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1.
The memory effect (the dependence of the dynamic breakdown voltage U b on the time interval τ between voltage pulses) in pulse-periodic discharges in pure argon and the Ar + 1%N 2 mixture was studied experimentally. The discharge was ignited in a 2.8-cm-diameter tube with an interelectrode distance of 75 cm. The measurements were performed at gas pressures of P = 1, 2, and 5 Torr and discharge currents in a steady stage of the discharge of I = 20 and 56 mA. Breakdown was produced by applying positive-polarity voltage pulses, the time interval between pulses being in the range of τ = 0.5–40 ms. In this range of τ values, a local maximum (the anomalous memory effect) was observed in the dependence U b (τ). It is shown that addition of nitrogen to argon substantially narrows the range of τ values at which this effect takes place. To analyze the measurement results, the plasma parameters in a steady-state discharge (in both pure argon and the Ar + 1%N 2 mixture) and its afterglow were calculated for the given experimental conditions. Analysis of the experimental data shows that the influence of the nitrogen admixture on the shape of the dependence U b (τ) is, to a large extent, caused by the change in the decay rate of the argon afterglow plasma in the presence of a nitrogen admixture. 相似文献
2.
The characteristics of a glow discharge in Ar:N 2 mixtures with a low content of nitrogen (0.02–1%) are studied experimentally. Most studies were performed at pressures higher than 10 Torr, at which the discharge constriction goes by a jump and the hysteresis effect is well pronounced. It is found that the time during which the discharge switches from the diffuse to the constricted mode (and back) can reach ~1 s. The transition between these modes begins with the development of a constriction at one end of the positive column. Then, the constricted part of the discharge extends toward the other end until it occupies the entire column. The reverse transition occurs in a similar way. By varying the parameters of the electric circuit during the transition, the constriction front can be stopped to form a steady-state partially constricted discharge. It is shown that this type of discharge corresponds to points lying inside the hysteresis loop of the conventional I-V characteristic measured without affecting the discharge during a transition. A comparative analysis of the discharge characteristics in Ar:N 2 mixtures and in pure argon is performed. 相似文献
3.
Experiments with quasi-steady high-current discharges in crossed E × B fields in various gases (Ar, N 2, H 2, and SF 6) and gas mixtures (Ar/SF 6 and Ar/O 2) at pressures from 10 −3 to 5 Torr in discharge systems with different configurations of electric and magnetic fields revealed a specific type of
stable low-voltage discharge that does not transform into an arc. This type of discharge came to be known as a high-current
diffuse discharge and, later, a nonsputtering impulse magnetron discharge. This paper presents results from experimental studies
of the plasma parameters (the electron temperature, the plasma density, and the temperature of ions and atoms of the plasma-forming
gas) of a high-current low-pressure diffuse discharge in crossed E × B fields. 相似文献
4.
A controlled growth chamber experiment was conducted to investigate the short-term water use and photosynthetic responses
of 30-d-old carrot seedlings to the combined effects of CO 2 concentration (50–1 050 μmol mol −1) and moisture deficits (−5, −30, −55, and −70 kPa). The photosynthetic response data was fitted to a non-rectangular hyperbola
model. The estimated parameters were compared for effects of moisture deficit and elevated CO 2 concentration (EC). The carboxylation efficiency (α) increased in response to mild moisture stress (−30 kPa) under EC when
compared to the unstressed control. However, moderate (−55 kPa) and extreme (−70 kPa) moisture deficits reduced α under EC.
Maximum net photosynthetic rate ( P
Nmax) did not differ between mild water deficit and unstressed controls under EC. Moderate and extreme moisture deficits reduced
P
Nmax by nearly 85 % compared to controls. Dark respiration rate ( R
D) showed no consistent response to moisture deficit. The CO 2 compensation concentration (Γ) was 324 μmol mol −1 for −75 kPa and ranged 63–93 μmol mol −1 for other moisture regimes. Interaction between moisture deficit and EC was noticed for P
N, ratio of intercellular and ambient CO 2 concentration ( C
i/ C
a), stomatal conductance ( g
s
), and transpiration rate ( E). P
N was maximum and C
i/ C
a was minimum at −30 kPa moisture deficit and at C
a of 350 μmol mol −1. The g
s and E showed an inverse relationship at all moisture deficit regimes and EC. Water use efficiency (WUE) increased with moisture
deficit up to −55 kPa and declined thereafter. EC showed a positive influence towards sustaining P
N and increasing WUE only under mild moisture stress, and no beneficial effects of EC were noticed at moderate or extreme moisture
deficits. 相似文献
5.
