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This work was supported by Edith Cowan University (ECU), Australia, Early Career Research Grant No. G1003450. The authors would like to thank ECU, Australia, for the Ph.D. grant vide ECU HDR Scholarship-2018.

Today, bi - reforming of methane is considered as an emerging replacement for the generation of high-grade synthesis gas (H2:CO = 2.0), and also as an encouraging renewable energy substitute for fossil fuel resources. For achieving high conversion levels of CH4, H2O, and CO2 in this process, appropriate operation variables such as pressure, temperature and molar feed constitution are prerequisites for the high yield of synthesis gas. One of the biggest stumbling blocks for the methane reforming reaction is the sudden deactivation of catalysts, which is attributed to the sintering and coke formation on active sites. Consequently, it is worthwhile to choose promising catalysts that demonstrate excellent stability, high activity and selectivity during the production of syngas. This review describes the characterisation and synthesis of various catalysts used in the bi-reforming process, such as Ni-based catalysts with MgO, MgO–Al2O3, ZrO2, CeO2, SiO2 as catalytic supports. In summary, the addition of a Ni/SBA-15 catalyst showed greater catalytic reactivity than nickel celites; however, both samples deactivated strongly on stream. Ce-promoted catalysts were more found to more favourable than Ni/MgAl2O4 catalyst alone in the bi-reforming reaction due to their inherent capability of removing amorphous coke from the catalyst surface. Also, Lanthanum promoted catalysts exhibited greater nickel dispersion than Ni/MgAl2O4 catalyst due to enhanced interaction between the metal and support. Furthermore, La2O3 addition was found to improve the selectivity, activity, sintering and coking resistance of Ni implanted within SiO2. Non-noble metal-based carbide catalysts were considered to be active and stable catalysts for bi-reforming reactions. Interestingly, a five-fold increase in the coking resistance of the nickel catalyst with Al2O3 support was observed with incorporation of Cr, La2O3 and Ba for a continuous reaction time of 140 h. Bi-reforming for 200 h with Ni-γAl2O3 catalyst promoted 98.3% conversion of CH4 and CO2 conversion of around 82.4%. Addition of MgO to the Ni catalyst formed stable MgAl2O4 spinel phase at high temperatures and was quite effective in preventing coke formation due to enhancement in the basicity on the surface of catalyst. Additionally, the distribution of perovskite oxides over 20 wt % silicon carbide-modified with aluminium oxide supports promoted catalytic activity. NdCOO3 catalysts were found to be promising candidates for longer bi-reforming operations.

The energy industry is exploring sustainable chemistry and engineering solutions for exploitation of shale reservoirs. Smectite-rich shale is challenging to drill with traditional water-based drill...

The Mancos shale core sample investigated in the present research has been extracted from the late Cretaceous (upper cretaceous) geologic formation of USA. Shale gas is usually obtained by horizont...

Unconventional shale gas reservoir requires fracture network for exploitation from nano-Darcy shale where reservoirs have a space-to-space variation. This study is aimed to investigate the potential of Mancos Shale formation for the purpose of hydrocarbon recovery using numerical analysis of cryogenic liquid treatment. In this study, at first, the core samples of Mancos Shale from the Late Cretaceous (upper Cretaceous) geologic development were treated before and after cryogenic liquid nitrogen for different treatment times specifically 30, 60, and 90 min, respectively. Later, the numerical simulation is used to determine the overall gas production under different confining stress scenarios with different treatment times. In this study, the candidate reservoir is simulated on a simple layer cake model having a thickness 450 ft to simulate production scenarios for different ranges of permeability and porosity. The simulation results for the Mancos shale gas reservoir are obtained with net confining stress ranging from 1000 to 7000 psi. The simulation reveals that the recovery obtained before fracture treatment was 0.0004 SCTR with quite a low production. Nevertheless, an increase in the exposure time of cryogenic treatment through the liquid nitrogen LN2 process enhanced the gas recovery to a maximum level of 2.2 SCTR at confining stress of 7000 psi. Hence, simulation studies have shown that cryogenic liquid nitrogen treatment has a profound effect to increase the production of shale gas.

