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Regional severe haze represents an enormous environmental problem in China, influencing air quality, human health, ecosystem, weather, and climate. These extremes are characterized by exceedingly high concentrations of fine particulate matter (smaller than 2.5 μm, or PM2.5) and occur with extensive temporal (on a daily, weekly, to monthly timescale) and spatial (over a million square kilometers) coverage. Although significant advances have been made in field measurements, model simulations, and laboratory experiments for fine PM over recent years, the causes for severe haze formation have not yet to be systematically/comprehensively evaluated. This review provides a synthetic synopsis of recent advances in understanding the fundamental mechanisms of severe haze formation in northern China, focusing on emission sources, chemical formation and transformation, and meteorological and climatic conditions. In particular, we highlight the synergetic effects from the interactions between anthropogenic emissions and atmospheric processes. Current challenges and future research directions to improve the understanding of severe haze pollution as well as plausible regulatory implications on a scientific basis are also discussed.

BackgroundVegetarian diets may promote weight loss, but evidence remains inconclusive.MethodsPubMed, EMBASE and UpToDate databases were searched through September 22, 2014, and investigators extracted data regarding study characteristics and assessed study quality among selected randomized clinical trials. Population size, demographic (i.e., gender and age) and anthropometric (i.e., body mass index) characteristics, types of interventions, follow-up periods, and trial quality (Jadad score) were recorded. The net changes in body weight of subjects were analyzed and pooled after assessing heterogeneity with a random effects model. Subgroup analysis was performed based on type of vegetarian diet, type of energy restriction, study population, and follow-up period.ResultsTwelve randomized controlled trials were included, involving a total of 1151 subjects who received the intervention over a median duration of 18 weeks. Overall, individuals assigned to the vegetarian diet groups lost significantly more weight than those assigned to the non-vegetarian diet groups (weighted mean difference, −2.02 kg; 95 % confidence interval [CI]: −2.80 to −1.23). Subgroup analysis detected significant weight reduction in subjects consuming a vegan diet (−2.52 kg; 95 % CI: −3.02 to −1.98) and, to a lesser extent, in those given lacto-ovo-vegetarian diets (−1.48 kg; 95 % CI: −3.43 to 0.47). Studies on subjects consuming vegetarian diets with energy restriction (ER) revealed a significantly greater weight reduction (−2.21 kg; 95 % CI: −3.31 to −1.12) than those without ER (−1.66 kg; 95 % CI: −2.85 to −0.48). The weight loss for subjects with follow-up of <1 year was greater (−2.05 kg; 95 % CI: −2.85 to −1.25) than those with follow-up of ≥1 year (−1.13 kg; 95 % CI: −2.04 to −0.21).ConclusionsVegetarian diets appeared to have significant benefits on weight reduction compared to non-vegetarian diets. Further long-term trials are needed to investigate the effects of vegetarian diets on body weight control.

Two extremely wet winters in 2015/16 and 2018/19 over Southeast China are compared in this study. South-to-north discrepancies appear in the spatial distribution of precipitation, with anomalous precipitation centered over the southeast coast in 2015/16 and the lower reaches of Yangtze River valley in 2018/19, respectively. Both instances of enhanced precipitation are ascribed mainly to warm and moist advection from the south, with transport in 2015/16 partly by a deepened India–Burma trough to the west, whereas with transport in 2018/19 mainly by a subtropical western North Pacific anticyclone (WNPAC). Both the India–Burma trough and WNPAC are maintained by the wave trains propagating along the South Asian jet, which are zonally offset by a quarter-wavelength. Further study of the wave train sources in 2015/16 and 2018/19 shows that they both tend to originate from extremely strong storm-track activity over the North Atlantic but have different displacement. The former is located more northeastward than the mean storm track and is modulated by a strong positive NAO, whereas the latter lies over the midlatitude central North Atlantic along with a circumglobal teleconnection. These differences further result in a quarter-wavelength offset in the Rossby wave source near the entrance of the South Asian jet by the convergence of upper-level divergent wind.

