Scalable and portable implementation of the fast multipole method on parallel computers

A scalable and portable Fortran code is developed to calculate Coulomb interaction potentials of charged particles on parallel computers, based on the fast multipole method. The code has a unique feature to calculate microscopic stress tensors due to the Coulomb interactions, which is useful in constant-pressure simulations and local stress analyses. The code is applicable to various boundary conditions, including periodic boundary conditions in two and three dimensions, corresponding to slab and bulk systems, respectively. Numerical accuracy of the code is tested through comparison of its results with those obtained by the Ewald summation method and by direct calculations. Scalability tests show the parallel efficiency of 0.98 for 512 million charged particles on 512 IBM SP3 processors. The timing results on IBM SP3 are also compared with those on IBM SP4.     

Structure-Based Virtual Screening Reveals Ibrutinib and Zanubrutinib as Potential Repurposed Drugs against COVID-19

Coronavirus disease (COVID)-19 is the leading global health threat to date caused by a severe acute respiratory syndrome coronavirus (SARS-CoV-2). Recent clinical trials reported that the use of Bruton’s tyrosine kinase (BTK) inhibitors to treat COVID-19 patients could reduce dyspnea and hypoxia, thromboinflammation, hypercoagulability and improve oxygenation. However, the mechanism of action remains unclear. Thus, this study employs structure-based virtual screening (SBVS) to repurpose BTK inhibitors acalabrutinib, dasatinib, evobrutinib, fostamatinib, ibrutinib, inositol 1,3,4,5-tetrakisphosphate, spebrutinib, XL418 and zanubrutinib against SARS-CoV-2. Molecular docking is conducted with BTK inhibitors against structural and nonstructural proteins of SARS-CoV-2 and host targets (ACE2, TMPRSS2 and BTK). Molecular mechanics-generalized Born surface area (MM/GBSA) calculations and molecular dynamics (MD) simulations are then carried out on the selected complexes with high binding energy. Ibrutinib and zanubrutinib are found to be the most potent of the drugs screened based on the results of computational studies. Results further show that ibrutinib and zanubrutinib could exploit different mechanisms at the viral entry and replication stage and could be repurposed as potential inhibitors of SARS-CoV-2 pathogenesis.     

Plasma leptin is not associated with insulin resistance and proinsulin in non-diabetic South Asian Indians

In an earlier study, we observed only a weak association between plasma insulin (non-specific assay) and leptin in South Asian Indians. This was in contrast to the observations in many other ethnic groups. With the availability of measurements of specific insulin (SI) and proinsulin (PI) in the same study group, we have reanalysed the data to look for possible correlation of leptin with proinsulin and with insulin resistance calculated from the fasting values of specific insulin and glucose using the HOMA model. Subjects with normoglycaemia (n = 117) and impaired glucose tolerance (n = 27, WHO criteria) were included in the analysis. Leptin values were higher in women. Multiple linear regression analysis showed that the variations in leptin concentrations in men were associated with BMI, WHR, and 2 h SI values (R2 = 56.2%) while fasting SI and proinsulin concentrations had no significant association. In women BMI and age showed a significant association with serum leptin values (R2 = 40.1%). Univariate and multivariate analyses using insulin resistance as the dependent variable showed that it had no association with leptin in both genders. Leptin had no correlation with proinsulin also. This study confirmed that in Asian Indians the association between plasma leptin and insulin concentrations is weak and that leptin has no influence on insulin resistance. Proinsulin and leptin are also not correlated in this population. Insulin resistance shows correlation with the beta-cell function both in men and women.     

Microstructure and texture of hot-rolled Cb-Ti and V-Cb microalloyed steels with differences in formability and toughness

The relationship between microstructure and formability (also toughness) of industrially processed Cb-Ti and V-Cb steels with similar yield strength of about 600 MPa and total elongation of 20 pct was examined. The steels were processed under similar conditions and any variations in processing history were unintentional. Cb-Ti steels exhibited superior formability and toughness in relation to V-Cb steels. The improved formability and toughness of Cb-Ti steels is attributed to the cumulative contribution of relatively finer grain size, narrow ferrite grain size distribution, inherently more ductile behavior and microplasticity, the reduced intensity of {100}〈011〉 texture, and slightly higher intensity of the desired {332}〈113〉 texture.     