During the hydrometallurgical processing of nickel from raw materials, the leach liquors are found to be contaminated with several impurities. These impurities in the electrolytic cell affect the deposition characteristics as well as the kinetics and mechanism of nickel electrodeposition process resulting in lower current efficiency (CE) and poor nickel deposits. In order to improve the quality of the nickel deposits, it is imperative to use organic additives in the nickel plating bath to improve the structural, mechanical, and morphological properties of the deposits. Furthermore, it is usually observed that in spite of various purification techniques like cementation and solvent extraction, metals obtained at the cathode are usually contaminated with inorganic impurities. This review thus presents a comprehensive overview of some important studies and investigations performed on various inorganic and organic additives employed in nickel electrodeposition processes from various baths such as Watts, sulfate, acetate, formamide, lactate, and baths containing ionic liquids. The presence of metallic (inorganic) impurities in industrial electrolytes is very common. Most of these impurities affect the deposit’s characteristics, CE, deposition overvoltage, and cathode purity. Addition of inorganic cations such as Al3+, Mg2+, Mn2+, and Zn2+ did not have a significant effect on the CE; nevertheless, the physical appearance and crystallographic orientation of nickel deposits were significantly affected. Organic additives are usually added to the nickel electrolytic bath to counter the harmful effects of these metallic impurities entrained in the bath, where they also affect the growth and crystal building of the deposits through their adsorption onto the cathode surface. Most of these additives act as hydrogen inhibitors, crystal growth modifiers, brighteners, levelers, wetting agents, and stress reducers, and hence, their appropriate addition was important for the formation of fine-grained, smooth, and compact deposits. This review demonstrates that the quality of the nickel deposit was strongly affected if the concentration of the inorganic impurity in the nickel bath exceeded the tolerance limit. From this review article, the roles of various organic additives as a brightener, leveler, and antipitting agent, etc. in the Ni plating bath could be established, and these additives would play a significant role in the formation of bright, smooth, and coherent nickel deposits obtained during hydrometallurgical processing of laterite and sulfide ores in the metallurgical industry.

Eagle Ford shale formations have great hydrocarbon potential to minimise the supply and demand problems of the overgrowing population. Whereas, due to reduced permeability and marginal porosity, it is very difficult to produce from these formations. Previously, hydraulic fracturing and acidizing techniques are used to produce the hydrocarbons from tight gas shale formations; however, due to technical difficulties and environmental problems have led to a ban on these techniques in many countries. Therefore, it is suggested to use water-less fracturing methods to avoid these problems. Recently, liquid nitrogen (LN2) cooling have shown a great potential to mitigate technical and environmental flaws, which works on the principle of providing sudden thermal shocks in the pore matrix, thus inducing micro-cracks and enhancing the petro-physical potential. In this study, we have collected tight gas shale samples from the Eagle Ford shale's Upper Late Cretaceous geologic formation in the United States. Initially, these samples were exposed to LN2 for various time intervals of 30, 60, and 90 min and were characterised based on their petro-physical, morphology, topography, and rock mechanical properties before and after LN2 exposure. To accomplish that, various techniques were used such as core flooding, porosity determination, microstructural characterisation via field emission scanning electron spectroscopy (FESEM) and energy dispersive spectroscopy (EDS), topographic characterisation via atomic force microscopy (AFM), and rock mechanical characterisation via nano-indentation technique. It is evident from our results that LN2 cooling has a substantive effect on petro-physical properties by increasing permeability from 12 nano-Darcy (nD) to 2.6 milli-Darcy (mD) and porosity from 2.32% to 4.46%. Similarly, topographic properties have shown an increase in surface roughness from 177 nm to 692 nm, and hardness (indentation moduli, GPa) was substantially reduced due to optimum exposure of LN2 at 90 min. Further, thermal shocks of LN2 cooling have induced vivid micro-cracks in the pore matrix up to 7 μm. In a nutshell, it is vital to augment the effects of LN2 cooling on microstructural, petro-physical, topography, and rock mechanical properties for better understanding in the development of hydrocarbon potential in Eagle Ford shale formations.

Significant amounts of hydrocarbons are contained in tight carbonate rocks like those within the Indus basin of Pakistan, but due to their unconventional nature, their extraction is difficult. This can be completed/conducted by properly characterizing its mineralogical, geochemical and microstructural properties. In this context, Hydraulic fracturing and acidizing are the most common fracture stimulation techniques. However, they suffer significant technical and environmental flaws. Liquid Nitrogen (LN2) fracking is considered as one of the best alternatives compare to hydraulic fracturing or acidizing due to its eco-friendly nature. In fact, after exposer to LN2, super cryogenic feature of the rock causes porosity, permeability and fracture conductivity enhancement due to thermal shock without any environmental consequences. The effect of Liquid Nitrogen fracking on tight carbonate outcrops collected from the Indus basin is investigated in the present study. Scanning Electron Microscopy (SEM) reveals the clear appearance of wide pore fractures with sizes from 4 μm to 50 μm, when subjected to liquid Nitrogen (LN2) treatment ranging from 30 to 90 min’ duration. Furthermore, SEM and Atomic Force Microscopy (AFM) images also indicate clear pore fractures in tight carbonate rocks along with increased pore connectivity. Moreover, following liquid nitrogen treatment of up to 90 min the permeability of tight carbonate increases by 53% and increases in porosity by 73%. Results from SEM studies suggest that visible fractures occur in the tight carbonate samples with liquid nitrogen treatment because of the freezing temperature (−196 ⸰C) of Liquid Nitrogen. In addition to this, Nano indentation moduli depict significant decreases in tight carbonate rocks, both before and after exposure to LN2, as a result of increases in liquid rock compressibility. In this regard, a 50 mN force decreased from 50.57 GPa to 24.37 GPa and for a 200 mN force this decreased from 45.77 GPa to 26.67 GPa. This research depicts the significant effect of Liquid Nitrogen freezing on the fracturing of carbonate rocks.

