Effects of drought on non-structural carbohydrates and C,N,and P stoichiometric characteristics of Pinus yunnanensis seedlings

To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,light and moderate and severe drought treatments[(80±5),(65±5),(50±5),and(35±5)%of field water-holding capacity].Non-structural carbohydrates,carbon(C),nitrogen(N),and phosphorus(P)concentrations were measured in each plant component.The results show that:(1)With increasing drought,non-structural carbohydrates gradually increased in leaves,stems,and coarse roots,while gradually decreased in fine roots;(2)C concentrations of all were relatively stable under different stress levels.Phosphorous utilization of each component increased under light and moderate drought conditions,while N and P utilization efficiency of each plant component decreased under severe drought.Growth was mainly restricted by N,first decreasing and then increasing with increased drought;(3)There was a correlation between the levels of non-structural carbohydrates and C,N,and P in each component.Changes in N concentration affected the interconversion between soluble sugar and starch,which play a regulatory role in the fluctuation of the concentration of non-structural carbohydrates;and,(4)Plasticity analysis showed that P.yunnanensis seedlings responded to drought mainly by altering starch concentration,the ratio of soluble sugar to starch in leaves and stems,and further by alter-ing N and P utilization efficiencies.Overall,these results suggest that the physiological activities of all organs of P.yunnanensis seedlings are restricted under drought and that trade-offs exist between different physiological indicators and organs.Our findings are helpful in understanding non-structural carbohydrate and nutrient adaptation mechanisms under drought in P.yunnanensis seedlings.

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

Comparative study of the stoichiometric characteristics of karst and non-karst forests in Guizhou, China

Carbon (C), nitrogen (N), and phosphorous (P) levels and their stoichiometry in plant components (leaves, branch trunks, roots) of trees in a karst forest and non-karst forest are compared. The results show that the C contents, C:N and C:P ratios of dominant species in the karst forest were lower than those in the non-karst forest, but the N and P and the N:P ratio were higher;C:N:P ratios in plant organs of trees in the karst forest were in the order of trunks>roots>branches>leaves. However, C:N:P ratio in the non-karst forest trees were trunks>branches>roots>leaves. Moreover, ratio of C:N:P in trunks was highest and lowest in leaves in both forests. In non-karst forest trees, N:P was in the order of leaves> roots>branches>trunks. There were no significant differences in the ratio of N:P in different plant components of trees in the karst forest. However, in karst and non-karst forest trees, the ratio of N:P in leaves was highest;positive correlations between N and P contents, and N and N:P ratios were observed in both karst and non-karst forests (p<0.001). Negative correlations between P and N:P ratios (p<0.05) were observed in karst forest trees, while positive correlations were observed in non-karst forest trees.

STOICHIOMETRIC AND OFF STOICHIOMETRIC ALLOYING IN Ti 5Si 3 BY Nb OR Cr ADDITION

Titanium silicide Ti 5Si 3 whose melting temperature is 2 130 ℃ bears the potential for very high temperature application. Results on Nb or Cr addition to this compound with emphasis on its alloying behaviour were reported. Previous theoretical calculation shows that substitution of Ti by Nb or Cr atoms in Ti 5Si 3 crystal will enhance the bonding between atoms. By experiment, two means of alloying were considered: stoichiometric and off stoichiometric alloying. Stoichiometric alloying in Ti 5Si 3 results in compounds consisting of single Ti 5Si 3 phase while off stoichiometric alloying yields hypereutectic microstructure with Ti 5Si 3 being the primary phase. The Ti 5Si 3 phase in both cases dissolves certain amount of Nb or Cr alloying element and its composition agrees with the stoichiometric composition of (Ti,Nb) 5Si 3 or (Ti,Cr) 5Si 3. The moduli of the stoichiometric alloys increase with alloying element addition, indicating an enhancement in Ti 5Si 3 crystal.

The two photorefractive centres in iron doped nearly stoichiometric lithium niobate crystals

This paper investigates the photorefractive properties of iron doped lithium niobate with different [Li]/[Nb] ratios The experimental results show two photorefractive centres for iron doped near-stoichiometric lithium niobate crystal Besides Fe^2＋ and Fe^3＋ ions, small polarons and bipolarons are considered as another photoactive centre.

