压力与温度对炭黑填充丁苯橡胶复合材料动静态性质影响的分子模拟

采用分子动力学模拟研究了不同压力与温度对炭黑填充丁苯橡胶复合体系动静态性能的影响。结果表明,复合体系的玻璃化转变温度随着压力升高呈现线性上升;体系自由体积与分子链尺寸随着压力上升或温度下降而减小,这也导致了分子链平动扩散与旋转动力学的降低。通过计算材料储能模量、损耗模量与损耗因子,发现材料储能模量与损耗模量随着压力上升或温度下降而上升,而材料损耗因子随着压力上升或温度下降而逐渐减小。这些结果为理解水声材料在大压力宽温域环境下的性能演变提供了微观机理。

Intrathecal liproxstatin-1 delivery inhibits ferroptosis and attenuates mechanical and thermal hypersensitivities in rats with complete Freund's adjuvant-induced inflammatory pain

Previous studies have confirmed the relationship between iron-dependent ferroptosis and a peripheral nerve injury-induced neuropathic pain model.However,the role of fe rroptosis in inflammatory pain remains inconclusive.Therefore,we aimed to explore whether ferroptosis in the spinal cord and do rsal root ganglion contributes to complete Freund's adjuvant(CFA)-induced painful behaviors in rats.Our results revealed that various biochemical and morphological changes were associated with ferroptosis in the spinal cord and dorsal root ganglion tissues of CFA rats.These changes included iron overload,enhanced lipid peroxidation,disorders of anti-acyl-coenzyme A synthetase long-chain family member 4 and glutathione peroxidase 4 levels,and abnormal morphological changes in mitochondria.Intrathecal treatment of liproxstatin-1(a ferroptosis inhibitor)reve rsed these ferroptosis-related changes and alleviated mechanical and thermal hype rsensitivities in CFA rats.Our study demonstrated the occurrence of fe rroptosis in the spinal cord and do rsal root ganglion tissues in a rodent model of inflammatory pain and indicated that intrathecal administration of fe rroptosis inhibitors,such as liproxstatin-1,is a potential therapeutic strategy for treating inflammatory pain.

Prediction of Mechanical Properties of Structural Bamboo and Its Relationship with Growth Parameters

Bamboo is a renewable natural building material with good mechanical properties.However,due to the heterogeneity and anisotropy of bamboo stalk,a large amount of material performance testing costs are required in engineering applications.In this work,longitudinal compression,bending,longitudinal shear,longitudinal tensile,transverse compression and transverse tensile tests of bamboo materials are conducted,considering the influence of the bamboo nodes.The mechanical properties of the whole bamboo stalk with the wall thickness and outer circumference are explored.Through univariate and multiple regression analysis,the relationship between mechanical properties and wall thickness and perimeter is fitted,and the conversion parameters between different mechanical properties are derived.The research results show that the transverse compressive strength of nodal specimen,and transverse tensile strength of nodal and inter-node specimens increase with the increase of wall thickness and outer circumference,but other mechanical properties decrease with the increase of wall thickness and outer circumference.The prediction formula and conversion parameters of bamboo mechanical properties proposed in this research have high applicability and accuracy.Moreover,this research can provide references for the evaluation of bamboo performance and saving test costs.

