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Residential solid fuel combustion significantly impacts air quality and human health. Pelletized biomass fuels are promoted as a cleaner alternative, particularly for those who cannot afford the high costs of gas/electricity, but their emission characteristics and potential effects remain poorly understood. The present laboratory-based study evaluated pollution emissions from pelletized biomass burning, including CH4(methane), NMHC (nonmethane hydrocarbon compounds), CO, SO2, NOx, PM2.5(particulate matter with an aerodynamic diameter ≤2.5 μm), OC (organic carbon), EC (element carbon), PAHs (polycyclic aromatic hydrocarbons), EPFRs (environmentally persistent free radicals), and OP (oxidative potential) of PM2.5, and compared with those from raw biomass burning. For most targets, except for SO2and NOx, the mass-based emission factors for pelletized biomass were 62–96% lower than those for raw biomass. SO2and NOxlevels were negatively correlated with other air pollutants (p< 0.05). Based on real-world daily consumption data, this study estimated that households using pelletized biomass could achieve significant reductions (51–95%) in emissions of CH4, NMHC, CO, PM2.5, OC, EC, PAHs, and EPFRs compared to those using raw biomass, while the differences in emissions of NOxand SO2were statistically insignificant. The reduction rate of benzo(a)pyrene-equivalent emissions was only 16%, much lower than the reduction in the total PAH mass (78%). This is primarily attributed to the more PAHs with high toxic potentials, such as dibenz(a,h)anthracene, in the pelletized biomass emissions. Consequently, impacts on human health associated with PAHs might be overestimated if only the mass of total PAHs was counted. The OP of particles from the pellet burning was also significantly lower than that from raw biomass by 96%. The results suggested that pelletized biomass could be a transitional substitution option that can significantly improve air quality and mitigate human exposure.

In this paper, a newly stub-loaded twin-ring resonator (SLTRR) with symmetrical structure and multimode property is proposed and based on it, a sixth-order high-temperature superconducting (HTS) dual-band differential bandpass filter (BPF) with full controllable passbands is designed. The transmission line model (TLM) of the symmetrical SLTRR is constructed and its resonant characteristics are well analyzed with the help of odd/even-mode method. By proper loading six open-circuited stubs on the twin-ring, two individually adjustable DM frequencies can be obtained and utilized to constitute two DM passbands. Moreover, two open-circuited stubs installed at upper and lower portion of twin-ring are replaced by the shunted-lines, leading to the abundant design freedom for controlling two coupling coefficients of dual DM passbands separately. Furthermore, the required two external quality factors can be obtained independently by the proposed dual-band feeding structure. Thus, the center frequencies and bandwidths of two DM passbands can be fully controllable. Besides, a improved CM suppression within the second DM passband is realized by using frequency discrepancy technique. Finally, a dual-band differential BPF with center frequencies of 2.50/5.20 GHz is designed and fabricated on MgO with double deposited YBCO films. The measured results agree well with the simulated ones, and the filter has the advantages of high selectivity, low insertion loss, design flexibility and favorable CM suppression.

In this brief, a novel high-temperature superconducting (HTS) bandpass filter (BPF) with dual narrow passbands using dual-mode dual composite right/left-handed (D-CRLH) resonators is designed. The dual-mode resonator is cascaded by two single-mode D-CRLH resonators, where U-shaped microstrip line inductor is inverted to enclose interdigital capacitors, reducing the circuit size and decreasing the coupling between adjacent resonators. The characteristics of proposed resonator are obtained and analyzed by the equivalent circuit model. Finally, a four-pole dual-narrowband BPF operating at 890 / 1742.2 MHz with equal-ripple of 0.0432 dB is presented, fabricated, and measured, good agreement between the measured and simulated results can be achieved.

