Stable microbial community diversity across large-scale Antarctic water masses.

The distinctive environmental attributes of the Southern Ocean underscore the indispensability of microorganisms in this region. We analyzed 208 samples obtained from four separate layers (Surface, Deep Chlorophyll Maximum, Middle, and Bottom) in the neighboring seas of the Antarctic Peninsula and the Cosmonaut Sea to explore variations in microbial composition, interactions and community assembly processes. The results demonstrated noteworthy distinctions in alpha and beta diversity across diverse communities, with the increase in water depth, a gradual rise in community diversity was observed. In particular, the co-occurrence network analysis exposed pronounced microbial interactions within the same water mass, which are notably stronger than those observed between different water masses. Co-occurrence network complexity was higher in the surface water mass than in the bottom water mass. Yet, the surface water mass exhibited greater network stability. Moreover, in the phylogenetic-based ß-nearest taxon distance analyses, deterministic processes were identified as the primary factors influencing community assembly in Antarctic microorganisms. This study contributes to exploring diversity and assembly processes under the complex hydrological conditions of Antarctica.

Distinct structure, assembly, and gene expression of microplankton in two Arctic estuaries with varied terrestrial inputs.

The Laptev Sea is a major Marginal Sea in the Western Arctic Ocean. The Arctic amplification brought by global warming influences the hydrological properties of rivers passing through the permafrost zone, which would alter the biological community structure at continental margin. In this study, the structure, assembly, and gene expression of planktonic microbial communities in two estuaries (Protoka Ularovskaya River Estuary, PURE; Lena River Estuary, LRE) of Laptev Sea were examined to investigate the environmental effects of polar rivers. PURE and LRE exhibited distinct environmental characteristics: low temperature and high salinity for PURE, and high temperature and low salinity for LRE, influenced by runoff size. Salinity more closely influenced microbial communities in LRE, with freshwater species playing a significant role in community composition. The findings revealed differences between two estuaries in community composition and diversity. Prokaryotes and microeukaryotes had shown different assembly patterns in response to habitat changes caused by terrestrial freshwater input. Furthermore, compared with the PURE, the co-occurrence and inter-domain network of the LRE, which was more affected by terrestrial input, was more complex and stable. Functional gene prediction revealed a higher gene expression of methane metabolism in LRE than in PURE, particularly those related to methane oxidation, and this conclusion could help better explore the impact of global warming on the methane cycle in the Arctic Marginal Seas. This study explored the increased freshwater runoffs under the background of global warming dramatically affect Arctic microplankton communities from community structure, assembly and gene expression aspects.

Microbial community structure and co-occurrence network stability in seawater and microplastic biofilms under prometryn pollution in marine ecosystems.

Prometryn has been extensively detected in marine environment because of its widespread usage in agriculture and aquaculture and has been concerns since its serious effects on aquatic organisms. However, its impact on the microbial community in the marine ecosystem including seawater and biofilm is still unclear. Therefore, a short-term indoor microcosm experiment of prometryn exposure was conducted. This study found that prometryn had a more significant impact on the structure and stability of the microbial community in seawater compared to microplastic biofilms. Additionally, we observed that the assembly of the microbial community in biofilms was more affected by stochastic processes than in seawater under the exposure of prometryn. Our study provided evidence for the increasing impact of the microbial communities under the stress of prometryn and microplastics.

The co-presence of polystyrene nanoplastics and ofloxacin demonstrates combined effects on the structure, assembly, and metabolic activities of marine microbial community.

