Divergent responses of cropland soil organic carbon to warming across the Sichuan Basin of China.

Cropland soils are considered to have the potential to sequester carbon (C). Warming can increase soil organic C (SOC) by enhancing primary production, but it can also cause carbon release from soils. However, the role of warming in governing cropland SOC dynamics over broad geographic scales remains poorly understood. Using over 4000 soil samples collected in the 1980s and 2010s across the Sichuan Basin of China, this study assessed the warming-induced cropland SOC change and the correlations with precipitation, cropland type and soil type. Results showed mean SOC content increased from 11.10 to 13.85 g C kg-1. Larger SOC increments were observed under drier conditions (precipitation < 1050 mm, dryland and paddy-dryland rotation cropland), which were 1.67-2.23 times higher than under wetter conditions (precipitation > 1050 mm and paddy fields). Despite the significant associations of SOC increment with crop productivity, precipitation, fertilization, cropland type and soil type, warming also acted as one of major contributors to cropland SOC change. The SOC increment changed parabolically with the rise in temperature increase rate under relatively drier conditions, while temperature increase had no impact on cropland SOC increment under wetter conditions. Meanwhile, the patterns of the parabolical relationship varied with soil types in drylands, where the threshold of temperature increase rate, the point at which the SOC increment switched from increasing to decreasing with warming, was lower for clayey soils (Ali-Perudic Argosols) than for sandy soils (Purpli-Udic Cambosols). These results illustrate divergent responses of cropland SOC to warming under different environments, which were contingent on water conditions and soil types. Our findings emphasize the importance of formulating appropriate field water management for sustainable C sequestration and the necessity of incorporating environment-specific mechanisms in Earth system models for better understanding of the soil C-climate feedback in complex environments.

Rumen Microbial Metabolic Responses of Dairy Cows to the Honeycomb Flavonoids Supplement Under Heat-Stress Conditions.

Flavonoids played critical roles in stabilizing microbial homoeostasis when animals suffered exoteric stresses. However, whether flavonoids attenuated heat stress of dairy cows is still not clear. Therefore, in the present article, flavonoids extracted from honeycomb were supplemented to investigate the production, digestibility, and rumen microbial metabolism responses of cows under heat stress conditions. A total of 600 multiparous dairy herds were randomly allotted into the control treatment (CON), the heat stress (HS) treatment, and the honeycomb flavonoids supplement under heat stress conditions (HF) treatment for a 30-day-long trial. Each treatment contains 4 replicates, with 50 cows in each replicate. Production performances including dry matter intake (DMI), milk production, and milk quality were measured on the basis of replicate. Furthermore, two cows of each replicate were selected for the measurement of the nutrient digestibility, the ruminal fermentable parameters including ruminal pH, volatile fatty acids, and ammonia-N, and the rumen microbial communities and metabolism. Results showed that HF effectively increased DMI, milk yield, milk fat, and ruminal acetate content (p < 0.05) compared with HS. Likewise, digestibility of NDF was promoted after HF supplement compared with HS. Furthermore, relative abundances of rumen microbial diversities especially Succiniclasticum, Pseudobutyrivibrio, Acetitomaculum, Streptococcus, and Succinivibrio, which mainly participated in energy metabolism, significantly improved after HF supplement. Metabolomic investigation showed that HF supplement significantly upregulated relative content of lipometabolic-related metabolites such as phosphatidylglycerol, phosphatidylinositol, phosphatidylserine, and phosphatidylethanolamine, while it downregulated biogenic amines. In summary, HF supplement helps proliferate microbial abundances, which further promoted fiber digestibility and energy provision, and ultimately enhances the production performances of dairy cows under heat stress conditions.

Efficient reclamation phosphate by alginate-g-BMOF using poly(N-isopropyl acrylamide-co-acrylamide) as coating for temperature-responsive slow-release P-fertilizer.

