Herein, we report an unprecedented implementation of 3-halooxindoles as C–C–O three-atom components for (3+3) cycloaddition with pyridinium 1,4-zwitterionic thiolates, affording structurally diverse ...indolenine-fused 2H-1,4-oxathiines in moderate to high yields. A combined experimental and computational mechanistic study suggests that the reaction proceeds through addition of a S conjugate to the o-azaxylylene intermediate, followed by O-Michael addition and a sequential retro-Michael addition/pyridine extrusion pathway.
A severe dust storm event originated from the Gobi Desert in Central and East
Asia during 2–7 May 2017. Based on Moderate Resolution Imaging
Spectroradiometer (MODIS) satellite products, hourly ...environmental monitoring
measurements from Chinese cities and East Asian meteorological observation
stations, and numerical simulations, we analysed the spatial and temporal
characteristics of this dust event as well as its associated impact on the
Asia-Pacific region. The maximum observed hourly PM10 (particulate
matter with an aerodynamic diameter ≤ 10 µm) concentration
was above 1000 µg m−3 in Beijing, Tianjin, Shijiazhuang,
Baoding, and Langfang and above 2000 µg m−3 in Erdos, Hohhot,
Baotou, and Alxa in northern China. This dust event affected over
8.35 million km2, or 87 % of the Chinese mainland, and significantly deteriorated air quality in 316 cities of
the 367 cities examined across China. The maximum surface wind speed during
the dust storm was 23–24 m s−1 in the Mongolian Gobi Desert and
20–22 m s−1 in central Inner Mongolia, indicating the potential
source regions of this dust event. Lidar-derived vertical dust profiles in
Beijing, Seoul, and Tokyo indicated dust aerosols were uplifted to an
altitude of 1.5–3.5 km, whereas simulations by the Weather Research and
Forecasting with Chemistry (WRF-Chem) model indicated 20.4 and 5.3 Tg of
aeolian dust being deposited respectively across continental Asia and the
North Pacific Ocean. According to forward trajectory analysis by the FLEXible
PARTicle dispersion (FLEXPART) model, the East Asian dust plume moved across
the North Pacific within a week. Dust concentrations decreased from the East
Asian continent across the Pacific Ocean from a magnitude of 103 to
10−5 µg m−3, while dust deposition intensity ranged from
104 to 10−1 mg m−2. This dust event was unusual due to its
impact on continental China, the Korean Peninsula, Japan, and the North
Pacific Ocean. Asian dust storms such as those observed in early May 2017 may
lead to wider climate forcing on a global scale.
Background
The gut is implicated in the pathogenesis of acute pancreatitis (AP) and the infectious complications of AP are commonly associated with enteric bacteria, yet whether gut microbiota ...dysbiosis participants in AP severity remains largely unknown.
Methods
We collected clinical information and fecal samples from 165 adult participants, including 41 with mild AP (MAP), 59 with moderately severe AP (MSAP), 30 with severe AP (SAP) and 35 healthy controls (HC). The serum inflammatory cytokines and gut barrier indexes were detected. Male C57BL/6 mice with AP were established and injuries of pancreas were evaluated in antibiotic-treated mice, germ-free mice as well as those transplanted with fecal microbiota. The gut microbiota was analyzed by 16S rRNA gene sequencing.
Results
The structure of gut microbiota was significantly different between AP and HC, and the disturbed microbiota was closely correlated with systematic inflammation and gut barrier dysfunction. Notably, the microbial composition changed further with the worsening of AP and the abundance of beneficial bacteria such as
Blautia
was decreased in SAP compared with MAP and MSAP. The increased capacity for the inferred pathway, bacterial invasion of epithelial cells in AP, highly correlated with the abundance of
Escherichia
–
Shigella
. Furthermore, the antibiotic-treated mice and germ-free mice exhibited alleviated pancreatic injury after AP induction and subsequent fecal microbiota transplantation in turn exacerbated the disease.
Conclusions
This study identifies the gut microbiota as an important mediator during AP and its dysbiosis is associated with AP severity, which suggests its role as potential therapeutic target.
•A building cooling load prediction model was optimized by wavelet decomposition.•The model’s prediction accuracy was verified at two short-term time scales.•A correlation analysis was conducted to ...apply factors under different frequency bands.
Building cooling load predictions can be used to better understand energy demands and to improve the energy efficiency of HVAC systems. In this study, GA-SVR and GA-WD-SVR prediction models for short-term and ultra-short-term predictions for office buildings are established. The short-term cooling load prediction model is designed to outline an HVAC system’s operation strategies for the following day. The ultra-short-term cooling load prediction model is designed to inform building managers of the cooling load for the next hour and to adjust HVAC system operations in advance. An office building in Tianjin is used to train and evaluate the load prediction models. Meteorological data and one-day-ahead and one-hour-ahead cooling load records are used as model inputs. The prediction results indicate that the GA-SVR prediction model performs better for short-term cooling load prediction with MRE and R2 of 6.5% and 73.1%, respectively, while the GA-WD-SVR prediction model performs better for ultra-short-term cooling load prediction with MRE and R2 of 4.6% and 88.7%, respectively.
