Visible-light-mediated metal-free regioselective oxidative C-C bond cleavage of lignin dimers to aromatic acids.

The upgrading of lignin is a sustainable and promising pathway for fossil-based aromatic compounds but always faces low selectivity. Herein, a metal-free photocatalyst, 2,4,6-triphenylpyrylium tetrafluoroborate (TPP), was illustrated to remarkably facilitate the regioselective oxidative Cα-Cß bond cleavage of ß-1 and ß-O-4 lignin alcohol/ketone models into aromatic acids (92-99% yields) under visible-light irradiation at room temperature without any additive/co-catalyst, which was enabled by the synergistic effect of Cß-H⋯C(TPP) interaction and·Ë™O2-/1O2 species. The synergy of the catalyst-substrate interaction and active species offers a reference for the enhancive and selective transformation of polymeric biomass and complex molecules.

Trajectories of antepartum depressive symptoms and birthweight: a multicenter and prospective cohort study.

BACKGROUND: Antepartum depression is a prevalent unhealthy mental health problem worldwide, particularly in low-income countries. It is a major contributor to adverse birth outcomes. Previous studies linking antepartum depression to birthweight have yielded conflicting results, which may be the reason that the depressive symptoms were only measured once during pregnancy. This study aimed to explore the associations between trajectories of antepartum depressive symptoms and birthweight. METHODS: Depressive symptoms were assessed prospectively at each trimester in 3699 pregnant women from 24 hospitals across 15 provinces in China, using the Edinburgh Postpartum Depression Scale (EPDS). Higher scores of EPDS indicated higher levels of depressive symptoms. Associations between trajectories of depressive symptoms and birthweight were examined using group-based trajectory modeling (GBTM), propensity score-based inverse probability of treatment weighting (IPTW), and logistic regression. RESULTS: GBTM identified five trajectories. Compared with the low-stable trajectory of depressive symptoms, only high-stable (OR = 1.35, 95% CI: 1.15-2.52) and moderate-rising (OR = 1.18, 95% CI: 1.12-1.85) had an increased risk of low birthweight (LBW) in the adjusted longitudinal analysis of IPTW. There was no significant increase in the risk of LBW in moderate-stable and high-falling trajectories. However, trajectories of depressive symptoms were not associated with the risk of macrosomia. CONCLUSION: Antepartum depressive symptoms were not constant. Trajectories of depressive symptoms were associated with the risk of LBW. It is important to optimize and implement screening, tracking, and intervention protocols for antepartum depression, especially for high-risk pregnant women, to prevent LBW.

Trajectories of depressive symptoms during pregnancy and risk of premature birth: A multicenter and prospective cohort study.

Previous studies only assessed the association between depressive symptoms and risk of preterm birth (PTB) at a time-point during pregnancy, resulting in inconsistent or contradictory results. Therefore, we aimed to explore the associations between the trajectories of depressive symptoms during pregnancy and risk of PTB. In total, 7732 pregnant women were included in 24 hospitals from 15 provinces of China. The Edinburgh Postpartum Depression Scale (EPDS) was used to evaluate depressive symptoms in the first, second, and third trimesters. Associations between depressive symptoms and risk of PTB were performed by group-based trajectory modeling (GBTM), propensity score-based inverse probability of treatment weighting (IPTW), and logistic regression. GBTM identified five trajectories: compared with persistently low-stable trajectory of depressive symptoms, women with moderate-stable (OR = 1.23, 95% CI: 1.02-1.76), high-falling (OR = 1.35, 95% CI: 1.11-2.21), moderate-rising (OR = 1.38, 95% CI: 1.06-2.04), and high-stable trajectory of depressive symptoms (OR = 1.40, 95% CI: 1.16-3.28) had an increased risk of PTB. In addition, the associations between trajectories of depressive symptoms and risk of PTB were most significant in multiparous women with a history of PTB. There was no difference in the risk of early-moderate PTB among different trajectories of depressive symptoms and only the risk of late PTB was different among different trajectories. In conclusion, the depressive symptoms of pregnant women were not constant during pregnancy, and different trajectories of depressive symptoms were associated with different risks of PTB.