Pyrometallurgical metal production results in side streams, such as dusts and slags, which are carriers of metals, though commonly containing lower metal concentrations compared to the main process stream. In order to improve the circular economy of metals, selective leaching of copper from an intermediate raw material originating from primary base metal production plant was investigated. The raw material investigated was rich in Cu (12.5%), Ni (2.6%), Zn (1.6%), and Fe (23.6%) with the particle size D80 of 124 µm. The main compounds present were nickel ferrite (NiFe2O4), fayalite (Fe2SiO4), cuprite (Cu2O), and metallic copper. Leaching was studied in 16 different solutions. The results revealed that copper phases could be dissolved with high yield (>90%) and selectivity towards nickel (Cu/Ni > 7) already at room temperature with the following solutions: 0.5 M HCl, 1.5 M HCl, 4 M NaOH, and 2 M HNO3. A concentration of 4 M NaOH provided a superior selectivity between Cu/Ni (340) and Cu/Zn (51). In addition, 1-2 M HNO3 and 0.5 M HCl solutions were shown to result in high Pb dissolution (>98%). Consequently, 0.5 M HCl leaching is suggested to provide a low temperature, low chemical consumption method for selective copper removal from the investigated side stream, resulting in PLS (pregnant leach solution) which is a rich in Cu and lead free residue, also rich in Ni and Fe.

Pocock et al. (2012, European Heart Journal 33, 176-182) proposed a win ratio approach to analyzing composite endpoints comprised of outcomes with different clinical priorities. In this article, we establish a statistical framework for this approach. We derive the null hypothesis and propose a closed-form variance estimator for the win ratio statistic in all pairwise matching situation. Our simulation study shows that the proposed variance estimator performs well regardless of the magnitude of treatment effect size and the type of the joint distribution of the outcomes.

Potentiodynamic polarization techniques were employed in the present study to investigate the corrosion behavior of Pb-free Sn-1Ag-0.5Cu-XNi solder alloys in 3.5% NaCl solution. Polarization studies indicated that an increase in Ni content from 0.05 wt.% to 1 wt.% in the solder alloy shifted the corrosion potential (Ecorr) towards more negative values and increased the linear polarization resistance. Increased addition of Ni to 1 wt.% resulted in significant increase in the concentration of both Sn and Ni oxides on the outer surface. Secondary-ion mass spectrometry and Auger depth profile analysis revealed that oxides of tin contributed primarily towards the formation of the passive film on the surface of the solder alloys containing 0.05 wt.% and 1 wt.% Ni. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) established the formation of a Sn whisker near the passive region of the solder alloy obtained from the polarization curves. The formation of Sn whiskers was due to the buildup of compressive stress generated by the increase in the volume of the oxides of Sn and Ni formed on the outer surface. The presence of Cl− was responsible for the breakdown of the passive film, and significant pitting corrosion in the form of distinct pits was noticed in Sn-1Ag-0.5Cu-0.5Ni solder alloy after the polarization experiment.

Objectives The purpose of this study was to understand the possible risk of discontinuation in the context of clinical care. Background Rivaroxaban is noninferior to warfarin for preventing stroke in atrial fibrillation patients. Concerns exist regarding possible increased risk of stroke and non–central nervous system (CNS) thromboembolic events early after discontinuation of rivaroxaban. Methods We undertook a post-hoc analysis of data from the ROCKET AF (Rivaroxaban Once-Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation, n = 14,624) for stroke or non-CNS embolism within 30 days after temporary interruptions of 3 days or more, early permanent study drug discontinuation, and end-of-study transition to open-label therapy. Results Stroke and non-CNS embolism occurred at similar rates after temporary interruptions (rivaroxaban: n = 9, warfarin: n = 8, 6.20 vs. 5.05/100 patient-years, hazard ratio [HR]: 1.28, 95% confidence interval [CI]: 0.49 to 3.31, p = 0.62) and after early permanent discontinuation (rivaroxaban: n = 42, warfarin: n = 36, 25.60 vs. 23.28/100 patient-years, HR: 1.10, 95% CI: 0.71 to 1.72, p = 0.66). Patients transitioning to open-label therapy at the end of the study had more strokes with rivaroxaban (n = 22) versus warfarin (n = 6, 6.42 vs. 1.73/100 patient-years, HR: 3.72, 95% CI: 1.51 to 9.16, p = 0.0044) and took longer to reach a therapeutic international normalized ratio with rivaroxaban versus warfarin. All thrombotic events within 30 days of any study drug cessation (including stroke, non-CNS embolism, myocardial infarction, and vascular death) were similar between groups (HR: 1.02, 95% CI: 0.83 to 1.26, p = 0.85). Conclusions In atrial fibrillation patients who temporarily or permanently discontinued anticoagulation, the risk of stroke or non-CNS embolism was similar with rivaroxaban or warfarin. An increased risk of stroke and non-CNS embolism was observed in rivaroxaban-treated patients compared with warfarin-treated patients after the end of the study, underscoring the importance of therapeutic anticoagulation coverage during such a transition.

