Multiphase Samples Research Articles

Thermal Stability and Tuning of Thermoelectric Properties of Ag1−xSb1+xTe2+x (0 ≤ x ≤ 0.4) Alloys

Introduction of nonstoichiometry to AgSbTe2-based materials is considered to be an effective way to tune thermoelectric properties similarly to extrinsic doping. To prove this postulate, a systematic physicochemical study of the Ag1−xSb1+xTe2+x alloys (0 ≤ x ≤ 0.4) was performed. In order to investigate the influence of the cooling rate after synthesis on phase composition and thermoelectric performance, slowly cooled and quenched Ag1−xSb1+xTe2+x alloys (x = 0; 0.1; 0.17; 0.19; 0.3; 0.4) were prepared. Single-phase material composed of the β phase (NaCl structure type) was obtained for the quenched x = 0.19 sample only. The other alloys must be regarded as multi-phase materials. The cooling rate affects the formation of the phases in the Ag-Sb-Te system and influences mainly electronic properties, carrier mobility and carrier concentration. The extremely low lattice thermal conductivity is an effect of the mosaic nanostructure. The maximal value of the figure of merit ZTmax = 1.2 is observed at 610 K for the slowly cooled multi-phase sample Ag0.9Sb1.1Te2.1. Thermoelectric properties are repeatedly reproducible up to 490 K.

Hybrid Trajectory Planning for Autonomous Driving in Highly Constrained Environments

In this paper, we introduce a novel and efficient hybrid trajectory planning method for autonomous driving in highly constrained environments. The contributions of this paper are fourfold. First, we present a trajectory planning framework that is able to handle geometry constraints, nonholonomic constraints, and dynamics constraints of cars in a humanlike and layered fashion and generate curvature-continuous, kinodynamically feasible, smooth, and collision-free trajectories in real time. Second, we present a derivative-free global path modification algorithm to extract high-order state information in free space for state sampling. Third, we extend the regular state-space sampling method widely used in on-road autonomous driving systems to a multi-phase deterministic state-space sampling method that is able to approximate complex maneuvers. Fourth, we improve collision checking accuracy and efficiency by using a different car footprint approximation strategy and a two-phase collision checking routine. A range of challenging simulation experiments show that the proposed method returns high-quality trajectories in real time and outperforms existing planners, such as hybrid A* and conjugate-gradient descent path smoother in terms of path quality, efficiency, and computation resources used.

Application of X-ray Diffraction and Electron Crystallography for Solving Complex Structure Problems.

All crystalline materials in nature, whether inorganic, organic, or biological, macroscopic or microscopic, have their own chemical and physical properties, which strongly depend on their atomic structures. Therefore, structure determination is extremely important in chemistry, physics, materials science, etc. In the past centuries, many techniques have been developed for structure determination. The most widely used one is X-ray crystallography (single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD)), and it remains the most important technique for structure determination of crystalline materials. Although SCXRD and PXRD are successful in many cases, a number of reasons limit their applications, such as SCXRD for nanosized crystals, intergrowth, and defects and PXRD for complex structures, multiphasic samples, impurities, peak overlaps, etc. Another most valuable technique for structure determination is electron crystallography (EC). With the electron as a probe, EC alone can also be used for structure determination, especially for crystals that are too small to be studied by SCXRD or too complex for PXRD. As electrons interact much more strongly with matter than X-rays do, both electron diffraction (ED) patterns and high-resolution transmission electron microscopy (HRTEM) images can be obtained from nanosized crystals. However, collecting a complete set of ED patterns or recording a good HRTEM image requires considerable expertise on the operation of electron microscopes and crystallography. The strong interactions between electrons and materials can also lead to dynamical effects and beam damage. These difficulties make structure determination from ED patterns and HRTEM images not straightforward. Recently, two three-dimensional (3D) electron diffraction techniques, automated electron diffraction tomography (ADT) and rotation electron diffraction (RED), have been developed, which perform the data collection in an automated manner. Although the dynamical effects in the newly developed 3D electron diffraction techniques (ADT, RED) are reduced significantly, for some structures there are still problems with obtaining an initial model because of beam damage. The X-ray diffraction and EC methods discussed above are both powerful techniques but have their own limitations. In many complicated cases, one technique alone is not enough to solve the crystal structure, and different techniques that supply complementary structural information have to support each other for the complete structure determination. In this Account, we provide a summary of the advantages and disadvantages of X-ray diffraction (PXRD and SCXRD) and EC (HRTEM and ED) for structure determination and include a review of applications of X-ray diffraction and EC for solving complex structure problems such as peak overlap, impurities, pseudosymmetry and twinning, disordered frameworks, locating guests, aperiodic structures, etc. Some of the latest advances in structure determination are also presented briefly, namely, revealing hydrogen positions by ED, protein crystal structure solution by 3D electron diffraction, and structure determination using an X-ray free electron laser (XFEL).

