Grazing period management affects the accumulation of plant functional groups, and soil nutrient pools and regulates stoichiometry in the desert steppe of Northwest China.

To understand how nutrient cycling and sequestration are influenced by different grazing periods, the C:N:P stoichiometry features of the plant-soil interface in the desert steppe were measured and evaluated. The 5-year seasonal grazing experiment employed four grazing period treatments: traditional time of grazing (TG), early termination of grazing (EG), delayed start of grazing (DG), and delayed start and early termination of grazing (DEG). Additionally, fenced off desert steppe served as the control. The grazing periods each had a differing impact on the C:N:P stoichiometry in both plant functional group and soil depth comparisons. Compared to the EG, DG, and DEG treatments, the TG treatment had a more significant impact on the C, N, and P pools of grass, as well as the C:P and N:P ratios of forbs, but had a reduced effect on the C:P and N:P ratios of legumes. In contrast to plants, the DG treatment exhibited greater advantages in increasing C pools within the 0-40 cm soil layer. Furthermore, in the 10-20 cm soil layer, the C:P and N:P ratios under the EG treatment were significantly higher, ranging from 8.88% to 53.41% and 72.34%-121.79%, respectively, compared to the other treatments (TG, DG, and DGE). The primary drivers of the C, N, and P pools during different grazing periods were above-ground biomass (AGB) and litter biomass (LB). Both lowering the plant C:P and N:P ratios and considerably raising the plant P pool during different grazing periods greatly weakened the P limitation of the desert steppe environment. It is predicted that delayed start grazing might be a management strategy for long-term ecosystem sustainability, as it regulates above-ground nutrient allocation and has a positive effect on soil C and N pools.

Large-area large-grain CsPbCl3perovskite films by confined re-growth for violet photodetectors.

CsPbCl3perovskite is an attractive semiconductor material with characteristics such as a wide bandgap, high chemical stability, and excellent optoelectronic properties, which broaden its application prospects for ultraviolet (UV) and violet photodetectors (PDs). However, large-area CsPbCl3films with high coverage, large grains, and controllable thickness are still difficult to prepare by using the solution method due to the extremely low solubility of their precursors in conventional solvents. Herein, a water-assisted confined re-growth method is developed, and a CsPbCl3microcrystalline film with an area of 3 cm × 3 cm is grown, the thickness of which is controllable within a range of several microns. The as-prepared thin film exhibits a flat and smooth surface, large grains, and enhanced photoluminescence. Furthermore, the fabricated violet PDs based on the prepared CsPbCl3film show a high responsivity of 2.17 A W-1, external quantum efficiency of 664%, on/off ratio of 2.58 × 103, and good stability. This study provides a prospective solution for the growth of large-area, large-grain, and surface-smooth CsPbCl3films for high-performance UV and violet PDs.

Extending grazing time during the warm season can reduce P limitation and increase the N cycling rate in arid desert steppes.

Ecological stoichiometry serves as a valuable tool for comprehending biogeochemical cycles within grassland ecosystems. The impact of grazing time on the concentration and stoichiometric characteristics of carbon (C), nitrogen (N), and phosphorus (P) in desert steppe ecosystems remains ambiguous. This research was carried out in a desert grassland utilizing a completely randomized experimental design. Four distinct grazing time treatments were implemented: fenced grassland (FG, control), delay to start and early to end grazing grassland (DEG), delay to start grazing grassland (DG), and traditional grazing grassland (TG). The patterns of C, N, and P concentrations and their stoichiometry in various components of the ecosystem, as well as their driving factors under different grazing times were examined. The results showed that grazing time positively influenced C and N concentrations in leaves, while negatively affecting N concentrations in roots. TG had a significant positive effect on soil P concentrations but a negative effect on soil C:P and N:P ratios. Plant C:N, C:P, and N: P ratios were mainly influenced by N and P. The soil C:N ratio was primarily influenced by soil N, the soil C:P ratio was affected by both soil C and P, and the soil N:P ratio was influenced by both soil N and P. The growth of plants in desert steppes is mainly limited by P; however, as grazing time increased, P limitation gradually decreased and the N cycling rate increased. C-N, C-P, and N-P in various plant organs and soils demonstrated significant anisotropic growth relationships at different grazing times. Soil organic carbon, pH, and soil total phosphorus were the main driving factors that affected changes in ecological C:N:P stoichiometry. These results will help improve grassland management and anticipate the response of grassland systems to external disturbances with greater accuracy.

[Effect of folate on the proliferation of human cervical cancer cell and relationship with HPV16].

