The Clauser–Horne approach used to derive experimentally measurable quantities for performing experiments on EPR paradox based on Type-I Spontaneous Parametric Down Conversion (SPDC) sources is discussed. It is proved that in this case the deduced Bell's type inequality does not correctly express separability and causality. A deeper analysis of the problem shows that the Clauser–Horne hypothesis of factorizability of joint detection probability cannot be considered so general as to describe this physical situation. 相似文献
We have investigated the distribution of conformations and orientations for a simple internal rotor molecule, 2,2'-bithienyl dissolved in liquid crystal solvents, by re-analysing published proton dipolar coupling data with the maximum entropy internal order method (MEIO). We show that detailed, model independent, conformational information can be obtained when data of sufficiently high quality are available. We also propose a novel and convenient representation method for the orientational-conformational coupling. 相似文献
This work is concerned with the rationalization and prediction of solvent and temperature effects in nucleophilic addition to alpha-chiral carbonyl compounds leading to facial diastereoselectivity. We study, using molecular dynamics simulations, the facial solvation of (R)-2-phenyl-propionaldehyde in n-pentane and n-octane at a number of temperatures and compare it with experimental selectivity data for the nBuLi addition leading to syn- and anti-(2R)-2-phenyl-3-heptanol, which give nonlinear Eyring plots with the presence of inversion temperatures. We have found from simulations that the facial solvation changes with temperature and alkane. Moreover, by introducing a suitable molecular chirality index we have been able to predict break temperatures (T(CI)) for the two solvents within less than 20 degrees of the inversion temperatures experimentally observed in the diastereoselective nBuLi addition. We believe this could lead to a viable approach for predicting inversion temperatures and other subtle solvent effects in a number of stereoselective reactions. 相似文献
A high-precision exact-matching quadruple isotope dilution method (ID4MS) was employed for the quantitation of nitrate in an air-dried spinach powder Certified Reference Material (CRM). The analyte was extracted in hot water following addition of 15NO\({}_{3}^{-}\) internal standard. The blend was then treated with sulfamic acid to remove nitrite and with triethyloxonium tetrafluoroborate to promote aqueous conversion of nitrate into volatile EtONO2. The derivative was analyzed by headspace GC–MS with 3-min elution time. The method performance was validated with a series of tests which demonstrated adequate selectivity and ruggedness. This method supported the development of novel SPIN-1 CRM giving a modest contribution to its uncertainty (uchar = 0.85%). With respect to previous attempts, the SPIN-1 was proven stable, homogeneous (uhom = 0.44%), and suitable for spinach monitoring under EU regulations. On dried basis, the nitrate content of SPIN-1 was found to be 22.53 ± 0.43 mg/g (Uc = 1.9%, k = 2). The material was also used in an inter-laboratory study where four laboratories employed a total of ten measurement methods.
Abstract The title compounds (4b-d) together with the benzothiazolines (5b-d) have been obtained by a reaction between 2,2′-dithiodianiline (1) and β-keto esters (2b-d). The reaction between 1 and the β-keto ester 2a gives 1,4-benzothiazine 3a in addition to the benzothiazoline 5a. It has been established that the 1,4-benzothaizines 4b-d undergo an acid-catalysed thermal rearrangement involving a [1,3] shift of the sulfur atom, giving rise to the isomeric 1,4-benzothiazines 3b-d. 相似文献
The reaction between 2-aminothiophenol 1 and acetylenic nitriles or esters 2a-d leads to the vinyl thio-ethers 3a-d. The conversion of 3 into benzothiazoles 8 and/or 1,4-benzothiazines 9 , in boiling dimethyl sulfoxide, has been achieved. A possible pathway involving benzothiazolines 5 as key intermediates is suggested. 相似文献
The plasma plume induced during laser welding of metals is a mixture of metal vapour, coming from the vaporised weld pool surface and shielding gas. The influence of the shielding gas on the welded joints quality is not yet well understood and very few investigations, to the best of our knowledge, were addressed to study its role in case of welding of aluminium–magnesium alloys. In this paper we present a study of the dynamics of plasma plume produced in laser welding of 5xxx aluminium alloys by means of correlation spectroscopy. By our results we can correlate the influence of the welding speed, in case of ineffective gas shielding, to the loss of alloying elements. Finally, the results obtained are consistent with the EDX analysis performed in post-processing on the welded joints. 相似文献