Early‐stage oxidation behavior of Co‐rich high‐temperature alloys

The long‐term oxidation performance of an alloy is critically linked to the early‐stage oxidation behavior of high‐temperature alloys. This study investigates early‐stage oxidation behavior in terms of oxidation kinetics, scale evolution, and residual stresses developed within a scale of the commercially available cobalt‐rich alloys: HAYNES® 188, 6B, 25, and HR‐160® and a newly developed nitride‐dispersion strengthened NS‐163® alloy (HAYNES®, HR‐160®, NS‐163® are registered trademarks of Haynes International, Inc). Short‐term isothermal oxidation exposures were conducted in flowing air at 982 °C for durations of 1–50 h. Oxidation kinetics was assessed by weight‐change behavior, which showed that 188 alloy exhibited the lowest weight‐gain, while for similar times HR‐160 alloy underwent weight‐loss. SEM/EDS analysis was performed to characterize oxides formed in these alloys, while stresses developed in the oxides of different alloys were measured using synchrotron X‐ray radiation. The results in this paper clearly demonstrated the effects of alloy composition on the scale evolution and the amount of stresses developed in oxides.     

Alveolar Regeneration in COVID-19 Patients: A Network Perspective

A viral infection involves entry and replication of viral nucleic acid in a host organism, subsequently leading to biochemical and structural alterations in the host cell. In the case of SARS-CoV-2 viral infection, over-activation of the host immune system may lead to lung damage. Albeit the regeneration and fibrotic repair processes being the two protective host responses, prolonged injury may lead to excessive fibrosis, a pathological state that can result in lung collapse. In this review, we discuss regeneration and fibrosis processes in response to SARS-CoV-2 and provide our viewpoint on the triggering of alveolar regeneration in coronavirus disease 2019 (COVID-19) patients.     

CO2 Hydrogenation over Ru-NPs Supported Amine-Functionalized SBA-15 Catalyst: Structure–Reactivity Relationship Study

Catalysis Letters - We gave an effective protocol to support Ru NPs on amine-functionalized SBA-15 mesoporous silica to catalyze the CO2 hydrogenation reaction. The amine groups present in the...     

Investigations of AB5-type hydrogen storage materials with enhanced hydrogen storage capacity

The present study deals with investigations on synthesis, characterization and hydrogenation behavior of the MmNi₅-type hydrogen storage alloys Mm_0.9Ca_0.1Ni_4.9−xFe_xAl_0.1 (x = 0, 0.1, 0.2 and 0.3). All the alloys are synthesized by radio frequency induction melting following the composite pellet route. The X-ray diffraction pattern of dehydrogenated alloy without iron, detects peaks corresponding to calcium hydride, which are absent in the XRD pattern of the alloy with iron. The hydrogenation behavior is monitored by means of activation curves, absorption-desorption pressure-composition isotherms, hysteresis factors and desorption kinetic curves. The substitution of Iron at the place of nickel in the alloys Mm_0.9Ca_0.1Ni_4.9−xFe_xAl_0.1 (x = 0, 0.1, 0.2 and 0.3) gives an increase in the hydrogen storage capacity as 1.82, 1.90, 2.2 and 1.95 wt% corresponding to x = 0, 0.1, 0.2 and 0.3 respectively. The correlation between structural characteristics and hydrogenation behavior is described and discussed.     

