共查询到20条相似文献,搜索用时 46 毫秒
1.
V. N. Odinokov R. V. Shafikov R. G. Savchenko S. R. Afon’kina I. V. Galyautdinov L. M. Khalilov A. S. Shashkov 《Russian Journal of Organic Chemistry》2008,44(5):671-674
By hydrogenation of (20R,22R)-6α,14α,25-trihydroxy-and (20R,22R)-6β,14α,25-trihydroxy-2,3:20,22-bis(isopropylidenedioxy)-5α-cholest-7-enes on a catalyst (Raney nickel) the corresponding (5α,6α)-and (5β,6β)-epimers of previously unknown Δ8,14-6-hydroxy derivatives of ecdysteroids were synthesized. 相似文献
2.
Kaolinite clay obtained from Ubulu-Ukwu, Delta state in Nigeria was modified with polyvinyl alcohol (PVA) reagent to obtain
PVA-modified Kaolinite clay adsorbent. Scanning Electron Microscopy (SEM) of the PVA-modified adsorbent suggests that Kaolinite
clay particles were made more compact in nature with no definite structure. Modification of Kaolinite clay with PVA increased
its adsorption capacity for 300 mg/L Pb2+ and Cd2+ by a factor of at least 6, i.e., from 4.5 mg/g to 36.23 mg/g and from 4.38 mg/g to 29.85 mg/g, respectively, at 298 K. Binary
mixtures of Pb2+ and Cd2+ decreased the adsorption capacity of Unmodified Kaolinite clay for Pb2+ by 26.3% and for Cd2+ by 0.07%, respectively. In contrast, for PVA-modified Kaolinite clay, the reductions were up to 50.9% and 58.5% for Pb2+ and Cd2+, respectively.
The adsorption data of Pb2+ and Cd2+ onto both Unmodified and PVA-modified Kaolinite clay adsorbents were found to fit the Pseudo-Second Order Kinetic model (PSOM),
indicating that adsorption on both surfaces was mainly by chemisorption and is concentration dependent. However, kinetic adsorption
data from both adsorbent generally failed the Pseudo-First order Kinetic model (PFOM) test.
Extents of desorption of 91% Pb2+ and 94% Cd2+ were obtained, using 0.1 M HCl, for the Unmodified Kaolinite clay adsorbent. It was found that 99% Pb2+ and 97% Cd2+, were desorbed, for PVA-modified Kaolinite clay adsorbents within 3 min for 60 mg/L of the metal ions adsorbed by the adsorbents. 相似文献
3.
The equilibria AuCl4−+jOH−+kH2O⇌AuCl4−j−k
(OH)
j
(H2O)
k
k−1+(j+k)Cl−, β
jk
(0≤j,k≤4) have been studied spectrophotometrically at 20 °C in aqueous solution. For I=2 mol⋅dm−3(HClO4) the conventional constants, β
i
*, of the equilibria, Au*+iCl−
⇌AuCl
i
*, are equal to log 10
β
1*=(6.98±0.08); log 10
β
2*=(13.42±0.05); log 10
β
3*=(19.19±0.09); and log 10
β
4*=(24.49±0.07), where [AuCl
i
*]=∑[AuCl
i
(OH)
j
(H2O)4−i−j
] at i=const. The hydrolysis and other transformations of AuCl4− in aqueous solution are discussed. On the basis of new and known data, a full set of equilibrium constants, β
jk
, or their estimates has been obtained. 相似文献
4.
Abstract The title compound, labeled with 13C in the ethyl groups was synthesized from K13CN and low-molecular-weight components. The synthetic relay compound was 31(32)[13C]-xanthobilirubinic acid methyl ester in a synthetic route that leads to a label in the ethyl β-substituent of a dipyrrinone
model for bilirubin. This labeled dipyrrinone was oxidatively coupled to the dimethyl ester of mesobiliverdin-XIIIα, thereby
providing a route to a 13C-labeled mesobiliverdin and mesobilirubin, with one carbon of each ethyl being 98% 13C-enriched.
Graphical Abstract
相似文献
5.
Junhua Luo Fei Tuo Xiangzhong Kong 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):143-148
The cross sections for formation of metastable state of 178Hf (178m2Hf, 574.215 keV, 31 y) and 179Hf (179m2Hf, 362.55 keV, 25.05 d) through reactions induced by 14.8 ± 0.2 MeV neutrons on natural hafnium were measured for the first
time. The monoenergetic neutron beam was produced via the 3H(d, n)4He reaction on ZF-300-II Intense Neutron Generator at Lanzhou University. Induced gamma activities were measured by a gamma-ray
spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence
(pile-up), dead time and fluctuation of neutron flux. The neutron fluence were determined by the cross section of 93Nb(n, 2n)92mNb reaction. The neutron energy in the measurement were by the cross section ratios of 90Zr(n, 2n)89m+gZr and 93Nb(n, 2n)92mNb reactions. 相似文献
6.
