Value Of Gs Research Articles

Soil Characteristics in the Yetni Yahukimo River Area

Rivers have a significant role in life and economic activity in Papua. The river not only acts as a source of raw water or irrigation water but is also rich in biodiversity. Uncontrolled logging and methods of clearing land for various purposes, including agricultural use by burning, have resulted in land damage. The land investigation aims to determine the characteristics of the soil in the Yetti River, Yahukimo Regency, Papua, which is used as a basis for deciding infrastructure development. The methods used with geotechnical investigations (soil mechanics) are boring, sondir, and laboratory tests. From the laboratory test results, it is known that the soil in that location is dominated by clay soil with an average value of Gs 2.5, the water content of 27.7%, ɣm = 1.67 Mg / m3 and Sr = 74.01%.

Effect of glutathione-stabilized silver nanoparticles on expression of las I and las R of the genes in Pseudomonas aeruginosa strains

BackgroundBiofilm formation is regarded as a significant factor in the establishment of infections caused by Pseudomonas aeruginosa. P. aeruginosa is one of the most important causes of nosocomial infections. Today silver nanoparticles (Ag-NPs) are used as antimicrobials due to their well-known, chemical, biological, and physical properties. Exposure to nanoparticles could inhibit colonization of new bacteria onto the biofilm.MethodsIn the present work, the green synthesis of Ag-NPs was performed using the alcoholic extract of Eucalyptus camaldulensis. Ag-NPs and glutathione-stabilized silver nanoparticles (GSH–Ag-NPs) were characterized using X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscope (SEM), and carbon, nitrogen, and hydrogen (CNH) and Fourier transform infrared spectroscopy (FTIR) techniques were applied to investigate the structure of the modified nanoparticles. Then, the antimicrobial and antibiofilm potential of the prepared Ag-NPs and GSH–Ag-NPs against P. aeruginosa strains was evaluated using microbroth dilution method and their effects on the expression of las I and las R genes.ResultsIn this study, a total of 50 P. aeruginosa isolates were recovered from clinical samples. According to the results, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) value of Ag-NPs against P. aeruginosa was determined to be 512–256 μg/ml, respectively, while the MIC and MBC value of GS–Ag-NPs against P. aeruginosa clinical strains was determined in a range of 128–256 μg/ml and 256–512 μg/ml, respectively. The mean expression level in las R, las I genes in P. aeruginosa strains treated with ½ MIC of Ag-NPs was decreased by −5.7 and −8fold, respectively. The mean expression levels of las R, las I genes in P. aeruginosa strains treated with ½ MIC of GS–Ag-NPs were decreased by −8.7 and −10fold, respectively (P < 0.05).ConclusionsThe results of our study showed that Ag-NPs and GS–Ag-NPs are highly effective against P. aeruginosa strains. Moreover, this study also proves the promising potential of using nanoparticles as anti-biofilm formation and antibacterial agents.

Photosynthetic efficiency of hydroponically-grown tomato plants to decentralized wastewater treatment systems (DEWATS) effluents and nitrified urine concentrate (NUC) as nutrient sources

There is increasing interest and wide recognition of the potential use of human-excreta derived materials (HEDM) as fertiliser to supply essential nutrients needed for crop production. This has additional benefits as part of a reuse-oriented sustainable sanitation approach in efforts aimed at addressing sanitation challenges in many parts of the developing world. However, most work on HEDMs has focused on yield responses when compared to chemical commercial fertiliser sources using soils. Not much work has considered different systems such as hydroponic production. The physiological responses of plants to different HEDM when used in a hydroponic system is currently not well understood. This study evaluated the effect of decentralized wastewater treatment system (DEWATS) effluents and nitrified urine concentrate (NUC) as nutrient sources on hydroponically grown tomatoes. The study was conducted using 'Monica' determinate tomatoes planted in a polyethylene tunnel located at Newlands-Mashu Research Station, KwaZulu-Natal, South Africa. The experiment was laid out using a complete randomized block design and comprised of three treatments, namely, DEWATS effluent, NUC and commercial hydroponic fertilizer mix (CHFM). Each treatment was replicated three times giving nine experimental units of five plants each planted in a 5 L polyethylene pot. Data was collected on the following physiological variables: leaf area index (LAI), chlorophyll content index (CCI), stomatal conductance (gs), net CO(2) assimilation rate (A), intercellular CO(2) concentration (Ci) and the ratio of intercellular CO(2) and atmospheric CO(2) (Ci/Ca) were evaluated at vegetative stage, three weeks after transplanting. Results showed that tomato plants receiving CHFM had the highest LAI (3.00), followed by NUC (1.85) and DEWATS (1.48). CCI was significantly higher in the NUC treatments (42.58) compared to the CHFM (30.51) and DEWATS effluent (23.60). DEWATS effluent reported high values of A (22.75) followed by CHFM (22.40) and NUC by (14.56). The value of gs was higher in the DEWATS effluent (0.44) compared to the values of 0.110 and 0.021 observed for NUC and CHFM, respectively. Further, Ci was higher using DEWATS effluent compared to NUC and CHFM. The current study demonstrated that the use of HEDM such as NUC and DEWATS effluent as nutrient sources have comparable effects with commercial fertilizer mix with respect to the physiology of hydroponically grown tomatoes.