Gross rates of N mineralization and nitrification, and soil–atmosphere fluxes of N 2O, NO and NO 2 were measured at differently grazed and ungrazed steppe grassland sites in the Xilin river catchment, Inner Mongolia, P. R.
China, during the 2004 and 2005 growing season. The experimental sites were a plot ungrazed since 1979 (UG79), a plot ungrazed
since 1999 (UG99), a plot moderately grazed in winter (WG), and an overgrazed plot (OG), all in close vicinity to each other.
Gross rates of N mineralization and nitrification determined at in situ soil moisture and soil temperature conditions were
in a range of 0.5–4.1 mg N kg −1 soil dry weight day −1. In 2005, gross N turnover rates were significantly higher at the UG79 plot than at the UG99 plot, which in turn had significantly
higher gross N turnover rates than the WG and OG plots. The WG and the OG plot were not significantly different in gross ammonification
and in gross nitrification rates. Site differences in SOC content, bulk density and texture could explain only less than 15%
of the observed site differences in gross N turnover rates. N 2O and NO
x
flux rates were very low during both growing seasons. No significant differences in N trace gas fluxes were found between
plots. Mean values of N 2O fluxes varied between 0.39 and 1.60 μg N 2O-N m −2 h −1, equivalent to 0.03–0.14 kg N 2O-N ha −1 y −1, and were considerably lower than previously reported for the same region. NO
x
flux rates ranged between 0.16 and 0.48 μg NO
x
-N m −2 h −1, equivalent to 0.01–0.04 kg NO
x
-N ha −1 y −1, respectively. N 2O fluxes were significantly correlated with soil temperature and soil moisture. The correlations, however, explained only
less than 20% of the flux variance. 相似文献
6.
Excitation of a microwave discharge at the end of a cylindrical electrode in nitrogen at a pressure of 1 Torr and incident
powers of 60–140 W was investigated experimentally by using K-008 and K-011 video cameras and analyzing oscillograms of discharge
emission. The times during which the discharge is established in the radial and axial directions are found to be on the order
of 10 −4 and 10 −2 s, respectively. The results obtained are analyzed using one-dimensional simulations of a discharge in nitrogen in a quasistatic
approximation. The kinetic scheme includes 50 processes involving electrons, ions, and excited molecules and atoms. The time
evolution of the concentrations of molecular nitrogen in the N 2( C
3II
u
) and N 2( B
3II
g
) states, responsible for the recorded discharge emission, is compared with the experimental data. 相似文献
7.
The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O 2 evolution ( J
O2) and net rates of CO 2 uptake ( P
N) were measured in the halotolerant estuarine C 4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments. Under high irradiance, salinity had no significant effect on the intercellular to ambient
CO 2 concentration ratio ( C
i/ C
a). However, during photosynthesis under limiting irradiance, the maximum quantum efficiency of CO 2 fixation decreased under salinity across species, suggesting there is increased leakage of the CO 2 delivered to the bundle sheath cells by the C 4 pump. Growth under salinity did not affect the maximum intrinsic efficiency of photosystem 2, PS2 (F V/F M) in these species, suggesting salinity had no effect on photosynthesis by inactivation of PS2 reaction centers. Under saline
conditions and high irradiance, P
N was reduced by 75 % in Spartina patens and S. alterniflora, whereas salinity had no effect on P
N in S. densiflora or D. spicata. This inhibition of P
N in S. patens and S. alterniflora was not due to an effect on stomatal conductance since the ratio of C
i/ C
a did not decrease under saline conditions. In growth with and without salt, P
N was saturated at ∼500 μmol(quantum) m −2 s −1 while J
O2 continued to increase up to full sunlight, indicating that carbon assimilation was not tightly coupled to photochemistry
in these halophytic species. This increase in alternative electron flow under high irradiance might be an inherent function
in these halophytes for dissipating excess energy. 相似文献
8.
Abstract Potentially bioactive N-(aminoalkyl)lactamic amino acids and esters were synthesized in satisfactory to good yields by S NAr reactions of aromatic acids with N-(3-aminopropyl)lactams followed by esterification with tertiary amino alcohols. The addition–elimination S NAr mechanism was confirmed by NMR and MS measurements. 相似文献
10.