A new equivalent method to obtain the stoichiometric fuel-air cloud from the inhomogeneous cloud based on FLACS-dispersion

The fuel-air cloud resulting from an accidental discharge event is normally irregular in shape and varying in concentration. Performance of dispersion simulations using the computational fluid dynamics （CFD）-based tool FLACS can get an uneven and irregular cloud. For the performance of gas explosion study with FLACS, the equivalent stoichiometric fuel-air cloud concept is widely applied to get a representative distribution of explosion loads. The Q9 cloud model that is employed in FLACS is an equivalent fuel-air cloud representation, in which the laminar burning velocity with first order SL and volume expansion ratio are taken into consideration. However, during an explosion in congested areas, the main part of the combustion involves turbulent flame propagation. Hence, to give a more reasonable equivalent fuel-air size, the turbulent burning velocity must be taken into consideration. The paper presents a new equivalent cloud method using the turbulent burning velocity, which is described as a function of SL, deduced from the TNO multi- energy method.

C,N,and P Ecological Stoichiometric Characteristics of Two Dominant Mosses in Baotianman Nature Reserve

In order to investigate ecological adaptation mechanism of bryophyte,two dominant mosses Thuidium cymbifolium and Mnium immarginatum in Baotianman Nature Reserve were measured the content of C,N,P and their ratio in bryophyte and soil,and analyzed the relationships of plant and soil ecological stoichiometric characteristics along altitudinal gradients.Results indicate that the content of C,N and P in green tissues of T.cymbifolium and M.immarginatum in Baotianman Nature Reserve was 46.81%-49.09%,0.21%-0.25%,and0.02%-0.08%.Among the different altitudinal gradients,C,N and P displayed significant differences: the significantly different content of C and N were showed in T.cymbifolium,and the content of N and P differed significantly in M.immarginatum.However,only N declined obviously as increasing altitude.In soil,the C,N,N/P and C/P showed an increasing trend with increasing elevation,while the P and C/N along altitudinal gradients exhibited no unified trend.With the increasing in the content C,N of soil,the content C and N of T.cymbifolium raised,while the content C and N of M.immarginatum declined.With the rise in P element of soil,N/P showed different trends between two bryophyte species,the N/P in T.cymbifolium significantly decreased,while N/P in M.immarginatum significantly increased.In addition,mean value of leaf N/P was 8.51,ranking 14-16.These results suggested that the growth of the bryophyte plants in Baotianman Nature Reserve were restricted by N element,and different utilization strategies in soil P element in different bryophyte plants led to differences in ecological stoichiometric characteristics.

Stoichiometric flexibility regulates the co-metabolism effect during organic carbon mineralization in eutrophic lacustrine sediments

Several studies have suggested the pivotal roles of eutrophic lakes in carbon(C)cycling at regional and global scales.However,how the co-metabolism effect on lake sediment organic carbon(OC)mineralization changes in response to integrated inputs of labile OC and nutrients is poorly understood.This knowledge gap hinders our ability to predict the carbon sequestration potential in eutrophic lakes.Therefore,a 45-day microcosm experiment was conducted to examine the dominant mechanisms that underpin the co-metabolism response to the inputs of labile C and nutrients in lacustrine sediments.Results indicate that the labile C addition caused a rapid increase in the positive co-metabolism effect during the initial stage of incubation,and the co-metabolism effect was positively correlated with the C input level.The positive co-metabolism effect was consistently higher under high C input,which was 152%higher than that under low C input.The higherβ-glucosidase activity after nutrient addition,which,in turn,promoted the OC mineralization in sediments.In addition different impacts of nutrients on the co-metabolism effect under different C inputs were observed.Compared with the low nutrient treatments,the largest co-metabolism effect under high C with high nutrient treatment was observed by the end of the incubation.In the high C treatment,the intensity of the co-metabolism effect(CE)under high nitrogen treatment was 1.88 times higher than that under low nitrogen condition.However,in the low C treatment,the amount of nitrogen had limited impact on co-metabolism effect.Our study thus proved that the microorganisms obviously regulate sediment OC turnover via stoichiometric flexibility to maintain a balance between resources and microbial requirements,which is meaningful for evaluating the OC budget and lake eutrophication management in lacustrine sediments.

Structure of Sn Doped AB_5 Non-Stoichiometric Hydrogen-Absorbing Alloys-Ⅰ

Five non stoichiometric alloys, i.e., LaNi 5.15 , La(NiSn) 5.14 , La(NiSnCo) 5.12 , La(NiSnMn) 5.12 , and La(NiSnCoMnAl) 5.10 were studied. It is shown that the second minor phase does not exist in the major phase through the X ray diffraction analysis. By the measurements of the crystal lattice constant, the volume of crystal lattice decreases with the increasing of the amount of atom B in AB 5. It is more obvious when the element nickel in B is partially subsituted by other elements. For non stoichiometric alloys, the lattice volume greatly increases when Ni is partially substituted by Sn. The lattice constant is also effected by the addition of Mn, Co, and Al. By means of electrochemical measurements, the plateau pressure of hydrogen absorption/desorption is measured with the results that Sn, Co, Mn and Al decrease the plateau pressure.