Poly(N-isopropyl acrylamide) and its derived copolymer, as a temperature-responsive material, are widely used in the field of anticancer drug carrier. And it also plays an important role as carrier in slow-release fertilizer in recent years. In this paper, a smart poly(N-isopropyl acrylamide-co-acrylamide)-coated Alg-BMOF (PABMOF) was fabricated in ionic liquids microemulsion ([Bmim]PF6/TX-100/water) as nano-reactor. The structure and morphology of PABMOF were characterized by FT-IR, XRD, XPS, SEM, TG and BET. The resultant PABMOF was used as a adsorbent for H2PO4- adsorption. The adsorption kinetics, isotherms and mechanism of H2PO4- onto the resultant PABMOF were studied. The adsorption kinetic data was well suitable for pseudo-second-order kinetic model, and adsorption isotherm results demonstrated that the equilibrium data was fitted for Freundlich model. The water-holding and water-retention capacity of soil with TRSRFs addition of 2 wt% were74.3% and 52.13% at 30th day, respectively. Moreover, the release behavior of TRSRFs in water show that the cumulative release rate (Cr%) were 81.4% at 45 °C and 97.6% at 25 °C within 172 h, which displayed the excellent temperature-responsive property. The effect of TRSRFs on the growth of Chinese cabbage was investigated, which was indexed with the germination rate, plant height and root length of the crop.

Soil acidification of the soil profile across Chengdu Plain of China from the 1980s to 2010s.

Soil acidification is a major environmental issue associated with intensive agricultural land use. Rapid urbanization has inevitably caused great changes in agricultural land use around urban areas. However, the effects of agricultural land-use change and soil parent material on the pH dynamics of the whole soil profile remain poorly understood. Based on a paired soil resampling campaign in the 1980s and 2010s, this study evaluated the effects of agricultural land-use change and parent materials on the pH dynamics of the soil profile across the Chengdu Plain of China. The results showed that soil pH significantly decreased by 1.20, 0.72, 0.66 and 0.68 units at the 0-20, 20-40, 40-60 and 60-100 cm soil depths, respectively. Conversions of traditional rice-wheat/rapeseed rotations to rice-vegetable rotations and afforested land significantly increased the magnitude of pH decline at the 0-60 cm soil depth. Soils formed from Q4 grey-brown alluvium and Q4 grey alluvium, which had a lower soil bulk density (BD) and higher sand content, showed a much higher magnitude of pH decline than soils formed from Q3 (Quaternary Pleistocene) old alluvium, and significant acidification of deep soils only occurred in soils formed from Q4 (Quaternary Holocene) grey-brown alluvium and Q4 grey alluvium. These results suggested that agricultural land-use change aggravated acidification in the soil profile and the soil acidification degrees were parent material-dependent; in particular, significant acidification of deep soils was more inclined to occur in soils with lower soil BD and higher sand content due to their effects on the downward movement of acids and the penetration resistance of plant roots. More attention should be given to minimizing or preventing acidification of both topsoil and deep soils aggravated by agricultural land-use change across urban agricultural areas.

Optimization of beam transformation system for laser-diode bars.

An optimized beam transformation system (BTS) is proposed to improve the beam quality of laser-diode bars. Through this optimized design, the deterioration of beam quality after the BTS can be significantly reduced. Both the simulation and experimental results demonstrate that the optimized system enables the beam quality of a mini-bar (9 emitters) approximately equal to 5.0 mm × 3.6 mrad in the fast-axis and slow-axis. After beam shaping by the optimized BTS, the laser-diode beam can be coupled into a 100 µm core, 0.15 numerical aperture (NA) fiber with an output power of over 100 W and an electric-optical efficiency of 46.8%.

High brightness laser-diode device emitting 160 watts from a 100 µm/NA 0.22 fiber.

