Abstract
Severe events of wintertime particulate air pollution in Beijing (winter haze) are associated with high relative humidity (RH) and fast production of particulate sulfate from the oxidation ...of sulfur dioxide (SO
2
) emitted by coal combustion. There has been considerable debate regarding the mechanism for SO
2
oxidation. Here we show evidence from field observations of a haze event that rapid oxidation of SO
2
by nitrogen dioxide (NO
2
) and nitrous acid (HONO) takes place, the latter producing nitrous oxide (N
2
O). Sulfate shifts to larger particle sizes during the event, indicative of fog/cloud processing. Fog and cloud readily form under winter haze conditions, leading to high liquid water contents with high pH (>5.5) from elevated ammonia. Such conditions enable fast aqueous-phase oxidation of SO
2
by NO
2
, producing HONO which can in turn oxidize SO
2
to yield N
2
O.This mechanism could provide an explanation for sulfate formation under some winter haze conditions.
Mitochondrial NAD+‐dependent protein deacetylase Sirtuin3 (SIRT3) has been proposed to mediate calorie restriction (CR)‐dependent metabolic regulation and lifespan extension. Here, we investigated ...the role of SIRT3 in CR‐mediated longevity, mitochondrial function, and aerobic fitness. We report that SIRT3 is required for whole‐body aerobic capacity but is dispensable for CR‐dependent lifespan extension. Under CR, loss of SIRT3 (Sirt3−/−) yielded a longer overall and maximum lifespan as compared to Sirt3+/+ mice. This unexpected lifespan extension was associated with altered mitochondrial protein acetylation in oxidative metabolic pathways, reduced mitochondrial respiration, and reduced aerobic exercise capacity. Also, Sirt3−/−CR mice exhibit lower spontaneous activity and a trend favoring fatty acid oxidation during the postprandial period. This study shows the uncoupling of lifespan and healthspan parameters (aerobic fitness and spontaneous activity) and provides new insights into SIRT3 function in CR adaptation, fuel utilization, and aging.
This study shows that lifespan and healthspan parameters can be uncoupled and that the mitochondrial protein SIRT3 is a modulator of fuel utilization, physical activity, and aging.
•Comprehensive TEM/STEM and micro-Raman characterization were performed.•Quantitative analyses were carried out on STEM-based images.•The loss of carbon packets and SiC grain growth occurred ...simultaneously in fibers.•A grain growth theory based mechanism was proposed to explain the above result.
Amosic-3 SiC/SiC composites were irradiated at 300 °C using 6 MeV Si ions to peak doses of 13 and 55 displacements per atom (dpa). The loss of amorphous carbon packets and the growth of SiC grains were simultaneously observed in Amosic-3 SiC fibers, using a combination of transmission electron microscopy (TEM) and Raman spectroscopy. A mechanism based on the grain growth theory was proposed to expound the relationship between the loss of carbon packets and the growth of SiC grains. Small and curved SiC grains can absorb surrounding carbon packets to grow themselves; at some point, these grains further grow at the expense of adjacent small SiC grains until their grain boundary became straight. TEM images were found to support the above mechanism.
•Soil water characteristic curve (SWCC) with residual plastic-film was experimented.•A SWCC model for soil with residual plastic-film (RPF-SWCC) was firstly proposed.•The comparisons were carried out ...between RPF-SWCC and other SWCC models.•The RPF-SWCC had higher fitting accuracy for the soil with residual plastic-film.
