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1.
Magnetic field-dependent recombination measurements together with magnetic field-dependent triplet lifetimes (Chidsey, E.D., Takiff, L., Goldstein, R.A. and Boxer, S.G. (1985) Proc. Natl. Acad. Sci USA 82, 6850–6854) yield a free energy change Δ G(P +H − − 3P*) = 0.165 eV ±0.008 at 290 K. This does not depend on whether nuclear spin relaxation in the state 3P* is assumed to be fast or slow compared to the lifetime of this state. This value, being (almost) temperature independent, indicates Δ G(P +H − − 3P*) Δ H(P +H − − 3P*) and is consistent with Δ G( 1P* − P +H −) and Δ H( 1P* − 3P*) from previous delayed fluorescence and phosphorescence data, implying Δ G Δ H for all combinations of these states. 相似文献
2.
Genetic resistance to vesicular-arbuscular (VA) mycorrhiza formation has been obtained in spontaneous or chemically induced mutants of two mycorrhiza-forming species ( Pisum sativum L. and Vicia faba L.). The eight mutants, termed myc −, are characterized by aborted infections limited to one or two host cells. Expression of the myc − character is associated with that of the nod − character in both legumes, and is likewise under recessive genetic control. Preliminary analysis of the genetic behaviour of the myc − mutants in diallel crosses has shown that at least three genes are involved in VA mycorrhiza infection. 相似文献
3.
The reactions of complex (C 5Me 5)Ir(Cl) (CO) (Me) (1a) with cyclohexylisocyanide and phosphines (L=CyNC, PHPh 2, PMePh 2, PMe 2Ph) give the products of alkyl migratory insertion (C 5Me 5Ir(Cl) (COMe) (L), in toluence or tetrahydrofuran at 323 K or higher temperature. The phenyl analogue (C 5Me 5)Ir(Cl)(CO)(Ph) or the iodide complexes (C 5Me 5)Ir(I) (CO) (R) (R=Me, Ph_are not reactive under the same conditions. The reaction of (C 5Me 5)Ir(Cl)(CO)(Me) with PMePh 2 and PMe 2Ph in acetonitrile yields the chloride substitution product [(C 5Me 5)Ir(CO)(L)(Me)] +Cl −. Kinetic measurements for the reactions of (C 5Me 5)Ir(Cl)(CO)(Me) in toluene are first order in the iridium complex and exhibit a saturation dependence on the incoming donors L. Analysis of the data suggests a two-step process involving (i) rapid formation of a molecular complex [(C 5Me 5)Ir(Cl)(CO)(Me), (L)], in which the structure of 1a is unperturbed within the limits of spectroscopic analysis, and (ii) rate determining methyl migration. The reaction parameters are K for the pre-equilibrium step ( K = 1.5 (CyNC), 7.3 (PHPh 2), 7.1 (PMePh 2) dm 3 mol −1 at 323 K) and k2 for the slow carbon---carbon bond formation ( k2 (10 5) = 6.9 (CyNC), 1.2 (PHPh 2), 1.0 (PMePh 2) s −1 at 323 K). The activation parameters for the methyl migration step in the reaction with PMePh 2 obtained between 308 and 338 K, are Δ H≠ = 106±16 kJ mol −1 and Δ S≠ = − 14±5 J K −1 mol −1. The reaction of 1a with PMePh 2 proceeds at similar rates in tetrahydrofuran ( K = 3.7 dm 3 mol −1, k2 (10 5) = 1.2 s −1, 323 K). The crystal structure of (C 5Me 5)Ir(Cl)(COMe) (PMe 2Ph) has been determined by X-ray diffraction. C 20H 29ClOPIr: Mr = 544.1, monoclinic, P2 1/ n, A = 8.084 (2), B = 9.030(2), C = 28.715 (3) Å, β = 91.41 (3)°, Z = 4, Dc = 1.71 g cm −3, V = 2095.5 Å 3, room temperatyre, Mo K, γ = 0.71069, μ = 65.55 cm −1, F(000) = 1044, R = 0.037 for 2453 independent observed reflections. The complex shows a deformed tetrahedral coordination assuming the η 5-C 5Me 5 molecular fragment as a single coordination site. The iridium-chlorine bond is staggered with respect to two adjacent C(ring)-methyl bonds, while the Ir---P and the Ir---COMe bonds are eclipsed with respect to C(ring)-methyl bonds. 相似文献
4.
