First principles studies on the electronic and contact properties of single layer 2H-MoS2/1T'-MX2 heterojunctions.

Constructed via in-plane heterojunction contacts between the semiconducting 2H phase (as the channel) and the metallic 1T' phase (as the electrode), two-dimensional (2D) transition metal dichalcogenide (TMD) field-effect transistors (FETs) have received much recent attention because they significantly reduce contact resistance. In this paper, ab initio quantum transport simulation is done to study and predict the electronic states and contact properties of the 2H-MoS2/1T'-MX2 (WS2, TaSe2, NbSe2, MoSe2, TaS2, and NbS2) in-plane heterojunctions. It is found that the interfacial states are not obvious and the fluctuation of the average electron density at the 1T'/2H phase boundary is small for all 2H-MoS2/1T'-MX2 heterojunctions. The average electrostatic potential differences (ΔV) are all negative, which is beneficial to promote the charge transfer from 1T'-MX2 to 2H-MoS2. Moreover, the p-type Schottky contact of the 2H-MoS2/1T'-MX2 heterojunctions is formed and the ΦSB,P values are 0.609 eV, 0.625 eV, 0.641 eV, 0.617 eV, 0.469 eV and 0.477 eV for 1T'-WS2, 1T'-TaSe2, 1T'-NbSe2, 1T'-MoSe2, 1T'-TaS2, and 1T'-NbS2, respectively. The results provide theoretical guidance for designing two-dimensional material devices.

Exploration of (3-benzyl-5-hydroxyphenyl)carbamates as new antibacterial agents against Gram-positive bacteria.

A series of (3-benzyl-5-hydroxyphenyl)carbamates were evaluated as new antibacterial agents. Several compounds showed potent inhibitory activity against sensitive and drug-resistant Gram-positive bacteria. The compounds are ineffective against all tested Gram-negative bacteria. The structure of the ester group exerted a profound effect on antibacterial activity. 4,4-Dimethylcyclohexanyl carbamate 6h exhibited the most potent inhibitory activity against the standard and clinically isolated Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis (minimum inhibitory concentration = 4-8 µg/ml) strains. The preliminary experimental evidence indicated that these carbamates target the bacterial cell wall and share a similar mechanism of action with vancomycin.

ZTW-41, a Potent Indolizinoquinoline-5,12-Dione Derivative Against Drug-Resistant Staphylococci and Enterococci Bacteria.

ZTW-41, an indolizinoquinoline-5,12-dione derivative, was investigated for antibacterial activity against Gram-positive bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). In our study, the MIC90s (minimum inhibitory concentrations) of ZTW-41 against MRSA (MRSA, n = 200), methicillin-sensitive S. aureus (MSSA, n = 100), Enterococcus faecalis (E. faecalis, n = 32), and Enterococcus faecium (E. faecium n = 32) were 0.25, 0.25, 0.125, and 8 µg/mL, respectively, whereas the MBC90s (minimum bactericidal concentrations) were 2, 1, 1, and >32 µg/mL, respectively. ZTW-41 maintained its potency at different pH levels (range 5-9) and in starting inoculum size up to 107 CFU/mL. The presence of human serum (25-75%) increased ZTW-41 MICs by two- to eightfold. Time-kill curves showed that ZTW-41 had bactericidal activity against MRSA, MSSA, and E. faecalis strains within 8 hours, and rebound growth occurred after 8 hours except at higher multiples of the MIC (4 × and 8 × ). In the acute toxicity study, no mortality or signs of toxicity was noted in mice after 14 days of observation at doses <50 mg/kg. ZTW-41 exhibited good selectivity indices (SIs) (SI = IC50/MIC90) ranging from 1.12 to 71.76 against clinical isolates, demonstrating excellent therapeutic selectivity in MRSA, MSSA, and E. faecalis strains. Moreover, the in vivo efficacy (effective dose [ED]50 = 6.59 mg/kg) of ZTW-41 was found comparable with vancomycin. Collectively, our favorable results supported ZTW-41 as a promising investigational candidate for treating drug-resistant bacteria infection.

[Frequencies of autoantibodies specific for primary biliary cirrhosis in a general adult population group].

OBJECTIVE: To investigate the frequencies of primary biliary cirrhosis (PBC)-specific autoantibodies, including antimitochondrial autoantibodies (AMA) M2, anti-gp210 and anti-Sp100, and to assess their point prevalence rates in a general adult population group in Guangzhou. METHODS: Eight thousand one hundred twenty-six adults (mean age 43.5+/-14.6 years, range 18 to 83 years; 4248 males and 3878 females) were enrolled for this study. AMA and anti-nuclear antibodies (ANA) were screened by indirect immunofluorescence test and AMA-M2, anti-gp210 and anti-sp100 were further detected using ELISA or immunoblotting assay. PBC diagnosis was made according to criteria recommended by AASLD in 2000. RESULTS: Of the 8126 adults tested, 35 (0.43%) and 79 (0.97%) were found to be positive for AMA and ANA. The positivity for both of AMA and ANA increased with aging. Twenty-two cases were positive for PBC-specific autoantibodies. Frequencies for AMA-M2, anti-sp100 and anti-gp210 in the general adult population were 0.23%, 0.05% and 0.04% respectively and their frequency reached 0.62% in women over 40 years. A woman among the 22 cases who was PBC-specific autoantibody positive was finally diagnosed as a PBC patient. CONCLUSION: Our data indicates that PBC specific autoantibodies exist in the general adult population at very low frequencies and the point prevalence rate of PBC in adults in Guangzhou is not less than that of other areas.

