Transition metal-catalyzed organic electrochemistry is a rapidly growing research area owing in part to the ability of metal catalysts to alter the selectivity of a given transformation. This ...conversion mainly focuses on transition metal-catalyzed anodic oxidation and cathodic reduction and great progress has been achieved in both areas. Typically, only one of the half-cell reactions is involved in the organic reaction while a sacrificial reaction occurs at the counter electrode, which is inherently wasteful since one electrode is not being used productively. Recently, transition metal-catalyzed paired electrolysis that makes use of both anodic oxidation and cathodic reduction has attracted much attention. This perspective highlights the recent progress of each type of electrochemical reaction and relatively focuses on the transition metal-catalyzed paired electrolysis, showcasing that electrochemical reactions involving transition metal catalysis have advantages over conventional reactions in terms of controlling the reaction activity and selectivity and figuring out that transition metal-catalyzed paired electrolysis is an important direction of organic electrochemistry in the future and offers numerous opportunities for new and improved organic reaction methods.
Transition metal-catalyzed organic electrochemistry is a rapidly growing research area owing in part to the ability of metal catalysts to alter the selectivity of a given transformation.
A scalable enantioselective nickel-catalyzed electrochemical reductive homocoupling of aryl bromides has been developed, affording enantioenriched axially chiral biaryls in good yield under mild ...conditions using electricity as a reductant in an undivided cell. Common metal reductants such as Mn or Zn powder resulted in significantly lower yields in the absence of electric current under otherwise identical conditions, underscoring the enhanced reactivity provided by the combination of transition metal catalysis and electrochemistry.
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•Superb and reusable adsorbent WSH was successfully synthesized from shrimp shells.•Maximum adsorption capacity of WSH was 755.08 mg/g at optimal pH of 4.0.•Exothermic adsorption was ...spontaneous and followed monolayer adsorption pattern.•Electrostatic interaction was mainly responsible for the prominent adsorption.
Shrimp processing and consumption generate large amounts of waste shrimp shell (WSS) rich in chitin and protein. Herein, we successfully synthesized WSS-based hydrochar (WSH) adsorbent through deproteinization and deacetylation followed by hydrothermal carbonization (HTC) and acid washing. For comparison, another hydrochar (CCH) adsorbent was synthesized from HTC of commercial chitosan under identical conditions. Specifically, WSH contained rich nitrogen-containing functional groups with a long aliphatic chains structure. Acid etching of calcium carbonate in WSS led to a higher specific surface area of WSH (12.65 m2/g) which was nearly 6 times higher than that of CCH (2.13 m2/g). The lower deacetylation degree of WSH was responsible for higher amide I and amino groups retained therein. Under an optimal initial solution pH of 4.0, WSH could rapidly achieve a superb adsorption capacity of 755.08 mg/g for methyl orange molecule. Moreover, the adsorption process followed a pseudo-second-order kinetics model and was well described by a monolayer adsorption pattern based on the Langmuir isotherm model with correlation coefficients higher than 0.9989. Prominent adsorption performance of WSH for methyl orange was mainly attributed to electrostatic interactions, while steric hindrance effect had a detrimental impact on the adsorption capacity of CCH. Superb adsorption capacity and excellent regeneration performance suggest WSH could be a promising and affordable adsorbent candidate for anionic dye removal.
•Aqueous phase recycling of sewage sludge hydrothermal carbonization was investigated.•The O/C and H/C atomic ratios revealed that dehydration was the main reaction during hydrothermal ...carbonization.•The pH value step increased with increasing recycling number, indicating that aqueous phase acted as a catalyst.•The organic matter recovery from the aqueous phase influenced on the combustion property of hydrochar.
In this study, the aqueous phase produced from the hydrothermal carbonization (HTC) of sewage sludge (SS) with pure water was reused for the HTC of fresh SS, aiming to maximize energy recovery from the aqueous phase. The aqueous phase was recycled four times. The effects of aqueous phase recycling on the properties of the aqueous phase and hydrochar produced at temperatures of 200, 230, and 260 °C were studied. The hydrochar yield always decreased with increasing temperature regardless of whether the aqueous phase was recycled. The C and N contents and higher heating values of the hydrochars produced with aqueous phase recycling were all higher than that of the hydrochar produced with pure water and slightly increased as the number of recycling times increased. The O/C and H/C atomic ratios of the hydrochars revealed that dehydration was the main reaction pathway during HTC of SS. The pH value of the aqueous phase increased as the number of recycling times increased, indicating that the concentration of NH4+-N in the aqueous phase increased. The process of aqueous phase recycling affected the carbonization of the hydrochar. These results suggest that aqueous phase recycling was favorable for energy recovery from the aqueous phase produced from the HTC of SS and for improving the combustion properties of the hydrochar. Thus, we believe that aqueous phase recycling was a promising strategy for energy recovery, aqueous phase disposal, and the production of high-quality hydrochar with respect to the HTC of SS.