OBJECTIVE: To study the effect of different concentration of folate in vitro on the proliferation and apoptosis of C33A cell with HPV negative and CaSki cell with HPV16 positive, and intreaction of folate and HPV16. METHODS: C33A and Caski cells were intervened by different concentration of folate (0.1, 1.0, 10, 50, 100, 500, 1,000 and 2,000 microg/ml). The morphological changes of cells were examined by reverse discrepancy microscope. MTT and Flow Cytometry (FCM) were employed to measure the proliferation, inhibition ratio, cell cycle and apoptosis of cells. RT-PCR was used to detect the expression of HPV16 E2/E6 oncogene. RESULTS: The effects of folate on the C33A and CaSki cell growth suppression were increased gradually with the concentration of folate increasing and cultured duration prolonging, the inhibition ratio was increased (C33A: r = 0.948, P = 0.010; CaSki: r = 0.895, P = 0.006). Adding folate could induce cell apoptosis (C33A: r = 0.989, P < 0.001; CaSki: r =0.994, P < 0.001), and there was a linear relationship, but there was no significant difference on the proliferation and apoptosis of C33A and CaSki cells effected. In addition, concentration of folate did not affect the expression of HPV16 E2/E6. CONCLUSION: Different concentration of folate inhibited cervical cancer cell proliferation and enhanced cell apoptosis, but the results do not support an interaction between folate and HPV16 in cervical cancer cell.

Did Wheat Breeding Simultaneously Alter Grain Concentrations of Macro- and Micro-Nutrient Over the Past 80 Years of Cultivar Releasing in China?

Biofortification of wheat with mineral through crop breeding is a sustainable and cost-effective approach to address human mineral malnutrition. A better understanding of the trends of grain concentrations of mineral nutrients in wheat over the breeding period may help to assess the breeding progress to date. A 2-year field experiment using 138 Chinese wheat landraces and 154 cultivars was conducted. Grain concentrations of micronutrients (Cu and Mn) and macronutrients (N, P, and K) were measured and corrected for a yield level to elucidate the trends of these mineral nutrients over the 80 years of cultivar releasing and identify genetic variation for these mineral nutrients in cultivars and landraces. Large genetic variation exists for grain mineral nutrients concentrations among tested genotypes, indicating that selection for enhancing mineral nutrient concentrations in wheat is possible. Landraces showed a slightly wide genetic variation of grain Cu concentration and a much narrow variation of Mn concentration when compared to modern cultivars. Grain concentrations of Cu and Mn decreased slightly with increasing grain yield with a weak correlation, while N, P, and K concentrations declined obviously with increasing yield with a strong correlation, revealing that increased grain yield had a strong negative effect on grain concentration of macronutrients, but a relative weak negative effect on micronutrients concentrations. When considering the impact of the variation in yield on mineral concentrations, grain concentrations of Cu, Mn, N, P, and K in wheat cultivars released from 1933 to 2017 exhibited different trends with a year of variety release. Grain Cu, N, and P concentrations showed significant decreasing trends over a breeding period, while grain Mn and K concentrations showed no clear trend, suggesting wheat breeding in China over the past 80 years has decreased grain concentrations of Cu, N, and P, and did not alter Mn and K concentrations. Finally, a total of 14 outstanding accessions with high grain mineral nutrients concentrations/contents were identified, and these genotypes can be considered as promising donors for developing mineral-dense wheat cultivars.

[Research advances on the effects of grazing on plant functional traits in grassland]. / æ”¾ç‰§å¯¹è‰åŽŸæ¤ç‰©åŠŸèƒ½æ€§çŠ¶å½±å“ç ”ç©¶è¿›å±•.

Plant functional traits is connected with vegetation adaptability to the environment. The trade-off between plant functional traits reflects resource reintegration and acquisition under grazing pressures. We summarized the differences of plant functional traits under grazing disturbance, focused on the linkages between grazing disturbance and plant functional traits. We introduced that the variation of plant functional traits resulted from the coordination between plant genetic characteristics and environmental filtration, summarized the effects of grazing on nutritional and reproductive traits, and noted that plants could use survival and reproductive strategies to adapt to the grazing disturbance. We mainly focused on the effects of grazing on plant population, community and ecosystem. The expression of plant functional traits was different under grazing disturbance. Therefore, plant functional traits could be used as indicators to explain population growth and reproduction, community assembly, and ecosystem function. In order to better serve the ecological environment of grassland with plant functional traits, reasonable grazing resis-tant species could be screened according to plant functional traits. Based on life history characteristics of grassland plant population, the scientific grazing mechanism should be formulated, and the responses of plant functional traits and resource allocation to grazing disturbance should be conducted from the perspective of individual-based level in the future.

