Method For Determination Of Size Research Articles

Microbubbles decorated with dendronized magnetic nanoparticles for biomedical imaging: effective stabilization via fluorous interactions.

Dendrons fitted with three oligo(ethylene glycol) (OEG) chains, one of which contains a fluorinated or hydrogenated end group and bears a bisphosphonate polar head (CnX2n+1OEG8Den, X = F or H; n = 2 or 4), were synthesized and grafted on the surface of iron oxide nanoparticles (IONPs) for microbubble-mediated imaging and therapeutic purposes. The size and stability of the dendronized IONPs (IONP@CnX2n+1OEG8Den) in aqueous dispersions were monitored by dynamic light scattering. The investigation of the spontaneous adsorption of IONP@CnX2n+1OEG8Den at the interface between air or air saturated with perfluorohexane and an aqueous phase establishes that exposure to the fluorocarbon gas markedly increases the rate of adsorption of the dendronized IONPs to the gas/water interface and decreases the equilibrium interfacial tension. This suggests that fluorous interactions are at play between the supernatant fluorocarbon gas and the fluorinated end groups of the dendrons. Furthermore, small perfluorohexane-stabilized microbubbles (MBs) with a dipalmitoylphosphatidylcholine (DPPC) shell that incorporates IONP@CnX2n+1OEG8Den (DPPC/Fe molar ratio 28:1) were prepared and subsequently characterized using both optical microscopy and an acoustical method of size determination. The dendrons fitted with fluorinated end groups lead to smaller and more stable MBs than those fitted with hydrogenated groups. The most effective result is already obtained with C2F5, for which MBs of ≈1.0 μm in radius reach a half-life of ≈6.0 h. An atomic force microscopy investigation of spin-coated mixed films of DPPC/IONP@C2X5OEG8Den combinations (molar ratio 28:1) shows that the IONPs grafted with the fluorinated dendrons are located within the phospholipid film, while those grafted with the hydrocarbon dendrons are located at the surface of the phospholipid film.

P997Improving left atrial appendage occluder size determination by using 3-dimensional printing model of the left atrial appendage

Abstract Introduction Given the complexity of left atrial appendage (LAA) structure, current 2D based LAA occluder (LAAO) size prediction system using transesophageal echocardiography (TEE) has limitations. Objective To assess the accuracy of LAAO size determination method by implantation simulation using a 3D printed model compared with a conventional method based on TEE. Methods We retrospectively reviewed 57 cases with percutaneous LAAO using Amplatzer Cardiac Plug and Amulet from 2014 to 2018. We excluded cases without cardiac CT (21 cases) or with peri-device leakage or inappropriate position of the device on six months follow up TEE (6 cases), or with paroxysmal atrial fibrillation (2 cases). We finally included 28 cases with anatomically and physiologically properly implanted LAAO, using the final size of the implanted devices as a standard for the size prediction accuracy. We generated 3D printing model from cardiac CT images. LAAO size was determined with device implantation simulation using 3D printing model and occluder devices (Figure C), and conventional 2D TEE measurements by two experienced cardiologists who were blinded to the size of the finally implanted device. Results The accuracy in size of 3D printed left atrium (LA) models, compared with CT image sources, were validated by measuring the distance between artifacts which were intentionally implanted to LA model during image processing. There was minimal bias (−0.11 mm) between 3D images and printed LA models (Figure A). As plotted in Figure B, LAAO sizing by implantation simulation with 3D printing model showed excellent agreement with actually implanted LAAO size (r=0.927; bias=0.7±2.5), while LAAO sizing by 2D TEE measurements remained poor (r=0.544; bias 2.3±6.7). Conclusions LAAO size determination by using 3D printing model of LAA showed excellent accuracy. A prospective study to evaluate the clinical utility of this method should be done in future.