Syntheses and antibacterial activity of soluble 9-bromo substituted indolizinoquinoline-5,12-dione derivatives.

In our previous research, 9-bromo indolizinoquinoline-5,12-dione 1 has been found to be a good anti-MRSA agent. However, it had very low bioavailability in vivo possibly due to its low solubility in water. In order to obtain the derivatives with higher anti-MRSA activity and good water solubility, twenty eight bromo-substituted indolizinoquinoline-5,12-dione derivatives were synthesized in the present study. The antibacterial activity of the synthesized compounds was evaluated against one gram-negative and some gram-positive bacterial strains including 100 clinical MRSA strains. The UV assays were carried out to determine the solubility of six active compounds 16, 21, 23 and 27-29. The most potent compound 28 exhibited strong activity against clinical MRSA strains with both MIC50 and MIC90 values lower than 7.8 ng/mL. Compound 27 had good water solubility of 1.98 mg/mL and strong activity against clinical MRSA strains with MIC50 value of 63 ng/mL and MIC90 value of 125 ng/mL, 16-fold higher than that of Vancomycin.

[Analysis of anti-microbial resistance of Escherichia coli that caused infection in urogenital system].

OBJECTIVE: To study the anti-microbial resistance of Escherichia coli (E.coli) that caused infection in urogenital system. METHOD: Anti-microbial susceptibility tests for 148 strains of E.coli were conducted by disc diffusion technique. RESULTS: In 28 commonly used antibiotics, the resistance rates of E. coli to beta-lactam and quinolones were high (73.6%-86.4%). High resistance rates to the first- and the second-generation cephalosporin (cefradime, cephazolin and cefaclor) were also observed (44%). Resistance rate to ceftazidime is the lowest (10.1%) in the third-generation cephalosporin. The resistance rates of E. coli to piperacillin, pefoperazone and ampicillin were 84.5%, 44.6% and 83.0% respectively. Combined antibiotic and beta-lactam inhibitor gave lower resistance rates than antibiotic alone (piperacillin/tazobactam, cefoporazone/sulbactam and ampicillin/sulbactam were 4.1%, 10.8% and 52.0% respectively, P<0.01). Of 148 E. coli isolates, 38 strains were capable of yielding extended-spectrum beta-lactamases (ESBLs) (25.7%), 110 strains were not able to produce ESBLs (74.3%) and the resistance rates of isolates with ESBLs to 28 antibiotics were significantly lower than those of isolates without ESBLs. CONCLUSION: Antibiotic/beta-lactam inhibitor and nitrofurantoin are effective for urogenital infections caused by E. coli.

[Assay of Acinetobacter SPP drug-resistance by Kirby-Bauer and Etest method].

OBJECTIVE: To study the drug-resistance of Acinetobacter spp and observe whether antibiotic-beta- lactamase inhibitor complexing agent enhances the sensitivity of the drug-resistant bacteria to the antibiotics. METHODS: Susceptibility tests to the antibiotics were performed for 60 isolated strains of Acinetobacter spp with Kirby-Bauer (K-B) and Etest methods. RESULTS: The drug-resistance rate of the strains to cefoperazone, ampicillin, ticarcillin and piperacillin exceeded 55.0%, and antibiotic-beta-lactamase inhibitor complexing agents evinced better antibacterial activity than antibiotics used alone (P < 0.001). The 2 antibiotic complexes incorporating sulbacta had more potent antibacterial activity than the complexes incorporating clavulanate (2 agents) and tazobactam (1 agent), with the mean ranks of 7.38, 6.43, 5.57, 5.47 and 5.50 respectively. Cefoperazone combined with sulbacta produced a reduction in MIC(90) and MIC(50) that were only 4.69% and 0.59% of the MIC(50) of cefoperazone, and in addition, sulbacta caused cefoperazone- and ampicillin-resistant rates to reduce from both 75.0% to 5.0% and 24.0%, respectively. CONCLUSION: Acinetobacter spp is resistant to a wide spectrum of commonly-used antibiotics, but cefoperazone in combination with sulbacta can obviously enhance antibacterial potency, suggesting the primary role of this regimen in fighting Acinetobacter spp infections in hospital.