Cascaded H-bridge (CHB) converter has become an attractive topology for future large-scale photovoltaic (PV) plants in medium-voltage microgrids. However, the unequal irradiation and aging degree of PV arrays will lead to imbalanced and inconsistent output power between the three phases. This article presents a novel approach to integrating PV and energy storage (ES) systems inherent in microgrids, utilizing a hybrid CHB-based energy router (HCHB-ER), which is configured with a limited number of submodules to connect with the centralized ES. The proposed topology can handle serious interphase power imbalance and respond to grid-side power scheduling, without the appearance of overmodulation and common-mode voltage rise caused by traditional zero-sequence voltage injection methods. Under the three major constraints from the modulation level, the centralized energy storage maximum intrapower regulation boundary and submodule configuration ratio are analyzed in detail. Additionally, the power imbalance regulation capability of the proposed HCHB-ER across various configuration ratios is thoroughly evaluated and compared with the zero-sequence injection methods. Finally, the correctness and effectiveness of the proposed strategy are verified by simulations and experiments.

Household air pollution associated with solid fuel use is a long-standing public concern. The global population mainly using solid fuels for cooking remains large. Besides cooking, large amounts of coal and biomass fuels are burned for space heating during cold seasons in many regions. In this study, a wintertime multiple-region field campaign was carried out in north China to evaluate indoor PM2.5variations. With hourly resolved data from ∼1600 households, key influencing factors of indoor PM2.5were identified from a machine learning approach, and a random forest regression (RFR) model was further developed to quantitatively assess the impacts of household energy transition on indoor PM2.5. The indoor PM2.5concentration averaged at 120 μg/m3but ranged from 16 to ∼400 μg/m3. Indoor PM2.5was ∼60% lower in families using clean heating approaches compared to those burning traditional coal or biomass fuels. The RFR model had a good performance (R2= 0.85), and the interpretation was consistent with the field observation. A transition to clean coals or biomass pellets can reduce indoor PM2.5by 20%, and further switching to clean modern energies would reduce it an additional 30%, suggesting many significant benefits in promoting clean transitions in household heating activities.

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In this article, a compact high-temperature superconducting (HTS) fourth-order triband balanced bandpass filter (BPF) is developed by using a newly proposed multimode symmetric stub-loaded resonator (SSLR). The differential-mode and common-mode (CM) resonance characteristics of the SSLR are analyzed based on the transmission line theory and the even-/odd-mode method. Then, the configuration and coupling topology of a fourth-order triband balanced BPF are proposed, and variations in behaviors of the design parameters versus the structural dimensions of the filter are investigated. Finally, the triband balanced BPF operating at 1.56/4.22/5.8 GHz is designed and fabricated using HTS yttrium barium copper oxide (YBCO) films deposited on a MgO substrate. The measured filter response agrees well with the simulated one and shows excellent properties such as low insertion loss, high frequency selectivity, and larger CM suppression.

For the modular multilevel converter (MMC) based photovoltaic system, when the submodules (SMs) of MMC are connected to distributed photovoltaic (PV), power mismatches between legs and arms are the inherent problem. To eliminate the power mismatches, this article proposes a lightweight MMC-based grid-connected energy router (MGER) integrated PV and energy storage (ES). Large-scale PV and centralized ES are connected to horizontal three SMs through four-terminal dual-active-bridges (FDAB). The primary three full-bridges of which adopt synchronous switching to achieve mismatch power elimination between horizontal SMs, so legs power balance can be realized. In addition, the SMs three-phase symmetrical ripple-power can also cancel each other out under synchronous switching of primary FDAB, so as to achieve low capacitance and lightweight of MGER, and the MMC arms second-order circulating current can be also eliminated from root cause. In this article, the power mismatches analysis, MGER configuration, power mismatches elimination, control method, and lightweight implementation are discussed in detail. Finally, the correctness and effectiveness of the proposed scheme are verified by simulation and experiment.

In this brief, a novel capacitor-loaded stepped-impedance resonators (CL-SIRs) is proposed and adopted to construct dual-band balanced bandpass filter (BPF) with controllable passbands. The differential mode (DM) and common mode (CM) characteristics of the CL-SIRs are discussed in detail, and two DM resonant frequencies that can be independently controlled are selected to design the desired dual DM passbands. A novel dual-frequency feeding structure is proposed to not only independently control the external quality factors of the two DM passbands but also suppress the unwanted harmonics of DM bisection. Furthermore, a intrinsic high CM suppression is achieved by utilizing the magnetically coupled scheme. Also, multiple transmission zeros are generated because of the introduced source-loaded coupling, which highly improved the selectivity of two DM passbands. For verification, a dual-band balanced BPF operated at 2.5 GHz and 3.5 GHz is designed and fabricated. The measured results agree well with the simulated results, and the filter exhibits the attractive features of design flexibility, wide-stopband, high selectivity, and favorable CM suppression.