Effects of Submerged Vegetation Density on Turbulent Flow Characteristics in an Open Channel

The vegetation density λ affects turbulent flow type in the submerged vegetated river. This laboratory study investigates different types of vegetated turbulent flow, especially the flow at 0.04 &lt; λ &lt; 0.1 and λ = 1.44 by setting the experimental λ within a large range. Vertical distributions of turbulent statistics (velocity, shear stress and skewness coefficients), turbulence kinetic generation rate and turbulence spectra in different λ conditions have been presented and compared. Results indicate that for flow at 0.04 &lt; λ &lt; 0.1, the profiles of turbulent statistics manifest characteristics that are similar to those of both the bed-shear flow and the free-shear flow, and the turbulence spectral curves are characterized with some slight humps within the low-frequency range. For λ = 1.44, the turbulent statistics above the vegetation top demonstrate the characteristics of boundary-shear flow. The spectral curves fluctuate intensely within the low-frequency range, and the spectra of low-frequency eddies above vegetation top are significantly larger than the values below. The change of turbulent flow type induced by an increase of λ would increase the maximum value of turbulence kinetic generation rate GS and change the point where GS is vertically maximum upwards to the vegetation top.

High tunnel cultivation of sweet cherry (Prunus avium L.): physiological and production variables

Use of high tunnels in sweet cherry production is a popular way to reduce rain-induced fruit cracking. However, little information is available for its effects on tree physiology and fruit quality in established sweet cherry orchards. The aim of this study was to evaluate changes in the physiological and production variables of sweet cherry under high tunnels in a Mediterranean type climate in the Central Valley of Chile (35º 1’ S, 71º 32’ W). In 2017, a trial was conducted in a commercial orchard with the early and highly - productive cultivar combination of ‘Royal Dawn’ on ‘MaxMa 14’. Trees were trained as a Y-trellis, spaced at 4.5 x 2.0 m and drip irrigated with four emitters (each emitter of 4 L h-1) per tree. Two treatments of five blocks per treatment were imposed. Treatments were ‘covered’ = trees under multi-bay Haygrove® high tunnels and ‘open’ = trees under open field conditions (control). The average value of gs increased during fruit development but the values under cover were generally 30% higher than in the open. Full bloom occurred 4 days earlier under cover and fruit was harvested 8 days earlier than that in the open and yields were similar (15 kg tree-1). Trees under high tunnels received 20% less amount of water than uncovered trees. There were no differences in fruit quality from different canopy layers. Significantly less cracking losses (3%) were observed in covered trees compared with open (19%). No differences in the ratio of leaf area to fruit number (193 cm2 fruit-1) were found between covered and open trees but fruit from covered trees were larger, less sweet and softer in firmness than that from trees in the open. These altered fruit quality attributes should be improved in relation to the target market and the associated requirements for transport and storage. Results indicate that the use of high tunnels for ‘Royal Dawn’ on ‘MaxMa 14’ sweet cherry production, in a Mediterranean type climate, reduces susceptibility to rain-induced cracking, advances the time of harvest and increases fruit size.

Stomatal heterogeneity in responses to humidity and temperature: Testing a mechanistic model.

