草酸预处理AM50镁合金表面快速原位制备 蒸汽Mg−Al LDH涂层的耐蚀性

通过暴露合金表面的金属间化合物(β-Mg17Al12和AlMn),研究草酸(OA)酸洗对AM50镁合金表面原位蒸汽Mg−Al层状双氢氧化物(LDH)涂层成膜机制和耐蚀性的影响。结果表明,OA预处理使镁合金表面金属间化合物比例显著增加,Mg−Al LDH在Al−Mn相周围成核并生长。当酸洗时间为45 s时,所得LDH涂层的厚度最大、耐蚀性最佳,与基体相比,其腐蚀电流密度降低3个数量级。最后,提出了AM50镁合金表面Mg−Al LDH涂层的成膜机制。

Brain networks in newborns and infants with and without sensorineural hearing loss:A functional near-infrared spectroscopy study

BACKGROUND Understanding the impact of early sensory deficits on brain development is essential for understanding developmental processes and developing potential interventions.While previous studies have looked into the impact of prenatal experiences on language development,there is a lack of research on how these experiences affect early language and brain function development in individuals with sensorineural hearing loss(SNHL).AIM To investigate SNHL effects on early brain development and connectivity in 4-month-olds vs healthy newborns and controls.METHODS The research involved analyzing the functional brain networks of 65 infants,categorized into three groups:28 healthy newborns,224-month-old participants with SNHL,and 15 age-matched healthy participants.The resting-state functional connectivity was measured and compared between the groups using functional near-infrared spectroscopy and graph theory to assess the brain network properties.RESULTS Significant differences were found in resting-state functional connectivity between participants with SNHL and age-matched controls,indicating a developmental lag in brain connectivity for those with SNHL.Surprisingly,SNHL participants showed better connectivity development compared to healthy newborns,with connectivity strengths of 0.13±0.04 for SNHL,0.16±0.08 for controls,and 0.098±0.04 for newborns.Graph theory analysis revealed enhanced global brain network properties for the SNHL group,suggesting higher communication efficiency at 4 months.No significant differences were noted in network properties between 4-month-old SNHL participants and neonates.A unique pattern of central hubs was observed in the SNHL group,with 2 hubs in the left hemisphere compared to 6 in controls.CONCLUSION 4-month-old infants with SNHL have a distinct brain network pattern with efficient long-distance information transmission but less effective local communication compared to age-matched controls.

Corrosion resistance of Mg-Al-LDH steam coating on AZ80 Mg alloy:Effects of citric acid pretreatment and intermetallic compounds

In this study,the effects of intermetallic compounds(Mg_(17)Al_(12)and Al_(8)Mn_(5))on the Mg-Al layered double hydroxide(LDH)formation mechanism and corrosion behavior of an in-situ LDH/Mg(OH)_(2)steam coatings on AZ80 Mg alloy were investigated.Citric acid(CA)was used to activate the alloy surface during the pretreatment process.The alloy was first pretreated with CA and then subjected to a hydrothermal process using ultrapure water to produce Mg-Al-LDH/Mg(OH)_(2)steam coating.The effect of different time of acid pretreatment on the activation of the intermetallic compounds was investigated.The microstructure and elemental composition of the obtained coatings were analyzed using FE-SEM,EDS,XRD and FT-IR.The corrosion resistance of the coated samples was evaluated using different techniques,i.e.,potentiodynamic polarization(PDP),electrochemical impedance spectrum(EIS)and hydrogen evolution test.The results indicated that the CA pretreatment significantly influenced the activity of the alloy surface by exposing the intermetallic compounds.The surface area fraction of Mg_(17)Al_(12)and Al_(8)Mn_(5)phases on the surface of the alloy was significantly higher after the CA pretreatment,and thus promoted the growth of the subsequent Mg-Al-LDH coatings.The CA pretreatment for 30 s resulted in a denser and thicker LDH coating.Increase in the CA pretreatment time significantly led to the improvement in corrosion resistance of the coated AZ80 alloy.The corrosion current density of the coated alloy was lower by three orders of magnitude as compared to the uncoated alloy.