Local segregation versus irradiation effects in high-entropy alloys: Steady-state conditions in a driven system

We study order transitions and defect formation in a model high-entropy alloy (CuNiCoFe) under ion irradiation by means of molecular dynamics simulations. Using a hybrid Monte-Carlo/molecular dynamics scheme, a model alloy is generated which is thermodynamically stabilized by configurational entropy at elevated temperatures, but partly decomposes at lower temperatures by copper precipitation. Both the high-entropy and the multiphase sample are then subjected to simulated particle irradiation. The damage accumulation is analyzed and compared to an elemental Ni reference system. The results reveal that the high-entropy alloy—independent of the initial configuration—installs a certain fraction of short-range order even under particle irradiation. Moreover, the results provide evidence that defect accumulation is reduced in the high-entropy alloy. This is because the reduced mobility of point defects leads to a steady state of defect creation and annihilation. The lattice defects generated by irradiation are shown to act as sinks for Cu segregation.

Thermodynamic Parameters of Single‐ or Multi‐Band Superconductors Derived from Self‐Field Critical Currents

AbstractKey questions for any superconductor include: what is its maximum dissipation‐free electrical current (its ‘critical current') and can this be used to extract fundamental thermodynamic parameters? Present models focus on depinning of magnetic vortices and implicate materials engineering to maximise pinning performance. But recently we showed that the self‐field critical current for thin films is a universal property, independent of microstructure, controlled only by the penetration depth. Here, using an extended BCS‐like model, we calculate the penetration depth from the temperature dependence of the superconducting energy gap thus allowing us to fit self‐field critical current data. In this way we extract from the T‐dependent gap a set of key thermodynamic parameters, the ground‐state penetration depth, energy gap and jump in electronic specific heat. Our fits to 79 available data sets, from zinc nanowires to compressed sulphur hydride with critical temperatures of 0.65 to 203 K, respectively, are excellent and the extracted parameters agree well with reported bulk values. Samples include thin films, wires or nanowires of single‐ or multi‐band s‐wave and d‐wave superconductors of either type I or type II. For multiband or multiphase samples we accurately recover individual band contributions and phase fractions.

Generalized P-phased Regression Estimators with Single and Two Auxiliary Variables

Multiphase sampling has been the concept not being utilized is estimation of ratio and regression estimator widely. In the recent study we have proposed new dimension of sampling survey of estimations by proposing two generalized p-phase regression estimators with single and two auxiliary variables for estimating population mean. The proposed estimators are the generalized p-phase cases of Hanif et al (2015) and Hanif (2007) respectively. Both the estimators from which we took motivation are now special cases of our proposed estimators. We have derived unbiasedness, expression of Mean Square Errors along with family of estimators based upon p-phased generalization. We have derived expression of MSE in such a way that these expression can be used to obtained results for every phase we desire. By conducting empirical study on proposed estimators we have shown many situation in which MSE can be reduced by increasing number of phases. Hence, our study will open new horizon in the field of multiphase sampling where a lot of challenges are waiting to be resolved by proposing new estimators for phases above 2 nd phase.

Evaluating principal surrogate markers in vaccine trials in the presence of multiphase sampling.