The role of stomatal heterogeneity in the response of stomatal conductance (gs ) to the mole fraction difference in water vapour between the inside of the leaf and the ambient air (Δw) was determined using thermography and gas exchange for 3 species. The value of Δw for the leaf was varied in 2 different ways: first by varying air humidity while holding leaf temperature constant and second by varying leaf temperature while holding air humidity constant. Stomatal heterogeneity was explored by examining the response of gs in small areas of the leaf (as determined by thermography) and comparing them to each other and to the average value of gs (as determined by gas exchange). These analyses show that despite substantial heterogeneity in gs values, the response of gs to Δw was qualitatively similar in all areas of the leaf, and all responses of gs to Δw were well predicted by a recently proposed, vapour-phase mechanism for stomatal responses to temperature and humidity. Remarkably, the 2 model parameters, Θ and Z, that depend on leaf anatomy were constant for a given species, and only the maximum conductance varied in different regions of the leaf.

A Newton-based shooting method to find synaptic threshold in active cables

The integration of synaptic inputs in a neuron can be nonlinear not just at the axon, but also locally in the dendrites if they are imbued with active voltage-gated ion channels. For example, CA1 pyramidal neurons have high densities of sodium and potassium and currents in their dendrites, and these densities can vary substantially in the arbor [1,2]. Such nonlinearities can lead to compartmentalized responses to inputs [3], with branches acting as individual nonlinear units in which dendritic spikes occur. A cell can thus function as a multi-layered network with the soma as final output. This motivates determining when a given set of synaptic inputs is large enough to generate a local dendritic spike, or, alternatively, determining the synaptic conductance value(s) at threshold for producing a spike. Above- and below-threshold conditions are known to be separated by the threshold or critical surface [4]. Here it is shown that the synaptic conductance leading to a threshold solution can be found by modifying Newton methods developed to find steady-state solutions in fluid mechanics [5]. Consider a general form of the cable equation, ∂u∂t=L(x)u+N(u,x)+gsGs(t,x)(urev-u) Here u represents the voltage and any gating variables. The first term on the right models the diffusive part of the cable equation, and the next term the nonlinearities from any active voltage-gated ion channels. The last term represents synaptic conductances at points in the dendritic tree with overall strength gs . An unstable threshold solution and accompanying synaptic strength can be found using 1) a preconditioned version of the steady-state cable equation combined with constraints requiring the difference between a shooting solution from rest, u(T,x;gs), and the critical surface to be perpendicular to the single unstable eigenvector associated with the critical surface. The overall procedure finds the value of gs leading to a solution that asymptotes to the critical surface as t goes to ∞. Example results from the method are shown in Figure ​Figure1.1. These are for the Fitzhugh-Nagumo model without recovery in a y-branched cable morphology where the daughter branches have half the diameter of the main dendrite. One observes the expected drop of threshold conductance as the synapse moves from the main to daughter branch, but this transition is not monotonic as for a passive cable because of the nonlinear active conductance in the model. Discovering phenomena such as this would be quite laborious without employing a Newton-based method. Figure 1 Threshold Fitzhugh-Nagumo voltage profile in a branched cable for synapse position just past the branch point (left; blue is main and one daughter branch; red is the other) and critical conductance value as a function of synapse position in main and one ...

How do rubber (Hevea brasiliensis) plantations behave under seasonal water stress in northeastern Thailand and central Cambodia?

Delineating the characteristics of biosphere-atmosphere exchange in rubber (Hevea brasiliensis Müll. Arg.) plantations, which are rapidly expanding throughout mainland Southeast Asia, is important to understanding the impacts of the land-use change on environmental processes. In attempt to shed new light on the impacts of conversion to rubber, we have conducted eddy flux measurements over a 3-year period in two rubber plantation sites: (1) Som Sanuk, located in northeastern Thailand; and (2) Cambodian Rubber Research Institute (CRRI), located in central Cambodia. Both sites have a distinct dry season. We used a combination of actual evapotranspiration (ET) flux measurements and an inverted version of a simple 2-layer ET model for estimating the mean canopy stomatal conductance (gs). The potential water balance (precipitation (P)−potential evaporation (ET_POT)) for each season (i.e., December–February: DJF, March–May: MAM, June–August: JJA, and September–November: SON) revealed when and how the water use is controlled. In the seasons when actual water balance (P−ET) was negative (DJF and MAM), the deficit was compensated with soil water from the previous season at depths of 0–2m (Thailand site) and 0–3m (Cambodia site). At both sites, the reference value of gs (gsref) and the sensitivity of gs to atmospheric demand (m) appeared to be less in DJF and MAM than each in the other two 3-month periods (seasons). On average, in a whole year, m/gsref was less in Thailand (<<0.6) than in Cambodia (near 0.6 for part of the year), suggesting that there was less sufficient stomatal regulation at the Thailand site, where there might be little risk of water stress-induced hydraulic failure because of its higher annual rainfall amount. In comparison, at CRRI where annual P−ET_POT was negative, there was stricter stomatal regulation, preventing excessive xylem cavitation.

