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971.
S. Jha H. M. Seyoum Sherif Yehia Charilaos Mitros G. M. Julian R. A. Dunlap A. Vasquez J. G. M. Da Cunha S. M. M. Ramos 《Hyperfine Interactions》1986,28(1-4):491-494
We have investigated the systematics of hyperfine magnetic field on a fixed probe at the Z-site in Heusler alloys Rh2MnZ as the valence of Z (sp element) is varied. The hmf on119Sn in Rh2MnIn.98
119Sn02 has been measured at 293K and 77K. In Rh2Mn1.12Sb.86
119Sn.02 the hmf on121Sb has been measured at 77 K, and on119Sn at 293 K and 77 K. The results are compared with the hmf on119Sn in Rh2Mn Ge.98
119Sn.02 Rh2Mn Sn, and Rh2Mn Pb.98
119Sn.02.Supported by the University Research Council, University of CincinnatiSupported by the Natural Sciences and Engineering Research Council of Canada 相似文献
972.
973.
Mathematische Zeitschrift - 相似文献
974.
The reactions of O3 with ethylene, allene, 1,3-butadiene, and trans-1,3-pentadiene have been studied in the presence of excess O2 over the temperature range 232 to 298 K. The initial O3 pressure was varied from 4–18 mtorr, and the olefin pressure was varied from 0.1 to 4.5 torr (ethylene), 2.8 to 39.6 torr (allene), 52.7 to 600 mtorr (1,3-butadiene) or 26.2 to 106 mtorr (trans-1,3-pentadiene). The O3 decay was monitored by ultraviolet absorption. The reactions are first order in both O3 and olefin, and the rate coefficients are independent of the O2 pressure. For the O3-ethylene system, various diluent gases (O2, N2, air) were used and the rate coefficients were found to be independent of the nature of the diluent gas. The various rate coefficients fit the Arrhenius expressions (k in cm3 s?1): where the reported uncertainties are one standard deviation and R is in cal/mol K. 相似文献
975.
Anna ChmielPawel Sobkowicz Julian SienkiewiczGeorgios Paltoglou Kevan BuckleyMike Thelwall Janusz A. Ho?yst 《Physica A》2011,390(16):2936-2944
We present an empirical study of user activity in online BBC discussion forums, measured by the number of posts written by individual debaters and the average sentiment of these posts. Nearly 2.5 million posts from over 18 thousand users were investigated. Scale-free distributions were observed for activity in individual discussion threads as well as for overall activity. The number of unique users in a thread normalized by the thread length decays with thread length, suggesting that thread life is sustained by mutual discussions rather than by independent comments. Automatic sentiment analysis shows that most posts contain negative emotions and the most active users in individual threads express predominantly negative sentiments. It follows that the average emotion of longer threads is more negative and that threads can be sustained by negative comments. An agent-based computer simulation model has been used to reproduce several essential characteristics of the analyzed system. The model stresses the role of discussions between users, especially emotionally laden quarrels between supporters of opposite opinions, and represents many observed statistics of the forum. 相似文献
976.
This note is a response to a paper of Ho that was published in Information and Management Sciences, 20 (2009), 161–171. We find two reasonable criteria to insure the existence and uniqueness of the optimal solution. Based on the same numerical examples, if we directly compare our results with that by Ho, then the improvement is about 30%. Meanwhile, after revising the computation errors, then our analytical approach improves 4%. 相似文献
977.
Phosphorylation at histidine residues occurs frequently in biology, but is often overlooked in proteomics experiments due to extreme acid lability. A new method utilizing histidine labeling with iodine to record information about phosphorylation is described. Essentially, phosphorylated histidine residues are not labeled while unmodified histidine undergoes complete iodination. Iodination is stabile both under acidic conditions, and upon collisional activation in the gas phase. This enables site-specific information to be retained with standard liquid chromatography separations and tandem mass spectrometry by collisional activation. Semi-quantitative information about the relative amounts of phosphorylated versus unmodified states can also be easily obtained from the relative ion abundances. This new method should provide a pathway forward for analyzing histidine phosphorylation in complex systems. 相似文献
978.
Bloch ED Murray LJ Queen WL Chavan S Maximoff SN Bigi JP Krishna R Peterson VK Grandjean F Long GJ Smit B Bordiga S Brown CM Long JR 《Journal of the American Chemical Society》2011,133(37):14814-14822
The air-free reaction between FeCl(2) and H(4)dobdc (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) in a mixture of N,N-dimethylformamide (DMF) and methanol affords Fe(2)(dobdc)·4DMF, a metal-organic framework adopting the MOF-74 (or CPO-27) structure type. The desolvated form of this material displays a Brunauer-Emmett-Teller (BET) surface area of 1360 m(2)/g and features a hexagonal array of one-dimensional channels lined with coordinatively unsaturated Fe(II) centers. Gas adsorption isotherms at 298 K indicate that Fe(2)(dobdc) binds O(2) preferentially over N(2), with an irreversible capacity of 9.3 wt %, corresponding to the adsorption of one O(2) molecule per two iron centers. Remarkably, at 211 K, O(2) uptake is fully reversible and the capacity increases to 18.2 wt %, corresponding to the adsorption of one O(2) molecule per iron center. Mo?ssbauer and infrared spectra are consistent with partial charge transfer from iron(II) to O(2) at low temperature and complete charge transfer to form iron(III) and O(2)(2-) at room temperature. The results of Rietveld analyses of powder neutron diffraction data (4 K) confirm this interpretation, revealing O(2) bound to iron in a symmetric side-on mode with d(O-O) = 1.25(1) ? at low temperature and in a slipped side-on mode with d(O-O) = 1.6(1) ? when oxidized at room temperature. Application of ideal adsorbed solution theory in simulating breakthrough curves shows Fe(2)(dobdc) to be a promising material for the separation of O(2) from air at temperatures well above those currently employed in industrial settings. 相似文献
979.
Chen ZP Li LM Yu RQ Littlejohn D Nordon A Morris J Dann AS Jeffkins PA Richardson MD Stimpson SL 《The Analyst》2011,136(1):98-106
The development of reliable multivariate calibration models for spectroscopic instruments in on-line/in-line monitoring of chemical and bio-chemical processes is generally difficult, time-consuming and costly. Therefore, it is preferable if calibration models can be used for an extended period, without the need to replace them. However, in many process applications, changes in the instrumental response (e.g. owing to a change of spectrometer) or variations in the measurement conditions (e.g. a change in temperature) can cause a multivariate calibration model to become invalid. In this contribution, a new method, systematic prediction error correction (SPEC), has been developed to maintain the predictive abilities of multivariate calibration models when e.g. the spectrometer or measurement conditions are altered. The performance of the method has been tested on two NIR data sets (one with changes in instrumental responses, the other with variations in experimental conditions) and the outcomes compared with those of some popular methods, i.e. global PLS, univariate slope and bias correction (SBC) and piecewise direct standardization (PDS). The results show that SPEC achieves satisfactory analyte predictions with significantly lower RMSEP values than global PLS and SBC for both data sets, even when only a few standardization samples are used. Furthermore, SPEC is simple to implement and requires less information than PDS, which offers advantages for applications with limited data. 相似文献
980.
The first enantioselective total synthesis of the originally assigned structure of lyngbouilloside aglycon has been achieved using a particularly flexible route featuring an acylketene macrolactonization of a tertiary methyl carbinol as the key step. Comparison of the C13 chemical shifts of our synthetic aglycon with the ones pertaining to natural lyngbouilloside and lyngbyaloside C resulted in a possible stereochemical reassignment of the C11 stereogenic center. 相似文献