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Coal combustion is the primary source of air pollution in China, especially the heavy metals (HMs) concentrated in the submicron particles. This paper discusses the enhancement of HMs absorption efficiencies during coal combustion experiments. By adding the modified Ca-based sorbents, the orthogonal design was used in this experiment. Combining with the analysis of variance and capturing rate of HMs, the optimal combination was arrived at. BP neural network model was established and trained using orthogonal capturing tests data to reach the best compositions. Confirmatory trial was conducted, thus the BP neural network model can be used to solve complex nonlinear optimization problems. [ABSTRACT FROM AUTHOR]

• The α-diversity of rare bacteria was greater in the depositional zones than in the eroding slopes. • The α-diversity of abundant bacteria between the eroding slopes and depositional zones showed no difference. • The community compositions of abundant and rare bacteria differed between the eroding slopes and depositional zones. • Abundant and rare species jointly maintained the stability of co-occurrence network in eroded ecosystem. • The α-diversity of rare bacteria showed closer linkage with SCCF than abundant bacteria. Elucidating the interaction between microorganisms and soil carbon cycling functionality (SCCF) in the eroded ecosystems, can improve our understanding of the mechanisms by which soil erosion and deposition affect soil organic carbon pool. Abundant and rare sub-communities are the integral components in driving SCCF. However, changes in abundant and rare sub-communities, as well as their contributions to SCCF, remain unclear in the eroded ecosystems. In this study, changes in abundant and rare sub-communities and their correlations with SCCF were comparatively explored with respect to soil erosion and deposition in the Loess Plateau. The α-diversity of rare sub-communities in the depositional zones was 4% higher than that in the eroding slopes, but there was no significant difference in α-diversity of abundant sub-communities between the eroding slopes and depositional zones. The compositions of abundant and rare sub-communities differed between the eroding slopes and depositional zones. Regarding the co-occurrence network of the eroded ecosystems, abundant sub-communities compared with rare sub-communities presented a higher degree and betweenness centrality; however, rare sub-communities possessed more frequent interactions with other species than abundant sub-communities, especially positive interactions. The α-diversity of abundant and rare sub-communities in ecological clusters showed positive links with SCCF. The link between α-diversity of abundant sub-communities and SCCF was weaker than that with rare sub-communities, which was related to the significant disparity in the abundance of functional genes involved in SCCF and the extent of functional redundancy between abundant and rare sub-communities in the eroded ecosystems. The functional difference of abundant and rare sub-communities in improving SCCF under soil erosion and deposition, is important for accurately assessing the effects of microbial communities on soil organic carbon pool in regions predominated with fragmented eroded landscapes. [ABSTRACT FROM AUTHOR]

In this article, the effect of a chamber's geometrical parameters on suppressing gas explosion propagation was studied. Three rectangular chambers were used in the study, with a constant length of 0.5 m, a constant height of 0.2 m, and a variable width of 0.3 m, 0.5 m, and 0.8 m; each chamber was installed in a pipeline system for experimental research. The experimental results showed that when the chamber length and height were fixed at 0.5 m and 0.2 m, respectively, the suppression effect of the chamber on the explosion shockwave improves with the increase in the chamber width; when the chamber width increases to 0.8 m, the chamber has suppressive effect on explosion shockwave propagation. It was also found that the suppression effect of the chambers on the explosion flame improves with the increase in the chamber width; when the width of the chamber is 0.5 m, the chamber effectively suppresses explosion flames. Based on the experimental results, a numerical model was established to simulate the suppression effect of five types of chambers with a length, width, and height of 0.5 m × 0.3 m × 0.2 m, 0.3 m × 0.5 m × 0.2 m, 0.5 m × 0.5 m × 0.2 m, 0.5 m × 0.8 m × 0.2 m, and 0.8 m × 0.5 m × 0.2 m, respectively. The numerical simulation results indicated that when the chamber length and height are constant at 0.5 m and 0.2 m, respectively, the suppressive effect of the chamber on the shockwave improves as the chamber width increases; when the chamber width increases to 0.8 m, the shockwave overpressure at the chamber outlet is attenuated by 10.61%, indicating that the chamber suppresses the propagation of explosion shockwave, which is consistent with the experimental results obtained in the study. It was also found that when the chamber width and height were constant at 0.5 m and 0.2 m, respectively, as the chamber length increases, the overpressure increases first and then weakens. When the chamber length increases to 0.8 m, the overpressure at the chamber outlet is attenuated by −14.16%, indicating that the chamber is not able to suppress the propagation of explosion shockwave. Finally, a numerical simulation of the propagation process of a methane-air mixture and explosion flames in different chambers was performed to analyse the effect of chamber geometrical parameters on explosion suppression effect. [ABSTRACT FROM AUTHOR]

Summary: Currently, the prevention and control of coal spontaneous combustion (CSC) mainly depend on liquid or inert gas injection. In this study, the mixed sol solution was prepared with methylcellulose (MC), polyethylene glycol (PEG), and surfactant sodium dodecyl sulfate (SDS). It has the advantages of in‐situ, nontoxicity, easy biodegradation, etc., and can retain a large amount of water by sol‐gel transition. The effect of each component on the gel properties was analyzed by using central composite design (CCD) of response surface methodology (RSM). The optimal values of independent variables were 1.99 wt% MC, 6 wt% PEG, and 8 mM/L SDS, under which the response values were obtained as gelation temperature 70°C, gelation time 75 seconds, gel strength 20.32 kPa, and seepage rate 28.51%. The obtained thermosensitive hydrogel (TSH) was characterized by Fourier transform infrared spectroscopy (FT‐IR) and differential scanning calorimetry (DSC). The results showed that the hydrogel was formed by physical cross‐linking of MC‐PEG‐SDS ternary system. The gelation temperature of MC increased in the coexistence of SDS and PEG. The temperature‐programmed experiment of coal samples treated with inhibitors showed that the CO inhibition rate of 8 wt% MC‐PEG‐SDS was higher than that of 20 wt% MgCl2 at 90‐120°C. Besides, TSH and l‐ascorbic acid (VC) were mixed to form a composite inhibitor (8 wt% MC‐PEG‐SDS/4 wt% VC) based on physical cooling and chemical inhibition. The experiment results showed that the composite inhibitor had a significant inhibitory effect on coal oxidation, and the corresponding CO inhibition rate (RTi) values fluctuated in the range of 47.68% to 83.57%. Therefore, TSH can act as a carrier of antioxidants and their combination can be used to prevent CSC. [ABSTRACT FROM AUTHOR]

Understanding the structure of coal is crucial to explain its chemical reactivity. In order to study the microstructure characteristics of coal in-depth, ultimate analysis, solid-state 13C nuclear magnetic resonance (13C-NMR), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) are used to analyze the Datong coal. The results show that the aromaticity of Datong coal is 62.60%, and the ratio of aromatic bridge carbon to aromatic peripheral carbon is 0.238, indicating that more naphthalene and anthracene are in the aromatic structure of coal. Hydroxyl (C–O), carbonyl (C=O) and carboxyl (COO–) are the main oxygen-containing groups in coal, and the nitrogen element mainly exists in the form of pyrrole and pyridine. The main substitution modes on the benzene ring are di- and tri-substituted. Based on the above analysis, the 2D and 3D macromolecular models are constructed and optimized by using computer-aided modeling. The model is verified by 13C-NMR and FTIR spectra with density functional theory calculations. The coal molecular formula is defined as C 149 H 112 O 24 N 2. The reaction sites in coal structure are oxygen-containing functional groups and aliphatic structures (–CH, –CH 2). Therefore, the molecular structure of Datong coal has been systematically described and understood at the molecular level based on experimental data and quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Coal plays an important role in the Chinese energy source. The heavy metals released from combustion process stay in the environment and are not easily degraded. This paper examines 8 coal samples from China. It explores the content, characteristics, transformation and control of heavy metals through the microwave digestion, sequential chemical extraction, static burning test and X-ray diffraction (XRD) methods. The zinc (Zn) and cadmium (Cd) in coal mainly exist in exchangeable, sulfide, and residual forms. The arsenic (As) content is mainly present in the sulfide binding state. For these three elements, degrees of organic speciation are not considered to be important and the residue speciation mainly occurs in coal ash. After coal combustion, the heavy metals in coal ash are relatively enriched, and the harm to the environment cannot be ignored. Most of the Cd, As and Zn residues are released into the atmosphere and their volatility rates can be ordered as follows: As > Zn > Cd. There are significant differences in mineral composition between the main phases and mineral carriers of heavy metals in coal and ash. Based on these differences, modified calcium carbonate (CaCO 3 ) is used as an additive. In orthogonal experiment, the optimal parameters for treating heavy metals are the temperature (1000 °C), metal salt (Al 2 (SO 4 ) 3 ), and ion ratio (γ = 15). Under this condition, the volatilization rates of heavy metals (As, Cd and Zn) decreased remarkably. [ABSTRACT FROM AUTHOR]

Signal propagation can be blocked when the axon is injured or ion channels are blocked by certain drug, and thus signal communication between neurons can be interrupted. It is found that defects could be induced in the injured area of the axon, and the local heterogeneity can emit continuous pulses or wave fronts. In this paper, a weak electric field is imposed on the neuron to suppress the blocking of the defects on signal propagation. It is found that appropriate electric field can help signal propagate along the axon even the electric field is imposed on a local area. Its potential mechanism could be that the local electric field can suppress the wave emitting from the defects and thus the injured area can be bridged to transmit the blocked signals by adding gradient forcing along the axon. [ABSTRACT FROM AUTHOR]

