Effect Of Homogenization Treatment Research Articles

Unraveling the Effect of Homogenization Treatment on Decomposition of Austenite and Mechanical Properties of Low‐Alloyed TRIP Steel

The homogenization treatment is shown to have profound effects on the decomposition of austenite, suppression of microstructural banding, and work‐hardening capacity of transformation‐induced plasticity (TRIP) steels. Due to the similarity in the activity of carbon in different parts of the parent austenite phase and its extremely coarse grain size, a nearly full homogenization annealing results in the massive‐like transformation during subsequent decomposition of austenite at slow cooling rates.

Effect of homogenization treatment on microstructure and mechanical properties of DC cast 7X50 aluminum alloy

The evolution of the eutectic structures in the as-cast and homogenized 7X50 aluminum alloys was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), differential scanning calorimetry(DSC), X-ray diffraction(XRD) and tensile test. The results show that the main phases are S(Al2CuMg), T(Al2Mg3Zn3) and MgZn2, with a small amount of Al7Cu2Fe and Al3Zr in the as-cast 7X50 alloy. The volume fraction of the dendritic-network structure and residual phase decreases gradually during the homogenization. After homogenization at 470 °C for 24 h and then 482 °C for 12 h, the T(Al2Mg3Zn3) phase disappears and minimal S(Al2CuMg) phase remains, while almost no change has happened for Al7Cu2Fe. There is a strong endothermic peak at 477.8 °C in the DSC curve of as-cast alloy. A new endothermic peak appears at 487.5 °C for the sample homogenized at 470 °C for 1 h. However, this endothermic peak disappears after being homogenized at 482 °C for 24 h. The T(Al2Mg3Zn3) phase cannot be observed by XRD, which is consistent with that T phase is the associated one of S(Al2CuMg) phase and MgZn2 phase. The volume fraction of recrystallized grains is substantially less in the plate with pre-homogenization treatment. The strength and fracture toughness of the plate with pre-homogenization treatment are about 15 MPa and 3.3 MPa·m½ higher than those of the material with conventional homogenization treatment.

On the distribution of exchange rate regime treatment effects on international trade

This paper provides evidence of heterogeneous treatment effects on trade for six different types of exchange rate regime transitions, utilizing data on 218,643 country-pair-year observations all together. Previous research mainly focused on the currency union effect on trade and widely assumed that country-pairs with identical observable characteristics receive the same effect. We test the hypothesis of a homogeneous treatment effect empirically and find substantive statistical support for the presence of effect heterogeneity. Moreover, we characterize the probability distribution of effect heterogeneity among observationally equivalent country-pairs by way of a random coefficients model. We estimate selected features of the empirical distributions of the treatment effects for each of the six different types of exchange rate regime transitions under two different sets of assumptions about the probability distribution of effect heterogeneity. Our findings suggest that the immediate effects on trade from switching to an exchange rate regime different from the one in the outset have wide waists and exhibit large positive extreme values. We estimate the probability of two countries to experience an immediate positive effect on the growth of bilateral trade due to the adoption of any new exchange rate regime (tighter or not) to be approximately one-half.

Effect of homogenization treatment and silicon content on the microstructure and hot workability of dilute Al–Fe–Si alloys

Abstract The effect of the homogenization treatment on the microstructure and hot workability of two dilute Al–Fe–Si alloys was investigated using optical microscopy, SEM, EBSD, electrical conductivity measurements and hot compression testing. Homogenization promoted the phase transformation from the metastable AlmFe or α-AlFeSi phase to the Al3Fe equilibrium phase and induced a significant change in solute levels in the solid solution. The AlmFe dissolved and transformed completely at 550 °C in both alloys. The α-AlFeSi was transformed at 590 °C in the low Si alloy (Al–0.3Fe–0.1Si), whereas it began to decompose and transform to Al3Fe at 630 °C in the high Si alloy (Al–0.3Fe–0.25Si). The flow stress behavior of dilute Al-Fe-Si alloys was primarily controlled by the amount of Fe and Si in the solid solution. Homogenization at 550 °C significantly reduced the solid solution levels due to the elimination of the supersaturation originating from the cast ingot and produced the lowest flow stress under all of the deformation conditions studied. An increase in the homogenization temperature from 550 to 630 °C increased the flow stress by 10–23% and 15–45% for the low Si alloy and the high Si alloy, respectively, over the range of deformation conditions examined. An increase in the silicon level from 0.10% to 0.25% raised the overall flow stresses by 4–11% due to increased solute levels for given homogenization conditions.