G. L. Sharipov A. A. Tukhbatullin P. V. Kovyazin L. V. Parfenova P. V. Ivchenko I. E. Nifant’ev 《Russian Chemical Bulletin》2015,64(12):2776-2779
This work describes a comparative study of tribo- and photoluminescence of metallocenes (Cp2HfCl2, Cp2TiCl2, Cp2ZrCl2, (CpMe)2ZrCl2, rac-Me2C(3-But-Cp)2ZrCl2, Ind*2ZrCl2). Occurring under mechanodestruction of polycrystals, triboluminescence of zirconium bis-cyclopentadienyl complexes, Cp2ZrCl2, (CpMe)2ZrCl2, and rac-Me2C(3-But-Cp)2ZrCl2 has been revealed for the first time. The triboluminescence spectrum in air is similar to the photoluminescence spectrum of zirconocene polycrystals. The triboluminescence spectrum does not show *N2 luminescence. Ne and Ar lines are observed in the triboluminescence spectrum in the atmosphere of these gases. An increase in the number of substituents in zirconocene ligands leads to a bathochromic shift of the emission band maximum in triboluminescence spectra of the complexes. Possible mechanisms of zirconocene triboluminescence excitation are discussed. 相似文献
7.
Ayagoz Baimukhanova Valery Radchenko Ján Kozempel Atanaska Marinova Victoria Brown Vasily Karandashev Dimitr Karaivanov Paul Schaffer Dmitry Filosofov 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):191-199
Utilization of (p, 4n) reaction channel for the production of medical radionuclides became very attractive with commercial availability of medium energy cyclotrons. Significantly higher yields and radionuclidic purity may open new perspectives for several novel and some of the radionuclides previously have not been considered due to production difficulties. In present work, we show the proof-of-principle study on the production of 86Y for Positron Emission Tomography imaging via radionuclide generator 86Zr → 86Y. Production suitability of 86Zr from natural yttrium target and radiochemical separation strategies were tested. In addition, two generator systems were proposed and evaluated. 相似文献
8.
N. M. Antovic N. Svrkota I. Antovic 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):313-318
A coincidence method for measuring radium and thorium activity has been developed using the PRIPYAT-2M gamma-ray coincidence
spectrometer, with six NaI(Tl) detectors and registration geometry close to 4π. It was tested by measuring soil samples from
the Northern region of Montenegro, as well as vegetation samples from the same region. The results showed a good agreement
with ones obtained by the HPGe spectrometer. 相似文献
9.
As part of a mass spectrometric investigation of the binding properties of sulfonamide anion receptors, an atmospheric pressure
chemical ionization mass spectrometric (APCI-MS) method involving direct infusion followed by thermal desorption was employed
for identification of anionic supramolecular complexes in dichloromethane (CH2Cl2). Specifically, the dansylamide derivative of tris(2-aminoethyl)amine (tren) (1), the chiral 1,3-benzenesulfonamide derivatives of (1R,2S)-(+)-cis-1-amino-2-indanol (2), and (R)-(+)-bornylamine, (3), were shown to bind halide and nitrate ions in the presence of (n−Bu)4N+X− (X− = Cl−, NO3−, Br−, I−). Solutions of receptors and anions in CH2Cl2 were combined to form the anionic supramolecular complexes, which were subsequently introduced into the mass spectrometer
via direct infusion followed by thermal desorption. The anionic supramolecular complexes [M+X]−, (M=1–3, X−=Cl−, NO3−, Br−, I−) were observed in negative mode APCI-MS along with the deprotonated receptors [M−H]−. Full ionization energy of the APCI corona pin (4.5 kV) was necessary for obtaining mass spectra with the best signal-to-noise
ratios. 相似文献
10.