Effect of posture on ^(13)C-urea breath test in partial gastrectomy patients

AIM: To investigate whether posture affects the accuracy of 13C-urea breath test(13C-UBT) for Helicobacter pylori(H. pylori) detection in partial gastrectomy patients. METHODS: We studied 156 consecutive residual stomach patients, including 76 with H. pylori infection(infection group) and 80 without H. pylori infection(control group). H. pylori infection was confirmed if both the rapid urease test and histology were positive during gastroscopy. The two groups were divided into four subgroups according to patients' posture during the 13C-UBT: subgroup A, sitting position; subgroup B, supine position; subgroup C, right lateral recumbent position; and subgroup D, left lateral recumbent position. Each subject underwent the following modified 13C-UBT: 75 mg of 13C-urea(powder) in 100 m L of citric acid solution was administered, and a mouth wash was performed immediately; breath samples were then collected at baseline and at 5-min intervals up to 30 min while the position was maintained. Seven breathsamples were collected for each subject. The cutoff value was 2.0‰.RESULTS: The mean delta over baseline(DOB) values in the subgroups of the infection group were similar at 5 min(P > 0.05) and significantly higher than those in the corresponding control subgroups at all time points(P < 0.01). In the infection group, the mean DOB values in subgroup A were higher than those in other subgroups within 10 min and peaked at the 10-min point(12.4‰± 2.4‰). The values in subgroups B and C both reached their peaks at 15 min(B, 13.9‰± 1.5‰; C, 12.2‰± 1.7‰) and then decreased gradually until the 30-min point. In subgroup D, the value peaked at 20 min(14.7‰± 1.7‰). Significant differences were found between the values in subgroups D and B at both 25 min(t = 2.093, P = 0.043) and 30 min(t = 2.141, P = 0.039). At 30 min, the value in subgroup D was also significantly different from those in subgroups A and C(D vs C: t = 6.325, P = 0.000; D vs A: t = 5.912, P = 0.000). The mean DOB values of subjects with Billroth Ⅰ anastomosis were higher than those of subjects with Billroth Ⅱ anastomosis irrespectively of the detection time and posture(P > 0.05).CONCLUSION: Utilization of the left lateral recumbent position during the procedure and when collecting the last breath sample may improve the diagnostic accuracy of the 13C-UBT in partial gastrectomy patients.

Study on the pre-treatment of oxidized zinc ore prior to flotation

The pre-treatment of zinc oxide bearing ores with high slime content is important to ensure that resources are utilized optimally. This paper reports an improved process using hydrocyclone de-sliming, dispersion reagents, and magnetic removal of iron minerals for the pre-treatment of zinc oxide ore with a high slime and iron content, and the benefits compared to traditional technologies are shown. In addition, this paper investigates the damage related to fine slime and iron during zinc oxide flotation, the necessity of using hydrocyclone de-sliming together with dispersion reagents to alleviate the influence of slime, and interactions among hydrocyclone de-sliming, reagent dispersion, and magnetic iron removal. Results show that under optimized operating conditions the entire beneficiation technology results in a flotation concentrate with a Zn grade of 34.66% and a recovery of 73.41%.

Clinical Analysis of Transcatheter Embolotherapy for Congenital Pulmonary Arteriovenous Fistulas in Children

Objective:To summarize the clinical features and therapeutic effects of transcatheter embolotherapy for congenital pulmonary arteriovenous fi stulas(PAVFs)in children,and to explore the method and therapeutic principle of transcatheter embolotherapy for congenital PAVFs in children.Method:We retrospectively reviewed nine patients with PAVF who underwent transcatheter embolotherapy in the Children’s Hospital of Chongqing Medical University from July 2004 to July 2019,including the demographic characteristics,clinical manifestations,effi ciency of closure,and follow-up.Results:Transcatheter embolotherapy was successful in all cases,and the symptom remission rate was 100%during the follow-up.No residual shunts or other complications occurred during the follow-up period.Compared with before embolotherapy,there were signifi cant changes in the percentage of saturated oxyhemoglobin and total hemoglobin level at the last follow-up(t=10.06,P=0.000;t=3.055,P=0.0076).No signifi cant difference was observed in pulmonary artery pressure before and after embolotherapy(t=0.13,P=0.90).Conclusions:Transcatheter embolotherapy offers the advantages of safety,with a decreased risk of trauma and a specifi c effect of treatment,and therefore is recommended as the fi rst-line treatment for congenital PAVFs in children.However,continued research is necessary to understand the full potential of transcatheter embolotherapy.

