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Acidic gases such as H2S and CO2 are generated in the refineries during coal gasification. These pollutant gases need to be treated before releasing to the atmosphere. Conventionally, H2S gas is treated by Claus process in which H2S is converted to elemental S and H2O, in presence of O2 at ∼1,200 K. In the present energy scenarios, hydrogen has got importance as a source of clean fuel for industrial application. The H2S generated in the refineries can be a potential precursor of hydrogen. If this hydrogen can be obtained by thermal decomposition of H2S, that can increase the overall economic value of the H2S containing streams and the produced hydrogen can be used for hydrocracking and hydro-treating in refineries, as well as to synthesize value-added products for chemical industries. However, H2S thermal decomposition is an endothermic and equilibrium limited reaction (equilibrium conversion is only ∼15 % at 1,000 K), requiring a very high temperature (∼1,500 K) to achieve even a conversion of greater than 40 %. Packed Bed Catalytic Membrane Reactor (PBCMR) for thermal decomposition of H2S can be a potential technology augmentation and process intensification to increase this equilibrium conversion. In this work, modeling and experimental studies of H2S thermal decomposition using in-house designed & developed PBCMR have been carried out. The modeling studies were validated with experimental data. Clay-alumina ceramic tubular membrane (L: 250 mm; OD: 12 mm; thickness: 2 mm) was fabricated using extrusion process having an average membrane pore size of ∼1 μm and with a porosity of ∼20 %. Pt (2 %) coated alumina extrudes were used as catalyst to accelerate the reaction kinetics. Experimental studies showed that H2S to hydrogen conversion of ∼90 % is achieved using PBCMR at ∼1,523 K, compared to only ∼40 % conversion in a conventional packed bed tubular reactor (without membrane). Modelling studies were carried out to study the influence of operating parameters such as, reactor wall temperature, feed temperature, pressure and feed velocity. Studies showed that reactor wall temperature is having the most dominant effect on H2S conversion, which is confirmed by experimental findings. The studies offer useful insights into the application of PBCMR technology for management of waste gas stream containing H2S and recovery of hydrogen. [ABSTRACT FROM AUTHOR]

The hydrogen in the vent gas stream of the hydrocracker (used to produce bio-jet fuel) cannot be reused since it has many impurities. The metal membrane can be a potential candidate for recovering hydrogen from this vent gas. In this work, the authors report the development of a composite palladium membrane and its application, for the first time, in the recovery of hydrogen from a simulated vent gas environment. A dense thin film (thickness ~3 µm) of Pd metal was coated on a ceramic support tube by the sputter deposition technique. The hydrogen permeance of the Pd membrane was found to be 18.75 × 10-6 mol·m-2·h-1·Pa-1, which was reduced to 3.25 × 10-6 mol·m-2·h-1·Pa-1, with an exposure of 100 h in the simulated bio-jet fuel environment. To avoid the loss of permeability, a thin layer of Pt can be coated over the Pd membrane. The present study used MATLAB software to simulate the Pt-coated Pd composite membrane performance in the bio-jet fuel production environment. Simulation studies confirmed that a membrane area of ~95 cm² (250 mm length and 12 mm OD) is sufficient for the complete recovery of hydrogen from the vent gas stream of hydrocracker at a feed velocity of 0.075 m/s. [ABSTRACT FROM AUTHOR]

