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1,3,5-tris（3,3,3-trifluoropyl）-1,3,5-trimethylcyclotrisiloxane （D3F） and hexamethylcyclotrisiloxane were used as raw materials to synthesize fluorosilicone copolymer with high molecular weight. The effects of reaction time and reaction temperature on molecular weight of the products and monomer ratio on chain segment content of the copolymers were studied. The structure of the copolymer was characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy, and its molecular weight was determined by Ubbelohde viscometer. The results showed that the proportion of chain segment content in fluorosilicone rubber was closer to that of feed when D3F amount was high. With increase of reaction temperature and time, molecular weight of the fluorosilicone copolymer first increased and then decreased. Molecular weight of fluorosilicone copolymer could be effectively increased by stopping heating at an approp-riate node in the reaction process. When the reaction temperature was 90 ℃, reaction time was 10 min and mole fraction of D3F was 80%, molecular weight of fluorosilicone copolymer reached the maximum, and the viscosity average molecular weight was 8.2×105.

Three novel ent-kaurane diterpenes, namely sigesbeckin A–C (1–3), in conjunction with eight previously identified analogues (4–11), were isolated from Sigesbeckia orientalis. Their chemical structures were resolved through multiple spectroscopic analyses. All compounds were assessed for antimicrobial bioactivity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) strains. In particular, compounds 1 and 5 demonstrated moderate efficacy, with MIC values of 64 μg/mL. Moreover, compounds 3, 5, and 11 were found to synergize with doxorubicin hydrochloride (DOX) and vancomycin (VAN) against MRSA and VRE. The aforementioned findings offer valuable insights for the development of novel alternatives to antibiotics, which can effectively tackle the escalating issue of antibiotic resistance. [ABSTRACT FROM AUTHOR]

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, characterized by social communication disability and stereotypic behavior. This study aims to investigate the impact of prenatal exposure to 1‐nitropyrene (1‐NP), a key component of motor vehicle exhaust, on autism‐like behaviors in a mouse model. Three‐chamber test finds that prenatal 1‐NP exposure causes autism‐like behaviors during the weaning period. Patch clamp shows that inhibitory synaptic transmission is reduced in medial prefrontal cortex of 1‐NP‐exposed weaning pups. Immunofluorescence finds that prenatal 1‐NP exposure reduces the number of prefrontal glutamate decarboxylase 67 (GAD67) positive interneurons in fetuses and weaning pups. Moreover, prenatal 1‐NP exposure retards tangential migration of GAD67‐positive interneurons and downregulates interneuron migration‐related genes, such as Nrg1, Erbb4, and Sema3F, in fetal forebrain. Mechanistically, prenatal 1‐NP exposure reduces hydroxymethylation of interneuron migration‐related genes through inhibiting ten‐eleven translocation (TET) activity in fetal forebrain. Supplement with alpha‐ketoglutarate (α‐KG), a cofactor of TET enzyme, reverses 1‐NP‐induced hypohydroxymethylation at specific sites of interneuron migration‐related genes. Moreover, α‐KG supplement alleviates 1‐NP‐induced migration retardation of interneurons in fetal forebrain. Finally, maternal α‐KG supplement improves 1‐NP‐induced autism‐like behaviors in weaning offspring. In conclusion, prenatal 1‐NP exposure causes autism‐like behavior partially by altering DNA hydroxymethylation of interneuron migration‐related genes in developing brain. [ABSTRACT FROM AUTHOR]

Background: Anxiety and depression can influence adherence to Pre-exposure Prophylaxis (PrEP). However, there is limited research on the temporal dynamics of anxiety and depression among men who have sex with men (MSM) using PrEP. Methods: From December 2018 to November 2020, we administered the Hospital Anxiety and Depression Scale (HADS) to participants in the China Real-World Oral Intake of PrEP (CROPrEP) to measure their anxiety and depression levels. The group-based trajectory model (GBTM) depicted the dynamic changes of anxiety and depression scores over time. Results: A total of 1023 MSM were included, with 4523 follow-up assessments. The GBTM categorized the trajectories into three distinct patterns: consistently low (54.8% for anxiety, 60.7% for depression), consistently moderate (39.3% for anxiety, 31.4% for depression), and high but bell-shaped (5.9% for anxiety, 7.9% for depression). Higher anxiety levels were associated with being aged 18–30 years old, earning less than US$619 per month, female-identifying, adopting the bottom sexual role with men, and having two or more anal sex partners in the past three months; similarly, higher depression levels correlated with a monthly income under US$619, female-identifying, sexual behavior as bottom and a positive syphilis at baseline. PrEP adherence was notably lower in the high but bell-shaped anxiety and depression group compared to the other groups, particularly at the 12th-month follow-up. Conclusions: Close monitoring of anxiety and depression levels in MSM on PrEP is crucial. Provision of targeted mental health support is essential to enhance PrEP effectiveness. [ABSTRACT FROM AUTHOR]

Monoterpene indole alkaloids exhibit structural diversity in herbal resources and have been developed as promising drugs owing to their significant biological activities. Confidential identification and quantification of monoterpene indole alkaloids is the key to quality control of target plants in industrial production but has rarely been reported. In this study, quantitative performance of three data acquisition modes of ultra‐high‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry including full scan, auto‐MS2 and target‐MS2, was evaluated and compared for specificity, sensitivity, linearity, precision, accuracy, and matrix effect using five monoterpene indole alkaloids (scholaricine, 19‐epi‐scholaricine, vallesamine, picrinine, and picralinal). Method validations indicated that target‐MS2 mode showed predominant performance for simultaneous annotation and quantification of analytes, and was then applied to determine monoterpene indole alkaloids in Alstonia scholaris (leaves, barks) after extraction procedures optimization using Box‐Behnken design of response surface methodology. The variations of A. scholaris monoterpene indole alkaloids in different plant parts, harvest periods, and post‐handling processes, were subsequently investigated. The results indicated that target‐MS2 mode could improve the quantitative capability of ultra‐high‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry for structure‐complex monoterpene indole alkaloids in herbal matrices. Alstonia scholaris, monoterpene indole alkaloids, quadrupole time of flight mass spectrometry, qualitative and quantitative analysis, ultra‐high‐performance liquid chromatography [ABSTRACT FROM AUTHOR]