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501.
The conductivity equation of Lee and Wheaton is expanded in a power series in the ionic strength I. Different levels of approximation are analyzed and it is shown that for unsymmetrical electrolytes it is necessary to keep the terms I3/2lnI and I2 to maintain the performance of the full equation. 相似文献
502.
503.
G. Xhixha G. P. Bezzon C. Broggini G. P. Buso A. Caciolli I. Callegari S. De Bianchi G. Fiorentini E. Guastaldi M. Kaçeli Xhixha F. Mantovani G. Massa R. Menegazzo L. Mou A. Pasquini C. Rossi Alvarez M. Shyti 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):445-457
Materials containing radionuclides of natural origin and being subject to regulation because of their radioactivity are known as Naturally Occurring Radioactive Material (NORM). By following International Atomic Energy Agency, we include in NORM those materials with an activity concentration, which is modified by human made processes. We present a brief review of the main categories of non-nuclear industries together with the levels of activity concentration in feed raw materials, products and waste, including mechanisms of radioisotope enrichments. The global management of NORM shows a high level of complexity, mainly due to different degrees of radioactivity enhancement and the huge amount of worldwide waste production. The future tendency of guidelines concerning environmental protection will require both a systematic monitoring based on the ever-increasing sampling and high performance of gamma-ray spectroscopy. On the ground of these requirements a new low-background fully automated high-resolution gamma-ray spectrometer MCA_Rad has been developed. The design of lead and cooper shielding allowed to reach a background reduction of two order of magnitude with respect to laboratory radioactivity. A severe lowering of manpower cost is obtained through a fully automation system, which enables up to 24 samples to be measured without any human attendance. Two coupled HPGe detectors increase the detection efficiency, performing accurate measurements on small sample volume (180 cm3) with a reduction of sample transport cost of material. Details of the instrument calibration method are presented. MCA_Rad system can measure in less than one hour a typical NORM sample enriched in U and Th with some hundreds of Bq kg?1, with an overall uncertainty less than 5 %. Quality control of this method has been tested. Measurements of three certified reference materials RGK-1, RGU-2 and RGTh-1 containing concentrations of potassium, uranium and thorium comparable to NORM have been performed. As a result, this test achieved an overall relative discrepancy of 5 % among central values within the reported uncertainty. 相似文献
504.
Umberto Bianchi Carla Cuniberti Enrico Pedemonte Corrado Rossi 《Journal of Polymer Science.Polymer Physics》1969,7(5):855-866
Heats of solution (ΔHexp) in solvents of increasing thermodynamic power have been measured for four polymers: polystyrene (PS), poly(vinyl acetate) (PVAc), polyisobutylene (PIB) and polydimethylsiloxane (PDMS). After subtraction from ΔHexp of an interaction term (calculated by the Hildebrand treatment based on solubility parameters) and the excess volume term, the quantity remaining is interpreted as the conformational energy contribution (ΔUconf) to the heat of solution. ΔUconf appears to correlate well with some basic conformational properties of the chain, such as the sign of the temperature coefficient of unperturbed dimensions derived from solution properties, and shows a monotonic behavior with α, the expansion coefficient of the polymer coil in the final solution. Numerical values of ΔUconf, at least for those cases in which polymer solubility parameters are known with some certainty, are much larger than those evaluated from rubber elasticity experiments (through the experimentally accessible value of the energy component of the force of retraction im simple elongation). 相似文献
505.
Nicola Bianchi 《Acta Physica Hungarica A》2006,27(1):55-62
Recent results from HERMES and expectations from Jlab in the hadron leptoproduction of nuclei are presented. The possible interpretations in terms of medium modifications of the parton fragmentation function and the
implications on the parton energy loss are discussed. 相似文献
506.
A Raffaelli S Pucci I Desideri C R Bellina R Bianchi P Salvadori 《Journal of chromatography. A》1999,854(1-2):57-67
Radioactive iodine (131I and 123I) labelled methylene blue is used for the early diagnosis of melanoma metastases. We studied the iodination reaction of methylene blue (using "cold" iodine) in order to characterise the iodination product(s) as far as number and position of iodine atoms introduced on the aromatic ring(s) is concerned. The reaction was carried out under the same experimental conditions used for the radioactive one, that is in a large excess of methylene blue. The ionspray HPLC-MS analysis of the reaction mixture showed that the iodinated methylene blue was present only in a very small amount and the main iodinated product was a demethylated one, coming out from the iodination of an impurity azure B. We also studied the iodination reaction of azure B in order to better explain the reaction pathway. Commercial azure B contains impurities of methylene blue and all the possible demethylated derivatives. HPLC-MS analysis of the reaction mixture allowed a complete characterisation of the iodinated and bis-iodinated products. 相似文献
507.
D. Allasia C. Angelini A. Baldini L. Bertanza F. Bianchi A. Bigi V. Bisi F. Bobisut T. Bolognese A. Borg E. Calimani P. Capiluppi S. Ciampolillo J. Derkaoui M. L. Faccini-Turluer R. Fantechi V. Flaminio A. G. Frodesen D. Gamba G. Giacomelli H. Huzita B. Jongejans I. Lippi M. Loreti C. Louedec G. Mandrioli A. Marzari-Chiesa R. Pazzi L. Ramello L. Riccati A. Romero A. M. Rossi A. Sconza P. Serra-Lugaresi A. Tenner G. van Apeldoorn P. van Dam N. van Eijndhoven D. Vignaud R. Wigmans 《Zeitschrift fur Physik C Particles and Fields》1985,27(2):239-248
The transverse momentum properties of charged hadrons produced in charged current ν and \(\bar v\) deuterium interactions are studied. The variation of <P t 2 > withW 2,Q 2,x F andz 2 is analyzed. A study of transverse momentum balance shows that soft gluon emission and some quark primordial transverse momentum with <k t 2 >?(0.4 GeV/c)2 are needed to balance highp t particles. Distributions ofp tin andP tout in and out of the event plane are presented. A three jet structure is observed for events withW 2>50 (GeV2) and with a highp t track, which is compatible with models taking into account hard gluon emission. 相似文献
508.
509.
Jorge G. Ganopolsky Hugo L. Bianchi Horacio R. Corti 《Journal of solution chemistry》1996,25(4):391-399
The densities of aqueous solutions resulting from the partial neutralization of boric acid with sodium hydroxide were measured as a function of concentration, between 375 K and 523 K at pressures close to saturation. The speciation in this system is complex, di- and triborate ions are present in addition to the monoborate ion. The concentration dependence of the apparent partial molar volume of the mixture can be described using the Pitzer equation only if the formation of the polyborate species in the concentrated solutions is taken into account. The partial molar volumes at infinite dilution for the diborate and triborate anions, obtained by assuming ideal mixing, are reported in the range of temperature studied. 相似文献
510.
The hydrazone derivatives of 4-benzoyl-1,2,3-triazole can easily be cyclised by reaction with various organic reagents (ortho esters, aldehyde and ketone compounds, phosgene, etc) which result in the incorporation of the introduced reagent's carbon atom into the new six membered ring. The newly created C-N bond of the resulting [1,2,3]triazolo[1,5-d][1,2,4]triazines displays a particular sensitivity due to the electron attracting effect of the triazole ring. Some mechanistic considerations are proposed to account for the observed results. 相似文献