Search

An iron‐catalyzed trifluoromethylation of indole‐tethered alkene with Togni's reagent to construct CF3‐containing spiro[indole‐3,3′‐pyrrolidine] and tetrahydrocarbazole derivatives under mild and convenient conditions has been disclosed. Mechanistic studies indicate that the reaction proceed through a CF3 radical addition to the alkene, followed by sequential dearomatizing spiocyclization of the indole and oxidation to afford the spiro[indole‐3,3′‐pyrrolidine] derivatives. Meanwhile, when the substituent at the C2 position of the indole is hydrogen, the CF3‐containing tetrahydrocarbazole is obtained through trifluoromethylation of alkene and cyclization of indole. [ABSTRACT FROM AUTHOR]

Constructing nitrogen (N2) adsorption and activation sites on semiconductors is the key to achieving efficient N2 photofixation. Herein, Mn–W dual‐metal sites on WO3 are designed toward efficient N2 photoreduction via controlled Mn doping. Impressively, the optimal 2.3% Mn‐doped WO3 (Mn‐WO3) exhibits a remarkable ammonia (NH3) production rate of 425 µmol gcat.−1 h−1, representing the best catalytic performance among the ever‐reported tungsten oxide‐based photocatalysts for N2 fixation. Quasi in situ synchrotron radiation X‐ray spectroscopy directly identifies that the Mn–W dual‐metal sites can enhance the polarization of the adsorbed N2, which is beneficial to the N2 activation. Further theoretical calculations reveal that the increased polarization is originated from the electron back‐donation into the antibonding orbitals of the adsorbed N2, hence lowering the reaction energy barrier toward the N2 photofixation. The concept of dual sites construction for inert molecule activation offers a powerful platform toward rational design of highly efficient catalysts for nitrogen fixation and beyond. [ABSTRACT FROM AUTHOR]

Constructing nitrogen (N2) adsorption and activation sites on semiconductors is the key to achieving efficient N2 photofixation. Herein, Mn–W dual‐metal sites on WO3 are designed toward efficient N2 photoreduction via controlled Mn doping. Impressively, the optimal 2.3% Mn‐doped WO3 (Mn‐WO3) exhibits a remarkable ammonia (NH3) production rate of 425 µmol gcat.−1 h−1, representing the best catalytic performance among the ever‐reported tungsten oxide‐based photocatalysts for N2 fixation. Quasi in situ synchrotron radiation X‐ray spectroscopy directly identifies that the Mn–W dual‐metal sites can enhance the polarization of the adsorbed N2, which is beneficial to the N2 activation. Further theoretical calculations reveal that the increased polarization is originated from the electron back‐donation into the antibonding orbitals of the adsorbed N2, hence lowering the reaction energy barrier toward the N2 photofixation. The concept of dual sites construction for inert molecule activation offers a powerful platform toward rational design of highly efficient catalysts for nitrogen fixation and beyond. [ABSTRACT FROM AUTHOR]

Summary: To address the vast multimedia traffic volume and requirements of user quality of experience in the next‐generation mobile communication system (5G), it is imperative to develop efficient content caching strategy at mobile network edges, which is deemed as a key technique for 5G. Recent advances in edge/cloud computing and machine learning facilitate efficient content caching for 5G, where mobile edge computing can be exploited to reduce service latency by equipping computation and storage capacity at the edge network. In this paper, we propose a proactive caching mechanism named learning‐based cooperative caching (LECC) strategy based on mobile edge computing architecture to reduce transmission cost while improving user quality of experience for future mobile networks. In LECC, we exploit a transfer learning‐based approach for estimating content popularity and then formulate the proactive caching optimization model. As the optimization problem is NP‐hard, we resort to a greedy algorithm for solving the cache content placement problem. Performance evaluation reveals that LECC can apparently improve content cache hit rate and decrease content delivery latency and transmission cost in comparison with known existing caching strategies. [ABSTRACT FROM AUTHOR]

Respiratory mitochondria undergo stochastic, intermittent bursts of superoxide production accompanied by transient depolarization of the mitochondrial membrane potential and reversible opening of the membrane permeability transition pore. These discrete events were named 'superoxide flashes' for the reactive oxygen species (ROS) signal involved, and 'mitochondrial flashes' (mitoflashes) for the entirety of the multifaceted and intertwined mitochondrial processes. In contrast to the flashless basal ROS production of 'homeostatic ROS' for redox regulation, bursting ROS production during mitoflashes may provide 'signalling ROS' at the organelle level, fulfilling distinctly different cell functions. Mounting evidence indicates that mitoflash frequency is richly regulated over a broad range, and represents a novel, universal, and 'digital' readout of mitochondrial functional status and of the mitochondrial stress response. An emerging view is that mitoflashes participate in vital processes including metabolism, cell differentiation, the stress response and ageing. These recent advances shed new light on the role of mitochondrial functional dynamics in health and disease. [ABSTRACT FROM AUTHOR]