Future high-power-density engines require high level of intake boost. However, the effects of boosting on mixing, combustion and emissions in existing studies are inconsistent. In this paper, the mixing, combustion and emission characteristics with intake pressures of 100–400 kPa at low, medium and high loads are studied. The results show that the increase of intake pressures is conducive to the enhancement of air entrainment, while the air utilization ratios are reduced, thus requiring injection pressure to be optimized to effectively improve the mixing. For the intake pressures of 100 kPa, the average chemical reaction path is low-temperature reaction route, while the path of higher intake pressures is dominated by high-temperature pyrolysis. For soot emissions, when the equivalence ratio is lower than 0.175, the oxygen in the cylinder is sufficient, so the effect of temperature decrease is more significant, which leads to the increase of soot emissions with the increase of intake pressures. Otherwise, the effect of increasing oxygen concentration is more significant, so soot decreases accordingly. When the peak of global temperature is lower than 1800 K, the effect of the increase of oxygen concentration is more dominant, so the NOxemission increases with the increase of intake pressures. Otherwise, the rule of NOxemissions is consistent with temperature changes.

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Inherited anemia continues to pose a significant public health concern on a global scale, owing to its extensive geographical prevalence, substantial patient population, and profound ramifications. Here, we investigated detailed information on inherited anemias (including thalassemias, thalassemias trait, sickle cell disease, sickle cell trait, G6PD deficiency, and G6PD trait) for the period 1990–2019 from the Global Burden of Disease study. Over the course of three decades, there has been a persistent rise in the incidence of inherited anemias worldwide, culminating in a total of 44,896,026 incident cases in 2019. However, the prevalence of inherited anemias has exhibited a consistent downward trend over successive years. Significantly, these inherited anemias primarily impact females, exhibiting a male-to-female ratio of 1:1.88. Among males, the most prevalent inherited anemia is G6PD deficiency, whereas G6PD trait prevails among females. The incidence rates of inherited anemias and their temporal trend exhibited significant variations across different regions, with Central Sub-Saharan Africa displaying the highest incidence rates and Central Latin America experiencing the most substantial decline. The findings of this study suggest a significant correlation between the Socio-Demographic index (SDI) and incidence rates of inherited anemias, particularly in regions with lower SDI levels such as Africa and South Asia. These results contribute valuable insights for the analysis of global trends in the burden of inherited anemias.

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New membrane materials with excellent water permeability and high ion rejection are needed. Metal–organic frameworks (MOFs) are promising candidates by virtue of their diversity in chemistry and topology. In this work, continuous aluminum MOF-303 membranes were prepared on α-Al2O3substrates viaan in situhydrothermal synthesis method. The membranes exhibit satisfying rejection of divalent ions (e.g., 93.5% for MgCl2and 96.0% for Na2SO4) on the basis of a size-sieving and electrostatic-repulsion mechanism and unprecedented permeability (3.0 L·m–2·h–1·bar–1·μm). The water permeability outperforms typical zirconium MOF, zeolite, and commercial polymeric reverse osmosis and nanofiltration membranes. Additionally, the membrane material exhibits good stability and low production costs. These merits recommend MOF-303 as a next-generation membrane material for water softening.

In integral imaging, reproducing the depth information of three-dimensional (3D) objects accurately is one of the goals of scientific researchers. Based on the existing research, this paper proposes a new, to the best of our knowledge, elemental image array (EIA) generation algorithm, which does not need to know the depth information of the spatial scene. By dividing the distance between the display lens array (LA) and the synthetic LA equally, and comparing the variance of the pixels corresponding to the partial of the display LA at different positions, it can obtain the depth information of the 3D objects accurately, and then the value of the synthetic pixel can be calculated. Thus, a new EIA with accurate depth information is generated. Finally, the proposed algorithm has been verified in experiments of both virtual objects and real objects.