A practical method of achieving a high-brightness and high-power fiber-coupled laser-diode device is demonstrated both by experiment and ZEMAX software simulation, which is obtained by a beam transformation system, free-space beam combining, and polarization beam combining based on a mini-bar laser-diode chip. Using this method, fiber-coupled laser-diode module output power from the multimode fiber with 100 µm core diameter and 0.22 numerical aperture (NA) could reach 174 W, with equalizing brightness of 14.2 MW/(cm2·sr). By this method, much wider applications of fiber-coupled laser-diodes are anticipated.

High-brightness spectral beam combining of diode laser array stack in an external cavity.

We demonstrate the spectral beam combining of a diode laser stack, which contains three 970nm Mini-Bars along the fast-axis direction, in an external cavity. At the pump current of 60 A, the output power of 127 W, the spectral bandwidth of 12 nm and the Electro-optical conversion efficiency of 48.35% are achieved. The measured beam qualities after the spectral beam combining are M(2) ≈10.2 along the slow axis and M(2) ≈11.5 along the fast axis. Under a maximum injection current of 75A, the laser output power of more than 159W is achieved. The beam quality deteriorated slightly with the rising of the current from 60A to 75A, but it is enough to be coupled into a 50µm core / 0.22NA fiber.

Beam shaping design for compact and high-brightness fiber-coupled laser-diode system.

Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. A compact and high-brightness fiber-coupled system has been designed based on a significant beam shaping method. The laser-diode stack consists of eight mini-bars and is effectively coupled into a standard 100 µm core diameter and NA=0.22 fiber. The simulative result indicates that the module will have an output power over 440 W. Using this technique, compactness and high-brightness production of a fiber-coupled laser-diode module is possible.

High brightness beam shaping and fiber coupling of laser-diode bars.

The strong beam quality mismatch in the fast and slow axes of laser-diode bars requires a significant beam shaping method to reach the parameters needed for fiber coupling. An effective solution to this problem is proposed that is based on a right-angle prism array and a distributed cylinder-lens stack. Coupling 12 mini-bars into a standard 100 µm core diameter and 0.15 numerical aperture fiber is achieved, and the output power can reach 400 W. Using this technique, production of compact and high brightness fiber-coupled laser-diode modules is possible.

[Differences in phosphorus utilization efficiency among wheat cultivars].

A pot experiment was conducted to study the differences in the biomass, phosphorus concentration, phosphorus use efficiency for dry matter, and phosphorus use efficiency for grain yield among different wheat cultivars under low phosphorus supply, aimed to screen the wheat varieties with high phosphorus use efficiency. For the test cultivars, their biomass per plant at tillering, jointing, flowering, and maturing stages was 0.46-1.09, 0.85-2.10, 3.00-7.00, and 3.85-12.88 g, and their phosphorus concentration was 2.21-4.26, 2.38-4.42, 2.44-4.96, and 1.30-5.09 mg x g(-1), respectively. From tillering to maturing stages, the phosphorus accumulation in plant and the phosphorus use efficiency for dry matter displayed a decreasing effect on the biomass formation. Significant differences were observed in the phosphorus use efficiency for dry matter (tillering stage CV = 16.3%, jointing stage CV = 15.0%, and flowering stage CV = 13.3%) and in the phosphorus use efficiency for grain yield (maturing stage CV = 20.5%) among the cultivars. The cultivars CD1158-7 and Sheng A3 Yi 034 had higher phosphorus use efficiency for dry matter and phosphorus use efficiency for grain yield, while the Yu 02321 was in adverse. The phosphorus concentration in the cultivars with high phosphorus use efficiency was significantly lower than that in the cultivars with low phosphorus use efficiency, and the grain yield of CD1158-7 and Sheng A3 Yi 03-4 was 0.98 times and 0.78 times higher than that of Yu 02321.

Visible light assisted photocatalytic degradation of methyl orange using Ag/N-TiO2 photocatalysts.