On the Signed Domination Number of the Cartesian Product of Two Directed Cycles

Let D be a finite simple directed graph with vertex set V(D) and arc set A(D). A function is called a signed dominating function (SDF) if for each vertex . The weight of f is defined by . The signed domination number of a digraph D is . Let Cm × Cn denotes the cartesian product of directed cycles of length m and n. In this paper, we determine the exact values of gs(Cm × Cn) for m = 8, 9, 10 and arbitrary n. Also, we give the exact value of gs(Cm × Cn) when m, (mod 3) and bounds for otherwise.

Environmental control of canopy stomatal conductance in a tropical deciduous forest in northern Thailand

Tropical seasonal forests in Southeast Asia are among the most important biomes in terms of global and local hydrologic and carbon fluxes, and their vulnerability to climate change. We conducted eddy flux measurements in a teak (Tectona grandis Linn. f.) plantation in northern Thailand over a 6-year period; this forest undergoes a drastic seasonal change in foliage with somewhat constant incident radiative energy. We used a combination of actual evapotranspiration (ET) flux data and an inversed version of a simple two-layer ET model for estimating the mean canopy stomatal conductance (gs). The main novelty of this analysis is that canopy conductance can be extracted from total surface conductance (including the canopy and forest floor effects), and thus environmental and biological controls of gs are explicitly compared among seasons and years. The relationship between seasonal variations in the leaf area index (LAI) and gs revealed an apparent effect of leaf age on leaf gas exchange capacity: within a year, gs peaked earlier than full-leaf expansion and abruptly declined after the peak of LAI. We used this result to classify three leaf age stages: leaf-out, mid-growing, and leaf-senescence seasons. Then, two ecophysiological parameters, the reference value of gs (gsref), and the sensitivity of gs to atmospheric demand (m), as well as their proportion (m/gsref), were derived from the logarithmic response curve of gs to vapor pressure deficit (VPD) for each season. We showed seasonal variation in gsref as follows: leaf-out season≈mid-growing season>leaf-senescence season. m demonstrated little seasonality and little interannual variation was observed in either parameter. This resulted in a value of almost 0.6 for m/gsref during the leaf-senescence season and of less than 0.6 in the leaf-out and mid-growing seasons, which suggests that the teak trees had strict stomatal regulation to prevent excessive xylem cavitation during the leaf-senescence season (i.e., under drought conditions) and less strict stomatal regulation during the leaf-out and mid-growing seasons (i.e., under moist conditions) when little risk of water stress-induced hydraulic failure would occur. In addition, we obtained a simple linear relationship between soil moisture and gsref, which can be a powerful tool for further research of land–atmosphere interactions using global climate and vegetation dynamics models.

Effect of dust load on the leaf attributes of the tree species growing along the roadside

Dust is considered as one of the most widespread air pollutants. The objective of the study was to analyse the effect of dust load (DL) on the leaf attributes of the four tree species planted along the roadside at a low pollution Banaras Hindu University (BHU) campus and a highly polluted industrial area (Chunar, Mirzapur) of India. The studied leaf attributes were: leaf area, specific leaf area (SLA), relative water content (RWC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), chlorophyll content (Chl), maximum stomatal conductance (Gs(max)), maximum photosynthetic rate (A (max)) and intrinsic water-use efficiency (WUEi). Results showed significant effect of sites and species for DL and the leaf attributes. Average DL across the four tree species was greater at Chunar, whereas, the average values of leaf attributes were greater at the BHU campus. Maximum DL was observed for Tectona grandis at Chunar site and minimum for Syzygium cumini at BHU campus. Across the two sites, maximum value of SLA, Chl and Gs(max) were exhibited by S. cumini, whereas, the greatest value of RWC, LNC, LPC, A (max) and WUEi were observed in Anthocephalus cadamba. A. cadamba and S. cumini exhibited 28 and 27 times more dust accumulation, respectively, at the most polluted Chunar site as compared to the BHU campus. They also exhibited less reduction in A (max) due to dust deposition as compared to the other two species. Therefore, both these species may be promoted for plantation along the roadside of the sites having greater dust deposition.