Nanoplastic is increasing in environments and can address toxic effects on various organisms. Particle size, concentration, and surface functionalization most influence nanoplastic toxicity. Besides, nanoplastic can adsorb other contaminants (e.g., antibiotics) to aggravate its adverse effects. The combined effects of nanoplastics and antibiotics on planktonic/benthic microbial communities, however, are still largely unknown. In this study, the combined effects of polystyrene nanoplastic and ofloxacin on the structure, assembly, and metabolic activities of marine microbial communities were investigated based on amplicon sequencing data. The results mainly demonstrate that: (1) nanoplastic and ofloxacin have greater impacts on prokaryotic communities than eukaryotic ones; (2) niche breadths of planktonic prokaryotes and benthic eukaryotes were shrank with both high nanoplastic and ofloxacin concentrations; (3) increased ofloxacin mainly reduces nodes/edges of co-occurrence networks, while nanoplastic centralizes network modularity; (4) increased nanoplastic under high ofloxacin concentration induces more differential prokaryotic pathways in planktonic communities, while benthic communities are less influenced. The present work indicates that co-presence of nanoplastics and ofloxacin has synergistic combined effects on community structure shifts, niche breadth shrinking, network simplifying, and differential prokaryotic pathways inducing in marine microbial communities, suggesting nanoplastics and its combined impacts with other pollutions should be paid with more concerns.

Room Temperature Strengthening and High-Temperature Superplasticity of Mg-Li-Al-Sr-Y Alloy Fabricated by Asymmetric Rolling and Friction Stir Processing.

Magnesium-lithium alloy is the lightest alloy to date. To explore its room temperature strength and high-temperature ductility, a plate of a new fine-grained Mg-9.13Li-3.74Al-0.31Sr-0.11Y alloy was fabricated by asymmetric rolling, and the rolled plate was subjected to friction stir processing (FSP). The microstructure and mechanical properties at room and elevated temperatures were investigated by optical microscopy, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and tensile tester. Grain refinement with an average grain size in the α-Mg phase of 1.65 µm and an average grain size in the ß-Li phase of 4.24 µm was achieved in the water-cooled FSP alloy. For room temperature behavior, the ultimate tensile strength of 208 ± 4 MPa, yield strength of 193 ± 2 MPa, and elongation of 48.2% were obtained in the water-cooled FSP alloy. XRD and EDS analyses revealed that the present alloy consists of α-Mg and ß-Li phases, Al2Y, Al4Sr, MgLi2Al, and AlLi intermetallic compounds. For high-temperature behavior, the maximum superplasticity or ductility of 416% was demonstrated in this fine-grained alloy with an average grain size of 10 µm at 573 K and 1.67 × 10-3 s-1. A power-law constitutive equation was established. The stress exponent was 2.29 (≈2) (strain rate sensitivity 0.44), and the deformation activation energy was 162.02 kJ/mol. This evidence confirmed that the dominant deformation mechanism at elevated temperatures is grain boundary and interphase boundary sliding controlled by lattice diffusion.

Room-Temperature Strengthening, Portevin-Le Chatelier Effect, High-Temperature Tensile Deformation Behavior, and Constitutive Modeling in a Lightweight Mg-Gd-Al-Zn Alloy.

To explore room-temperature strengthening and high-temperature ductility, a lightweight novel Mg-1.85Gd-0.64Al-0.62Zn alloy was fabricated by innovative multidirectional forging and a hot-rolling technique. Microstructures and mechanical properties were studied at room and elevated temperatures with an optical microscope, an X-ray diffractometer, and a tensile tester. An ultimate tensile strength of 260 MPa, yield strength of 171 MPa, and elongation of 20.4% were demonstrated at room temperature. The room-temperature strengthening mechanisms were identified by strengthening the model estimation. A type C Portevin-Le Chatelier effect was discovered and elucidated in this alloy. X-ray diffraction analysis revealed that the phase composition is α-Mg solid solution and (Mg, Al)3Gd, Al7Zn3, and Al2Gd intermetallic compounds. Examination of the microstructure at elevated temperatures revealed that dynamic recrystallization and dynamic grain growth occur. In particular, it was discovered that bimodal microstructures or incomplete dynamic recrystallization microstructures exist in high-temperature deformation. A maximum quasi-superplasticity of 228.4% was demonstrated in this alloy at 673 K and 5.0 × 10-4 s-1. Flow stress curves showed that the present alloy exhibits Sotoudeh-Bate curves or a long intermediate strain-hardening stage followed by a strain-softening stage. A modified Zerilli-Armstrong constitutive equation incorporating the number of dislocations was established. The power-law constitutive equation was established to identify the deformation mechanism. Both constitutive models had good predictability. At 673 K and 5.0 × 10-4 s-1, the stress exponent was 4, and the average deformation activation energy was 104.42 kJ/mol. The number of dislocations inside a grain was 146. This characteristic evidence confirmed that dislocation motion controlled by pipe diffusion dominates the rate-controlling process under this condition.