Combination of a rotating tube sample divider and dynamic image analysis for continuous on-line determination of granule size distribution

The granule size distribution is a critical quality attribute of granules. It has a great impact on further packaging or processing. Due to increasing interest in continuous manufacturing techniques, it is of high interest to develop an in-line or on-line tool to monitor the granule size distribution. However, development of an in-line measurement tool for granule size distribution was challenging since large throughput and inhomogeneous product stream are limiting factors for current particle size analyzers. In this study, continuous sampling was tested in conjunction to a continuous on-line method of size determination using dynamic image analysis. A rotating tube sample divider was used to split previously compacted material in representative samples at different ratios and the sample was directly conveyed to the particle size analyzer where the granule size distribution was determined. The method was tested for different granule sizes to determine limits of detection and its ability to detect these changes immediately, as this enables real-time monitoring of the process. This research is the base for development of control tools concerning the granule size distributions for continuous granulation processes.

Research on temperature distribution law around crack using the moving mode of eddy current thermography

Eddy current thermography (ECT) plays an important role in the field of nondestructive testing (NDT). In this study, a moving detection mode of ECT is used for crack detection and the temperature distribution near the crack in this mode is studied. Firstly, the numerical simulation is used to analyze the eddy current distribution on the specimen surface. And then the experimental studies are carried out and thermal images are obtained in the experiments. The surface temperature distribution of the specimen is analyzed, and the fitted curve of the temperature decline trend is given. The curve is helpful to determine the best detection area. The temperature distribution characteristics near the crack are analyzed and the position of the largest temperature difference on the specimen surface is determined. Finally, a new method for determination of crack opening size based on edge detection technology is proposed, and the size of the crack opening is obtained.

Part 1: Physicochemical characterization of bevacizumab in undiluted 25 mg/mL drug product solutions: Comparison of originator with a biosimilar candidate

The biosimilarity assessment of the physicochemical properties of high-concentration biopharmaceuticals is usually performed with measurements on diluted solutions, at concentrations below 1 mg/mL. In this study 13 orthogonal, spectroscopy and particle size determination methods were used to characterize the structure and aggregation of undiluted, 25 mg/mL bevacizumab drug products Avastin® manufactured in the USA and in Europe, and ABX-BEV, a bevacizumab biosimilar candidate produced by Apobiologix Inc. Secondary structure, conformation and the potential occurrence of chemical degradation of the monoclonal antibodies were characterized and compared using infrared spectroscopy, intrinsic fluorescence and ANS fluorescence spectroscopy. Protein aggregation and particulate matter in the monoclonal antibody solutions were compared using UV-Vis absorbance, 90° light-scattering, nanoparticle tracking analysis, Nile red fluorescence microscopy, particle flow imaging, ultrasound resonance technology and a new scanner-based method that visualizes protein aggregates inside unopened vials. A data wheel representation was used to plot in one figure the results from the multiple analytical methods and to highlight differences between samples. The 25 mg/mL Avastin® drug product is stored at 2–8 °C during its 2-year shelf life. After a thermal stress of 4 weeks at 40 °C the ABX-BEV solution was turbid, containing particles of 20–100 μm diameter, accompanied by strong changes in antibody structural properties. Characterization of unstressed samples stored at 2–8 °C showed that the physicochemical properties of bevacizumab in ABX-BEV and the two originator drug products were similar, the observed differences between the originators being in the same range as those between ABX-BEV and the originator. To investigate the similarity of the antibodies under stress conditions, a freeze-thaw study was performed. Although freeze-thawing of bevacizumab products is prohibited by the package insert, after two freeze-thaw cycles (24 °C to -80 °C) small changes in the structural and aggregation properties of bevacizumab were observed, changes that were similar for the originator and ABX-BEV. Our study showed a good similarity of the investigated physicochemical properties of bevacizumab in originator and ABX-BEV products. It also provides an analytical approach, based on orthogonal methods, to compare high-concentration formulations of monoclonal antibodies.