The photosynthetic capacity of Myriophyllum salsugineum A.E. Orchard was measured, using plants collected from Lake Wendouree, Ballarat, Victoria and grown subsequently in a glasshouse pond at Griffith, New South Wales. At pH 7.00, under conditions of constant total alkalinity of 1.0 meq dm −3 and saturating photon irradiance, the temperature optimum was found to be 30–35°C with rates of 140 μmol mg −1 chlorophyll a h −1 for oxygen production and 149 μmol mg −1 chlorophyll a h −1 for consumption of CO 2. These rates are generally higher than those measured by other workers for the noxious Eurasian water milfoil, Myriophyllum spicatum L., of which Myriophyllum salsugineum is a close relative. The light-compensation point and the photon irradiance required to saturate photosynthetic oxygen production were exponentially dependent on water temperature. Over the temperature range 15–35°C the light-compensation point increased from 2.4 to 16.9 μmol (PAR) m −2 s −1 for oxygen production while saturation photon irradiance increased from 41.5 to 138 μmol (PAR) m −2 s −1 for oxygen production and from 42.0 to 174 μmol (PAR) m −2 s −1 for CO 2 consumption. Respiration rates increased from 27.1 to 112.3 μmol (oxygen consumed) g −1 dry weight h −1 as temperature was increased from 15 to 35°C. The optimum temperature for productivity is 30°C. 相似文献
5.
The phosphinoalkenes Ph 2P(CH 2) nCH=CH 2 ( n= 1, 2, 3) and phosphinoalkynes Ph 2P(CH 2) n C≡CR (R = H, N = 2, 3; R = CH 3, N = 1) have been prepared and reacted with the dirhodium complex (η−C 5H 5) 2Rh 2(μ−CO) (μ−η 2−CF 3C 2CF 3). Six new complexes of the type (ν−C 5H 5) 2(Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3)L, where L is a P-coordinated phosphinoalkene, or phosphinoalkyne have been isolated and fully characterized; the carbonyl and phosphine ligands are predominantly trans on the Rh---Rh bond, but there is spectroscopic evidence that a small amount of the cis-isomer is formed also. Treatment of the dirhodium-phosphinoalkene complexes with (η−CH 3C 5H 4)Mn(CO) 2thf resulted in coordination of the manganese to the alkene function. The Rh 2---Mn complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2P(CH 2) 3CH=CH 2} (η−CH 3C 5H 4)Mn(CO) 2] was fully characterized. Simi treatment of the dirhodium-phosphinoalkyne complexes with Co 2(CO) 8 resulted in the coordination of Co 2(CO) 6 to the alkyne function. The Rh 2---Co 2 complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2PCH 2C≡CCH 3}Co 2(CO) 2], C 37H 25Co 2F 6O 7PRh 2, was fully characteriz spectroscopically, and the molecular structure of this complex was determined by a single crystal X-ray diffraction study. It is triclinic, space group
( Ci1, No. 2) with a = 18.454(6), B = 11.418(3), C = 10.124(3) Å, = 112.16(2), β = 102.34(3), γ = 91.62(3)°, Z = 2. Conventional R on | F| was 0.052 fo observed ( I > 3σ( I)) reflections. The Rh 2 and Co 2 parts of the molecule are distinct, the carbonyl and phosphine are mutually trans on the Rh---Rh bond, and the orientations of the alkynes are parallel for Rh 2 and perpendicular for Co 2. Attempts to induce Rh 2Co 2 cluster formation were unsuccessful. 相似文献
6.
The structure of the 7S globulin from Phaseoulus vulgaris L in dilatue solutions has been studied by small angle X-ray scattering (SAXS), by quasi-elastic light scattering (Q ELS), by circular dichroism spectroscopy (c.d.), and by precise density measurements. The molar mass, the radius of gyration, the volume, the maximum dimension and the diffusion coefficient were determined as M = 1.45 × 10 5 g mol −1, R G = 4.05 nm, V = 300- nm 3, L = 13.0 nm and D20,w0 = 4.5 × 10 −7 cm2 s−1, respectively. The molecule has an asymmetrical shape with the dimensions 12.5 × 12.5 × 3.75 nm. The secondary structure of the 7S globulin is characterized by a small portion of -helical structure (14%) and a marked content of β-structure (18%). 相似文献
7.