In recent years, severe haze events often occurred in China, causing serious environmental problems. The mechanisms responsible for the haze formation, however, are still not well understood, hindering the forecast and mitigation of haze pollution. Our study of the 2012–13 winter haze events in Beijing shows that atmospheric water vapour plays a critical role in enhancing the heavy haze events. Under weak solar radiation and stagnant moist meteorological conditions in winter, air pollutants and water vapour accumulate in a shallow planetary boundary layer (PBL). A positive feedback cycle is triggered resulting in the formation of heavy haze: (1) the dispersal of water vapour is constrained by the shallow PBL, leading to an increase in relative humidity (RH); (2) the high RH induces an increase of aerosol particle size by enhanced hygroscopic growth and multiphase reactions to increase particle size and mass, which results in (3) further dimming and decrease of PBL height, and thus further depressing of aerosol and water vapour in a very shallow PBL. This positive feedback constitutes a self-amplification mechanism in which water vapour leads to a trapping and massive increase of particulate matter in the near-surface air to which people are exposed with severe health hazards.

Physiological signal processing plays a key role in next-generation human-machine interfaces as physiological signals provide rich cognition- and health-related information. However, the explosion of physiological signal data presents challenges for traditional systems. Here, we propose a highly efficient neuromorphic physiological signal processing system based on VO 2 memristors. The volatile and positive/negative symmetric threshold switching characteristics of VO 2 memristors are leveraged to construct a sparse-spiking yet high-fidelity asynchronous spike encoder for physiological signals. Besides, the dynamical behavior of VO 2 memristors is utilized in compact Leaky Integrate and Fire (LIF) and Adaptive-LIF (ALIF) neurons, which are incorporated into a decision-making Long short-term memory Spiking Neural Network. The system demonstrates superior computing capabilities, needing only small-sized LSNNs to attain high accuracies of 95.83% and 99.79% in arrhythmia classification and epileptic seizure detection, respectively. This work highlights the potential of memristors in constructing efficient neuromorphic physiological signal processing systems and promoting next-generation human-machine interfaces. Next-generation human-machine interfaces require efficient physiological signal processing systems. Here, the authors propose a hardware system that uses VO 2 memristors to perform brain-like encoding and analysis of physiological signals, and is capable of identifying arrhythmia and epileptic seizures.

The impact of brown carbon aerosol (BrC) on the Earth's radiative forcing balance has been widely recognized but remains uncertain, mainly because the relationships among BrC sources, chromophores and optical properties of aerosol are poorly understood. In this work, the light absorption properties and chromophore composition of BrC were investigated for samples collected in Xi'an, northwestern China, from 2015 to 2016. Both absorption Ångström exponent (AAE) and mass absorption efficiency (MAE) show distinct seasonal differences, which could be attributed to the differences in sources and chromophore composition of BrC. Three groups of light-absorbing organics were found to be important BrC chromophores, including compounds that have multiple absorption peaks at wavelengths > 350 nm (12 polycyclic aromatic hydrocarbons and their derivatives) and compounds that have a single absorption peak at wavelengths < 350 nm (10 nitrophenols and nitrosalicylic acids and 3 methoxyphenols). These measured BrC chromophores show distinct seasonal differences and contribute on average about 1.1 % and 3.3 % of light absorption of methanol-soluble BrC at 365 nm in summer and winter, respectively, about 7 and 5 times higher than the corresponding carbon mass fractions in total organic carbon. The sources of BrC were resolved by positive matrix factorization (PMF) using these chromophores instead of commonly used non-light-absorbing organic markers as model inputs. Our results show that vehicular emissions and secondary formation are major sources of BrC (∼ 70 %) in spring, coal combustion and vehicular emissions are major sources (∼ 70 %) in fall, biomass burning and coal combustion become major sources (∼ 80 %) in winter, and secondary BrC dominates (∼ 60 %) in summer.

Inflammation and fibrosis are two pathological features of chronic kidney disease (CKD). Transforming growth factor-β (TGF-β) has been long considered as a key mediator of renal fibrosis. In addition, TGF-β also acts as a potent anti-inflammatory cytokine that negatively regulates renal inflammation. Thus, blockade of TGF-β inhibits renal fibrosis while promoting inflammation, revealing a diverse role for TGF-β in CKD. It is now well documented that TGF-β1 activates its downstream signaling molecules such as Smad3 and Smad3-dependent non-coding RNAs to transcriptionally and differentially regulate renal inflammation and fibrosis, which is negatively regulated by Smad7. Therefore, treatments by rebalancing Smad3/Smad7 signaling or by specifically targeting Smad3-dependent non-coding RNAs that regulate renal fibrosis or inflammation could be a better therapeutic approach. In this review, the paradoxical functions and underlying mechanisms by which TGF-β1 regulates in renal inflammation and fibrosis are discussed and novel therapeutic strategies for kidney disease by targeting downstream TGF-β/Smad signaling and transcriptomes are highlighted.

