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While carboxylic acids are important components in both particle and gas phases in the atmosphere, their sources and partitioning are not fully understood. In this study, we present real-time measurements of both particle- and gas-phase concentrations for five of the most common and abundant low-molecular-weight carboxylic acids (LMWCA) in a rural region in the southeastern U.S. in Fall 2016. Through comparison with secondary organic aerosol (SOA) tracers, we find that isoprene was the most important local precursor for all five LMWCA but via different pathways. We propose that monocarboxylic acids (formic and acetic acids) were mainly formed through gas-phase photochemical reactions, while dicarboxylic acids (oxalic, malonic, and succinic acids) were predominantly from aqueous processing. Unexpectedly high concentrations of particle-phase formic and acetic acids (in the form of formate and acetate, respectively) were observed and likely the components of long-range transport organic aerosol (OA), decoupled from their gas-phase counterparts. In addition, an extraordinarily strong correlation (R2 = 0.90) was observed between a particulate LMWCA and aged SOA, which we tentatively attribute to boundary layer dynamics.

Reaumuria trigyna, an endangered recretohalophyte, is a small archaic wild shrub endemic to arid and semiarid plateau regions of Inner Mongolia, China. Based on salt-related transcriptomic data, we isolated a GRX family gene, glutaredoxin like protein (RtGRL1), from R. trigyna that is associated with the removal of active oxygen and regulation of redox status. RtGRL1 encodes a plasma membrane and chloroplast-localized protein induced by salt, cold, drought stress, ABA, and H2O2. In Arabidopsis thaliana, ectopically expressed RtGRL1 positively regulated biomass accumulation, chlorophyll content, germination rate, and primary root length under salt and drought stress. Overexpression of RtGRL1 induced expression of genes related to antioxidant enzymes and proline biosynthesis, thus increasing glutathione biosynthesis, glutathione-dependent detoxification of reactive oxygen species (ROS), and proline content under stress. Changes in RtGRL1 expression consistently affected glutathione/oxidizedglutathione and ascorbate/dehydroascorbate ratios and H2O2 concentrations. Furthermore, RtGRL1 promoted several GSH biosynthesis gene transcripts, decreased leaf Na+ content, and maintained lower Na+/K+ ratios in transgenic A. thaliana compared to wild type plants. These results suggest a critical link between RtGRL1 and ROS modulation, and contribute to a better understanding of the mechanisms governing plant responses to drought and salt stress.

Acanthopanax senticosus (Ciwujia) has broad-spectrum pharmacological activities, including osteoprotective effects. However, the mechanisms underlying these effects remain unclear. We investigated whether Acanthopanax senticosus aqueous extract (ASAE) ameliorates ovariectomy-induced bone loss in middle-aged mice through inhibition of osteoclastogenesis. In vitro, ASAE significantly suppressed the receptor activator of nuclear factor-κB ligand (RANKL)-stimulated osteoclast differentiation and formation of F-actin rings by downregulating the expression of the nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), c-Fos, and osteoclastogenesis-related marker genes and proteins, including c-Src, tartrate-resistant acid phosphatase (TRAP), cathepsin K, β3-integrin, and matrix metallopeptidase-9 (MMP-9). This was achieved by inhibiting RANK signaling pathways, including p65, c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38 in osteoclast precursors. In vivo, ASAE markedly ameliorated bone loss in ovariectomized (OVX) middle-aged mice. ASAE significantly inhibited the serum levels of tartrate-resistant acid phosphatase 5b (TRACP-5b) and RANKL, whereas it increased those of osteocalcin, procollagen 1 N-terminal peptide (P1NP), and osteoprotegerin in OVX mice. ASAE significantly inhibited the OVX-induced expression of osteoclast-specific proteins and genes in the femur. In conclusion, ASAE prevents ovariectomy-induced bone loss in middle-aged mice by inhibiting RANKL-induced osteoclastogenesis through suppression of RANK signaling pathways and could be potentially used in mediated treatment of osteoclast-related diseases (e.g., osteoporosis).