Comparison of Statistical Analysis Plans in Randomize-All Phase III Trials with a Predictive Biomarker

When there are no compelling biologic or early trial data for a candidate predictive biomarker with regard to its ability to predict the effect of an anticancer treatment at the initiation of definitive phase III trials, it is generally reasonable to include all patients as eligible for randomization but to plan for a prospective subgroup analysis based on the biomarker. We assessed such statistical analysis plans, fixed-sequence, fallback, and treatment-by-biomarker interaction approaches, in terms of the probability of asserting treatment efficacy for either the overall patient population or a biomarker-positive subpopulation of patients. If there was some evidence that the treatment would work better in the biomarker-positive subgroup than the biomarker-negative subgroup, then the fixed-sequence approaches would be favored, whereas if evidence was weak that there would be much difference in responsiveness between the two subgroups, then the fallback approach would be favored. If there was substantial uncertainty in the difference in treatment effects between the two subgroups, the treatment-by-biomarker interaction approach could be a reasonable choice as this approach generally provided a high probability of asserting treatment efficacy for the right patient population under homogeneous treatment effects and a qualitative interaction over biomarker-based subgroups. Clin Cancer Res; 20(11); 2820-30. ©2014 AACR.

Influence of Homogenization Treatment on Electrochemical Behavior of the Mg-0.8wt%Ga-0.8wt%In Anode Materials

The effects of homogenization treatment on the electrochemical corrosion behavior of Mg-0.8wt%Ga-0.8wt%In anode materials were investigated by the polarization and galvanostatic curves tests. The scanning electron micrographs of the secondary phase after heat treatment and the corroded surface of the specimens were observed. The corrosion product of the Mg-0.8wt%Ga-0.8wt%In alloy was determined by X-ray diffraction. The results show that the intergranular compound dissolved in the Mg matrix in the Mg-0.8wt%Ga-0.8wt%In after homogenizing at 673K for 24h. The least corrosion current density, 0.029mA/cm2, appeared in this specimen due to the least corrosion driving force. The corrosion of the Mg-0.8wt%Ga-0.8wt%In alloy in a 3.5% NaCl solution was generous corrosion and pitting attack. The corrosion product has been found to be mainly Mg (OH)2.

Effect of homogenization treatment on the fracture behaviour of silicon nitride/graphene nanoplatelets composites

Abstract Si 3 N 4 based composites with 7 wt.% of graphene nanoplatelets (GNPs) were prepared using different homogenization methods. Si 3 N 4 /GNPs powder mixtures were dispersed in isopropanol and homogenized by attritor milling, ball milling or planetary ball milling. The ball milling technique was also used for the homogenization of Si 3 N 4 /GNPs mixture in dry state. Fractography analysis was carried out in order to assess the individual homogenization treatment. Depending on the homogenization methods, the size of the processing flaws varied from 20 μm up to 400 μm. The agglomeration of the GNPs and the residual porosity were found as the most frequently observed types of the critical flaws. The planetary ball milling with previous ultrasonication of GNPs in isopropanol was found to be the most promising homogenization technique, resulting in the composites with the highest bending strength (average value is 740 MPa) and the lowest average size of the processing flaws (around 20 μm).

Effects of homogenization treatment on the microstructure and mechanical properties of Mg–8Li–3Al–Y alloy

Abstract The effects of homogenization treatment of Mg–8Li–3Al–Y alloy were investigated by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and universal testing machine. The experiment results indicated that there existed five phases in the as-cast alloy: α, β, Al2Y, AlLi and MgAlLi2. The spheroidized α phase grew gradually and its microstructure and composition became homogeneous when it was treated at 300 °C for 12 h. Meanwhile, the alloy has a good comprehensive mechanical property compared with other homogenization schedules. So, a homogenization treatment at 300 °C for 12 h was determined to be the optimal homogenization treatment for Mg–8Li–3Al–Y alloy.