Advances in Mg-Al-layered double hydroxide steam coatings on Mg alloys:A review

Layered double hydroxide(LDH)coatings on magnesium(Mg)alloys shine brightly in the field of corrosion protection because of their special ion-exchange function.State-of-the-art steam coating as a type of LDH film preparation technique has emerged in recent years because only pure water is required as the steam source and its environmentally friendly LDH coating fits the current need for green development.Moreover,this coating can effectively inhibit the corrosion of the Mg alloy substrate due to the chemical bonding between the coating and the Mg alloy substrate.This review systematically explains cutting-edge advancements in the growth mechanism and corrosion behavior of LDH steam coatings,and analyzes the advantages and limitations of the steam-coating method.The influencing factors including pressure,CO_(2)/CO_(3)^(2-),aluminum content of the substrate alloy,solution type,and acid-pickling pretreatment,as well as the post-treatment of steam-coating defects,are comprehensively elucidated,providing new insights into the development of the in situ steam-coating technique.Finally,existing issues and future prospects are discussed to further accelerate the widespread application of Mg alloys.

In vitro corrosion resistance and antibacterial properties of layer-by-layer assembled chitosan/poly-L-glutamic acid coating on AZ31 magnesium alloys

Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer(LbL)assembly of chitosan(CHI)and poly-L-glutamic acid(PGA)by electrostatic attraction.The functionalized surfaces of the Mg alloys were characterized by field-emission scanning electron microscopy(FE-SEM),Fourier transform infrared(FT-IR)spectroscopy and electrochemical tests.The bactericidal activity of the samples against Staphylococcus aureus was assessed by the zone of plate-counting method.The obtained coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance.

Corrosion resistance of Mg−Al LDH/Mg(OH)2/silane−Ce hybrid coating on magnesium alloy AZ31

An environmentally-friendly hybrid coating on AZ31 magnesium alloy substrates was reported.The synergic effect was studied on Mg−Al-layered double hydroxide Mg−Al LDH/Mg(OH)2-coated AZ31 magnesium alloy via an in-situ steam coating process and a subsequent combined surface modification of bis-[triethoxysilylpropyl]tetrasulfide(BTESPT)silane and Ce(NO3)3.The microstructure and composition characteristics of the hybrid coatings were investigated by means of X-ray diffraction(XRD),scanning electronic microscopy(SEM),Fourier transform infrared spectrophotometry(FT-IR)and X-ray photoelectron spectroscopy(XPS).The corrosion resistance of the coated samples was evaluated by potentiodynamic polarization(PDP),electrochemical impedance spectrum(EIS)and hydrogen evolution rate during immersion in 3.5 wt.%NaCl solution.The results show an improved corrosion resistance of the alloy in the presence of BTESPT silane and Ce(NO3)3.This is most likely due to the synergistic effect of steam coating and silane coating to enhance the barrier properties of hybrid coating.In addition,the formation mechanism and anti-corrosion mechanism of coatings were discussed.

Identification and characterization of two novel cathelicidins from the frog Odorrana livida

Antimicrobial peptides(AMPs) are a group of gene-encoded small peptides that play pivotal roles in the host immune system of multicellular organisms.Cathelicidins are an important family of AMPs that exclusively exist in vertebrates. Many cathelicidins have been identified from mammals, birds, reptiles and fish. To date, however, cathelicidins from amphibians are poorly understood. In the present study, two novel cathelicidins(OL-CATH1 and 2) were identified and studied from the odorous frog Odorrana livida.Firstly, the cDNAs encoding the OL-CATHs(780 and735 bp in length, respectively) were successfully cloned from a lung cDNA library constructed for the frog. Multi-sequence alignment was carried out to analyze differences between the precursors of the OL-CATHs and other representative cathelicidins.Mature peptide sequences of OL-CATH1 and 2 were predicted(33 amino acid residues) and their secondary structures were determined(OL-CATH1 showed a random-coil conformation and OL-CATH2 demonstrated α-helical conformation). Furthermore,OL-CATH1 and 2 were chemically synthesized and their in vitro functions were determined. Antimicrobial and bacterial killing kinetic analyses indicated that OL-CATH2 demonstrated relatively moderate and rapid antimicrobial potency and exhibited strong anti-inflammatory activity. At very low concentrations(10 μg/mL), OL-CATH2 significantly inhibited the lipopolysaccharide(LPS)-induced transcription and production of pro-inflammatory cytokines TNF-α, IL-1βand IL-6 in mouse peritoneal macrophages. In contrast, OL-CATH1 did not exhibit any detectableantimicrobial or anti-inflammatory activities. Overall,identification of these OL-CATHs from O. livida enriches our understanding of the functions of cathelicidins in the amphibian immune system. The potent antimicrobial and anti-inflammatory activities of OL-CATH2 highlight its potential as a novel candidate in anti-infective drug development.