Association between MTHFR c.677C>T variant and erectile dysfunction among males attending fertility clinic

Genetic risk factors have been shown to contribute to the development of sexual dysfunction.However,the role of methylenetetrahydrofolate reductase(MTHFR)gene variants in the risk of erectile dysfunction(ED)remains unclear.In this study,we recruited 1254 participants who underwent ED assessed by the International Index of Erectile Function-5.The MTHFR c.677C>T variant was also measured by fluorescence polymerase chain reaction(PCR).No significant difference in the genotypic frequency of the MTHFR C677T polymorphism(CC,CT,and TT)was observed between men from the ED and non-ED groups.In addition,on binary logistic regression analysis,both crude and adjusted models showed that the risk of ED was not significantly associated with the C677T polymorphism.Interestingly,a significantly higher frequency of the 677TT polymorphism was found in severe and moderate ED(P=O.02).The positive correlation between the MTHFR 677TT polymorphism and severe ED was confirmed by logistic regression analysis,even after adjusting for potential confounders(odds ratio[OR]=2.46,95%confidence interval[CI]:1.15-5.50,P=0.02).These findings suggest a positive correlation between the MTHFR 677TT polymorphism and the risk of severe ED.Identification of MTHFR gene polymorphisms may provide complementary information for ED patients during routineclinicaldiagnosis.

水平地震下钢-混凝土组合框架结构极限抗震与强柱构造

“强柱弱梁”是当前国际上主流的工程结构抗震设计理念,已有地震灾害调查表明,由于地震作用机制的复杂性以及对工程结构极限抗震认识的不足,强震作用后框架结构除出现梁铰的“强柱弱梁”破坏之外,还出现整体倒塌、柱铰以及局部楼层倒塌的“强梁弱柱”破坏。为合理认识各类破坏形式,首先对传统的塑性铰概念细分为“压铰”和“拉铰”,指出“拉铰”容易引发结构整体失稳;随后以钢-混凝土组合框架结构为对象,建立并采用实体单元与壳单元为主的组合框架结构有限元精细化抗震计算模型,开展组合结构极限抗震分析,初步探讨各水平地震波工况对组合框架结构位移、应力、轴压比等时程响应以及框架梁柱塑性耗能分配机制、塑性铰形成模式与失效机制的影响规律。分析结果显示:1)柱端拉筋减小了钢管与混凝土之间滑移,从而增大了柱和框架的刚度,降低了钢管和混凝土的应变水平,增大了钢梁的应力水平;620 cm/s^(2)及以上强度的地震波作用时,柱端拉筋构造可显著减小组合框架结构的最大层间位移角,在接近极限强度的水平地震波作用时,柱端拉筋屈服,框架梁端混凝土板纵筋一般不易屈服;2)“强梁弱柱”组合框架表现为“约束梁”与“耗能柱”,此时框架梁对框架柱约束较强,框架以框架柱耗能为主而梁端仅形成“压铰”,此时框架的耗能能力取决于框架柱;“强柱弱梁”组合框架表现为“耗能梁”与“承载柱”,此时框架梁对框架柱约束较弱,框架以框架梁耗能为主使得梁端先形成“压铰”,当梁端耗能至极限时形成“拉铰”引发框架柱长细比增大,导致框架加速失效,不利于发挥框架柱耗能潜力;3)柱端拉筋技术的“强柱”构造将提高组合结构的刚度、塑性耗能与抗倒塌能力,强柱构造对以柱耗能为主的6层框架抗震能力提升尤其显著。

Numerical studies on the seismic response of a three-storey low-damage steel framed structure incorporating seismic friction connections

A 9 m high,near full scale three-storey configurable steel frame compositefloor building incorporating frictionbased connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering(ILEE)facilities,Shanghai,China,as part of the RObust BUilding SysTem(ROBUST)project.A total of nine structural configurations are designed and detailed.To have a better understanding of the expected system behaviour,as well as effects of other structural and non-structural elements(NSEs)on the overall system response,experimental testing at component level has been conducted prior to the shake table testing.This paper presents an introduction to the ROBUST project,followed by a numerical study on one of the nine configurations of the structure,having Moment Resisting Steel Frame(MRSF)in the longitudinal direction and Concentrically Braced Frame(CBF)in the transverse direction.Hysteretic properties employed in the numerical models are validated against component test results.The predictions of the building’s seismic response under selected base excitations are presented indicating the likely low damage performance of the structure.