Pre-pregnancy body mass index and risk of maternal or infant complications with gestational diabetes mellitus as a mediator: A multicenter, longitudinal cohort study in China.

AIMS: We explored the complex relationships between pre-pregnancy body mass index (pBMI) and maternal or infant complications and the mediating role of gestational diabetes mellitus (GDM) in these relationships. METHODS: Pregnant women from 24 hospitals in 15 different provinces of China were enrolled in 2017 and followed through 2018. Propensity score-based inverse probability of treatment weighting, logistic regression, restricted cubic spline models, and causal mediation analysis were utilized. In addition, the E-value method was used to evaluate unmeasured confounding factors. RESULTS: A total of 6174 pregnant women were finally included. Compared to women with a normal pBMI, obese women had a higher risk for gestational hypertension (odds ratio [OR] = 5.38, 95% confidence interval [CI]: 3.48-8.34), macrosomia (OR = 2.65, 95% CI: 1.83-3.84), and large for gestational age (OR = 2.05, 95% CI: 1.45-2.88); 4.73% (95% CI: 0.57%-8.88%), 4.61% (95% CI: 0.51%-9.74%), and 5.02% (95% CI: 0.13%-10.18%) of the associations, respectively, were mediated by GDM. Underweight women had a high risk for low birth weight (OR = 1.42, 95% CI: 1.15-2.08) and small for gestational age (OR = 1.62, 95% CI: 1.23-2.11). Dose-response analyses indicated that 21.0 kg/m2 may be the appropriate tipping point pBMI for risk for maternal or infant complications in Chinese women. CONCLUSION: A high or low pBMI is associated with the risk for maternal or infant complications and partly mediated by GDM. A lower pBMI cutoff of 21 kg/m2 may be appropriate for risk for maternal or infant complications in pregnant Chinese women.

In situ activation of COOH-functionalized ZIF-90-enabled reductive CO2N-formylation.

A heterogeneous ZIF-90-based catalyst functionalized with COOH and with a porous structure was facilely prepared for efficient CO2 adsorption and activation to undergo reductive N-formylation with a wide range of amines (15 examples) to furnish N-formamides (78-94% yields). The -COO- species generated by an in situ interaction with amine acts as a key species for activating hydrosilane to capture CO2, and remarkably facilitates a cascade C-N coupling and hydrogenation process. Our findings show a facile strategy for the rational construction of robust active sites for reductive CO2 valorization.

Oxidative C-C bond cleavage of lignin via electrocatalysis.

Lignin, which is an important component of biomass in nature and is constantly produced in industry, becomes potential raw material for sustainable production of fine chemicals and biofuels. Electrocatalysis has been extensively involved in the activation of simple molecules and cleavage-recasting of complex scaffolds in an elegant environment. As such, electrocatalytic cleavage of C-C(O) in ß-O-4 model molecules of lignin to value-added chemicals has received much attention in recent years. This mini-review introduces various anodes (e.g., Pb, Pt, Ni, Co., and Ir) developed for electro-oxidative lignin degradation (EOLD) under mild conditions. Attention was placed to understand the conversion pathways and involved reaction mechanisms during EOLD, with emphasis on the product distribution caused by different electrodes.

Development of Sustainable Catalytic Pathways for Furan Derivatives.

Biomass, the only globally available, renewable feedstock of organic carbon, is considered a viable alternative to fossil fuels. It can be efficiently utilized to produce various building blocks in accordance with green and sustainable chemistry principles. In this review, recent progress, such as the transformation of carbohydrates (C5 or C6 sugar, inulin, and cellulose) and their derivatives (furfural, hydroxymethylfurfural) into significant platform chemicals over polyoxometalates, zeolites, non-noble metals, and ionic liquids in single or multiphase, is evaluated.