Black carbon (BC) emissions, derived primarily from incomplete fuel combustion, significantly affect the global and regional climate. Mass absorption efficiency (MAE) is one important parameter in evaluating the climate impacts of BC. Here, values and variabilities in the MAE of BC (MAEBC) from real-world residential emissions were investigated from a field campaign covering 163 burning events for different fuel–stove combinations. MAEBC(average: 12 ± 5 m2/g) was normally distributed and varied greatly by 2 orders of magnitude. Statistically significant differences in MAEBCwere found for various fuels, while no significant differences were observed among different stoves. The fuel difference explained 72 ± 7% of the MAEBCvariation. MAEBCdid not correlate with the modified combustion efficiency but positively correlated with the ratio of organic carbon (OC) to elemental carbon (EC) and negatively correlated with char-EC. The OC/EC ratio was not always lower in coal emissions in comparison to biomass burning emissions. Coal- and biomass-burning emissions had different profiles of carbon fractions. Char-EC, OC, OC/EC, and char-EC/soot-EC can explain 68.7% of the MAEBCvariation, providing the potential for predicting MAEBCfrom the carbon fractions, since they are more commonly measured and available.

Contaminant-bearing fine biochar particles (FBPs) may exert significantly different toxicity profiles from their contaminant-free counterparts. While the role of FBPs in promoting contaminant uptake has been recognized, it is unclear whether the binding of contaminants can modify the biochemical reactivity and toxicological profiles of FBPs. Here, we show that binding of benzo[a]pyrene (B(a)P, a model polycyclic aromatic hydrocarbon) at environmentally relevant exposure concentrations markedly alters the cytotoxicity of FBPs to macrophages, an important line of innate immune defense against airborne particulate matters (PMs). Specifically, B(a)P-bearing FBPs elicit more severe disruption of the phospholipid membrane, endocytosis, oxidative stress, autophagy, and compromised innate immune defense, as evidenced by blunted proinflammatory effects, compared with B(a)P-free FBPs. Notably, the altered cytotoxicity cannot be attributed to the dissolution of B(a)P from the B(a)P-bearing FBPs, but appears to be related to B(a)P adsorption-induced changes of FBPs bioreactivity toward macrophages. Our findings highlight the significance of environmental chemical transformation in altering the bioreactivity and toxicity of PMs and call for further studies on other types of carbonaceous nanoparticles and additional exposure scenarios.

The detailed combustion kinetic processes of a high-pressure direct injection (HPDI) natural gas (NG) marine engine was investigated in the present work. A postprocessing code was employed to visualize the characteristic reactions that determine the combustion process. To evaluate the effect of mixture stratification on the combustion process, various NG injection timings were employed and four representative combustion periods were selected, including the timings when 1% (CA1), 5% (CA5), 10% (CA10), and 50% (CA50) of the total fuel energy are released. A higher heat release rate (HRR) was generated with a more advanced NG start of injection (SOI) timing, which, however, had limited effects on the main representative exothermic reactions (REXRs) within the high heat release (HHR) region and the dominant formation reactions of CH2O and OH, which are known as the indicators of low heat release (LHR) and HHR, respectively. Besides, for different NG SOI timing simulation, the consumption of CH4was all dominated by reactions H + CH4= CH3+ H2and OH + CH4= CH3+ H2O and the dominated REXR of the LHR region was reaction CH3+ O2= CH3O2. Furthermore, with an advanced NG injection timing, significant changes were observed for the reaction paths of CH2, CH2O, and HCO from the premixed-combustion phase (CA10) to the mixing-controlled combustion phase (CA50). The results of the present study are able to provide a theoretical fundamental for the practical control of the HPDI NG marine engine.