High Strain Rate Quasi-Superplasticity Behavior in an Ultralight Mg-9.55Li-2.92Al-0.027Y-0.026Mn Alloy Fabricated by Multidirectional Forging and Asymmetrical Rolling.

To explore new approaches to severe plastic deformation and the ductility of a multicomponent magnesium-lithium alloy, an ultralight microduplex Mg-9.55Li-2.92Al-0.027Y-0.026Mn alloy was made by novel multidirectional forging and asymmetrical rolling, and the superplasticity behavior was investigated by optical microscope, hot tensile test, and modeling. The average grain size is 1.9 µm in this alloy after multidirectional forging and asymmetrical rolling. Remarkable grain refinement caused by such a forming, which turns the as-cast grain size of 144.68 µm into the as-rolled grain size of 1.9 µm, is achieved. The elongation to failure of 228.05% is obtained at 523 K and 1 × 10-2 s-1, which demonstrates the high strain rate quasi-superplasticity. The maximum elongation to failure of 287.12% was achieved in this alloy at 573 K and 5 × 10-4 s-1. It was found that strain-induced grain coarsening at 523 K is much weaker than the strain-induced grain coarsening at 573 K. Thus, the ductility of 228.05% is suitable for application in high strain rate superplastic forming. The stress exponent of 3 and the average activation energy for deformation of 50.06 kJ/mol indicate that the rate-controlling deformation mechanism is dislocation-glide controlled by pipe diffusion.

Bimetallic aluminum complexes bearing novel spiro-phenanthrene-monoketone/OH derivatives: synthesis, characterization and the ring-opening polymerization of ε-caprolactone.

A series of spiro-phenanthrene-monoketone/OH derivatives (L1-L6) were synthesized and fully characterized with 1H/13C NMR spectroscopy and elemental analyses. By treating ligands with AlMe3, oxygen-bridged binuclear aluminum complexes (Al1-Al6) were isolated and characterized by 1H/13C NMR spectroscopy. The molecular structures of ligands (L2, L4 and L5) and complex Al1 were determined by single crystal X-ray diffraction. In the presence of benzyl alcohol (BnOH), these aluminum complexes demonstrated high efficiency towards the ring-opening polymerization of ε-caprolactone (ε-CL), resulting in PCL in a linear manner with the BnO-end group. In addition, complexes Al1 and Al5 exhibited good catalytic activities even without BnOH. Moreover, complexes Al3 and Al6 with the bulkier substituent of iPr at the ortho-position of the arylamines demonstrated better catalytic activities than the analogs. Moreover, substituents on the backbone also affected catalytic behaviors.

Efficacy and safety of telbivudine and tenofovir disoproxil fumarate in preventing hepatitis B vertical transmission: A real-life practice.

Mother-to-child transmission (MTCT) is a major obstacle in the elimination of hepatitis B virus (HBV) infection. Telbivudine (LdT) and tenofovir disoproxil fumarate (TDF) are the two most common antiviral medicines for preventing MTCT. However, the efficacy and safety of LdT and TDF in preventing HBV vertical transmission during the second to third trimester have not been compared rigorously. Therefore, we carried out a prospective multicentre cohort study of chronic hepatitis B in mothers with HBV DNA > 106  IU/mL, receiving LdT or TDF during the second to third trimester. Among the 893 mothers enrolled, 857 (LdT/TDF/untreated group (NTx) = 396/325/136) completed consecutive follow-up with 854 infants (LdT/TDF/NTx = 395/323/136). LdT and TDF treatment resulted in a similar decrease of HBV DNA in mothers at delivery. Multivariate analysis indicated that only HBsAg titre at the baseline correlated with viral DNA decrease (P = 0.015). With intention-to-treat analysis, MTCT rates in the LdT, TDF and NTx group were 4.41%, 2.42% and 22.08%, respectively. An increasing vertical transmission rate was found to be closely associated with higher HBsAg titre, 5.32% and 17.65% infection rate was estimated in infants born to mothers with HBsAg > 4 and >5 log10 IU/mL, respectively. No serious side effects were reported in either mothers or infants. LdT and TDF treatments were well tolerated and showed comparable efficacy in reducing MTCT. Higher risk of MTCT was shown in pregnant women with HBsAg > 4 log10 IU/mL.