Martin E. Keillor Matthew W. Cooper James C. Hayes Justin I. McIntyre 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):699-702
Pacific Northwest National Laboratory uses beta-gamma coincidence detectors in a number of xenon sampling and measurement
systems to enable simultaneous, sensitive measurements of 131Xe, 133Xe, 133mXe, and 135Xe for treaty monitoring applications. In recent years, a new style of beta–gamma detector was developed to improve upon the
detector module used in the Automated Radioxenon Sampler/Analyzer. The results of an MCNP5 Monte Carlo simulation of the new
detector cell are presented, with particular emphasis on the identification of an energy deposition sequence with the potential
to introduce significant error into the detector efficiency calibration. This sequence occurs when an 81 keV gamma from 133Xe is absorbed in an inactive region of the CsI(Na) scintillator, followed by emission of a 31 keV X-ray from cesium (or possibly
a 28.5 keV X-ray from iodine). These X-rays add excess counts into the 31 keV peak observed in the decay of 133Xe. The impact of this effect on different efficiency calibration techniques is discussed. 相似文献
11.
Potential energy curves of NgH+ cations (Ng = Kr, Xe, Rn) were obtained by using four-component relativistic CCSD(T) coupled cluster calculations. Dissociation
energies, equilibrium bond lengths, electronic properties, such as dipole moments and electric field gradients at the nuclei,
and the related spectroscopic parameters of the electronic ground state have been determined. The results obtained for KrH+ and XeH+ are in good agreement with available experimental data, while those for RnH+ have been determined for the first time at this level of theory. 相似文献
12.
F. Szelecsényi G. F. Steyn Z. Kovács K. Aardaneh C. Vermeulen T. N. van der Walt 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(1):261-263
Experimentally measured cross-sections are presented for the first time for the 192Os(p,α3n)186Re nuclear reaction up to 67 MeV. Highly enriched thin 192Os targets (15 pcs), prepared by electro-deposition onto Cu backings, were irradiated with an external proton beam delivered
by the SSC cyclotron of iThemba LABS. The excitation function curve of the 192Os(p,α3n)186Re reaction shows a maximum cross-section of ~82 mb at about 24 MeV. According to the yield calculations based on the present
results, the available cumulative no-carrier-added 186Re yield is 7.76 MBq/μAh (0.21 mCi/μAh) over the energy region 13.4 → 27.3 MeV. 相似文献
13.
Cyclotron production of <Superscript>211</Superscript>At/<Superscript>211g</Superscript>Po by <Superscript>209</Superscript>Bi(α,2n) reaction 总被引:1,自引:1,他引:0
S. Morzenti M. L. Bonardi F. Groppi C. Zona E. Persico E. Menapace Z. B. Alfassi 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):843-847
Astatine-211 (T
1/2 = 7.214 h) is an α-emitter at secular equilibrium by EC with its ultra-short-lived α-emitting daughter, polonium-211g (T
1/2 = 0.516 s), with a high Linear Energy Transfer (LET — 130 eV·nm−1) and a half-life suitable for metabolic radiotherapy; the overall α branching of the 211At/211gPo system is 100%. The direct production of 209Bi(α,2n)211At/211gPo seems the most satisfactory method; Bi targets were irradiated at JRC-Ispra Cyclotron of European Commission, EC, using
α-energy higher than 28.61 MeV in order to produce, via 209Bi(α,3n) reaction, small amounts of the γ-emitter 210At (used as internal spike). 相似文献
14.
Degradation of urea in 8 mol·L?1 aqueous solution (20% w/w N) has been studied at 298.15?±?0.01 K over a time period of 150 days. The data were obtained by periodicaly measuring the electric conductivity, acidity, and concentrations of the main species of the solution, such as cyanate, ammonim carbonate and ammonium hydrogencarbonate. The concentration of un-ionized ammonia was calculated on the basis of the data for the total ammonia content in the solution. 相似文献
15.
Mukesh Kumar Pankaj Kumar Anshu Agrawal Rajesh Kumar B. K. Sahoo 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(1):39-45
A novel ethylene diamine tetraacetic acid derivative of 4-nitroimidazole (EDTA-4-EtNHNM) was successfully synthesized as a carrier molecule and it was radiolabeled with 99mTc in high yield to obtain 99mTc-EDTA-4-EtNHNM, which was hydrophilic and had good in vitro stability. The tumor cell experiment and the biodistribution study in mice bearing S180 tumor showed that this complex exhibited a hypoxic selectivity and had high accumulation in tumor tissue with major clearance through urinary tract. High tumor uptake and tumor/muscle ratio of the complex suggests promise towards further evaluation. 相似文献
16.