The effect of Ag on the microstructure and thermal behavior of Sn-Zn and Sn-8.5Zn-xAg-0.01Al-0.1Ga solders (x from 0.1 wt.% to 1 wt.%) under high-temperature/relative humidity conditions (85°C/85% RH) for various exposure times was investigated. Scanning electron microscopy (SEM) studies revealed that, in all the investigated solders, the primary α-Zn phases were surrounded by eutectic β-Sn/α-Zn phases, in which fine Zn platelets were dispersed in the β-Sn matrix. SEM micrographs revealed that increase of the Ag content to 1 wt.% resulted in coarsening of the dendritic plates and diminished the Sn-9Zn eutectic phase in the microstructure. Differential scanning calorimetry (DSC) studies revealed that the melting temperature of Sn-8.5Zn-xAg-0.01Al-0.1Ga solder decreased from 199.6°C to 199.2°C with increase of the Ag content in the solder alloy. Both ZnO and SnO2 along with Ag-Zn intermetallic compound (IMC) were formed on the surface when Sn-8.5Zn-0.5Ag-0.01Al-0.1Ga solder was exposed to high-temperature/high-humidity conditions (85°C/85% RH) for 100 h. The thickness of the ZnO phase increased as the Ag content and exposure time were increased. Sn whiskers of various shapes and lengths varying from 2 μm to 5 μm were extruded from the surface when the investigated five-element solder with Ag content varying from 0.5 wt.% to 1 wt.% was exposed to similar temperature/humidity conditions for 250 h. The length and density of the whiskers increased with further increase of the exposure time to 500 h and the Ag content in the solder to 1 wt.%. The Sn whisker growth was driven by the compressive stress in the solder, which was generated due to the volume expansion caused by ZnO and Ag-Zn intermetallic compound formation at the grain boundaries of Sn.

Background: The potential impact of missing data on the results of clinical trials has received heightened attention recently. A National Research Council study provides recommendations for limiting missing data in clinical trial design and conduct, and principles for analysis, including the need for sensitivity analyses to assess robustness of findings to alternative assumptions about the missing data. A Food and Drug Administration advisory committee raised missing data as a serious concern in their review of results from the ATLAS ACS 2 TIMI 51 study, a large clinical trial that assessed rivaroxaban for its ability to reduce the risk of cardiovascular death, myocardial infarction or stroke in patients with acute coronary syndrome. This case study describes a variety of measures that were taken to address concerns about the missing data. Methods: A range of analyses are described to assess the potential impact of missing data on conclusions. In particular, measures of the amount of missing data are discussed, and the fraction of missing information from multiple imputation is proposed as an alternative measure. The sensitivity analysis in the National Research Council study is modified in the context of survival analysis where some individuals are lost to follow-up. The impact of deviations from ignorable censoring is assessed by differentially increasing the hazard of the primary outcome in the treatment groups and multiply imputing events between dropout and the end of the study. Tipping-point analyses are described, where the deviation from ignorable censoring that results in a reversal of significance of the treatment effect is determined. A study to determine the vital status of participants lost to follow-up was also conducted, and the results of including this additional information are assessed. Results: Sensitivity analyses suggest that findings of the ATLAS ACS 2 TIMI 51 study are robust to missing data; this robustness is reinforced by the follow-up study, since inclusion of data from this study had little impact on the study conclusions. Conclusion: Missing data are a serious problem in clinical trials. The methods presented here, namely, the sensitivity analyses, the follow-up study to determine survival of missing cases, and the proposed measurement of missing data via the fraction of missing information, have potential application in other studies involving survival analysis where missing data are a concern.

The nanoparticles of tin-silver solder, Sn-3.5Ag, of necklace geometry were made in a swirl batch. It was found that the addition of the element, Ag, did not vary the microstructure of the solder matrix, but Ag simply diluted into the Sn matrix randomly. The swirl flow facilitated the formation of particles with different sizes. It was found that the size distribution of the nanoparticles was strongly related to the height in the swirl batch. In addition, the aggregation of the nanoparticles was explored and the dispersion of the nanoparticles was achieved by adjusting the pH value of the solution near the neutral value.