Comparison of detection strategies for screening and confirming congenital cytomegalovirus infection in newborns in a highly seroprevalent population: a mother-child cohort study.

BACKGROUND: Universal screening of congenital cytomegalovirus (cCMV) infection is important for monitoring and intervention during critical stages of speech and language development. This study aimed to explore the optimal detection strategy for cCMV infection screening. METHODS: Serum samples from pregnant women and saliva and urine samples from their newborns were collected for the anti-CMV IgG and CMV DNA PCR tests, respectively. The sensitivity, specificity, and predictive values as well as the likelihood ratios of 12 potential screening strategies for cCMV infection, based on tests for saliva, urine, and their combination, were evaluated. FINDINGS: A total of 6729 pregnant women were enrolled, and the seroprevalence was 98.1%. Among 6350 newborns that were followed up, 49 were defined as having cCMV infection. In the screening test, the CMV DNA positivity rate remained similar from day 0 to day 5, increased slowly from day 6 to day 13, and became high in newborns beyond 13 days of birth. In the confirmatory testing, the positive rates increased significantly beyond day 21. For the 49 newborns with cCMV infection, the proportion of agreement between saliva and urine testing was poor. Upon evaluating alternative screening strategies, using saliva and urine screening with saliva and urine confirmation as the reference strategy, saliva screening with saliva and urine confirmation showed good diagnostic accuracy and feasibility, with sensitivity, specificity, positive predictive and negative predictive values of 85.7%, 100.0%, 100.0% and 99.9%, respectively. INTERPRETATION: In populations with high seroprevalence, saliva screening with saliva and urine confirmation might be an alternative strategy for screening cCMV infections. The suggested timeframes for screening and confirmation are within 13 (ideally 5) and 21 (ideally 13) days of birth, respectively. FUNDING: National Natural Science Foundation of China, National Science and Technology Major Project of China and Merck & Co., Inc., Kenilworth, New Jersey, U.S.A.

Advances in Pretreatment of Straw Biomass for Sugar Production.

Straw biomass is an inexpensive, sustainable, and abundant renewable feedstock for the production of valuable chemicals and biofuels, which can surmount the main drawbacks such as greenhouse gas emission and environmental pollution, aroused from the consumption of fossil fuels. It is rich in organic content but is not sufficient for extensive applications because of its natural recalcitrance. Therefore, suitable pretreatment is a prerequisite for the efficient production of fermentable sugars by enzymatic hydrolysis. Here, we provide an overview of various pretreatment methods to effectively separate the major components such as hemicellulose, cellulose, and lignin and enhance the accessibility and susceptibility of every single component. This review outlines the diverse approaches (e.g., chemical, physical, biological, and combined treatments) for the excellent conversion of straw biomass to fermentable sugars, summarizes the benefits and drawbacks of each pretreatment method, and proposes some investigation prospects for the future pretreatments.

Cohort profile: the Chinese Pregnant Women Cohort Study and Offspring Follow-up (CPWCSaOF).