For the sake of efficient utilization of sunlight, Ag nanoparticles loaded N-doped TiO2 photocatalysts (Ag/N-TiO2) were successfully fabricated via a two-step method to make the best use of the respective advantages of noble metal loading and nonmetal doping. Ag/N-TiO2 was characterized using XRD, XPS and UV-Vis DRS. Compared to TiO2, the dramatic enhancement of the visible-light-induced photocatalytic degradation efficiency of Ag/N-TiO2 obtained for the degradation of methyl orange should be attributed to the synergistic effect of N-doping and Ag-loading, including the good visible light absorption and the effective electron-hole separations. This demonstrates Ag/N-TiO2 is a promising photocatalytic material for organic pollutant degradation under visible light irradiation.

Realizing visible-light-induced self-cleaning property of cotton through coating N-TiO2 film and loading AgI particles.

The visible-light-induced self-cleaning property of cotton has been realized by coating N-TiO(2) film and loading AgI particles simultaneously. The physical properties were characterized by means of XRD, SEM, TEM, XPS, and DRS techniques. The visible light photocatalytic activities of the materials were evaluated using the degradation of methyl orange. In comparison with TiO(2)-cotton, the dramatic enhancement in the visible light photocatalytic performance of the AgI-N-TiO(2)-cotton could be attributed to the synergistic effect of AgI and N-TiO(2), including generation of visible light photocatalytic activity and the effective electron-hole separations at the interfaces of the two semiconductors. The photocatalytic activity of the AgI-N-TiO(2)-cotton was fully maintained upon several numbers of photodegradation cycles. In addition, according to the XRD patterns of the AgI-N-TiO(2)-cotton before and after reaction, AgI was stable in the composites under visible light irradiation. Moreover, a possible mechanism for the excellent and stable photocatalytic activity of AgI-N-TiO(2)-cotton under visible light irradiation was also proposed.

[Effects of seed soaking with biogas slurry on seed germination and seedling growth of Tagetes erecta].

OBJECTIVE: The experiment was conducted to study the effect of soaking seeds with biogas slurry on seed germination and growth of Tagetes erecta so that we can provide theory base for cultivation management of T. ercta. METHOD: In order to find the best combine of biogas slurry concentration (25%, 50%, 75%, 100%) and soaking time (2, 3, 4, 5 h), completely randomized design was selected, germination percentage, seedling height, root length, root activity, content of chlorophyll (a, b) and MDA were analyzed and principle component analysis was adopted. RESULT: Both soaking for 5 h in 25% biogas slurry and soaking for 4 h in 50% biogas slurry had the highest germination percentage (81.3%). Soaking for 5 h in 50% biogas slurry had the longest root, and soaking for 4 h in 50% biogas slurry had the highest root activity. They were significant higher than other 19 treatments. Soaking for 5 h in 50% biogas slurry had the highest content of chlorophyll a, chlorophyll b, chlorophyll (a + b) and ratio of chlorophyll a/ chlorophyll b. It was significant higher in these index, except b, than other 19 treatment. Soaking for 5 h in 25% biogas slurry had the lowest MDA content (0.0280 micromol x L(-1)), then was Soaking for 4 h in 50% biogas slurry (0.0286 micromol x L(-1) in MDA content). CONCLUSION: Appropriate biogas slurry concentration combined with seed soaking time can improve the germination and growth of T. erecta. As a whole, soaking for 5 h in 50% biogas slurry had the best effects on germination and growth in seedling stage for T. erecta.

Synthesis of visible-light responsive graphene oxide/TiO(2) composites with p/n heterojunction.

Graphene oxide/TiO(2) composites were prepared by using TiCl(3) and graphene oxide as reactants. The concentration of graphene oxide in starting solution played an important role in photoelectronic and photocatalytic performance of graphene oxide/TiO(2) composites. Either a p-type or n-type semiconductor was formed by graphene oxide in graphene oxide/TiO(2) composites. These semiconductors could be excited by visible light with wavelengths longer than 510 nm and acted as sensitizer in graphene oxide/TiO(2) composites. Visible-light driven photocatalytic performance of graphene oxide/TiO(2) composites in degradation of methyl orange was also studied. Crystalline quality and chemical states of carbon elements from graphene oxide in graphene oxide/TiO(2) composites depended on the concentration of graphene oxide in the starting solution. This study shows a possible way to fabricate graphene oxide/semiconductor composites with different properties by using a tunable semiconductor conductivity type of graphene oxide.