Current status of hair analysis in forensic toxicology in China

Hair analysis has been mainly used to document drug use history in abusers,drug-facilitated crime cases,doping control analysis and postmortem toxicology in the fields of forensic toxicology,clinical toxicology,and doping control.Hair analysis has also gained more attention in the last 30 years in China.Relevant technology has been promoted as more research has appeared concerning hair analysis,and consensus has been sought among forensic toxicologists regarding aspects such as hair decontamination treatment,detection of abused substances in hair,segmental hair analysis and interpretation of analytical results.However,there are still some limitations in the estimation of drug intake time and frequency by segmental hair analysis due to the different growth cycles evident within a bundle of hairs,the drug incorporation mechanism and sampling errors.Microsampling and imaging mass spectrometry(iMS)technology based on a single hair may be a good choice to estimate drug intake time more accurately.Analysis of hair root samples may also be used to document acute poisoning in postmortem toxicology,and the analysis of the hair shaft can document long-term use of drugs depending on the length of the hair being evaluated.

Determination of barbiturates in hair samples by using a validated UHPLC-HRMS method: application in investigation of drug-facilitated sexual assault

In recent years,benzodiazepines and benzodiazepine-like drugs are the most common substances associated with drug-facilitated sexual assaults(DFSA);however,barbiturates are also detected occasionally.Segmental hair analysis provides useful information on the historic pattern of drug use,enabling differentiation between single exposure in DFSA cases and chronic use.However,sensitive and specific methods for barbiturate analysis in hair samples are needed.Herein,we present an ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry(UHPLC-HRMS)method for qualitative and quantitative determination of seven barbiturates in hair samples.Firstly,a hair strand was decontaminated and then freeze-milled in liquid nitrogen.Next,50mg of powdered hair was extracted with methanol in an ultrasonic bath for 10 min in the presence of 10 ng phenobarbital-d5.The supernatant was dried under nitrogen gas,and the pellet was dissolved in 100 μL mobile phase.Afterwards,10 μL of the suspension was injected into the UHPLC-HRMS system.The present method involved two UHPLC conditions for determination of barbiturates(I)and identification of the structural isomers amobarbital and pentobarbital(II).This method showed satisfactory linearity in a range of 0.02–20.00 ng/mg for UHPLC conditions I and II,both with a high determination coefficient(0.9991–0.9999).The selectivity,intra-and interday precision,accuracy and matrix effect of the method were acceptable.Next,the validated method was applied to investigate an authentic DFSA case.Hair samples(black,approximate 25cm long)were collected 3 months after the assault,and the proximal segments(0–5 cm from the root;each segment was 1 cm long)were analysed.Amobarbital was detected at a concentration of<LOQ(limit of quantification)and 0.09 ng/mg in the second and third 1-cm hair segment but not in the other segments.Thus,our method was successful in determining barbiturate concentration in human hair after a single-dose exposure,showing its potential for application in the investigation of DFSA cases.

Anticoagulant rodenticide intoxication in east China:a three-year analysis

The study was designed to analyze the incidence and pattern of anticoagulant rodenticide intoxication in east China and to discuss strategies of diagnosis based on laboratory analysis experience.A total of 117 patients with anticoagulant rodenticide poisoning confirmed by toxicological analysis in east China were included in this study from 2011 to 2013.The mean concentration of anticoagulant rodenticide,age,and gender of these patients,as well as the mode and type of poisoning,were discussed.The age ranged from less than 1 to 80 years with the feeble preponderance of males(M D 53.0%,F D 47.0%).The 0–9 age group covered the largest ratio of these anticoagulant rodenticide poisoning patients.Accidental or voluntary ingestion seems to be the most common cause of intoxication,with still the poisoning cause being unknown for a large number of positive analyses.Bromadiolone was the most commonly observed anticoagulant rodenticide found in the biological samples,followed by brodifacoum.The concentrations of bromadiolone and brodifacoum that were detected in the first collected whole blood from each patient ranged from 1 to 878 ng/mL(mean 97.9 ng/mL)and from 0.5 to 1566 ng/mL(mean 225.1 ng/mL),respectively.The data analysis shows a high incidence of anticoagulant rodenticide poisoning without awareness of the poisoned subjects,clearly emphasizing the need for toxicological analysis in patients with vitamin K-dependent coagulation disorder and restriction on availability of anticoagulant rodenticide.