Key Points: Question: How does once-weekly insulin icodec compare with once-daily insulin degludec in glucose-lowering efficacy (hemoglobin A1c [HbA1c]) in people with insulin-naive type 2 diabetes? Findings: In this randomized, double-masked, double-dummy trial that enrolled 588 people with type 2 diabetes, estimated mean HbA1c change from baseline to week 26 was noninferior with insulin icodec (−1.6 percentage points) compared with insulin degludec (−1.4 percentage points), with confirmed statistical superiority (estimated treatment difference, −0.2 percentage points). Meaning: The results demonstrate the efficacy of once-weekly insulin icodec treatment in people with insulin-naive type 2 diabetes. Importance: Once-weekly insulin icodec could provide a simpler dosing alternative to daily basal insulin in people with type 2 diabetes. Objective: To evaluate the efficacy and safety of once-weekly icodec vs once-daily insulin degludec in people with insulin-naive type 2 diabetes. Design, Setting, and Participants: Randomized, double-masked, noninferiority, treat-to-target, phase 3a trial conducted from March 2021 to June 2022 at 92 sites in 11 countries in adults with type 2 diabetes treated with any noninsulin glucose-lowering agents with hemoglobin A1c (HbA1c) of 7%-11% (53-97 mmol/mol). Interventions: Participants were randomly assigned in a 1:1 ratio to receive either once-weekly icodec and once-daily placebo (icodec group; n = 294) or once-daily degludec and once-weekly placebo (degludec group; n = 294). Main Outcomes and Measures: The primary end point was change in HbA1c from baseline to week 26 (noninferiority margin, 0.3% percentage points). Secondary end points included change in fasting plasma glucose from baseline to week 26, mean weekly insulin dose during the last 2 weeks of treatment, body weight change from baseline to week 26, and number of level 2 (clinically significant; glucose level <54 mg/dL) and level 3 (severe; requiring external assistance for recovery) hypoglycemic episodes. Results: Among 588 randomized participants (mean [SD] age, 58 [10] years; 219 [37%] women), 564 (96%) completed the trial. Mean HbA1c level decreased from 8.6% (observed) to 7.0% (estimated) at 26 weeks in the icodec group and from 8.5% (observed) to 7.2% (estimated) in the degludec group (estimated treatment difference [ETD], −0.2 [95% CI, −0.3 to −0.1] percentage points), confirming noninferiority (P <.001) and superiority (P =.002). There were no significant differences between the icodec and degludec groups for fasting plasma glucose change from baseline to week 26 (ETD, 0 [95% CI, −6 to 5] mg/dL; P =.90), mean weekly insulin dose during the last 2 weeks of treatment, or body weight change from baseline to week 26 (2.8 kg vs 2.3 kg; ETD, 0.46 [95% CI, −0.19 to 1.10] kg; P =.17). Combined level 2 or 3 hypoglycemia rates were numerically higher in the icodec group than the degludec group from week 0 to 31 (0.31 vs 0.15 events per patient-year exposure; P =.11) and statistically higher in the icodec group from week 0 to 26 (0.35 vs 0.12 events per patient-year exposure; P =.01). Conclusions and Relevance: Among people with insulin-naive type 2 diabetes, once-weekly icodec demonstrated superior HbA1c reduction to once-daily degludec after 26 weeks of treatment, with no difference in weight change and a higher rate of combined level 2 or 3 hypoglycemic events in the context of less than 1 event per patient-year exposure in both groups. Trial Registration: ClinicalTrials.gov Identifier: NCT04795531 This randomized clinical trial examines the efficacy and safety of once-weekly icodec vs once-daily insulin degludec in people with insulin-naive type 2 diabetes. [ABSTRACT FROM AUTHOR]

In this work, for the first time, the authors report polyethylene terephthalate (PET) track-etched membrane fabrication and detailed quantitative parametric studies for its application in He-N2 separation. The study also covers theoretical studies to understand the irradiation of PET film with ions as well as the contribution of gas flow domains, which is attempted for the first time. Monte Carlo simulations were carried out using the FLUKA code to evaluate the dose deposited by the ions in the PET film and the displacement per atom (DPA). The distribution of absorbed dose in the film as a function of thickness, the mean absorbed dose as a function of ion energy, and DPA at various depths in the film was determined using these simulations. The range of various ion beams was also calculated using the SRIM code. The effect of incident energy of irradiation beam (Si: 70 and 90 MeV and Cl: 84, 100 and 115 MeV) and etching parameters like concentration of NaOH, temperature, UV radiation, and ultrasonication on the control and irradiated polymer films (~25 µm thickness) were studied. Gas permeation studies of in-house synthesized track etched membrane (optimum) were carried out and a promising He/N2 selectivity of ~2.4 was achieved. The results confirmed that the membranes can have a potential application in the separation of He from natural gas. [ABSTRACT FROM AUTHOR]

One-dimensional (1-D) ZnO nanostructure arrays, such as nanowires, nanonails and nanotrees, are synthesized by oxygen assisted thermal evaporation of metallic zinc on a quartz substrate over a large area. The optical and electrical properties of the ZnO nanowire and nanonail arrays and also the applicability of these ZnO 1-D nanoform arrays as gas sensors are investigated.