Color-related chlorophyll and carotenoid concentrations of Chinese kale can be altered through CRISPR/Cas9 targeted editing of the carotenoid isomerase gene BoaCRTISO

The carotenoid isomerase gene(BoaCRTISO)of Chinese kale was targeted and edited using the CRISPR/Cas9 system in the present study.The results showed a high mutation rate(81.25%),and 13 crtiso mutants were obtained.Only two types of mutations,insertions and replacements,were found.Both the total and individual carotenoid and chlorophyll concentrations of the biallelic and homozygous mutants were reduced,and the total levels declined by 11.89–36.33%.The color of the biallelic and homozygous mutants changed from green to yellow,likely reflecting a reduction in the color-masking effect of chlorophyll on carotenoids.The expression levels of most carotenoid and chlorophyll biosynthesis-related genes,including CRTISO,were notably lower in the mutants than in the WT plants.In addition,the functional differences between members of this gene family were discussed.In summary,these findings indicate that CRISPR/Cas9 is a promising technique for the quality improvement of Chinese kale and other Brassica vegetables.

Study on the effect of RDX content on the properties of nitramine propellant

Four kinds of nitroamine propellants with different RDX contents(10%,20%,30%and 40%)were prepared to study the effect of RDX content on the mechanical properties and combustion properties of nitroamine propellant.The mechanical properties and combustion properties of nitroamine propellant at the normal temperature(20C)and low temperature(à40C)were test by using impact testing machine,drop hammer impact test machine and closed bomb vessel.The test results show that the impact strength of30%RDX-contained nitramine propellant is maximum,but 40%RDX-contained nitramine propellant has the minimum impact strength.And the crushing height of propellant with 20%RDX-contained was the highest,but the crushing height of propellant with 40%RDX-contained the lowest.With the increase in RDX content in nitramine propellant,the energy of nitramine propellant increases and its burning rate reduces,but 40%RDX-contained nitramine propellant did not meet this trend at the low temperature because of its poor mechanical properties.

Influence of intermetallic Al-Mn particles on in-situ steam Mg-Al-LDH coating on AZ31 magnesium alloy

The influence of intermetallic Al-Mn particles on the corrosion behavior of in-situ formed Mg-Al layered double hydroxide(Mg-Al-CO32--LDH)steam coating on AZ31 Mg alloy was investigated.The alloy was pretreated with H3PO4,HCl,HNO3or citric acid(CA),followed by hydrothermal treatment,for the fabrication of Mg-Al-LDH coating.The microstructure,composition and corrosion resistance of the coated samples were investigated.The results showed that the surface area fraction of Al-Mn phase exposed on the surface of the alloy was significantly increased after CA pretreatment,which promotes the growth of the Mg-Al-LDH steam coating.Further,the LDH-coated alloy pretreated with CA possessed the most compact surface and the maximum coating thickness among all the coatings.The corrosion current density of the coated alloy was decreased by three orders of magnitude as compared to that of the bare alloy.

Effects of C-terminal amidation and heptapeptide ring on the biological activities and advanced structure of amurin-9KY, a novel antimicrobial peptide identified from the brown frog, Rana kunyuensis

Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cloned from synthesized double-strand skin cDNA of R.kunyuensis.The amurin-9KY precursor was composed of 62 amino acid (aa) residues,whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring (Rana box domain) and an amidated C-terminus.These structural characters represent a novel amphibian AMP family.Although amurin-9KY exhibited high similarity to the already identified amurin-9AM from R.amurensis,little is known about the structures and activities of amurin-9 family AMPs so far.Therefore,amurin-9KY and its three derivatives (amurin-9KY1-3) were designed and synthesized.The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9KY..Results indicated that C-terminal amidation was essential for antimicrobial activity,whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity.Circular dichroism (CD) spectra showed that the four peptides adopted an α-helical conformation in THF/H2O (v/v 1∶1) solution,but a random coil in aqueous solution.Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity.Scanning electron microscopy (SEM) was also performed to determine the possible bactericidal mechanisms.

