pX Data Research Articles

Dibutyl Citrate Synthesis, Physicochemical Characterization, and Px Data in Mixtures with Butanol

Dibutyl citrate (DBC) was synthesized via partial esterification of citric acid (CA) with n-butanol (BuOH) and characterized for the first time. Then, the monoacid diester was isolated from the reactive mixture by using a pH-controlled solvent extraction procedure. The identity of the obtained product was verified by NMR spectroscopy, finding that it corresponds to a mixture of asymmetric and symmetric isomers. The obtained product was characterized by thermogravimetric and differential scanning calorimetry analysis and by density and viscosity measurements. As per the calorimetric analysis, DBC exhibited a crystallization point below 213 K, a decomposition temperature of 541 K, and an average heat capacity of 2.461 kJ/kg K in the evaluated temperature range (320–375 K). The average liquid density and viscosity in the studied temperature interval (298–313 K) were 1.122 g/cm3 and 2.03 Pa·s, respectively. Additionally, isothermal vapor–liquid equilibrium data (P–x) in mixtures containing the obtained DBC an...

Thermodynamic consistency testing of PTx-data via the Gibbs-Helmholtz equation 2.: Methodology and limitations

Measurement of mixture vapor-pressure data, Px or Tx (PTx) data, is a fast, efficient, and often more accurate method to determine low-pressure binary vapor–liquid equilibrium (VLE) data compared with measurement of PTxy data in re-circulating equilibrium stills. PTx data are the minimum necessary to specify VLE according to the phase rule so that Gibbs–Duhem slope and area thermodynamic consistency tests are not possible. However, GE/RT data derived from PTx data measured at several temperatures can be compared to measured HE data with the Gibbs–Helmholtz (GH) equation, GE/RT=HE/RT–SE/R. This comparison can be used as a thermodynamic consistency test for PTx data. Previous work (Fluid Phase Equilibria, 14 (1983) 383–392) showed that random errors in pressure measurement large enough to give GH inconsistency usually are not large enough to cause unacceptable errors in the vapor compositions calculated by Barker's method. This present work demonstrates that using a Redlich–Kister GE expansion at each temperature rather than using a Local Composition GE model, e.g., NRTL, fitted to all of the Px data over the entire temperature range is an effective methodology for GH testing; this methodology is demonstrated by analysis of high-precision ethanol + water Px data. In addition, the special GH testing problems presented by nearly-ideal systems are illustrated by analysis of recent high-precision ethanol + n-propanol Px data. Other limitations of and recommendations for Gibbs–Helmholtz testing of VLE data are discussed.

Chemical Crystallography at the Australian Synchrotron MX Beamlines

The Macromolecular Crystallography (MX) Beamlines at the Australian Synchrotron collect data on protein samples (PX) and chemical samples (CX). This broad range of sample types requires us to consider a number of experimental and data processing considerations. Protein samples have very large unit cells but diffract weakly, the chemical samples on the other hand have very small unit cell and diffract comparatively strongly. From an experimental point of view, this requires substantially different geometrical considerations which can be handled by changing the energy of the monochromated X-rays and detector distance. Another consideration is detector type, the detectors at the MX beamlines are from the Area Detector Systems Corporation (ADSC) and they have generally been used for PX data collections. This has lead to investigation regarding high incidence angle phosphor thickness corrections. As the detectors have mainly been used for PX work, the software for sample handling has also been developed with PX considerations rather than CX. For example, the software for space group determinations is set my default to assumes that your space group is only ever one of the 65 space groups that don't contain mirror, inversion or glide operations. Another area of interest is the way data scaling is handled. The data is often scaled with PX data for a number of reasons, with the most common scaling of data is due t the prevalence of radiation damage to the samples. By contrast the most common form of scaling for CX data is for sample anisotropy in strong absorbers. A discussion of the challenges faced for the chemical crystallography experiments at the Australian Synchrotron will be presented.

FRI0558 One approach to evaluating step therapy policies for immune disorder specialty pharmaceuticals

BackgroundRheumatology practices are increasingly exposed to patient health care benefit plans that include designs such as “step therapy” (ST) policies which may affect medication choice. Managed care companies implement ST...

Consistency test of solubility data of ammonia in ionic liquids using the modified Peng–Robinson equation of Kwak and Mansoori

Phase equilibrium data of temperature, pressure and solubility (T–P–x) of ammonia in different types of ionic liquids over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. The modified Peng–Robinson equation of state proposed by Kwak and Mansoori is used for correlating the isothermal PX data and a flexible thermodynamic consistency method applied to analyze forty seven isothermal P–x data available in the open literature. Modeling is found acceptable in all cases, meaning that deviations in correlating the data are low, proving at the same time the claimed flexibility of a well-founded model that uses simple van der Waals mixing rules. For all cases, the thermodynamic consistency method gives a clear conclusion about consistency or inconsistency of a set of experimental T–P–x data based on the established criteria.