This article focuses on the evaluation of vaccine-induced immune responses as principal surrogate markers for predicting a given vaccine's effect on the clinical endpoint of interest. To address the problem of missing potential outcomes under the principal surrogate framework, we can utilize baseline predictors of the immune biomarker(s) or vaccinate uninfected placebo recipients at the end of the trial and measure their immune biomarkers. Examples of good baseline predictors are baseline immune responses when subjects enrolled in the trial have been previously exposed to the same antigen, as in our motivating application of the Zostavax Efficacy and Safety Trial (ZEST). However, laboratory assays of these baseline predictors are expensive and therefore their subsampling among participants is commonly performed. In this article, we develop a methodology for estimating principal surrogate values in the presence of baseline predictor subsampling. Under a multiphase sampling framework, we propose a semiparametric pseudo-score estimator based on conditional likelihood and also develop several alternative semiparametric pseudo-score or estimated likelihood estimators. We derive corresponding asymptotic theories and analytic variance formulas for these estimators. Through extensive numeric studies, we demonstrate good finite sample performance of these estimators and the efficiency advantage of the proposed pseudo-score estimator in various sampling schemes. We illustrate the application of our proposed estimators using data from an immune biomarker study nested within the ZEST trial.

Statistical Description of Inhomogeneous Samples by Scanning Microwave Microscopy

A quantitative analysis of the dielectric properties of a multiphase sample using a scanning microwave microscope (SMM) is proposed. The method is demonstrated using inhomogeneous samples composed of a resin containing micrometric inclusions of a known ceramic material. The SMM suitable for this task employs relatively large tips (tens of micrometers in diameter). Additionally, in order to make the instrument more suitable for high-throughput analysis, an original design for rapid tip changes is implemented. Single-point measurements of dielectric constant at random locations on the sample were performed, leading to histograms of dielectric constant values. These are related to the dielectric constants of the two phases using Maxwell–Garnett effective medium theory, taking into account the volume-of-interaction in the sample beneath the tip.

A Low Nonlinearity, Missing-Code Free Time-to-Digital Converter Based on 28-nm FPGAs With Embedded Bin-Width Calibrations

This paper presents a low nonlinearity, missing-code free, time-to-digital converter (TDC) implemented in a 28-nm field programmable gate array (FPGA) device (Xilinx Virtex 7 XC7V690T) with novel direct bin-width calibrations. We combine the tuned tapped delay lines (TDLs) and a modified direct-histogram architecture to correct the nonuniformity originated from carry chains, and use a multiphase sampling structure to minimize the skews of clock routes. Results of code density tests show that the proposed TDC has much better linearity performances than previously published TDCs. Moreover, our TDC does not generate missing codes. For a single TDL, the differential nonlinearity (DNL) is within [−0.38, 0.87] LSB (the least significant bit: 10.5 ps) with $\sigma _{\mathrm {DNL}} = 0.20$ LSB, and the integral nonlinearity (INL) is within [−1.23, 1.02] LSB with $\sigma _{\mathrm {INL}} = 0.50$ LSB. Based on the modified direct-histogram architecture, a direct bin-width calibration method was implemented and verified in the FPGA. By implementing embedded bin-width calibrations, the histogram data of TDCs can be calibrated on the fly. After the calibration, the DNL $_{\mathrm {pk-pk}}$ (peak-to-peak DNL) and INL $_{\mathrm {pk-pk}}$ (peak-to-peak INL) can be reduced to 0.08 LSB with $\sigma _{\mathrm {DNL}} = 0.01$ and 0.13 LSB with $\sigma _{\mathrm {INL}} = 0.02$ LSB, respectively.

PENGARUH WORKPLACE WELL-BEING TERHADAP KINERJA GURU SD

Teacher performance is teacher perception on teacher work performance related to work quality, responsibility, honesty, cooperation and initiative. This study was conducted to obtain empirical evidence of the effect of good work on the performance of elementary school teachers in central Jakarta. This research uses quantitative approach. A sample of 79 certified teachers teaching elementary school in central Jakarta using multiphase sampling technique. How to use data by using questionnaire media for data retrieval. Respondents of this study are teachers of primary school certified in central Jakarta. The variable used is workplace well-being as independent variable, teacher performance as dependent variable. To determine the effect of workplace well-being, based on multiple regression analysis at 33.1% significant level it can be concluded whether the workplace well-being is significant enough to the performance of elementary school teachers.