In a combined field and laboratory study in the southwest of Burkina Faso, we quantified soil-atmosphere N 2O and NO exchange. N 2O emissions were measured during two field campaigns throughout the growing seasons 2005 and 2006 at five different experimental
sites, that is, a natural savanna site and four agricultural sites planted with sorghum ( n = 2), cotton and peanut. The agricultural fields were not irrigated and not fertilized. Although N 2O exchange mostly fluctuated between −2 and 8 μg N 2O–N m −2 h −1, peak N 2O emissions of 10–35 μg N 2O–N m −2 h −1 during the second half of June 2005, and up to 150 μg N 2O–N m −2 h −1 at the onset of the rainy season 2006, were observed at the native savanna site, whereas the effect of the first rain event
on N 2O emissions at the crop sites was low or even not detectable. Additionally, a fertilizer experiment was conducted at a sorghum
field that was divided into three plots receiving different amounts of N fertilizer (plot A: 140 kg N ha −1; plot B: 52.5 kg N ha −1; plot C: control). During the first 3 weeks after fertilization, only a minor increase in N 2O emissions at the two fertilized plots was detected. After 24 days, however, N 2O emission rates increased exponentially at plot A up to a mean of 80 μg N 2O–N m −2 h −1, whereas daily mean values at plot B reached only 19 μg N 2O–N m −2 h −1, whereas N 2O flux rates at plot C remained unchanged. The calculated annual N 2O emission of the nature reserve site amounted to 0.52 kg N 2O–N ha −1 a −1 in 2005 and to 0.67 kg N 2O–N ha −1 a −1 in 2006, whereas the calculated average annual N 2O release of the crop sites was only 0.19 kg N 2O–N ha −1 a −1 and 0.20 kg N 2O–N ha −1 a −1 in 2005 and 2006, respectively. In a laboratory study, potential N 2O and NO formation under different soil moisture regimes were determined. Single wetting of dry soil to medium soil water
content with subsequent drying caused the highest increase in N 2O and NO emissions with maximum fluxes occurring 1 day after wetting. The stimulating effect lasted for 3–4 days. A weaker
stimulation of N 2O and NO fluxes was detected during daily wetting of soil to medium water content, whereas no significant stimulating effect
of single or daily wetting to high soil water content (>67% WHC max) was observed. This study demonstrates that the impact of land-use change in West African savanna on N trace gas emissions
is smaller—with the caveat that there could have been potentially higher N 2O and NO emissions during the initial conversion—than the effect of timing and distribution of rainfall and of the likely
increase in nitrogen fertilization in the future. 相似文献
11.
In sunflower ( Helianthus annuus L.) grown under controlled conditions and subjected to drought by withholding watering, net photosynthetic rate ( P
N) and stomatal conductance ( g
s) of attached leaves decreased as leaf water potential (Ψ w) declined from −0.3 to −2.9 MPa. Although g
s decreased over the whole range of Ψ w, nearly constant values in the intercellular CO 2 concentrations ( C
i) were observed as Ψ w decreased to −1.8 MPa, but C
i increased as Ψ w decreased further. Relative quantum yield, photochemical quenching, and the apparent quantum yield of photosynthesis decreased
with water deficit, whereas non-photochemical quenching (q NP) increased progressively. A highly significant negative relationship between q NP and ATP content was observed. Water deficit did not alter the pyridine nucleotide concentration but decreased ATP content
suggesting metabolic impairment. At a photon flux density of 550 μmol m −2 s −1, the allocation of electrons from photosystem (PS) 2 to O 2 reduction was increased by 51 %, while the allocation to CO 2 assimilation was diminished by 32 %, as Ψ w declined from −0.3 to −2.9 MPa. A significant linear relationship between mean P
N and the rate of total linear electron transport was observed in well watered plants, the correlation becoming curvilinear
when water deficit increased. The maximum quantum yield of PS2 was not affected by water deficit, whereas q P declined only at very severe stress and the excess photon energy was dissipated by increasing q NP indicating that a greater proportion of the energy was thermally dissipated. This accounted for the apparent down-regulation
of PS2 and supported the protective role of q NP against photoinhibition in sunflower. 相似文献
12.
