Pectin modulates intestinal immunity in a pig model via regulating the gut microbiota-derived tryptophan metabolite-AhR-IL22 pathway

Background Pectin is a heteropolysaccharide that acts as an intestinal immunomodulator,promoting intestinal development and regulating intestinal flora in the gut.However,the relevant mechanisms remain obscure.In this study,pigs were fed a corn-soybean meal-based diet supplemented with either 5%microcrystalline cellulose(MCC)or 5%pectin for 3 weeks,to investigate the metabolites and anti-inflammatory properties of the jejunum.Result The results showed that dietary pectin supplementation improved intestinal integrity(Claudin-1,Occludin)and inflammatory response[interleukin(IL)-10],and the expression of proinflammatory cytokines(IL-1β,IL-6,IL-8,TNF-α)was down-regulated in the jejunum.Moreover,pectin supplementation altered the jejunal microbiome and tryptophan-related metabolites in piglets.Pectin specifically increased the abundance of Lactococcus,Enterococcus,and the microbiota-derived metabolites(skatole(ST),3-indoleacetic acid(IAA),3-indolepropionic acid(IPA),5-hydroxyindole-3-acetic acid(HIAA),and tryptamine(Tpm)),which activated the aryl hydrocarbon receptor(AhR)pathway.AhR activation modulates IL-22 and its downstream pathways.Correlation analysis revealed the potential relationship between metabolites and intestinal morphology,intestinal gene expression,and cytokine levels.Conclusion In conclusion,these results indicated that pectin inhibits the inflammatory response by enhancing the AhR-IL22-signal transducer and activator of transcription 3 signaling pathway,which is activated through tryptophan metabolites.

Experimental and theoretical studies on two-dimensional vanadium carbide hybrid nanomaterials derived from V_(4)AlC_(3) as excellent catalyst for MgH_(2)

Hydrogen is considered one of the most ideal future energy carriers.The safe storage and convenient transportation of hydrogen are key factors for the utilization of hydrogen energy.In the current investigation,two-dimensional vanadium carbide(VC) was prepared by an etching method using V_(4)AlC_(3) as a precursor and then employed to enhance the hydrogen storage properties of MgH_(2).The studied results indicate that VC-doped MgH_(2) can absorb hydrogen at room temperature and release hydrogen at 170℃. Moreover,it absorbs 5.0 wt.%of H_(2) within 9.8 min at 100℃ and desorbs 5.0 wt.% of H_(2) within 3.2 min at 300℃.The dehydrogenation apparent activation energy of VC-doped MgH_(2) is 89.3 ± 2.8 kJ/mol,which is far lower than that of additive-free MgH_(2)(138.5 ± 2.4 kJ/mol),respectively.Ab-initio simulations showed that VC can stretch Mg-H bonds and make the Mg-H bonds easier to break,which is responsible for the decrease of dehydrogenation temperature and conducive to accelerating the diffusion rate of hydrogen atoms,thus,the hydrogen storage properties of MgH_(2) are remarkable improved through addition of VC.

Facile synthesis of a Ni_(3)S_(2)@C composite using cation exchange resin as an efficient catalyst to improve the kinetic properties of MgH_(2)

Carbon materials have excellent catalytic effects on the hydrogen storage performance of MgH2. Here, carbon-supported Ni3S2(denoted as Ni3S2@C) was synthesized by a facile chemical route using ion exchange resin and nickel acetate tetrahydrate as raw materials and then introduced to improve the hydrogen storage properties of MgH2. The results indicated the addition of 10 wt.% Ni3S2@C prepared by macroporous ion exchange resin can effectively improve the hydrogenation/dehydrogenation kinetic properties of MgH2. At 100 ℃,the dehydrogenated MgH2-Ni3S2@C-4 composite could absorb 5.68 wt.% H2. Additionally, the rehydrogenated MgH2-Ni3S2@C-4 sample could release 6.35 wt.% H2at 275 ℃. The dehydrogenation/hydrogenation enthalpy changes of MgH2-Ni3S2@C-4 were calculated to be 78.5 k J mol-1/-74.7 k J mol-1, i.e., 11.0 k J mol-1/7.3 k J mol-1lower than those of MgH2. The improvement in the kinetic properties of MgH2was ascribed to the multi-phase catalytic action of C, Mg2Ni, and Mg S, which were formed by the reaction between Ni3S2contained in the Ni3S2@C catalyst and Mg during the first hydrogen absorption–desorption process.

Improvement of Sliding Performance for Ball on Disc Tribo-Partners Using Graphite Like Carbon Solid Lubricant Coating

Sliding wear tests of chilled cast iron tappet-disc and cam-ball tribo-partners were conducted by using ball on disc testing device. Magnetron sputtering CrTiAlN hard coating and Graphite like carbon (GLC) solid lubricant coatings were applied on either one or both of the contact surfaces on tribo-partners. Ball crater device and scanning electron microscope were used to investigate surface wear of rubbed track on disc and wear scar on ball. The sliding performances of tribo-partners were evaluated in terms of coefficient of friction at sliding surfaces and specific wear rate (SWR) on both of the rubbed surfaces under specific test conditions. All test results showed that GLC solid lubricant coating on both surfaces of tappet-disc and cam-ball was the best option to allow this tribo-partners having high performance in terms of sliding under high load with low coefficient of friction and low SWR. The advantage of using GLC solid lubricant coating is to enable mechanical parts made of ordinary and sustainable materials (e.g. cast iron or plain steels) to be operated under even harsher conditions of higher load and higher wear environment with improved performance.