Recent advances toward environment-friendly photodetectors based on lead-free metal halide perovskites and perovskite derivatives.

Recently, metal-halide perovskites have emerged as promising materials for photodetector (PD) applications owing to their superior optoelectronic properties, such as ambipolar charge transport characteristics, high carrier mobility, and so on. In the past few years, rapid progress in lead-based perovskite PDs has been witnessed. However, the critical environmental instability and lead-toxicity seriously hinder their further applications and commercialization. Therefore, searching for environmentally stable and lead-free halide perovskites (LFHPs) to address the above hurdles is certainly a worthwhile subject. In this review, we present a comprehensive overview of currently explored LFHPs with an emphasis on their crystal structures, optoelectronic properties, synthesis and modification methods, as well as the PD applications. LFHPs are classified into four categories according to the replacement strategies of Pb2+, including AB(ii)X3, A3B(iii)2X9, A2B(i)B(iii)'X6, and newly-emerging perovskite derivatives. Then, we give a demonstration of the preliminary achievements and limitations in environment-friendly PDs based on such LFHPs and perovskite derivatives, and also discuss their applications in biological synapses, imaging, and X-ray detection. With the perspective of their properties and current challenges, we provide an outlook for future directions in this rapidly evolving field to achieve high-quality LFHPs and perovskite derivatives for a broader range of fundamental research and practical applications.

Effects of foliar application of micronutrients on concentration and bioavailability of zinc and iron in wheat landraces and cultivars.

Foliar application of micronutrient is a rapid and promising strategy to enhance the concentration and bioavailability of micronutrients in wheat grain. To explore the effects of foliar application of micronutrients on the concentration and bioavailability of zinc and iron in grain in wheat cultivars and landraces, field experiments were carried out using 65 wheat cultivars and 28 landraces to assess the effects of foliar application of zinc (iron) on phytic acid concentrations, zinc (iron) concentrations and their molar ratios. The results indicated that mean grain zinc concentration of landraces (44.83 mg kg-1) was 11.13% greater than that of cultivars (40.34 mg kg-1) on average across seasons, while grain iron concentration did not differ significantly between landraces (41.00 mg kg-1) and cultivars (39.43 mg kg-1). Foliar zinc application significantly improved the concentration and bioavailability of zinc in grains in both cultivars and landraces, while landraces had almost two-fold more increase in grain zinc and also greater improvement in zinc bioavailability compared to cultivars. While foliar iron application did not significantly affect iron concentration and bioavailability in grains in either cultivars or landraces. Our study showed that, with foliar application of zinc but not iron, wheat landraces had better performance than cultivars in terms of the increases in both concentration and bioavailability of micronutrient in grains.

Stable and Self-Powered Solar-Blind Ultraviolet Photodetectors Based on a Cs3Cu2I5/ß-Ga2O3 Heterojunction Prepared by Dual-Source Vapor Codeposition.

Self-powered solar-blind ultraviolet (UV) photodetectors have drawn worldwide attention in recent years because of their important applications in military and civilian areas. In this study, a dual-source vapor codeposition technique was employed, for the first time, to prepare a nontoxic copper halide Cs3Cu2I5, which was integrated with the ß-Ga2O3 wafer to construct a type-II heterojunction for photodetection applications. By optimizing the annealing conditions, high-quality Cs3Cu2I5 films with dense morphology, high crystallinity, and a long carrier lifetime of 1.02 µs were acquired. Because of the high material integrity of Cs3Cu2I5 films and effective interfacial carrier transfer from Cs3Cu2I5 to ß-Ga2O3, a heterojunction device demonstrates a good solar-blind UV response property and operates at zero bias. Typically, the photodetector presents a low dark current (∼1.2 pA), a high solar-blind/UVA rejection ratio (∼1.0 × 103), a relatively fast photoresponse speed (37/45 ms), and a high photo-to-dark current ratio (∼5.1 × 104) at zero bias. Moreover, even after 12-h continuous working and 2-month storage without encapsulation in ambient air, the photodetection ability of the device can almost be maintained, demonstrating outstanding air stability. Our results suggest that nontoxic Cs3Cu2I5 is able to serve as a prospective candidate for stable solar-blind UV photodetection.