An efficient approach to optimal interpolation of experimental data

In this work, a computational method is proposed in order to choose the best interpolation function for experimental data. The optimal interpolation function follows the natural tendency of data, suffers a minimal influence by removing one data point, does not present over fitting and yields the best representation for large or rough data sets. High pressure Px data of binary mixtures containing ionic liquid were used as case studies: supercritical CO 2 + 1-hexyl-3-methyl imidazolium hexafluorophosphate {[hmim][PF 6]}, supercritical CO 2 + 1-butyl-3-methyl imidazolium tetrafluoroborate {[bmim][BF 4]} and supercritical CHF 3 + 1-butyl-3-methyl imidazolium hexafluorophosphate {[bmim][PF 6]}. The common practice of using the correlation coefficient to analyze the accuracy of the interpolation model is critically discussed. As a validation of the method, a thermodynamic consistency test is applied to the interpolated data. The results show that the mean values of the interpolation error for CO 2 + [hmim][PF 6], CO 2 + [bmim][BF 4] and CHF 3 + [bmim][PF 6] are 0.47%, 0.33% and 0.13%, respectively. These values are within the reported experimental error, which has a range from 0.04% to 1.7%.

Photoproduction with a leading proton at HERA

The total cross section for the photoproduction process with a leading proton in the final state has been measured at γp centre-of-mass energies W of 91, 181 and 231 GeV. The measured cross sections apply to the kinematic range with the transverse momentum of the scattered proton restricted to p T ⩽0.2 GeV and 0.68⩽ z⩽0.88, where z= E p ′/ E p is the scattered proton energy normalised to the beam energy. The cross section d σ γp→ Xp′ ( W, z)/d z is observed to be independent of W and z within the measurement errors and amounts to (8.05±0.06 ( stat)±0.89 ( syst)) μb on average. The data are well described by a Triple Regge model in which the process is mediated by a mixture of exchanges with an effective Regge trajectory of intercept α i(0)=0.33±0.04 ( stat)±0.04 ( syst) . The total cross section for the interaction of the photon with this mixture ( γα i → X) can be described by an effective trajectory of intercept α k(0)=0.99±0.01 ( stat)±0.05 ( syst) . Predictions based on previous triple Regge analyses of pp→ pX data assuming vertex factorisation are broadly consistent with the γp data. The measured cross sections are compared with deep inelastic scattering leading proton data in the same region of z and p T for photon virtuality Q 2>2.5 GeV 2 . The ratio of the cross section for leading proton production to the total cross section is found to rise with Q 2.

Direct study of the lifetime and acceleration of a coloured nucleon

We propose a method of studying directly the confinement part of the force due to the coloured field, and the time that a coloured hadron remains coloured. Applying the method topp→pX data we find that the mean time for colour neutralization of a coloured nucleon is 1.2±0.1 fm/c or (3.9±0.3)×10−24 s.

Phenomenological tests of f-dominated pomeron in inclusive reactions

We present results of an analysis of data on several inclusive processes which test the hypothesis of f-dominance of the pomeron (FDP). Both non-diffractive and diffractive reactions are studied. In the first case a comparison of pairs of fragmentation processes (one exotic, the other non-exotic) are considered so that the pomeron and f-exchange contributions can be estimated and their ratio compared with that obtained from total cross sections. We find that the f:P ratio is largely independet of both t and M 2/ s and its value is consistent with that given by total cross sections, thus giving strong support to the FDP hypothesis. For the diffractive inclusive process, the hypothesis relates all the couplings PPP, PPM, MMP, MMM and the interference term PMP to one overall coupling. We carry out a triple-Regge analysis of the world data on pp → pX using the FDP couplings together with π-exchange contributions which are consistent with the pn → pX data. Good agreement is obtained with the data and with the conventional triple-Regge fits (which have no constraints on the couplings) except for small t. The data at small t, including the pd → dX data, almost scale with energy and require a substantially smaller value of PPM/PPP than that according to the FDP hypothesis. On the whole however, we feel that the predictions of FDP for inclusive reactions are experimentally

Triple Regge and finite mass sum rule analysis of the inclusive reaction pp → pX

We present the results of a comprehensive analysis of inclusive pp → pX data in terms of the triple Regge formalism. We use all available data and in the theory include PPP, PPR, RRP, RRR, ππP, and ππR terms. Further we examine the importance of interference terms (e.g. PRP) and present solutions with the triple pomeron either vanishing or non-vanishing at t = 0. Predictions are made for both pp → pX and pn → pX at NAL and ISR energies. In addition, finite mass sum rules (FMSR), constructed from low-mass diffractive dissociation data, are shown to be in good agreement with the high-energy, high-mass fits. The energy, momentum transfer and moment dependence of the FMSR are discussed in detail.

Prong cross-sections from a realistic two-component model

The inclusive pp → pX data, supporting a large triple Pomeron contribution, is invoked to predict the diffractive multiplicity distributions. Poisson decay is assumed for the excited cluster. The predicted diffractive prong cross-sections agree with the empirical estimates at 200 GeV c and suggest a significant broadening at 1500 GeV c (giving a rise in σ T ∼ 2.5 mb). Consequently the full prong distribution should develop no dip.