Quasi-static analysis of mixed-mode crack propagation using the meshless local Petrov–Galerkin method

The efficiency of classical truly meshless local Petrov–Galerkin method with linear test function approximation in the crack growth problems of complex configurations is investigated in this article. Several unique and multiple (two) cracks are examined to show the accuracy of the proposed meshfree method by comparing the crack path with boundary element, finite element, element-free Galerkin and experimental results. Crack propagation under both mechanical and thermal loads and also mode I and mixed-mode conditions are evaluated. Effect of the functionality of material properties on crack paths and sensitivity of crack growth to boundary conditions are investigated. Classical maximum circumferential stress criterion is employed into the formulation of the MLPG method to predict crack growth direction. Despite the common numerical studies, a simple and straightforward automatic increment size determination method is introduced and implemented in the MLPG method. Besides, regular domain point distribution in the vicinity of the crack tip without the increased density of points is used. Various test problems show the computational accuracy and applicability of this method to linear elastic fracture mechanics problems.

Location and size determination method of SFCLs in multi‐terminal VSC‐HVDC using iterative current reduction ranking

Superconducting fault current limiter (SFCL) is a promising technology to suppress fault current in multi-terminal VSC-HVDC. However, the location and size of SFCLs determination have become a problem to be studied. This study proposes a location and size determination method of SFCLs in multi-terminal VSC-HVDC. In the proposed method, the current reduction ranking is developed to quantify the current limiting effect, and iterative process is utilised to deal with the non-linear characteristics of current reduction. With the iterative current reduction ranking, the location and size could be determined collaboratively under mathematical guidance, ensuring the optimality of current limiting effect. Fast calculation of current reduction is investigated to accelerate the determination process. Finally, the effectiveness and feasibility of the proposed method are validated in a four-terminal VSC-HVDC.

Development and Validation of New Analytical Method for the Determination of Particle Size Distribution in Glimepiride Using Laser Based Particle Size Analyzer

Particle size is a key factor for modern drug quality since it affects the bioavailability and dissolution profile of the drug product. Study for Particle size is helpful to optimize drug product development process and improve the quality of drugs. In Order to determine the particle size of Glimepiride a novel and accurate Particle size determination method has been developed for the determination of particle size distribution of Glimepiride was described in this paper. This method has shown good reproducible results. By using water as dispersant wet method is developed and validated as per International conference on Harmonization guidelines (Q2 (R1)) and found out robust and reproducible with % RSD of d (10), d (50) and d (90) values found within acceptance limit ranges from 6.05% to 21.84% for d(0.1), 3.04% to 9.87% for d(0.5) and 4.69% to 14.32% for d(0.9) in validation. The described method is accurate and validated and successfully applied for the determination of particle size distribution of Glimepiride. Particle size method is discussed in detail to ensure in-depth understanding of particle size distribution and particle size method performance during lifetime of the product.

Perceived Influence of Students’ Demographic Variables on Their Access to Financial Aids in Public Universities in Rivers State, Nigeria

The paper investigated the perceived influence of students’ demographic variables on their access to financial aids in public Universities in Rivers State, Nigeria. Six questions were formulated to guide the study and five hypotheses tested at 0.05 level of significance. The design adopted for the study was an analytical survey. The population of the study included 78, 216 students (34,997 male and 43,219 female) in the three public Universities in Rivers State. The sample of the study covered 791 students (Male= 395 and Female= 396) selected through the random sampling technique while Taro Yamane method of sample size determination was used for determining the sample size. The instruments used for collecting responses from students were questionnaire and a ten items interview schedule. The research questions were answered using frequency, percentage and cumulative percentage. Findings of the study revealed that students’ demographic variables have an influence on their access to financial aids in public Universities in Rivers State, Nigeria. The implication of this is that the government’s expenditure on education will continue to increase in the absence of these alternative financial aids in the public Universities in Rivers State, Nigeria.