The synthesis of Sn-3.5Ag alloy nanosolder was investigated by chemical reduction method. In this method, chemical precipitation was achieved by using sodium NaBH4 as a reducing agent and PVP (poly-m-vinyl 2- pyrrolidone) as a stabilizer. The experimental results obtained with different amounts of NaBH4 and PVP were compared. X-ray diffraction (XRD) patterns revealed that Ag3Sn was formed due to the successful alloying process. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) demonstrated a change in the morphology of Sn-3.5 Ag alloy nanosolder with increase in the PVP content in the bath. The size of the nanoparticles ranged from 300 to 700 nm. The nanosolder/nanoparticles were thus synthesized successfully under controlled and optimized chemical reduction process.

The synthesis of various nanoscale materials, such as nanoparticles, nanowires of Au, Pt, Ni Co, Fe, Ag etc., by electrodeposition techniques have been demonstrated in this article. Both potentiostatic and galvanostatic methods were employed to carry out the electrodeposition process under different potential ranges, time durations, and current densities. The electrochemical behavior of the deposited nanoparticles on various substrates was investigated by cyclic voltammetric and chronoamperometric techniques. The synthesis of mono-dispersed gold (Au) nanoparticles on indium tin oxide (ITO) coated glass, preparation of Au nanorods on nanoporous anodic alumina oxide (AAO), formation of Au nanoclusters on polypyrrole-modified glassy carbon electrode and one-step electrodeposition of nickel nanoparticle chains embedded in TiO2 etc. have been highlighted in this article. The potential applications of synthesized nanoparticles such as the role of maghemite (Fe2O3) in arsenic remediation, higher electrocatalytic activity of Ag nanoclusters for the reduction of benzyl chloride, and the role of C60 nanoparticle-doped carbon film in fabrication processes are also presented in this article.

Summary Purpose: To identify and validate the efficacious monotherapy dosing regimen for topiramate in children aged 2 to

The effect of sodiumlaurylsulphate (SLS) on the cathodic current efficiency (CE), surface morphology, crystallographic orientations and polarization behaviour of the stainless steel cathode during nickel electrowinning from acidic sulphate solutions was investigated. The results indicated that SLS did not have a significant effect on the cathodic current efficiency. However, noticeable changes in the surface morphology and deposit quality were observed. Cyclic and linear sweep voltammetric studies revealed that an increase in SLS concentration from 2 to 40 mg dm− 3 increased the cathodic potential and shifted the nucleation overpotential (NOP) towards more negative values which was also reflected in the decrease in the rate of electron transfer i.e. i0 values obtained on both the stainless steel and nickel substrates. The presence of SLS did not change the fcc structure of the electrodeposited nickel but affected the peak intensities of the various crystal planes.

An attempt was made to synthesize Sn-3.5Ag-0.5Zn alloy nanoparticles by chemical reduction method. The chemical precipitation was carried out by using NaBH4 as a reducing agent and poly-m-vinyl 2-pyrrolidone (PVP) as a stabilizer. The Zn content was varied from 0.5 to 3.5 wt%. The microstructure of the nanoparticles were determined by using techniques such as X-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), etc. X-ray diffraction patterns revealed that Ag3Sn was formed due to the successful alloying process. Other intermetallic compounds such as Ag4Sn and Ag5Zn8 were also obtained in the XRD patterns. Results on TEM revealed that the isolated particles were spherical in shape and the particle size varied from 2 to 10 nm. The high-resolution transmission electron microscopy (HRTEM) images for Sn-3.5Ag-0.5Zn alloys showed selected area diffraction patterns for Ag3Sn nanoparticles. However, diffraction patterns for compounds like Ag4Sn and Ag5Zn8 could not be obtained due to the strong aggregation of nanoparticles. The morphology of SnAgZn nanoparticles obtained by SEM revealed that the major particle size of SnAgZn nanoparticles were in the range of 60-80 nm.

The nano-scaled Sn-3.5Ag solder was prepared successfully by a supernatant process in the present study. The morphology of the nano-particle was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. It was found from the SEM micrographs that the average diameter of the particle was 137 nm with a standard deviation of ±5 nm. From the TEM studies it was revealed that the particles aggregated into larger particles and the shape of the elongated particles were irregular. The composition of the alloy was also measured by an electron probe microanalyzer (EPMA) and energy dispersive spectroscopy (EDS), qualitatively and quantitatively. The eutectic element, Ag with a weight percentage of 3.5%, was found to be homogenous over all of the particles. Furthermore, the microstructure of the Sn-3.5Ag alloy was identified by X-ray diffraction. It was found that the trace element, Ag was dissolved in the matrix, a tetragonal system, without an intermetallic phase.

