The reorientation of Cd2+-vacancy and Pb2+-vacancy complexes in KCl

The relaxation of Pb²⁺-vacancy and Cd²⁺-vacancy dipoles in purified KCl crystals was studied using a double crystal dc polarization method which self-corrects relaxation effects due to spurious causes. In the radius range from Cd²⁺ to Ba²⁺ these results and most others support Dreyfus' model. The reciprocal relaxation times for each impurity are given by

$\text{τ}{}^{\mathrm{?1}}{}_{\mathrm{<mtext>Cd</mtext>}}\text{=2.06x10}{}^{12}\text{exp(?s0.64±0.01}\text{eV}\text{)}\text{kT}$

;

$\text{τ}{}^{\mathrm{?1}}{}_{\mathrm{<mtext>Pb</mtext>}}\text{=1.19x10}{}^{13}\text{exp(?0.69±0.01}\text{eV}\text{)}\text{kT}$

.It is also shown that the presence of H₂O or its products greatly perturb the relaxation times observed.     

Experimental and Computational Study of the Thermal Decomposition of 3‐Methyl‐3‐buten‐1‐ol in m‐Xylene Solution

An experimental study of the thermal decomposition of a β‐hydroxy alkene, 3‐methyl‐3‐buten‐1‐ol, in m‐xylene solution, has been carried out at five different temperatures in the range of 513.15–563.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s^?1) = (25.65 ± 1.52) ? (17,944 ± 814) (kJ·mol^?1)·T^?1. A computational study has been carried out at the M05–2X/6–31+G(d,p) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. There is a good agreement between the experimental and calculated rate constants and activation Gibbs energies. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis, which provides the natural atomic charges and the Wiberg bond indices. Based on the results obtained, the mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state, being a concerted and slightly asynchronous process. The results have been compared with those obtained previously by us (Struct Chem 2013, 24, 1811–1816) for the thermal decomposition of 3‐buten‐1‐ol, in m‐xylene solution. We can conclude that in the compound studied in this work, 3‐methyl‐3‐buten‐1‐ol, the effect of substitution at position 3 by a weakly activating CH₃ group is the stabilization of the transition state formed in the reaction and therefore a small increase in the rate of thermal decomposition.     

Structural and Kinetic Aspects of Blood Plasma Protein Adsorption on the Surface of Hydrophobic Polymers

Abstract

Due to the wide use of polymers in medicine, researchers are required to solve a very important problem–to understand the interaction between materials of nonphysiological origin and the surrounding biological liquids, and tissues, particularly blood.     

Abdominal imaging studies: comparison of diagnostic accuracies resulting from ultrasound, computed tomography, and magnetic resonance imaging in the same individual

We retrospectively compared the diagnostic accuracy of abdominal ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) studies performed on the same individual to determine the relative performance of these modalities in the evaluation of disease processes, arising from different intra-abdominal organ systems. We retrospectively reviewed all procedure codes accrued by our abdominal imaging section during a 1-year period to determine how many patients underwent all three imaging procedures in our institution within a 2-week interval. These cases were then further evaluated to determine: (1) the primary organ system of disease involvement, (2) the final diagnosis, and (3) the imaging modality that provided the most accurate information upon which appropriate medical management was based. Imaging findings were determined by review of diagnostic reports, and medical management was determined by chart review. Two thousand six hundred-ninety five patients underwent ultrasound, 4,394 patients underwent CT, and 872 patients underwent MRI for the investigation of abdominal disease. Among these 5,126 patients, 26 underwent sequential US, CT, and MRI evaluation within a two-week interval. Appropriate clinical management was based on the US findings in 12/26 cases (46%; 95% CI: 27-67%), CT findings in 16/26 cases (62%; 95% CI: 41-80%), and MRI findings in 24 cases (92%; 95% CI: 75-99%). Significant differences in directing appropriate clinical management were found when comparing the relative diagnostic accuracies of MRI to US (p = 0.0003) and MRI to CT (p = 0.009). However, differences were not significant when comparing CT to US (p = 0.27). All final diagnoses in a given patient were accurately determined by US in 7/26 cases (27%), by CT in 10/26 cases (38%), and by MRI in 23/26 cases (88%). When analyzed according to individual diagnoses (61 total), US detected 33 of 61 (54%) abnormalities, CT detected 41 (67%) abnormalities, and MRI detected 51 (84%) abnormalities. US correctly characterized 32 (52%) abnormalities, CT correctly characterized 36 (59%) abnormalities, and MRI correctly characterized 49 (80%) abnormalities. Ultrasound, CT, and MR imaging correctly diagnosed the disease process in 3 of 12 (25%), 3 of 12 (25%), and 10 of 12 (83%) patients, respectively, with liver disease; 2 of 9 (22%), 6 of 9 (66%), and 9 of 9 (100%) patients, respectively, with pancreatic disease; 17 of 17 (100%), 8 of 17 (47%), and 10 of 17 (58%) patients, respectively, with gallbladder and biliary disease; 2 of 8 (25%), 5 of 8 (63%), and 5 of 8 (63%) patients, respectively, with renal disease; 0 of 3 (0%), 2 of 3 (66%), and 3 of 3 (100%) patients, respectively, with adrenal disease; and 8 of 12 (75%), 12 of 12 (100%), and 12 of 12 (100%) patients with free intraperitoneal fluid. Our results provide new information, regarding the relative benefits of ultrasound, CT, and MRI for the investigation of abdominal diseases at our institution. This initial data suggests that ultrasound provides the most accurate diagnoses in the investigation of gallbladder disease; MRI provides the most accurate diagnoses in the investigation of hepatic, adrenal, and pancreatic disease; and either CT or MRI may be the most appropriate first imaging study for the detection of renal disease.     

Second-order necessary conditions in semismooth optimization

First- and second-order conditions are given which are necessary for a functionf to have a local minimal value atx ^* inR ⁿ. It is assumed thatf is locally Lipschitzian nearx ^* and semismooth atx ^*. The necessary conditions are expressed in terms of the generalized gradients of nonsmooth analysis and certain second-order directional derivatives. The method of proof bears no resemblance to standard methods. Three special cases are discussed here, but applications to constrained problems are made elsewhere.     

Scheduling reconstruction operations with modes of execution

Since the decline of the Cold War, the risk of major conflict between powerful, industrialized nations has decreased. Insecurities in the 21st century are more apt to arise from the debris of imploding states. Such situations may require intervention—military or otherwise—by concerned states. To meet this new operational challenge, nations must adapt their planning procedures to account for Security, Stabilization, Transition, and Reconstruction Operations (SSTRO). This paper develops a project scheduling framework for post-conflict reconstruction that schedules reconstruction activities to maximize the positive impact to the local economy during the initial phase of SSTRO. Specifically, this paper builds on the Multimode Resource Constrained Project Scheduling Problem with Generalized Precedence Relations (MM-RCPSP-GPR) using goal programming to maximize the reconstruction operations’ positive impact to local population's economic welfare. This MM-RCPSP-GPR variant is applied to a notional example to illustrate its potential use in post-conflict SSTRO. The basic framework can be extended to other settings.