Different interventional criteria for chronic hepatitis B pregnant women with HBeAg(+) or HBeAg(-): Epidemiological data from Shaanxi, China.

The seroprevalence of hepatitis B virus (HBV) and its impact on pregnancy outcomes of women from Shaanxi Province (China) was assessed. Risk factors for mother-to-child transmission (MTCT) were evaluated based on HBV-related seroprevalence data.Viral markers and biochemical parameters were assessed in HBsAg-positive mothers and their infants out of 13,451 cases recruited. A pretested and structured questionnaire was used to test the general HBV knowledge. Descriptive statistics and logistic regression analysis were done to reveal possible risk factors for MTCT.The overall prevalence of HBsAg in pregnant women was 7.07% (951/13,451), and a rate as high as 9.40% was observed. Among the HBsAg-positive pregnant women, 30.49% (290/951) were HBeAg-positive, 22.08% (210/951) had HBV DNA levels >10 IU/mL and only 16.19% with a high risk of MTCT (34/210) had received antiviral treatment. The overall MTCT rate was 5.21%. Noteworthy, the risk ratio and 95% confidence interval (95% CI) of MTCT in HBeAg-negative mothers with HBV DNA levels >2 × 10 IU/mL and HBsAg >10 IU/mL was 26.062 (2.633-258.024), which was significantly higher than that of HBeAg-positive mothers with HBV DNA level >10 IU/mL. Moreover, the awareness and knowledge about HBV transmission, risk factors, and intervention for MTCT were generally lacking among HBsAg-positive mothers.As a higher HBsAg seroprevalence and a higher MTCT rate among HBeAg-negative mothers with lower HBV DNA level was observed, our study emphasizes different interventional criteria for HBeAg-positive and HBeAg-negative mothers. Extensive health education, routine screening, and immunization against HBV during pregnancy are highly warranted to minimize the possibility of perinatal transmission.

Baseline Hepatitis B Virus Titer Predicts Initial Postpartum Hepatic Flare: A Multicenter Prospective Study.

BACKGROUND AND GOALS: A series of changes in the immune system occur during pregnancy and puerperium. Currently, we aim to characterize both the natural changes in liver inflammation and its association with hepatitis B viremia during this special period. PATIENTS AND METHODS: Chronic hepatitis B (CHB) gravidas were recruited and followed up to 52 weeks postpartum. Virological and biochemical parameters were assessed throughout the period. RESULTS: A total of 1097 CHB mothers had finished the entire follow-up including 451 accepting telbivudine, 178 accepting tenofovir, and 468 without antiviral therapy. Among the mothers, 11.94% went through hepatic flare in the first trimester and the rate decreased to 2.1% at the time of delivery. Nevertheless, a much higher frequency (19.78%) was observed in the early postpartum. Interestingly, alanine aminotransferase level decreased along with the development of pregnancy and then suddenly increased in the first month of puerperium. In addition, a downward trend was observed on the titer of HBsAg and HBeAg after delivery. Of note, an obvious higher frequency of alanine aminotransferase flare was revealed in mothers with high viremia (>6 log10 IU/mL). With multivariate analysis, only hepatitis B virus titer at baseline was strongly associated with hepatic flare during early postpartum (95% confidence interval, 1.012-3.049, P=0.045). The predictive rates of hepatic flare at baseline viral load of 6, 7, and 8 log10 IU/mL were 16.67%, 28.30%, and 30.60%, respectively. CONCLUSIONS: CHB gravidas with high viremia should be monitored closely during entire pregnancy, and extended antiviral therapy is recommend to those mothers with baseline viremia >7 log10 IU/mL.