Characterization of nanograined powder samples using the Rietveld method applied to electron diffraction ring patterns

A full-pattern fitting procedure based on the Rietveld method was applied to electron diffraction ring patterns of a two-phase system, exhibiting the co-presence of zinc sulfide (sphalerite) and zinc oxide (Wurtzite). Bright and dark field (DF) images reveal the presence of micrometric aggregates, composed of quasi-spherical nanosized crystallites. These conventional transmission electron microscopy imaging methods provide a general morphological characterization of the specimens although, in the present case, they are not suitable for a detailed characterization of the microstructural features of the analyzed samples. Owing to the overlap and broadening of the diffraction rings of the two phases, DF images cannot provide a satisfactory picture of the individual crystallites of each single phase. To overcome this limit, the mentioned Rietveld approach was applied to model the electron diffraction data. The crystalline domain size and relevant shapes for both phases were successfully evaluated using the proposed methodological approach. The excellent results obtained in the microstructural characterization of the nanostructured multiphase samples demonstrate the capability of this technique, that may represents a fully quantitative method for the routine characterization of crystalline nanomaterials.

Prevalence of hypertension and prehypertension in adolescence in Ahvaz, Iran

BackgroundHigh blood pressure is a risk factor for some disease like stroke, coronary heart disease, and renal failure. High blood pressure in children is an increasing health problem. ObjectivesThe aim of this study was to determine prevalence of hypertension and pre-hypertension age between 10 to 17 years old. Patients and methodsThis descriptive analytic study was conducted using multiphase sampling method in Ahvaz (Southwest of Iran). A questionnaire include: height, weight, and body mass index, systolic and diastolic blood pressures filled for each participant. Blood pressure was measured twice for each person. For the diagnosis of hypertension, the fourth report of the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents of the National Health Institute of United States was used. ResultsTotal participants of the study were 1707children and adolescents including 922 boys (54%) and 785 girls (46%). The prevalence of high blood pressure was 1.7% (2.5% in boys and 0.8%). The prevalence of pre-hypertension was 9%(7.6% in boys, 10.6% in girls). The mean systolic and diastolic blood pressures increased with increasing body mass index. ConclusionsThe prevalence of high blood pressure was found to be lower than other studies in our country. The prevalence of the high blood pressure in boys was significantly higher than girls. This study, like other studies showed high correlation between being overweight and an increase in systolic and diastolic blood pressure.

Desktop Tomography System using Planar ECT Device

Miniaturized planar electrical capacitance tomography (ECT) device is fabricated using microfabrication method to accommodate eight planar electrodes to carry out electrical capacitance measurement using tomography technique. Fluids within the detection chamber are detected by the difference of the permittivity parameters. Stagnant and hydrodynamic multiphase samples such as liquid-gas and liquid-liquid are tested. The eight-electrode planar array is fabricated on the copper plated printed circuit board (PCB) and the chamber is fabricated using polymer poly(dimethyl-siloxane) (PDMS). The images of the multiphase sample are reconstructing using Linear Back Projection algorithm (LBP). Computer interface software is developed to display the images of the fluid online. Experimental results show that the reconstructed images closely resemble with the composition of the multiphase sample within the detection chamber.

Study of the magnetic anisotropy of the multiphase samples of the ferrimagnets with hexagonal crystal structure by the method of ferromagnetic resonance

The influence of machining conditions in a planetary ball mill on the phase composition, structural and magnetic parameters of hexaferrite powders composition BaFe12O19 was investigated. The properties of powders vary greatly depending on the power density and the time of machining. Magnetocrystalline anisotropy of multiphase powders was studied by the method of ferromagnetic resonance. The effective field of magnetic anisotropy is reduced by more than two times, with decreasing particle size of ∼ 67 nm to ∼ 10 nm when the processing time equal to 10 minutes. The flow of mechanochemical reactions during grinding leads to the disintegration of the hexagonal crystal phase and the formation of the magnetite phase with a small value of the magnetocrystalline anisotropy field.