EFFECTS OF STOICHIOMETRIC RATIO ON STRUCTURE AND ELECTRODE PERFORMANCE OF HYDROGEN STORAGE ALLOYS

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Stoichiometric NbTiAl_3 (γ1 Phase) Alloy in Ti-Al-Nb Ternary System

The microstructure and phase constitution in stoichiometric NbTiAl3 (γ1 phase) alloy treated at 1000℃ were examined by metallography and X-ray diffraction. The alloy microstructure is mainly γ1 phase containing η second phase [(Ti,Nb)Al3] less than 1%. DTA analysis shows no phase transformation from room temperature to 1200℃. In the diffusion couple of NbTiAl3 with 7-TiAl compound, clear phase boundary and composition jump exist between γ1 and γ phase.These results further confirm the existence of γ1 single phase at 1000℃ in Ti-Al-Nb ternary system.

Stoichiometric deduction of activated sludge process for organic carbon and nitrogen removal

The activated sludge process （ASP） is the most generally applied biological wastewater treatment method. The ASP for the removal of organic carbon and nitrogen can be looked as the combination of eight processes. In order to set up an ASP model, the stoichiometric coefficients should be deduced so that the stoichiometric matrix can be presented. The important assumptions and simplifications behind the model for ASP are enumerated. Using the matrix, mass balance equation and consistent units, the stoichiometric coefficients in the eight processes are exclusively deduced one by one.

Hydrogen Diffusivity in Single Crystal Stoichiometric NiAl

The hydrogen diffusion behavior of single crystal stoichiometric NiAl was investigated. The results show that the hydrogen diffusivity and permeabilty of single crystal stoichiometric NiAl obey Arrhenius relationship in the experimental temperature range. The activation energy of hydrogen diffusion in single crystal stoichiometric NiAl is about 45 kJ/mol.

Soil microbial respiration is regulated by stoichiometric imbalances: Evidence from a humidity gradient case

Humidity not only affects soil microbial respiration(SMR) directly, but, indirectly by regulating the availability of soil water and nutrients. However,the patterns of direct and indirect effects of humidity on SMR over large precipitation gradients remain unclear, limiting our understanding of the effects of precipitation changes on soil C cycle. Here, we investigated the relationships among humidity, soil nutrients, and SMR by identifying stoichiometric imbalances, microbial elemental homeostasis, and microbial C use efficiency along a precipitation gradient at a continental scale. The relationship between SMR and humidity index(HI) corresponded to a Richard’s curve with an inflection point threshold value of approximately 0.7. Soil microbial respiration increased with increasing humidity in drier areas(HI < 0.7), but tended to balance above this threshold. Increasing humidity exacerbated C:P and N:P imbalances across the selected gradient. Severe N and P limitations in soil microbial communities were observed in drier areas, while soil microbes suffered from aggravated P limitation as the humidity increased in wetter areas(HI > 0.7). Soil microbial communities regulated their enzyme production to maintain a strong stoichiometric homeostasis in drier areas;enzyme production, microbial biomass, and threshold elemental ratios were non-homeostatic under P limitation in wetter areas, which further contributed to the increase in SMR. Our results identified a moisture constraint on SMR in drier areas and highlighted the importance of nutrient(especially for P) limitations induced by humidity in regulating SMR in wetter areas. Understanding the modulation of SMR via soil enzyme activity may improve the prediction of soil C budget under future global climate change.

Stoichiometric Imbalance-promoted Step-growth Polymerization Based on Self-accelerating Three-component Reaction

Aself-accelerating three-component reaction was developed using the secondary amines,CS_(2),and sym-dibenzo-1,5-cyclooctadiene-3,7-diyne(DIBOD)as reactants.In this three-component reaction,the secondary amine reacts with CS_(2) to form dithiocarbamate anion,which subsequently in-situ reacts with DIBOD behaving a self-accelerating reaction property.Specifically,the reaction of dithiocarbamate anion with the first alkyne of DIBOD activates the unreacted alkyne,which reacts with dithiocarbamate anion much faster than the original alkyne of DIBOD.Using the self-accelerating three-component reaction as polymerization reaction,a stoichiometric imbalance-promoted step-growth polymerization method was developed using the difunctional secondary amines,CS_(2),and DIBOD as monomer groups.This novel three-component polymerization can quickly produce high molecular weight dithiocarbamate-containing polymers under mild conditions using a slight molar excess of DIBOD to difunctional secondary amine monomer.Containing sulfur elements in the backbones,the resultant polymers hold high refractivity and may find potential applications in optical and optoelectronic fields.