Effect of Homogenization Treatment on Microstructure and Properties of ZnAl15 Alloy

The microstructure, microhardness and corrosion resistance of as-cast and as-annealed ZnAl15 alloys were investigated by OM, SEM, EDX and DSC techniques. It was found that microstructure of as-cast ZnAl15 alloy was primary dendrites and eutectic matrix. But Primary discontinuous precipitation of αs and βs phase occurred at room temperature. During homogenization treatment, discontinuous precipitation of αs and βs phase occurred completely and accompanied with emitting heat. The final microstructures of decomposed αs and βs phase in primary dendrites were fine and coarse lamellar structures respectively. The final microstructures of decomposed βs, which located at the edges of the αs phases or in eutectic matrix were that α phase distributed in η matrix. The microhardness of both primary dendrites and eutectic matrix in ZnAl15 alloys decreased after homogenization treatment due to the decomposition of supersaturated solid solutions. The result of accelerated corrosion test showed that homogenization treatment has a certain beneficial effect on the corrosion resistance of ZnAl15 alloy.

Effect of Homogenization Treatment on the Microstructure and Mechanical Property Evolutions of As-Cast Al–Cu Alloy during High-Pressure Torsion

As-cast and homogenization treated as-cast Al­Cu (3mass% Cu) alloy samples were processed via high-pressure torsion (HPT) under an applied pressure of 8GPa with 5 revolutions at room temperature. Microstructure, mechanical properties, and fracture surface morphology of the HPT-processed Al­Cu were investigated, demonstrating that the HPT process successfully resulted in distinct grain refinements in both samples. Significant improvements in the microhardness, tensile properties, and deformation homogeneity due to fine grains, high grain boundary misorientation angle, and homogeneous distribution of the a phase were achieved after the HPT process of the homogenized sample. The homogenization treatment of the as-cast Al­Cu has a significant effect on the fracture surface morphology and fracture mode of the HPTprocessed samples. [doi:10.2320/matertrans.M2014047]

Effect of homogenization treatment on microstructure evolution and the distributions of RE and Zr elements in various Mg–Li–RE–Zr alloys

Mg–3Li–0.4Zr alloys containing RE elements (Gd, La, Nd) (Mg–3Li–RE–0.4Zr alloys) are investigated to reveal the influence of homogenization treatment on microstructures and distributions of RE, Zr elements. It is found that 300 °C × 24 h homogenization treatment shows better improvement on the microstructure including the refinement of grain size, the dispersion of cellular dendrite and low melting point particles. Before treatment, La and Nd segregate effectively at grain boundary and Zr segregates in the form of precipitates. Homogenization treatment induces the reduction of RE segregation. However, the segregation of Zr in precipitates cannot be abated due to the relatively low diffusion rate compared with RE elements.

Multiple hypotheses testing procedures in clinical trials and genomic studies.

We review and compare multiple hypothesis testing procedures used in clinical trials and those in genomic studies. Clinical trials often employ global tests, which draw an overall conclusion for all the hypotheses, such as SUM test, Two-Step test, Approximate Likelihood Ratio test (ALRT), Intersection-Union Test (IUT), and MAX test. The SUM and Two-Step tests are most powerful under homogeneous treatment effects, while the ALRT and MAX test are robust in cases with non-homogeneous treatment effects. Furthermore, the ALRT is robust to unequal sample sizes in testing different hypotheses. In genomic studies, stepwise procedures are used to draw marker-specific conclusions and control family wise error rate (FWER) or false discovery rate (FDR). FDR refers to the percent of false positives among all significant results and is preferred over FWER in screening high-dimensional genomic markers due to its interpretability. In cases where correlations between test statistics cannot be ignored, Westfall-Young resampling method generates the joint distribution of P-values under the null and maintains their correlation structure. Finally, the GWAS data from a clinical trial searching for SNPs associated with nephropathy among Type 1 diabetic patients are used to illustrate various procedures.