Template-free sol-gel preparation and characterization of free-standing visible light responsive C,N-modified porous monolithic TiO2.

Visible light responsive C,N-modified porous monolithic titania (MT(f)) has been successfully synthesized. The template-free sol-gel synthesis method accompanied by phase separation and in situ C,N-modification has been used. The molar ratio of water to tetrabutyl titanate (f) in starting solution plays an important role in the porous structure and photoactivity of MT(f). Scanning electron microscopy (SEM) analysis and N(2) adsorption-desorption analysis show that MT(f) possess mesoporous structure as well as macroporous structure. MT(22) has been further characterized by using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra (DRS). The results show that both nitrogen and carbon elements exist in MT(22) and result in the visible light photocatalytic activity of MT(22). The observed reaction rate of decolorization of methyl orange is 0.0026 min(-1).

[Research advances in plant lead tolerance and detoxification mechanism].

To have an overall understanding about the physiological mechanisms of plants in their lead (Pb) absorption, transportation, accumulation, and detoxification is the prerequisite of the phytoremediation of Pb-polluted soil. This paper reviewed the research advances in the mechanisms of plant Pb-adaptation and recovery, including the functions of cell wall and vacuole in Pb-inactivation and sequestration in plant cells, the effects of plant root exudates on Pb bioavailability, the roles of antioxidative enzymes dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX), and of antioxidants phytochelatins (PCs) and glutathione in Pb detoxification, and the expression and function of metallothionein and Pb-specific genes. The further researches on the plant's Pb-tolerance and detoxification mechanisms as well as the technologies for phytoremediation of Pb-contaminated environments were prospected.

In-situ synthesis of photocatalytic CuAl2O4-Cu hybrid nanorod arrays.

Copper aluminate-copper hybrid nanorod arrays possessing superior visible-light driven photocatalytic properties were synthesized inside porous anodic aluminum oxide (AAO) under mild electrochemical conditions.

Preparation of photocatalytic anatase nanowire films by in situ oxidation of titanium plate.

Photocatalytic anatase TiO2 nanowire thin films have been prepared by in situ oxidation of Ti plate in a mixture solution of concentrated H(2)O(2) and NaOH, followed by proton exchange and calcination. The morphologies and properties of the titanate and titania films have been investigated by means of field emission scanning electron microscopy, energy-dispersive x-ray spectrometry, high resolution transmission electron microscopy, x-ray diffraction and Raman spectrometry. The mechanism of formation of the porous microstructure has been discussed; it is the result of the balance between dissolution and precipitation. And sodium ions in the solution are needed to combine with titanate species for the nanowire formation. The anatase TiO2 nanowire thin films exhibited enhanced photocatalytic activity and stability in phenol degradation. The combination effects of the porous morphology and nanowire characteristics are favorable for improved photocatalytic performance. This novel nanowire film is promising for practical aqueous purification.

Removing dye rhodamine B from aqueous medium via wet peroxidation with V-MCM-41 and H2O2.

A new heterogeneous Fenton-like system, consisting of V-MCM-41 catalyst and hydrogen peroxide, was proved to be effective in removing recalcitrant dye Rhodamine B (RhB) in aqueous solutions. V-MCM-41 was prepared following a direct hydrothermal procedure with tetraethyl silicate and ammonium metavanadate as precursor. The mesoporous structure has been characterized by XRD, and the specific surface area was determined as x m(2) g(-1) according to BET method. The catalytic reaction can proceed in a relatively wide pH range from acidic to alkaline. And the visible light irradiation cannot promote the reaction process. In addition, the mechanism implication for V-MCM-41 as a Fenton-like catalyst has been discussed.