Fabrication of an Optoplasmonic Raft with Improved SERS Performance Detecting Methamphetamine through Bubble Enrichment.

In this work, a novel raft-like structure that combines noble metal nanoparticles (NPs) with an interconnected layer of hemispherical dielectric shell was fabricated and characterized. It was discovered that this hybrid material can enhance the optoplasmonic interaction between plasmonic and dielectric components, thereby improving the sensing performance in surface-enhanced Raman spectroscopy (SERS). Varied geometric parameters of the fabricated optoplasmonic raft, including the inner diameter and thickness of the dielectric shell, were attempted and analyzed through numerical simulation and experimental SERS measurements. With particular size, thickness, and incident orientation, the silica shell focuses the incident optical flow into the deposited silver NPs, undergoing similar near-field focusing behavior in comparison with other optoplasmonic entities. This optoplasmonic raft floating on the water surface is able to harvest the target molecules effectively through bubble enrichment, which rapidly captures and concentrates analytes from the aqueous phase. With a limited sampling time, the sensing performance of the developed optoplasmonic raft is improved by applying the optimized parameters involved in bubble enrichment. The substrates and corresponding enrichment method were implemented in the detection of methamphetamine (METH), achieving a limit of detection (LOD) down to 0.035 nM. As for practical onsite detection, the developed substrate and bubbling strategy were applied in an assembled set, employing a portable Raman spectrometer and an air pump. This set is able to detect METH dissolved in regular commercial beer, which is quite competent in the investigation of drug abuse.

Effects of aerosol water content and acidity on the light absorption of atmospheric humic-like substances in winter.

Atmospheric humic-like substances (HULIS) could affect regional climate due to their strong light-absorbing capacity. Daily fine particulate matter (PM2.5) samples were collected from December 18, 2016 to January 8, 2017 at an urban site in Chongqing, Southwest China. The mean concentration of HULIS in terms of carbon (HULIS-C) was 6.4 ± 3.4 µg m-3, accounting for 72% of water-soluble organic carbon. The mass absorption efficiency at 365 nm (MAE365) and absorption Ångström index (AAE) of atmospheric HULIS were 2.8 ± 0.30 m2 g-1 C and 4.6 ± 0.37, respectively. Good correlations between the light absorption coefficients of HULIS at 365 nm (Abs365) and the concentrations of K+, elemental carbon, NO3-, and NH4+ were observed, with correlation coefficients higher than 0.83, indicating that biomass burning and secondary formation were potential sources of light-absorbing HULIS, as evidenced by abundant fluorescent components related to less-oxygenated HULIS. Comparing the changes in Abs365 values, concentrations of major water-soluble inorganic ions and carbonaceous compounds in PM2.5, and environmental factors during the clean and pollution periods, we found that extensive biomass burning during the pollution period contributed significantly to the increase of Abs365 values. Moreover, the aerosol pH during the pollution period was close to 4, and NO2 concentration and aerosol water content were about 1.6 and 2.7 times higher than those during the clean period, respectively, which were favorable to form secondary HULIS through aqueous phase reactions in the presence of high NOx, resulting in an evident increase in its light absorption. Knowledge generated from this study is critical for evaluating the regional radiative forcing of brown carbon in southwest China.

Trends of inorganic sulfur and nitrogen species at an urban site in western Canada (2004-2018).

