Effect of Cross-Linking Density on Non-Linear Viscoelasticity of Vulcanized SBR: A MD Simulation and Experimental Study.

In recent years, there has been a growing interest in changes in dynamic mechanical properties of mixed rubber during dynamic shear, yet the influence of vulcanized characteristics on the dynamic shear behavior of vulcanized rubber, particularly the effect of cross-linking density, has received little attention. This study focuses on styrene-butadiene rubber (SBR) and aims to investigate the impact of different cross-linking densities (Dc) on dynamic shear behavior using molecular dynamics (MD) simulations. The results reveal a remarkable Payne effect, where the storage modulus experiences a significant drop when the strain amplitude (γ0) exceeds 0.1, which can be attributed to the fracture of the polymer bond and the decrease in the molecular chain's flexibility. The influence of various Dc values mainly resides at the level of molecular aggregation in the system, where higher Dc values impede molecular chain motion and lead to an increase in the storage modulus of SBR. The MD simulation results are verified through comparisons with existing literature.

A Retrospective Study of Culture-confirmed Mycobacterial Infection among Hospitalized HIV-infected Patients in Beijing, China.

A retrospective analysis was performed in two major HIV/AIDS referral hospitals in Beijing to evaluate the prevalence of Mycobacterium tuberculosis (MTB) and non-tuberculous mycobacterial (NTM) infections in HIV-infected patients. A total of 627 patients' data were reviewed, and 102 (16.3%) patients were diagnosed with culture-confirmed mycobacterial infection, including 84 with MTB, 16 with NTM, and 2 with both MTB and NTM. The most frequent clinical complication by mycobacterial infection was pulmonary infection (48/102, 47.1%). The overall rates of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) were 11.9% and 3.4%, respectively. This study underlines the urgent need to intensify screening for mycobacteria coinfection with HIV and to prevent the spread of drug-resistant TB among HIV-infected patients.

Molecular Characteristics and Drug Susceptibility of Mycobacterium tuberculosis Isolates from Patients Co-infected with Human Immunodeficiency Virus in Beijing, China.

70 clinical Mycobacterium tuberculosis strains isolated from AIDS patients in two HIV/AIDS referral hospitals in Beijing were used in this study. M. tuberculosis and non-tuberculosis mycobacterium (NTM) were identified by using multi-locus PCR. M. tuberculosis was genotyped by using 15-locus MIRU-VNTR technique and spoligotyping afterwards. Meanwhile, the drug susceptibilities of the strains to the four first-line anti TB drugs (rifampin, isoniazid, streptomycin, and ethambutol) and the four second-line anti-TB drugs (capreomycin, kanamycin, ofloxacin, and ethionanide) were tested with proportional method. In this study, M. tuberculosis and NTM strains isolated from AIDS patients with TB-like symptoms were identified and genotyping analysis indicated that Beijing genotype was the predominant genotype. In addition, the prevalence of drug-resistant TB, especially the prevalence of XDR-TB, was higher than that in TB patients without HIV infection.

[Source Analysis of Ozone and Its Precursors in Zibo Based on 3-D Air Quality Model].

Based on the ISAM module in the WRF-CMAQ model, this study analyzed the source contribution(both regional and sectoral) of O3 and its precursors(NO2 and VOCs) in Zibo in June 2021. Days with a maximum daily 8-h average(MDA8) O3 higher(lower) than 160 µg·m-3 were defined as polluted(clean) days. Differences in the source contribution between clean days and polluted days were compared, and a typical pollution period was selected for further process analysis. The results showed that NO2 in Zibo mainly came from local emissions in summer, with a relative contribution of 45.1%. Vehicle emissions(33.8%) and natural sources(20.7%) were the primary NO2 sources. VOC contributions from natural sources, solvent usage, and the petrochemical industry were significant, with a total contribution of 78.5%. The MDA8 contribution from local sources was 21.4%, whereas the impact of regional transport(32%) and surrounding cities(26.8%) was also substantial. Among local emission sources, vehicle emissions, the power industry, and the building materials industry contributed 10.9%-18.8% to local MDA8. On O3 pollution days, the MDA8 contribution from local emissions and surrounding cities increased. However, the relative contributions from local sources were similar under different pollution conditions.