Combined effects of UVB radiation and CO 2 concentration on plant reproductive parts have received little attention. We studied morphological and physiological responses of siliquas and seeds of canola ( Brassica napus L. cv. 46A65) to UVB and CO 2 under four controlled experimental conditions: UVB radiation (4.2 kJ m −2 d −1) with ambient level of CO 2 (370 μmol mol −1) (control); UVB radiation (4.2 kJ m −2 d −1) with elevated level of CO 2 (740 μmol mol −1); no UVB radiation (0 kJ m −2 d −1) with ambient level of CO 2 (370 μmol mol −1); and no UVB radiation (0 kJ m −2 d −1) with elevated level of CO 2 (740 μmol mol −1). UVB radiation affected the outer appearance of siliquas, such as colour, as well as their anatomical structures. At both CO 2 levels, the UVB radiation of 4.2 kJ m −2 d −1 reduced the size of seeds, which had different surface patterns than those from no UVB radiation. At both CO 2 levels, 4.2 kJ m −2 d −1 of UVB decreased net CO 2 assimilation ( AN) and water use efficiency (WUE), but had no effect on transpiration ( E). Elevated CO 2 increased AN and WUE, but decreased E, under both UVB conditions. At both CO 2 levels, the UVB radiation of 4.2 kJ m −2 d −1 decreased chlorophyll fluorescence, total chlorophyll (Chl), Chl a and Chl b, but had no effect on the ratio of Chl a/ b and the concentration of UV-screening pigments. Elevated CO 2 increased total Chl and the concentration of UV-screening pigments under 4.2 kJ m −2 d −1 of UVB radiation. Neither UVB nor CO 2 affected wax content of siliqua surface. Many significant relationships were found between the above-mentioned parameters. This study revealed that UVB radiation exerts an adverse effect on canola siliquas and seeds, and some of the detrimental effects of UVB on these reproductive parts can partially be mitigated by CO 2. 相似文献
8.
The effect of dilution rate on the production of lactic acid from whey permeate by Lactobacillus helveticus has been investigated. In the first chemostat of a two-stage system, total conversion (98.1%) and maximum lactic acid concentration (43.7 g l −1) were obtained at a dilution rate ( DItot) of 0.06 h −1. Maximum volumetric productivities of lactic acid (8.27 g l −1 h −1) and biomass (1.90 g l −1 h −1) occurred at DItot of 0.40 h −1. The fraction of
-lactate in the product was found to increase with dilution rate and reached a maximum of 66% at the same dilution rate. The maximum specific growth rate (μ max) on this medium was 0.7 h −1. A Y ATP (max) value of 22.4 g dry weight (mol ATP) −1 and a maintenance coefficient of 8.0 mmol ATP (g dry weight h) −1 were determined. The second stage, in series with the first, confirmed these results and further showed that the total residence time could be reduced by 50%, compared with a single chemostat for the same nearly complete level of substrate conversion. 相似文献
9.
The effects of different external nitrate concentrations (0 (control), 1, 50, 100, 500, 1000 and 20 000 mmol m −3) on growth, nodulation and nitrate-reductase activity (NRA) of inoculated Neptunia plena (L.) Benth. were examined. Plants given 500 and 1000 mmol m−3 nitrate had greater (P < 0.05) shoot length, leaf, stem and root dry mass, and carbon and nitrogen contents than the controls and plants given 20 000 mmol m−3 nitrate. Nodule number was not significantly affected by nitrate concentration up to 50 mmol m−3, but 100 mmol m−3 nitrate reduced nodulation by 68% and concentrations above 100 mmol m−3 completely inhibited nodule development. Plants given 100–20000 mmol m−3 nitrate had a greater nitrate content per g leaf, stem and root dry mass (DM) than controls. Nitrate per g root DM did not increase with external nitrate concentration above 500 mmol m−3, but levels in leaf and stem were greater at 20 000 mmol m−3 nitrate than at all other concentrations. NRA per g leaf, stem and root fresh mass (FM) was greater for plants given 500–20000 mmol m−3 than for controls, but there was no significant increase with nitrate concentration above 500 mmol m−3. Substantial proportions of total plant nitrate and NRA were found in both root and shoot over the entire range of external nitrate concentrations given. Findings for N. plena are compared with data obtained previously for terrestrial legumes. 相似文献
10.