Comparative analysis of standardized and non-standardized of myopia prevalence in Beijing students / 中国学校卫生

Objective@#To clarify the importance and practical significance of the standardized rate in primary healthcare work by comparing the differences in the prevalence of myopia in districts in Beijing before and after standardization.@*Methods@#This study recruited a total of 41 029 students from 107 primary and secondary schools and 35 kindergartens from the 16 districts of Beijing municipality. All participants underwent distance vision and refractive testing. The presence of myopia was defined as naked eye vision of <5.0 and non-ciliary muscle paralysis under computer optometry with a spherical equivalent objective refractive error of <-0.50 diopters (<-0.50 D). The student composition outlined in the 2018-2019 Beijing Education Development Statistics Summary was used as a standard group to standardize the prevalence of myopia in students from various districts of Beijing. The difference in the pre-and post-standardization rates was used to compare the change in myopia in each district before and after standardization.@*Results@#In 2018, the prevalence of myopia in students from Beijing was 57.3%. Stratified by school period, the prevalence of myopia in preschool, primary school, junior high school, ordinary high school, and vocational high school students was 12.1%, 38.4%, 77.2%, 88.3%, and 73.1%, respectively. Although the prevalence of myopia in Daxing District was the highest both before and after standardization, the difference in the prevalence rate was 13.8 percentage points. The prevalence of myopia in Miyun District was the lowest before standardization. However, after standardization, the prevalence of myopia was lowest in Huairou District.@*Conclusion@#The prevalence of myopia among Beijing students is generally high. Before and after standardization, the prevalence of myopia in different districts was quite different. The results show that, in practice, the standardized prevalence can reveal the true epidemiological characteristics of specific disease.

Synthesis, antimicrobial activity and possible mechanism of action of 9-bromo-substituted indolizinoquinoline-5,12-dione derivatives.

A series of 9-bromo-substituted indolizinoquinoline-5,12-dione derivatives was synthesized. Antimicrobial activity assessment indicates that compounds 1, 26, 27 and 28 exhibit strong activity against gram-positive bacterial strains, including Beta-hemolytic streptococcus CMCC32210, Staphylococcus aureus ATCC25923, Staphylococcus epidermidis ATCC12228, Enterococcus faecalis ATCC29212 and methicillin-resistant S. aureus ATCC43300 (MRSA). Compound 27 shows the best anti-MRSA activity with an MIC value of 0.031 µg/ml. To assess the mechanism of action, the inhibitory activities of compound 1 against DNA gyrase and DNA topoisomerase IV were also measured. The results indicate that compound 1 has strong inhibitory effects on the Escherichia coli DNA gyrase supercoiling activity and S. aureus Topo IV relaxing activity.

[Clinical significance of virulence-related genes of type III secretion system of Pseudomonas aeruginosa].

OBJECTIVE: To study the clinical significance of virulence genes exo U and exo S of type III secretion system (TTSS) of Pseudomonas aeruginosa (PA). METHODS: One hundred and eighty-nine clinical isolates of PA were collected from five hospitals. The incidence of virulence genes exo U and exo S in PA were determined with PCR. Minimum inhibitory concentration of anti-bacterial drug for PA was determined with microdilution method. The clinical features and outcomes of 60 hospitalized patients colonized or infected with exo U+/exo S- positive or exo U-/exo S+ positive PA isolated from sputum were analyzed retrospectively. Data were processed with chi-square test. RESULTS: Among the 189 PA isolates, 85.2% (161/189) harbored TTSS genes, including exo U-/exo S+ type (120 isolates), exo U+/exo S- type (31 isolates), exo U-/exo S- type (7 isolates), and exo U+/exo S+ type (3 isolates). 72.0% (72/100) isolates from sputum and 81.5% (44/54) isolates from blood belonged to exo U-/exo S+ genotype. Compared with those of TTSS-negative isolates, the antimicrobial resistance of TTSS-positive isolates to cefoperazone/sulbactam, ceftazidime, amikacin, and cefepime were lower (with χ² value respectively 10.1, 16.1, 9.3, 33.8, P values all below 0.01). The antimicrobial resistance to all examined drug between exo U-/exo S+ type and exo U+/exo S- type isolates was close (with χ² values from 0.08 to 2.04, P values all above 0.05). Patients detected with exo U+/exo S- positive PA isolated from sputum were significantly associated with PA infection, and they usually had history of tracheal intubation, ICU hospitalization, and combined use of drugs for anti-infection treatment. Patients detected with exo U-/exo S+ positive PA isolated from sputum were significantly associated with PA colonization, which had basic lung disease and better outcome than the former infection type. CONCLUSIONS: The TTSS exists in most clinical isolates of PA. Detection of exo U or exo S of PA isolated from sputum is helpful for the analysis of clinical features and outcome of patients.

[Clinical evaluation of the application of gene chip for identifying pathogens in blood cultures].

OBJECTIVE: To explore the feasibility of using gene chip method to identify pathogens in blood cultures. METHODS: Clinical blood samples were obtained and cultured using an automated blood culture system. A gene chip diagnostic kit was used to detect the pathogenic bacteria in these blood cultures following the procedures of target gene extraction and amplification, hybridization and result analysis. The conventional method was also used to isolate and identify the bacteria from the clinical blood cultures, and the results of the two methods were compared. RESULTS: In the 86 clinical blood samples, 74 were positive and 12 negative according to the conventional method, while 48 were positive and 38 negative as found by the gene chip method, showing significant differences in the results (P<0.05). The two methods only had a concordance rate of 69.77%. CONCLUSION: The gene chip diagnostic kit has low concordance rate with the conventional method for detecting pathogens in clinical blood cultures and awaits further improvement.