Direct numerical simulation of gas-solid suspensions at moderate Reynolds number: Quantifying the coupling between hydrodynamic forces and particle velocity fluctuations

Predictive device-level computational fluid dynamics (CFD) simulation of gas-solid flow is dependent on accurate models for unclosed terms that appear in the averaged equations for mass, momentum and energy conservation. In the multifluid theory, the second moment of particle velocity represents the strength of particle velocity fluctuations and is known to play an important role in the prediction of core-annular flow structure in risers (Hrenya and Sinclair, AIChEJ, 43 (4) (1994) [5]). In homogeneous suspensions the evolution of the second velocity moment is governed by the particle acceleration-velocity covariance. Therefore, fluctuations in the hydrodynamic force experienced by particles in a gas-solid flow affect the evolution of particle velocity fluctuations, which in turn can affect the mean and variance of the hydrodynamic force. This coupling has been studied in the limit of Stokes flow by Koch and co-workers using a combination of kinetic theory and multipole expansion simulations. For Reynolds numbers beyond the Stokes limit, direct numerical simulation is a promising approach to quantify this coupling. Here we present direct numerical simulation (DNS) results for the evolution of particle granular temperature and particle acceleration variance in freely evolving homogeneous gas-solid suspensions. It is found that simple extension of a class of mean particle acceleration models to their corresponding instantaneous versions does not recover the correlation of particle acceleration with particle velocity. This study motivates the development of better instantaneous particle acceleration models that are able to accurately capture the coupling between particle acceleration and velocity.     

Development and Characterization of Water-Blown Polyurethane Foams from Diethanolamides of Karanja Oil

The present study focuses on the use of renewable resource, namely karanja oil for the development of polyurethane foams. The non-edible oil was chemically modified into the diethanolamide by hydroxylation followed by transamidation. The structure of the diethanolamide was confirmed by proton nuclear magnetic resonance spectroscopy, infrared spectroscopy and gas chromatography–mass spectrometry and used as polyol to prepare water-blown polyurethane foams. Polyurethane foams were produced with carbon dioxide as the blowing agent generated by the reaction between excess polymeric MDI with water. Foams were prepared by a hand mixing process which involved blending of the diethanolamide with polypropylene glycol, polymeric MDI, water, catalyst and surfactant. The hydroxyamide content, catalyst nature and molecular weight of polypropylene glycol were varied and the effect on the properties was studied. Foam rise time and other physical properties such as density, compression strength and flexural strength were evaluated. Optical microscopy was used to study the morphology to reveal the closed cell nature and other structure–property relationships.     

Cover Picture: Nanohybrid Shish‐Kebabs: Periodically Functionalized Carbon Nanotubes (Adv. Mater. 9/2005)

Carbon nanotube (CNT)‐seeded controlled polymer crystallization provides a simple yet effective means to periodically modify CNT surfaces in work reported by Li and co‐workers on p. 1198. The cover shows CNTs periodically decorated with polyethylene single crystals, with a periodicity of ～50–70 nm. Both single‐ and multiwalled CNTs have been successfully decorated with polyethylene and Nylon 6,6, implying that coupling crystalline polymers with functional groups might be a generic method for CNT functionalization in an ordered and controlled manner.     

Synthesis of Thumba,Castor and Sal Fatty Ethanolamide-Based Anionic Surfactants

The study involved the preparation and evaluation of anionic surfactants from non-edible oil based thumba (containing unsaturated-rich fatty acids, 80.9 %), castor (containing ricinoleic acid, a hydroxy fatty acid 89.3 %) and sal (containing saturated-rich fatty acids, 56.5 %). The oils extracted from these seeds (using Soxhlet) were reacted with monoethanolamine and diethanolamine to get corresponding fatty mono- and diethanolamides. The ethanolamides were sulfated using chlorosulfonic acid and the sulfated sodium salts were evaluated for surfactant properties namely surface tension, critical micelle concentration (CMC), emulsifying property, wetting, foaming power and calcium tolerance. The properties were compared with sodium dodecyl sulfate (SDS) a well known anionic surfactant. Among the different sulfated sodium salts of ethanolamides, thumba showed superior surfactant properties compared to castor and sal. Sulfated sodium salt of thumba monoethanolamide showed better properties (CMC, 0.035 mmol/L, surface tension 30.2 mN/m and calcium tolerance >1,000 ml, 0.5 % calcium acetate solution) compared to sulfated sodium salts of thumba diethanolamides, followed by sulfated sodium salts of castor monoethanolamide (CMC 0.037 mmol/L, surface tension 35.3 mN/m and calcium tolerance >1,000 ml, 0.5 % calcium acetate solution). Sal being saturated rich was not properly soluble in water and showed poor surfactant properties compared to the other two. Also the sulfated sodium salts of thumba and castor ethanolamides exhibited superior properties compared to SDS.