Measurement and correlation of the dielectric properties of a grape pomace extraction media. Effect of temperature and composition

Microwave assisted extraction has been proved to be a useful tool for the recovery of valuable compounds from natural products. However, little is known about the dielectric properties for mixtures of natural products and solvents. In this work, a semi-empirical model is proposed to calculate the dielectric properties of these systems. The variables considered were temperature, solvent composition and solid-liquid ratio. Grape pomace was used as the solid matrix and ethanol-water mixtures as the solvent. The experimental dielectric constant and loss factor of these multiphase solid-solvent samples were measured and compared to the proposed model. Loss factor values were taken under special consideration, since they were boosted by the release of ions from the solid (an increase between 9 and 83%). The model proposed here reproduces the dielectric properties of this multiphase media with an average deviation of 8.1% for the dielectric constant and of 24.8% for the loss factor.

Insights into the structural, microstructural and physical properties of multiphase powder mixtures

In recent years, research interests on structural and microstructural properties of materials have gained enormous impetus owing to their absolute necessity in many fields (e.g., chemistry, physics, synthetic and materials science). Herein, we present an insight into comprehensive ascertainment of the general structural, microstructural and physical properties of multiphase powder mixtures. We systematically explored the properties of the multiphase samples to disclose their structure and chemical composition features using a series of techniques, such as X-ray diffraction, and energy dispersive X-ray spectroscopy. The Rietveld approach based on structure and microstructure refinement analysis was adopted for precise determination of several microstructural parameters as well as phase contents of individual phases in the multiphase materials. The X-ray diffraction results confirms that the samples are multiphase and crystallize in the monoclinic baddeleyite structure with P 1 21/c 1 space group, orthorhombic mullite structure with P b a m space group, and cubic molybdenum structure with I m –3 m space group, respectively. The morphology features of the samples were observed by using scanning electron microscopy. The actual elemental distributions can be easily observed in energy dispersive X-ray spectrometry elemental mappings. To shed more light on the properties of the multiphase powder mixtures, their physical features (e.g., dislocation density, unit cell volume, X-ray density, porosity) were researched in detail. Moreover, the residual stresses of the multiphase samples were investigated by utilizing the sin2ψ approach.

MultiLaue: A Technique to Extract d-spacings from Laue XRD

doi:10.1017/S1431927616009764 Microsc. Microanal. 22 (Suppl 3), 2016 © Microscopy Society of America 2016 MultiLaue: A Technique to Extract d-spacings from Laue XRD Zack Gainsforth 1 , Matthew A. Marcus 2 , Nobumichi Tamura 2 and Andrew J. Westphal 1 University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, 91020, USA Lawrence Berkeley Laboratory, Advanced Light Source, Berkeley, CA, 91020, USA Broad spectrum X-ray Diffraction (XRD) is named Laue after Max von Laue, and is the original XRD technique [1]. Today, monochromatic XRD is more common because Bragg's equation allows determination of d-spacings where Laue does not. Laue still remains in use for single crystal systems because it can be used to make very accurate unit cell determinations as well as for strain and orientation mapping. A Laue technique which could provide unambiguous determination of lattice spacings, a la Bragg's equation would be a huge leap forward, especially for multiphase samples such as meteorites, interplanetary dust particles and some geological specimens. We introduce a new technique we call multiLaue which allows such determination. First an unfiltered Laue pattern is acquired. Then a filter is inserted between the radiation source and the sample – in this case a 100 um thick fused silica wafer – and a new Laue pattern is acquired. A shield protects the detector from radiation scattered off the filter. Low energy X-rays are more strongly absorbed by the filter than high energy X-rays so reflections excited by low energies are more attenuated relative to those excited by high energies. We developed a computer model simulating the process, and use it to quantitatively determine the X-ray energy exciting a reflection based on the reduction of intensity across a set of three filters (100, 200 and 300 micron fused silica). We tested multiLaue on a Si chip on beamline 12.3.2 at the Advanced Light Source synchrotron. The unfiltered pattern is shown in Figure 1. We analyzed 32 reflections (Table 1) and computed best fit energies. These are compared with energies based on indexation via the XMAS software [2]. The best fit energies matched well between 11 and 23 keV, with a mean relative error of 1.9% and a standard deviation of the error of 1.4%. This means we can compute d-spacings with an accuracy of 21 keV have large errors. Reflections < 11 keV have a harmonic contribution from the spectrum above 21 keV and also show large errors. Therefore, accurate characterization of the radiation source, and optics is crucially important to achieving high accuracy quantification.