A 15-year (2004-2018) record of measurement data of gaseous and particulate sulfur and nitrogen pollutants in air collected at an urban site in Burnaby in western Canada was analyzed for generating their decadal trends using three different methods, including linear regression, Mann-Kendall test and Theil-Sen trend estimator (MK-TS), and ensemble empirical mode decomposition (EEMD). Annual mean concentration of SO2 and SO42- decreased by about 59% and 42%, respectively, during the 15-year period. The slower decreases of SO42- than SO2 were mainly caused by the increased O3 concentration and temperature in spring and summer, which promoted conversion of SO2 to SO42- through gas-phase reaction, and by the increased aerosol pH value and availability of H2O2 in winter, which enhanced aqueous-phase SO42- formation. Accordingly, the sulfur oxidation ratio (SOR) increased by 23% or more in spring, summer, and winter during the 15-year period. Annual mean concentrations of NO2 and NO3- declined by 36% and 38%, respectively, during this period. On seasonal basis, NO3- decreased faster than NO2 in autumn and slower in winter. The non-linear responses of NO3- to NO2 concentration decreases were more evident in winter than the other seasons, partly due to the increased particulate NO3- fraction caused by decreased temperature, increased aerosol pH value, and enhanced NO3- formation caused by increased O3 concentrations. Annual mean concentration of NH3 showed small increases due to stable NH3 emission and reduced conversion of NH3 to NH4+. NH4+ concentration decreased by 51% during the 15-year period. These results suggest that reduced oxidants levels are likely responsible for weakened formation of secondary inorganic aerosols, besides emission reductions for SO2 and NO2.

Hedgehog signaling regulates bone homeostasis through orchestrating osteoclast differentiation and osteoclast-osteoblast coupling.

Imbalance of bone homeostasis induces bone degenerative diseases such as osteoporosis. Hedgehog (Hh) signaling plays critical roles in regulating the development of limb and joint. However, its unique role in bone homeostasis remained largely unknown. Here, we found that canonical Hh signaling pathway was gradually augmented during osteoclast differentiation. Genetic inactivation of Hh signaling in osteoclasts, using Ctsk-Cre;Smof/f conditional knockout mice, disrupted both osteoclast formation and subsequent osteoclast-osteoblast coupling. Concordantly, either Hh signaling inhibitors or Smo/Gli2 knockdown stunted in vitro osteoclast formation. Mechanistically, Hh signaling positively regulated osteoclast differentiation via transactivation of Traf6 and stabilization of TRAF6 protein. Then, we identified connective tissue growth factor (CTGF) as an Hh-regulatory bone formation-stimulating factor derived from osteoclasts, whose loss played a causative role in osteopenia seen in CKO mice. In line with this, recombinant CTGF exerted mitigating effects against ovariectomy induced bone loss, supporting a potential extension of local rCTGF treatment to osteoporotic diseases. Collectively, our findings firstly demonstrate that Hh signaling, which dictates osteoclast differentiation and osteoclast-osteoblast coupling by regulating TRAF6 and CTGF, is crucial for maintaining bone homeostasis, shedding mechanistic and therapeutic insights into the realm of osteoporosis.

Preparation and Closed-Loop Recycling of Ultra-High-Filled Wood Flour/Dynamic Polyurethane Composites.

The development of biomass-based composites has greatly reduced the daily consumption of plastics. However, these materials are rarely recyclable, thus, posing a severe threat to the environment. Herein, we designed and prepared novel composite materials with ultra-high biomass (i.e., wood flour) filling capacity and good closed-loop recycling properties. The dynamic polyurethane polymer was polymerized in situ on the surface of wood fiber, and then they were hot-pressed into composites. Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and dynamic thermomechanical analysis (DMA) measurements reveal good compatibility between the polyurethane and wood flour in the composites when the wood flour content is ≤80 wt%. The maximum tensile and bending strength of the composite are 37 and 33 MPa when the wood flour content is 80%. The higher wood flour content results in higher thermal expansion stability and creep resistance in the composites. Moreover, the thermal debonding of dynamic phenol-carbamate bonds facilitates the composites to undergo physical and chemical cycling. The recycled and remolded composites exhibit good mechanical property recovery rates and retain the chemical structures of the original composites.

SIRT5-related desuccinylation modification of AIFM1 protects against compression-induced intervertebral disc degeneration by regulating mitochondrial homeostasis.