The electrochemical corrosion behaviour of Pb-free Sn–8.5Zn–0.05Al–XGa and Sn–3Ag–0.5Cu alloys was investigated in 3.5% NaCl solution by using potentiodynamic polarization techniques. The results obtained from polarization studies revealed that there was a negative shift in the corrosion potential with increase in Ga content from 0.02 to 0.2 wt% in the Sn–8.5Zn–0.05Al–XGa alloy. These changes were also reflected in the corrosion current density ( I corr ) value, corrosion rate and linear polarization resistance (LPR) of the four element alloy. However, for Sn–3Ag–0.5Cu alloy a significant increase in the corrosion rate and corrosion current density was observed as compared to the four element alloys. SIMS depth profile results established that ZnO present on the outer surface of Sn–8.5Zn–0.05Al–0.05Ga alloy played a major role in the formation of the oxide film. Oxides of Sn, Al and Ga contributed a little towards the formation of film on the outer surface of the alloy. On the other hand, Ag 2 O was primarily responsible for the formation of the oxide film on the outer surface of Sn–3Ag–0.5Cu alloy.

The electrochemical corrosion behavior of Sn–XAg–0.5Cu alloys in 3.5% NaCl solution was examined using potentiodynamic polarization techniques. The Ag content in the alloy was varied from 1 to 4 wt%. The polarization curves obtained for the alloys show an active–passive transition followed by a transpassive region. Sn–XAg–0.5Cu alloys with higher Ag content (>2 wt%) show a strong tendency toward passivation. The passivation behavior has been ascribed to the presence of both SnO and SnO2on the anode surface. Increase in Ag content from 1 to 4 wt% results in a decrease in the corrosion-current density (Icorr) and linear polarization resistance (LPR) of the alloy. Nevertheless, the corrosion potential (Ecorr) shifts toward negative values, and a decrease in corrosion rate is observed. The presence of Cl−ion initiates pitting and is responsible for the rupture of the passive layer at a certain breakdown potential. The breakdown potential (EBR) decreases and shifts toward more noble values with increase in Ag content in the alloy. Surface analyses by x-ray photoelectron spectroscopy (XPS) and Auger depth profile studies confirmed the formation of both Sn(II) and Sn(IV) oxides in the passive layer.

The effect of Al on the electrochemical corrosion behaviour of Pb-free Sn–8.5 Zn–0.5 Ag–XAl–0.5 Ga solder in 3.5% NaCl solution was investigated by using potentiodynamic polarization techniques. The X content in the solder varied from 0.1 to 3 wt.%. Polarization studies revealed that an increase in Al content upto 1.5 wt.% decreased the corrosion current density (Icorr), corrosion rate of the solder and shifted the corrosion potential (Ecorr) towards more noble values. However, higher content of Al, i.e. 3 (wt.%) in the five-element solder enhanced the corrosion rate and resulted in a significant increase in the Ecorr towards more negative values. Passivation behaviour was noticed in all the solders having varying Al content, but the passive film formed at 1.5 wt.% Al was most stable due to its low passivation current density (ip) and low critical current density (icc) value in comparison to the other solders. XPS and Auger depth profile results revealed that the passive film consisted of oxides/hydroxides of Al and Zn formed on the surface of the solder with Sn being formed in the subsequent layer. Considerable aluminium segregation occurred towards the surface principally as Al2O3/Al(OH)3 with increase in Al content to 1.5 wt.% in the five element solder. The formation of Al2O3 seemed to prevent the oxidation of zinc on the surface of the solder.

The polarization characteristics of Sn–8.5Zn–0.5Ag–0.1Al– X Ga lead-free solders were investigated in 3.5% NaCl solution where X ranges from 0.05–1.5 wt%. The results show that Ga affects the anodic polarization behaviour of the solders. Passivation behaviour is observed for all the investigated Sn–8.5Zn–0.5Ag–0.1Al– X Ga solders. Increase in the Ga content from 0.05 to 0.25 wt% increases the ability for passivation but the oxide film formed due to passivity is not so protective. However Ga content > 0.25 wt% enhances corrosion and decreases the protective power of the passive film. The magnitude of the passivation current densities depend on the composition of the solders and the potentials applied. Layers of oxides of tin and zinc are responsible for the passivation behaviour. XRD and SEM results revealed the formation of corrosion products like SnO, ZnO, SnO 2 at different potentials during the polarization study.

The effect of thiourea on the cathodic current efficiency (CE), deposit quality, crystallographic orientations, surface morphology, and polarization behavior of the cathode was investigated during nickel electrodeposition from acidic sulfate solutions for 2 hours at 60 °C. A slight decrease of 3 to 4 pct in the CE was observed, when the concentration of thiourea was increased from 2 to 40 mg dm−3. The nickel deposit quality deteriorated significantly at higher thiourea concentrations; the surface morphology deteriorated and the contamination of the nickel deposits increased. The presence of thiourea affected the peak intensities of the crystal planes. Cyclic voltammetric studies on nickel deposition at 25 °C revealed depolarization behavior of the cathode at lower thiourea concentrations, ≤10 mg dm−3; however, a mixed behavior is observed at higher thiourea concentrations. These changes were also observed in the exchange current density (i 0) values.