To study the effect of erosion on coal microstructure and its oxidation characteristics, eroded coals were prepared by eroding coal samples in an acidic aqueous solution for 30 days, 90 days and 180 days, respectively. The microcrystalline structure, pore structure and active groups distribution of coal samples were studied using X-ray diffractometer, low-temperature N 2 adsorption and infrared spectra. Temperature-programmed experiment was used to analyze the oxidation characteristics of raw coal and eroded coals. The results reflected that the number of aromatic layers and coalification degree of eroded coal are reduced compared with raw coal. The average pore diameter increases, which promotes oxygen transportation in coal pores. Under the erosion effects, the content of active groups such as hydroxyl (–OH), methylene (–CH 2), and methyl (–CH 3) in coal increases. Eroded coals, especially the coal eroded for 180-day demonstrate more oxygen consumption and CO production than raw coal during the oxidation process, and their apparent activation energies decrease. Besides, the enhancement mechanism of eroded coal's oxidation activity is expounded from the aspects of the increase of active sites and the improvement of pore structure. In brief, erosion effect increases the spontaneous combustion tendency of coal. • The effect of weak acid erosion with different durations on coal oxidation behavior was studied. • Changes of coal physicochemical structure after erosion effect were studied. • The apparent activation energy of eroded coal decreases during low-temperature oxidation. • Mechanism for easier oxidation of dried eroded coal was expounded. [ABSTRACT FROM AUTHOR]

A new copper-based bulk form diluted magnetic semiconductor (DMS) (Ba 1− x K x )(Cu 2− x Mn x )Se 2 ( x =0.075, 0.10, 0.125, and 0.15) with T C ∼18 K has been synthesized. K substitution for Ba introduces hole-type carriers, while Mn substitution for Cu provides local spins. Different from previous reported DMSs, this material crystallizes into orthorhombic BaCu 2 S 2 -type crystal structure. No ferromagnetism is observed when only doping Mn, and clear ferromagnetic transition and hysteresis loop have been observed as K and Mn are codoped into the parent compound BaCu 2 Se 2 . [ABSTRACT FROM AUTHOR]

The objectives of this study were (i) to determine the stock and distribution of soil organic carbon (SOC) and the quantity and quality of fine root; and (ii) the correlation between SOC stock and fine root quantity and quality in soils of artificial and natural vegetation in the Loess Plateau. Three vegetation types (grassland, shrubland and woodland) and two restoration approaches (artificially and naturally restored from cropland) were investigated in the Yangou watershed of the Loess Plateau. SOC stock, fine root biomass and root C/N ratio at the 0–20, 20–40, 40–60, 60–80, and 80–100 cm depths were determined. The mean SOC stock of natural vegetation at the 0–100 cm depth was significantly greater than that of artificial vegetation, with an increase of 100% for woodland, 15% for shrubland, and 23% for grassland. Natural vegetation restoration led to a significantly greater SOC stock up to a depth of 100 cm for woodland, 40 cm for shrubland, and 40 cm for grassland. The fine root biomass of natural vegetation at the 0–100 cm depth was also significantly greater than that of artificial vegetation, with an increase of 170% for woodland, 140% for shrubland, and 20% for grassland. Natural vegetation restoration led to a significantly greater fine root biomass up to a depth of 100 cm for woodland, 60 cm for shrubland, and only 20 cm for grassland. There was a significant linear correlation between SOC stock and fine root biomass. Thus, natural vegetation restoration could lead to a significantly greater SOC stock, fine root biomass, and fine root C/N ratio than the artificial vegetation restoration. Fine root was an important factor influencing the differences in the SOC stock between artificial and natural vegetation. [ABSTRACT FROM AUTHOR]

Application of phosphorus (P) fertilizers to P-deficient soils can also result in P accumulation. In this study, soil P status and P uptake by apple trees were investigated in 5-, 10-, and 15-year-old orchards in the semi-arid Loess Plateau, China, and subset soils with different soil P statuses (14–90 Olsen-P mg kg−1) were selected to evaluate the characteristic P adsorption. Due to the low P-use efficiency (4–6%), total soil P increased from 540 mg kg−1 to 904 mg kg−1, Olsen-P ranged from 3.4 mg kg−1 to 30.7 mg kg−1, and CaCl2-P increased from less than 0.1 mg kg−1 to 0.66 mg kg−1 under continuous P fertilization. The P sorption isotherms for each apple orchard were found to fit the Langmuir isotherm model (R2 = 0.91–0.98). K (binding energy) and Qm (P sorption maximum) decreased, whereas DPS (degree of phosphorus sorption) increased with increasing P concentration. CaCl2-P increased significantly with the increase of Olsen-P, especially above the change point of 46.1 mg kg−1. Application of surplus P could result in P enrichment in P-deficient soil which has high P fixation capacity, thus posing a significant environmental risk. [ABSTRACT FROM AUTHOR]

Understanding the temperature sensitivity of soil respiration ( Q 10 ) and its controlling factors plays an important role in accurately estimating soil respiration and carbon cycling in agro-ecosystems. This manuscript presents a case study on how the Q 10 value for soil respiration changes with soil temperature and moisture in the rotation phases. In a three-year crop rotation system (wheat/wheat/millet/pea) in a semi-arid region of China, the soil respiration rate, temperature and moisture were measured under different crop phases from July 2010 to June 2013. The soil respiration rate was significantly lower in the winter wheat phase (1.63 μmol m −2 s −1 ) than the millet phase (2.40 μmol m −2 s −1 ) and pea phase (2.21 μmol m −2 s −1 ). However, the Q 10 value was significantly higher in the wheat phase (2.76) than in the millet phase (1.85) and pea phase (1.47). The relationship between the Q 10 values and soil temperature followed an exponential decay function in the rotation system, and the Q 10 value was stable (1.8) with no obvious variation when the temperature exceeded 15 °C. The Q 10 value tended to increase with soil moisture until reaching a threshold of 14.7% soil moisture and then declined. Our results indicate that temperature-respiration empirical models should be parameterized according to crop type in the rotation phases, especially when estimating soil respiration in cold-resistant crops under global warming. [ABSTRACT FROM AUTHOR]

A better understanding of the response of soil respiration to land-use conversion has important practical implications for ecological restoration in degraded regions. In this study, in situ soil respiration was monitored in a typical land-use sequence on a ridge slope in Wangdonggou watershed of the Loess Plateau, China, during a three-year period from 2011 to 2013. The land-use conversion sequences included cropland (control), apple orchard, grassland, and woodland. The results clearly showed that soil respiration and temperature sensitivity ( Q 10 ) varied significantly with land-use conversion. Soil respiration was decreased by 10% after conversion of cropland to orchard, and increased by 7–46% after conversion of cropland to grassland and woodland. Q 10 was increased by 19% after conversion of cropland to woodland, and decreased by 9–26% after conversion of cropland to grassland and orchard. Soil respiration increased linearly with soil organic carbon (SOC) storage and fine root biomass (<2 mm). The results indicated that root biomass and SOC storage were the major factors influencing Q 10 after conversion of cropland to non-natural ecosystem, and substrate quality or root system adaptability may be the real reason for the difference in Q 10 after conversion of cropland to natural grassland ecosystem. Although soil temperature and moisture significantly influenced soil respiration among the four typical land-use types, their difference derived from land-use conversions could not well explain the difference in soil respiration among land-use conversions. In conclusion, the increases in SOC storage and fine root biomass were the major factors influencing soil respiration among land-use conversions. Thus, conversion of cropland to natural grassland seemed to be the most effective integrated small watershed management to increase soil carbon storage and decrease CO 2 concentration in the loess regions of China. [ABSTRACT FROM AUTHOR]

Understanding the response mechanisms of litter respiration to soil moisture in water-limited semi-arid regions is of vital importance to better understanding the interplay between ecological processes and the local carbon cycle. In situ soil respiration was monitored during 2010–2012 under various conditions (normal litter, no litter, and double litter treatments) in a 30-year-old artificial black locust plantation (Robinia pseudoacacia L.) on the Loess Plateau. Litter respiration with normal and double litter treatments exhibited similar seasonal variation, with the maximum value obtained in summer (0.57 and 1.51 μmol m−2s−1 under normal and double litter conditions, respectively) and the minimum in spring (0.27 and 0.69 μmol m−2s−1 under normal and double litter conditions, respectively). On average, annual cumulative litter respiration was 115 and 300 g C m−2 y−1 under normal and double litter conditions, respectively. Using a soil temperature of 17°C as the critical point, the relationship between litter respiration and soil moisture was found to follow quadratic functions well, whereas the determination coefficient was much greater at high soil temperature than at low soil temperature (33–35% vs. 22–24%). Litter respiration was significantly higher in 2010 and 2012 than in 2011 under both normal litter (132–165 g C m−2 y−1 vs. 48 g C m−2 y−1) and double litter (389–418 g C m−2 y−1 vs. 93 g C m−2 y−1) conditions. Such significant interannual variations were largely ascribed to the differences in summer rainfall. Our study demonstrates that, apart from soil temperature, moisture also has significant influence on litter respiration in semi-arid regions. [ABSTRACT FROM AUTHOR]