Mitochondrial dysfunction plays a major role in the development of intervertebral disc degeneration (IDD). Sirtuin 5 (SIRT5) participates in the maintenance of mitochondrial homeostasis through its desuccinylase activity. However, it is still unclear whether succinylation or SIRT5 is involved in the impairment of mitochondria and development of IDD induced by excessive mechanical stress. Our 4D label-free quantitative proteomic results showed decreased expression of the desuccinylase SIRT5 in rat nucleus pulposus (NP) tissues under mechanical loading. Overexpression of Sirt5 effectively alleviated, whereas knockdown of Sirt5 aggravated, the apoptosis and dysfunction of NP cells under mechanical stress, consistent with the more severe IDD phenotype of Sirt5 KO mice than wild-type mice that underwent lumbar spine instability (LSI) surgery. Moreover, immunoprecipitation-coupled mass spectrometry (IP-MS) results suggested that AIFM1 was a downstream target of SIRT5, which was verified by a Co-IP assay. We further demonstrated that reduced SIRT5 expression resulted in the increased succinylation of AIFM1, which in turn abolished the interaction between AIFM1 and CHCHD4 and thus led to the reduced electron transfer chain (ETC) complex subunits in NP cells. Reduced ETC complex subunits resulted in mitochondrial dysfunction and the subsequent occurrence of IDD under mechanical stress. Finally, we validated the efficacy of treatments targeting disrupted mitochondrial protein importation by upregulating SIRT5 expression or methylene blue (MB) administration in the compression-induced rat IDD model. In conclusion, our study provides new insights into the occurrence and development of IDD and offers promising therapeutic approaches for IDD.

Satellite greenness and solar-induced chlorophyll fluorescence reveal reverse desertification in Gurbantunggut Desert.

The desertification reversal is a process of revegetation and natural restoration in fragile dryland areas due to human activities and climate change mediation. Understanding the impact of desertification reversion on terrestrial ecosystems, including vegetation greenness and photosynthetic capacity, is crucial for land policy-making and carbon-cycle model improvement. However, the phenomenon of desertification reversal is rarely mentioned in previous studies, which dramatically limits the understanding of vegetation dynamics in the arid area. Therefore, it is of great necessity to investigate the status of desertification reversal on the ecosystem in arid areas. In this study, we first reported the phenomenon of desertification reversion over the southern edge of the Gurbantunggut Desert through the Moderate-resolution Imaging Spectroradiometer classification map year by year. We discussed the consequences, ways, and causes of desertification reversion. Our results showed that the desertification reversal significantly increased vegetation greenness and photosynthetic capacity, which largely offset the negative impact of desertification on the ecosystem productivity; cropland expansion and grassland's natural restoration were the two main ways of desertification reversal; the improvement of soil-water condition was an essential environmental factor leading to the phenomenon of reverse desertification. This finding highlights the importance of desertification reversal in the carbon cycle of dryland ecosystems and prove that desertification reversal is an integral part of global and dryland vegetation greening.

XMU-MP-1 attenuates osteoarthritis via inhibiting cartilage degradation and chondrocyte apoptosis.

Osteoarthritis (OA) is the most prevalent type of degenerative joint disease; it is reported to be associated with inflammatory responses, chondrocyte apoptosis, and cartilage degeneration. XMU-MP-1 is a selective MST1/2 inhibitor which activates the downstream effector YAP and promotes cell growth. It has displayed excellent benefits in mouse intestinal repair, as well as liver repair and regeneration. However, the effects of XMU-MP-1 on OA remain unclear. In this study, we investigated the therapeutic role of XMU-MP-1 on interleukin-1ß (IL-1ß)-induced inflammation in mice chondrocytes and the destabilization of the medial meniscus surgery (DMM)-induced OA model. In chondrocytes, treatment with XMU-MP-1 elevated the matrix metalloproteinases (Mmp3, Mmp13) and decreased the extracellular matrix (Col2, Acan) induced by IL-1ß. Moreover, XMU-MP-1 strongly inhibited IL-1ß-induced chondrocyte apoptosis and significantly promoted chondrocyte proliferation. Furthermore, XMU-MP-1 demonstrated a protective and therapeutic influence on the mouse OA model. These findings indicate that XMU-MP-1 may have a protective effect on cartilage degradation and may be a new potential therapeutic option for OA.