Acoustic cloak constructed with thin-plate metamaterials

We propose a strategy for designing the cylindrical acoustic cloak with thin-plate metamaterials.The inhomogeneous cloaking shell as derived by transformation acoustics is first discretized into a three-layer anisotropic metafluid,and their material parameters are optimized by minimizing the external scatterings.Then these metafluids are practically realized by thin-plate structures according to the metamaterial concept.As an example,an acoustic cloak is designed with nine layers of thin plate and totally 900 plate units.Numerical simulations are performed to assess the cloaking performance of the designed structure.

Screening for volatile sulphur compounds in a fatal accident case

Acute fatal poisoning due to the inhalation of toxic gas frequently occurs in China.Volatile sulphur compounds(VSCs)are toxic to humans.In fatal poisoning investigations,such as those in industrial settings,a number of VSCs,including methanethiol(MT),dimethyl sulphide(DMS),dimethyl disulphide(DMDS)and dimethyl trisulphide(DMTS),can coexist.To date,there is limited data regarding these compounds in post-mortem cases.In the present study,we report toxicological findings in a fatal accident case with two victims.Headspace gas chromatography/flame ionization detector with two columns of different polarities was utilized to screen MT,DMS,DMDS and DMTS in blood.The limits of detection in both methods were 0.05 mg/mL.No sulphur compounds were detected in the blood samples of the two victims.DMS and DMDS were detected in the lungs at concentrations of 0.5 and 1.3 mg/g and 2.2 and 4.1 mg/g,respectively.DMDS liver concentrations were 2.5 and 6.5 mg/g.In addition to hydrogen sulphide,screening for additional VSCs could help establish the cause of death.

Herbicide 2,4-dichlorophenoxyacetic acid interferes with MAP kinase signaling in Fusarium graminearum and is inhibitory to fungal growth and pathogenesis

Plant hormones are important for regulating growth,development,and plant-pathogen interactions.Some of them are inhibitory to growth of fungal pathogens but the underlying mechanism is not clear.In this study,we found that hyphal growth of Fusarium graminearum was significantly reduced by high concentrations of IAA and its metabolically stable analogue 2,4-dichlorophenoxyacetic acid(2,4-D).Besides inhibitory effects on growth rate,treatments with 2,4-D also caused significant reduction in conidiation,conidium germination,and germ tube growth.Treatments with 2,4-D had no obvious effect on sexual reproduction but significantly reduced TRI gene expression,toxisome formation,and DON production.More importantly,treatments with 2,4-D were inhibitory to infection structure formation and pathogenesis at concentrations higher than 100μM.The presence of 1000μM 2,4-D almost completely inhibited plant infection and invasive growth.In F.graminearum,2,4-D induced ROS accumulation and FgHog1 activation but reduced the phosphorylation level of Gpmk1 MAP kinase.Metabolomics analysis showed that the accumulation of a number of metabolites such as glycerol and arabitol was increased by 2,4-D treatment in the wild type but not in the Fghog1 mutant.Transformants expressing the dominant active FgPBS2^(S451D T455D) allele were less sensitive to 2,4-D and had elevated levels of intracellular glycerol and arabitol induced by 2,4-D in PH-1.Taken together,our results showed that treatments with 2,4-D interfere with two important MAP kinase pathways and are inhibitory to hyphal growth,DON biosynthesis,and plant infection in F.graminearum.