Applying optimal model selection in principal stratification for causal inference

Noncompliance to treatment allocation is a key source of complication for causal inference. Efficacy estimation is likely to be compounded by the presence of noncompliance in both treatment arms of clinical trials where the intention-to-treat estimate provides a biased estimator for the true causal estimate even under homogeneous treatment effects assumption. Principal stratification method has been developed to address such posttreatment complications. The present work extends a principal stratification method that adjusts for noncompliance in two-treatment arms trials by developing model selection for covariates predicting compliance to treatment in each arm. We apply the method to analyse data from the Esprit study, which was conducted to ascertain whether unopposed oestrogen (hormone replacement therapy) reduced the risk of further cardiac events in postmenopausal women who survive a first myocardial infarction. We adjust for noncompliance in both treatment arms under a Bayesian framework to produce causal risk ratio estimates for each principal stratum. For mild values of a sensitivity parameter and using separate predictors of compliance in each arm, principal stratification results suggested that compliance with hormone replacement therapy only would reduce the risk for death and myocardial reinfarction by about 47% and 25%, respectively, whereas compliance with either treatment would reduce the risk for death by 13% and reinfarction by 60% among the most compliant. However, the results were sensitive to the user-defined sensitivity parameter.

The effect of homogenization treatment on microstructure and properties of ZnAl15 solder

The effect of homogenization treatment before extrusion process on microstructure and properties of ZnAl15 solders was investigated. The results of observing microstructure shown that homogenization treatment increased the structural homogeneity and stability of ZnAl15 solder. The results of microhardness measurements and reverse bend test indicated that the homogenized ZnAl15 solder resulted in lower microhardness and much higher ductility. Corrosion behavior of non-homogenized and homogenized ZnAl15 solders was studied in 3.5wt.% NaCl solution using immersion test and Tafel plots and resulted in higher corrosion resistance of the homogenized ZnAl15 solder.

Overall survival (OS) benefit with sipuleucel-T by baseline PSA: An exploratory analysis from the phase III IMPACT trial.

4648 Background: Sipuleucel-T is an autologous cellular immunotherapy approved for asymptomatic or minimally symptomatic metastatic castrate-resistant prostate cancer. In the IMPACT trial, sipuleucel-T showed a 22.5% reduction in risk of death vs the control group (hazard ratio [HR]=0.775 [95% CI 0.614, 0.979]; P=0.032). A pre-specified subgroup analysis for baseline prognostic variables showed homogeneous treatment effects consistently favoring sipuleucel-T. In patients (pts) with baseline PSA below vs above the median, there was a trend toward greater treatment effect (HR=0.685 vs. 0.865). In this exploratory analysis, we further sub-divide baseline PSA into quartiles to evaluate potential treatment effect patterns. Methods: The analysis included all randomized pts from IMPACT (n=512). Pts were categorized by baseline PSA quartile (Table), ECOG PS and by median for other baseline prognostic variables (i.e., LDH, PAP, ALP in bone-only disease, and Hgb). Median OS and HR were estimated using Kaplan-Meier and Cox models, respectively. Results: Increasing baseline PSA quartile was associated with markers of advanced disease. HRs suggest a consistent treatment effect in all subsets, although there is inadequate power to show significant results within each quartile. There was a trend toward an increased magnitude of treatment benefit in pts with a lower baseline PSA (Table). Results for other baseline prognostic variables also suggest a trend toward greater benefit in subjects with better prognostic features. However, results for baseline Hgb indicated an opposite trend. Conclusions: Although not adequately powered for significance, the results of this analysis support a consistent OS benefit with sipuleucel-T across PSA quartiles. The greater magnitude of benefit in pts with lower baseline PSA suggests that pts with less advanced disease may benefit more from treatment with sipuleucel-T. [Table: see text]

WAGES AND WORKPLACE COMPUTER USE IN CHILE

This paper presents robust evidence regarding the impact of computer use in the workplace in Chile during the period 2000–2006. The key contribution of this paper is to present evidence for a developing country using matching techniques and assuming a homogeneous treatment effect. Wage impact is then measured through the nearest neighbor and kernel estimators. The results consistently show that there is a premium associated with the use of computers in the workplace, interpreted as an increase in worker productivity arising from the inclusion of an additional production factor (i.e., the computer). Estimates indicate a premium of around 26% for 2000 and 16% for 2006.