[Detection and evaluation of serum GP73, a resident Golgi glycoprotein, as a marker in diagnosis of hepatocellular carcinoma].

OBJECTIVE: The aim of this study was to determine if Golgi protein-73 (GP73) is up-regulated in hepatocellular carcinoma (HCC), and to explore the possibility of using GP73 in diagnosis and treatment of HCC. METHODS: Serum GP73 was detected by a quantitative ELISA assay. A total of 372 serum samples were included, among them 43 from healthy donors (Normal), 110 from either chronic hepatitis or cirrhosis (CH/LC), and 219 from HCC patients. The levels of GP73 were compared among the 3 groups. The received operating curve (ROC), sensitivity and specificity of GP73 for HCC patients were calculated. RESULTS: The average level of GP73 expression in normal, CH/LC and HCC groups were (22.1 ± 8.5) ng/ml, (81.4 ± 57.2) ng/ml and (271.5 ± 202.3) ng/ml, respectively. Serum GP73 levels were significantly higher in patients with HCC compared to those with CH/LC (P < 0.001). The GP73 area under ROC was 0.857. Put 100 ng/ml as the optimal cut-off point, GP73 had a sensitivity of 76.7% and a specifically of 73.2%. GP73 level had a significantly higher sensitivity than AFP (32.0%) in diagnosis of early HCC (P < 0.001). Moreover, GP73 level was elevated in the serum (72.5%, 108/149) of individuals with HCC who had serum AFP level less than 400 ng/ml. Following-up study of 4 HCC patients with low level AFP indicated that GP73 was associated with treatment and prognosis of HCC. CONCLUSION: Higher level of GP73 can be found in the serum of patients with HCC than those without. GP73 is better than AFP for the diagnosis of early HCC and in evaluating treatment result in patients with normal AFP. Further studies may help to validate both the role and mechanism of GP73 in diagnosis of HCC.

Phenotype and Molecular Detection of Clarithromycin and Levofloxacin Resistance in Helicobacter pylori Clinical Isolates in Beijing.

INTRODUCTION: Understanding drug resistance is important in drug selection for Helicobacter pylori (H. pylori) eradication, and drug resistance data are lacking in Beijing. PURPOSE: This cross-sectional study aimed to isolate H. pylori from patients with gastroduodenal diseases and to analyze drug resistance to clarithromycin (CLA) and levofloxacin (LEV), which are used frequently in China. PATIENTS AND METHODS: One hundred and seventy-six patients with gastroduodenal diseases undergoing gastroduodenoscopy were selected by convenient sampling. Gastric mucosa samples were cultured and sub-cultured using a new medium broth. Active H. pylori strains were confirmed by microscopy observation as Gram-negative curved bacilli with positive test results for urease, oxidase, and catalase, and H. pylori 16S rRNA amplification by polymerase chain reaction (PCR). CLA and LEV resistance was identified by minimum inhibitory concentration (MIC) tests and sequencing of 23S rRNA, gyrA, and gyrB genes. RESULTS: From the 176 clinical samples, 112 (112/176, 63.6%) were confirmed with H. pylori infection and 65 (65/176, 36.9%) active H. pylori strains were obtained and further confirmed by MIC assay. Overall, the rates of CLA-resistant and LEV-resistant mutations in the 112 samples were 50.9% and 33.0%, respectively. Mutation related to CLA resistance was A2143G in the 23S rRNA gene and mutations associated with LEV resistance were N87K, D91G, and D91Y in the gyrA gene. Of 112 samples, 22 (19.6%) presented dual resistance to CLA and LEV. Resistance of the H. pylori strains to CLA (r=0.846, P<0.001) and LEV (r=0.936, P<0.001) had a strong correlation in phenotypic and genotypic level. CONCLUSION: The results indicated that resistance of CLA and LEV is severe among patients with gastroduodenitis. A good consistency could be found as to drug resistance between genotypic or phenotypic assay, suggested extending the detection of H. pylori drug resistance from the MIC method to a genotypic assay.