In this study, a super-fine steel slag with the specific surface area of 786m2/kg was prepared by mechanical grinding. Its cementitious properties were investigated by comparing the results obtained ...from it with those obtained from ordinary steel slag, fly ash, and cement. The results show that the super-fine steel slag exhibits a much higher activity at early and middle ages but a lower activity at late ages than the ordinary steel slag. Though the specific surface area of the super-fine steel slag is much larger than that of cement, the activity of the super-fine steel slag is still obviously lower than that of cement. The super-fine steel slag replacement tends to weaken the cementitious properties of the composite binder. As compared to fly ash, the super-fine steel slag tends to make more contributions to the hardening of concrete at early ages but far less contributions at late ages. Overall, it seems that it is uneconomical to produce super-fine steel slag by mechanical grinding.
A super-fine steel slag with the specific surface area of 786m2/kg was prepared. Though the activity of the fine steel slag is higher than that of the coarse steel slag, it is still lower than that of fly ash and even lower than that of cement. Display omitted
•Increasing fineness improves the early activity of steel slag.•The activity of the super-fine steel slag is much lower than that of cement.•The super-fine steel slag makes far less contributions than fly ash at late ages.
Building biomimetic polymer vesicles that can sense a biological signaling molecule is a tremendous challenge at the cross-frontier of chemistry and biology. We develop a new class of ...o-azidomethylbenzoate (AzMB)-containing block copolymer that can respond to an endogenous signaling molecule, hydrogen sulfide (H2S). Such a gasotransmitter can trigger cascade chemical reactions to sever the AzMB side functionalities, which alters the polymer amphiphilicity and further leads to a controllable disassembly of their self-assembly vesicular nanostructure. Moreover, if we introduce cystathionine γ-lyase (CSE), a specific enzyme converting cysteine into H2S, onto the vesicle membrane, the polymersomes can extend their responsive scope from H2S to a specific amino acid bioactivator. We anticipate that this polymer model could open up a new avenue for constructing biosignal-triggered nanocapsules for intracellular applications.
Cholesterol is an indispensable component of the cell membrane and plays vital roles in critical physiological processes. Brain cholesterol accounts for a large portion of total cholesterol in the ...human body, and its content must be tightly regulated to ensure normal brain function. Disorders of cholesterol metabolism in the brain are linked to neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and other atypical cognitive deficits that arise at old age. However, the specific role of cholesterol metabolism disorder in the pathogenesis of neurodegenerative diseases has not been fully elucidated. Statins that are a class of lipid-lowering drugs have been reported to have a positive effect on neurodegenerative diseases. Herein, we reviewed the physiological and pathological conditions of cholesterol metabolism and discussed the possible mechanisms of cholesterol metabolism and statin therapy in neurodegenerative diseases.
Abstract
Eicosapentaenoic acid (EPA), an omega-3 fatty acid, has been widely used to prevent cardiovascular disease (CVD) and treat brain diseases alone or in combination with docosahexaenoic acid ...(DHA). However, the impact of EPA and DHA supplementation on normal cognitive function and the molecular targets of EPA and DHA are still unknown. We show that acute administration of EPA impairs learning and memory and hippocampal LTP in adult and prepubescent mice. Similar deficits are duplicated by endogenously elevating EPA in the hippocampus in the transgenic fat-1 mouse. Furthermore, the damaging effects of EPA are mediated through enhancing GABAergic transmission via the 5-HT
6
R. Interestingly, DHA can prevent EPA-induced impairments at a ratio of EPA to DHA similar to that in marine fish oil via the 5-HT
2C
R. We conclude that EPA exhibits an unexpected detrimental impact on cognitive functions, suggesting that caution must be exercised in omega-3 fatty acid supplementation and the combination of EPA and DHA at a natural ratio is critical for learning and memory and synaptic plasticity.
Two polysaccharides CAVAP-I and CAVAP-II from Citrus aurantium L. var. amara Engl showed significant structural differences. Average molecular weights of CAVAP-I and CAVAP-II were 10.5kDa and 4.5kDa. ...Triple-helix conformation existed in CAVAP-II rather than CAVAP-I. Arabinose, mannose, glucose and galactose formed main components of CAVAP-I and CAVAP-II at different ratios. (1→3,6)-β-d-Gal and (1→5)-α-l-Ara composed the backbone of CAVAP-I and CAVAP-II. CAVAP-II displayed greater immune enhancement potential than CAVAP-I. CAVAP-II significantly promoted interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) production, and inducible nitric oxide synthase, IL-6, TNF-α and interleukin-1 beta mRNA expression by activating phosphorylated extracellular signal-regulated kinase, c-Jun N-terminal kinase, P38 and P65. These results indicated that structures were closely related to immunomodulatory activity of polysaccharides. CAVAP-II showed the greatest immunostimulation potential followed by CAVAP-I and CAVAPs by activating mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) pathways.
A palladium-catalyzed enantioselective decarboxylative allylic alkylation of α-benzyl cyanoacetates with methylene cyclic carbamates has been successfully developed. An array of enantioenriched ...products bearing nitrile-containing acyclic quaternary carbon stereocenters were obtained in high yields with good enantioselectivities (up to 99% yield and 93% ee). This method provides a new tactic for the construction of chiral nitrile-containing acyclic quaternary carbon stereocenters.
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