates for front electrode. • Haze reaches a maximum value of 12.69% at 530 °C. • The figure of merit reaches a maximum value of 20.29 × 10−3 Ω−1 at 530 °C. [ABSTRACT FROM AUTHOR]