Effects of nano size mischmetal and its oxide on improving the hydrogen sorption behaviour of MgH2

This paper reports the catalytic effects of mischmetal (Mm) and mischmetal oxide (Mm-oxide) on improving the dehydrogenation and rehydrogenation behaviour of magnesium hydride (MgH₂). It has been found that 5 wt.% is the optimum catalyst (Mm/Mm-oxide) concentration for MgH₂. The Mm and Mm-oxide catalyzed MgH₂ exhibits hydrogen desorption at significantly lower temperature and also fast rehydrogenation kinetics compared to ball-milled MgH₂ under identical conditions of temperature and pressure. The onset desorption temperature for MgH₂ catalyzed with Mm and Mm-oxide are 323 °C and 305 °C, respectively. Whereas the onset desorption temperature for the ball-milled MgH₂ is 381 °C. Thus, there is a lowering of onset desorption temperature by 58 °C for Mm and by 76 °C for Mm-oxide. The dehydrogenation activation energy of Mm-oxide catalyzed MgH₂ is 66 kJ/mol. It is 35 kJ/mol lower than ball-milled MgH₂. Additionally, the Mm-oxide catalyzed dehydrogenated Mg exhibits faster rehydrogenation kinetics. It has been noticed that in the first 10 min, the Mm-oxide catalyzed Mg (dehydrogenated MgH₂) has absorbed up to 4.75 wt.% H₂ at 315 °C under 15 atmosphere hydrogen pressure. The activation energy determined for the rehydrogenation of Mm-oxide catalyzed Mg is ∼62 kJ/mol, whereas that for the ball-milled Mg alone is ∼91 kJ/mol. Thus, there is a decrease in absorption activation energy by ∼29 kJ/mol for the Mm-oxide catalyzed Mg. In addition, Mm-oxide is the native mixture of CeO₂ and La₂O₃ which makes the duo a better catalyst than CeO₂, which is known to be an effective catalyst for MgH₂. This takes place due to the synergistic effect of CeO₂ and La₂O₃. It can thus be said that Mm-oxide is an effective catalyst for improving the hydrogen sorption behaviour of MgH₂.     

Studies on protein and its high‐molecular‐weight subunit composition in relation to chapati‐making quality of Indian wheat cultivars

In order to predict the suitability of wheat for chapati making, 15 Indian wheat cultivars were studied for various protein characteristics in relation to chapati‐making quality. The cultivars varied considerably in their protein characteristics and chapati‐making potential. Results clearly indicated that both quantitative and qualitative characteristics of proteins influenced the chapati‐making potential of cultivars. Puffed height, the important qualitative parameter of chapati, was positively correlated with protein content (r = 0.62, p < 0.05), gluten content (r = 0.79, p < 0.01), sodium dodecyl sulphate (SDS) sedimentation value (r = 0.57, p < 0.05) and Glu‐1 quality scores of high‐molecular‐weight (HMW) subunits (r = 0.66, p < 0.01). Overall quality score of chapati was positively correlated with gluten content (r = 0.64, p < 0.01), SDS sedimentation value (r = 0.60, p < 0.05) and Glu‐1 score (r = 0.58, p < 0.05). HMW subunit composition varied considerably among cultivars. Cultivars having 5 + 10 subunits at the Glu‐1D chromosome, a protein content of about 130 g kg^?1 and SDS sedimentation value around 75 ml yielded excellent chapatis, while those having 2 + 12 subunits, a protein content of about 115 g kg^?1 and SDS sedimentation value around 55 ml resulted in poor chapatis. Interestingly, the presence of the 1BL/1RS chromosome in cultivars had no adverse effect on chapati quality. © 2003 Society of Chemical Industry     

GEL FORMATION IN VACUUM GAS OIL. I. ROLE OF COMPOSITION

The compositional analysis of aromatics, saturates and urea non adductables obtained from vacuum gas oil (VGO) distillate (370-550°C) and its seven sub-fractions: (1) 370-400, (2) 400-425, (3) 425-450, (4) 450-475, (5) 475-500, (6) 500-525 and (7) 525-550°C, derived from both paraffinic and aromatic base crude oils have been done using thin layer chromatography/flame ionisation detection technique. The physico- chemical characteristics are measured using the ASTM/ standard test procedures and an attempt has been made to correlate the physico-chemical properties with the composition. The phenomenon of gel formation at low temperatures and the characteristics of the gel in these VGO sub-fractions have been studied by X-ray diffractometry and photomicrography. It is found that at low temperatures the gel formation takes place due to the development of a three dimensional network by the crystallizing n-paraffins, as well as by the agglomeration of molecules due to very high viscosity. Both processes proceed simultaneously and the concentration and composition of n-paraffins have been found to determine the dominance or otherwise of the crystallization process.     