ET A subtype selective antagonists constitute a novel and potentially important class of agents for the treatment of pulmonary
hypertension, heart failure, and other pathological conditions. In this paper, 60 benzodiazepine derivatives displaying potent
activities against ET A and ET B subtypes of endothelin receptor were selected to establish the 3D-QSAR models using CoMFA and CoMSIA approaches. These models
show excellent internal predictability and consistency, external validation using test-set 19 compounds yields a good predictive
power for antagonistic potency. Statistical parameters of models were obtained with CoMFA-ET A ( q
2 = 0.787, r
2 = 0.935, r
2
pred
= 0.901), CoMFA-ET B ( q
2 = 0.842, r
2 = 0.984, r
2
pred
= 0.941), CoMSIA-ET A ( q
2 = 0.762, r
2 = 0.971, r
2
pred
= 0.958) and CoMSIA-ET B ( q
2 = 0.771, r
2 = 0.974, r
2
pred
= 0.953) respectively. Field contour maps (CoMFA and CoMSIA) corresponding to the ET A and ET B subtypes reflects the characteristic similarities and differences between these types. The results of this paper provide
valuable information to facilitate structural modifications of the title compounds to increase the inhibitory potency and
subtype selectivity of endothelin receptor. 相似文献
13.
Cultivating dinitrogen-fixing legume trees with crops in agroforestry is a relatively common N management practice in the
Neotropics. The objective of this study was to assess the N 2 fixation potential of three important Neotropical agroforestry tree species, Erythrina poeppigiana, Erythrina fusca, and Inga edulis, under semi-controlled field conditions. The study was conducted in the humid tropical climate of the Caribbean coastal plain
of Costa Rica. In 2002, seedlings of I. edulis and Vochysia guatemalensis were planted in one-meter-deep open-ended plastic cylinders buried in soil within hedgerows of the same species. Overall
tree spacing was 1 × 4 m to simulate a typical alley-cropping design. The 15N was applied as (NH 4) 2SO 4 at 10% 15N atom excess 15 days after planting at the rate of 20 kg [N] ha −1. In 2003, seedlings of E. poeppigiana, E. fusca, and V. guatemalensis were planted in the same field using the existing cylinders. The 15N application was repeated at the rate of 20 kg [N] ha −1 15 days after planting and 10 kg [N] ha −1 was added three months after planting. Trees were harvested 9 months after planting in both years. The 15N content of leaves, branches, stems, and roots was determined by mass spectrometry. The percentage of atmospheric N fixed
out of total N (%N f) was calculated based on 15N atom excess in leaves or total biomass. The difference between the two calculation methods was insignificant for all species.
Sixty percent of I. edulis trees fixed N 2; %N f was 57% for the N 2-fixing trees. Biomass production and N yield were similar in N 2-fixing and non-N 2-fixing I. edulis. No obvious cause was found for why not all I. edulis trees fixed N 2. All E. poeppigiana and E. fusca trees fixed N 2; %N f was ca. 59% and 64%, respectively. These data were extrapolated to typical agroforestry systems using published data on N recycling
by the studied species. Inga edulis may recycle ca. 100 kg ha −1 a −1 of N fixed from atmosphere to soil if only 60% of trees fix N 2, E. poeppigiana 60–160 kg ha −1 a −1, and E. fusca
ca. 80 kg ha −1 a −1. 相似文献
14.
The aim of this research was to test whether NH 4
+ and NO 3
− affect the growth, P demand, cell composition and N 2 fixation of Cylindrospermopsis raciborskii under P limitation. Experiments were carried out in P-limited (200 μg l −1 PO 4-P) chemostat cultures of C. raciborskii using an inflowing medium containing either 4,000 μg l −1 NH 4-N, 4,000 μg l −1 NO 3-N or no combined N. The results showed the cellular N:P and C:P ratios of C. raciborskii decreased towards the Redfield ratio with increasing dilution rate ( D) due to the alleviation of P limitation. The cellular C:N and carotenoids:chlorophyll- a ratios also decreased with D, predominantly as a result of an increase in the chlorophyll- a and N content. The NH 4
+ and NO 3
− supply reduced the P maintenance cell quota of C. raciborskii. Consequently, the biomass yield of the N 2-grown culture was significantly lower. The maximum specific growth rate of N 2-grown culture was also the lowest observed. It is suggested that these differences in growth parameters were caused by the
P and energy requirement for heterocyte formation, nitrogenase synthesis and N 2 fixation. N 2 fixation was partially inhibited by NO 3
− and completely inhibited by NH 4
+. It was probably repressed through the high N content of cells at high dissolved N concentrations. These results indicate
that C. raciborskii is able to grow faster and maintain a higher biomass under P limitation where a sufficient supply of NH 4
+ or NO 3
− is maintained. Information gained about the species-specific nutrient and pigment stoichiometry of C. raciborskii could help to access the degree of nutrient limitation in water bodies.