PURPOSE: A multicentre prospective cohort study, known as the Chinese Pregnant Women Cohort Study (CPWCS), was established in 2017 to collect exposure data during pregnancy (except environmental exposure) and analyse the relationship between lifestyle during pregnancy and obstetric outcomes. Data about mothers and their children's life and health as well as children's laboratory testing will be collected during the offspring follow-up of CPWCS, which will enable us to further investigate the longitudinal relationship between exposure in different periods (during pregnancy and childhood) and children's development. PARTICIPANTS: 9193 pregnant women in 24 hospitals in China who were in their first trimester (5-13 weeks gestational age) from 25 July 2017 to 26 November 2018 were included in CPWCS by convenience sampling. Five hospitals in China which participated in CPWCS with good cooperation will be selected as the sample source for the Chinese Pregnant Women Cohort Study (Offspring Follow-up) (CPWCS-OF). FINDINGS TO DATE: Some factors affecting pregnancy outcomes and health problems during pregnancy have been discovered through data analysis. The details are discussed in the 'Findings to date' section. FUTURE PLANS: Infants and children and their mothers who meet the criteria will be enrolled in the study and will be followed up every 2 years. The longitudinal relationship between exposure (questionnaire data, physical examination and biospecimens, medical records, and objective environmental data collected through geographical information system and remote sensing technology) in different periods (during pregnancy and childhood) and children's health (such as sleeping problem, oral health, bowel health and allergy-related health problems) will be analysed. TRAIL REGISTRATION NUMBER: CPWCS was registered with ClinicalTrials.gov on 18 January 2018: NCT03403543. CPWCS-OF was registered with ClinicalTrials.gov on 24 June 2020: NCT04444791.

Current Approaches to Alkyl Levulinates via Efficient Valorization of Biomass Derivatives.

Biomass is a potential non-food, carbon-neutral, and abundant resource, which can be used as an alternative to fossil fuels during the sustainable preparation of various platform chemicals. Alkyl levulinates (ALs) have found widespread application as flavorings, plasticizing agents, and fuel additives, as well as synthetic precursors to various building blocks. Several processes have been investigated to transform biomass and its derivatives into ALs, which mainly include: (i) direct esterification of levulinic acid (LA) with alkyl alcohols and (ii) alcoholysis reactions of renewable biomass feedstocks and their derivatives, including furfuryl alcohol (FAL), chloromethyl furfural (CMF), and saccharides. This review focuses on illustrating the effects of the biomass pretreatment step, catalyst texture, possible mechanisms, acidities, and intermediates on the synthesis of ALs from sustainable resources covering a wide range of intermediates, including diethyl ether (DEE), 4,5,5-triethoxypentan-2-one (TEP), ethoxymethylfuran (EMF), ethyl-D-fructofuranoside (EDFF), and ethyl-D-glucopyranoside (EDGP).

Heteropoly Acid-Based Catalysts for Hydrolytic Depolymerization of Cellulosic Biomass.

Cellulose is the most abundant source of biomass, which can be converted into monosaccharide or other chemical platform molecules for the sustainable production of chemicals and fuels. Acid catalysts can promote hydrolytic degradation of cellulose into valuable platform molecules, which is of great significance in the development of chemicals and biofuels. However, there are still some shortcomings and limitations of the catalysts for the hydrolytic degradation of cellulosic biomass. Heteropoly acid (HPA), as a green catalyst, seems to be more conducive to the degradation of cellulosic biomass due to its extreme acidity. HPAs can be designed in homogeneous and heterogeneous systems. Moreover, they can be easily separated from the products in both systems by a simple extraction process. According to the unique properties of HPAs (e.g., good solubility, high thermal stability, and strong acidity), using heteropoly acid-based catalysts to depolymerize and convert cellulose into value-added chemicals and biofuels has become one of the most remarkable processes in chemistry for sustainability. In this review, the characteristics, advantages, and applications of HPAs in different categories for cellulose degradation, especially hydrolysis hydrolytic degradation, are summarized. Moreover, the mechanisms of HPAs catalysts in the effective degradation of cellulosic biomass are discussed. This review provides more avenues for the development of renewed and robust HPAs for cellulose degradation in the future.

CO2 -Enabled Biomass Fractionation/Depolymerization: A Highly Versatile Pre-Step for Downstream Processing.