钢筋混凝土系杆拱桥设计分析及稳定性计算

利用有限元空间分析模型,对某60m钢筋混凝土系杆拱进行了设计分析,同时计算了有风撑和无风撑两种状况下拱桥的空间稳定性,结果表明:该桥承载能力极限状态和正常使用极限状态下正截面应力及斜截面应力,以及弹性使用阶段拱肋、系杆、横梁截面应力验算均满足规范要求,有风撑的结构更加加强了桥梁结构的稳定性。

Heat stress-induced mucosal barrier dysfunction is potentially associated with gut microbiota dysbiosis in pigs

Heat stress(HS)can be detrimental to the gut health of swine.Many negative outcomes induced by HS are increasingly recognized as including modulation of intestinal microbiota.In turn,the intestinal microbiota is a unique ecosystem playing a critical role in mediating the host stress response.Therefore,we aimed to characterize gut microbiota of pigs’exposure to short-term HS,to explore a possible link between the intestinal microbiota and HS-related changes,including serum cytokines,oxidation status,and intestinal epithelial barrier function.Our findings showed that HS led to intestinal morphological and integrity changes(villus height,serum diamine oxidase[DAO],serum D-lactate and the relative expressions of tight junction proteins),reduction of serum cytokines(interleukin[IL]-8,IL-12,interferongamma[IFN-g]),and antioxidant activity(higher glutathione[GSH]and malondialdehyde[MDA]content,and lower superoxide dismutase[SOD]).Also,16S rRNA sequencing analysis revealed that although there was no difference in microbial a-diversity,some HS-associated composition differences were revealed in the ileum and cecum,which partly led to an imbalance in the production of short-chain fatty acids including propionate acid and valerate acid.Relevance networks revealed that HS-derived changes in bacterial genera and microbial metabolites,such as Chlamydia,Lactobacillus,Succinivibrio,Bifidobacterium,Lachnoclostridium,and propionic acid,were correlated with oxidative stress,intestinal barrier dysfunction,and inflammation in pigs.Collectively,our observations suggest that intestinal damage induced by HS is probably partly related to the gut microbiota dysbiosis,though the underlying mechanism remains to be fully elucidated.

Chronic heat stress induces the disorder of gut transport and immune function associated with endoplasmic reticulum stress in growing pigs

Although high temperatures influence gut health,data on underlying mechanisms remains scant.Using a pig model,this study performed a global analysis on how chronic heat stress affects the transport and immune function of the gut through transcriptome,proteome,microbial diversity and flow cytometry.A total of 27 pigs with similar body weights were assigned into 3 groups,control(Con)group(23℃),chronic heat stressed(HS)group(33°C),and pair-fed(PF)group,in a controlled environment for 21 days.Our results showed that pigs in the HS group had reduced growth performance and diminished height of ileal villi(P<0.01).Transcriptome and proteome analyses demonstrated notable modification of expression of nutrients and ion transport-related transporters and gut mechanical barrier-related genes by chronic heart stress(P<0.05),suggesting damage of transport functions and the gut barrier.Chronic heat stress-induced endoplasmic reticulum stress also increased the synthesis of misfolded proteins,leading to upregulation of misfolded protein degradation and synthesis,as well as vesicle transport disorder(P<0.05).Energy supply processes were enhanced in the mitochondrion(P<0.05)to maintain biological processes with high energy demands.Furthermore,chronic heat stress activated complement cascade response-related genes and proteins in the gut mucosa(P<0.05).Our flow cytometry assays showed that the proportion of gut lymphocytes(CD4^(+)T cells,T cells,B cells in Peyer’s patch lymphocytes and CD4^(+)CD25^(+)T cells in intraepithelial lymphocytes)were significantly altered in the HS group pigs(P<0.05).In addition,the occurrence of gut microbial dysbiosis in the HS group pigs was characterized by increased potential pathogens(e.g.,Asteroleplasma,Shuttleworthia,Mycoplasma)and suppression of beneficial bacteria(e.g.,Coprococcus and Aeriscardovia),which are associated with gut immune function.Altogether,our data demonstrated that chronic heat stress induced gut transport and immune function disorder associated with endoplasmic reticulum stress in growing pigs.

High-temperature friction behavior of amorphous carbon coating in glass molding process

In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated temperature.To improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron sputtering.The friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the mold.Therefore,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high temperature.Meanwhile,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction strength.The friction coefficient between the glass and coating depended on the temperature.Besides,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition diffusion.This work provides a better understanding of the application of carbon coatings in the glass molding.