A ducted fuel injection (DFI) strategy has been proposed as an efficient approach to reduce the soot emission in direct-injection compression ignition engines. By injecting the fuel through a small tube within the combustion chamber, a leaner air–fuel mixture is generated compared to the conventional free spray approach, which significantly inhibits the soot formation and helps to reduce the dependence of the engine on after-treatment systems. However, the soot reduction mechanism is still not fully understood. Therefore, in this work, a three-dimensional computational investigation was performed to explain the experimental results. Four different reduced chemical mechanisms were used to simulate the reacting spray A (n-dodecane) data from both the Engine Combustion Network group and literature. An improved post-processing method was also proposed to investigate the detailed combustion feature. The results revealed that the ignition processes using different mechanisms were all dominated by the same reaction CH2O + OH = HCO + H2O. Of the four reduced mechanisms, Yao mech demonstrated the best-predicted performance. Compared to the free-spray case, the DFI case generated a longer ignition delay and lift-off length and lower soot concentration owing to the significant reduction of air entrainment and longer core jet velocity from the duct exit to the lift-off length location. In addition, the DFI case had a significantly longer low-temperature heat release region but a shorter high-temperature heat release region and a smaller core between these two regions, which helps to reduce the sooting tendency.

High-pressure direct-injection (HPDI) natural gas engines continue to draw much attention for the highly efficient and clean combustion process compared to traditional diesel engines. However, the real ignition processes of HPDI natural gas engines are very different from the ignition processes of n-heptane/methane/air mixtures. In this work, the ignition of homogeneous n-heptane/methane mixtures in a constant-volume chamber under HPDI natural gas enginelike conditions is numerically studied. Results show that the temperature and equivalence ratio have a significant effect on ignition delays over a wide range of conditions, whereas the effects of the pressure and the methane mass fraction are only profound at low temperatures. A small number of intermediate species almost does not influence the effects of various factors (temperature, equivalence ratio, pressure, and methane mass fraction) on the ignition of the fuel blends. With more intermediate species, the effects of equivalence ratio on the ignition of the fuel blends are further mitigated. Based on the calculated results, ignition delay regions were categorized into four major regions by the equivalence ratio and methane mass fraction in fuel/air mixtures. A small number of intermediate species almost does not affect the four regions. However, with more intermediate species, the four regions are very different from those of fuel/air mixtures. The sensitivity analysis indicates that intermediate species can significantly reduce the effects of n-heptane-related reactions. Rates of production (ROP) analyses show that a small number of intermediate species almost has no effect on ROPs, whereas more intermediate species mainly affect not only the ROPs but also the temperature. Reaction path analysis shows that the intermediate species have a significant influence on the reaction paths of both n-heptane and methane. This work can provide a theoretical basis for further investigation of the ignition control of HPDI dual-fuel engines.

ABSTRACTThis research evaluated the ability of different coupled climate models to simulate the historical variability of potential evapotranspiration (PET) for the time period 1979–2017 in phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6, respectively). Their projected future changes of PET under two emission scenarios for the 21st century were also compared. Results show that PET has an increasing trend of 0.2–0.6 mm d−1/50 yr over most land surfaces and that there are clear regional differences. The future value of PET is higher in the CMIP6 multi-model simulations than in the CMIP5 ones under the same emissions scenario, possibly because CMIP6 models simulate stronger warming for a given forcing or scenario. The contributions of each individual climate driver to future changes in PET were examined and revealed that the surface vapor pressure deficit makes a major contribution to changes in PET. Shortwave radiation increases PET in most terrestrial regions, except for northern Africa, East Asia, South Asia, and Australia; the effect of longwave radiation is the opposite to that of shortwave radiation. The contribution of surface wind speed to PET is small, but results in a slight reduction.

A potential risk from human uptake of microplastics is the release of plastics-associated xenobiotics, but the key physicochemical properties of microplastics controlling this process are elusive. Here, we show that the gastrointestinal bioaccessibility, assessed using an in vitro digestive model, of two model xenobiotics (pyrene, at 391–624 mg/kg, and 4-nonylphenol, at 3054–8117 mg/kg) bound to 18 microplastics (including pristine polystyrene, polyvinyl chloride, polyethylene terephthalate, polypropylene, thermoplastic polyurethane, and polyethylene, and two artificially aged samples of each polymer) covered wide ranges: 16.1–77.4% and 26.4–83.8%, respectively. Sorption/desorption experiments conducted in simulated gastric fluid indicated that structural rigidity of polymers was an important factor controlling bioaccessibility of the nonpolar, nonionic pyrene, likely by inducing physical entrapment of pyrene in porous domains, whereas polarity of microplastics controlled bioaccessibility of 4-nonylphenol, by regulating polar interactions. The changes of bioaccessibility induced by microplastics aging corroborated the important roles of polymeric structures and surface polarity in dictating sorption affinity and degree of desorption hysteresis, and consequently, gastrointestinal bioaccessibility. Variance-based global sensitivity analysis using a deep learning neural network approach further revealed that micropore volume was the most important microplastics property controlling bioaccessibility of pyrene, whereas the O/C ratio played a key role in dictating the bioaccessibility of 4-nonylphenol in the gastric tract.

