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51.
Douglas L. Currell Harold Goldwhite Susan Lim Nita Patel 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):35-38
Abstract Synthetic phosphonocarboxylates, diphosphonates, polyphosphates, and some triphosphonic acids were studied as effectors in the binding of dioxygen to human hemoglobin. Ethane-1,2-diphosphonic acid, and triphosphate anion were strong effectors. 相似文献
52.
David Bérardan Lidong Zhao Loreynne Pinsard-Gaudart Nita Dragoe 《Physica C: Superconductivity and its Applications》2010,470(2):165-167
We present results of transport and magnetic properties measurements performed on polycrystalline NdFe0.9Rh0.1AsO. Despite the large size difference between Fe and Rh elements, this compound undergoes a superconducting transition with Tc ~ 15 K. We have compared the transport properties of this Rh-doped oxypnictide with that of optimally doped NdFeAsO0.88F0.12. Contrary to this latter compound, a strong upturn of the normal-state resistivity occurs above Tc, and no peak of the thermopower has been observed. 相似文献
53.
Oana Ursache Constantin Gaina Viorica Gaina Nita Tudorachi Alexandra Bargan Cristian-Dragos Varganici Dan Rosu 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1471-1481
Thermoreversible networks obtained by the Diels–Alder cycloaddition reaction of poly(vinyl furfural) with urethane bismaleimides containing polyether chain were synthesized. The formation of the networks was confirmed by attenuated total reflectance in conjunction with Fourier transform infrared spectroscopy (ATR–FTIR). The materials thermal properties were investigated using differential scanning calorimetry (DSC) and a coupling of dynamic thermogravimetry with Fourier transform infrared spectroscopy and mass spectrometry (TG–FTIR–MS) for pyrolysis behaviour under nitrogen atmosphere. A thermal decomposition mechanism of the networks and poly(vinyl furfural) was discussed via evolved gas analysis. The thermoreversibility of the networks was demonstrated by the presence of the endothermic peak characteristic to the retrodienic process on the DSC heating curves and also the appearance of the exothermic peak, due to the dienic process, on the DSC cooling curve. The dynamic contact angle and free surface energy values of the networks were determined. Measures of the heterogeneity and roughness of the surfaces suggested that the surfaces of the networks’ films are more homogenous than the initial poly(vinyl furfural) surface. Dynamic water vapour sorption studies were conducted. 相似文献
54.
Zal?U’yun?Wan?MahmoodEmail author Che?Abd.?Rahim?Mohamed Abdul?Kadir?Ishak Nita?Salina?Abu?Bakar Kamaruzzaman?Ishak 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):953-959
Marine sediment cores were collected from two stations at East Malaysia coastal waters on June 2004. Activity concentrations
of 210Pb in sediment core were ranged from 11 Bqkg−1 to 84 Bqkg−1 dry wt. for SR 01 and 4 Bqkg−1 to 66 Bqkg−1 dry wt. for SB 03. Meanwhile, activity concentrations of 226Ra in sediment core were varied significantly depending on the sampling location of SR 01 and SB 03 with ranged 17–26 Bqkg−1 dry wt. and 8–11 Bqkg−1 dry wt., respectively. The activity ratios of 210Pb/226Ra were no significantly different at all sampling stations with an average of 1.78. Refer to the entire results; the activities
of 210Pb and 226Ra were higher at station SR 01 than station SB 03, but contrast with ratio of 210Pb/226Ra. The reasons of different 210Pb and 226Ra activity concentration and distribution of their ratios were strictly related to their half lives, environment origin,
potential sources and behavior. 相似文献
55.