Handling editor: Luigi Naselli-Flores 相似文献
15.
N-nitrosamine is a class of carcinogenic, mutagenic, and teratogenic compounds, which can be produced from N-nitrosation of amine by nitrosating agents. N-nitrosation of 19 amines (eight acyclic amines, five heterocyclic amines, and six amines with unsaturated groups) by N 2O 3 was investigated at the CBS-QB3 level of theory. The results indicate that generally the heterocyclic amines have the highest
reactivities among the three kinds of amines, whereas the reactivities of the amines with unsaturated and electron-withdrawing
groups are relatively low. Frontier molecular orbital analysis indicates that the energy gap between the HOMO of an amine
and the LUMO of N 2O 3 has a close connection with the reactivity of an amine. A structure-reactivity relationship of amines in the N-nitrosation reactions by N 2O 3 was established using the stepwise multivariate linear regression. The results indicate that the reactivity of an amine has
a definite relationship (R adj2 = 0.947) with the heterolytic bond dissociation energy of R 1R 2N-H bond, energy of HOMO, NBO occupancy of the natural lone pair orbital of N atom, the NBO charge of the N atom, and the
pyramidalization angle of an amine. This work will be helpful to gain more insight into the N-nitrosation reactions. 相似文献
16.
Two cultivars (Katy and Erhuacao) of apricot ( Prunus armeniaca L.) were evaluated under open-field and solar-heated greenhouse conditions in northwest China, to determine the effect of
photosynthetic photon flux density (PPFD), leaf temperature, and CO 2 concentration on the net photosynthetic rate ( P
N). In greenhouse, Katy registered 28.3 μmol m −2 s −1 for compensation irradiance and 823 μmol m −2 s −1 for saturation irradiance, which were 73 and 117 % of those required by Erhuacao, respectively. The optimum temperatures
for cvs. Katy and Erhuacao were 25 and 35 °C in open-field and 22 and 30 °C in greenhouse, respectively. At optimal temperatures,
P
N of the field-grown Katy was 16.5 μmol m −2 s −1, 21 % less than for a greenhouse-grown apricot. Both cultivars responded positively to CO 2 concentrations below the CO 2 saturation concentration, whereas Katy exhibited greater P
N (18 %) and higher carboxylation efficiency (91 %) than Erhuacao at optimal CO 2 concentration. Both cultivars exhibited greater photosynthesis in solar-heated greenhouses than in open-field, but Katy performed
better than Erhuacao under greenhouse conditions. 相似文献
17.
This work aimed to evaluate if gas exchange and PSII photochemical activity in maize are affected by different irradiance
levels during short-term exposure to elevated CO 2. For this purpose gas exchange and chlorophyll a fluorescence were measured on maize plants grown at ambient CO 2 concentration (control CO 2) and exposed for 4 h to short-term treatments at 800 μmol(CO 2) mol −1 (high CO 2) at a photosynthetic photon flux density (PPFD) of either 1,000 μmol m −2 s −1 (control light) or 1,900 μmol m −2 s −1 (high light). At control light, high-CO 2 leaves showed a significant decrease of net photosynthetic rate ( P
N) and a rise in the ratio of intercellular to ambient CO 2 concentration ( C
i/ C
a) and water-use efficiency (WUE) compared to control CO 2 leaves. No difference between CO 2 concentrations for PSII effective photochemistry (Φ PSII), photochemical quenching (q p) and nonphotochemical quenching (NPQ) was detected. Under high light, high-CO 2 leaves did not differ in P
N, C
i/ C
a, Φ PSII and NPQ, but showed an increase of WUE. These results suggest that at control light photosynthetic apparatus is negatively
affected by high CO 2 concentration in terms of carbon gain by limitations in photosynthetic dark reaction rather than in photochemistry. At high
light, the elevated CO 2 concentration did not promote an increase of photosynthesis and photochemistry but only an improvement of water balance due
to increased WUE. 相似文献
18.