In the present study, triplicate rings of 360° pipe surfaces of an operational drinking water distribution pipe were swabbed. Each ring was equally divided into 16 parts for swabbing. The collected swabs were grouped into 3 sections and compared with the biofilm samples sampled by sonication of specimens from the same pipe. The results showed that the biofilm is unevenly distributed over the 16 parts and the 3 sections of the pipe surface. Both the active biomass and the number of observed OTUs increased as the measurements proceeded from the top to the bottom of the pipe. The bacterial community was dominated in all sections by Proteobacteria. At the genus level, Nitrospiraspp., Terrimonasspp., and Hyphomicrobiumspp. were dominant in all sections. Gaiellaspp. and Vicinamibacterspp. dominated in S-I, Blastopirellulaspp. and Pirellulaspp. dominated in S-II, while Holophagaspp. and Phaeodactylibacterspp. dominated in S-III. When swabbing and pipe specimen sonication were compared, the results showed that the sampling strategy significantly influences the obtained biofilm bacterial community. A consistent multisectional swabbing strategy is proposed for future biofilm sampling; it involves collecting swabs from all sections and comparing the swabs from the same position/section across locations.

Carbonaceous nanomaterials, such as graphene oxide (GO), are susceptible to environmental reduction that affects their fate and impact in aquatic environments. Here, we demonstrate that sulfide and ferrous iron, the most prevalent natural reductants, significantly alter the surface properties of GO, which can enhance the accumulation of both organic and inorganic contaminants on GO. Strikingly, these two reductants target different surface O-functional groups while diminishing the overall surface O-functionality of GO (i.e., C/O ratio) to a similar extent at a given reductant concentration. Hence, the two reductants have distinctly different effects on the adsorption of organics vs.heavy metals onto GO. At the same reductant concentration, iron and sulfide reduction increases the adsorption of naphthalene, 1,2,4,5-tetrachlorobenzene and 2,4-dichlorophenol comparably, as the adsorption of polar and nonpolar organic contaminants on GO is driven primarily by hydrophobic effects and π–π interactions, which correlate reasonably with the C/O ratio of GO. Interestingly, while iron reduction significantly promotes the adsorption of heavy metals, sulfide reduction has essentially no effect. Iron reduction apparently increases the abundance of GO carboxyl groups and consequently promotes the binding of mercury and lead viainner-sphere complexation. The increasing content of carbonyl groups induced by sulfide reduction may enhance metal adsorption on GO, but this effect is probably offset by the simultaneous decrease of carboxyl groups and decreasing negative charges of GO. This research highlights the importance of understanding the specific reduction pathway of carbonaceous nanomaterials when assessing their impact on the environmental behavior of metals.

Rising environmental concerns associated with the domestic use of solid biofuels have driven the search for clean energy alternatives. This study investigated the in vitrotoxicological characteristics of PM2.5emissions from residential biomass pellet burning using the A549 epithelial cell line. The potential of modern pellet applications to reduce PM2.5emissions was evaluated by considering both mass reduction and toxicity modification. PM2.5emissions from raw and pelletized biomass combustion reduced cell viability, indicative of acute toxicity, and also protein expression associated with epithelial barrier integrity, implying further systemic toxicity, potentially via an oxidative stress mechanism. Toxicity varied between PM2.5emissions from raw biomass and pellets, with pelletized straw and wood inducing cytotoxicity by factors of 0.54 and 1.30, and causing epithelial barrier damage by factors of 1.76 and 2.08, respectively, compared to their raw counterparts. Factoring in both mass reduction and toxicity modifications, PM2.5emissions from pelletized straw and wood dropped to 1.83 and 5.07 g/kg, respectively, from 30.1 to 9.32 g/kg for raw biomass combustion. This study underscores the effectiveness of pelletized biomass, particularly straw pellets, as a sustainable alternative to traditional biofuels and highlights the necessity of considering changes in toxicity when assessing the potential of clean fuels to mitigate emissions of the PM2.5complex.