A Comparison and Case Study on Sample Size Determination Methods in Discriminant Analysis with Binary Response Variables

A Comparison and Case Study on Sample Size Determination Methods in Discriminant Analysis with Binary Response Variables

Method for grain size determination in carbon steels based on the ultimate opening

To understand mechanical properties in materials, grain size determination plays a fundamental role. Although, several automatic techniques for the determination of grain size have been introduced, nowadays a major drawback is associated with the quality of the images. The present work is focused on a novel image processing methodology for grain size determination which permits an accurate grain size determination even for poor quality images. This methodology is based on the watershed-plus-marker approach for segmenting the images. In this technique, the key to achieving a good segmentation is the detection of a set of markers of the regions of interest. Thus, our study focuses on the selection of markers signaling each grain. The method for selecting the markers is based on an improved associate function of the ultimate opening. To remove the undesirable regions a filtering process of this function is proposed to finally find the set of markers.

Representative volume element size determination for viscoplastic properties in polycrystalline materials

The size of representative volume element (RVE) for 3D polycrystalline material is investigated. A statistical RVE size determination method is applied to a Voronoi tessellation-based pure copper microstructure. The definition of RVE has remained problematic in the literature for properties related to nonlinear viscoplastic behavior, e.g. apparent viscoplastic parameter, intrinsic plastic dissipation. Computational homogenization for elastic and plastic properties is performed within a crystal plasticity finite element framework, over many realizations of the stochastic microstructural model, using periodic boundary conditions. The generated data undergoes statistical treatment, from which RVE sizes are obtained. The method used for determining RVE sizes was found to be operational, even for viscoplasticity. The microscale analysis of the full-field simulation results reveals microstructure-relate heterogeneities which shed new light on the problem of RVE size determination for nonlinear properties.

X-RAY DIFFRACTION METHOD FOR DETERMINATION OF SIZES AND STRUCTURAL CHARACTERISTICS OF NANOGRAPHITES IN ACTIVATED CARBON MATERIALS

The method for determination of sizes and structural characteristics of nanographites in activated carbon fibers (ACFs) by analyzing their experimental X-ray diffraction profiles has been developed in the paper. It uses the curves of X‑ray scattering calculated for the set of nanographites consisting of benzene- and phenalene-bazed nanographenes of various sizes, which interatomic and interlayer distances depend on the number of atoms in layer. The developed method can be also applied to analysis of the X-ray diffraction profiles of other nanocrystalline graphite structures. The data acquired by the method agree with results of Raman spectroscopy and small-angle X-ray scattering on ACFs structure motives.

More accurate than MRI measurement of tumor size in breast cancer by using the peri-tumoral halo uptake layer method of the 18F-FDG PET/CT scan.

To evaluate the reliability of a method using the peri-tumoral halo layer (PHL) for assessing tumor size in breast cancer patients on the fluorine-18-fluorodeoxy glucose positron emission tomography/computed tomography (18F-FDG PET/CT) scan compared to MRI and pathology. Among 121 patients with breast cancer who underwent both 18F-FDG PET/CT and MRI between March 2013 and June 2016, 59 patients were included in this study. Exclusion criteria were as follows: history of neoadjuvant therapy, history of pre-operative mammotome, insufficient pathologic/radiologic size report, clustered tumor, positive tumor resection margin, 18F-FDG non-avid tumor. The PHL was examined by two nuclear medicine physicians. Tumor sizes (longest diameters) on 18F-FDG PET/CT were estimated using margins defined as the inner line of the PHL. Pathologic tumor sizes were utilized as reference standards. The PHL of each tumor was most commonly designated as the 20%-30% band of the maximum standardized uptake value (SUVmax) it exhibited an inverse correlation with tumor SUVmax. Tumor size on 18F-FDG PET/CT showed a more linear correlation with pathology than that on MRI (r2=0.91 vs 0.65). In Bland-Altman analysis, 18F-FDG PET/CT showed significantly lower bias in size difference relative to pathology, compared with MRI (0.6±9.6cm vs. -1.9±17.3cm). Fluorine-18-FDG PET/CT showed more accurate T staging with pathology, especially in T3 cases, than MRI. A method of tumor size determination, using PHL on 18F-FDG PET/CT, showed more linear relationship and smaller size differences with pathology than MRI (average 0.6 vs. 1.9cm). It provides sufficient reliability and reproducibility for measuring tumor size in breast cancer.