On the computer simulation of the P–C isotherms of ZrFe2 type hydrogen storage materials

This paper deals with computer simulation of the P–C isotherms of some ZrFe₂ type (Zr(Fe_1−xCr_x)₂, Zr_1−xTi_xFe_1.4Cr_0.6, Zr_1−2xMm_xTi_xFe_1.4Cr_0.6 : x00.4) of hydrogen storage materials. A feasible mathematical model has been developed to simulate the P–C isotherms. The randomized variables in the model applied for simulating the P–C isotherms of the above-mentioned ZrFe₂ type hydrogen storage materials correspond to change in enthalpy (ΔH) and entropy (ΔS) of hydride formation. Several ZrFe₂ type materials as in above have been synthesized and their P–C isotherms, enthalpy and entropy change has been evaluated experimentally in order to have input data for simulation. A special software was developed to simulate the P–C isotherms using the said model. A close match between the experimentally observed and simulated P–C isotherms for the above said ZrFe₂ type alloys has been obtained.     

Basics: Current base oil quality and technological options for its improvement— an Overview

Recent technological developments have revolutionised the lubricant industry by spurring a widespread quality improvement in both base oils and additives, giving superior finished lubricants. The upgrading of base oils is being brought about by more demanding requirements from original equipment manufacturers (OEMs), by government regulations, and through consumer awareness, environmental concerns, decreasing supply of high‐quality lubricant‐bearing crudes, and expanding markets worldwide. Present‐day lubricant demand is for maximum oxidation stability, superior low‐temperature performance, low volatility, and improved additive response, which are difficult to achieve through conventional processing. Conventional solvent lubricant refining produces base oils with a viscosity index (VI) of 100 with a fair amount of sulphur and aromatics, i.e., Group I base oils only. The current requirements of high‐performance base oils can conveniently be met through the hydroprocessing route. Depending upon the severity level, hydroprocessing is able to produce base oils of VI 95–110, in addition to low sulphur and high saturates content (Group II and Group III) by transforming the undesirable molecules into more useful structures. In countries such as India, a hybrid approach offers a technical solution to meet current demands for lubricant quality. This approach can be implemented in existing lubricant refineries without entailing major changes in refinery configuration, besides being cost‐effective. This paper describes the current requirements of modern lubricants in relation to API Groups and trends in these, and describes a sequence of technologies involving solvent refining, a cost‐effective hybrid scheme, and more recent hydroprocessing that allows a cost‐effective upgrading of Group I refining process. A case study is given that discusses the adoption of the hybrid scheme in Indian refineries.     

Mie‐Resonant Membrane Huygens' Metasurfaces

All‐dielectric metasurfaces have become a new paradigm for flat optics as they allow flexible engineering of the electromagnetic space of propagating waves. Such metasurfaces are usually composed of individual subwavelength elements embedded into a host medium or placed on a substrate, which often diminishes the quality of the resonances. The substrate imposes limitations on the metasurface functionalities, especially for infrared and terahertz frequencies. Here a novel concept of membrane Huygens' metasurfaces is introduced. The metasurfaces feature an inverted design, and they consist of arrays of holes made in a thin membrane of high‐index dielectric material, with the response governed by the electric and magnetic Mie resonances excited within dielectric domains of the membrane. Highly efficient transmission combined with the 2π phase coverage in the freestanding membranes is demonstrated. Several functional metadevices for wavefront control are designed, including beam deflector, a lens, and an axicon. Such membrane metasurfaces provide novel opportunities for efficient large‐area metadevices, whose advanced functionality is defined by structuring rather than by chemical composition.