The deformation behavior of the as-extruded Mg-Li-Al-Zn-Si alloy was studied by conducting a hot compression test, with a temperature range of 180–330 °C and a strain rate range of 0.01–10 s−1. The constitutive relationship of flow stress, temperature, and strain rate was expressed by the Zener–Hollomon parameter and included the Arrhenius term. By considering the effect of strain on the material constants, the flow stress at 240–330 °C could be precisely predicted with the constitutive equation (incorporating the influence of strain). A processing map was established at the strain of 0.7. The unsafe domains that are characterized by uneven microstructures were detected at low temperatures (<230 °C) or high temperatures (>280 °C), with high strain rates (>1 s−1). The optimum hot deformation region was obtained at a medium temperature (270–300 °C), with a peak power dissipation efficiency of 0.44. The microstructural evolution in different domains is investigated. The unstable domains are characterized by a non-uniform flow behavior and uneven microstructure. The observation showed that the dynamic recrystallization (DRX) process could easily occur at the safe domain with high power dissipation efficiency. For the α-phase, some features of continuous dynamic recrystallization can be found. The triple points serve as prominent nucleation sites for the β-phase DRX grains and the growth in the grains was carried out by subgrain boundary migration. The microstructure exhibits characteristics of discontinuous dynamic recrystallization. [ABSTRACT FROM AUTHOR]

• Cu 2 (Zn,Mn)(Sn,Al)Se 4 are new bulk form DMSs with decoupled charge and spin doping. • Only when Mn and Al are doped simultaneously can ferromagnetic ordering form. • Over or less of carriers for fix Mn concentration are both harmful to ferromagnetism. • Cu 2 (Zn,Mn)(Sn,Al)Se 4 have a negative magneto-resistance effect. We report the successful synthesis and characterization of a diluted magnetic semiconductor Cu 2 (Zn,Mn)(Sn,Al)Se 4 with stannite structure. 15% of Mn doping into the quaternary semiconductor Cu 2 ZnSnSe 4 does not induce any type of magnetic ordering. Only when Al is codoped with Mn, is ferromagnetic transition observed in Cu 2 (Zn,Mn)(Sn,Al)Se 4. Our results demonstrate that Mn substitution for Zn introduces local moments, while Al substitution for Sn introduces carriers, respectively. Both spins and carriers are crucial in the formation of ferromagnetic ordering in Cu 2 (Zn,Mn)(Sn,Al)Se 4. [ABSTRACT FROM AUTHOR]

Abstract: Nitrogen (N) and precipitation are the main limiting factors in food production under rain-fed cropping systems in arid and semiarid regions. A long-term field experiment was conducted from 1984 to 2009 in the Changwu State Key Agro-Ecological Experimental Station of the Loess Plateau, China, to study interactions between precipitation and N fertilization. Winter wheat (Triticum aestivum L.) was grown with N fertilization at 0, 45, 90, 135, and 180kgNha−1. With 25-year N fertilization, soil organic carbon and total N were increased by 18% and 26%, respectively. Mean yields and precipitation use efficiency (PUE) levels with N fertilization were increased by onefold to twofold compared with unfertilized soils. Generally, during the period of 1984–2009, grain yields with 45–`180kgN ha−1 increased at the rate of 38–49kgha−1 year−1 (p <0.05), whereas PUE increased at the rate of 0.071–0.088kgmm−1 year−1. These increases over time are largely attributable to improvements in soil organic carbon and total N. Variations in yield were proportionally reduced by N fertilization, but heavily depended on the fluctuation of precipitation. Grain yields with 45–180kgN ha−1 decreased by approximately 10%–45% (p <0.05) in the dry years (drought index<−0.35) compared with the normal years, whereas significant increases were not detected in the wet years (drought index>0.35). Grain yields with 90–180kgN ha−1 were positively correlated (p <0.05) with fallow season precipitation, but insignificantly correlated with growing season precipitation. The optimum N fertilization rates in the dry, normal and wet years increased following an increasing sequence of 45, 135 and 180kgNha−1. These results have significant implications for optimizing N fertilization and maximizing yield and PUE in rain-fed cropping systems in arid and semiarid regions. [Copyright &y& Elsevier]

Abstract: The hot deformation behavior of Zn82.7–Al10.2–Cu2.1 (in wt.%) was investigated by means of hot compression tests in the temperature range of 180–330°C and strain rate range of 0.01–10s−1. Processing maps were developed on the basis of experimental data and using the principles of the dynamic materials model (DMM). The results show that the maximum stress decreases with decreasing strain rate and increasing temperature, and that the activation energy is about 141.895kJ/mol. It is found that the strain has insignificant effect on the power dissipation maps. The maps exhibit two domains. The first domain occurs in the temperature range of 218–270°C and strain rate range of 0.04–1.2s−1 with the peak efficiency of 0.53. The second domain occurs in the temperature range of 290–330°C and strain rate range of 0.01–0.18s−1 with the peak efficiency of 0.58. Microstructural observations reveal that the partial dynamic recrystallization (DRX) of the Zn-rich phase occurs in the first domain and the full DRX of that occurs in the second domain. The dendritic structure is partially fragmented and elongated within the eutectic matrix and some initial laminar Al-rich phase is transformed into a spherical shape in the two domains. The large regime of flow instability is observed at the higher strain rates and all the tested temperatures with strain higher than 0.3. It expands when strain is increased. The flow instability predicted by processing maps is manifested as adiabatic shear bands, micro-cracks and macro-shear cracks. [Copyright &y& Elsevier]

Hot compression tests of the commercial Inconel 625 were performed in the temperature range of 950-1200 °C and strain rate range of 0.01-10 s. The flow behavior and processing maps were investigated using the corrected flow stress data to eliminate effects of the friction and adiabatic heating. The processing maps have exhibited a domain in the temperature range of 1100-1200 °C and strain rate range of 0.01-10 s corresponding to the higher efficiency of power dissipation. Microstructural observations reveal that the full dynamic recrystallization (DRX) occurs in this domain, which is optimum processing window for hot working to obtain a homogeneous microstructure. DRX grain growth occurs in the temperature range of 1150-1200 °C and strain rate range of 0.01-0.1 s. In view of the refined and uniform grains obtained by hot deformation, the finish forming processing should be selected the deformation conditions in which the full DRX occurs without the grain growth. The small regimes of flow instability are noticed at temperature below about 970 °C at the different strains. The material undergoes flow instability manifesting as bands of flow localizations and high density deformation twins. In addition, it is found that the undissolved second-phase particles and carbides can promote the DRX processing and be helpful to restrict the DRX grain growth. [ABSTRACT FROM AUTHOR]

Aims: Concerns over food security and global climate change require an improved understanding of how to achieve optimal crop yields whilst minimizing net greenhouse gas emissions from agriculture. In the semi-arid Loess Plateau region of China, as elsewhere, fertilizer nitrogen (N) inputs are necessary to increase yields and improve local food security. Methods: In a dryland annual cropping system, we evaluated the effects of N fertilizers on crop yield, its long-term impact on soil organic carbon (SOC) concentrations and stock sizes, and the distribution of carbon (C) within various aggregate-size fractions. A current version (RothC) of the Rothamsted model for the turnover of organic C in soil was used to simulate changes in SOC. Five N application rates [0 (N0), 45 (N45), 90 (N90), 135 (N135), and 180 (N180) kg N ha] were applied to plots for 25 years (1984-2009) on a loam soil (Cumulic Haplustoll) at the Changwu State Key Agro-Ecological Experimental Station, Shaanxi, China. Results: Crop yield varied with year, but increased over time in the fertilized plots. Average annual grain yields were 1.15, 2.46, 3.11, 3.49, and 3.55 Mg ha with the increasing N application rates, respectively. Long-term N fertilizer application increased significantly ( P = 0.041) SOC concentrations and stocks in the 0-20 cm horizon. Each kilogram of fertilizer N applied increased SOC by 0.51 kg in the top soil from 1984 to 2009. Using RothC, the calculated annual inputs of plant C (in roots, stubble, root exudates, etc.) to the soil were 0.61, 0.74, 0.78, 0.86, and 0.97 Mg C ha year in N0, N45, N90, N135 and N180 treatments, respectively. The modeled turnover time of SOC (excluding inert organic C) in the continuous wheat cropping system was 26 years. The SOC accumulation rate was calculated to be 40.0, 48.0, 68.0, and 100.0 kg C ha year for the N45, N90, N135 and N180 treatments over 25 years, respectively. As aboveground biomass was removed, the increases in SOC stocks with higher N application are attributed to increased inputs of root biomass and root exudates. Increasing N application rates significantly improved C concentrations in the macroaggregate fractions (>1 mm). Conclusions: Applying N fertilizer is a sustainable practice, especially in carbon sequestration and crop productivity, for the semiarid Loess Plateau region. [ABSTRACT FROM AUTHOR]