CdS one-dimensional nanoforms, such as nanowires, nanoribbons, networklike nanowires, pearl necklace type nanowires, helical-like nanowires and nanowire arrays, are formed on Si substrates by a simple thermal evaporation process. Optical absorbance, photoluminescence and Raman spectroscopy are used to investigate the physical and structural quality of these CdS nanoforms.

Rapid production of single crystalline CdS nanoribbions with hexagonal wurtzite phase is achieved by thermal evaporation of CdS powder on Si wafers. The role of flow rate of the Ar gas and the temperature on the size and shape of the CdS nanoribbons are studied.

Cerium oxide (ceria) contains two stable states of cerium ions (Ce3+ and Ce4+). The presence of these two states and the ability to swap from one state to another (Ce3+ ↔ Ce4+) by scavenging the highly reactive oxygen species (ROS) generated from radiolysis of water, ensure the enhanced stability of polysulfone (Psf) membranes in the γ-radiation environment. In this study, the ROS scavenging ability of ceria was studied. Ceria nanoparticles were found to scavenge ROS like hydroxyl radicals and hydrogen peroxide (H2O2). The H2O2 scavenging is due to the peroxidase-like catalytic activity of ceria nanoparticles. The ROS scavenging is responsible for offering protection to the Psf host matrix and in turn the stability to the Psf-ceria mixed-matrix membranes (MMMs) in γ-radiation environment. Thus, presence of ceria nanoparticles provides an opportunity for utilizing Psf-ceria MMMs in ionizing radiation environment with increased life span, without compromise in the performance. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) samples in the form of hexagonal-based bipyramids and particles of nanometer dimensions were synthesized through solvothermal route and characterized by x-ray diffraction and transmission electron microscopy. Positron annihilation experiments were performed to study the structural defects such as vacancies and surfaces in these nanosystems. From coincidence Doppler broadening measurements, the positron trapping sites were identified as Zn vacancies or Zn–O–Zn trivacancy clusters. The positron lifetimes, their relative intensities, and the Doppler broadened lineshape parameter S all showed characteristic changes across the nanobipyramid size corresponding to the thermal diffusion length of positrons. In large nanobipyramids, vacancies within the crystallites also trapped positrons and the effects of agglomeration of such vacancies due to increased temperatures of synthesis were reflected in the variation of the annihilation parameters with their base diameters. The sizes of the nanoparticles used were all in the limit of thermal diffusion length of positrons and the annihilation characteristics were in accordance with the decreasing contribution from surfaces with increasing particle size. [ABSTRACT FROM AUTHOR]

Nanostructures of ZnS, both particles and rods, were synthesized through solvothermal processes and characterized by x-ray diffraction and high resolution transmission electron microscopy. Positron lifetime and Doppler broadening measurements were made to study the features related to the defect nanostructures present in the samples. The nanocrystalline grain surfaces and interfaces, which trapped significant fractions of positrons, gradually disappeared during grain growth, as indicated by the decreasing fraction of orthopositronium atoms. The crystal vacancies present within the grains also trapped positrons. These vacancies further agglomerated into clusters during the thermal treatment given to effect grain growth. The positron lifetime was remarkably large at extremely small grain sizes (∼1.5 nm) and this was attributed to the occurrence of quantum confinement effects, as verified through optical absorption measurements. Positron lifetimes in ZnS nanorods increased with increasing content of cubic phase in the samples and this observation is assigned to the annihilation of positrons in sites with increased cubic unit cell volume. The Doppler broadened spectra also indicated qualitative changes consistent with these observations. [ABSTRACT FROM AUTHOR]