Drugging the circadian clock feedback cycle to ameliorate cartilage degeneration.

Dampened peripheral clocks have been linked to osteoarthritis (OA), yet it is unclear whether drugging the clock can ameliorate OA. Given that RORs and REV-ERBs mediate respectively, positive and negative transcriptional feedback of the master clock gene BMAL1, we investigate whether RORs agonist Nobiletin (NOB) and SR1078, and REV-ERBs antagonist SR8278 can enhance BMAL1 expression and attenuate cartilage degeneration. NOB and SR8278 promoted BMAL1 expression and elicited mitigating effects against IL-1ß-induced degeneration of cartilage explants, as evidenced by increased cellular density and collagen synthesis along with alleviated catabolism and collagen denaturation. Despite promoted BMAL1 expression, SR1078 concomitantly suppressed chondrocyte anabolism and catabolism. Consistent with these findings, NOB and SR8278 treatment, but not SR1078, effectively attenuated structural destruction of articular cartilage in surgery-induced OA mouse models. Notably, the beneficial effects of NOB and SR8278 were evidently observed in IL-1ß-induced degeneration of human cartilage explants and immortalized human chondrocytes. Moreover, BMAL1 knockdown assays indicated that NOB and SR8278 enhanced clock function and concordantly rendered protection against altered anabolism and catabolism in a BMAL1-dependent regime. Collectively, our study suggests that targeting RORs and REV-ERBs to promote the dampened peripheral clocks could be a route taken to apply chronotherapy within the context of OA.

Consumption of common illicit drugs in twenty-one cities in southwest China through wastewater analysis.

Wastewater-based epidemiology (WBE) was applied to estimate illicit drugs consumption at a provincial scale in southwest China. A large-scale wastewater sampling campaign was carried out from October to November in 2021 in 156 different wastewater treatment plants (WWTPs). Two 24-h composite influent wastewater samples were collected in each WWTP. Concentrations of 11 illicit drugs or their metabolites were determined using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Benzoylecgonine, cocaine, 6-monoacetylmorphine, norketamine, 3,4-methylenedioxymethamphetamine (MDMA), and MDA were not detected in any of the wastewater samples. Methamphetamine and morphine were detected in >84% of samples, while ketamine was found in about 6% of the samples. The city-specific population-weighted consumption of methamphetamine and ketamine were in the range of 0.6-49.7 and N.D.-7.0 mg 1000 inh-1 day-1, respectively, with provincial population-weighted values of 22.6 and 2.4 mg 1000 inh-1 day-1 in southwest China. The city-specific load of morphine varied from 3.2 to 10.2 mg 1000 inh-1 day-1, with provincial population-weighted load of 6.7 mg 1000 inh-1 day-1. Taking into account therapeutic use of morphine and codeine, the provincial heroin consumption was estimated to be 10.3 mg 1000 inh-1 day-1, ranging from 1.7 to 18.5 mg 1000 inh-1 day-1 in 21 cities. Overall, the patterns of illicit drugs use were similar across southwest China, with high prevalence of methamphetamine and heroin, but relatively low use of ketamine. These findings could provide accurate drugs consumption information for timely identifying potential hotspots of illicit drugs use in southwest China.

Hedgehog signaling orchestrates cartilage-to-bone transition independently of Smoothened.

Although recent lineage studies strongly support a chondrocyte-to-osteoblast differentiation continuum, the biological significance and molecular basis remain undetermined. In silico analysis at a single-cell level indicates a transient shutdown of Hedgehog-related transcriptome during simulated cartilage-to-bone transition. Prompted by this, we genetically induce gain- and loss-of function to probe the role of Hedgehog signaling in cartilage-to-bone transition. Ablating Smo in hypertrophic chondrocytes (HCs) does not result in any phenotypic outcome, whereas deleting Ptch1 in HCs leads to disrupted formation of primary spongiosa and actively proliferating HCs-derived osteogenic cells that contribute to bony bulges seen in adult mutant mice. In HCs-derived osteoblasts, constitutive activation of Hedgehog signaling blocks their further differentiation to osteocytes. Moreover, ablation of both Smo and Ptch1 in HCs reverses neither persistent Hedgehog signaling nor bone overgrowths. These results establish a functional contribution of extended chondrocyte lineage to bone homeostasis and diseases, governed by an unanticipated mode of regulation for Hedgehog signaling independently of Smo.