Relationship between Self-Esteem and Psychological Hardiness in Adolescents: A Relation Design

Introduction: Self-esteem is highly important in terms of mental health and personality balance. Psychological hardiness is a general orientation toward self and the surrounding world. Purpose: This study has been done with the aim of investigating the relationship of self-esteem and psychological Hardiness in Adolescents. Method: This study with causal-comparative framework was done in domain of descriptive studies. Therefore eighty (N=70) persons from residents of region 2 and region 5 of Tehran city (ages of 18-35 with average age of 22.7) were selected by multiphasic cluster sampling. The method of data collection was through survey and to this aim two questionnaires of Psychological Hardiness (response rate=0.90) and self-esteem scale (response rate=0.91) were used. The data were analyzed by Pearson parametric correlation test and F-test. Moreover the qualitative data resulting from demographic evaluations were codified and analyzed by analysis instrument of qualitative data i.e. Atlas.ti-5.2. Findings: the findings resulted from data analysis represented that there is significant relationship between spiritual intelligence and marital satisfaction (P&lt;0.05). Conclusion: the findings of this research can be relevant to mainstream research and is hoped to help find new windows of discovery and development.

Forgiveness and Its Relationship with Marital Satisfaction: A Sectional Study

Introduction: forgiveness is one of the new issues in the scope of family treatment that in recent decades entered the scopes of psychology and family consultation. Purpose: the present study has done with aim of investigating the relationship of forgiveness index with marital satisfaction. Method: this study with a causal-comparative framework was done in domain of descriptive studies. To this aim eighty couples (N=160) from residents of region 2 and region 5 of Tehran city (age range of 18-31 with average age of 20.6) were selected by multiphasic cluster sampling. The data collected through survey and to this aim two questionnaires of measurement of couples’ impunity (response rate=89%) and marital satisfaction questionnaire (response rate=91%) were used. The data were analyzed through Pearson parametric correlation test and t-test. Moreover the qualitative data resulting from demographic evaluations were codified and were analyzed by analysis instrument of qualitative data i.e. Atlas.ti-5.2. Findings: the findings resulted from data analysis represented that there is significant relationship between two indices of forgiveness and marital satisfaction (P&lt;0.05). Besides, the forgiveness index determined 0.40 of variance changes in marital satisfaction variable. Conclusion: the respective findings while including applicable implications can be of high importance in prevention and intervention perspective.

Phase transformations during processing and in vitro degradation of porous calcium polyphosphates.

A 2-Step sinter/anneal treatment has been reported previously for forming porous CPP as biodegradable bone substitutes[9]. During the 2-Step annealing treatment, the heat treatment used strongly affected the rate of CPP degradation in vitro. In the present study, x-ray diffraction and (31)P solid state nuclear magnetic resonance were used to determine the phases that formed using different heat treating processes. The effect of in vitro degradation (in PBS at 37°C, pH 7.1 or 4.5) was also studied. During CPP preparation, β-CPP and γ-CPP were identified in powders formed from a calcium monobasic monohydrate precursor after an initial calcining treatment (10h at 500°C). Melting of this CPP powder (at 1100°C), quenching and grinding formed amorphous CPP powders. Annealing powders at 585°C (Step-1) resulted in rapid sintering to form amorphous porous CPP. Continued annealing to 650°C resulted in crystallization to form a multi-phase structure of β-CPP primarily plus lesser amounts of α-CPP, calcium ultra-phosphates and retained amorphous CPP. Annealing above 720°C and up to 950°C transformed this to β-CPP phase. In vitro degradation of the 585°C (Step-1 only) and 650°C Step-2 annealed multi-phase samples occurred significantly faster than the β-CPP samples formed by Step-2 annealing at or above 720°C. This faster degradation was attributable to preferential degradation of thermodynamically less stable phases that formed in samples annealed at 650°C (i.e. α-phase, ultra-phosphate and amorphous CPP). Degradation in lower pH solutions significantly increased degradation rates of the 585 and 650°C annealed samples but had no significant effect on the β-CPP samples.