Variabilidade sazonal da condutância estomática em um ecossistema de manguezal amazônico e suas relações com variáveis meteorológicas

No presente trabalho foram estudadas as variações da condutância estomática (g s) para o período chuvoso (março) e seco (agosto) do ano de 2003, e suas relações de dependência com algumas variáveis meteorológicas medidas em um ecossistema de manguezal amazônico. As informações utilizadas foram do projeto ECOBIOMA, parte integrante do Experimento de Grande Escala da Biosfera-Atmosfera da Amazônia (LBA). A g s acompanha a tendência de variação do balanço de radiação, atingindo valores máximos durante o dia e mínimos durante a noite. A condutância apresentou maiores flutuações no período chuvoso, com valor médio de g s = 0,015 m s-¹, porém com magnitudes inferiores as do período seco. Durante a época seca apresentou um valor médio de g s = 0,027 m s-¹, com menor amplitude, variando de 0,010 &lt; g s &lt; 0,042 m s-¹. As variáveis meteorológicas utilizadas para o estabelecimento de relações de dependência com a variabilidade diária de g s foram déficit de umidade específica (δq), déficit de pressão de vapor (DPV), saldo de radiação (Rn) e velocidade do vento (Vv). O DPV apresentou as melhores correlações com a g s sendo o R² = 0,99 em ambos os períodos. Apesar de também ser importante nas trocas gasosas entre a vegetação e a atmosfera, a Vv apresentou a menor influência na variação média da g s, com um R² = 0,44 para época chuvosa e R² =0,51 para o período seco.

Photosynthetic characteristics of spring ephemerals in the desert ecosystem of Dzungaria Basin, northwest China

Spring ephemerals have the highest photosynthetic rates in higher plants. Gas exchanges and related environmental factors of four typical spring ephemerals, Eremopyrum orientale, Malcolmia scorpioides, Tetracme quadricormis and Arnebia decumbens were measured in their natural environments in the Gurbantunggut Desert of the Dzungaria Basin, northwestern China. Diurnal variations in net photosynthetic rate (P N), transpiration rate (E), stomatal conductance (gs), and water use efficiency (WUE) were analyzed at individual leaf level for these species. P N of E. orientale and M. scorpioides showed a bimodal diurnal pattern, whereas that of T. quadricormis and A. decumbens showed a unimodal pattern, with the maximum value occurred at noon (around 12:00). E of all four species showed a unimodal pattern. Higher WUE in the morning was related to higher P N and lower E. The maximum value of gs appeared in early morning, and then decreased gradually during the daytime. The highest photosynthetically active radiation (PAR) occurred at 14:00, but there was a 2 h lag between the highest temperatures of air and leaf and the highest PAR. The maximum net photosynthetic rate (P Nmax) of the four spring ephemerals were 18.44, 32.03, 33.17, and 20.04 μmolCO2 m−2 s−1, respectively. The present study revealed that the midday depression of photosynthesis of E. orientale and M. scorpioides was mainly due to non-stomatal limitation, whereas that of T. quadricormis and A. decumbens was mainly due to stomatal limitation during 14:00–16:00 followed by non-stomatal limitation after 16:00. Our results illustrated that the change of E was consistent with the diurnal fluctuation of air temperature, but the diurnal change of P N was affected by the whole microclimate, i.e. temperature, relative humidity (RH), PAR, etc.

Modeling Stomatal Conductance and Photosynthesis of a Flag Leaf of Wheat under Elevated O3 Concentration

