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1. chinaXiv:202102.00066 [pdf]

Aggregate binding agents improve soil aggregate stability in Robinia pseudoacacia forests along a climatic gradient on the Loess Plateau, China

JING Hang; MENG Min; WANG Guoliang; LIU Guobin
Subjects: Geosciences >> Geography

The distribution of binding agents (i.e., soil organic carbon (SOC) and glomalin-related soil protein (GRSP)) in soil aggregates was influenced by many factors, such as plant characteristics and soil properties. However, how these factors affect binding agents and soil aggregate stability along a climatic gradient remained unclear. We selected the Robinia pseudoacacia L. forests from semi-arid to semi-humid of the Loess Plateau, China to analyze the plant biomass, soil physical-chemical properties, SOC and GRSP distribution in different sized soil aggregates. We found that from semi-arid to semi-humid forests: (1) the proportion of macro-aggregates (>0.250 mm) significantly increased (P<0.05), whereas those of micro-aggregates (0.250–0.053 mm) and fine materials (<0.053 mm) decreased and soil aggregate stability was increased; (2) the contents of SOC and GRSP in macro-aggregates and micro-aggregates significantly increased, and those in fine materials decreased; (3) the contribution of SOC to soil aggregate stability was greater than those of total GRSP and easily extractable GRSP; (4) soil properties had greater influence on binding agents than plant biomass; and (5) soil aggregate stability was enhanced by increasing the contents of SOC and GRSP in macro-aggregates and soil property was the important part during this process. Climate change from semi-arid to semi-humid forests is important factor for soil structure formation because of its positive effect on soil aggregates.

submitted time 2021-02-10 From cooperative journals:《Journal of Arid Land》 Hits765Downloads419 Comment 0

2. chinaXiv:202011.00135 [pdf]

Rapid loss of leguminous species in the semi-arid grasslands of northern China under climate change and mowing from 1982 to 2011

XU,Bo; HUGJILTU,Minggagud; BAOYIN,Taogetao; ZHONG,Yankai; BAO,Qinghai; ZHOU,Yanlin; LIU,Zhiying
Subjects: Geosciences >> Geography

Effects of mowing on the composition and diversity of grasslands varied with climate change (e.g., precipitation and temperature). However, the interactive effects of long-term mowing and climate change on the diversity and stability of leguminous and non-leguminous species in the semi-arid grasslands are largely unknown. Here, we used in situ monitoring data from 1982 to 2011 to examine the effects of continuous mowing and climate change on the plant biomass and diversity of leguminous and non-leguminous species, and soil total nitrogen in the typical semi-arid grasslands of northern China. Results showed that the biomass and diversity of leguminous species significantly decreased with the increasing in the biomass and diversity of non-leguminous species during the 30-a period. Variations in biomass were mainly affected by the long-term mowing, while variations in diversity were mainly explained by the climate change. Moreover, the normalized change rates of diversity in leguminous species were significantly higher than those in non-leguminous species. Mowing and temperature together contributed to the diversity changes of leguminous species, with mowing accounting for 50.0% and temperature 28.0%. Temporal stability of leguminous species was substantially lower than that of non-leguminous species. Consequently, soil total nitrogen decreased in the 2000s compared with the 1980s. These findings demonstrated that leguminous species were more sensitive to the long-term mowing and climate change than non-leguminous species in the semi-arid grasslands. Thus, reseeding appropriate leguminous plants when mowing in the semi-arid grasslands may be a better strategy to improve nitrogen levels of grassland ecosystems and maintain ecosystem biodiversity.

submitted time 2020-11-25 From cooperative journals:《Journal of Arid Land》 Hits2646Downloads521 Comment 0

3. chinaXiv:202010.00017 [pdf]

Cultivation effects on soil texture and fertility in an arid desert region of northwestern China

HE,Mingzhu; JI,Xibin; BU,Dongsheng; ZHI,Jinhu
Subjects: Geosciences >> History of Geosciences