The electrochemical corrosion behaviour of Pb-free Sn–8.5 Zn– X Ag–0.1 Al–0.5 Ga solder in 3.5% NaCl solution was investigated by using potentiodynamic polarization methods, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) analysis. The results obtained from polarization studies showed that an increase in the Ag content from 0.1 to 1.5 wt% decreased the corrosion current density ( I corr ) and shifted the corrosion potential ( E corr ) towards more noble values. These changes were also reflected in the linear polarization resistance (LPR), corrosion rate, anodic Tafel slope ( b A ) and the cathodic Tafel slope ( b c ) values, respectively. Passivation behaviour was noted in the Sn–Zn– X Ag–Al–Ga solders with Ag content > 0.1 wt%. The oxides and hydroxides of zinc were responsible for the formation of passive film. Presence of Ag atoms in the oxide layer also improved the passivation behaviour of solders to a certain extent. X-ray photoelectron spectroscopy revealed that two different oxygen species were formed on the surface films, one was assigned to OH − in Zn(OH) 2 and the other to O 2 − in ZnO. XPS depth profile results revealed that the two species had different depth distribution in the films. SEM and EDX analyses confirmed SnCl 2 as the major corrosion product formed after the electrochemical experiments.

The effect of pyridine, 2-picoline and 4-picoline on current efficiency (CE), deposit morphology, crystallographic orientation and polarization of the cathode during electrodeposition of nickel from acidic sulphate solutions containing boric acid were investigated. These additives were found to have no significant effect on current efficiency. However, the nickel deposits obtained were smoother, more compact and more leveled in case of picolines than with pyridine. The (200) plane was the most preferred plane and was not affected by the presence of these additives in the electrolyte. Each of the additives polarized the cathode with the order of polarization being 4-picoline>2-picoline>pyridine. The quality of the deposit was improved by these additives in the order 4-methyl pyridine>2-methyl pyridine>pyridine.

The effect of Al3+ on the cathodic current efficiency, deposit morphology, crystallographic orientations and polarisation behaviour of the cathode during electrodeposition of nickel from acidic sulfate solutions was investigated. Higher concentration of Al3+ (>10 mg dm−3) significantly deteriorated the surface quality of the nickel deposit as well as the current efficiency. X-ray diffraction studies revealed that the (200) plane was the most preferred crystal plane and was not affected by the presence of varying concentration of Al3+ in the electrolytic bath. The presence of Al3+ caused polarisation of the cathode, which increased with increasing Al3+ concentration. The effect of Al3+ on the electrokinetic parameters: Tafel slope (b), transfer coefficient (α) and exchange current density (i0) were also investigated.

The effect of Cd2+ on the electrodeposition of nickel from a sulphate bath in the absence and presence of boric acid has been investigated. The presence of Cd2+ ion suppresses the nickel electrodeposition and shifts the deposition potential to more negative values. The cathodic polarisation is found to depend on the composition of the electrolytic bath. For the various baths investigated, the cathodic polarization order is found to decrease in the order NiSO4+H3BO3NiSO 4+H3BO3+Na2SO4NiSO 4+Na2SO4NiSO4. For the Ni 2+ electroreduction reaction on stainless steel and nickel substrates the exchange current density decreases with increase in Cd2+ concentration in the electrolytic bath. However the Tafel slope and transfer coefficient are unaffected.

A Food and Drug Administration (FDA)/Industry/Academic Panel Discussion on multiplicity aspects of a real Phase III clinical trial was held at the Third International Conference on Multiple Comparisons, August 6, 2002, in Bethesda, Maryland. The goal was to develop some consensus among industry, government, and academic statisticians concerning requirements and methods for multiplicity management in typical clinical trials. The session was tape-recorded; this article mostly comes from an edited transcript.

The effect of Cr3+ on the cathodic current efficiency (CE), deposit morphology, crystallographic orientations and polarisation behaviour during nickel electrodeposition from acidic sulfate solutions containing boric acid was investigated. A progressive decrease in CE was seen with increase in Cr3+ concentration showing a maximum decrease in CE of ∼10-13% at concentration ∼100 mg dm-3. The presence of Cr3+ did not change the fcc structure of the electrodeposited nickel but affected the peak intensities of the crystal planes. Polarisation of the cathode was seen in the presence of Cr3+ in the electrolyte along with a shift in the electroreduction potential of nickel (II) ion towards more negative values. The effect of Cr3+ on the electrokinetic parameters: Tafel slope (b), transfer coefficient (α) and exchange current density (i0) has also been investigated.

The effect of Cd2+ on the current efficiency, surface morphology and crystallographic orientations of the electrodeposited nickel from sulfate baths of varying compositions was investigated. The results indicated that Cd2+ had no significant effect on the current efficiency but there was a noticeable change in the surface morphology and deposit quality. The X-ray diffraction studies revealed that the (200) plane was the most preferred orientation and was not generally affected by the presence of Cd2+ in the electrolytic bath.