Non-Isothermal Crystallization of Titanium-Dioxide-Incorporated Rice Straw Fiber/Poly(butylene succinate) Biocomposites.

In this work, titanium dioxide (TiO2)-incorporated rice straw fiber (RS)/poly(butylene succinate) (PBS) biocomposites were prepared by injection molding with different TiO2 powder loadings. The RS/PBS with 1 wt% TiO2 demonstrated the best mechanical properties, where the flexural strength and modulus increased by 30.34% and 28.39%, respectively, compared with RS/PBS. The non-isothermal crystallization of neat PBS, RS/PBS composites, and titanium-dioxide-incorporated RS/PBS composites was investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The non-isothermal crystallization data were analyzed using several theoretical models. The Avrami and Mo kinetic models described the non-isothermal crystallization behavior of neat PBS and the composites; however, the Ozawa model was inapplicable. The crystallization temperature (Tc), half-time of crystallization (t1/2), and kinetic parameters (FT) showed that the crystallizability followed the order: TiO2-incorporated RS/PBS composites > RS/PBS > PBS. The RS/PBS with 1 wt% TiO2 showed the best crystallization properties. The Friedman model was used to evaluate the effective activation energy of the non-isothermal crystallization of PBS and its composites. Rice straw fiber and TiO2 acted as nucleating agents for PBS. The XRD results showed that the addition of rice straw fiber and TiO2 did not substantially affect the crystal parameters of the PBS matrix. Overall, this study shows that RS and TiO2 can significantly improve the crystallization and mechanical properties of PBS composites.

Restoring the dampened expression of the core clock molecule BMAL1 protects against compression-induced intervertebral disc degeneration.

The circadian clock participates in maintaining homeostasis in peripheral tissues, including intervertebral discs (IVDs). Abnormal mechanical loading is a known risk factor for intervertebral disc degeneration (IDD). Based on the rhythmic daily loading pattern of rest and activity, we hypothesized that abnormal mechanical loading could dampen the IVD clock, contributing to IDD. Here, we investigated the effects of abnormal loading on the IVD clock and aimed to inhibit compression-induced IDD by targeting the core clock molecule brain and muscle Arnt-like protein-1 (BMAL1). In this study, we showed that BMAL1 KO mice exhibit radiographic features similar to those of human IDD and that BMAL1 expression was negatively correlated with IDD severity by systematic analysis based on 149 human IVD samples. The intrinsic circadian clock in the IVD was dampened by excessive loading, and BMAL1 overexpression by lentivirus attenuated compression-induced IDD. Inhibition of the RhoA/ROCK pathway by Y-27632 or melatonin attenuated the compression-induced decrease in BMAL1 expression. Finally, the two drugs partially restored BMAL1 expression and alleviated IDD in a diurnal compression model. Our results first show that excessive loading dampens the circadian clock of nucleus pulposus tissues via the RhoA/ROCK pathway, the inhibition of which potentially protects against compression-induced IDD by preserving BMAL1 expression. These findings underline the importance of the circadian clock for IVD homeostasis and provide a potentially effective therapeutic strategy for IDD.

Identification of decadal trends and associated causes for organic and elemental carbon in PM2.5 at Canadian urban sites.

