Sequential comparison of two treatments in clinical trials:a decision theoretic approach based on randomized play-the-winner rule

In the context of comparing two treatments in clinical trials randomized play-the-winner rule is used with the goal of treating more patients by the better treatment On its basis we give two decision rules by introducing stopping rule Some performance characteristics of one of the decision rules are discussed and examined .A minimax rule is suggested Finally some exact and asymptotic properties of the decision rule is derived     

An alternative one sided test of normal mean

This paper provides an alternative test procedure for the problem oftesting of normal mean for one sided alternative when the variance is known in case of costly trials. The proposed test is based on a sampling scheme which we call 'continuous adaptive design'. Some exact andasymptotic results related to the test and design are studied.     

Spinodal clustering induced dewetting and non-monotonic stabilization of polymer blend films at high nanofiller concentrations

We examine the effects of high fullerene nanoparticle (f-NP) concentrations, ?_f-NP ∼ (10–20) mass% on polystyrene (PS)/polybutadiene (PB) blend thin film stability. Dewetting of the polymer blend around spinodally clustered f-NPs in this high concentration limit leads to a spinodal like dewetting morphology. This is in contrast to our previously observed results on the stabilization effects of f-NPs on PS/PB blend thin films in the intermediate f-NP concentration range of 7–10 mass%, wherein, after saturating the polymer–blend interface, the NPs stabilize the film by segregating to the blend–substrate interface. We determine three regimes of polymer blend film stability as a function of filler concentration: a) ?_f-NP < 7 mass% where preferential segregation of the f-NPs to the polymer–polymer interface leads to macroscopic dewetting, b) ?_f-NP ∼ (7–10) mass% where PS/PB blend films exhibit complete film stability, and c) ?_f-NP ∼ (11–20) mass%, where spinodal clustering of the f-NPs gives rise to polymer–NP phase exclusion and subsequent dewetting.     

Absorption of carbon dioxide in alkanolamines in the presence of fine activated carbon particles

The rates of absorption of CO₂ into water and 0.1 kmol/m³ aqueous solutions of MEA, DEA and AMP were measured in a stirred cell with a flat gas-liquid interface in the presence of fine activated carbon particles. Experiments showed that the rates of absorption increased significantly with increases in the loading of activated carbon up to about 6 kg/m³ and thereafter remained constant.     

Studies on sulfur vulcanization of natural rubber accelerated combinedly with 2-mercaptobenzothiazole and diphenylguanidine both in presence and absence of dicumyl peroxide

Sulfuration of natural rubber (NR) by the binary accelerator 2-mercaptobenzothiazole (MBT) and diphenylguanidine (DPG) both in presence and in absence of ZnO and stearic acid with or without dicumylperoxide (DCP) was studied in detail. It was observed that the rate of decomposition of DCP in presence of both MBT and DPG is quite similar to that with MBT alone. The reduction of crosslinking depends also on MBT only. Through DPG has no influence on the decomposition rate, it reacts with MBT during the vulcanization process and suppresses the retardation caused by MBT on the DCP vulcanization. In accordance with the initial additiveness of crosslinking in systems containing DCP, the free sulfur decrease, and the rapidity of crosslink formation the vulcanization process of MBT-DPG-S-NR systems was interpreted in terms of a polar mechanism induced by the complex MSH₂NR′R″. In mixtures containing DCP together with sulfur, MBT, DPG, ZnO, and stearic acid, the initial stage of crosslinking is additive as indicated by a mixed reaction as well as by a methyl iodide treatment of the vulcanizates. Comparison with single accelerators shows a pronounced synergistic effect. This is because of the enhanced activity of the MBT-ZnO-stearic acid complex due to DPG which also induces polar sulfuration of NR by forming the active complex MSH₂NR′R″. In presence of ZnO and stearic acid, DCP cannot increase the net crosslink density but suppresses the reversion so much pronounced in its absence.     

Synthesis of AlPO4 Molecular Sieves with AFI and AEL Structures by Dry-Gel Conversion Method and Catalytic Application of Their SAPO Counterparts on Isopropylation of Biphenyl

AlPO₄-5 and AlPO₄-11 were synthesized by dry-gel conversion (DGC) method. Steam-assisted conversion (SAC) and vapor-phase transport (VPT) techniques were applied for this purpose. The synthesis was successful in presence of a certain minimum amount of external bulk water, without which the crystallization failed. Crystallization by VPT method was slower than corresponding SAC and HTS method. SAPO analogs of the samples, SAPO-5 and SAPO-11 were also synthesized by DGC method. Samples made by DGC methods had higher yield than the conventional hydrothermal synthesis (HTS); otherwise the samples showed similar characteristics as that made by HTS. XRD, SEM and N₂-adsorption results showed high crystallinity and purity of the samples made by DGC, and ²⁷Al MAS NMR spectra indicated the tetrahedral framework nature of Al. SAPO-5 and SAPO-11 were tested for their catalytic activity in isopropylation of biphenyl, and in terms of conversion and selectivity, SAPO-5 was found to be suitable for this application.     

Improvement of polymer blend properties by changing sequence of mixing

The basic objective of this article is to improve the polymer blend properties by changing mixing sequence. Blending of two elastomers does not lead to a molecularly homogeneous blend (true solution), but to a heterogeneous system in which both polymer phases are present. In this article, the detailed study of heterogeneous distribution of carbon black as well as blend inhomogenity and the physicomechanical including dynamic mechanical properties of the blend has been carried out. The choice of the blend was natural rubber/polybutadiene rubber as 85:15. Heterogeneous carbon black distribution study was also performed in differential scanning calorimeter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2735–2742, 2007     

Simulation of single phase non-Newtonian flow characteristics of heavy crude oil through horizontal pipelines

The effect of diameter, velocity, and temperature on flow properties of heavy crude oil in three horizontal pipelines using computational fluid dynamics (CFD) was studied. The flow characteristics were simulated by using CFD software, ANSYS Fluent 6.2. The mesh geometry of the pipelines having inner diameter of 1, 1.5, and 2 inch were created by using Gambit 2.4.6. From grid independent study, 221, 365 mesh sizes were selected for simulation. The CFD ANSYS Fluent 6.2 Solver predicted the flow phenomena, pressure, pressure drop, wall shear stress, shear strain rate, and friction factor. A good agreement between experimental and CFD simulated values was obtained.     

Contribution of resonance to ground bounce in lossy thin filmplanes

This paper discusses the pulse propagation effects on lossy thin film planes. The ground bounce phenomena produced by the resonance on planes has been captured using a combination of modeling techniques and measurements. Macromodeling method has been used to explain the transient phenomena on planes by using the dominant poles and residues of the system