The structural parameters, structural stability and bulk modulus in RE2Sn2O7by first-principles calculations

A systematic density functional theory study is performed to investigate the lattice parameters, the internal positional parameter [Formula: see text] and bond length of RE2Sn2O7(RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) pyrochlores. To analyze the structural stability in extreme conditions and verify whether bond strength varies inversely to bond length in rare-earth stannate pyrochlores, the structural parameter and bonding strength under hydrostatic pressure are studied. The tight connection between the different bond length contraction and the variation of 48[Formula: see text] oxygen positional parameter [Formula: see text] is also discovered. We calculated the bond length and the bulk modulus of RE2Sn2O7and found that the [Formula: see text]RE–O[Formula: see text] bond plays a predominant role in determining the bulk modulus. Meanwhile, the present calculations suggest that the “bimodal effect” also exists in rare-earth stannate pyrochlores.

Pelvic Incidence: A Predictive Factor for Three-Dimensional Acetabular Orientation—A Preliminary Study

Acetabular cup orientation (inclination and anteversion) is a fundamental topic in orthopaedics and depends on pelvis tilt (positional parameter) emphasising the notion of a safe range of pelvis tilt. The hypothesis was that pelvic incidence (morphologic parameter) could yield a more accurate and reliable assessment than pelvis tilt. The aim was to find out a predictive equation of acetabular 3D orientation parameters which were determined by pelvic incidence to include in the model. The second aim was to consider the asymmetry between the right and left acetabulae. Twelve pelvic anatomic specimens were measured with an electromagnetic Fastrak system (Polhemus Society) providing 3D position of anatomical landmarks to allow measurement of acetabular and pelvic parameters. Acetabulum and pelvis data were correlated by a Spearman matrix. A robust linear regression analysis provided prediction of acetabulum axes. The orientation of each acetabulum could be predicted by the incidence. The incidence is correlated with the morphology of acetabula. The asymmetry of the acetabular roof was correlated with pelvic incidence. This study allowed analysis of relationships of acetabular orientation and pelvic incidence. Pelvic incidence (morphologic parameter) could determine the safe range of pelvis tilt (positional parameter) for an individual and not a group.

XRD Based Methods of Investigation the Order - Disorder Transformation in the Spinel Structure - A Comparative Study

Three synthetic and stoichiometric 2:3 type spinels (Fd3m symmetry): MgAl2O4, MgFe2O4, NiAl2O4 with a different initial structural order in cation sublattice were investigated. Investigations by means of high temperature XRPD method at temperatures ranging from 25°C to 1100°C were carried out. Diffraction patterns at each temperature in isothermal conditions were measured. For each tested spinel changes in several temperature-dependent parameters were measured: oxygen positional parameter u(T), cell edge a0(T), cation site occupancies Occ(T) in tetrahedral and octahedral positions and a cation-anion distance in tetrahedral TO(T) and octahedral MO(T) positions. Temperatures of initial order-disorder transformation were determined on the basis of the course of these dependences. Basing on changes of the cell edge a0(T), the values of thermal expansion coefficient and for spinel before and after the beginning of order-disorder transformation, respectively, were calculated. The values of measured temperature-dependent parameters were used to calculate the degree of inversion x in the spinel structure defined as the number of 3+ cations in tetrahedral sites. In each case two methods of calculating the degree of inversion from experimental data were applied. The first method involved observing the changes in sites occupancy in the cation sublattice versus temperature, which resulted in a change of diffraction lines intensities. The second method was based on observing the changes in cation-anion distances in tetra- and octahedral coordination versus temperature. The results obtained by both methods were compared, discussed and advantages and disadvantages of each of them were presented. It was shown that when atomic scattering factors of cations 2+ and 3+ in the spinel structure differ significantly, the most precise method is the one based on changes in sites occupancies versus temperature. The method based on calculation of changes in cation-anion distances is recommended when atomic scattering factors of cations differ slightly but oxygen positional parameter and cation-anion distances changes significantly during order-disorder transformation like in normal spinel structure when effective ionic radii of 2+ and 3+ cations differ significantly.

MLE of Three-Parameter Weibull Distribution in Multi-Data Types

An algorithm is presented for maximum likelihood estimation (MLE) of three-parameter Weibull distribution in this paper, which is not only suitable for uncensored data but also appropriate for various censored data. Firstly, a unified likelihood equation under censored data and uncensored data was built. Here, the second-order convergent Newton-Raphson iteration method was applied to solve the MLE of two-parameter Weibull distribution, which had only scale parameter and shape parameter with a given positional parameter. Then, the steady and rapid Brent search method was applied to solve the optimal solution of the likelihood function just with a single variable of positional parameter. Finally, several examples were given to demonstrate the stability and efficiency of this algorithm.

Detection of ZAP70 Negative B-CLL Patients Using the Beckman Coulters Positional Parameter Technology and RPD (Research Population Data) Analysis.

B-CLL, the most common type of leukemia in adults, is heterogeneous with a varying clinical course ranging from indolent to aggressive disease. CLL patients with mutated Ig V(H) genes have a good prognosis while those with non-mutated Ig V(H) status and expression of the ZAP70 protein tyrosine kinase generally have aggressive disease and shorter survival. Testing for IgV(H) mutations is not routinely performed due to cost and ZAP70 testing is still technically difficult. As these tests remain generally inappropriate for B-CLL patient screening, we tested the capacity of the new Beckmann Coulter LH750 blood analyzers to provide additional morphometric information on the CLL cell population. These analyzers use a highly informative positional parameter technology - VCS (Volume, Conductivity, Scatter) technology, and automated RPD analysis which provide the Mean and Standard Deviation of Volume, Conductivity and Scatter (VCS) for each of the main WBC types (neutrophils, lymphocytes, monocytes and eosinophils), thereby enabling the detection of abnormal WBC populations associated with various hematological and non-hematological disorders. We attempted to determine if the RPD generated could differentiate between the ZAP70pos and ZAP70neg B-CLL subgroups as determined by high resolution quantitative ZAP70 flow cytometry analysis (1). This study included 30 newly diagnosed untreated CLL patients. CBC was performed on all samples using automated leukocyte differentials in the Beckmann-Coulter LH750. Statistical analysis was performed with Medcalc® 8.1.1.0. Results show that there was no correlation between the WBC number, ZAP70pos expression (found in 59% of the cases) and lymphocyte volume, scatter, or conductivity or SD of these parameters. However, differences in the automated morphology of the Zap70neg compared with Zap70pos CLL lymphocytes was detected. When compared to normal lymphocyte volume (85.8±14.5), the Lymphocyte Mean Volume (MLYV) was lower in the ZAP70neg samples (77.7±17.6) (p<0.05), while the ZAP70pos samples had increased volumes (87.5±15.8), similar to values reported in other myeloproliferative states. The conductivity of the ZAP70neg cells was reduced (110±15.0) below normal (117±11.5) (p=0.038), while the ZAP70pos cells had conductivity similar to the control group. Higher levels of lymphocyte apoptosis were clearly observed in the ZAP70neg samples by VCS. When using ROC (receiver operating curve analysis) to detect the potential ZAP70neg cases, the cut off proposed is MLYV < 76 with a sensitivity of 69.2% and a specificity of 70% AUC 0,650. Herein we propose an entirely new approach which may provide a novel diagnostic screening approach to enable identification of CLL patients who do not require further complex testing. This data is derived directly from the CBC of the Beckman-Coulter LH750 analyzers at no extra cost. As it will be necessary to analyze many more cases from different laboratories, an international working group has been formed in an attempt to confirm these early observations.