Abstract: The hot deformation behavior of Inconel 690 has been investigated by means of hot compression tests in the temperature range of 950–1200°C and strain rate range of 0.001–10s−1. The results show that the maximum stress decreases with decreasing strain rate and increasing temperature, and the activation energy is about 380.215kJ/mol. Processing maps developed on the basis of experimental data and using the principles of the dynamic materials model exhibited two domains. The first domain occurs in the temperature range of 970–1120°C and strain rate range of 0.03–3.3s−1, with a peak efficiency of power dissipation of 0.39. The second domain occurs in the temperature range of 1150–1200°C and strain rate range of 0.003–0.1s−1, with a peak efficiency of power dissipation of about 0.37. Microstructural observations revealed that the full dynamic recrystallization (DRX) occurred in these two domains. In the first domain, the undissolved carbides assisted in nucleating DRX and restricted the coarsening of the full DRX grains and the refined grains were obtained. A small regime of flow instability was noticed at low temperature and high strain rate. [Copyright &y& Elsevier]

Abstract: The reaction of a mixture of sodium cyclopentadienide and the monolithium salt or dilithium salt of 2,2-bis(indenyl)propane with FeCl2 leads to the mononuclear complex [(η5-C5H5)Fe(η5-ind-C(CH3)2-ind)] (ind=1-indenyl) (1) and the dinuclear complex [{(η5-C5H5)Fe(η5-ind)}2C(CH3)2] (2), respectively. [(η5-Me5C5)Fe(tmeda)Cl] reacts with dilithium 1,1′-biindenyl under formation of [{(η5-Me5C5)Fe}2(μ-η5:η5-1,1′-biind)] (4). Due to the annelated arene rings of the η5-indenyl ligands, 2 and 4 may act as 4-electron donor ligands, as exemplified by the reaction with the triple-decker complex [{(η5-Me5C5)Co}2(μ-η6:η6-toluene)], which afforded the tetranuclear dimer of triple-decker complexes [{(η5-C5H5)Fe(η5-Me5C5)Co(μ-η5:η4-1-ind)}2C(CH3)2] (3) and the trinuclear complex [{(η5-Me5C5)Fe}2(η5-Me5C5)Co(μ3-η5:η4:η5-1,1′-biind)]·Et2O (5 ·Et2O) by replacement of the central toluene deck, respectively. The [(η5-Me5C5)Co] fragments of 3 and 5 are bonded via the six-membered rings of the indenyl ligands in a η4-fashion. Caused by the coordination to the Co atoms the six-membered rings lose their planarity and adopt a butterfly structure. The coordination geometry of the Fe atoms is similar in all five complexes. Each Fe atom is coordinated by the C atoms of one of the five-membered rings of the indenyl ligands in a slightly distorted η5 manner (η3 +η2-coordination) and by a cyclopentadienyl ligand in a regular η5-fashion. The structures of 3 and 5 represent the first examples of slipped triple-decker complexes which comprise indenyl ligands in a μ-η5:η4 coordination mode. [Copyright &y& Elsevier]

Abstract: The title compounds 3 and 4 were synthesized by reaction of 1,1′ ferrocenylenediol with the Co triple decker compounds [{(η5-Me5C5)Co}2(η6:η6-toluene)] and [{(η5-EtMe4C5)Co}2(η6:η6-toluene)], respectively. The central Co atom of 3 is coordinated by five O atoms in a square-pyramidal manner. The remaining two Co atoms of 3 are coordinated to a Me5C5 ligand in a η5-fashion and by the two O atoms of two 1,1′ ferrocenylenediolato ligands which serve as chelating ligands. In 4, the central Co atom is coordinated to all six O atoms of three ferrocenylenediolato ligands in a trigonal-prismatic manner, whereas the two other Co atoms are coordinated by an EtMe4C5 ligand in a η5-fashion and by three O atoms of three ferrocenylenediolato ligands resulting in an overall tripoidal structure for 4. [Copyright &y& Elsevier]

The inhibitory effects of compound antioxidants (l -ascorbic acid (VC) and tea polyphenols (TP)) on coal oxidation were studied. The characteristics of coal oxidation was investigated by temperature-programmed experiments. The changes of active groups in coal were confirmed by Fourier-transform infrared spectroscopy. Quantum chemical theory was used to explore the reaction mechanism. Experimental results showed that compound antioxidants exhibit significant synergistic inhibition effect on coal oxidation. The apparent activation energy of coal oxidation increases by 16.23 kJ/mol for the addition of 6 wt% compound antioxidants (TP:VC = 2:1). The content of aliphatic hydrocarbons, –OH, C O and COOH in the antioxidant-treated coal decreases, while that of ether bond and aromatic bond increases. H15 of VC or H48 of epigallocatechin gallate (the main component of TP) can readily scavenge oxygen-containing radicals and inhibit the production of active groups in coal. Water-soluble antioxidants can be evenly dispersed on the coal surface, which provides an environment-friendly and efficient approach to preventing coal spontaneous combustion. • The mixture of VC and TP has a synergistic inhibitory effect on coal oxidation. • The content of active functional groups in coal treated with antioxidants is reduced. • The inhibitory mechanism of antioxidants on active radicals in coal is explored by quantum chemical theory. • Inhibitory effect is realized by eliminating oxygen-containing radicals and interrupting the generation of active groups. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multi-color fluorescence nanosensor based on Lap was manufactured. • It can realize the detection of tetracycline from 30 nM to 54 μM. • It was highly desirable for fulfilling the requirement for food quality. • Tetracycline can be recognized by chromaticity analysis APP on the smartphone. • It provided the possibility for the application in the field of intelligent devices. The emergence of "superbugs", which can cause great panic, has been proved to be related to the pollution of antibiotics in the environment water and food. It is of great research value to develop a portable, on-site and simple method for sensitive and selective detection of antibiotics. In this work, a laponite-based dual-channel fluorescent nanoprobe for the detection of tetracycline (TC) was manufactured through a simple assembly process. The nanoprobe can detect TC within two concentration channel from as low as 30 nM up to 54 μM with a detection limit of 9.5 nM, which met the needs in various analytical samples and showed excellent selectivity over various interferers. More significantly, the paper-based and glove-based visual probes were devised for the detection of TC by multi-color fluorescence change. And the tetracycline was also measured in milk, honey and lake after post-treatment of the samples. Combined with smartphone chromaticity analysis application (APP), the portable and disposable detection of TC can be realized. In addition, according to the fluorescence color change of the probe corresponding to the concentration of TC, two logic gates were also designed, which provided the possibility for the application of the probe in the field of smart devices. [ABSTRACT FROM AUTHOR]

Projected increases in the frequency and magnitude of extreme precipitation profoundly impact terrestrial ecosystems. However, the response of soil respiration to changing precipitation patterns has not been systematically investigated, especially in arid and semi-arid areas. Precipitation amounts of 300 and 600 mm (T300 and T600) were set to simulate normal and extremely wet summers, respectively, and were individually conducted by wetting soils in a series of sub-events—10 or 100 mm (P10, P100)—over equal time intervals. Maize straw (1300 kg ha−1) and N fertilization (200 kg N ha−1) were applied in parallel to extend our simulation to natural cropland conditions. Soil respiration pulses were observed after T300-P100, and inhibited effects occasionally occurred 1 day after T600-P100, primarily because frequent and harsh storms in T600-P100 induced saturation stress on soil respiration. Cumulative soil respiration in T600 was greater than that in T300, owing to prolonged suitable water conditions for soil respiration. Similarly, for the same total precipitation amount, P100 produced 40–44% more soil respiration than P10. Applying N and maize straw did not change response trends but produced different magnitudes of response to changing precipitation patterns. Maize straw significantly stimulated soil respiration, and this effect became more evident in P100 with improved water conditions, producing a 122–185% increase in cumulative soil respiration. Nitrogen slightly inhibited soil respiration; this effect was enhanced when maize straw was also added but was insignificant. Cumulative soil respiration was significantly correlated with β- d -glucosidase and soil microbial biomass carbon content. Such soil respiration responses highlight the need to accurately account for soil respiration contributions when projecting global carbon cycling in future climate scenarios. • Extreme precipitation events lead to soil respiration pulses, occasionally inhibiting and enhancing soil respiration rates. • Extreme precipitation patterns greatly enhanced the cumulative soil respiration. • Straw addition significantly amplified the response of soil respiration to extreme precipitation patterns. • N showed minor effects on soil respiration under extreme precipitation patterns. [ABSTRACT FROM AUTHOR]

For the nonlinear materials, not only the ratio p of the imaginary to the real part of the third-order nonlinear susceptibility but also the finite aperture size S exert a great influence upon the appearance of a peak on the Z-scan transmittance curve. This article investigates the p dependence of the critical aperture size S[sup c], which determines whether a transmittance peak occurs or not, and the dependence of the critical value pC on the parameter S for the thin-sample and low irradiance limits with a Gaussian beam. These results may be applied to the adjustment of experimental conditions at all times and the assessment of the correctness of data analysis. The experiment with CS[sub 2] seeking the critical value S[sup c] has verified above results. [ABSTRACT FROM AUTHOR]