Although plastic-film mulching has played an important role in agriculture production in arid areas, the practice has resulted in the accumulation of large amounts of residual plastic film (RPF) in the soil. This intensely impedes the movement of the water and solutes in soil by seriously affecting the physical and hydraulic properties of soil, in particular the soil water characteristic curve (SWCC). Despite the severity of the problem, studies on how RPF affects soil properties and the SWCC remain scarce. This paper thus aims to achieve a better understanding of the influences of RPF on soil pores and SWCC. In this study, SWCCs were measured under five concentrations of RPF (0 kg·hm−2, 50 kg·hm−2, 100 kg·hm−2, 200 kg·hm−2 and 400 kg·hm−2) and three soil textures (sandy soil, sandy loam and loam soil) based on the pressure plate extractor test. A model for estimating SWCC for soil with residual plastic film (RPF-SWCC) based on an improved pore-size distribution is proposed, and its performance was evaluated and compared with those for existing models, including the van Genuchten (VG), Brooks-Corey (BC) and log normal distribution (LND) models. The results showed that there is a clear influence by the RPF in soil on the shape of the SWCC, and the order of the different soil types in regards to soil water holding capacity was loam soil > sandy loam > sandy soil, with or without RPF. The RPF-SWCC model accounted for the effects of water blocking by RPF, thereby achieving improved fitting accuracy compared to that by the VG, BC and LND models, especially for soil with high RPF concentration. The average Nash-Sutcliffe efficiency coefficient (NSE), mean absolute percentage error (MAPE) and symmetric mean absolute percentage error (SMAPE) for achieved for the RPF-SWCC model were 0.9943, 3.37% and 3.43%, respectively, which was an improvement on the 0.9938, 5.94% and 5.06% achieved for the VG model, 0.9926, 4.43% and 4.25% for the BC model and 0.9923, 15.00% and 7.53% for the LND model, respectively. In addition, the correlation between the parameters of the RPF-SWCC model and RPF concentration showed that the saturated soil water content and residual soil water content decreased and increased with increasing RPF concentration, respectively. In addition, soil RPF increased and decreased the proportion of macropores and soil water holding capacity, respectively. This study can provide a theoretical and technical basis for research into soil water movement and the efficient utilization of water and fertilizer in areas with high agricultural film residue.
Mitochondria are vital organelles in cells, regulating energy metabolism and apoptosis. Mitochondrial transcellular transfer plays a crucial role during physiological and pathological conditions, ...such as rescuing recipient cells from bioenergetic deficit and tumorigenesis. Studies have shown several structures that conduct transcellular transfer of mitochondria, including tunneling nanotubes (TNTs), extracellular vesicles (EVs), and Cx43 gap junctions (GJs). The intra- and intercellular transfer of mitochondria is driven by a transport complex. Mitochondrial Rho small GTPase (MIRO) may be the adaptor that connects the transport complex with mitochondria, and myosin XIX is the motor protein of the transport complex, which participates in the transcellular transport of mitochondria through TNTs. In this review, the roles of TNTs, EVs, GJs, and related transport complexes in mitochondrial transcellular transfer are discussed in detail, as well as the formation mechanisms of TNTs and EVs. This review provides the basis for the development of potential clinical therapies targeting the structures of mitochondrial transcellular transfer.
Electrocatalytic hydrogenation (ECH) has been used as a novel approach for the synthesis of organic compounds. Hence, ZIF-67 was selected as a precursor in this study to synthesize a series of ...electrodes. The ECH effects were assessed on pyridine and diazines. The results showed a significant influence of carbonization temperature and time on the electrocatalyst activity. A temperature of 400 °C was found not high enough for the synthesis of the electrocatalysts, and a long time of 4 h at 800 °C resulted in damage to the spatial structure of the electrocatalyst. The optimal electrocatalyst was obtained under 800 °C and 2 h (Co/NC-800–2). The polyhedral Co/NC-800–2 (20–200 nm) had the N-doped graphitic-carbon shell with embedded Co/CoN/Co3O4 nanoparticles. The onset potential and overpotential (at 10 mA cm−2) were estimated to respectively 64 and 155 mV versus hydrogen evolution reaction (HER), with a Tafel value of 62 mV dec−1. The ECH on pyridine and diazines revealed a positive correlation between ECH effect and HER activity. Co/NC-800–2 possessed excellent ECH activity toward pyridine and pyrazine at − 0.3 V (vs. RHE). N–Co, pyridinic-N, and graphitic-N acted as active sites during electrocatalysis. The N-doped graphitic-carbon promoted the charge transfer during ECH processes.