Background: The longitudinal associations of sleep timing and time in bed (TIB) with dementia and cognitive decline in older adults are unclear. Methods: This population‐based cohort study used data from 1982 participants who were aged ≥60 years, free of dementia, and living in rural communities in western Shandong, China. At the baseline (2014) and follow‐up (2018) examinations, sleep parameters were assessed using standard questionnaires. Cognitive function was measured using the Mini‐Mental State Examination (MMSE). Dementia was diagnosed following the DSM‐IV criteria, and the NIA‐AA criteria for Alzheimer disease (AD). Data were analyzed using restricted cubic splines, Cox proportional‐hazards models, and general linear models. Results: During the mean follow‐up of 3.7 years, dementia was diagnosed in 97 participants (68 with AD). Restricted cubic spline curves showed J‐shaped associations of sleep duration, TIB, and rise time with dementia risk, and a reverse J‐shaped association with mid‐sleep time. When sleep parameters were categorized into tertiles, the multivariable‐adjusted hazard ratio (HR) of incident dementia was 1.69 (95%CI 1.01–2.83) for baseline sleep duration >8 hours (vs. 7–8 h), 2.17 (1.22–3.87) for bedtime before 9 p.m. (vs. 10 p.m. or later), and 2.00 (1.23–3.24) for mid‐sleep time before 1 a.m. (vs. 1–1.5 a.m.). Early bedtime and mid‐sleep time were significantly associated with incident AD (HR range: 2.25–2.51; p < 0.05). Among individuals who were free of dementia at follow‐up, baseline long TIB, early bedtime and mid‐sleep time, early and late rise time, and prolonged TIB and advanced bedtime and mid‐sleep time from baseline to follow‐up were associated with a greater decline in MMSE score (p < 0.05). These associations with cognitive decline were statistically evident mainly among men or participants who were aged 60–74 years. Conclusions: Long TIB and early sleep timing are associated with an increased risk of dementia, and the associations with greater cognitive decline are evident only among older people aged 60–74 years and men. [ABSTRACT FROM AUTHOR]

Keywords: grain boundary; N2 fixation; operando oxygen vacancies; photocatalysis; WO3 In article number 1902319, Xusheng Zheng, Shuquan Liang, Liangbing Wang, and co-workers report that grain boundaries (GBs) in nanoporous WO SB 3 sb induce many operando oxygen vacancies under light irradiation. Grain boundary, N2 fixation, operando oxygen vacancies, photocatalysis, WO3. [Extracted from the article]

Photocatalysts with oxygen vacancies (OVs) have exhibited exciting activity in N2 photofixation due to their superiority in capture and activation of N2. However, the surface OVs are easily oxidized by seizing the oxygen atoms from water or oxygen during the catalytic reaction. Here, it is reported that the grain boundaries (GBs) in nanoporous WO3 induce plenty of operando OVs under light irradiation to significantly boost catalytic activity toward N2 photofixation. Impressively, nanoporous WO3 with abundant GBs (WO3‐600) exhibit an ammonia production rate of 230 µmol gcat.−1 h−1 without any sacrificial agents at room temperature, 17 times higher than that for WO3 nanoparticles without GBs. Moreover, WO3‐600 also manifests remarkable stability by maintaining nearly ≈100% catalytic activity after ten successive reaction rounds. Further mechanistic studies reveal that both OVs and GBs regulate the band structures of WO3 nanocrystals, as well as favor the delivery of photogenerated electrons to adsorbed N2 by enhancing W–O covalency. More importantly, plenty of operando OVs induced by GBs generate during catalytic reaction, directly contributing to the excellent catalytic performance for WO3‐600. This work opens a novel avenue to developing efficient photocatalysts by construction of operando OVs. [ABSTRACT FROM AUTHOR]

