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1.
The distribution of valency electron density in Cu2As (C38) has been determined by Fourier synthesis using as coefficients the values ΔF = Fobs ? Fcore (Fcore corresponds to the structure factors of the inner orbitals). The bonding between the pyramidal-site copper atoms and the arsenic atoms is exposed, as well as the bonding between tetrahedral-site and pyramidal-site copper atoms.The structural evolution of the unit cell from the Cu2Sb-type (C38) to the Fe2P-type (C22) and Co2P-type (C23) can be related to the metal-metalloid interaction. This interaction mainly involves the pyramidal-site metal atoms in the Cu2Sb-type, and the tetrahedral-site metal atoms in the Fe2P- and Co2P-types. 相似文献
2.
W. J. Naudé M. Peisach R. Pretorius P. J. Strebel 《Journal of Radioanalytical and Nuclear Chemistry》1968,1(3):231-241
Carbon, nitrogen and oxygen were determined in gases by time-of-flight spectrometry of prompt neutrons from the respective
reactions12C(d, n)13N,14N(d, n)15O and16O(d, n)17F, produced by a pulsed beam of deuterons of 2 MeV (for nitrogen) or 3 MeV. The analysis is non-destructive and requires about
15 min. per sample. The relative standard deviation for all three elements was about ±3%. Detection limits, using a total
irradiation current of 20 millicoulombs, for carbon, nitrogen and oxygen, respectively, were 6·10−8 g, 2·10−7 g and 1.7·10−7 g per cm2 cross-sectional area of irradiating beam. 相似文献
3.
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An HPLC‐ECD method for monoamines and metabolites quantification in cuttlefish (cephalopod) brain tissue 下载免费PDF全文
Flavie Bidel Sophie Corvaisier Christelle Jozet‐Alves Ivannah Pottier François Dauphin Nadège Naud Cécile Bellanger 《Biomedical chromatography : BMC》2016,30(8):1175-1183
The cuttlefish belongs to the mollusk class Cephalopoda, considered as the most advanced marine invertebrates and thus widely used as models to study the biology of complex behaviors and cognition, as well as their related neurochemical mechanisms. Surprisingly, methods to quantify the biogenic monoamines and their metabolites in cuttlefish brain remain sparse and measure a limited number of analytes. This work aims to validate an HPLC‐ECD method for the simultaneous quantification of dopamine, serotonin, norepinephrine and their main metabolites in cuttlefish brain. In comparison and in order to develop a method suitable to answer both ecological and biomedical questions, the validation was also carried out on a phylogenetically remote species: mouse (mammals). The method was shown to be accurate, precise, selective, repeatable and sensitive over a wide range of concentrations for 5‐hydroxyindole‐3‐acetic acid, serotonin, dopamine, 3,4‐dihydroxyphenylacetic acid and norepinephrine in the both extracts of cuttlefish and mouse brain, though with low precision and recovery for 4‐hydroxy‐3‐methoxyphenylethylene glycol. Homovanillic acid, accurately studied in rodents, was not detectable in the brain of cuttlefish. Overall, we described here the first fully validated HPLC method for the routine measurement of both monoamines and metabolites in cuttlefish brain. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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6.
Background
Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH. 相似文献7.
J. J. Lawrie W. J. Naudé J. A. Stander J. W. Koen N. J. A. Rust 《Zeitschrift für Physik A Hadrons and Nuclei》1986,323(4):375-385
Properties of levels up to 5 MeV excitation in37Cl were studied with37Cl(p, p′ γ)37Cl,37Cl(α, α′ γ)37Cl and34S(α, pγ)37Cl reactions. Results are discussed with reference to the many-particle shell model with an effective surface delta interaction. 相似文献
8.
J. A. Stander W. J. Naudé R. Saayman N. J. A. Rust 《Zeitschrift für Physik A Hadrons and Nuclei》1986,323(1):47-57
The spins and electromagnetic properties of low-lying levels in39K with excitation energy ≦4.127 MeV were studied with the39K(p, p′γ)39K and the36Ar(α, pγ)39K reactions. Experimental results are discussed in terms of shell model calculations with a modified effective surface delta interaction. 相似文献
9.
Numerical simulation results are presented for three turbulent jet diffusion flames, stabilized behind a bluff body (Sydney
Flames HM1-3). Interaction between turbulence and combustion is modeled with the transported joint-scalar PDF approach. The
focus of the study is on the impact of the quality of simulation results in physical space on the behavior of two micro-mixing
models in composition space: the Euclidean Minimum Spanning Tree (‘EMST’) model and the modified Curl coalescence dispersion
(‘CD’) model. Profiles of conditional means and variances of thermo-chemical quantities, conditioned on the mixture fraction,
are discussed in the recirculation region and in the neck zone behind. The impact of the flow and mixing fields in physical
space on the mixing model behavior in composition space is strong for the CD model and increases as the turbulence – chemistry
interaction becomes stronger. The EMST conditional profiles, on the contrary, are hardly affected. 相似文献
10.
Numerical Investigation of a Bluff-Body Stabilised Nonpremixed Flame with Differential Reynolds-Stress Models 总被引:1,自引:0,他引:1
A numerical investigation of a bluff-body stabilised nonpremixedflame, and the corresponding nonreacting flow, has been performed withdifferential Reynolds-stress models (DRSMs). The equilibrium chemistry model is employed and an assumed-shape beta function PDFapproach is used to represent the interaction between turbulence andchemistry. The Reynolds flux of the mixture fraction is obtained from atransport equation, hence a full second moment closure is used. Toclarify the applicability of the existing DRSMs in this complex flame,several models, including LRR-IP model, JM model, SSG model as well as amodified LRR-IP model, have been applied and evaluated. The existingmodels, with default values of the coefficients, cannot provide overallsatisfactory predictions for this challenging test case. The standardLRR-IP model over predicts the centreline velocity decay rate, andtherefore does not perform satisfactory. The modified LRR-IP model, withmodel constant C ∈1 = 1.6 instead of the standard value1.44 (here named BM-M1), gives better results for the mean velocity.However in the nonreacting case this does not lead to improvement inpredicting rms fluctuating velocities especially downstream of therecirculation zone. Motivated by the need to improve the prediction, anew modification of the LRR-IP model is proposed (BM-M2), with modelconstant C 2 = 0.7in the pressure strain correlation rather thanthe standard value 0.6. With the new modified model, a verysignificant improvement of the prediction of flow field is obtained inthe nonreacting case, whereas in the reacting case the prediction ofthe flow field is of the same overall quality as with BM-M1. This showsthat some DRSMs have different behaviour in the nonreacting case andthe reacting case. In the reacting case also the mean and variance ofmixture fraction are considered and it is found that the best resultsare obtained with the BM-M1 model, with SSG as second best. Combiningthe results for flow field and mixture fraction field it is concludedthat the BM-M1 model is recommended for further studies of thisbluff-body stabilised flame. Grid independence of the result isdemonstrated. 相似文献