Overload of dissolved organic matter (DOM) in riparian infiltration zone increasing the pollution risk of naphthalene, insight from the competitive inhibition of naphthalene biodegradation by DOM.

Riparian infiltration zones are crucial for maintaining water quality by reducing the aqueous concentrations of polycyclic aromatic hydrocarbons (PAHs) through adsorption and biodegradation within the aquatic ecosystem. Dissolved organic matter (DOM) are ubiquitous in riparian infiltration zones where they extensively engage in the adsorption and biodegradation of PAHs, thereby influencing PAHs natural attenuation potential within riparian infiltration zones. Few studies have explored the natural attenuation mechanisms of PAHs influenced by DOM in riparian infiltration zones. In this study, the natural attenuation mechanisms of naphthalene (a typical PAHs component), under the influence of DOM, were explored, based on a case riverside source area. Analysis of microbial community structures, and the electron acceptor (e.g., Fe(III), DO/NO3-, SO42-)/electron donor (naphthalene and DOM) concentration changes within the riparian infiltration zone revealed a competitive inhibition relationship between DOM and naphthalene during microbial metabolism. Biodegradation experiments showed that when the concentration of DOM is higher than 4.0 mg·L-1, it inhibits the biodegradation of naphthalene. DOM competitively inhibits the biodegradation of naphthalene through the following mechanisms: (i) triggering microbial antioxidative defense mechanisms, diminishing the available resources for microbial participation in naphthalene degradation; (ii) altering microbial community structure; (iii) modulating microbial EPS composition, reducing the efficiency of microorganisms in utilizing carbon sources; and (iv) inhibiting the expression levels of downstream genes involved in naphthalene degradation. The competitive inhibition constants of DOM with concentrations of 1.0, 2.0, 4.0, 8.0, and 16.0 mg·L-1 on naphthalene biodegradation are -2.0 × 10-3, -5.0 × 10-3,1.0 × 10-3, 4.0 × 10-4, and 1.0 × 10-4, respectively. These findings enhance understanding of PAHs attenuation in riparian infiltration zone, providing a basis for assessing and managing PAHs pollution risks during riparian extraction.

Incidence and spontaneous clearance of gonorrhea and chlamydia infections among men who have sex with men: a prospective cohort study in Zhuhai, China.

Background: Men who have sex with men (MSM) face significant risks of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) infection. Nevertheless, only limited studies have looked into the site-specific infection and clearance of CT/NG. In order to prevent transmission, it is essential to understand the underlying factors that drive infection and spontaneous clearance. Methods: A 12-week cohort study examined the association between CT/NG infection, self-clearance, and sexual behaviors among MSM. The Willingness Service recruited participants who completed weekly questionnaires and provided urine, throat, and rectal swab samples. Results: The study involved 151 men, in which 51 (33.8%) were diagnosed with CT/NG infection during the study period. HIV (OR = 11.31), kissing (OR = 1.59), receptive oral sex (OR = 36.64), and insertive anal sex (OR = 19.73) constituted significant risk factors. 100% condom use (OR = 5.78) and antibiotic (OR = 7.53) were more likely to cause spontaneous clearance. Discussion: MSM may engage in riskier sexual behaviors due to insufficient knowledge and awareness of STI prevention, leading to increased susceptibility to NG/CT. It is crucial to concentrate on enhancing health education for MSM. Conclusion: This study found that the rectum was the most prevalent site of CT/NG and sexual behavior can influence the infection. Additionally, the appropriate use of antibiotics and consistent condom use may contribute to clear spontaneously.

Nitrate denitrification rate response to temperature gradient change during river bank infiltration.

Nitrate attenuation during river bank infiltration is the key process for reducing nitrogen pollution. Temperature is considered to be an important factor affecting nitrate attenuation. However, the magnitude and mechanism of its impact have not been clear for a long time. In this study, the effects of temperature and temperature gradient on the nitrate denitrification rate were investigated via static batch and dynamic soil column simulation experiments. The results showed that temperature had a significant effect on the denitrification rate. Temperature effects were first observed in denitrifying bacteria. At low temperatures, the microorganism diversity was low, resulting in a lower denitrification rate constant. The static experimental results showed that the denitrification rate at 19 °C was approximately 2.4 times that at 10 °C. The dynamic soil column experiment established an exponential positive correlation between the nitrate denitrification decay kinetic constant and temperature. The affinity of denitrifying enzymes for nitrate in the reaction substrate was ordered as follows: decreasing temperature gradient (30 °C → 10 °C) > zero temperature gradient (10 °C) > increasing temperature gradient condition (0 °C → 10 °C). This study provides a theoretical basis for the biogeochemical processes underlying river bank infiltration, which will help aid in the development and utilization of groundwater resources.