In arid desert regions of northwestern China, reclamation and subsequent irrigated cultivation have become effective ways to prevent desertification, expand arable croplands, and develop sustainable agricultural production. Improvement in soil texture and fertility is crucial to high soil quality and stable crop yield. However, knowledge on the long-term effects of the conversion of desert lands into arable croplands is very limited. To address this problem, we conducted this study in an arid desert region of northwestern China to understand the changes in soil physical-chemical properties after 0, 2, 5, 10, 17, and 24 years of cultivation. Our results showed that silt and clay contents at the 17-year-old sites increased 17.5 and 152.3 folds, respectively, compared with that at the 0-year-old sites. The soil aggregate size fraction and its stability exhibited an exponential growth trend with increasing cultivation ages, but no significant change was found for the proportion of soil macroaggregates (>5.00 mm) during the 17 years of cultivation. The soil organic carbon (SOC) content at the 24-year-old sites was 6.86 g/kg and increased 8.8 folds compared with that at the 0-year-old sites. The total (or available) nitrogen, phosphorus, and potassium contents showed significant increasing trends and reached higher values after 17 (or 24) years of cultivation. Changes in soil physical-chemical properties successively experienced slow, rapid, and stable development stages, but some key properties (such as soil aggregate stability and SOC) were still too low to meet the sustainable agricultural production. The results of this long-term study indicated that reasonable agricultural management, such as expanding no-tillage land area, returning straw to the fields, applying organic fertilizer, reducing chemical fertilizer application, and carrying out soil testing for formula fertilization, is urgently needed in arid desert regions.

submitted time 2020-10-20 From cooperative journals:《Journal of Arid Land》 Hits2556Downloads701 Comment 0

4. chinaXiv:202004.00005 [pdf]

金融科技中支持区块链生态系统的一般共识博弈框架

袁先智
Subjects: Mathematics >> Applied Mathematics
Subjects: Information Science and Systems Science >> Other Disciplines of Information Science and Systems Science

本文的目的是建立区块链生态系统中采矿池博弈共识均衡的一般框架,特别是在区块链生态系统中,通过使用一个新的概念“共识博弈(Consensus Game)”,解释与挖掘差距(Gap Games)博弈行为相关的共识均衡存在的意义上的稳定性,这里,区块链生态系统主要是指应用2008年中本聪(Nakamoto)所提出的“工作证明”(Proof of Work) 这一关键共识,将区块链工作的费用、报酬机制和采矿权三类不同因素考虑在内的经济活动。 为了做到这一点,我们首先概述了采矿池游戏共识均衡的一般存在性是如何表述的,然后通过区块链共识框架下共识均衡的存在性来解释比特币缺口博弈 (Gap博弈) 稳定性,然后利用博弈论中矿工的利润函数作为收益,建立了一般矿业缺口博弈一致均衡的一般存在性结果。作为应用,建立了缺口博弈 (Gap博弈)一致均衡的一般存在性结果,这不仅有助于我们在区块链生态系统的一般框架下断言缺口博弈 (Gap博弈) 的一般稳定性的存在性,但也让我们能够说明在研究采矿池博弈时的一些不同现象,这些现象可能是由于采矿者的(Gap博弈)行为与嵌入比特币经济学的情景造成的。 我们对区块链生态系统挖掘缺口博弈稳定性的解释研究表明,共识均衡的概念可能对共识经济学基础理论的发展起到重要作用

submitted time 2020-03-31 Hits20925Downloads1811 Comment 0

5. chinaXiv:201803.01544 [pdf]

Ni3+ doped cobalt-??nickel layered double hydroxides as high performance electrode material for supercapacitors

Hongmei Sun; Yixing Ye; Zhenfei Tian; Shouliang Wu; Jun Liu
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology

Co-Ni layered double hydroxides (LDHs), as promising supercapacitor electrode materials with high specific capacity, have suffered poor rate property and cycle stability. By doping and topochemical oxidation of Ni ions is considered as efficivent rout to overcome these drawbacks. In this work, Ni3+ doped cobalt-nickel layered double hydroxides (Co-Ni-LDHs) were synthesized by pluse laser ablation of Ni taget in CoCl2 aqeous solution. The existence of Ni3+ ions doped in Co-Ni-LDHs decline the conductive resistance, and increase the mobility of surface charge and transfer rate of electrolyte. As a results, the Ni3+ doped Co-Ni-LDHs display a maximum specific capacitance of 2275 F/g and 1450 F/g at the current density of 1 A/g and 20 A/g, respectivly, indicating a high rate specific capacitance. Moreover, the capacitance retention is to be 80% after 1800 cycles at the current density of 6 A/g, manifesting good cycling stability of Ni3+ doped Co-Ni-LDHs.

submitted time 2018-03-30 Hits2895Downloads1431 Comment 0

6. chinaXiv:201803.01545 [pdf]

Site-specifically Immobilize Pt Nanocrystals on NiFe Layered Double Hydroxide: Old Catalysts with Enhanced Stability Through strong Fe3+-O(H)-Pt Interfacial Contact

Yechuang Han; Pengfei Li; Jun Liu; Shouliang Wu ; Yixing Ye; Zhenfei Tian; Changhao Liang
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology

Agglomeration-triggered deactivation of supported platinum electrocatalysts markedly hinders their application in methanol oxidation reaction (MOR). In this study, graphene-supported nickel–iron layered double hydroxide (NiFe–LDH/rGO), in which Fe3+ was introduced to replace Ni2+ partially in the Ni(OH)2 lattice to provide stronger metal–support bonding sites, was utilized to immobilize Pt nanoparticles (NPs). Given the optimized metal–support interfacial contact (Fe3+–O(H)–Pt) between Pt NPs and NiFe–LDH/rGO nanosheets for Pt/NiFe–LDH/rGO electrocatalysts, the Pt/NiFe–LDH/rGO electrocatalysts displayed dramatically enhanced durability than that of Pt/Ni(OH)2/rGO counterpart as well as commercial Pt/C, and 86.5% of its initial catalytic activity can be maintained even after 1200 cycles of cyclic voltammetry (CV) tests during MOR. First-principle calculations toward the resultant M–O(H)–Pt (M = Fe3+, Ni2+) interfacial structure further corroborates that the NiFe–LDH nanosheets can provide stronger bonding sites (via the Fe3+–O(H)–Pt bonds) to immobilize Pt NPs than those of Ni(OH)2 nanosheets (via the Ni2+–O(H)–Pt bonds).

submitted time 2018-03-30 Hits2874Downloads1383 Comment 0

7. chinaXiv:201801.00699 [pdf]

酶法糖基化合成一种新型补骨脂定葡萄糖苷

李静; 李楠; 赵玉茹; 戴轶群; 霍强; 马涛; 李红梅; 吴成柱
Subjects: Medicine, Pharmacy >> Preclinical Medicine

Objective To modify the structure of psoralidin using in vitro enzymatic glycosylation to improve its water solubilityand stability. Methods A new psoralidin glucoside (1) was obtained by enzymatic glycosylation using a UDP-glycosyltransferase. The chemical structure of compound 1 was elucidated by HR-ESI-MS and nuclear magnetic resonance(NMR) analysis. The high-performance liquid chromatography (HPLC) peaks were integrated and sample solution concentrations were calculated. MTT assay was used to detect the cytotoxicity of the compounds against 3 cancer cell lines in vitro. Results Based on the spectroscopic data, the new psoralidin glucoside was identified as psoralidin-6',7-di-O glucopyranoside (1), whose water solubility was 32.6-fold higher than that of the substrate. Analyses of pH and temperature stability demonstrated that compound 1 was more stable than psoralidin at pH 8.8 and at high temperatures. Only psoralidin exhibited a moderate cytotoxicity against 3 human cancer cell lines. Conclusion In vitro enzymatic glycosylation is a powerful approach for structural modification and improving water solubility and stability of compounds.