The Akt signaling pathway controls several cellular functions in the cardiovascular system; however, its role in atherogenesis is unknown. Here, we show that the genetic ablation of Akt1 on an apolipoprotein E knockout background ( ApoE−/−Akt1−/−) increases aortic lesion expansion and promotes coronary atherosclerosis. Mechanistically, lesion formation is due to the enhanced expression of proinflammatory genes and endothelial cell and macrophage apoptosis. Bone marrow transfer experiments showing that macrophages from ApoE−/−Akt1−/− donors were not sufficient to worsen atherogenesis when transferred to ApoE−/− recipients suggest that lesion expansion in the ApoE−/−Akt1−/− strain might be of vascular origin. In the vessel wall, the loss of Akt1 increases inflammatory mediators and reduces eNOS phosphorylation, suggesting that Akt1 exerts vascular protection against atherogenesis. The presence of coronary lesions in ApoE−/−Akt1−/− mice provides a new model for studying the mechanisms of acute coronary syndrome in humans. 相似文献
11.
A change-over design was used to measure the effect of 0.0, 2.5 and 5.0 kg day −1 of ground corn ( Zea mays L.) kernels on the ingestive behavior of 12 tethered 2-year-old Angus ( Bos taurus) heifers receiving a basal grain ration of 2.5 kg day −1 and grazing summer regrowth pastures of ‘Boone’ orchardgrass ( Dactylis glomerata L.). The experimental design allowed the estimation of the immediate effects (direct effects) of grain on ingestive behavior, its carry-over effects expressed the next day (first residual effects), and the combined effects of direct and first residual effects (permanent effects). Grain had no direct effect on ingestive behavior. Heifers ingested herbage dry matter (DM) at 1.64 kg h −1, forming bites of 745 mg DM at 37 bites min −1. The first residual effect was significant for residual dry matter, utilization, intake and rate of biting. Five kg of grain depressed the rate of herbage DM intake from 1.67 to 1.50 kg DM h −1 on the day following its ingestion. This residual effect was not expressed in herbage intake per bite, but rate of biting was reduced from 39 to 35 bites min −1. The 2.5-kg treatment had a small positive residual effect on rate of herbage intake. Data indicate the operation of energy balance regulation mechanisms on the ingestive behavior of grazing beef cattle. 相似文献
12.
The rate of electron transfer between reduced cytochrome ƒ and plastocyanin (both purified from parsley) has been measured as k = 3.6 · 10 7 M −1 · s −1, at 298 °K and pH 7.0, with activation parameters Δ H‡ = 44 kJ · mole −1 and Δ S‡ = +46 J · mole −1 · °K −1. Replacement of cytochrome ƒ with red algal cytochrome c-553, Pseudomonas cytochrome c-551 and mammalian cytochrome c gave rates at least 30 times slower: k = 5 · 10 5, 7.5 · 10 5 and 1.0 · 10 6 M −1 · s −1, respectively. Similar measurements made with azurin instead of plastocyanin gave k = 6 · 106 and approx. 2 · 107 M−1 · s−1 for reaction of reduced azurin with cytochrome ƒ and algal cytochrome respectively. Rate constants of 115 and 80 M−1 · s−1 were found for reduction of plastocyanin by ascorbate and hydroquinone at 298 °K and pH 7.0. The rate constants for the oxidation of plastocyanin, cytochrome ƒ, Pseudomonas cytochrome c-551 and red algal cytochrome c-553 by ferricyanide were found to be between 3 · 104 and 8 · 104 M−1 · s−1. The results are discussed in relation to photosynthetic electron transport. 相似文献
13.