An electrochemical asymmetric coupling of secondary acyclic amines with ketones via a Shono-type oxidation has been described, affording the corresponding amino acid derivatives with good to ...excellent diastereoselectivity and enantioselectivity. The addition of an N-oxyl radical as a redox mediator could selectively oxidize the substrate rather than the product, although their oxidation potential difference is subtle (about 13 mV). This electrochemical transformation proceeds in the absence of stoichiometric additives, including metals, oxidants, and electrolytes, which gives it good functional group compatibility. Mechanistic studies suggest that proton-mediated racemization of the product is prevented by the reduction of protons at the cathode.
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•The LDHs and LDO were prepared and characterized to catalyze removal nitrogen element in hydrochar.•Mg-Al LDO showed the highest efficiency for the removal of nitrogen among the ...catalysts.•Partial floc directly transformed to hydrochar according to “solid-solid” reaction.•The possibility reaction pathways of removal nitrogen during HTC were proposed.
The high content of nitrogen in hydrochar produced from hydrothermal carbonization (HTC) of sewage sludge (SS) leads to serious NOx pollution when the hydrochar is used as a solid fuel. Mg-Ga layered double hydroxides (LDHs), Mg-Al LDHs and their calcined samples (layered double oxides, LDO) were prepared. The LDHs and LDO all can notably promote the removal of nitrogen element, in which organic-N was transferred to NH4+-N to cause increasing pH value. Mg-Al LDO showed the highest efficiency for the removal of nitrogen among the catalysts. The thermal decomposition of the N-organic matter with acidic sites in catalyst was the key step to release NH3. The key role of basic sites in Mg-Al LDO was that it can effectively destroy the cell wall and extracellular polymeric substances structure. The lipid-like substance did not participate in the carbonization reaction, but they can be absorbed by the hydrochar. Partial SS floc directly transformed to hydrochar according to “solid-solid” reaction. The reaction pathways of remove nitrogen were proposed.
Background
Environmental pollutants, which coexist with allergens, have been associated with the exacerbation of asthma. However, the underlying molecular mechanisms remain elusive. We sought to ...determine whether benzo(a)pyrene (BaP) co‐exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1‐induced asthma and its underlying mechanisms.
Methods
The effect of BaP was investigated in Der f 1‐induced mouse model of asthma, including airway hyper‐responsiveness, allergic inflammation, and epithelial‐derived cytokines. The impact of BaP on Der f 1‐induced airway epithelial cell oxidative stress (ROS) and cytokine release was further analyzed. The role of aryl hydrocarbon receptor (AhR) signaling in BaP‐promoted Der f 1‐induced ROS, cytokine production, and allergic inflammation was also investigated.
Results
Compared with Der f 1, BaP co‐exposure with Der f 1 led to airway hyper‐responsiveness and increased lung inflammation in mouse model of asthma. Increased expression of TSLP, IL‐33, and IL‐25 was also found in the airways of these mice. Moreover, BaP co‐exposure with Der f 1 activated AhR signaling with increased expression of AhR and CYP1A1 and promoted airway epithelial ROS generation and TSLP and IL‐33, but not IL‐25, expression. Interestingly, AhR antagonist CH223191 or cells with AhR knockdown abrogated the increased expression of ROS, TSLP, and IL‐33. Furthermore, ROS inhibitor N‐acetyl‐L‐cysteine (NAC) also suppressed BaP co‐exposure‐induced expression of epithelial TSLP, IL‐33, and IL‐25. Finally, AhR antagonist CH223191 and NAC inhibited BaP co‐exposure with Der f 1‐induced lung inflammation.
Conclusions
Our findings suggest that BaP facilitates Der f 1‐induced epithelial cytokine release through the AhR‐ROS axis.