Pocock et al. (2012, European Heart Journal 33, 176-182) proposed a win ratio approach to analyzing composite endpoints comprised of outcomes with different clinical priorities. In this article, we establish a statistical framework for this approach. We derive the null hypothesis and propose a closed-form variance estimator for the win ratio statistic in all pairwise matching situation. Our simulation study shows that the proposed variance estimator performs well regardless of the magnitude of treatment effect size and the type of the joint distribution of the outcomes.

The electrochemical reactions occurring during electrodeposition of nickel from acidic sulfate solutions were examined by cyclic and linear sweep voltammetry techniques. The effect of pyridine, 2-picoline and 4-picoline on the electrode polarization behaviour and electron transfer parameter of the cathodic reduction process was also investigated. Strongest electrode polarization was seen with 4-picoline. The order of cathodic polarization was 4-picoline > 2-picoline > pyridine. Kinetic parameters such as Tafel slope, transfer coefficient and exchange current density were determined to analyse the nature of the electrode reactions. The exchange current density for nickel deposition on nickel and stainless steel substrates was in the order 4-picoline < 2-picoline < pyridine.

The effects of pyridine and its derivatives on current efficiency, surface morphology and crystallographic orientations of electrodeposited nickel from acidic sulfate solutions were investigated. The results indicated that the presence of pyridine and picolines had no significant effect on current efficiency. The deposits obtained were smoother, more compact and uniform with picolines than with pyridine. A significant change in surface morphology of the electrodeposits was observed and picolines were found to be better additives than pyridine, 4-picoline being the best. X-ray diffraction revealed that the (200) plane was the most preferred plane and was not affected by the presence of any of these additives in the electrolyte.

The purpose of this study was to understand the possible risk of discontinuation in the context of clinical care.Rivaroxaban is noninferior to warfarin for preventing stroke in atrial fibrillation patients. Concerns exist regarding possible increased risk of stroke and non-central nervous system (CNS) thromboembolic events early after discontinuation of rivaroxaban.We undertook a post-hoc analysis of data from the ROCKET AF (Rivaroxaban Once-Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation, n = 14,624) for stroke or non-CNS embolism within 30 days after temporary interruptions of 3 days or more, early permanent study drug discontinuation, and end-of-study transition to open-label therapy.Stroke and non-CNS embolism occurred at similar rates after temporary interruptions (rivaroxaban: n = 9, warfarin: n = 8, 6.20 vs. 5.05/100 patient-years, hazard ratio [HR]: 1.28, 95% confidence interval [CI]: 0.49 to 3.31, p = 0.62) and after early permanent discontinuation (rivaroxaban: n = 42, warfarin: n = 36, 25.60 vs. 23.28/100 patient-years, HR: 1.10, 95% CI: 0.71 to 1.72, p = 0.66). Patients transitioning to open-label therapy at the end of the study had more strokes with rivaroxaban (n = 22) versus warfarin (n = 6, 6.42 vs. 1.73/100 patient-years, HR: 3.72, 95% CI: 1.51 to 9.16, p = 0.0044) and took longer to reach a therapeutic international normalized ratio with rivaroxaban versus warfarin. All thrombotic events within 30 days of any study drug cessation (including stroke, non-CNS embolism, myocardial infarction, and vascular death) were similar between groups (HR: 1.02, 95% CI: 0.83 to 1.26, p = 0.85).In atrial fibrillation patients who temporarily or permanently discontinued anticoagulation, the risk of stroke or non-CNS embolism was similar with rivaroxaban or warfarin. An increased risk of stroke and non-CNS embolism was observed in rivaroxaban-treated patients compared with warfarin-treated patients after the end of the study, underscoring the importance of therapeutic anticoagulation coverage during such a transition.

Well-structured statistical graphics help us understand subject characteristics and behavior, and their relationships to efficacy and safety of study treatment. They are increasingly being used to extract and communicate information from the clinical trial data in a lucid and succinct manner. Rapid advancements have been made in recent years in statistical visualization techniques. Statistical software such as S-PLUS™ and R provide an extensive set of tools to construct graphics to aid in the interpretation and presentation of clinical data. In this chapter, several examples are presented to demonstrate the uniquely illuminating and enlightening roles of graphics in clinical trial data analysis. Some of these graphics have played significant roles in regulatory submissions and FDA advisory committee meetings.

Graphical data exploration of clinical trial results is an imperative step prior to any model-based analyses. Thorough understanding of the raw data and the biological and statistical significances will certainly increase the likelihood of constructing a useful model and evade excessive complex data representation and overfitting. In this work, we use graphical data exploration to assess the cardiovascular safety of Drug X by estimating the propensity for the drug to alter the duration of the QT interval. We also identify model building strategies and the potential models that may be tested incrementally. Insights gained from this exercise will improve the efficiency of the model building process, communicate a clear and simple representation for complex data, and provide a useful decision making instrument for the drug development program.

Nanoscale Electrodeposition of Copper on an AFM Tip and Its Morphological Investigations