• The effect of aqueous solutions with different pH values on coal oxidation behavior was studied. • Erosion process promotes the evolution of fine-mesopores to mesopores and macropores. • The content of active functional groups in eroded coal increases, especially under effect of acid erosion. In order to study the effect of aqueous solutions with different pH values on coal oxidation behavior, coal samples were eroded in aqueous solution of various pH values (4, 5, 7 and 8) for 30 days and to study its microstructure change and oxidation behaviors. The pore structure and functional groups were characterized by low-temperature N 2 adsorption and Fourier transform infrared spectroscopy. The oxidation characteristics of coal were investigated by temperature-programmed experiments. Compared with raw coal, larger average pore diameter and pore volume, more active functional groups, such as methyl, methylene, hydroxy and ether, were found in the eroded coal. Among them, the microstructure of coal eroded in acid water changes most obviously. Eroded coal samples have more pores with diameter > 20 nm and an obvious increase in particle surface roughness, which facilitates the adsorption and transportation of O 2 in coal body. The O 2 consumption and CO production of dried eroded coal, especially eroded in aqueous solution with pH = 4, are more than those of raw coal, and its apparent activation energy decreases both in the slow oxidation stage and the fast oxidation stage, which indicates that the eroded coal is more prone to spontaneous combustion. [ABSTRACT FROM AUTHOR]

Enhanced efficiency nitrogen fertilizers (EENFs) have provided opportunities for the simultaneous mitigation of nitrous oxide (N 2 O) emissions and increases in crop productions. However, the practice of combining EENFs with optimal fertilization under conditions of misaligned water and fertilizer inputs in rain-fed spring maize systems remains inadequately understood. This study aims to determine the factors controlling N 2 O emissions under the soil climatic conditions in rain-fed plastic mulching cropping systems treated with different nitrogen (N) fertilization rates and EENFs, and to determine the most effective N fertilization measure to reduce N 2 O emissions while maintaining crop yields. A 3-year field experiment was conducted in a spring maize system located in the semiarid rain-fed region of the Loess Plateau, applying two types of EENFs: a nitrification inhibitor dicyandiamide (DCD) and a slow-release fertilizer (SRF). It comprised five fertilization treatments: unfertilized (CK), conventional N rate (CON, 200 kg N ha−1), optimal N rate (OPT, 160 kg N ha−1), OPT with the addition of DCD (OPT+DCD), and OPT using SRF (OPT-SRF). The average annual cumulative N 2 O emissions over the 3-year experimental period ranged from 0.74 to 1.87 kg N 2 O-N ha–1. Fertilizer N contributed 26−60% to annual N 2 O emissions. The highest N 2 O fluxes (50–161 μg N 2 O-N m–2 h–1) typically occurred within the initial 10 days following fertilization, likely induced by strong nitrification processes, constituting 12–19% of the annual N 2 O emissions during this brief period. In comparison to the CON treatment, the OPT, OPT+DCD, and OPT-SRF treatments resulted in significant reductions in annual N 2 O emissions of 24%, 46%, and 34%, respectively, without causing any significant decrease in maize grain yields. The application of DCD led to increased ammonium (NH 4 +-N) concentrations while reducing nitrate (NO 3 –-N). Conversely, using SRF resulted in a decrease in both NH 4 +-N and NO 3 –-N concentrations. Using EENFs at the ideal fertilization rate significantly curtailed yearly N 2 O emissions without adversely affecting maize yields in a rain-fed plastic mulching spring maize system prevalent in the Loess Plateau. Most N 2 O emissions occurred post-fertilization, with rainfall events further influencing these emissions. Our findings recommend the incorporation of nitrification inhibitors, such as DCD, as the most effective fertilizer measure for reducing N 2 O emissions in the rain-fed region of the Loess Plateau. [ABSTRACT FROM AUTHOR]

Subsoil exposure due to factors including erosion and terracing, evidently decreases soil organic carbon storage and productivity, but the responses of bacterial communities and their carbon dynamics remain unclear. Soils from 0–20 cm, 20–60 cm and 60–100 cm were collected from three 100 cm profiles in bare land on the Loess Plateau, and incubated in buried pots for a year (July 2016 to July 2017) to simulate subsoil exposure, with ongoing monitoring of the microbial mineralization rate of soil organic carbon (K c), using Li-Cor 8100. At the end of the incubation period, the exposed soil and the in situ control soil were sampled to investigate changes in bacterial community composition, as represented by 16S rRNA, and the activities of enzymes involved in soil carbon cycling. Both copiotrophic (Actinobacteria and Alphaproteobacteria) and oligotrophic (Thermoleophilia) groups were stimulated in the exposed vs. control soil at 20–60 and 60–100 cm. The exposed vs. control soil from 60 to 100 cm produced the greatest bacterial responses, such as greater diversity and altered keystone groups (Thermoleophilia vs. unidentified Acidobacteria). Enzyme activities were greater in the exposed vs. control soil at both 20–60 cm (β-D-xylosidase and cellobiohydrolase) and 60–100 cm (β-D-xylosidase and β-D-glucosidase). The exposed soil from 20–60 cm and 60–100 cm had lower K c and Q 10 values than those at 0–20 cm. Our findings revealed the existence of bacterial depth-specific responses to subsoil exposure, and highlight the effect of anthropogenic soil redistribution on soil carbon flux and its potential responses to future climate change. Unlabelled Image • Subsoil exposure had depth-specific effect on bacterial community and activities. • Both copiotrophic and oligotrophic groups increased in exposed vs. control soil. • Bacterial community composition altered at 60–100 cm in exposed vs. control soil. • Enzyme activities were greater at 20–60 and 60–100 cm in exposed vs. control soil. • The exposed subsoils had consistently lower K c and Q 10 compared with the topsoil. [ABSTRACT FROM AUTHOR]

Despite the pivotal functional roles dominating the pace of nutrient cycles in terrestrial ecosystems, soil fungal communities at erosional and depositional sites have not been comparatively investigated when assessing the ecosystem stability of eroding landscapes. In this study, soil fungal communities in topsoil (0–5 cm) and subsoil (5–10 cm) on simulated eroding slopes of three slope gradients, i.e., 5°, 10°, and 20°, and in the corresponding depositional zones were examined from 2015 to 2017 in the region of the Chinese Loess Plateau. The results showed that, compared with that in the 5° reference slopes, soil fungal richness in the topsoil and subsoil of the 10° and 20° eroding slopes was 11.8–24.9% lower. However, the richness increased by 2.3–22.7% in the subsoil of the depositional zones, yet not in the topsoil. Soil fungal community compositions in both topsoil and subsoil differed between depositional zones and reference slopes but not between eroding slopes and reference slopes. The differentiation of fungal richness and community compositions between eroding slopes and depositional zones increased with slope gradients, regardless of the topsoil and the subsoil. Saprotrophic fungi levels were 22.5–48.0% lower and pathogenic fungi were 45.2–193.3% higher in the subsoil of the depositional zones with 10° and 20° slopes than in the subsoil of the 5° reference slopes. Soil fungal network on the eroding slope was more complex than that in the depositional zone, suggesting more extensive interactions of fungal taxa and higher community stability potential on eroding slopes. The decreasing soil moisture, organic matter, and other properties on the eroding slopes, in contrast with these properties increasing in the depositional zones, were responsible for the variations in fungal richness and community composition. The divergent responses of soil fungal communities to soil erosion and deposition emphasized the complexity and variability of fungal communities during the soil erosion-deposition processes. Unlabelled Image • Soil erosion decreased fungal richness in both topsoil and subsoil. • Deposition enhanced fungal richness in subsoil but not in topsoil • Fungal community composition in both topsoil and subsoil were altered by deposition rather than by erosion. • The relative abundance of saprotroph was decreased by deposition in contrast to pathotroph. • Eroding fungal networks were more complex than depositional fungal networks. [ABSTRACT FROM AUTHOR]

Tetracycline (TC) residues are harmful to the environment and human body, so it is necessary to develop a highly sensitive probe for rapid detection of tetracycline residues. In the present paper, a novel dye-doped porous metal–organic framework (UiO-66)-based multi-color fluorescent nano-probe was designed for sensitive ratiometric detection of tetracycline (TC). In this probe, dye-molecules doped UiO-66 was used as a fluorescent internal standard, and the externally grafted lanthanide Eu3+ complex was used as response signals. The fluorescence of the Eu3+ complex was selectively enhanced with increasing concentrations of TC, which was accompanied by a visual blue-to-red color switch. The nano-probe had a linear response between 0.1 and 6 μM with a lowest detection limit of 17.9 nM, which was much lower than the maximum residue limits set by the United States Food and Drug Administration (676 nM) and the European Union (225 nM). The applicability of this method in the analysis of actual samples was evaluated by the determination of TC in honey and milk samples, indicating satisfactory recovery and good reproducibility. In addition, a cost-effective paper-based probe for rapid and visual detection of TC was developed by fixing the nano-probe on filter papers. With the help of a smartphone camera to capture the fluorescence color, and chromaticity analysis software, the calculation and analysis of red (R) and blue (B) values can be realized, which has the potential for real-time visual detection of TC. [ABSTRACT FROM AUTHOR]