Compared with Der f 1 alone, BaP and Der f 1 co‐exposure leads to airway hyperresponsiveness and increases Th2‐associated lung inflammation in mouse model of asthma. AhR signaling plays a critical role in BaP and Der f 1 co‐exposure‐induced oxidative stress and cytokine expression in airway epithelial cells. The AhR‐ROS axis regulates BaP and Der f 1 co‐exposure‐induced epithelial cytokine expression and allergic inflammation. AhR: Aryl hydrocarbon receptor; BaP: benzo(a)pyrene; CLRs: C‐type lectin receptors; HDM: house dust mite; PAR2: protease‐activated receptor 2; ROS: reactive oxygen species.
Previous studies have shown increasing prevalence of diabetes in China, which now has the world's largest diabetes epidemic.
To estimate the recent prevalence and to investigate the ethnic variation ...of diabetes and prediabetes in the Chinese adult population.
A nationally representative cross-sectional survey in 2013 in mainland China, which consisted of 170 287 participants.
Fasting plasma glucose and hemoglobin A1c levels were measured for all participants. A 2-hour oral glucose tolerance test was conducted for all participants without diagnosed diabetes.
Primary outcomes were total diabetes and prediabetes defined according to the 2010 American Diabetes Association criteria. Awareness and treatment were also evaluated. Hemoglobin A1c concentration of less than 7.0% among treated diabetes patients was considered adequate glycemic control. Minority ethnic groups in China with at least 1000 participants (Tibetan, Zhuang, Manchu, Uyghur, and Muslim) were compared with Han participants.
Among the Chinese adult population, the estimated standardized prevalence of total diagnosed and undiagnosed diabetes was 10.9% (95% CI, 10.4%-11.5%); that of diagnosed diabetes, 4.0% (95% CI, 3.6%-4.3%); and that of prediabetes, 35.7% (95% CI, 34.1%-37.4%). Among persons with diabetes, 36.5% (95% CI, 34.3%-38.6%) were aware of their diagnosis and 32.2% (95% CI, 30.1%-34.2%) were treated; 49.2% (95% CI, 46.9%-51.5%) of patients treated had adequate glycemic control. Tibetan and Muslim Chinese had significantly lower crude prevalence of diabetes than Han participants (14.7% 95% CI, 14.6%-14.9% for Han, 4.3% 95% CI, 3.5%-5.0% for Tibetan, and 10.6% 95% CI, 9.3%-11.9% for Muslim; P < .001 for Tibetan and Muslim compared with Han). In the multivariable logistic models, the adjusted odds ratios compared with Han participants were 0.42 (95% CI, 0.35-0.50) for diabetes and 0.77 (95% CI, 0.71-0.84) for prediabetes for Tibetan Chinese and 0.73 (95% CI, 0.63-0.85) for diabetes and 0.78 (95% CI, 0.71-0.86) for prediabetes in Muslim Chinese.
Among adults in China, the estimated overall prevalence of diabetes was 10.9%, and that for prediabetes was 35.7%. Differences from previous estimates for 2010 may be due to an alternate method of measuring hemoglobin A1c.
A novel strategy for asymmetric Shono-type oxidative cross-coupling has been developed by merging copper catalysis and electrochemistry, affording C1-alkynylated tetrahydroisoquinolines with good to ...excellent enantioselectivity. The use of TEMPO as a co-catalytic redox mediator is crucial not only for oxidizing a tetrahydroisoquinoline to an iminium ion species but also for decreasing the oxidation potential of the reaction. A novel bisoxazoline ligand is also reported.
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The treatment of wastewater not only helps to alleviate the scarcity of water and environmental challenges but also generates a by-product called Municipal Sewage Sludge (MSS). The ...MSS is a high moisture precipitant with plentiful organic and inorganic components. However, some pollutants in MSS components and its high-water content complicate its valorization, and thus, special attention is required for its valorization. Hydrothermal treatments (HTs) can be applied to feedstocks with high moisture content without pre-drying. These processes are gaining more attention to processing MSS into fuels and value-added materials. This work systematically reviews the findings recently emerged from HTs of MSS. The related chemical reactions and the effect of reaction parameters are highlighted based on most recent works. The problems addressed and those not yet addressed are also discussed. Some suggestions are made for the plausible applications of end products with the aim to optimize the whole process. Finally, insight is given into the future of MSS HTs and the concerns that might be the focus of substantial studies.
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