In aims to estimate stomatal O3 flux and predict the yield loss of wheat in eastern China, the focus was on developing a stomatal conductance (gs) model and a photosynthesis (P) model of a wheat flag leaf. To date, relationships between the relative yield of European spring wheat and the stomatal O3 flux of the wheat flag leaf have been presented by Pleijel et al. (2000), UNECE (2004) and many researchers with high correlations on the basis of the open-top chamber experiments.The gs and P of flag leaves and other winter wheat leaves were measured, both in the ambient field and FACE (Free Air Concentration Enrichment) field, whereby the O3 concentration ([O3]) was artificially elevated, on 6 days from before heading to before harvest, 2008. The gs model was developed by a multiplicative approach with a maximum value of gs (gsmax) multiplied by modifications of photosynthetically active radiation incident on the leaf (PARl), accumulated exposure of O3 over a threshold concentration of 40 ppb for daylight hours (AOT40) at the canopy top, phenology, VPD and the time of day. A relationship between gs/gsmax and P/Pmax (Pmax is the maximum value of P) of a flag leaf measured in PARl=2000 μmol m-2 s-1 was represented by a linear regression line with a slope of 1.0 and intercept of 0.0. Therefore, the P model was developed by the multiplicative approach with Pmax multiplied by modifications of PARl for P and the same other parameters as the gs model. The models reproduced the gs and P of a flag leaf and even those of the other leaves successfully.For the practical use of these models, [O3] at the canopy top ([O3]canopy) and PARl were also modeled. By applying the logarithmic profile of [O3] above the canopy, and modeling the roughness length for [O3] (z0O3) with the wind speed, the [O3]canopy was reproduced successfully. To model PARl, the inclination factor of a leaf (Fl) was decided so that the modeled vertical profile of shortwave radiation within the canopy could fit the measurements using the vertical two streams shortwave radiation model (e.g. Oue, 2003a; 2003b). Fl at z=0.6-0.8 m, where most flag leaves exist, was found to be from 0.4 to 0.6 for a wheat canopy of LAI=5.

A general method of parameterizing the big‐leaf model to predict the dry‐canopy evaporation rate of individual coniferous forest stands

AbstractThis study proposes a general method of parameterizing the big‐leaf model that is applicable to estimation of daytime dry‐canopy evaporation (hereafter, evaporation) rates of coniferous forest stands without observed flux data. The method considers variation in the reference value of surface conductance Gs between individual stands by incorporating a relationship between canopy height and reference Gs values reported by Komatsu (2003c) [Hydrological Processes 17: 2503–2512]. However, the method does not consider variation in modifier functions of Gs and in aerodynamic conductance Ga between individual stands.We examined the validity of the method based on daytime evaporation rate data for 26 coniferous stands. The method showed greater predictability than another method that ignores variation in reference Gs values between individual stands. This illustrates the validity of considering variation in reference Gs values between individual stands. Model predictability was not enhanced by considering variation in modifier functions of Gs and Ga between individual stands. This illustrates the validity of ignoring variation in modifier functions of Gs and Ga between individual stands.The method is applicable to stands with projected LAI ≥ 3·0 and canopy height &lt;c. 30 m. The method can result in errors when applied outside these limitations. Regardless, the method should be valuable for estimating daytime evaporation rates of coniferous stands, as many stands fall within these limitations. The method is applicable to evaporation rate estimates in growing seasons without soil water stress when dry‐canopy evaporation significantly affects the forest water cycle. At this stage, the method can result in errors when applied outside this limitation. However, the method should be valuable as a basis for developing a more comprehensive method applicable outside this limitation. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Relationship between canopy height and the reference value of surface conductance for closed coniferous stands

AbstractWhen estimating the dry‐canopy evaporation rate of coniferous stands using the Penman–Monteith equation, it is crucial to determine the reference value of surface conductance Gs. This paper examines the relationship between canopy height and the reference value of Gs based on the maximum value of Gs with a vapour pressure deficit ≥ 1·0 kPa, Ĝs max. There is a clear correlation between canopy height and Ĝs max when the projected leaf area index ≥3·0. This suggests that using this relationship will enable more accurate determination of the reference value of Gs for closed stands. Copyright © 2003 John Wiley &amp; Sons, Ltd.

Viscoelastic Behavior of a Supramolecular Polymeric System Consisting of Tri-3,7-dimethyloctyl cis-1,3,5-cyclohexanetricarboxamide and n-Decane