Design of fast crystallization of nanosized zeolite omega crystals at higher temperatures

Fast crystallization of nanosized zeolite crystals is a very popular process used for practical zeolite catalyst applications. Herein, we report a designer crystallization process for nanosized zeolite omega crystals based on the relationship between the crystallization time and temperature in the Arrhenius equation. Compared to the conventional hydrothermal synthesis of zeolite omega(72 h at room temperature and 240 h at 100℃, MAZ-100), the crystallization of zeolite omega presented in this work only requires a very short time interval(5 h at 180℃, MAZ-180). Physicochemical characterizations, including XRD, SEM, N2 sorption isotherms, and 27 Al MAS NMR show that the product of zeolite omega(MAZ-180) has good crystallinity and uniform nanocrystals. More importantly, after the loading of Pt nanoparticles(0.5 wt%), the Pt/H-MAZ-180 catalyst exhibits higher isomer selectivity and lower cracking selectivity than those of the Pt/H-MAZ-100 catalyst in the hydroisomerization of n-dodecane. These results suggest the potential applications of these omega nanocrystals as supporting catalyst compounds in industrial processes.

Population Structure Analysis and Genome-Wide Association Study of Tea(Camellia sinensis(L.)Kuntze)Germplasm in Qiannan,China,Based on SLAF-Seq Technology

Duyun Maojian tea is a famous tea in China.In this study,the specific-locus amplified fragment(SLAF)sequencing method was used to analyze the population structure and conduct a genome-wide association study(GWAS)of 2 leaf traits of 123 tea plants in Qiannan,China.A total of 462,019 SLAF tags and 11,362,041 single-nucleotide polymorphism(SNP)loci were obtained.The results of phylogenetic tree analysis,cluster analysis,and principal component analysis showed that 123 tea germplasms were clustered into three groups,and the heterozygosity rates for Groups I,II,and II were 0.206,0.224,and 0.34,respectively.Generally,tea germplasms in a production area are clustered in a group,indicating that tea germplasms in different production areas have certain genetic diversity.The traditional Duyun Maojian tea core production areas,TS and DC-SJ,are clustered into Group I and Group II respectively,while the ZY production area is relatively independent in Group III.Furthermore,based on GWAS analysis,11 candidate genes related to leaf apex and 7 candidate genes related to leaf shape were obtained.This study clarified the genetic relationship among eight Duyun Maojian tea production areas and obtained candidate genes related to leaf apex and leaf shape development.The results showed that population structure and candidate genes are an effective basis for the breeding of Duyun Maojian tea germplasm.

Cloning and Characterization of EuGID1 in Eucommia ulmoides Oliver

Gibberellic acid controlled the key developmental processes of the life cycle of landing plants,and regulated the growth and development of plants.In this study,a novel gibberellin receptor gene EuGID1 was obtained from Eucommia ulmoides Oliver.The cDNA of EuGID1 was 1556 bp,and the open reading frame was 1029 bp,which encoded 343 amino acids.EuGID1 had the homology sequence with the hormone-sensitive lipase family.Amino acid sequence alignment confirmed EuGID1 protein had the highest homology with the GID1 protein of Manihot esculenta.EuGID1 was located in the nucleus and cell membrane and had expression in four plant organs.Overexpression of EuGID1 in transgenic Arabidopsis plants promoted plant elongation and increased siliques yield.

Effects of astragalus polysaccharides on ventricular remodeling and miRNA-21 in rats with acute myocardial infarction

Objective:To investigate the effect of Astragalus polysaccharides(APS)on myocardial remodeling and expression of miR-21 after myocardial infarction.Methods:Sixty SPF grade healthy male rats were divided into the sham operation group,the model group,astragalus polysaccharide low,medium and high dose groups and atorvastatin group randomly with 10 rats in each group.The left anterior descending coronary artery(LAD)was ligated to establish myocardial infarction model in rats,and the corresponding drug intervention was given for 4 weeks.The changes of myocardial morphology and collagen were observed by HE and Masson staining.The levels of IL-1β,IL-6,TNF-αand IL-10 were detected by ELISA.The mRNA expressions of miR-21,MMP2,TIMP-2,Col-I,and Col-III was detected by RT-PCR.The protein expressions of TLR4,MyD88 and NF-κB p65 were detected by Western blot.Results:Compared with the model group,APS could improve the pathological morphology of myocardial tissue,increase the level of IL-10 in myocardial tissue,reduce the staining area of collagen and the contents of IL-1β,IL-6 and TNF-α(P<0.05).At the same time,APS could decreased the expression of MMP2,Col-I and Col-ⅢmRNA and the ratio of MMP2/TIMP-2,and increased the expression of TIMP-2 mRNA and miR-21 significantly(P<0.05).Furthermore,APS could significantly reduce the expression of TLR4,p-NF-κB p65 and MyD88 protein in myocardial tissue of rats with myocardial infarction,and the differences were statistically significant when compared with the model group(P<0.05).Conclusion:APS can inhibit the activation of TLR4/MyD88/NF-κB signaling pathway by upregulating the expression of miR-21,which plays a therapeutic role in ventricular remodeling after acute myocardial infarction.