Acid treatment has been proven to effectively reduce the fracture initiation pressure in reservoirs, making it a viable method for stimulating deep tight sandstone reservoirs. However, the underlying mechanism of how sandstone pore structure and mechanical properties vary with acid treatment time remains unknown. Understanding this mechanism is crucial for studying the fracture initiation and propagation in tight sandstone reservoirs. In this study, to quantitatively analyze the changes in pore structure and mechanical properties of sandstone samples treated with acid for different times (0 h, 1 h, 2 h, 4 h, 6 h, 12 h, 24 h, 48 h, 72 h, 120 h, and 168 h), nuclear magnetic resonance and uniaxial compression tests were employed to examine these changes. The results revealed that the number of mesopores and macropores increased rapidly after 6 h and 48 h of acid treatment, respectively. Additionally, the permeability showed a significant increase after 24 h of acid treatment. This can be attributed to the gradual dissolution of intergranular cement, leading to the formation of new pores that connect with the existing pore network. The peak strength of sandstone undergoes stepwise changes with acid treatment time, which can be divided into three stages: stage I (0–6 h), stage II (12–72 h), and stage III (120–168 h). Under the influence of acid treatment and uniaxial compression, the damage and damage change rate of sandstone treated with acid for 24 h reached the minimum. Moreover, a variation mechanism for sandstone after acid treatment was proposed. [ABSTRACT FROM AUTHOR]

Numerous technological advancements in the 21st century depend on the creation of novel materials possessing enhanced properties; there is a growing reliance on materials that can be optimized to serve multiple functions. To efficiently save time and meet the requirements of diverse applications, high-throughput and combinatorial approaches are increasingly employed to explore and design superior materials. Among them, gradient thin-film deposition is one of the most mature and widely used technologies for high-throughput preparation of material libraries. This review summarizes recent progress in gradient thin-film deposition fabricated by magnetron sputtering, multi-arc ion plating, e-beam evaporation, additive manufacturing, and chemical bath deposition, providing readers with a fundamental understanding of this research field. First, high-throughput synthesis methods for gradient thin films are emphasized. Subsequently, we present the characteristics of combinatorial films, including microstructure, oxidation, corrosion tests, and mechanical properties. Next, the screening methods employed for evaluating these properties are discussed. Furthermore, we delve into the limitations of high-throughput preparation and characterization techniques for combinatorial films. Finally, we provide a summary and offer our perspectives. [ABSTRACT FROM AUTHOR]

• SrF( Zn 1 - 2 x Mn x Cu x )Sb is a new diluted magnetic semiconductor with highest Tc ∼ 40 K. • Doping only Cu into the parent compound SrFZnSb does not induce any type of magnetic ordering. • The antiferromagnetic interaction inhibits the ferromagnetism in high doping level. • SrF( Zn 1 - 2 x Mn x Cu x )Sb has a negative magneto-resistance effect. We report the synthesis and characterization of a new bulk form fluoride-antimonide diluted magnetic semiconductor SrF( Zn 1 - 2 x Mn x Cu x )Sb with ZrCuSiAs-type structure, which is the same quasi-two-dimensional crystal structure as that of 1111-type iron-based superconductors. Doping only Cu into the parent compound SrFZnSb does not induce any type of magnetic ordering. Only when Mn and Cu are codoped into Zn sites, where Mn substitution for Zn and Cu substitution for Zn introduce spins and carriers, respectively, can ferromagnetic ordering form. Bulk form samples SrF( Zn 1 - 2 x Mn x Cu x )Sb with x = 0.05, 0.075, 0.10 and 0.15 exhibit ferromagnetic transition, with highest T C ∼ 40 K for the doping level of x = 0.10. Iso-thermal magnetization measurements show that they have a relatively larger coercive field ∼ 8000 Oe. The electrical resistivity measurements indicate that SrF( Zn 1 - 2 x Mn x Cu x )Sb DMSs display semiconducting behavior, with the negative magneto-resistance effect up to 27% under 9 T at 2 K. [ABSTRACT FROM AUTHOR]

Highlights • ORG significantly increased surface soil total N contents and vegetable yield. • N leaching (9.8%–18.1% of N inputs) was the primary N loss pathway in three systems. • ORG markedly reduced yield-scaled nitrous oxide emissions and cumulative N leaching. Abstract A field experiment was conducted in the southern gully region of the Loess Plateau to study the effects of mulching measures on spring maize yield and nitrate accumulation in dryland areas under traditional tillage conditions. The study was performed to provide a scientific basis for spring maize planting and environmental protection in this area. The four treatments were non–mulching (CK), plastic film–mulching during the growth period (PM 1), plastic film–mulching during the fallow period (PM 2), and straw–mulching (JM). After 13 years of continuous application, the yield of spring maize, the nitrogen uptake by plants, and the nitrate nitrogen content at the harvest stage were measured. The results revealed that soil moisture content and water storage capacity of the three soil–mulching treatments were all higher than those of the non–mulching treatment. Soil water storage at a depth of 0–300 cm in the JM, PM 1 and PM 2 treatments was increased by 11.8%, 10.6% and 8.8%, respectively, compared with the CK treatment. Compared with the CK treatment, the mulching treatments significantly increased the aboveground biomass and grain yield of spring maize. The yield enhancement effect of the PM 1 treatment was the most significant, with a yield of 1.1 Mg ha-1 and an increase of 26.72%. In addition to the JM treatment, the accumulation of soil nitrate at a depth of 0–300 cm in the PM 1 and PM 2 treatments was less than that of the CK treatment, but the largest increase in soil nitrate (80.20% in the JM treatment) was observed at a depth of 0–100 cm. The results suggest that in the rainfed agriculture in the southern Loess Plateau, mulching cultivation can effectively increase the soil moisture content and water storage capacity. PM 1 , and PM 2 treatments could significantly reduce the content and accumulation of nitrate nitrogen in the deeper soil profile, and the three mulching measures could slow down the deep accumulation of soil nitrate nitrogen to a certain extent. [ABSTRACT FROM AUTHOR]

Highlights • In rainfed agriculture in the southern of Loess Plateau, mulching measures increased soil water content and water storage. • Plastic film-mulching during the growth period is the best way to increase the yield of corn. • This study revealed the soil nitrate nitrogen distribution and deep accumulation pattern in a rainfed agricultural area. • The results provide scientific guidance for reasonable fertilization and farming practices in future in this area. Abstract Field experiment was conducted in the southern gully region of the Loess Plateau to study the effects of different mulching measures on spring maize yield and nitrate leaching in dryland under the traditional tillage conditions, so as to provide a scientific basis for spring maize planting and environmental protection in this area. The four treatments included non-mulching (CK), plastic film-mulching (PM 1), plastic film-mulching in fallow (PM 2) and straw-mulching (JM). After 13 years of continuous application, the yield of spring maize, the nitrogen uptake by plants and the nitrate nitrogen content at the harvest stage were measured. The results showed that the soil moisture content and water storage capacity of three kinds of soil mulching treatments were all higher than those of non-mulching ones. Soil water storage in the range of 0 ∼ 300 cm of JM, PM 1 and PM 2 increased by 11.8%, 10.6% and 8.8% respectively compared with CK. Compared with CK, the mulching treatments significantly increased the aboveground biomass and grain yield of spring maize. The yield enhancement effect of PM 1 was the most significant, with a yield of 11,314.42 kg / ha and an increase of 26.72%. In addition to the JM treatment, the accumulation of soil nitrate nitrogen in the range of 0 ∼ 300 cm of PM 1 and PM 2 was less than that of CK, but the increase of nitrate nitrogen of 80.20% of JM treatment was in the range of 0 ∼100 cm. Therefore, in the rain-fed agriculture in the south of Loess Plateau, mulching cultivation can effectively increase the soil moisture content and water storage, improve crop growth. The yield enhancement effect of plastic mulching-film was the best. PM 1 , PM 2 could significantly reduce the content and accumulation of nitrate nitrogen in soil profile, and the three mulching measures could slow the deep leaching of soil nitrate nitrogen to a certain extent. [ABSTRACT FROM AUTHOR]

Land use and topography are two primary factors that affect the spatial distribution of soil organic carbon (SOC) at the watershed scale, particularly in areas of multiple land uses and complex topography on the Loess Plateau. The General Linear Model (GLM) combined with Duncan’s Multiple Range Test (DMRT) were used to conduct variance tests and evaluate the effects of topography (summit, sloping areas and gullies), land use (farmland, orchard, grassland, shrubland and woodland), and their interactions on the vertical and horizontal distributions of SOC at soil depths of 0–10, 10–20, 20–40, 40–60, 60–80 and 80–100 cm. The effects of land use intensified from the summits to the slope areas to the gullies. The SOC concentrations throughout the 100 cm-thick soil profiles in farmland in slope areas and gullies were, respectively, 45.4% ( P < 0.0001) and 55.2% ( P < 0.0001) greater than those on the summits (3.1 g kg −1 ). In slope areas, the SOC concentrations in shrubland and grassland exceeded those in farmland (4.5 g kg −1 ) by 52.1% ( P < 0.0001) and 15.8%, respectively. In addition, in the gullies, the mean SOC concentrations in shrubland and grassland exceeded those in farmland (4.8 g kg −1 ) by 80.6% ( P < 0.0001) and 50.7% ( P = 0.0039), respectively. The SOC concentrations in areas of semi-shaded slope aspects were greater than those in areas of semi-sunny aspects. The enhanced effect of topographic position on SOC may be attributed to the vegetation and the soil conditions associated with the land uses and to the interactions between these variables at the watershed scale. These results could enhance understanding of the effects of environmental factors and their interaction on the spatial variation of SOC in regions with complex topography. These conclusions could have important implications for ecosystem recovery through rational land use changes in the ecologically fragile areas of the Loess Plateau and for improving the accuracy of prediction of SOC in regions of complex topography and land use on the Loess Plateau. [ABSTRACT FROM AUTHOR]

