Low soil temperature reducing the yield of drip irrigated rice in arid area by influencing anther development and pollination

Drip irrigation can produce high rice yields with significant water savings;therefore,it is widely used in arid area water-scarce northern China.However,high-frequency irrigation of drip irrigation with low temperature well water leads to low root zone temperature and significantly reduce the rice yield compared to normal temperature water irrigated rice,for example,reservoir water.The main purpose of this paper is to investigate the effects of low soil temperature on the yield reduction of drip irrigated rice in the spike differentiation stage.The experiment set the soil temperatures at 18℃,24℃and 30℃under two irrigation methods(flood and drip irrigation),respectively.The results showed that,at the 30℃soil temperature,drip irrigation increased total root length by 53%but reduced root water conductivity by 9%compared with flood irrigation.Drip irrigation also increased leaf abscisic acid and proline concentrations by 13%and 5%,respectively.These results indicated that drip irrigated rice was under mild water stress.In the 18℃soil temperature,drip irrigation reduced hydraulic conductivity by 58%,leaf water potential by 40%and leaf net photosynthesis by 25%compared with flood irrigation.The starch concentration in male gametes was also 30%less in the drip irrigation treatment than in the flood irrigation treatment at soil temperature 18℃.Therefore,the main reason for the yield reduction of drip irrigated rice was that the low temperature aggravates the physiological drought of rice and leads to the decrease of starch content in male gametes and low pollination fertilization rate.Low temperature aggravates physiological water deficit in drip irrigated rice and leads to lower starch content in male gametes and low pollination fertilization rate,which is the main reason for the reduced yield of drip irrigated rice.Overall,the results indicated that the low soil temperatures aggravated the water stress that rice was under in the drip irrigated environment,causing declines both in the starch content of male gametes and in pollination rate.Low temperature will ultimately affect the rice yield under drip irrigation.

Density functional calculations of efficient H_2 separation from impurity gases(H_2,N_2,H_2O,CO,Cl_2, and CH_4)via bilayer g-C_3N_4 membrane

Membrane technology has been used for H_2 purification. In this paper, the systematic density functional simulations are conducted to study the separation of H_2 from the impurity gases(H_2, N_2, H_2 O, CO, Cl_2, and CH_4) by the bilayer porous graphitic carbon nitride(g-C_3 N_4) membrane. Theoretically, the bilayer g-C3 N4 membrane with a diameter of about3.25 A? should be a perfect candidate for H_2 purification from these mixed gases, which is verified by the high selectivity(S) for H_2 over other kinds of gases(3.43 × 1028 for H_2/N2; 1.40 × 1028 for H_262/H_2 O; 1.60 × 10 for H_2/CO; 4.30 × 10^(14) for H_2/Cl_2; 2.50 × 10^(55) for H_2/CH_4), and the permeance(P) of H_2(13 mol/m^2·s·Pa) across the bilayer g-C_3 N_4 membrane at 300 K, which should be of great potential in energy and environmental research. Our studies highlight a new approach towards the final goal of high P and high S molecular-sieving membranes used in simple structural engineering.

Effects of iron and humic acid on competition between Microcystis aeruginosa and Scenedesmus obliquus revealed by HPLC analysis of pigments

Iron is a vital micronutrient for growth of bloom-forming Microcystis aeruginosa and competition with other algae,and its availability is affected by humic acid.The effect of iron and humic acid on growth and competition between M.aeruginosa and Scenedesmus obliquus was assessed.The results showed the growth of M.aeruginosa and S.obliquus in mono-cultures was inhibited by humic acid at low iron concentrations(0.01 mg/L);the maximum inhibition ratios were 67.84%and 38.31%,respectively.The inhibition of humic acid on the two species was significantly alleviated when iron concentrations were 1.00 mg/L,with the maximum inhibition rate reduced to 5.82%for M.aeruginosa and to 23.06%for S.obliquus.S.obliquus was the dominant species in mixed cultures,and the mutual inhibition between M.aeruginosa and S.obliquus at low iron concentration was greater than that at high iron concentration.The inhibition of S.obliquus on M.aeruginosa was reduced at low iron concentrations;it increased at high iron concentrations,as concentrations of humic acid rose.