Next-generation-sequencing technology used for the detection of Mycoplasma hominis in renal cyst fluid: a case report.

Background: Mycoplasma is an opportunistic pathogen causing both urogenital and extragenital infections. The lack of cell wall renders Mycoplasma difficult to culture and identify with ordinary methods. Next-generation sequencing (NGS) is a new technology helping a lot in the diagnosis of infective diseases. In this case, NGS played a key role in the diagnosis of Mycoplasma infection. Case presentation: A mid-aged man suffering from renal cyst underwent cyst incision followed by invasive treatments to eliminate hematoma caused by renal artery hemorrhage. After the cyst incision operation, the patient had a persistent high temperature. The persistent increase of blood neutrophile granulocyte count and C-reaction protein suggested an unresolved infection. The empirically chosen anti-infective agents were meropenem and linezolid since the ordinary bacterial cultures of surgical site drainage and blood yielded a negative result. At postoperation day (POD) 17, NGS result of his drainage clearly indicated the pathogen was Mycoplasma hominis. At POD 24, the drug sensitivity test showed resistance to quinolones, clarithromycin and erythromycin, but intermediate to azithromycin. Since then, the antimicrobial agents were changed into azithromycin and kept unchanged until the patient was fully recovered and discharged at POD 39. Conclusion: When the ordinary laboratory diagnostic methods failed, NGS diagnosis could reduce the hospitalization expenses and shorten the lengths of hospital stay.

[Detection of alpha-fetoprotein-L3 using agglutinin-coupled spin column to be used in diagnosis of hepatocellular carcinoma].

OBJECTIVE: To explore the effect of use of lens culinaris agglutinin (LCA)-coupled spin column (ACSC) in detection of alpha-fetoprotein (AFP) isoform AFP-L3 and to evaluate the value of AFP-L3 as a biomarker in diagnosis of hepatocellular-carcinoma (HCC). METHODS: The serum samples of 132 patients with elevated AFP level (20-1000 microg/L), 79 diagnosed as with HCC and 53 with benign liver diseases (35 with liver cirrhosis and 18 with chronic hepatitis) underwent ACSC to isolate the fraction of AFP-L3. The contents of AFP and AFP-L3 were detected by micro-particle immunoassay. The ratio of AFP-L3 to total AFP, AFP-L3%, was calculated. Correlation between the abnormally elevated AFP-L3% and HCC was analyzed. RESULTS: Detection of AFP-L3% using ACSC method was operating friendly. The average value of AFP-L3% in the patients with HCC was 36.4%, significantly higher than those of the patients with benign liver diseases (5.3% respectively, P < 0.01). The area under the receiver operating characteristic (ROC) curve of AFP-L3% was 0.807. Taking AFP-L3% > or = 10% as diagnostic criteria, the sensitivity of AFP-L3% in HCC diagnosis was 84.8% (67/79) and the specificity was 92.5% (49/53), with a total conformity rate of 87.9% compared to the confirmed clinical diagnosis. Conclusion ACSC is of clinical value in detecting AFP-L3. AFP-L3% is a valuable biomarker in diagnosis and prediction of prognosis of HCC.

The Shape-Memory Effect of Hindered Phenol (AO-80)/Acrylic Rubber (ACM) Composites with Tunable Transition Temperature.

To broaden the types and scope of use of shape-memory polymers (SMPs), we added the hindered phenol 3,9-bis[1,1-dimethyl-2-{b-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro-[5,5]-undecane (AO-80), which comprises small organic molecules, to acrylic rubber (ACM) to form a series of AO-80/ACM rubber composites. The structural, thermal, mechanical property, and shape-memory properties of the AO-80/ACM rubber composites were investigated. We identified the formation of intra-molecular hydrogen bonding between ⁻OH of AO-80 and the carbonyl groups and the ether groups of ACM molecules. The amount of AO-80 used can be adjusted to tailor the transition temperature. AO-80/ACM rubber composites showed excellent shape recovery and fixity. The approach for adjusting the transition temperature of AO-80/ACM rubber composites provides remarkable ideas for the design and preparation of new SMPs.