Light and temperature-response curves and their resulting coefficients, obtained within ecophysiological characterization of gas exchanges at the leaf level, may represent useful criteria for breeding and cultivar selection and required tools for simulation models aimed at the prediction of potential plant behaviour in response to environmental conditions. Leaf-scale gas exchanges, by means of an IRGA open-flow system, were measured in response to light intensity (8 levels from 0 up to 2000 μmol m−2 s−1), CO2 concentrations (ambient—350 μmol mol−1 and short-term enriched—700 μmol mol−1) and air temperature (from 7 up to 35 °C) on three Vicia faba L. genotypes, each representing one of the three cultivated groups: major, equina and minor. The net assimilation rate response to light intensity was well described by an exponential rise to max function. The short-term CO2 enrichment markedly increased the values of light response curve parameters such as maximum photosynthetic rate (+80%), light saturation point (+40%) and quantum yield (+30%), while less homogenous behaviour was reported for dark respiration and light compensation point. For each light intensity level, the major and minor genotypes studied showed assimilation rates at least a 30% higher than equina. The positive effects of short-term CO2 enrichment on photosynthetic water use efficiency (WUE) indicate a relevant advantage in doubling CO2 concentration. In the major and minor genotypes studied, similar assimilation rates, but different WUE were observed. The optimum leaf temperature for assimilation process, calculated through a polynomial function, was 26–27 °C and no relevant limitations were observed in the range between 21 and 32 °C. Analysis at the single leaf level provided both rapid information on the variations in gas exchange in response to environmental factors and selection criteria for the screening of genotypes. 相似文献
14.
Bacillus species carrying s ubC gene encoding serine alkaline protease (SAP) enzyme were developed in order to increase the yield and selectivity in the bioprocess for SAP production. For this aim, s ubC gene was cloned into pHV1431 Escherichia coli– Bacillus shuttle vector, and transferred into nine host Bacillus species, i.e. B. alvei, B. amyloliquefaciens, B. badius, B. cereus, B. coagulans, B. firmus, B. licheniformis, B. sphaericus and B. subtilis. The influence of the host Bacillus species on SAP production on a defined medium with glucose was investigated in bioreactor systems. For each of the recombinant (r-) Bacillus species, effects of initial glucose concentration on cell growth and SAP production were investigated; and, physiological differences and similarities between the wild-type and r- Bacillus species are discussed. The highest biomass concentration was obtained with r- B. coagulans as 3.8 kg m −3 at the initial glucose concentration of CGo=20 kg m −3 and the highest volumetric SAP activity was obtained with r- B. amyloliquefaciens as 1650 U cm −3 at CGo=20 kg m −3. Overall SAP activity per amount of substrate consumed was the highest for r- B. sphaericus (137 U g −1 cm −3) and r- B. licheniformis (130 U g −1 cm −3). Among the r- Bacillus species the highest activity increase compared to the wild types was obtained with r- B. sphaericus while the lowest increase was obtained with r- B. amyloliquefaciens and r- B. licheniformis due to high SAP production potential of the wild-type strains. During storage of the host microorganisms, r- B. alvei and r- B. amyloliquefaciens were not able to bear the recombinant plasmid, probably, due to the restriction enzymes synthesized. Due to the highest stable volumetric activities r- B. licheniformis (950 U cm −3) and r- B. sphaericus (820 U cm −3) appear to be the favorable hosts for the production of SAP. All the r- Bacillus species excreted organic acids oxaloacetic and succinic acids, but, none excreted the amino acid valine. The variations in by-product distributions with each recombinant organism were also discussed. 相似文献
15.