Viscoelastic behavior of a supramolecular polymeric system, so-called an organogel, consisting of tri-3,7-dimethyloctyl cis-1,3,5-cyclohexanetricarboxamide (DO3CH) and n-decane (C10) was examined varying the concentration of DO3CH (c) and temperature ranged from 20 to 50°C. The obtained storage and loss moduli for the system were well described with the sum of two Maxwell models possessing two sets of a relaxation time and strength: τf and Gf, and τs (>τf) and Gs, whereas the viscoelastic behavior of organogels consisting of N, N', N"-tris(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide (DO3B) and n-alkanes is well described with only one Maxwell model. The value of Gf is proportional to c2 as observed in entangled flexible polymer systems and the organogels of DO3B. On the contrary, the value of Gs is approximately proportional to c1.3 similarly to the behavior predicted for rigid rodlike polymer solutions. The value of τf is essentially independent of c, while that of τs is kept at a constant and is followed by increasing above c = 10 gL−1. The activation energies of both the relaxation times are less than that for the viscosity of C10. Supramolecular polymeric structure bearing 2-type, rigid rodlike and flexible, portions are generated in the system due to intermolecular hydrogen bonding. The fast relaxation mode is attributed to the entanglement release between the flexible portions as observed in the organogels of DO3B, and the other is attributed to rotational relaxation of the rigid rodlike portion.

Water relations and hydraulic control of stomatal behaviour in bell pepper plant in partial soil drying

ABSTRACTTwo experiments, a split‐root experiment and a root pressurizing experiment, were performed to test whether hydraulic signalling of soil drying plays a dominant role in controlling stomatal closure in herbaceous bell pepper plants. In the split‐root experiment, when both root parts were dried, synchronous decreases in stomatal conductance (gs), leaf water potential (LWP) and stem sap flow (SFstem) were observed. The value of gs was found to be closely related to soil water potential (SWP) in both compartments. Tight relationships were observed between gs and stem sap flow under all conditions of water stress, indicating a complete stomatal adjustment of transpiration. When the half‐root system has been dried to the extent that its water uptake dropped to almost zero, declines in gs of less than 20% were observed without obvious changes in LWP. The reduced plant hydraulic conductance resulting from decreased sap flow and unchanged LWP may be a hydraulic signal controlling stomatal closure; the results of root pressurizing supported this hypothesis. Both LWP and gs in water‐stressed plants recovered completely within 25 min of the application of root pressurizing, and decreased significantly within 40 min after pressure release, indicating the hydraulic control of stomatal closure. Our results are in contrast to those of other studies on other herbaceous species, which suggested that chemical messengers from the roots bring about stomatal closure when plants are in water stress.

The role of strange sea quarks on neutrino-nucleus reactions in Superkamiokande and in the supernova r-process

We study the influence of a strange axial vector form factor Gs of the nucleon on the neutrino-induced proton and neutron knockout of 16O. In particular, we calculate how much Gs≠0 might affect the recently proposed signal for supernova νμ and ντ neutrinos in the Superkamiokande detector. We discuss whether Superkamiokande might be able to determine the value of Gs in a hypothetical neutrino-beam experiment. Finally we comment on the possible effect Gs≠0 might have on neutrino-nucleus cross sections in the neutrino-driven wind model for the nuclear r-process.

Stomatal conductance and transpiration in shoots of Scots pine after 4-year exposure to elevated CO2 and temperature

Single Scots pines (Pinus sylvestris L.) trees were subjected to elevated temperature (year-round elevation), elevated CO2 (elevation from April 15 to September 15), and a combination of elevated temperature and CO2, for 4 years in open-topped chambers. Measurements and modelling were performed to determine if long-term growth at elevated CO2 concentration and temperature altered water use efficiency (WE) and the responses of stomatal conductance (gs) to photon flux density (Qp), the leaf-to-air vapour pressure difference (Dv), leaf temperature (Tl), and intercellular concentration of CO2 (Ci). Long-term elevation of CO2 led to a significant decline in the absolute value of gs at almost all levels of Qp, Dv, Ci, and Tl. Elevated temperature treatment increased the absolute value of gs only at higher Dv and Tl. The effect of the combination of elevated CO2 and temperature did not appear as a mean of the effects of the two single factors, while there was an interaction between the two factors. The modifications in the sensitivity of stomata, resulting from different treatments, did not have the same pattern as the change in gs, but depended on levels of Qp, Dv, and Tl. Compared with the control treatment, elevated concentration of CO2 or a combination of elevated CO2 and temperature led, on average, to 50 and 30% increases in WE, respectively, which can be attributed mainly to an increase in the rate of net assimilation. In contrast, elevated temperature alone did not significantly change WE, although transpiration rate was increased. Key words: long-term CO2 and temperature elevation, stomatal conductance, transpiration, water use efficiency, Pinus sylvestris.