The mechanism of formation of the electronically excited radical OH*(A2Σ+) has been studied by analyzing calculations quantitatively describing the results of shock wave experiments carried out in order to determine the moment of maximum OH* radiation at temperatures T < 1500 K and pressures P ≤ 2 atm in the H2 + O2 mixtures diluted by argon when the vibrational nonequilibrium is a factor determining the mechanism and rate of the overall process. In kinetic calculations, the vibrational nonequilibrium of the initial H2 and O2 components, the HO2, OH(X2Π), O2*(1Δ) intermediates, and the reaction product H2O were taken into account. The analysis showed that under these conditions the main contribution to the overall process of OH* formation is caused by the reactions OH + Ar → OH* + Ar, H2 + HO2 → OH* + H2O, H2 + O*(1D) → OH* + H, HO2 + O → OH* + O2 and H + H2O → OH* + H2, which occur in the vibrational nonequilibrium mode (their activation barrier is overcome due to the vibrational excitation of reactants), and by H + O3 → OH* + O2 and H + H2O2 → OH* + H2O, which are reverse to the reactions of chemical quenching. 相似文献
17.
Hui-Jun Won Byambatseren Baigalmaa Jei-Kwon Moon Chong-Hun Jung Kune-Woo Lee Jae-Hyuk Hyun 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):525-531
Type 304 stainless steel specimens artificially contaminated with CsCl solution were treated with KOH solution and KNO3 solution, respectively. Cs+ ion removal tests by a Q-switched Nd:YAG laser at 1064 nm at a given fluence of 57.3 J/cm2 were performed. The surface morphology and the relative atomic mole ratio of the specimen surface were investigated by SEM
and EPMA. The order of Cs+ ion removal efficiency of laser was no-treatment < KOH < KNO3 during the 42 shots. From the investigation of XPS peaks around 532.7 and 292.9 eV, KNO3 on a surface of specimen was found to be fully decomposed during the laser irradiation. It was suggested that Cs2O particulates formed by the reaction between the reactive oxygen generated from the nitrate ion and Cs+ ion on the metal surface could be easily suspended. For the KOH system, FeOOH was formed during the laser irradiation and
it changed into Fe2O3. It was also suggested that Cs2O particulates were formed by the reaction between the reactive oxygen generated from the decomposition of K2O and Cs+ ion on the metal surface.. 相似文献
18.
Patrícia Severino Samantha C. Pinho Eliana B. Souto Maria H. A. Santana 《Journal of Thermal Analysis and Calorimetry》2012,108(1):101-108
This study focuses on the physicochemical characterization of lipid materials useful for the production of the so-called solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). The chosen lipids were Dynasan®114 (glyceril trimyristate) and Dynasan®118 (glyceril tristearate) as solid lipids (SL), melting temperature above 80 °C, and Miglyol®812 (caprylic/capric triglyceride) and Miglyol®840 (propylene glycol dicaprylate/dicaprate) as liquid lipids (LL), crystallizing below ?15 °C. Raw lipids (pure or SL:LL mixtures) were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and Polarized Light Microscopy (PLM), before and after tempering at 80 °C for 1 h. The selected SL:LL combination was 70% (Dynasan®114 and 118) and 30% (Miglyol®812 and 840) for the production of SLN and NLC by high-pressure homogenization (HPH), respectively. Particles with a mean size of 200 nm (polydispersity index <0.329) and zeta potential of ?15 mV were obtained, and their long-term stability was confirmed for 3 months of storage at 7 °C. 相似文献
19.
Silvia Dulanská Boris Remenec L’ubomír Mátel Igor Antalík 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):97-101
Two separation techniques for plutonium determination using AnaLig® Pu02 molecular recognition technology product (MRT) and extraction chromatography TRU® resin were tested. The methods performance was investigated by analysis of National Physical Laboratory (NPL-Alpha-Beta High, ABH 2003, 2005) intercomparison test samples. The results obtained for both procedures were compared in terms of activities and recoveries. Data analysis showed good agreement with the reference values. The AnaLig® Pu02 separation method for 239,240Pu, 238Pu determination was successfully validated with the same performance as the TRU® resin method. 相似文献
20.
The high-field 19F and 91Zr NMR method is used to study the hydrolysis and polycondensation of hexafluorozirconate ZrF62− in aqueous and water-peroxide solutions. During hydrolysis in aqueous solutions only ZrF62− and F− ions were observed by NMR, however, in the water-peroxide medium, an intermediate product of hydrolysis ([F5Zr-OO-ZrF5]4− dimer) was detected. The dimer structure is confirmed by 19F and 91Zr NMR. In high fields (19F NMR frequency > 200 MHz), the fluorine exchange between ZrF62− and F− is slow in the 19F NMR scale and has a multisite character. 相似文献