The aim of our study was to determine whether a meal modifies the antisecretory response induced by PYY and the structural requirements to elicit antisecretory effects of analogue PYY(22–36) for potential antidiarrhea therapy. The variations in short-circuit current (Isc) due to the modification of ionic transport across the rat intestine were assessed in vitro, using Ussing chambers. In fasted rats, PYY induced a dose- and time-dependent reduction in Isc, with a sensitivity threshold at 5 × 10 −11 M (ΔIsc −2 ± 0.5 μA/cm 2). The reduction was maximal at 10 −7 M (Isc −23 ± 2 μA/cm 2), and the concentration producing half-maximal inhibition was 10 −9 M. At 10 −7 M, reduction of Isc by PYY reached 90% of response to 5 × 10 −5 M bumetanide. The PYY effect was partly reversed by 10 −5 M forskolin (Isc +13.43 ± 2.91 μA/h·cm 2, p < 0.05) or 10 −3 M dibutyryl adenosine 3′,5′ cyclic monophosphate (Isc +12 ± 1.69 μA/cm 2, p < 0.05). Naloxone and tetrodotoxin did not alter the effect of PYY. In addition, PYY and its analogue P915 reduced net chloride ion secretion to 2.85 and 2.29 μEq/cm 2 ( p < 0.05), respectively. The antisecretory effect of PYY was accompanied by dose- and time-dependent desensitization when jejunum was prestimulated by a lower dose of peptide. The antisecretory potencies exhibited by PYY analogues required both a C-terminal fragment (22–36) and an aromatic amino acid residue (Trp or Phe) at position 27. At 10 −7 M the biological activity of PYY was lower in fed than fasted rats ( p < 0.001). Our results confirm the antisecretory effect of PYY, but show that the fed period is accompanied by desensitization, similar to the transient desensitization observed in the fasted period with cumulative doses. This suggests that PYY may act as a physiological mediator that reduces intestinal secretion. 相似文献
16.
Floating Pennywort ( Hydrocotyle ranunculoides L. fil.) is a worldwide distributed aquatic plant. The species is native to North America and quite common also in Central and South America. In Europe, Japan and Australia it is known as an alien plant, sometimes causing serious problems for affected ecosystems and human use of water bodies. Starting from Western Europe with an eastwards directed spread, Floating Pennywort was recorded in Germany in 2004 for the first time. Since then, the species spread out and got established in western parts of Central Europe. For a definite prediction of the potential of a further spread, data about biology, in particular growth and photosynthesis are needed. Here, regeneration capacity, growth at different nutrient availabilities and photosynthesis of H. ranunculoides were investigated. In addition biomass samples were taken in the field. Results show an enormous regeneration capacity (e.g., by forming new shoots from small shoot fragments), increasing growth rates under increasing nutrient availability and a maximum increase of biomass reaching 0.132±0.008 g g −1 dw d −1. Dense populations of H. ranunculoides growing in ponds and oxbows were found at high nutrient content of the substrate, the biomass reaching there up to 532.4±14.2 g dw m −2. Gas exchange analysis showed a physiological optimum of H. ranunculoides CO 2 uptake at temperatures between 25 and 35 °C and high photon flux densities (PPFD) above 800 μmol photons m −2 s −1. In comparison, native Hydrocotyle vulgaris showed an optimum of net photosynthesis at 20–30 °C and a light saturation of CO 2 gas exchange at 350 μmol photons m −2 s −1. 相似文献
17.
Biogas-plant effluent collected from a KVIC model biogas-plant fed on cattle waste was utilised in fish polyculture. Biogas-plant effluent was applied at 0·15% concentration at 3-day intervals. The growth rate of Labeo rohita was 4·52 ±0 ·75 g fish −1 day −1, of Cirrhina mrigala 3·36 ± 0·48 g fish − day −1 and of Cyprinus carpio was 1·82 ± 0·41 g fish −1 day −1. Total fish production was 13·44 ± 0·77 kg 0·002 ha −1 year −1 (6653 kg ha −1 year −1) without any supplementary fish-feed. 相似文献
18.
Ring segments of rat middle cerebral artery (MCA) were prepared for measurement of isometric force and precontracted with 10 −4 M uridine triphosphate (UTP). Concentration-effect curves (CEC) were constructed for bradykinin (BK, 10 −8–10 −5 M) in segments with functionally intect (E+) or denuded (E−) endothelium. E− segments did not dilate to BK. The BK receptor was characterized by application of specific B 1 or B 2 antagonists [des-Arg 9-Leu 8] BK (10 −5 M) and [
-Arg 0-Hyp 3-Thi 5-
-Tic 7-Oic 8] BK (HOE140,3 × 10 −7 M), respectively, or B 1 agonist [des-Arg 9] BK (10 −8–10 −4 M). Involvement of nitric oxide (NO) was tested with NG-nitro-
-arginine (LNNA, 10 −4 M). BK induced concentration-dependent relaxation with a maximal effect ( Emax) of 40.86 ± 1.50% at 10 −6 M and a pD 2 (−log 10 EC 50) of 6.818 ± 0.044. This relaxation could be prevented with HOE140 or LNNA, but was not influenced by [des-Arg 9-Leu 8] BK. [des-Arg 9] BK did not induce any effect. These results demonstrate that BK induced relaxation via endothelial B 2 receptors and release of NO in isolated rat MCA. 相似文献
19.