Extension of the thermal porosimetry method to high gas pressure for nanoporosimetry estimation.

Standard pore size determination methods like mercury porosimetry, nitrogen sorption, microscopy, or X-ray tomography are not suited to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization has been developed in a previous study. This method has been used with air pressure varying from 10-1 to 105 Pa for materials having a thermal conductivity less than 0.05 W m-1 K-1 at atmospheric pressure. It enables the estimation of pore size distribution between 100 nm and 1 mm. In this paper, we present a new experimental device enabling thermal conductivity measurement under gas pressure up to 106 Pa, enabling the estimation of the volume fraction of pores having a 10 nm diameter. It is also demonstrated that the main thermal conductivity models (parallel, series, Maxwell, Bruggeman, self-consistent) lead to the same estimation of the pore size distribution as the extended parallel model (EPM) presented in this paper and then used to process the experimental data. Three materials with thermal conductivities at atmospheric pressure ranging from 0.014 W m-1 K-1 to 0.04 W m-1 K-1 are studied. The thermal conductivity measurement results obtained with the three materials are presented, and the corresponding pore size distributions between 10 nm and 1 mm are presented and discussed.

Sample size determination for mediation analysis of longitudinal data

BackgroundSample size planning for longitudinal data is crucial when designing mediation studies because sufficient statistical power is not only required in grant applications and peer-reviewed publications, but is essential to reliable research results. However, sample size determination is not straightforward for mediation analysis of longitudinal design.MethodsTo facilitate planning the sample size for longitudinal mediation studies with a multilevel mediation model, this article provides the sample size required to achieve 80% power by simulations under various sizes of the mediation effect, within-subject correlations and numbers of repeated measures. The sample size calculation is based on three commonly used mediation tests: Sobel’s method, distribution of product method and the bootstrap method.ResultsAmong the three methods of testing the mediation effects, Sobel’s method required the largest sample size to achieve 80% power. Bootstrapping and the distribution of the product method performed similarly and were more powerful than Sobel’s method, as reflected by the relatively smaller sample sizes. For all three methods, the sample size required to achieve 80% power depended on the value of the ICC (i.e., within-subject correlation). A larger value of ICC typically required a larger sample size to achieve 80% power. Simulation results also illustrated the advantage of the longitudinal study design. The sample size tables for most encountered scenarios in practice have also been published for convenient use.ConclusionsExtensive simulations study showed that the distribution of the product method and bootstrapping method have superior performance to the Sobel’s method, but the product method was recommended to use in practice in terms of less computation time load compared to the bootstrapping method. A R package has been developed for the product method of sample size determination in mediation longitudinal study design.

Methods of sampling and sample size determination of a comprehensive integrated community-based interventional trial: Isfahan Healthy Heart Program.

BACKGROUNDThe aim of this study was describing the sampling methods and sample size of the Isfahan Healthy Heart Program (IHHP) and its sub-studies in focus.METHODSThe IHHP was carried out between 2000 and 2007 in urban and rural areas in 3 districts, namely Isfahan and Najafabad (as the intervention areas), and Arak (as the reference area), Iran. It consisted of the 3 phases of baseline surveys during 2000-2001, interventions between 2002 and 2005, and post-intervention surveys during 2006-2007 on 4 target groups (adults, health professionals, cardiac patients, children, and adolescents). During 2002 to 2005, 4 evaluation studies were conducted to evaluate short-term results. An ongoing cohort study entitled the Isfahan Cohort Study was performed on those aged ≥ 35 years at baseline in 2001 to access the risk of cardiovascular disease (CVD) occurrence.RESULTSUsing stratified random cluster methods, 12514, 5891, 4793, 6096, 3012, and 9572 adults and 1946, 1999, 1427, 1223, 389, and 1992 adolescents were chosen in the 1st to 3rd phases. Furthermore, simple random sampling was used for selecting 923, 694, 1000, and 2015 health professionals and 814, 452, 420, and 502 cardiac patients. A multistage sampling method was adopted for the collection of samples from parents of preschoolers and primary school children aged 2-10 years, adolescents’ parents, and some teachers. A prospective cohort study was started on 6504 eligible individuals.CONCLUSIONThe IHHP, as a comprehensive community-based interventional trial in Iran, among the few population-based studies around the world, has reasonable sampling methods and sample size.