Two-Stage Dynamic Transformation from δ- to α-CsPbI3.

The phase transformation from δ- to α-CsPbI3has garnered extensive research interest. However, detailed understanding of this structural transformation at atomistic scale remains elusive. Here, we reported the full atomistic molecular dynamics simulation of this important phase transformation using an enhanced sampling method, Metadynamics (MetaD). Particularly, two-stage of dynamic transformation related to [PbI3]- chains' motions was observed, namely, the intrachain rearrangement followed by interchain connection. Moreover, the dynamic motion of Cs+ cations plays an important role in facilitating the interchain connection kinetically. The insights reported in this work will provide valuable guidance for further advancing the understanding of phase transformation of CsPbI3.

Factors Associated with the First-time HIV Testing Among Chinese men who have sex with men Who Received HIV Self-tests from Partners or Friends.

Secondary distribution of HIV self-testing (HIVST) among individual social networks was an effective approach to expanding HIV testing among men who have sex with men (MSM). However, understanding the factors associated with first-time HIV testing behaviors in the secondary distribution of HIVST programs is limited. Hence, this study aims to identify factors related to first-time testers in the secondary distribution of HIVST. Participants were recruited from five provinces in southern China through Blued, a geo-social gay networking app in China from January 2021 to December 2021. Eligible consented participants (referred to as "seeds") finished a baseline survey and then applied for up to five HIVST kits. They were encouraged to distribute HIVST kits to other MSM (referred to as "alters") and alters were encouraged to scan a QR code to return their photographed testing results. All alters were invited to finish an online survey. In total, 229 seeds reached 292 alters, among whom 126 (43.2%) were first-time testers whereas 166 (56.8%) were non-first-time testers. Importantly, our results demonstrated that the first-time HIV testers were more likely to self-report as heterosexual (aOR = 4.88, 95% CI 1.01-23.61), disclose sexual orientation and/or SSB (aOR = 1.73, 95% CI 1.01-2.96), and receive HIVST knowledge from the seeds (aOR = 3.25, 95% CI 1.02-10.34). However, those who had sex with male partners in the last three months were less likely to be first-time testers (aOR = 0.43, 95% CI 0.23-0.82). Practical implications and limitations were also discussed to improve future HIV prevention programs.

Clinical and electrophysiological features of SCN8A variants causing episodic or chronic ataxia.

BACKGROUND: Variants in SCN8A are associated with a spectrum of epilepsies and neurodevelopmental disorders. Ataxia as a predominant symptom of SCN8A variation has not been well studied. We set out to investigate disease mechanisms and genotype-phenotype correlations of SCN8A-related ataxia. METHODS: We collected genetic and electro-clinical data of ten individuals from nine unrelated families carrying novel SCN8A variants associated with chronic progressive or episodic ataxia. Electrophysiological characterizations of these variants were performed in ND7/23 cells and cultured neurons. FINDINGS: Variants associated with chronic progressive ataxia either decreased Na+ current densities and shifted activation curves towards more depolarized potentials (p.Asn995Asp, p.Lys1498Glu and p.Trp1266Cys) or resulted in a premature stop codon (p.Trp937Ter). Three variants (p.Arg847Gln and biallelic p.Arg191Trp/p.Asp1525Tyr) were associated with episodic ataxia causing loss-of-function by decreasing Na+ current densities or a hyperpolarizing shift of the inactivation curve. Two additional episodic ataxia-associated variants caused mixed gain- and loss-of function effects in ND7/23 cells and were further examined in primary murine hippocampal neuronal cultures. Neuronal firing in excitatory neurons was increased by p.Arg1629His, but decreased by p.Glu1201Lys. Neuronal firing in inhibitory neurons was decreased for both variants. No functional effect was observed for p.Arg1913Trp. In four individuals, treatment with sodium channel blockers exacerbated symptoms. INTERPRETATION: We identified episodic or chronic ataxia as predominant phenotypes caused by variants in SCN8A. Genotype-phenotype correlations revealed a more pronounced loss-of-function effect for variants causing chronic ataxia. Sodium channel blockers should be avoided under these conditions. FUNDING: BMBF, DFG, the Italian Ministry of Health, University of Tuebingen.