• Release of CO and CO 2 at constant temperature with time follows two different rules. • C–H in side chains is oxidized into precursors of carbon oxides, C = O and –COO. • CO and CO 2 can be produced by stepwise decomposition at ambient temperature. • Production of CO and CO 2 by direct decomposition occurs only at high temperatures. Precursors of carbon oxides in coals are considered to be related to aldehyde group(–CHO) and carboxyl group (–COOH), but the way of decomposition of precursors to produce carbon oxides is not clear. Through theoretical analysis, experimental research and quantum chemical calculation at molecular scale, this paper explores the decomposition mode and products of carbon oxide precursors during coal spontaneous combustion (CSC). A programmed heating device was used to investigate the change rule of gas product concentration during the constant temperature oxidation of coals, and the microstructure of the coals was characterized by low-temperature nitrogen adsorption experiments (BET), X-ray Diffraction (XRD) and X-ray photoelectron spectrometer (XPS). The results of the study show that during coal oxidation, the inhomogeneous energy exchange between the coals and the external heat source results in the change of gas product concentration with time following two rules. BET experiments reveal that oxidation leads to the evolution of fine mesopores to macropores and an increase in the number of pores with diameters larger than 20 nm in the coals, which facilitates the transport of oxygen molecules through the pore structure. Within 200 °C, the microcrystalline structure of coals is basically unchanged, and the active structure C–C/C–H on the side chain is converted to –CHO and –COOH and then decomposed to produce carbon oxides. Quantum chemical calculation shows that the reaction energy barrier of carbonyl group and carboxyl group decomposed step by step to form carbon oxides is much smaller than that of direct decomposition, and carbon oxides and alkyl radicals can be produced even at room temperature by step decomposition. The research results provide theoretical guidance for the formation mechanism of carbon oxides during low temperature oxidation of coals. [ABSTRACT FROM AUTHOR]

Glioma is a serious fatal type of cancer with the shorter median survival period and poor quality of living. The overall 5-year survival rate remains low due to high recurrence rates. Glioma stem cells (GSCs) play the important roles in the development of gliomas. Examination of the numerous biomarkers or cancer-associated genes involved in the development or prevention of glioma may therefore serve the discovery of novel strategies to treat patients with glioma. Hypoxia induced by using CoCl2 application and 14-3-3β protein knockdown by specific small interfering RNA transfection were performed in GSCs both in vitro and in vivo to observe their role in glioma progression and metastasis occurrence by using western blot analysis and MTT assay. The results demonstrated that CoCl2 application enhanced the 14-3-3β protein expression and mRNA levels via the PI3K pathway in GSCs. Furthermore, hypoxia promoted GSC cell proliferation and activated the expression of proliferating cell nuclear antigen, which was inhibited following 14-3-3β knockdown. In addition, tumor growth in mice was enhanced by CoCl2 application but reversed following 14-3-3β knockdown, which also enhanced GSC cell apoptosis. In conclusion, the present study demonstrated that hypoxia promoted glioma growth both in vitro and in vivo by increasing the 14-3-3β expression via the PI3K signaling pathway. 14-3-3β and HIF-1α may therefore be considered as the potential therapeutic target to treat patients with glioma. [ABSTRACT FROM AUTHOR]

Abstract: Land use and topography strongly influence soil organic C (SOC) and N accumulation in eroded hilly regions. However, their combined effects and the underlying mechanism remain unclear. In this study, five land uses and three topographic positions across an eroded hilly watershed of the Loess Plateau were selected to investigate their effects on SOC and N accumulation. The restored grassland, shrubland and woodland (25 to 30years) increased SOC and total N by 32% to 119% in the slope and 17% to 81% in the gully, respectively compared with the cropland. These restored vegetation increased soil dissolved organic C (DOC) and microbial biomass C and N (MBC and MBN) by 1.1- to 3.0-fold in the slope and 30% to 108% in the gully, respectively. Similar increases were observed in soil aggregates, MBN/total N, soil C:N and microbial C:N ratios. These improvements were higher in the shrubland than in the other land uses. The SOC significantly decreased from the gully to the slope, and the magnitudes decreased in a sequence of cropland, grassland, shrubland and woodland. Soil DOC, total N, and MBN also decreased from the gully to the slope in the cropland, but remained unchanged in the grassland, shrubland, and woodland. Land use (P <0.05), topographic position (P <0.05), and their interaction (P <0.1) influenced SOC, total N, DOC, MBC, MBN, soil C:N and microbial C:N ratios. There were close relationships among soil aggregates, SOC and total N, and DOC, MBC and MBN. Therefore, land use, topographic position (erosion and deposition), and their interactions regulate SOC and N accumulation and their labile fractions in the eroded hilly region at a watershed scale. Our results suggested that converting cropland to shrubland is an initial strategy to restore degraded ecosystems and increase soil C sequestration in eroded hilly region of the Loess Plateau. [Copyright &y& Elsevier]

In order to study the influence of adsorptive gas on coal pore structures and mechanical strength, coal specimens were placed in a low-pressure environment of CH 4 or CO 2 for 30 days to ensure that the specimens were saturated and fully interacted with the gas. Low-pressure nitrogen adsorption, scanning electron microscope, X-ray diffraction, and uniaxial compressive strength tests were employed to study coal's microstructure change and strength characteristics. The results show that after CH 4 or CO 2 treatment, the proportion of macropores increases by 38.87% and 22.89%, and that of mesopores decrease by 6.34% and 3.73%, respectively, which indicates the evolution of mesopores to macropores. The microcrystalline structure parameters change obviously after long-term gas adsorption treatment. The values of d 002 and d 100 increase, while L c , L a , and M c 's values both decrease, resulting in a loose coal structure. Besides, a conceptual model is proposed to explain the evolution mechanism of pore structures under the effect of long-term gas adsorption. • The influence of gas adsorption effect on pore structure fractal dimensions of coal was studied. • Gas adsorption treatment promotes the evolution of mesopores to macropores. • The microcrystalline structure of adsorption-treated coal is loose. • A conceptual model to explain coal-pore structure evolution is established. [ABSTRACT FROM AUTHOR]

• Upstream has the highest prokaryotic alpha-diversity index. • Upstream had a larger clustered network in the < 63 μm fractions. • Varied sediment fractions during soil erosion altered the prokaryotic community. The transfer of particle-bound prokaryotes and substrates from slopes to rivers during soil erosion is a crucial dynamic process that greatly influences terrestrial biological and geochemical cycles. Particle size strongly affects the transport distance of suspended sediments and likely induces prokaryote and substrate variations along the course of the river. Previous studies have mainly focused on the spatial redistribution of soil prokaryotes, whereas the variation in prokaryotic diversity and community composition among different particle size-fractions in suspended sediments remain unclear. In this study, suspended sediments were collected at four plots (upstream, middle stream, downstream, and dam) along a river that runs through a valley. Sampled sediments were size-fractionated into > 63 μm and < 63 μm particles (referred to as small and large particle fractions hereafter), to identify the corresponding prokaryotic community composition, interactions, and functions. The richness index (Chao1 and observed species) and the diversity index (Shannon) of sediment-associated prokaryotic communities significantly decreased from upstream towards dam plots, except in the small particle fraction in downstream and dam plots. The highest β-diversity index value was found for the large particle fractions, while the geospatial contribution to β-diversity varied. The concentration of Proteobacteria in downstream (41.39 %) and dam (34.86 %) plots was lower than that in the upstream (47.65 %) and middle stream (45.90 %) plots. In contrast, Cyanobacteria (4.89 % and 6.75 %) and Verrucomicrobiota (5.98 % and 11.00 %) concentrations were greater in the downstream and dam plots, respectively, than those in the upstream (0.93 % and 2.43 %) and middle stream (3.37 % and 3.11 %) plots, respectively. Additionally, the concentrations of Verrucomicrobiota and Bacteroidota were significantly higher in the small particle fractions (2.26–8.12 % and 4.33–7.72 %) than those in the large particle fractions (2.03–5.94 % and 3.70–7.11 %). Compared to the other plots, upstream plots had a larger clustered network and a greater number of co-occurrences within the prokaryotic community in the bulk sediment and in the small particle fraction, whereas more complex interactions among prokaryotic communities were found in the large particle fraction from the dam plots. Soil organic carbon (SOC), total nitrogen (TN), and Olsen phosphorus were the three most influential factors, explaining 67.41 % of the variation in prokaryotic community. Proteobacteria and Myxococcota correlated negatively with SOC, TN, and Olsen P but positively with C = O. Conversely, Cyanobacteria and Verrucomicrobiota correlated positively with SOC, TN, and Olsen P but negatively with C = O. Functional groups linked to the biogeochemical cycling of carbon (methanol oxidation and methylotrophy) were found in high concentrations, whereas those linked to nitrogen (nitrogen and nitrate respiration) were found in low concentrations in upstream and middle stream plots. Reassembly of the sediment physicochemical characteristics among geospatial plots along the transport transect significantly altered the prokaryotic community composition and metabolic functional groups. [ABSTRACT FROM AUTHOR]