Conducting polymer-functionalized mesoporous metal-organic frameworks for high-performance Li-S battery

It was known that mesoporous metal-organic frameworks(MOFs)with hierarchical pores and unsaturated metal sites can effectively inhibit the shuttle effect of lithium polysulfides in lithium-sulfur battery,however,the unsatisfactory structural stability and electrical conductivity limit the application of mesoporous MOFs(MMOFs)in Li-S batteries.Aiming at sensible solutions,the conductive polyaniline(PANI)was incorporated into the MMOF to enhance the discharge capacity and the cycling stability of proposed Li-S batteries,as the stability and the conductivity of the MMOF cathode was improved simultaneously.The activated MMOF-PANI provides physical and chemical adsorption of polysulfides against their shuttle effect.Moreover,the introduction of PANI into the channels of MMOF effectively improves the conductivity of MMOF,thus improving the electrochemical performance of the MMOF-PANI-based batteries.Benefiting from these synergetic effects,the S@MMOF-PANI cathode delivers improved electrochemical performance including excellent rate performance and cycling stability.The battery shows an initial capacity of 777.7 mAh·g^(−1)at 2.0 C and a low decay rate of 0.06%per cycle in 1,000 cycles and approximately a repeatable rate performance.

Dynamic nano-Ag colloids cytotoxicity to and accumulation by Escherichia coli:Effects of Fe^3+,ionic strength and humic acid

Released Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials,and thus,the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag+ ratios.Our recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays,and shifts to both Ag particles and released Ag^+ in 48 hr bioassays.Herein,as a continued study,the cytotoxicity and accumulation of 50 and 100 nm Ag colloids in Escherichia coli were determined dynamically.The cytotoxicity and mechanisms of nanoAg colloids are dynamic throughout exposure and are derived from both Ag ions and particles.Ag accumulation by E.coli is derived mainly from extracellular Ag particles during the initial 12 hr of exposure,and thereafter mainly from intracellular Ag ions.Fe^3+ accelerates the oxidative dissolution of nano-Ag colloids,which results In decreasing amounts of Ag particles and particle-related toxicity.Na^+ stabilizes nano-Ag colloids,thereby decreasing the bioavailability of Ag particles and particle-related toxicity.Humic acid(HA) binds Ag^+ to form Ag^+-HA,decreasing ion-related toxicity and binding to the E.coli surface,decreasing particle-related toxicity.HA in complex conditions showed a stronger relative contribution to toxicity and accumulation than Na^+ or Fe^3+.The results highlighted the cytotoxicity and mechanism of nano-Ag colloids are dynamic and affected by environmental factors,and therefore exposure duration and water chemistry should be seriously considered in environmental and health risk assessments.

Promotion of photocatalytic steam reforming of methane over Ag^0/Ag^+-SrTiO3

Methane(CH4)is not only used as a fuel but also as a promising clean energy source for hydrogen generation.The steam reforming of CH4(SRM)using photocatalysts can realize the production of syngas(CO+H2)with low energy consumption.In this work,Ag0/Ag+-loaded SrTi03 nanocomposites were successfully prepared through a photodeposition method.When the loading amount of Ag is 0.5 mol%,the atom ratio of Ag+to Ag0 was found to be 51:49.In this case,a synergistic effect of Ago and Ag+was observed,in which Ago was proposed to improve the adsorption of H2 O to produce hydroxyl radicals and enhance the utilization of light energy as well as the separation of charge carriers.Meanwhile,Ag0 was regarded as the reduction reaction site with the function of an electron trapping agent.In addition,Ag+adsorbed the CH4 molecules and acted as the oxidation reaction sites in the process of photocatalytic SRM to further promote electron-hole separation.As a result,0.5 mol%Ag-SrTi03 exhibited enhancement of photocatalytic activity for SRM with the highest CO production rate of 4.3μmol g-1 h-1,which is ca.5 times higher than that of pure SrTi03.This work provides a facile route to fabricate nanocomposite with cocatalyst featuring different functions in promoting photocatalytic activity for SRM.