Multi-locus identification of Psilocybe cubensis by high-resolution melting(HRM)

Hallucinogenic mushroom is a kind of toxic strain containing psychoactive tryptamine substances such as psilocybin,psilocin and ibotenic acid,etc.The mushrooms containing hallucinogenic components are various,widely distributed and lack of standard to define,which made a great challenge to identification.Traditional identification methods,such as morphology and toxicology analysis,showed shortcomings in old or processed samples,while the DNA-based identification of hallucinogenic mushrooms would allow to identify these samples due to the stability of DNA.In this paper,four primer sets are designed to target Psilocybe cubensis DNA for increasing resolution of present identification method,and the target markers include largest subunit of RNA polymerase II(marked as PC-R1),psilocybin-related phosphotransferase gene(marked as PC-PT),glyceraldehyde 3-phosphate dehydrogenase(marked as PC-3)and translation EF1α(marked as PC-EF).Real-time PCR with high-resolution melting(HRM)assay were used for the differentiation of the fragments amplified by these primer sets,which were tested for specificity,reproducibility,sensitivity,mixture analysis and multiplex PCR.It was shown that the melting temperatures of PC-R1,PC-PT,PC-3 and PC-EF of P.cubensis were(87.93±0.12)℃,(82.21±0.14)℃,(79.72±0.12)℃ and(80.11±0.19)℃ in our kinds of independent experiments.Significant HRM characteristic can be shown with a low concentration of 62.5pg/µL DNA sample,and P.cubensis could be detected in mixtures with Homo sapiens or Cannabis sativa.In summary,the method of HRM analysis can quickly and specifically distinguish P.cubensis from other species,which could be utilized for forensic science,medical diagnosis and drug trafficking cases.

Dynamic changes of serum protein in rats with acute intoxication of Chinese cobra snake venom by proteomic analysis

To elucidate the toxic mechanism of snake venom at the protein level,proteomics technol-ogy was applied to investigate the effect of venom on circulation in the mammalian body.Temporal proteomic analysis was performed to profile the dynamic changes in the sera of Sprague-Dawley rats administered with Chinese cobra venom or saline.Using 8-plex iTRAQ analysis,392 and 636 serum proteins were identified to be linearly upregulated or downre-gulated over time in the low-dose group and high-dose group,respectively.These proteins were mainly associated with the acute phase response pathway,complement system,and liver X receptor(LXR)/retinoid X receptor(RXR)and farnesoid X receptor(FXR)/RXR activation pathways.Compared with the low-dose group,the immune response and integrin pathways were inhibited in the high-dose group,although no obvious effect was observed.With con-sistently higher or lower expression in the high-dose group compared to the low-dose group throughout the whole process of venom poisoning,two proteins,Kininogen-1(KNG1)and orosomucoid 1(ORM1),which are involved in metabolism and immune response,occu-pied a core position in the pathway network and are considered venom dose-dependent biomarker candidates.

Segmental hair analysis for flunitrazepam and 7-aminoflunitrazepam in users:a comparison to existing literature

The availability of more quantitative data on flunitrazepam(FLU)and 7-aminoflunitrazepam(7AF)would aid in obtaining a better understanding of the interpretation of FLU concentrations in human hair.The purpose of this study was to provide concentrations of FLU and 7AF in hair segments of 22 FLU users.Quantitative data regarding hair concentrations of FLU and 7AF from various types of cases were also reviewed to give a comprehensive overview of the comparability of different studies.Three to six 1 cm segments of scalp hair from 22 FLU users were analyzed by a liquid chromatography–tandem mass spectrometry(LC–MS/MS)method.FLU and its metabolite were confirmed in the hair segments from all cases.Concentrations of FLU and 7AF in the segments ranged from 0.01–0.16 ng/mg(median of 0.03)and 0.01–0.34 ng/mg(median of 0.09),respectively.Most cases had FLU and 7AF distributions along the hair segments that were suggestive of repeated drug use.A summary of the published concentrations gives valuable data and can assist forensic investigators in their estimations of drug use history and patterns.