Interactive effects of warming and eutrophication on zooplankton could reverse the stoichiometric mismatch with phytoplankton

The core ecosystem functioning(e.g.trophic transfer efficiency)is at risk of being disrupted by the growing mismatch between nutrient content of primary producers and nutrient demand of grazing consumers.Ecological stoichiometry provides a conceptual framework that explains this trophic interaction using C,N and P elemental composition across trophic levels.In light of ongoing climate change and eutrophication,previous studies have raised concerns regarding the growing stoichiometric mismatch between phytoplankton and zooplankton,given the stoichiometric plasticity of phytoplankton.However,there is currently little conclusive evidence on the stoichiometric mismatch from a dual perspective of phytoplankton and zooplankton.To address this,we conducted a mesocosm experiment to investigate the separate and combined effects of climate warming(a constant increase of t3.5C plus heat waves)and eutrophication(nutrient addition)on stoichiometric mismatch between phytoplankton and zooplankton by examining stoichiometric changes in both communities.We observed a growing trend in stoichiometric mismatches when warming or nutrient addition acted individually,which was mediated by the increase in nutrient demand(N,P elements)of zooplankton growth.However,when these stressors acted jointly,the mismatches were reversed.This could be because climate warming and eutrophication combined would lead to changes in species composition,which accordingly reshaped the stoichiometric composition at the community level.These results illustrate the need of stoichiometric mismatches for understanding the implication of global change on trophic interactions and ecosystem functioning,requiring consideration not only of cross-trophic levels but also of compositional changes within communities.

A STOICHIOMETRIC DISPLACEMENT MODEL FOR RETENTION OF SOLUTE IN LIQUID CHROMATOGRAPHY WITH MULTI-COMPONENT SYSTEM

Considering all the kinds of interactions between solute and solvent, solute and stationary phase, solvent and stationary phase molecules as well as the competitional adsorption among various kinds of solvent molecules on the stationary phase, we present a stoichiometric displacement model of solute retention with four sets of parameters in liquid chromatography. This model was tested with data from both literature and experiments done by ourselves. These results show that this model may fit the experimental data for a liquid chromatography system with various kinds of mobile phases consisting of a complete range of multi-components and with different types of stationary phases.

A STOICHIOMETRIC DISPLACEMENT MODEL OF SOLUTE ADSORPTION IN LIQUID-SOLID SYSTEM

Based on five thermodynamic equilibria involving solutes, solvents and adsorbents, a stoichiometric displacement adsorption model adaptable to various adsorption systems consisting of different types of solutes, solvents and adsorbents has been presented. The kernel of this model is that as the solute molecules are adsorbed by the adsorbent, a stoichiometric number of the solvent molecules is necessarily released. The model was tested with originally published data from an extensive literature. The linear parameter values from the model have been used for quantitatively explaining the phenomenon of the liquid-solid adsorption. Having compared with Langmuir model in many respects, it is found that this model is better.

Optical waveguides in LiNbO_3 and stoichiometric LiNbO_3 crystals by proton exchange

The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength of 633 and 1539 nm, re-spectively. The mode optical near-field outputs from proton-exchanged LiNbO3 and SLN waveguides at 633 nm were presented. The mode field from stoichiometric LiNbO3 (SLN) waveguide is lighter and more uniform than that from LiNbO3 waveguide, which means the quality of the waveguide in SLN crystal is better than that of the LiNbO3 waveguide. For proton-exchanged LiNbO3 waveguides, the evo-lution of the refractive index profile with annealing was presented. The disorder profiles of Nb atoms in proton-exchanged LiNbO3 waveguides were obtained by Rutherford backscattering/channeling technique. It is shown that the longer the exchange time, the larger the displacement of Nb atoms.

Low-temperature growth of stoichiometric aluminum nitride films prepared by magnetic-filtered cathodic arc ion plating

A1N films were prepared on Si（100） and quartz glass substrates with high deposition rate of 30 nm-min-I at the temperature of below 85 ℃ by the magnetic-filtered cathodic arc ion plating （FCAIP） method. The as-deposited A1N films show very smooth surface and almost no macrodroplets. The films are in amorphous state, and the formation of A1N is confirmed by Nls and A12p X-ray photoelectron spectroscopy （XPS）. The XPS depth profile analysis shows that oxygen is mainly absorbed on the A1N surface. The A1N film has A1 and N concentrations close to the stoichiometric ratio with a small amount of A1203. The prepared A1N films are highly transparent over the wave- length range of 210-990 nm. The optical transmission spectrum reveals the bandgap of 6.1 eV. The present technique provides a good approach to prepare large-scale A1N films with controlled structure and good optical properties at low temperature.