Chemically resolved data for fine particulate matter (PM2.5) have been collected across Canada since 2003 through the National Air Pollution Surveillance (NAPS) network. Seven urban sites that have 10-17 years (2003-2019) of PM2.5 organic carbon (OC) and elemental carbon (EC) data were selected for analysis of decadal trends of OC, EC, and OC/EC ratio using the Ensemble Empirical Mode Decomposition method. Results showed that OC and EC decreased by 0.009-0.072 µg m-3 yr-1 and 0.028-0.049 µg m-3 yr-1, or 0.77-3.1 % yr-1 and 3.2-6.7 % yr-1, respectively, depending on the location. The more rapid decrease in EC than OC resulted in an increasing trend in the OC/EC ratio of 0.03-0.19 yr-1 across the sites. Macro-tracer approach was used to estimate source attributions of OC and EC from wood burning, fossil fuel combustion, and secondary aerosol formation. Using this approach, it was identified that the significant decrease in EC during the past decade was predominately caused by reduced on-road emissions. The decreased emissions from wood burning and transportation dominated the decline of OC, but such a decline was largely offset by the enhanced secondary organic aerosol (SOA) formation, resulting in much weaker decline of OC than EC. The enhanced SOA formation was due to the increased biogenic emissions fully offsetting the decreased anthropogenic emissions for volatile organic compounds. These findings highlight the need for quantifying biogenic sources of VOCs and other oxidants that are involved in OC formation at the national scale.

Spatiotemporal trends of PM2.5 and its major chemical components at urban sites in Canada.

To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM2.5 data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM2.5 collected at seven urban and two rural sites during 2010-2016 were analyzed to characterize geographical and seasonal patterns and associated potential causes. Site-specific seven-year mean gravimetric PM2.5 mass concentrations ranged from 5.7 to 9.6 µg/m3. Seven-year mean concentrations of SO42-, NO3-, NH4+, organic carbon (OC), and elemental carbon (EC) were in the range of 0.68 to 1.6, 0.21 to 1.5, 0.27 to 0.71, 1.1 to 1.9, and 0.37 to 0.71 µg /m3, accounting for 10.8%-18.1%, 3.7%-16.7%, 4.7%-7.4%, 18.4%-21.0%, and 6.4%-10.6%, respectively, of gravimetric PM2.5 mass. PM2.5 and its five major chemical components showed higher concentrations in southeastern Canada and lower values in Atlantic Canada, with the seven-year mean ratios between the two regions being on the order of 1.7 for PM2.5 and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO42- and NH4+ were comparable, while those of NO3-, OC, and EC were around 20%, 40%-50%, and 70%-80%, respectively, higher at urban than rural sites, indicating the regional scale impacts of SO42- and NH4+ and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO42- and wintertime peaks for NO3-, but those of NH4+, OC, and EC exhibited different seasonality at different locations.

Nitrogen wet deposition in the Three Gorges Reservoir area: Characteristics, fluxes, and contributions to the aquatic environment.

Measurements of nitrate nitrogen (NO3--N), ammonia nitrogen (NH4+-N), and dissolved organic nitrogen (DON) in precipitation were conducted at six different sites in the hinterland of the Three Gorges Reservoir (TGR) area from January 2016 to December 2017. The characteristics and the sources of nitrogen (N) species were identified. N flux of wet deposition in the hinterland of the TGR area were 13.56 ± 2.95 kg N ha-1 yr-1, of which the proportions of NO3--N, NH4+-N and DON were 60.9%, 25.1% and 14.0%, respectively. N flux in urban area was significantly higher than those in suburban, agricultural, and wetland areas. Industrial activities, biomass burning, and secondary transformation were the main contributors of N in urban area. In agricultural area, biomass burning, crustal, and manure were main sources of N. In suburban area, mixed emissions from industry, agriculture, and crustal sources were primary contributors of N. For wetlands, the major contributions were from industrial sector and biomass burning. Additional, analysis of regional distribution of dissolved N deposition in the TGR area was conducted by combining current study data and previously published data between 2000 and 2017. N flux of wet deposition in the entire TGR area ranged from 12.17 to 51.93 kg N ha-1 yr-1, with an average of 26.81 kg N ha-1 yr-1. Regional N distribution was greatest in the tail region, followed by the head region, and then the hinterland in the TGR area. The amount of N entering the TGR directly through atmospheric wet deposition was 2906 t yr-1, accounting for 2.1% of the total N inputs. N load from wet deposition had exceeded the critical loads from that of the water, forest, and even some farmland ecosystems in the TGR area. Decreasing NH3 emissions from agricultural activities is the key to alleviate the regional N deposition.