Corona virus disease 2019-associated liver injury in cold regions

The corona virus disease 2019(COVID-19)pandemic has created a global health and economic crisis.Our studies uncovered that in addition to respiratory symptoms,liver damage is also common in COVID-19 patients;however,the cause of liver damage has not been fully elucidated.In this article,we summarize the clinical manifestations and pathological features of COVID-19 reported in published relevant studies and delineate the etiology and pathogenesis of COVID-19-related liver injury.We speculate that cold stimulation may be associated with COVID-19-related liver injury,which should be considered in clinical decision-making and treatment of COVID-19 in cold regions.

Professor Ruixia Pei's Experience in Treating Hyperthyroidism

In this article,we summarize the clinical experience ofProfessor Ruixia Pei,a famous traditional Chinese medicine practitioner in Shaanxi Province,China,in treating hyperthyroidism.The etiology and pathogenesis,syndrome differentiation,and medication experience are introduced in detail.This paper summarizes the advantages of Professor Pei's methods of syndrome differentiation and treatment of hyperthyroidism.This may help enrich the clinical treatment of hyperthyroidism,and provide some diagnosis and treatment ideas.

Professor Ruixia Pei's Clinical Experience in Treating Globus Hystericus with"Harmonizing Method"

To summarize professor Pei9s experience in treating globus hystericus.Methods:Learn from your teacher.Results:Professor Pei had been suffering from the disease for more than 30 years and had her unique views on the treatment of globus hystericus,which are mostly for emotional dysfunction,liver Qi is not comfortable,functioning of Qi is not adjusted,Yin and Yang imbalance.The basic principle of treatment is to grasp the core pathogenesis,take harmony as the method and balance as the duration,harmonize Qi,regulate Yin and Yang,use drugs to disperse the liver and rectify Qi,as well as auxiliary treatment with products to promote blood circulation,remove blood stasis,dryness and dampness,and clear heat.

Ruixia Pefs Experience in the Treatment of Hypothyroidism

This study is to summarize Professor Pei's experience in treating hypothyroidism.Professor Pei has been engaged in clinical endocrinology for more than 30 years and has unique insights into hypothyroidism.She believes that the disease is caused by liver depression,phlegm binding,yin deficiency,and fire effulgence.The basic principles of treatment are regulating Qi movement and harmonizing viscera.During treatment,the emphasis is on the influence of emotions on the disease.Both the liver and spleen should be given equal attention and the medication should be mild with balanced cold and heat.

A comprehensive research on wear resistance of GH4169 superalloy in longitudinal-torsional ultrasonic vibration side milling with tool wear and surface quality

To improve the service and machining performance of the workpiece, the tool wear mechanisms, surface machining quality, and wear resistance in conventional side milling(CSM)and longitudinal-torsional ultrasonic vibration side milling(LTUVSM) of GH4169 superalloy at different cutting lengths are investigated systematically. Tool wear mechanisms are revealed and the correlation between machined surface quality with tool wear is analyzed correspondingly. Tool wear patterns mainly include adhesive wear, diffusion wear, abrasive wear, and chipping sticking.Better surface quality is achieved in LTUVSM due to a maximum reduction of flank wear bandwidth and wear rate by 71.9% and 71.5%, respectively, compared to CSM. The friction coefficient,initial wear stage time, and wear volume of dry sliding wear were measured to evaluate the workpiece wear resistance. The maximum reductions in friction coefficient and wear volume in LTUVSM are 18.2% and 15.8% compared to CSM. The regular ultrasonic vibration textures suppress the friction and the growth of contact nodes in the contact area, decreasing the degree of surface wear, which is demonstrated by a 38.8% increase in initial wear stage time compared to CSM.In conclusion, the workpiece in LTUVSM exhibits higher wear resistance because of the improvement of tool wear and the guarantee of surface quality.