•The carbonation conditions significantly affected ZIF-67-derived electrodes activity.•The optimal HER activity electrocatalyst was obtained at 800 °C and 2 h.•The hydrogenation behavior of electrode for pyridine was similar to the HER activity.•Co/NC-800–2 showed admirable electrocatalytic hydrogenation of pyridine and diazines.•The efficient catalytic mechanism of Co/NC-800–2 was proposed.
Secondary organic aerosol (SOA) produced by atmospheric oxidation of primary emitted precursors is a major contributor to fine particulate matter (PM
) air pollution worldwide. Observations during ...winter haze pollution episodes in urban China show that most of this SOA originates from fossil-fuel combustion but the chemical mechanisms involved are unclear. Here we report field observations in a Beijing winter haze event that reveal fast aqueous-phase conversion of fossil-fuel primary organic aerosol (POA) to SOA at high relative humidity. Analyses of aerosol mass spectra and elemental ratios indicate that ring-breaking oxidation of POA aromatic species, leading to functionalization as carbonyls and carboxylic acids, may serve as the dominant mechanism for this SOA formation. A POA origin for SOA could explain why SOA has been decreasing over the 2013-2018 period in response to POA emission controls even as emissions of volatile organic compounds (VOCs) have remained flat.
Actin is the structural protein of microfilaments, and it usually exists in two forms: monomer and polymer. Among them, monomer actin is a spherical molecule composed of a polypeptide chain, also ...known as spherical actin. The function of actin polymers is to produce actin filaments, so it is also called fibroactin. The actin cytoskeleton is considered to be an important subcellular filament system. It interacts with numerous relevant proteins and regulatory cells, regulating basic functions, from cell division and muscle contraction to cell movement and ensuring tissue integrity. The dynamic reorganization of the actin cytoskeleton has immense influence on the progression and metastasis of cancer as well. This paper explores the significance of the microfilament network, the dynamic changes of its structure and function in the presence of a tumor, the formation process around the actin system, and the relevant proteins that may be target molecules for anticancer drugs so as to provide support and reference for interlinked cancer treatment research in the future.
Developing a new generation of anticancer metal-based drugs that can both kill tumor cells and inhibit cell migration is a promising strategy. Herein, we synthesized three Cu(II), Zn(II), and Mn(II) ...complexes derived from 5-chloro-2-
-(2-quinolylmethylene)aminophenol (C1-C3). Among these complexes, the Cu(II) complex (C1) showed significantly greater cytotoxicity toward lung cancer cell lines than cisplatin. C1 inhibited A549 cell metastasis and suppressed the growth of the A549 tumor in vivo. In addition, we confirmed the anticancer mechanism of C1 by triggering multiple mechanisms, including inducing mitochondrial apoptosis, acting on DNA, blocking cell cycle arrest, inducing cell senescence, and inducing DNA damage.
Non-alcoholic fatty liver disease (NAFLD) has a global prevalence of approximately 25 % and is associated with high morbidity and high mortality. NAFLD is a leading cause of cirrhosis and ...hepatocellular carcinoma. Its pathophysiology is complex and still poorly understood, and there are no drugs used in the clinic to specifically treat NAFLD. Its pathogenesis involves the accumulation of excess lipids in the liver, leading to lipid metabolism disorders and inflammation. Phytochemicals with the potential to prevent or treat excess lipid accumulation have recently received increasing attention, as they are potentially more suitable for long-term use than are traditional therapeutic compounds. In this review, we summarize the classification, biochemical properties, and biological functions of flavonoids and how they are used in the treatment of NAFLD. Highlighting the roles and pharmacological uses of these compounds will be of importance for enhancing the prevention and treatment of NAFLD.
Display omitted
PDF