Dust emissions can lead to a series of environmental hazards and are thus a global concern. However, due to the difficulties of dust source identification, there are still great uncertainties in the calculation of dust yield on a global scale. The Qinghai-Tibetan Plateau presents some challenges for understanding the region’s calculation of the global dust budget. To address these issues, the Hoh Xil Plateau, a typical dust source on the Qinghai-Tibetan Plateau, was selected as the study area for analyzing dust emission processes and associated influencing factors via a robust model. The results showed that dust emissions on the Hoh Xil Plateau occurred mainly in spring and winter. The wide distribution of bare land and sandy land on the Hoh Xil Plateau is the main reason for the high dust emissions. Wind speed is the dominant factor influencing annual dust emission, while precipitation and temperature were negatively correlated with the dust emission. The recession of expansive lakes in the region resulted in an increase in sandy lake-shores, which induced a potential increase in dust emissions. In addition, the effects of human activities on dust emissions were evident. Positive and negative effects on dust emission changes coexisted on the Hoh Xil Plateau and depended on the development of the county-level economy and the implementation of ecological engineering measures. We believe that this study will clarify the dust yield of the Qinghai-Tibetan Plateau and provide valuable information for understanding the driving factors that cause variations in aeolian processes on the Qinghai-Tibetan Plateau.

The soot formation in the combustion of four oxygenated fuels on a single-cylinder engine has been investigated experimentally and numerically. To accomplish this objective, a reduced combustion mechanism was proposed for the modeling studies, which has been extensively validated. Then direct injection compression ignition experiments fueled with diesel, biodiesel, and its blends with 20% volume fraction of ethanol (E20), n-butanol (B20), and 2,5-dimethylfuran (D20) have been conducted. In the three-dimensional (3-D) modeling studies, the reduced mechanism can well predict the experimental combustion and soot emission results. In contrast to the combustion phasing, the soot emissions for the five fuels were sequenced as diesel > biodiesel > B20 > D20 > E20, which was mainly due to the different oxygen content and fuel reactivity in the spray-combustion processes. Furthermore, 0-D modeling investigations were conducted as well to clarify the effects of the different oxygenated structures on the polycyclic aromatic hydrocarbons (PAHs) formation under homogeneous condition. It was shown that, for the five pure fuel cases, the sooting tendencies were sequenced as ethanol < n-butanol < methyl-decanoate < n-heptane < 2,5-dimethylfuran. According to the reaction pathway analyses, oxygenated fuels with a longer carbon chain molecular structure could produce more intermediate species, which favor the PAHs and soot formation. However, much more phenol and cyclopentadienyl radical can be produced due to the special cyclic structure of 2,5-dimethylfuran, resulting in the highest soot formation among these investigated fuels.

For heavy-duty truck, multi-mode power split hybrid transmission scheme (MPSHTS) has good adaptability. However, the moment of inertia at both ends of the clutch is large. If there is a large speed difference in the clutch engagement process, it will increase clutch wear, engine stall and other problems. This paper proposed a new design method of multi-mode power split hybrid powertrain, which was different from the proof by exhaustion aiming at mode switching without speed difference. It included: the conditions for achieving mode connection without speed difference was obtained based on the lever method for dynamic characteristic analysis. Evaluation index for power split mechanisms that comprehensively considered power source and transmission system was established. Combining the mode connection conditions and the optimized basic configuration, the characteristic of no speed difference could be ensured by adjusting the power coupling mechanism. A multi-mode scheme based on optimized configuration and work mode requirements could be obtained. Finally, parameter matching and simulation verification on the designed scheme was carried out. It suggested that the designed system improved fuel economy by 4.14% compared with the original scheme.