Lignocellulosic biomass is inevitably subject to fractionation and depolymerization processes for enhanced selectivity toward specific products, in most cases prior to catalytic upgrading of the three main fractions-cellulose, hemicellulose, and lignin. Among the developed pretreatment techniques, CO2 -assisted biomass processing exhibits some unique advantages such as the lowest critical temperature (31.0 °C) with moderate critical pressure, low cost, nontoxicity, nonflammability, ready availability, and the addition of acidity, alongside easy recovery by pressure release. This Review showcases progress in the study of sub- or supercritical CO2 -mediated thermal processing of lignocellulosic biomass-the key pre-step for downstream conversion processes. The auxo-action of CO2 in biomass pretreatment and fractionation, along with the involved variables, direct degradation of untreated biomass in CO2 by gasification, pyrolysis, and liquefaction with relevant conversion mechanisms, and CO2 -enabled depolymerization of lignocellulosic fractions with representative reaction pathways are summarized. Moreover, future prospects for the practical application of CO2 -assisted up- and downstream biomass-to-bioproduct conversion are also briefly discussed.

Recent advances in liquid hydrosilane-mediated catalytic N-formylation of amines with CO2.

Carbon dioxide is an ideal raw material for the synthesis of complex organic compounds because of its rich, non-toxic, and good physical properties. It is of great significance to transform CO2 into valuable fine chemicals and develop a green sustainable cycle of carbon surplus. Based on hydrosilane as a reducing agent, this work summarizes the recent applications of reductive amidation of CO2 using different catalysts such as organocatalysts, ionic liquids (ILs), salts, transition metal complexes, and solvents. The main factors affecting the reductive amidation of CO2 and the possible reaction mechanism are discussed. Moreover, the future orientation and catalytic systems of the formylation of amines with CO2 and hydrosilane are prospected.

A Facile Direct Route to N-(Un)substituted Lactams by Cycloamination of Oxocarboxylic Acids without External Hydrogen.

Lactams are privileged in bioactive natural products and pharmaceutical agents and widely featured in functional materials. This study presents a novel versatile approach to the direct synthesis of lactams from oxocarboxylic acids without catalyst or external hydrogen. The method involves the in situ release of formic acid from formamides induced by water to facilitate efficient cycloamination. Water also suppresses the formation of byproducts. This unconventional pathway is elucidated by a combination of model experiments and density functional theory calculations, whereby cyclic imines (5-methyl-3,4-dihydro-2-pyrrolone and its tautomeric structures) are found to be favorable intermediates toward lactam formation, in contrast to the conventional approach encompassing cascade reductive amination and cyclization. This sustainable and simple protocol is broadly applicable for the efficient production of various N-unsubstituted and N-substituted lactams.

[Studies on flavonoids from Derris eriocarpa].

Derris eriocarpa, a traditional Chinese medicine belonging to the family of Leguminosae, is widely distributed mainly over Yunnan, Guangxi and Guizhou of China. Modern pharmacological researches on this herb showed that it had extensive bioactivities, such as promoting urination, removing dampness and cough and reducing inspissated mucus and other biological activities. The extensive studies on the chemical constituents of this plant have resulted in the isolation of triterpenoids, steroids, fatty acid and others, but the flavone compounds haven't reported before. In our further research on the ethyl acetate of this plant, nine flavone compounds were obtained by column chromatography on silica gel, Sephadex LH-20, semi-prep HPLC, polyamide column chromatography and recrystallization for separation and purification. The structures were determined on the basis of extensive spectroscopic analysis, including MS, NMR experiments and comparison with spectroscopic data in the literature, respectively, as diosmetin (1), 3, 3'-di-O-methylquercetin (2), afromosin (3), 6, 3'-dihydroxy-7, 4'-dimethoxyisoflavone (4), odoratin (5), 7, 3'-dihydroxy-8, 4'-dimethoxyisoflavone (6), 6, 4'-dihydroxy-7, 3'-dimethoxyisoflavone (7), 5, 7, 4'-trihydroxy-3, 3', 5'-trimethoxyflavone (8), and alpinumisoflavone (9). All these compounds were isolated from Derris eriocarpa How for the first time. And the in vitro assays showed that compound 2 possessed moderate inhibitory activity against human cancer cells K562 and HEL.