Efficient utilization of crop residues can help to solve the problem of global resource scarcity. The pyrolysis and combustion characteristics of 40 crop residues and 3 lignocellulosic components in different atmospheres by thermogravimetric analysis were analyzed. The results showed that with the increase of heating rate, the pyrolysis and combustion of cellulose, hemicelluloses, lignin and crop residues shifted to higher temperature zones. Meanwhile, the comprehensive combustibility index increased significantly, indicating that a higher heating rate could intensify and improve the pyrolysis and combustion performances. At the heating rate of 20 °C/min, the variation ranges of ignition temperatures of crop residues in N2, air and O2 were 253–295 °C, 247–275 °C and 245–268 °C, and the variation ranges of burnout temperatures were 555–682 °C, 466–596 °C and 323–357 °C, respectively. The comprehensive combustibility index in O2 was 144.24 × 10−7, which were much higher than those in air and N2. The variation ranges of activation energies of crop residues were 25.52–36.84, 27.96–43.35 and 41.07–69.35 kJ/mol in N2, air and O2 at 20 °C/min, respectively, and the combustion of crop residues in O2 is the most intense. Overall, rape stalk showed the best comprehensive pyrolysis and combustion performance, and rice straw was the poorest.

In March and April 2020, the South Coast Air Basin of California (USA) experienced noticeable declines in on-road activity and primary traffic-related pollutant emissions. However, secondary ozone concentration trends were not consistent across the basin. This research letter explores the impact of meteorology and emissions during this time period. The study elucidates the potential impacts on ozone nonattainment status for the region.

Caffeine is chemically stable and not readily oxidized under normal physiological conditions but also has antioxidant effects, although the underlying molecular mechanism is not well understood. Superoxide dismutase (SOD) 2 is a manganese-containing enzyme located in mitochondria that protects cells against oxidative stress by scavenging reactive oxygen species (ROS). SOD2 activity is inhibited through acetylation under conditions of stress such as exposure to ultraviolet (UV) radiation. Sirtuin 3 (SIRT3) is the major mitochondrial nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase, which deacetylates two critical lysine residues (lysine 68 and lysine 122) on SOD2 and promotes its antioxidative activity. In this study, we investigated whether the antioxidant effect of caffeine involves modulation of SOD2 by SIRT3 using in vitro and in vivo models. The results show that caffeine interacts with SIRT3 and promotes direct binding of SIRT3 with its substrate, thereby enhancing its enzymatic activity. Mechanistically, caffeine bound to SIRT3 with high affinity (K D = 6.858 × 10-7 M); the binding affinity between SIRT3 and its substrate acetylated p53 was also 9.03 (without NAD+) or 6.87 (with NAD+) times higher in the presence of caffeine. Caffeine effectively protected skin cells from UV irradiation-induced oxidative stress. More importantly, caffeine enhanced SIRT3 activity and reduced SOD2 acetylation, thereby leading to increased SOD2 activity, which could be reversed by treatment with the SIRT3 inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP) in vitro and in vivo. Taken together, our results show that caffeine targets SIRT3 to enhance SOD2 activity and protect skin cells from UV irradiation-induced oxidative stress. Thus, caffeine, as a small-molecule SIRT3 activator, could be a potential agent to protect human skin against UV radiation.

A novel pretreatment process of corn stover was established in this study by in situ modification of lignin with poly (ethylene glycol) diglycidyl ether (PEGDE) during low temperature alkali pretreatment. The addition of PEGDE obviously improved the enzymatic hydrolysis by covalently modifying the residual lignins in substrates. Under the optimized conditions (pretreated with 10% (w/w) NaOH and 10% (w/w) PEGDE at 70°C for 2.5h), the total fermentable sugar yield was increased by 46.4%, from 23.7g to 34.7g per 100g raw materials. Additionally, the remaining activities of exo-glucanase and β-glucosidase in supernatant were increased by 58.6% and 40.6% respectively, demonstrating that the enhancement of enzymatic hydrolysis was mainly due to the alleviation of enzyme non-productive binding. Although the isolated lignin modified with PEGDE enhanced the enzymatic hydrolysis of substrates as well, this in situ lignin modification provided an efficient but simple way to improve enzymatic saccharification.