The ability to detect low numbers of microbial cells in food and clinical samples is highly valuable but remains a challenge. Here we present a detection system (called ‘APC-Cas’) that can detect very low numbers of a bacterial pathogen without isolation, using a three-stage amplification to generate powerful fluorescence signals. APC-Cas involves a combination of nucleic acid-based allosteric probes and CRISPR-Cas13a components. It can selectively and sensitively quantify Salmonella Enteritidis cells (from 1 to 10 5 CFU) in various types of samples such as milk, showing similar or higher sensitivity and accuracy compared with conventional real-time PCR. Furthermore, APC-Cas can identify low numbers of S . Enteritidis cells in mouse serum, distinguishing mice with early- and late-stage infection from uninfected mice. Our method may have potential clinical applications for early diagnosis of pathogens. The detection of pathogens in food and clinical samples remains a challenge. Here, Shen et al. present a detection system, involving a combination of nucleic acid-based allosteric probes and CRISPR-Cas13a components, that can detect very low numbers of a bacterial pathogen in milk and serum samples without isolation.

MicroRNAs (miRNAs) have been widely investigated as potential biomarkers for early clinical diagnosis of cancer. Developing an miRNA detection platform with high specificity, sensitivity, and exploitability is always necessary. Electrochemiluminescence (ECL) is an electrogenerated chemiluminescence technology that greatly decreases background noise and improves detection sensitivity. The development of a paper‐based ECL biosensor further makes ECL suitable for point‐of‐care detection. Recently, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas13a as high‐fidelity, efficient, and programmable CRISPR RNA (crRNA) guided RNase has brought a next‐generation biosensing technology. However, existing CRISPR/Cas13a based detection often faces a trade‐off between sensitivity and specificity. In this research, a CRISPR/Cas13a powered portable ECL chip (PECL‐CRISPR) is constructed. Wherein target miRNA activates Cas13a to cleave a well‐designed preprimer, and triggers the subsequent exponential amplification and ECL detection. Under optimized conditions, a limit‐of‐detection of 1 × 10−15 m for miR‐17 is achieved. Through rationally designing the crRNA, the platform can provide single nucleotide resolution to dramatically distinguish miRNA target from its highly homologous family members. Moreover, the introduction of “light‐switch” molecule [Ru(phen)2dppz]2+ allows the platform to avoid tedious electrode modification and washing processes, thereby simplifying the experimental procedure and lower testing cost. Analysis results of miRNA from tumor cells also demonstrate the PECL‐CRISPR platform holds a promising potential for molecular diagnosis. A clustered regularly interspaced short palindromic repeats (CRISPR)/Cas13a powered portable pBPE‐ECL chip (PECL‐CRISPR) is developed, which combines the high‐fidelity and trans‐cleavage of Cas13a, high efficiency of exponential amplification, high sensitivity and low background noise of electrochemiluminescence technology, and the simplicity of “light‐switch” [Ru(phen)2dppz]2+, thereby enabling ultrasensitive, highly‐specific, convenient, and low‐cost detection of miRNA.

Sea spray aerosols (SSAs) make up a substantial proportion of aerosols in the global atmosphere and, especially when considering marine haze and cloud layers, can have a large impact on cloud formation and atmospheric radiative balance. Although SSA has the highest cloud condensation nuclei (CCN) activation potential, the majority of its population, residing in sub-micrometre sizes, are often obscured by non-sea-spray CCN. Quantification of SSA-derived CCN is fundamental in understanding the radiative budget. Recent approaches to estimate the sub-micrometre SSA employed a free-monomodal lognormal analysis that depicts the global oceanic CCN population comprising less than 30% SSA. Here we derive SSA distributions from a unique five-year dataset of aerosol microphysics and hygroscopicity (water uptake ability) over Atlantic waters. This approach utilizes the distinctive ultra-high hygroscopicity signature of inorganic sea salt and is able to identify the sub-micrometre sea spray down to 35 nm diameter with high time and size resolution. In stark contrast to previous studies, the hygroscopicity coupled multimodal fitting analysis yields SSA-derived CCN as much as 500% in excess of estimates produced using the free-monomodal approach. Our results suggest the contribution of SSA to global CCN, particularly Aitken mode SSA, has probably been overlooked. Very small aerosols from sea spray make up a larger proportion of cloud condensation nuclei than previously recognized, according to an analysis of five years of aerosol ground-based measurement data from over the Atlantic Ocean.