Impact of the COVID-19 pandemic and control measures on air quality and aerosol light absorption in Southwestern China.

China has been performing nationwide social lockdown by releasing the Level 1 response to major public health emergencies (RMPHE) to struggle against the COVID-19 (SARS-CoV-2) outbreak since late January 2020. During the Level 1 RMPHE, social production and public transport were maintained at minimal levels, and residents stayed in and worked from home. The universal impact of anthropogenic activities on air pollution can be evaluated by comparing it with air quality under such extreme conditions. We investigated the concentration of both gaseous and particulate pollutants and aerosol light absorption at different levels of (RMPHE) in an urban area of southwestern China. During the lockdown, PM2.5, PM10, SO2, NOx, and BC decreased by 30-50%, compared to the pre-Level 1 RMPHE period. Meanwhile, the decrease of NOx caused the rise of O3 by up to 2.3 times due to the volatile organic compounds (VOCs) limitation. The aerosol light absorption coefficient at multiple wavelengths decreased by 50%, and AAE decreased by 20% during the Level 1 RMPHE. BrC played essential roles in light absorption after the RMPHE was announced, accounting for 54.0% of the aerosol absorption coefficient at 370 nm. Moreover, the lockdown down-weighted the fraction of fossil fuel in BC concentrations to 0.43 (minima). This study characterizes air pollution at the most basic level and can provide policymakers with references for the "baseline."

Electrocatalytic N2-to-NH3 conversion using oxygen-doped graphene: experimental and theoretical studies.

Oxygen-doped graphene (O-G) derived from sodium gluconate is identified as a promising candidate to effectively catalyze ambient electrohydrogenation of N2 to NH3. Electrochemical tests on O-G in 0.1 M HCl suggest a large NH3 yield of 21.3 µg h-1 mgcat.-1 and a high faradaic efficiency of 12.6% at -0.55 and -0.45 V vs. reversible hydrogen electrode, respectively, with strong electrochemical and structural stability in 0.1 M HCl. Density functional theory calculations reveal the NRR catalytic mechanism and suggest that both the C[double bond, length as m-dash]O and O-C[double bond, length as m-dash]O groups contribute more greatly to the NRR compared with the C-O group.

Ambient electrochemical N2 reduction to NH3 under alkaline conditions enabled by a layered K2Ti4O9 nanobelt.

Using electrocatalytic N2 reduction to make NH3 is considered to be an attractive environmentally-friendly alternative to the Haber-Bosch process, which is rather energy-intensive and has heavy CO2 emissions. However, only limited success has been achieved in identifying metal oxides as effective electrocatalysts for the N2 reduction reaction (NRR) under alkaline conditions. In this communication, we report that a K2Ti4O9 nanobelt is able to effectively electrocatalyze the ambient NRR for N2-to-NH3 fixation at alkaline pH. When tested in 0.1 M KOH, a high NH3 yield of 22.88 µg h-1 mg-1cat. and a faradaic efficiency of 5.87% were attained. Moreover, K2Ti4O9 also demonstrates good selectivity and high electrochemical stability for NH3 formation.

Ni2P Nanosheets on Carbon Cloth: An Efficient Flexible Electrode for Sodium-Ion Batteries.

Transition-metal phosphides have been increasingly investigated because of their high theoretical specific capacity and low potential for sodium storage. Herein, we describe the development of Ni2P nanosheets on carbon cloth (Ni2P Ns/CC), which behaves as a flexible 3D anode for sodium-ion batteries. Such a Ni2P Ns/CC delivers a high capacity of 399 mA h g-1 at 0.2 A g-1. At 2 A g-1, it still delivers 72 mA h g-1 even after 1000 cycles. The impressive performance is attributed to such a self-supported structure. Moreover, a possible conversion reaction mechanism is also carefully revealed.