Lead-free pnictogen/noble metal halide double perovskites Cs2BiAgCl6, Cs2BiAgBr6, and Cs2SbAgCl6are some of the most promising environmentally friendly alternatives to lead–halide perovskites. However, due to their relatively large band gaps (1.9–2.2 eV), they are not yet competitive candidates for use in photovoltaic devices. In this work, we perform a systematic study of the thermodynamic stability of the entire family of Cs2BB′X6compounds (B = Bi and Sb, B′ = Cu, Ag, and Au, and X = Cl, Br, and I), and we explore the possibility of chemical mixing as a route to stabilize pnictogen/noble metal halide perovskites with low band gaps. Our calculations indicate that Cs2BiAg1–xCuxCl6mixes should be amenable to synthesis and could reduce the band gap down to 1.6–1.9 eV.

This paper numerically investigated the chemical kinetic process of a reacting n-dodecane spray flame under a compression ignition combustion condition. To achieve this target, a data processing method by coupling with the chemical kinetic mechanism was proposed and verified. The modeling results demonstrated that before ignition, the spray-flame structure was primarily composed of three regions: (1) an exothermic low-temperature heat release (LTHR) region in the upstream spray core, (2) an endothermic region surrounding the LTHR region, and (3) an exothermic high-temperature heat release (HTHR) region in the downstream spray. Based on the analyses of representative reactions and reaction pathways, the reaction R48 (C6H13+ O2= C6H13O2) was found to be the representative exothermic and endothermic reaction for both the LTHR and endothermic regions, while the reaction R276 (HCO + O2= CO + HO2) dominated the heat release in the HTHR region, which laid the foundation for the ignition. After the peak premixed heat release, hydrocarbons could not be fully oxidized due to O2deficiency and intruded into the high-temperature combustion region instead, leading to the diffusion combustion and initial soot formation. However, the upstream spray-flame structure was slightly affected by the further development of combustion, owing to the comparatively stable and lower temperature. The proposed code can provide more insights into the details of engine combustion and emission formation processes.

Increasing helium use in research and production processes necessitates separation techniques to secure sufficient supply of this noble gas. Energy-efficient helium production from natural gas is still a big challenge. Membrane gas separation technology could play an important role. Herein, a novel poly(p-phenylene benzobisimidazole) (PBDI) polymeric membrane for helium extraction from natural gas with low He abundance is reported. The membranes were fabricated by a facile interfacial polymerization at room temperature. The thin and defect-free membrane structure was manipulated by the confined polymerization of monomers diffusing through the interface between two immiscible liquids. Both He/CH4selectivity and He permeance are competitive over those of other commercial perfluoropolymers. Even at low He content of 1%, separation performance of the PBDI membrane transcended the current upper bound. The unprecedented selectivity (>1000) together with the excellent stability (∼360 h) endows PBDI membranes with a great potential for energy-efficient industrial recovery and production of this precious He resources from reservoirs with low abundance.

Plastic debris, in particular, microplastics and nanoplastics, is becoming an emerging class of pollutants of global concern. Aging can significantly affect the physicochemical properties of plastics, and therefore, may influence the fate, transport, and effects of these materials. Here, we show that aging by UV or O3exposure drastically enhanced the mobility and contaminant-mobilizing ability of spherical polystyrene nanoplastics (PSNPs, 487.3 ± 18.3 nm in diameter) in saturated loamy sand. Extended Derjaguin–Landau–Verwey–Overbeek calculations and pH-dependent transport experiments demonstrated that the greater mobility of the aged PSNPs was mainly the result of surface oxidation of the nanoplastics, which increased not only the surface charge negativity, but more importantly, hydrophilicity of the materials. The increased mobility of the aged PSNPs significantly contributed to their elevated contaminant-mobilizing abilities. Moreover, aging of PSNPs enhanced the binding of both nonpolar and polar contaminants, further increasing the contaminant-mobilizing ability of PSNPs. Interestingly, aging enhanced binding of nonpolar versus polar compounds via distinctly different mechanisms: increased binding of nonpolar contaminants (tested using pyrene) was mainly the result of the modification of the polymeric structure of PSNPs that exacerbated slow desorption kinetics; for polar compounds (4-nonylphenol), aging induced changes in surface properties also resulted in irreversible adsorption of contaminants through polar interactions, such as hydrogen bonding. The findings further underline the significant effects of aging on environmental fate and implications of nanoplastics.