Reaumuria trigyna is an endangered recretohalophyte and a small archaic feral shrub that is endemic to arid and semi-arid plateau regions of Inner Mongolia, China. Based on transcriptomic data, we isolated a high-affinity potassium transporter gene (RtHKT1) from R. trigyna, which encoded a plasma membrane-localized protein. RtHKT1 was rapidly up-regulated by high Na+ or low K+ and exhibited different tissue-specific expression patterns before and after stress treatment. Transgenic yeast showed tolerance to high Na+ or low K+, while transgenic Arabidopsis exhibited tolerance to high Na+ and sensitivity to high K+, or high Na+-low K+, confirming that Na+ tolerance in transgenic Arabidopsis depends on a sufficient external K+ concentration. Under external high Na+, high K+ and low K+ conditions, transgenic yeast accumulated more Na+-K+, Na+ and K+, while transgenic Arabidopsis accumulated less Na+-more K+, more Na+ and more Na+-K+, respectively, indicating that the ion transport properties of RtHKT1 depend on the external Na+-K+ environment. Salt stress induced up-regulation of some ion transporter genes (AtSOS1/AtHAK5/AtKUP5-6), as well as down-regulation of some genes (AtNHX1/AtAVP1/AtKUP9-12), revealing that multi-ion-transporter synergism maintains Na+/K+ homeostasis under salt stress in transgenic Arabidopsis. Overexpression of RtHKT1 enhanced K+ accumulation and prevented Na+ transport from roots to shoots, improved biomass accumulation and Chl content in salt-stressed transgenic Arabidopsis. The proline content and relative water content increased significantly, and some proline biosynthesis genes (AtP5CS1 and AtP5CS2) were also up-regulated in salt-stressed transgenic plants. These results suggest that RtHKT1 confers salt tolerance on transgenic Arabidopsis by maintaining Na+/K+ homeostasis and osmotic homeostasis.

Size-resolved aerosols were continuously collected by a Nano Sampler for 13 days at an urban site in Beijing during winter 2012 to measure the chemical composition of ambient aerosol particles. Data collected by the Nano Sampler and an ACSM (Aerodyne Aerosol Chemical Speciation Monitor) were compared. Between the data sets, similar trends and strong correlations were observed, demonstrating the validity of the Nano Sampler. PM10 and PM2.5 concentrations during the measurement were 150.5 ± 96.0 μg/m3 (mean ± standard variation) and 106.9 ± 71.6 μg/m3, respectively. The PM2.5/PM10 ratio was 0.70 ± 0.10, indicating that PM2.5 dominated PM10. The aerosol size distributions showed that three size bins of 0.5–1, 1–2.5 and 2.5–10 μm contributed 21.8%, 23.3% and 26.0% to the total mass concentration (TMC), respectively. OM (organic matter) and SIA (secondary ionic aerosol, mainly SO42 −, NO3− and NH4+) were major components of PM2.5. Secondary compounds (SIA and secondary organic carbon) accounted for half of TMC (about 49.8%) in PM2.5, and suggested that secondary aerosols significantly contributed to the serious particulate matter pollution observed in winter. Coal burning, biomass combustion, vehicle emissions and SIA were found to be the main sources of PM2.5. Mass concentrations of water-soluble ions and undetected materials, as well as their fractions in TMC, strikingly increased with deteriorating particle pollution conditions, while OM and EC (elemental carbon) exhibited different variations, with mass concentrations slightly increasing but fractions in TMC decreasing.

Graphene-based Cr2O3 composites are prepared and exhibit better electrochemical properties than free Cr2O3 particles without the graphene. The synthesis procedure consists of the direct growth of CrOOH on the surface of graphene and the subsequent thermal decomposition of CrOOH to Cr2O3. Moreover, the electrochemical properties of graphene-based Cr2O3 are further improved through carbon coating, and two strategies are developed. Interestingly, the carbon layers pyrolyzed from glucose on CrOOH can separate the particles on the graphene and limit their growth, while those on Cr2O3 merely cover the particles and cannot prevent particle aggregation. Consequently, compared to the latter carbon-coated composite, the former shows further improved electrochemical behavior.

Graphene-based metal oxides commonly show outstanding electrochemical performance due to the superior properties of graphene. However, the as-formed metal oxides decorated on graphene prefer to disintegrate or aggregate together, and the graphene–metal oxide hybrids also randomly aggregate themselves, resulting in capacity fading and poor cycling stability. Herein, the graphene-based metal oxides are further protected by graphene nanosheets through a stepwise heterocoagulation method, producing a layered sandwich structure. Compared to the normal graphene-based metal oxides, the sandwich-like graphene-based composites exhibit higher reversible capacities, better cycle performances, and higher rate capabilities. Such sandwich structure can avoid the aggregation of the composites and also act as an ideal strain buffer to alleviate the volume change of metal oxides during cycles. Moreover, the electronic conductivity of the electrode can be further enhanced by the introduction of additional graphene nanosheets. This double layer protection strategy is very effective and may be extended to prepare other high-capacity electrode materials for lithium-ion batteries.