Current Location:home > Browse

1. chinaXiv:202112.00005 [pdf]

Effect of nitrogen and phosphorus addition on leaf nutrient concentrations and nutrient resorption efficiency of two dominant alpine grass species

LIU Yalan; LI Lei; LI Xiangyi; YUE Zewei; LIU Bo
Subjects: Geosciences >> Geography

Nitrogen (N) and phosphorus (P) are two essential nutrients that determine plant growth and many nutrient cycling processes. Increasing N and P deposition is an important driver of ecosystem changes. However, in contrast to numerous studies about the impacts of nutrient addition on forests and temperate grasslands, how plant foliar stoichiometry and nutrient resorption respond to N and P addition in alpine grasslands is poorly understood. Therefore, we conducted an N and P addition experiment (involving control, N addition, P addition, and N+P addition) in an alpine grassland on Kunlun Mountains (Xinjiang Uygur Autonomous Region, China) in 2016 and 2017 to investigate the changes in leaf nutrient concentrations (i.e., leaf N, Leaf P, and leaf N:P ratio) and nutrient resorption efficiency of Seriphidium rhodanthum and Stipa capillata, which are dominant species in this grassland. Results showed that N addition has significant effects on soil inorganic N (NO3–-N and NH4+-N) and leaf N of both species in the study periods. Compared with green leaves, leaf nutrient concentrations and nutrient resorption efficiency in senesced leaves of S. rhodanthum was more sensitive to N addition, whereas N addition influenced leaf N and leaf N:P ratio in green and senesced leaves of S. capillata. N addition did not influence N resorption efficiency of the two species. P addition and N+P addition significantly improved leaf P and had a negative effect on P resorption efficiency of the two species in the study period. These influences on plants can be explained by increasing P availability. The present results illustrated that the two species are more sensitive to P addition than N addition, which implies that P is the major limiting factor in the studied alpine grassland ecosystem. In addition, an interactive effect of N+P addition was only discernable with respect to soil availability, but did not affect plants. Therefore, exploring how nutrient characteristics and resorption response to N and P addition in the alpine grassland is important to understand nutrient use strategy of plants in terrestrial ecosystems.

submitted time 2021-11-10 Cooperative journals:《Journal of Arid Land》 Hits1003Downloads267 Comment 0

2. chinaXiv:201711.00125 [pdf]

Synthesis, Crystal Structure and Fluorescent Properties of Silver and Cadmium Complexes

WANG Qing-Wei; LIU Bo; SUI Wei
Subjects: Chemistry >> Physical Chemistry

Two new complexes [Ag(bix)]n·nNAA·nH2O (1) and [Cd(NAA)(phen)2(H2O)]2·2CH3COO-·H2O (2) (bix = 1,4-bis(imidazol-1-ylmethyl)benzene, HNAA = α-naphthylacetic acid, phen = 1,10-phenanthroline) have been successfully synthesized under hydrothermal conditions. Their structures have been determined by elemental analyses, IR spectroscopy, TG and single-crystal X-ray diffraction analysis. The intermolecular hydrogen bonding or π-π stacking interactions extend the complexes into a 3D supramolecular structure. Moreover, the luminescent properties of complex 2 have been investigated in the solid state.

submitted time 2017-11-05 Cooperative journals:《结构化学》 Hits4894Downloads2431 Comment 0

3. chinaXiv:201711.00156 [pdf]

Synthesis and Crystal Structure of a New Zinc(II) Coordination Polymer Assembled by 4-Nitrophthalic Acid and Bis(imidazol) Ligands

XING Zheng; WANG Qing-Wei; SUI Wei; LIU Bo
Subjects: Chemistry >> Physical Chemistry

A new complex [Zn(4-nph)(bib)]2n·nH2O (1) has been obtained by the reaction of metal (Zn(II)), 1,4-bis(imidazol-1-yl)-butane (bib) with 4-nitrophthalic acid (4-H2nph). The crystal structure of 1 has been determined by single-crystal X-ray diffraction analysis. Compound 1 is of triclinic system, space group P with a = 10.3251, b = 12.4503, c = 16.6497 ?, α = 88.487(3), β = 72.529(3), γ = 79.991(3)°, V = 2009.8(5) ?3 and Mr = 945.47. Complex 1 shows a three-dimensional (3D) framework. Moreover, through intermolecular hydrogen bonds, compound 1 is assembled into a supramolecular structure. The thermal stability and luminescent properties of 1 are also investigated.

submitted time 2017-11-05 Cooperative journals:《结构化学》 Hits1980Downloads1123 Comment 0

4. chinaXiv:201703.01049 [pdf]

Inverse Heat Conduction Estimation of Inner Wall Temperature Fluctuations under Turbulent Penetration

GUO Zhouchao; LU Tao; LIU Bo
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics

Turbulent penetration can occur when hot and cold fluids mix in a horizontal T-junction pipe at nuclear plants. Caused by the unstable turbulent penetration, temperature fluctuations with large amplitude and high frequency can lead to time-varying wall thermal stress and even thermal fatigue on the inner wall. Numerous cases, however, exist where inner wall temperatures cannot be measured and only outer wall temperature measurements are feasi- ble. Therefore, it is one of the popular research areas in nuclear science and engineering to estimate temperature fluctuations on the inner wall from measurements of outer wall temperatures without damaging the structure of the pipe. In this study, both the one-dimensional (1D) and the two-dimensional (2D) inverse heat conduction problem (IHCP) were solved to estimate the temperature fluctuations on the inner wall. First, numerical models of both the 1D and the 2D direct heat conduction problem (DHCP) were structured in MATLAB, based on the finite difference method with an implicit scheme. Second, both the 1D IHCP and the 2D IHCP were solved by the steepest descent method (SDM), and the DHCP results of temperatures on the outer wall were used to estimate the temperature fluctuations on the inner wall. Third, we compared the temperature fluctuations on the inner wall estimated by the 1D IHCP with those estimated by the 2D IHCP in four cases: (1) when the maximum disturbance of temperature of fluid inside the pipe was 3癈, (2) when the maximum disturbance of temperature of fluid inside the pipe was 30癈, (3) when the maximum disturbance of temperature of fluid inside the pipe was 160癈, and (4) when the fluid temperatures inside the pipe were random from 50癈 to 210癈.

submitted time 2017-03-31 Cooperative journals:《热科学学报》 Hits2498Downloads1033 Comment 0

  [1 Pages/ 4 Totals]