Complexes of type A 4[VO(tart)] 2· nH 2O, where A = Rb or Cs and tart = d, l-tartrate(4−) ( n = 2) or d,d-tartrate(4−) ( n = 2 for Rb and n = 3 for Cs), were prepared from an aqueous mixture of V 2O 5, AOH and H 4tart. These complexes were studied by single-crystal X-ray diffraction methods: Rb 4[VO( d, l-tart)] 2·2H 2O, space group P1 with a = 8.156(1), b = 8.246(1), c = 8.719(1)Å, = 66.09(1)°, β = 65.07(1)°, γ = 82.40(1)°, Z = 2, 1917 observed reflections, and final Rw = 0.035; Cs 4[VO( d, l-tart)] 2·2H 2O, space group P21/ c with a = 9.350(1), b = 13.728(2), c = 8.479(1)Å, β = 106.77(1)°, Z = 4, 2235 observed reflections, and final Rw = 0.054; Rb 4[VO( d, d-tart)] 2·2H 2O, space group P4122 with a = 8.072(1), c = 32.006(3)Å, Z = 8, 1014 observed reflections and final Rw = 0.038; Cs 4[VO( d, d-tart)] 2·3H 2O, space group P122 with a = 8.184(1), c = 33.680(5)Å, Z = 8, 1310 observed reflections, and final Rw = 0.063. Bulk magnetic susceptibility data (1.5–300 K) for these compounds and A 4[VO l, l-tart)] 2· nH 2O (A = Rb, Cs) were obtained on polycrystalline samples. These data were analyzed in terms of a Van Vleck exchange coupled S = 1/2 model which was modified to include an interdimer exchange parameters Θ. Analysis of the low-temperature (1.5–20 K) susceptibility data gave 2 J = +1.30 cm −1 and Θ = −1.86 K for Rb 4[VO( d, l-tart)] 2·2H 2O, 2 J = +1.16 cm −1 and Θ = −1.69 K for Cs 4[VO( d, l-tart)] 2·2H 2O, 2 J = +1.90 cm −1 and Θ = −0.82 K for Rb 4[VO( d, d-tart)] 2·2H 2O, 2 J = +2.04 cm −1 and Θ = −0.80 K for Rb 4[VO( l, l-tart)] 2·2H 2O, 2 J = +1.52 cm −1 and Θ = −0.25 K for Cs 4[VO( d, d-tart)] 2·3H 2O, and 2 J = +1.64 cm −1 and Θ = −0.31 K for Cs 4[VO( l, l-tart)] 2·3H 2O. These results suggest the magnitudes of intradimer (ferromagnetic and interdimer (antiferromagnetic) exchange interactions are similar in these complexes, as observed for the analogous Na salts. 相似文献
20.
The effects of oxygen supply within the range 20.8–50% (using pure oxygen and air), on cell cultures of Panax ginseng were investigated in a balloon-type bubble bioreactor (5 L capacity, containing 4 L Murashige and Skoog medium, supplemented with 7.0 mg L −1 indolebutyric acid, 0.5 mg L −1 kinetin and 30 g L −1 sucrose). A 40% oxygen supply was found to be optimal for the production of both cell mass and saponin yielding values of 12.8 g (DW) L −1, 4.5 mg (g DW) −1 on day 25, respectively. Low (20.8%, 30%) and high (50%) oxygen concentration supplies were unfavorable to cell growth and saponin accumulation. The results indicate that oxygen supplementation to bioreactor-based ginseng cultures was beneficial for biomass accumulation and saponin production. 相似文献
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