RANTES gene single nucleotide polymorphisms and expression in patients with chronic hepatitis B virus infection.

BACKGROUND: Regulated on activation, normal T-cell expressed and secreted (RANTES) plays a critical role in T-lymphocyte activation and proliferation. The process is involved in both acute and chronic phases of inflammation. The present study was to ascertain the possible correlations between chronic hepatitis B virus (HBV) infection and the RANTES gene polymorphisms and their expression. METHODS: The study included 130 HBV negative healthy donors and 152 patients with chronic hepatitis B (CHB) virus infection. The polymerase chain reaction (PCR) and restriction fragment length polymorphisms (RFLPs) were used to detect RANTES gene single nucleotide polymorphisms (SNPs). RANTES levels in the platelet depleted plasma were detected by enzyme linked immunosorbent assay (ELISA). RESULTS: RANTES alleles -403G, -28C and In1.1T were the predominant alleles in the subjects studied. No significant correlation was found between CHB infection and the RANTES alleles, while a significant correlation was found between CHB infection and increased RANTES expression in platelet depleted plasma (P < 0.05). CONCLUSIONS: SNPs in RANTES gene do not affect chronic HBV infection or the outcome of interferon-alpha treatment in patients positive for HBV "e" antigen (HBeAg+). However, patients with CHB infection express the higher levels of plasma RANTES, which is thus associated with CHB infection.

A novel CCR5 mutation selectively affects immunoreactivity and fusogenic property of the HIV co-receptor.

A Nepalese heterozygous carrier of a CCR5 mutant, designated 118delF, was characterized. There was a 3 basepair deletion at 352-354 in the CCR5 open reading frame, resulting in the deletion of the phe-118 residue located in the third transmembrane domain. The mutant protein has retained antigen specificity near the third extra-cellular loop (ECL3), but that of ECL2 is markedly reduced. The mutation has also abrogated HIV co-receptor activity. Clinically, the HIV disease had progressed slowly.

Tracer-based source apportionment of polycyclic aromatic hydrocarbons in PM2.5 in Guangzhou, southern China, using positive matrix factorization (PMF).

From 28 November to 23 December 2009, 24-h PM2.5 samples were collected simultaneously at six sites in Guangzhou. Concentrations of 18 polycyclic aromatic hydrocarbons (PAHs) together with certain molecular tracers for vehicular emissions (i.e., hopanes and elemental carbon), coal combustion (i.e., picene), and biomass burning (i.e., levoglucosan) were determined. Positive matrix factorization (PMF) receptor model combined with tracer data was applied to explore the source contributions to PAHs. Three sources were identified by both inspecting the dominant tracer(s) in each factor and comparing source profiles derived from PMF with determined profiles in Guangzhou or in the Pearl River Delta region. The three sources identified were vehicular emissions (VE), biomass burning (BB), and coal combustion (CC), accounting for 11 ± 2%, 31 ± 4%, and 58 ± 4% of the total PAHs, respectively. CC replaced VE to become the most important source of PAHs in Guangzhou, reflecting the effective control of VE in recent years. The three sources had different contributions to PAHs with different ring sizes, with higher BB contributions (75 ± 3%) to four-ring PAHs such as pyrene and higher CC contributions (57 ± 4%) to six-ring PAHs such as benzo[ghi]perylene. Temporal variations of VE and CC contributions were probably caused by the change of weather conditions, while temporal variations of BB contributions were additionally influenced by the fluctuation of BB emissions. Source contributions also showed some spatial variations, probably due to the source emission variations near the sampling sites.

A new factor influencing pathogen detection by molecular assay in children with both mild and severe hand, foot, and mouth disease.