Surveillance is an intricate challenge worldwide especially in those complicated environments such as nuclear plants, banks, crowded areas, barns, etc. Deploying self‐powered wireless sensor nodes can increase the system's event detection capabilities by collecting environmental changes, while the incompatibility among components (energy harvesters, sensors, and wireless modules) limits their application. Here, a broadly compatible self‐powered visualized platform (SPVP) is reported to construct a passive internet of events (IoE) network for surveillance systems. By encoding electric signals into reference and working LEDs, SPVP can visualize resistance change generated by commercial resistive sensors with a broad working range (<107 Ω) and the transmission distance is up to 30 meters. Visible light signals are captured by surveillance cameras and processed by the cloud to achieve real‐time event monitoring and identification, which forms the passive IoE network. It is demonstrated that the passive‐IoE‐based surveillance system can detect intrusion, theft, fire alarm, and distress signals quickly (30 ms) for 106 cycles. Moreover, the confidential information can be encrypted by SPVPs and accessed through a phone application. This universal scheme may have huge potential for the construction of safe and smart cities. [ABSTRACT FROM AUTHOR]

The breakdown of the blood–brain barrier, which develops early in Alzheimer's disease (AD), contributes to cognitive impairment. Exercise not only reduces the risk factors for AD but also confers direct protection against cognitive decline. However, the exact molecular mechanisms remain elusive, particularly whether exercise can liberate the function of the blood–brain barrier. Here, we demonstrate that long‐term exercise promotes the clearance of brain amyloid‐β by improving the function of the blood–brain barrier in 5XFAD mice. Significantly, treating primary brain pericytes or endothelial cells with exosomes isolated from the brain of exercised 5XFAD mice improves cell proliferation and upregulates PDGFRβ, ZO‐1, and claudin‐5. Moreover, exosomes isolated from exercised mice exhibit significant changes in miR‐532‐5p. Administration or transfection of miR‐532‐5p to sedentary mice or primary brain pericytes and endothelial cells reproduces the improvement of blood–brain barrier function. Exosomal miR‐532‐5p targets EPHA4, and accordingly, expression of EphA4 is decreased in exercised mice and miR‐532‐5p overexpressed mice. A specific siRNA targeting EPHA4 recapitulates the effects on blood–brain barrier‐associated cells observed in exercised 5XFAD mice. Overall, our findings suggest that exosomes released by the brain contain a specific miRNA that is altered by exercise and has an impact on blood–brain barrier function in AD. [ABSTRACT FROM AUTHOR]

Background and purpose: Little is known about whether nonalcoholic fatty liver disease (NAFLD) is associated with dementia or the role of serum proinflammatory cytokines in the association. We aimed to investigate the interrelationships of NAFLD, serum cytokines, and dementia among rural‐dwelling older adults. Methods: This population‐based cross‐sectional study included 5129 participants (aged ≥60 years; 61.79% women) who were living in rural communities and examined in March 2018–September 2018. NAFLD was defined through transabdominal ultrasound examination in the absence of hepatitis B or excessive alcohol consumption. Serum cytokines were measured in a subsample (n = 1686). Dementia, Alzheimer disease (AD), and vascular dementia (VaD) were diagnosed following international criteria. Data were analyzed with logistic regression and mediation models. Results: Of the 5129 participants, 455 (8.87%) were detected with moderate‐to‐severe NAFLD, and 292 (5.69%) were diagnosed with dementia (188 with AD and 96 with VaD). The multivariable adjusted odds ratios associated with moderate‐to‐severe (vs. no‐to‐mild) NAFLD were 2.22 (95% confidence interval [CI] = 1.41–3.49) for all‐cause dementia, 1.88 (95% CI = 1.01–3.50) for AD, and 2.62 (95% CI = 1.33–5.17) for VaD. In the cytokine subsample, controlling for multiple potential confounders, moderate‐to‐severe NAFLD was significantly associated with higher levels of serum monocyte chemotactic protein‐1, interleukin‐17A, interleukin‐6 (IL‐6), interleukin‐8, and tumor necrosis factor‐α (P < 0.05). The mediation analysis showed that IL‐6 mediated 12.56% of the association between NAFLD and VaD. Conclusions: Moderate‐to‐severe nonalcoholic fatty liver disease is associated with dementia and AD, especially with VaD, among rural‐dwelling Chinese older adults, in which the association with VaD is partly mediated by serum inflammatory cytokines. [ABSTRACT FROM AUTHOR]