O. A. Rusu S. Dreve R. Cs. Begy D. C. Nita L. D. Bobos C. Cosma 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):241-245
Alpha spectrometry is an extremely useful and sensitive for detection of alpha-emitting nuclides. Contamination of the silicon
detectors for low-level alpha spectrometry by recoil nuclides is a serious problem in the measurement of alpha emitters decaying
to daughter nuclides with short half-lives. This unwanted contamination leads to decreased measurement sensitivity causing
a degradation of the limit of detection. The simplest method to prevent this radioactive contamination of detector is to use
a catcher film between the alpha source and the detector. In this work we describe the obtaining of the thin formvar films
as stopper foils for recoil nuclei and we investigated the influence of these films on alpha spectrometry parameters, as energy
shift (~30 keV) and resolution (~7%). No significant deterioration of the alpha spectrometry parameters was observed when
using thin formvar films. Using the ASTAR web databases, which calculate stopping powers for alpha particles, the thickness
of formvar films was estimated to be about 5.355 × 10−5 g/cm2. The measurements were performed with an ORTEC SOLOIST alpha spectrometer with PIPS detector. 相似文献
56.
57.
In the present paper Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, of Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphor were synthesized by the wet chemical method. Thermoluminescence (TL) characteristics of Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphors were studied for 5 Gy γ-ray dose. In TL glow curve, two peaks have been observed at 129°C and 224°C for different concentrations of Ce and Dy, whereas Mn peaks at 212°C. The same host is also tried for Ce, Dy (peaks at 126, 219) and Ce, Mn (248°C). A significant single peak is observed in the case of Na3SO4Cl:Mn and Na3SO4Cl:Ce, Mn. This may be due to the effect of activators. It is found that intensity tends to be increase with increased concentrations of the activators. The TL glow curves of the phosphors have been recorded and irradiated at a rate of 0.39 kGy h?1 for 5 Gy γ-rays dose. It is also found that all the phosphors are less sensitive as compared with Thermoluminescence dosimetry-CaSO4: Dy for the same γ-rays dose. The paper discuses the preliminary TL characteristics and effect of γ-rays on Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphors. 相似文献
58.
Two thermoset systems based on maleimides and diglycidyl ether of bisphenol A (DGEBA) cured with p-aminobenzoic acid were characterized in terms of thermal and electrical behavior. Thermal characterization has been undertaken by means of thermogravimetric analysis in nitrogen atmosphere up to 600°C using simultaneous thermogravimetric/Fourier transform infrared/mass spectrometry (TG/FT-IR/MS) analysis. In the first stage of thermal degradation, the global kinetic parameters [activation energy (Ea) and preexponential factor (log A1 (s−1))] were calculated using the isoconversional method of Friedman. The energies variation as well as the shape of the differential thermal analysis curves suggests that the thermal decomposition process occurred in multiple stages. The evolved gases analysis was conducted by simultaneous TG/FT-IR/MS coupled techniques. Dielectric relaxation spectroscopy characterization was also made. 相似文献
59.
We present a method for measuring the weak phase gamma using isospin analysis of three body B decays into Kpipi channels. Differential decay widths and time-dependent asymmetry in B(d)-->K(S)pi(+)pi(-) mode needs to be measured into even isospin pipi states. The method can be used to extract gamma, as well as the size of the electroweak penguin contributions. The technique is free from assumptions like SU(3) or neglect of any contributions to the decay amplitudes. By studying different regions of the Dalitz plot, it may be possible to reduce the ambiguity in the value of gamma. 相似文献
60.
Diethoxytriphenylphosphorane (DTPP) efficiently oxaphosphoranylates methyl α-d -glucopyranoside to afford two unstable isomeric 1,3,2λ5-dioxaphospholanes. Thermolysis (60–90°C) of these 1,3,2λ5-dioxaphospholanes affords only two of four possible isomeric anhydropyranosides. Two distinct intermediate betaines and their unique “pre-transition state” chair or twist-boat structures are used to rationalize the regiochemistry-attending cyclodehydration. The decomposition of these rapidly interconverting 1,3,2λ5-dioxaphospholanes is accelerated in the presence of lithium bromide (LiBr) to afford a single anhydropyranoside. 相似文献