submitted time 2018-01-25 From cooperative journals:《南方医科大学学报》 Hits1740Downloads984 Comment 0

8. chinaXiv:201711.00023 [pdf]

Numerical Investigation of Effect of Inlet Swirl and Total-pressure Distortion on Performance and Stability of an Axial Transonic Compressor

Naseri, A; Boroomand, M; Sammak, S
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Experimental results on the thermal characteristics of air-water spray impingement cooling of hot metallic surface are presented and discussed in this paper. The controlling input parameters investigated were the combined air and water pressures, plate thickness, water flow rate, nozzle height from the target surface and initial temperature of the hot surface. The effects of these input parameters on the important thermal characteristics such as heat transfer rate, heat transfer coefficient and wetting front movement were measured and examined. Hot flat plate samples of mild steel with dimension 120 mm in length, 120 mm breadth and thickness of 4 mm, 6 mm, and 8 mm respectively were tested. The air assisted water spray was found to be an effective cooling media and method to achieve very high heat transfer rate from the surface. Higher heat transfer rate and heat transfer coefficients were obtained for the lesser i.e, 4 mm thick plates. Increase in the nozzle height reduced the heat transfer efficiency of spray cooling. At an inlet water pressure of 4 bar and air pressure of 3 bar, maximum cooling rates 670 degrees C/s and average cooling rate of 305.23 degrees C/s were achieved for a temperature of 850 degrees C of the steel plate.

submitted time 2017-11-02 From cooperative journals:《热科学学报》 Hits2145Downloads575 Comment 0

9. chinaXiv:201711.00040 [pdf]

Numerical Analysis of Flow Instability in the Water Wall of a Supercritical CFB Boiler with Annular Furnace

Xie, B. B., ; Yang, D.,; Xie, H. Y., ; Nie, X. ; Liu, W. Y.
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Supersonic cavity flows are characterized by compression and expansion waves, shear layer, and oscillations inside the cavity. For decades, investigations into cavity flows have been conducted, mostly with flows at zero pressure gradient entering the cavity in straight walls. Since cavity flows on curved walls exert centrifugal force, the features of these flows are likely to differ from those of straight wall flows. The aim of the present work is to study the flow physics of a cavity that is cut out on a curved wall. Steady and unsteady numerical simulations were carried out for supersonic flow through curved channels over the cavity with L/H = 1. A straight channel flow was also analyzed which serves as the base model. The velocity gradient along the width of the channel was observed to increase with increasing the channel curvature for both concave and convex channels. The pressure on the cavity floor increases with the increase in channel curvature for concave channels and decreases for convex channels. Moreover, unsteady flow characteristics are more dependent on channel curvature under supersonic free stream conditions.

submitted time 2017-11-02 From cooperative journals:《热科学学报》 Hits958Downloads525 Comment 0

10. chinaXiv:201708.00258 [pdf]

Systematic Study of Survival Probability of Excited Superheavy Nuclei

Cheng-Jun XIA; Bao-Xi SUN; En-Guang ZHAO; Shan-Gui ZHOU
Subjects: Physics >> Nuclear Physics

The stability of excited superheavy nuclei (SHN) with 100 Z 134 against neutron emission and fission is investigated by using a statistical model. In particular, a systematic study of the survival probability against fission in the 1n-channel of these SHN is made. In present calculations the neutron separation energies and shell correction energies are consistently taken from the calculated results of the finite range droplet model which predicts an island of stability of SHN around Z = 115 and N = 179. It turns out that this island of stability persists for excited SHN in the sense that the calculated survival probabilities in the 1n-channel of excited SHN at the optimal excitation energy are maximized around Z = 115 and N = 179. This indicates that the survival probability in the 1n-channel is mainly determined by the nuclear shell effects.

submitted time 2017-08-22 Hits1002Downloads559 Comment 0

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