Background: Olfactory impairment is associated with dementia in clinical settings. We examined the relationship of olfactory identification function with all‐cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD) and assessed the discriminative ability of the Sniffin' Sticks Identification Test (SSIT), the self‐rated Ascertain Dementia 8‐item Questionnaire (AD8), and their combination for dementia detection among rural‐dwelling older adults in China. Methods: This population‐based cross‐sectional study included 4481 participants (age ≥ 65 years; 56.8% women; 38.1% illiteracy) living in rural communities. The 16‐item SSIT was performed to assess olfactory identification function. The self‐rated AD8 was administered to participants for cognitive status. We diagnosed dementia, AD, and VaD following the international criteria. Data were analyzed with logistic regression models and receiver operating characteristic curve. Results: Of the 4481 participants, dementia was diagnosed in 139 persons (3.1%), including 92 with AD and 42 with VaD. The SSIT score (range, 0–16) was associated with multiadjusted odds ratios of 0.83 (95% CI: 0.79–0.88) for dementia, 0.84 (0.79–0.90) for AD, and 0.79 (0.71–0.87) for VaD. The area under the curve for the discrimination between participants with and without dementia was 0.73 (95% CI: 0.69–0.77) for SSIT score ≤ 8 alone, 0.86 (0.82–0.89) for self‐rated AD8 score ≥ 3 alone, and 0.89 (0.86–0.92) for their combination using a logistic model. Conclusions: Olfactory impairment is a clinical marker for all‐cause dementia, AD, and VaD. The smell identification test, in combination with the brief self‐rated cognitive screening tool, is accurate for screening dementia among rural‐dwelling Chinese older adults with no or limited education. [ABSTRACT FROM AUTHOR]

Background and purpose: Current evidence supports the involvement of lipids in brain aging. A range of serum lipids is explored in association with brain structure and cognitive function amongst rural‐dwelling older adults. Methods: This population‐based cross‐sectional study included 184 rural‐dwelling adults (age ≥ 65 years, 39.1% women) in Shandong, China. In 2014–2016, data on demographics, lifestyle, health conditions and serum lipids were collected. Volumes of gray matter, white matter, ventricles, hippocampus and white matter hyperintensity were automatically estimated on brain magnetic resonance imaging. Global cognitive function was assessed with the Mini‐Mental State Examination (MMSE), and mild cognitive impairment (MCI) was defined according to Petersen's criteria. Data were analyzed using the general linear regression, logistic regression and mediation models. Results: Of the 184 participants, 47 were defined with MCI. Low high‐density lipoprotein cholesterol (HDL‐C; <1.55 vs. ≥1.55 mmol/l) was significantly associated with reduced volumes of total white matter (multi‐adjusted β = −9.77, 95% confidence interval −19.48–0.06) and hippocampus (−0.23, −0.46–0.01), a lower MMSE score (−1.49, −2.67–0.31) and a higher likelihood of MCI (multi‐adjusted odds ratio 3.21, 95% confidence interval 1.42–7.29). The mediation effects of structural brain measures on the associations between a low level of HDL‐C and MMSE score or MCI were not statistically significant (p > 0.05). Conclusions: This study suggests that low HDL‐C may be involved in structural brain aging and cognitive dysfunction amongst rural‐dwelling older adults in China, but the association of low HDL‐C with cognitive aging phenotypes appears not to be mediated by brain structure. [ABSTRACT FROM AUTHOR]

Aim: A simple approach to detecting dementia in its early stages may help improve patient care. We therefore aimed to assess the power of the Functional Activities Questionnaire (FAQ) for screening dementia among rural‐dwelling older adults who are at high‐risk for cognitive impairment. Methods: This study included 961 participants at a high‐risk for dementia who had been identified from a population‐based survey of Chinese rural residents. All participants were aged 65 years and older and positive for cognitive impairment according to the Mini‐Mental State Examination or the Ascertain Dementia 8‐item Informant Questionnaire screening tests. The FAQ scale was used to evaluate daily activities. Dementia was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, criteria. Receiver operating characteristic curve analyses were used to determine the FAQ's optimal cut‐offs for dementia. The power (or accuracy) of the FAQ for screening dementia was analyzed in the total sample and in subgroups categorized by age, gender, and educational level. Results: Of the 961 participants, 84 (8.7%) were clinically diagnosed with dementia. Among individuals who were positive for cognitive impairment on the Mini‐Mental State Examination or the Ascertain Dementia 8‐item Informant Questionnaire, the parameters for an FAQ cut‐off score ≥6 as a means of discriminating those with dementia from those without dementia were area under curve = 0.899, sensitivity = 94.1%, specificity = 75.1%, positive likelihood ratio = 3.78, and accuracy = 0.768. The discriminant abilities of the FAQ scale varied with age, gender, and educational level. The discriminant parameters of the FAQ scale were similar overall among individuals who were positive on either the Mini‐Mental State Examination or the Ascertain Dementia 8‐item Informant Questionnaire test alone. Conclusion: The FAQ scale has high discriminative power to screen for dementia among rural older residents with suspected cognitive impairment. [ABSTRACT FROM AUTHOR]