Factors of Production and Their Effects on the Contributions of Sole Proprietorship Businesses to the Economic Development of Developing Countries: The Case of Ghana

Unemployment is seen as a big problem for both developed and developing countries Simmons, (2016). It (unemployment) is typically understood as the condition of not having a paying job even though the person is willing to work. For Romero, (2014) governments alone cannot solve unemployment problem in a given country so individuals, groups or families should set up businesses to complement governments' efforts. The study investigated the factors that influence sole proprietorship business in Ghana and how those factors affect their contributions to the economy. To carry out the study the researchers relied on three research questions which included factors that influence sole proprietorship businesses in Ghana, how the activities of sole proprietors are monitored in Ghana among others. A descriptive survey design which aims at obtaining information concerning the current status of a phenomena to describe ‘what exists' with respect to variables or conditions in a situation was used. Questionnaires, interviews and observation guides were the instruments used for the study. Both Nwana (2005) and Fisher et al (2008) methods of sample size determination were used for the study. One thousand eight hundred and fifty-four respondents constituted the sample size for the study. The study disclosed that inadequacies in factors of production negatively affected the contributions of sole proprietors to the Ghanaian economy.

Bayesian sample size determination for cost-effectiveness studies with censored data.

Cost-effectiveness models are commonly utilized to determine the combined clinical and economic impact of one treatment compared to another. However, most methods for sample size determination of cost-effectiveness studies assume fully observed costs and effectiveness outcomes, which presents challenges for survival-based studies in which censoring exists. We propose a Bayesian method for the design and analysis of cost-effectiveness data in which costs and effectiveness may be censored, and the sample size is approximated for both power and assurance. We explore two parametric models and demonstrate the flexibility of the approach to accommodate a variety of modifications to study assumptions.

A universal parameterized gradient-based method for photon beam field size determination.

To propose a universal, parameterized gradient-based method (PGM) for radiation field size determination. The PGM locates the beam profile's edge by parameterizing its penumbra region with a modified sigmoid function where the inflection point can be determined in a closed form. The parametrization was validated with filter-flattened (FF), flattening-filter-free (FFF) and wedged profiles measured on two Elekta linac models (Synergy and Versa HD). Gamma analysis with the delta dose function set to zero was used to quantitatively assess the parameterization accuracy. Field sizes of FF beams were calculated with the PGM and the full width at half maximum (FWHM) methods for comparison. To assess the consistency of the PGM and the FWHM method with geometric scaling across different depths, the calculated field size at a reference depth was scaled to other depths and compared with the field sizes calculated from the measured profiles. The method was also validated against a maximum-slope method (MSM) with wedge and FFF profiles. We also evaluated the robustness of the three methods with respect to measurement noise, varying scanning step sizes, detector characteristics, and beam energy/modality. Small distance-to-agreement (0.02±0.02mm) between the measured and parameterized penumbra region was observed for all profiles. The differences between the field sizes calculated with the FWHM method and the PGM were consistent (0.9±0.3mm), with the FWHM method yielding larger values. With geometrical scaling, the PGM and the FWHM method produced maximum differences of 0.26 and 1.16mm, respectively. For wedge and FFF beams, the mean differences relative to FF fields were 0.15±0.09mm and 0.57±0.91mm for the PGM and the MSM, respectively. The PGM was also found to produce more consistent results than the FWHM method and the MSM when measurement noise, scanning step size, detector characteristics, and beam energy/modality changed. The proposed PGM is universally applicable to all beam modalities (FF, wedge and FFF) for accurate field size determination. Compared to the FWHM and the MSM, it is more robust to variations in measurement condition and detection system.