Enterococcus hirae grow well under anaerobic conditions at alkaline pH (pH 8.0) producing acids by glucose fermentation. Bacterial growth was
shown to be accompanied by decrease of redox potential from positive values (~+35 mV) to negative ones (~−220 mV). An oxidizer
copper (II) ions (Cu 2+) affected bacterial growth in a concentration-dependent manner (within the range of 0.05 mM to 1 mM) increasing lag phase
duration and decreasing specific growth rate. These effects were observed with the wild-type strain ATCC9790 and the atpD mutant strain MS116 (with absent β subunit of F 1 of the F oF 1 ATPase) both. Also ATPase activity and proton–potassium ions exchange were assessed with and without N, N′-dicyclohexylcarbodiimide (DCCD), inhibitor of the F oF 1 ATPase. In both cases (DCCD ±), even low Cu 2+ concentrations had noticeable effect on ATPase activity, but with less visible concentration-dependent manner. Changes in
the number of accessible SH-groups were observed with E. hirae ATCC9790 and MS116 membrane vesicles. In both strains Cu 2+ markedly decreased the number of SH-groups in the presence of K + ions. The addition of ATP increased the amount of accessible SH-groups in ATCC9790 and decreased this number in MS116; Cu 2+ blocked ATP-installed increase in SH-groups number in ATCC9790. H +–K +-exchange of bacteria was markedly inhibited by Cu 2+, but stronger effects were detected together with DCCD. Moreover, discrimination between Cu 2+ and other bivalent cation—Ni 2+ was shown. It is suggested that Cu 2+ ions inhibit E. hirae cell growth by direct affect on the F oF 1 ATPase leading to conformational changes in this protein complex and decrease in its activity. 相似文献
19.
Adenosine is known to exert most of its physiological functions by acting as local modulator at four receptor subtypes named
A 1, A 2A, A 2B and A 3 (ARs). Principally as a result of the difficulty in identifying potent and selective agonists, the A 2B AR is the least extensively characterised of the adenosine receptors family. Despite these limitations, growing understanding
of the physiological meaning of this target indicates promising therapeutic perspectives for specific ligands. As A 2B AR signalling seems to be associated with pre/postconditioning cardioprotective and anti-inflammatory mechanisms, selective
agonists may represent a new therapeutic group for patients suffering from coronary artery disease. Herein we present an overview
of the recent advancements in identifying potent and selective A 2B AR agonists reported in scientific and patent literature. These compounds can be classified into adenosine-like and nonadenosine
ligands. Nucleoside-based agonists are the result of modifying adenosine by substitution at the N
6-, C 2-positions of the purine heterocycle and/or at the 5′-position of the ribose moiety or combinations of these substitutions.
Compounds 1-deoxy-1-{6-[ N′-(furan-2-carbonyl)-hydrazino]-9 H-purin-9-yl}-N-ethyl- β-D-ribofuranuronamide ( 19, hA 1
K
i = 1050 nM, hA 2A
K
i = 1550 nM, hA 2B EC 50 = 82 nM, hA 3
K
i > 5 μM) and its 2-chloro analogue 23 (hA 1
K
i = 3500 nM, hA 2A
K
i = 4950 nM, hA 2B EC 50 = 210 nM, hA 3
K
i > 5 μM) were confirmed to be potent and selective full agonists in a cyclic adenosine monophosphate (cAMP) functional assay
in Chinese hamster ovary (CHO) cells expressing hA 2B AR. Nonribose ligands are represented by conveniently substituted dicarbonitrilepyridines, among which 2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]pyridin-2-ylsulfanyl]acetamide
( BAY-60–6583, hA 1, hA 2A, hA 3 EC 50 > 10 μM; hA 2B EC 50 = 3 nM) is currently under preclinical-phase investigation for treating coronary artery disorders and atherosclerosis. 相似文献
20.
The optical and electrical characteristics of pulsed discharges in pure Ar at pressures of up to 7 atm, at which the discharge becomes unstable, are studied in a simple experimental device with automatic preionization. The gas temperature in the discharge is estimated from the width of the recorded emission spectrum. An analytical model of the vibrational relaxation of Ar
*2
(v) is used to better determine the constants of the vibrational-translational relaxation of Ar
*2
(v) molecules in their collisions with Ar atoms. The zerodimensional numerical model of a pulsed discharge in Ar is modified. The experimental and calculated results are compared in detail. Good agreement is achieved between the measured and calculated time dependences of the electrode voltage and the intensity of spontaneous emission in the pressure range of 1–6 atm, as well as between the measured and calculated values of the gas temperature at pressures of 3–6 atm. Preliminary results from numerical studies of the possibility of achieving generation are discussed. 相似文献
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