This study aimed to find novel information concerning pathogen detection and some probable coinfection factors in hand, foot, and mouth disease (HFMD). In this study, 1104 clinically diagnosed HFMD patients were included. Enterovirus 71 (EV71), coxsackievirus A16 (CA16), and 14 different respiratory pathogens were examined from nasopharyngeal swabs using polymerase chain reaction (PCR) or reverse transcriptase PCR (RT-PCR). To evaluate the immune activation in HFMD patients, 8 cytokines and IgM antibodies to EV71 and CA16 from mild and severe patients were detected. Our results indicated that the severity of HFMD may affect the pathogen detection. The lower positive rates of enterovirus and respiratory viruses in severe HFMD cases by RT-PCR were probably related to stronger immune response. Therefore, immunological tests such as ELISA are essential supplements to PCR or RT-PCR in order to increase pathogen diagnosis in HFMD, especially in severe cases.

Polycyclic aromatic hydrocarbons in PM2.5 in Guangzhou, southern China: spatiotemporal patterns and emission sources.

Fine particulate samples were simultaneously collected at six sites in Guangzhou in November-December 2009. Eighteen polycyclic aromatic hydrocarbons (PAHs) and tracers, i.e. hopanes, elemental carbon, picene and levoglucosan were measured. Three high level episodes were observed during the sampling period, likely due to accumulation effects. Back trajectory analysis revealed that the air masses for the three episodes were from eastern inland Pearl River Delta (PRD) region. There was no obvious concentration gradient for total and 5-6 ring PAHs such as benzo[g,h,i]perylene (BghiP) from urban to rural sites. However, 4-ring PAHs such as pyrene (Pyr) exhibited significantly higher levels at rural site than that at urban/suburban sites (p<0.01). BghiP correlated well with hopanes, elemental carbon and picene, indicating vehicular emissions and coal combustion were the sources of 5-6 ring PAHs, which were further confirmed by comparing the four tracers/BghiP ratios and IcdP/BghiP ratios in ambient samples with those from source profiles. Results indicated that vehicular emissions were no longer the dominant sources in winter season in Guangzhou.

[Analysis of SCCmec genotyping and antimicrobial susceptibility tests in methicillin resistant Staphylococcus aureus].

OBJECTIVE: To investigate the SCCmec genotyping, subtype and antimicrobial susceptibility tests in methicillin resistant staphylococcus aureus to guide the clinical treatment and provide the proof for molecular epidemiology. METHODS: To detect mecA gene and SCCmec genetyping and subtype in 50 MRSA by PCR. According to CLSI's guideline, antimicrobial susceptibility tests were performed with disk diffusion. RESULTS: All 50 MRSA had mecA genes. 45 strains were SCCmec III types; 3 strains were SCCmec III A types; 2 strains were SCCmec II types. There were no SCCmec I and SCCmec IV types. SCCmec II, SCCmec III and SCCmec III A type strains were all multiresistant. CONCLUSION: 50 MRSA are all multiresistant. SCCmec III are the main types.

[A transcriptional study of SDF-1alpha expression in PBL and the correlation between SDF-1alpha transcription and HIV-1 infection].

OBJECTIVE: To determine the transcription of SDF-1alpha in peripheral blood lymphocytes (PBL) and analysis the correlation between SDF-1alpha transcription and HIV infection. METHODS: Three groups of study subjects were recruited: (1) 97 HIV negative healthy donors, (2) 92 HIV patients of A1 to A3 stages and (3) 146 HIV patients of B1 to C3 stages. Total RNA was extracted from PBL. Reverse transcription (RT)-PCR and quantification PCR were developed for the SDF-1alpha transcriptional study. R1 value was calculated based on the ratio of SDF-1alpha copies to beta-globin copies. RESULTS: SDF-1alpha transcription is heterogeneous among the three study groups. The SDF-1alpha transcription was significantly up-regulated during late stage of HIV infection than the healthy donors. Correlation analysis indicated that R1 value was negatively correlated to CD4+ T cells counts (P = 0.002); and positively correlated to virus load (P = 0.001). The result demonstrated an association between SDF-1alpha transcription and disease progression. CONCLUSION: SDF-1alpha transcription was significantly up-regulated during late stage of HIV infection. It would be worthwhile to determine the mechnism of HIV affecting on SDF-1alpha genes transcription and the up-regulated SDF-1alpha expression on the disease progression.