Effects of Homogenization Treatment on Microstructure and Properties of Mg-Zn-Nd-Cd-Zr Alloy

Mcrostructure and properties of Mg-Zn-Nd-Cd-Zr alloy have been investigated on different solution treatments and artificial aging conditions by optical microscope, SEM (scanning electron microscope) and TEM(transmission electron microscope). The results indicate that the grain boundarys become thinner and the second phases distributed on the grain boundarys become finer by double-stage homogenization at 400°C for 2h plus 460°C for 12h than that of homogenization at 420°C for 24h. Double-stage homogenization brings a greater peak-ageing hardness and longer time to reach peak hardness 20h about., and the ultimate tensile strength is 345MPa at 140°C for 34h, higher 15% than that of as-extruded

Effect of homogenization treatment on microstructure and properties for Cu–Fe–Ag in situ composites

Abstract The effects of homogenization treatment on the microstructure and properties of Cu–8Fe–0.1Ag and Cu–8Fe–0.5Ag (wt.%, similarly hereinafter) in situ composites were investigated. The composites were prepared by inductive melting, casting, homogenization treatment and subsequent cold work. Microstructures of the composites were observed and the tensile strength plus electrical conductivity was measured respectively. The results show that the prior homogenization treatment results in refinement of the primary Fe dendrites in Cu matrix and promotes the precipitation of the secondary Fe particles from the Cu matrix, which leads to increase in the strength and conductivity of the composites. During the following cold deformation, the homogenized alloys are readily elongated into fine and continuous filamentary composites compared with the as-cast, leading to high strength due to the increased interface density.

Physicochemical properties of chitosan-essential oils filmforming dispersions. Effect of homogenization treatments

Chitosan films enriched with basil (B) or thyme (T) essential oils (EO) were prepared by means of two homogenization treatments, without (H1) and with (H2) microfluidization. H2 treatment led to a significant decrease in the average particle size and the type of EO significantly affected d43 values (p<0.05). ς-potential significantly increased with the use of H2 treatment. Treatment H2 changed the rheological behaviour of the FFD. In all cases, the viscosity of the FFD was reduced by this treatment. The type of EO had a different effect on rheological behaviour depending on the homogenization treatment. CH:T were more viscous at H2 and CH:A showed higher apparent viscosity values than CH:T at H1.

Regional differences in multinational clinical trials: anticipating chance variation

Multinational clinical trials efficiently pool resources and provide treatment comparisons across diverse populations. However, they may be difficult to interpret when there are larger than expected differences in region-specific treatment effects, such as a positive study that includes regions favoring the control arm. This article investigates the extent of chance variation that can be expected in regional treatment effects from multinational studies. It advocates studying this expected variation during the design stage, hence limiting the potential for surprises and misinterpretations at the end of the study. The theory of order statistics was used to quantify chance variation between regions, assuming a homogeneous treatment effect. The expected values of the smallest and largest treatment difference were used to calculate the expected range of regional effects. This range was supplemented by the probability of observing at least one regional effect favoring the control arm. Chance variation led to a wide range of expected regional effects. For a study with five regions and 80% power, the expected regional treatment effects ranged from no difference to double the true difference, while the probability of observing a region favoring the control was approximately 50%. With 10 regions this probability exceeded 85% and the expected range of regional effects extended to values substantially favoring the control. Increasing the power of the study to 90% or more offered little protection against wide variation in regional effects. The proposed approach does not replace heterogeneity testing at the end of the study, but provides useful supporting information for interpreting such tests. Large differences between regions should be anticipated in multinational studies. The expected range of treatment effects should be assessed during study design in order to inform stakeholders and calibrate expectations.