Hepatic flare after telbivudine withdrawal and efficacy of postpartum antiviral therapy for pregnancies with chronic hepatitis B virus.

BACKGROUND AND AIM: The efficacy of telbivudine for breaking vertical transmission of hepatitis B virus has been well established. Data on the risk of postpartum flare after telbivudine withdrawal and efficacy of extended antiviral therapy after delivery are limited. METHODS: Chronic hepatitis B virus-infected women who received telbivudine beginning at week 24 or 28 of gestation were enrolled and then followed up to 52 weeks postpartum. Virological and biochemical parameters were assessed. RESULTS: Of the 241 women who finished 52 weeks of follow-up, 33.6% had elevated serum alanine aminotransferase (ALT) during pregnancy. Telbivudine administration resulted in ALT normalization in 85.2% before delivery. Compared with women having a normal ALT level throughout pregnancy, those with elevated ALT had a significantly higher rate of ALT flare after telbivudine withdrawal (25.0% vs 11.9%; χ2 = 4.273, P = 0.039). Multivariate analysis indicated that only ALT elevation during pregnancy correlated with postpartum flare after telbivudine withdrawal. Those women with elevated ALT during pregnancy continued antiviral treatment to 52 weeks postpartum and had a significantly higher HBeAg seroconversion rate (P = 0.001) and a notable decrease in HBsAg titers (P = 0.001). CONCLUSION: It is safe for the majority of women to withdraw telbivudine after delivery, whereas exciting serological response encourages extended antiviral therapy for mother with ALT elevation during pregnancy.

Efficacy of tenofovir disoproxil fumarate to prevent vertical transmission in mothers with lamivudine-resistant HBV.

BACKGROUND: In China, women with chronic HBV infection and who are of childbearing age receive lamivudine at an early age. Thus, viral resistance becomes a challenge for intervention to prevent mother-to-infant transmission. We prospectively assessed the efficacy of tenofovir in pregnant women with lamivudine-resistant HBV. METHODS: Chronic HBV-infected mothers resistant to lamivudine were enrolled. Tenofovir was administrated at gestation weeks 24 or 28. Virological and biochemical parameters were assessed. All infants received combined immunoprophylaxis and were followed for 1 year. RESULTS: Of the 48 mothers enrolled, 21 started tenofovir therapy at gestation week 24 and 27 started at week 28. Tenofovir resulted in an HBV DNA decline of 5.23 ± 1.68 log10 IU/ml at delivery. The group starting therapy at week 24 exhibited a more rapid viral inhibition (P<0.001) and more significant HBV DNA load decline (5.89 ± 1.66 versus 4.72 ± 1.55; P=0.019) than the group starting at week 28. At delivery, all mothers had a viral titre <10(6) IU/ml, 76.2% from the week 24 starting group displayed virus <10(4) IU/ml, and 52.4% showed undetectable virus at delivery, much higher than the week 28 starting group (29.6%), although there was no statistically significant difference in viral levels at delivery between the two groups. Congenital abnormalities and neonatal growth were comparable to the normal population. No case of perinatal transmission was diagnosed. CONCLUSIONS: This investigation clarifies the efficacy of tenofovir for reducing vertical transmission of HBV in mothers with lamivudine-resistant HBV and demonstrates that tenofovir is well-tolerated in the second and third trimesters.

[Surveillance of schistosomiasis in Yanjiang Village, Hanjiang District, 2005-2010].

The endemic situation of schistosomiasis and Oncomelania snail status in Yanjiang Village, Hanjiang District decreased significantly from 2005 to 2010. However, the surveillance in key population such as fishmen and boatmen still needs to be strengthened.