Antisolvent-Processed One-Dimensional Ternary Rubidium Copper Bromine Microwires for Sensitive and Flexible Ultraviolet Photodetectors.

Recently, newly emerging halide perovskites have aroused intensive attention in photoelectric fields in virtue of their good properties, such as well-balanced carrier transport, large light absorption coefficient, tunable band gap, and low-temperature solution processing technique. Nevertheless, their future commercial development is severely hampered by lead toxicity and instability of such materials. In this work, one-dimensional Rb2CuBr3 single-crystal microwires (MWs) were prepared by antisolvent engineering, and they were further employed as absorbers to prepare sensitive ultraviolet (UV) photodetectors. The optical band gap of Rb2CuBr3 MWs is measured to be 3.83 eV, exhibiting an excellent UV absorption. The fabricated device demonstrates a remarkable UV light detection ability with a specific detectivity of 1.23 × 1011 Jones, responsivity of 113.64 mA W-1, and response speed of 69.31/87.55 ms under light illumination of 265 nm. Meanwhile, the proposed photodetector without any encapsulation shows outstanding stability and repeatability. After storing in ambient air for 2 weeks, the light detection ability remains basically unchanged. Further, a flexible photodetector was fabricated with the same structure, which demonstrates a remarkable bending endurance. These results confirm the great potential of Rb2CuBr3 for high-performance UV photodetectors, increasing the possibility for assembly of optoelectronic systems.

A solution-processed ternary copper halide thin films for air-stable and deep-ultraviolet-sensitive photodetector.

Recently, the newly emerging lead-halide perovskites have received tremendous attention in the photodetection field because of their intrinsic large light absorption and high well-balanced carrier transport characteristics. Unfortunately, the issue of instability and the existence of toxic lead cations have greatly restricted their practical applications and future commercialization. Furthermore, the previous studies on perovskite photodetectors mainly operate in visible and near-infrared light region, and there are practically no relevant reports aimed at the deep-ultraviolet (DUV) region. In this study, an air-stable and DUV-sensitive photoconductive detector was demonstrated with a solution-processed ternary copper halides Cs3Cu2I5 thin films as the light absorber. The proposed photodetector is very sensitive to wavelengths of light below 320 nm and unresponsive to the visible light. Because of the high material integrity and large surface coverage of the Cs3Cu2I5 thin films, the detector presents an outstanding photodetection performance with a photoresponsivity of ∼17.8 A W-1, specific detectivity of 1.12 × 1012 Jones, and fast response speed of 465/897 µs, superior to previously reported DUV photodetectors based on other material systems. Unlike traditional lead-halide perovskites, the lead-free Cs3Cu2I5 shows remarkable stability against heat, UV light, and environmental oxygen/moisture. Thus, the unsealed photodetector demonstrates good operation stability for 11 h of continuous running in open air. Even after 80-day storage in ambient air, its photodetection capability can nearly be maintained. The results suggest that non-toxic Cs3Cu2I5 could be a potential candidate for stable and environment friendly DUV detectors, enabling an assembly of optoelectronic systems in the future.

Strategy of All-Inorganic Cs3Cu2I5/Si-Core/Shell Nanowire Heterojunction for Stable and Ultraviolet-Enhanced Broadband Photodetectors with Imaging Capability.

In this study, for the first time, the integration of nontoxic ternary copper halide Cs3Cu2I5 with one-dimensional Si nanowires (NWs) was reported to achieve an ultraviolet (UV)-enhanced Si NW broadband photodetector. A compact and uniform coverage of Cs3Cu2I5 on the top and sidewall of Si NWs formed a core/shell heterostructure, in which Si NWs served as the growth template and the electron-transport layer, and Cs3Cu2I5 was employed as the UV photoactive material and the hole-transport layer. The as-fabricated Cs3Cu2I5/Si-core/shell NW photodetector demonstrates a multiband photodetection from the deep UV to near-infrared region, a fast response speed of 92.5/189.2 µs (265 nm), and a high photoresponsivity of 130 mA/W, nearly 600 times as much as the reference device constructed using Si NWs. More importantly, the proposed photodetector exhibits an excellent stability in air ambient. Typically, it could endure a high temperature of 60 °C for 11 h consecutive working; after storage in air ambient for two weeks, its photodetection ability can almost be retained. Additionally, high-resolution UV imaging applications were presented by employing the proposed photodetector as sensing pixels. These obtained results verify the effectiveness of the Cs3Cu2I5/Si-core/shell NW heterojunction strategy for UV-enhanced broadband photodetection, making such a device really possible for practical applications.