High-entropy ceramic films (HECFs) have become promising industrial materials due to their excellent mechanical and functional properties. Achieving the precise design of HECFs has been a hot topic in recent years. Herein, the CoCrFeMnNi alloy, one of the most classic high-entropy systems, is chosen as the model to reveal the phase formation, growth, and properties of HECFs. Films were fabricated by magnetron sputtering at various N 2 -to-total (N 2 + Ar) flow ratios (R N). Results show that the phase structure transformed from a semi-crystal phase to a single face-centered cubic (fcc) structure with increasing R N. Atomic migration ability affected by R N drives different growth processes, thereby constructing different microstructures, such as loose fiber structure and stacked particle structure. Moreover, the hardness exhibits a nonlinear relationship with interstitial solid solubility. Such unusual interstitial solid-solution strengthening behavior is attributed to the offset between solid-solution strengthening and grain boundary weakening as R N increases. A high hardness of 13.71 GPa and Young's modulus of 203.3 GPa are obtained in the (CoCrFeMnNi)N x film deposited at R N = 20 %. This work not only explores an unusual interstitial solid-solution strengthening behavior, but also sheds light on the future HECFs design. • Phase transforms from semi-crystal phase to fcc phase with increasing N content. • It is proved that an interstitial solid-solution structure was constructed in HECFs. • Different growth processes drive the formation of different microstructures. • An unusual interstitial solid-solution strengthening is observed in HECFs. [ABSTRACT FROM AUTHOR]

Abstract: Hot compression tests of Inconel 625 superalloy were conducted using a Gleeble-1500 simulator between 900°C and 1200°C with different true strains and a strain rate of 0.1s−1. Scanning electron microscope (SEM) and electron backscatter diffraction technique (EBSD) were employed to investigate the effect of deformation temperature on the microstructure evolution and nucleation mechanisms of dynamic recrystallization (DRX). It is found that the relationship between the DRX grain size and the peak stress can be expressed by a power law function. Significant influence of deformation temperatures on the nucleation mechanisms of DRX are observed at different deformation stages. At lower deformation temperatures, continuous dynamic recrystallization (CDRX) characterized by progressive subgrain rotation is considered as the main mechanism of DRX at the early deformation stage. However, discontinuous dynamic recrystallization (DDRX) with bulging of the original grain boundaries becomes the operating mechanism of DRX at the later deformation stage. At higher deformation temperatures, DDRX is the primary mechanism of DRX, while CDRX can only be considered as an assistant mechanism at the early deformation stage. Nucleation of DRX can also be activated by the twinning formation. With increasing the deformation temperature, the effect of DDRX accompanied with twinning formation grows stronger, while the effect of CDRX grows weaker. Meanwhile, the position of subgrain formation shifts gradually from the interior of original grains to the vicinity of the original boundaries. [Copyright &y& Elsevier]

Abstract: Hot compressions tests of Inconel 625 superalloy were conducted using a Gleeble-1500 simulator at different strains between 900°C and 1200°C with a strain rate of 0.1s−1. Optical microscope, transmission electron microscope and electron backscatter diffraction technique were employed to investigate the microstructure evolution and nucleation mechanisms of dynamic recrystallization. It was found that both the size and fraction of dynamically recrystallized grains increase with increasing deformation temperature. However, the size of dynamically recrystallized grains almost remains constant with increasing deformation strain. The dominant nucleation mechanism of dynamic recrystallization in Inconel 625 superalloy deformed at 1150°C is the discontinuous dynamic recrystallization, which is characterized by the bulging of the original grain boundaries accompanied with twining. The continuous dynamic recrystallization characterized by progressive subgrain rotation occurs simultaneously in dynamic recrystallization process, although it can only be considered as an assistant nucleation mechanism at the early stage of hot deformation. [Copyright &y& Elsevier]

Aims: Crop rotation plays an important role in changing soil microbial communities, which is critical to maintaining soil multifunctionality. However, limited data exist on the long term impact of crop rotations on soil multifunctionality and its link with soil fungal community in drylands.In a dryland field experiment with 30-year legume- and non-legume-based winter wheat rotations and winter wheat-fallow system, we investigated the soil multifunctionality (via cycling and pools of soil carbon and nitrogen) and the overall community and functional groups of soil fungi. The links between soil multifunctionality and fungal communities were also explored.We found that long-term crop rotation increased soil multifunctionality index and that of carbon cycle. Crop rotation shifted soil fungal community composition, and reduced the proportion of putative pathotrophs. The overall fungal community was almost equally explained by soil and plant variables, while fungal functional groups (i.e., saprotrophs and pathotrophs) were more affected by soil variables. The indicator taxa in the non-legume-winter wheat rotation were distinctly different from those in the legume-based winter wheat rotation soils, indicating that the non-legume-winter wheat rotation selects different fungal taxa from the legume-based winter wheat rotation. Moreover, the changes in community composition of soil fungi, putative saprotrophs and pathotrophs were related to soil multifunctionality and that of carbon and nitrogen cycles.Our results highlight that long-term crop rotations shape the soil fungal communities; the changes in soil fungi and fungal functional groups have potential to improve soil multifunctionality in the crop rotation systems in drylands.Methods: Crop rotation plays an important role in changing soil microbial communities, which is critical to maintaining soil multifunctionality. However, limited data exist on the long term impact of crop rotations on soil multifunctionality and its link with soil fungal community in drylands.In a dryland field experiment with 30-year legume- and non-legume-based winter wheat rotations and winter wheat-fallow system, we investigated the soil multifunctionality (via cycling and pools of soil carbon and nitrogen) and the overall community and functional groups of soil fungi. The links between soil multifunctionality and fungal communities were also explored.We found that long-term crop rotation increased soil multifunctionality index and that of carbon cycle. Crop rotation shifted soil fungal community composition, and reduced the proportion of putative pathotrophs. The overall fungal community was almost equally explained by soil and plant variables, while fungal functional groups (i.e., saprotrophs and pathotrophs) were more affected by soil variables. The indicator taxa in the non-legume-winter wheat rotation were distinctly different from those in the legume-based winter wheat rotation soils, indicating that the non-legume-winter wheat rotation selects different fungal taxa from the legume-based winter wheat rotation. Moreover, the changes in community composition of soil fungi, putative saprotrophs and pathotrophs were related to soil multifunctionality and that of carbon and nitrogen cycles.Our results highlight that long-term crop rotations shape the soil fungal communities; the changes in soil fungi and fungal functional groups have potential to improve soil multifunctionality in the crop rotation systems in drylands.Results: Crop rotation plays an important role in changing soil microbial communities, which is critical to maintaining soil multifunctionality. However, limited data exist on the long term impact of crop rotations on soil multifunctionality and its link with soil fungal community in drylands.In a dryland field experiment with 30-year legume- and non-legume-based winter wheat rotations and winter wheat-fallow system, we investigated the soil multifunctionality (via cycling and pools of soil carbon and nitrogen) and the overall community and functional groups of soil fungi. The links between soil multifunctionality and fungal communities were also explored.We found that long-term crop rotation increased soil multifunctionality index and that of carbon cycle. Crop rotation shifted soil fungal community composition, and reduced the proportion of putative pathotrophs. The overall fungal community was almost equally explained by soil and plant variables, while fungal functional groups (i.e., saprotrophs and pathotrophs) were more affected by soil variables. The indicator taxa in the non-legume-winter wheat rotation were distinctly different from those in the legume-based winter wheat rotation soils, indicating that the non-legume-winter wheat rotation selects different fungal taxa from the legume-based winter wheat rotation. Moreover, the changes in community composition of soil fungi, putative saprotrophs and pathotrophs were related to soil multifunctionality and that of carbon and nitrogen cycles.Our results highlight that long-term crop rotations shape the soil fungal communities; the changes in soil fungi and fungal functional groups have potential to improve soil multifunctionality in the crop rotation systems in drylands.Conclusions: Crop rotation plays an important role in changing soil microbial communities, which is critical to maintaining soil multifunctionality. However, limited data exist on the long term impact of crop rotations on soil multifunctionality and its link with soil fungal community in drylands.In a dryland field experiment with 30-year legume- and non-legume-based winter wheat rotations and winter wheat-fallow system, we investigated the soil multifunctionality (via cycling and pools of soil carbon and nitrogen) and the overall community and functional groups of soil fungi. The links between soil multifunctionality and fungal communities were also explored.We found that long-term crop rotation increased soil multifunctionality index and that of carbon cycle. Crop rotation shifted soil fungal community composition, and reduced the proportion of putative pathotrophs. The overall fungal community was almost equally explained by soil and plant variables, while fungal functional groups (i.e., saprotrophs and pathotrophs) were more affected by soil variables. The indicator taxa in the non-legume-winter wheat rotation were distinctly different from those in the legume-based winter wheat rotation soils, indicating that the non-legume-winter wheat rotation selects different fungal taxa from the legume-based winter wheat rotation. Moreover, the changes in community composition of soil fungi, putative saprotrophs and pathotrophs were related to soil multifunctionality and that of carbon and nitrogen cycles.Our results highlight that long-term crop rotations shape the soil fungal communities; the changes in soil fungi and fungal functional groups have potential to improve soil multifunctionality in the crop rotation systems in drylands. [ABSTRACT FROM AUTHOR]