Gas Hydrate Formation in Reversed Micelles

We describe a technique to modify protein solubility and optimize enzyme activity in reversed micellar solutions. The technique is based on the ability of hydrates of natural gas to form in the micro-aqueous phase. Clathrate hydrates are crystalline inclusions of water and gas, and their formation in bulk water has traditionally been studied with relevance to natural gas recovery. We have found that hydrates can form in the environment of the microaqueous pools of reversed micelles, and that their extent of formation can be well controlled through the thermodynamic variables of temperature and pressure. Additionally, formation of hydrates affects the size and aggregation number of the micelles, and thus influences the solubility and conformation of encapsulated proteins. We demonstrate how the concept can be used in two applications: (i) protein extraction into reversed micelles and subsequent recovery, and (ii) optimization of enzyme activity in reversed micelles.     

Topological estimation of proton-ligand formation constants of potential antitumour agents: Salicylhydroxamic acids

Proton-ligand formation constants of salicylhydroxamic acids (SHA) and their nuclear substituted derivatives have been estimated topologically using the normalized Wiener index, referred to as mean square Wiener index (Wms). Regression analysis of the data indicates that Wms can be used successfully for estimating and monitoring proton-ligand formation constants.     

Depopulation of low‐Rydberg Na atom in collisions with rare gases: A molecular‐state treatment

Total quenching of the low‐Rydberg state of Na in collision with thermal Ne and Ar was investigated, for the first time, employing a molecular approach in the impact parameter formalism. A large basis set of Slater‐type orbitals was used to calculate the molecular structure of the transient quasimolecule formed during the collision; pseudopotentials were used to incorporate the effective binding of the distant electron. A 14‐channel calculation was carried out to evaluate the total depopulation cross sections for Na(9s) colliding with the ground‐state Ne and Ar atoms in the thermal‐energy region. The two colliding pairs not only differ from each other, but also show wide variations from the previously studied Na He pair, in terms of details of the collision dynamics. In the case of the Na Ar system, a unique feature that leads to appreciably larger quenching cross sections shows qualitative agreement with the measurement. A comparative study of three (He/Ne/Ar Na) colliding pairs reveals that the simplified approach like the free‐electron model or the impulse approximation fails to provide details of such state‐changing reactions. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 307–316, 1999     

Electric field gradients in various chemical environments of133Ba by the sum peak method

The sum peak at 437 keV (356+81 keV) has been measured in various chemical and physico-chemical environments. The fact that the intensity ratio of the sum peak to its single peak changes with the circumstances in which the radioactive source is placed is used to observe the effect of the chemical environment on directional correlation coefficients of 351–81 keV cascade in¹³³Ba−¹³³Cs decay and to detect the variations in the electric field gradient in different barium compounds. The sum peak method has been found to be useful in describing the chemical influences onG ₂₂ parameters and hence in the study of electric field gradients.     

Oxidative degradation of levofloxacin by water-soluble manganese dioxide in aqueous acidic medium: a kinetic study

Pharmaceuticals, especially fluoroquinolone antibiotics, have received increasing global concern, due to their intensive use in the environment and potential harm to ecological system as well as human health. Degradation of antibiotics, such as oxidative degradation by metal oxides, often plays an important role in the elimination of antibiotics from the environment. The kinetics of oxidation of levofloxacin by water-soluble manganese dioxide has been studied in aqueous acidic medium at 25 °C temperature. The stoichiometry for the reaction indicates that the oxidation of 1 mol of levofloxacin requires 1 mol of manganese dioxide. The reaction is second order, that is first order with respect to manganese dioxide and levofloxacin. The rate of reaction increases with the increasing [H⁺] ion concentration. A probable reaction mechanism, in agreement with the observed kinetic results, has been proposed and discussed. The energy and enthalpy of activation have been calculated to be 30.54 and 28.07 kJ mol^?1, respectively.     

Resilient and agile engineering solutions to address societal challenges such as coronavirus pandemic

The world is witnessing tumultuous times as major economic powers including the US, UK, Russia, India, and most of Europe continue to be in a state of lockdown. The worst-hit sectors due to this lockdown are sales, production (manufacturing), transport (aerospace and automotive) and tourism. Lockdowns became necessary as a preventive measure to avoid the spread of the contagious and infectious “Coronavirus Disease 2019” (COVID-19). This newly identified disease is caused by a new strain of the virus being referred to as Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS CoV-2; formerly called 2019-nCoV). We review the current medical and manufacturing response to COVID-19, including advances in instrumentation, sensing, use of lasers, fumigation chambers and development of novel tools such as lab-on-the-chip using combinatorial additive and subtractive manufacturing techniques and use of molecular modelling and molecular docking in drug and vaccine discovery. We also offer perspectives on future considerations on climate change, outsourced versus indigenous manufacturing, automation, and antimicrobial resistance. Overall, this paper attempts to identify key areas where manufacturing can be employed to address societal challenges such as COVID-19.     

Stability-Indicating LC–PDA Method for Determination of Picrosides in Hepatoprotective Indian Herbal Preparations of Picrorhiza kurroa

A liquid chromatography method was developed and validated for the determination of picroside-I and picroside-II in herbal preparations containing Picrorhiza kurroa as one of the ingradients. Resolution of picrosides was achieved on a reversed phase (C-18) endcapped bidentate column by using a mobile phase of acetonitrile: water (25:75 v/v). The detection of picrosides was carried out at 270 nm. The method was validated for precision, accuracy and robustness according to the International Conference on Harmonization (ICH) guidelines and is applicable for the quality control of preparations containing P. kurroa. Analysis of samples in forced degradation proved it to be applicable for stability evaluation. The linear regression analysis data showed good linear relationship (r ² = 0.9999 ± 0.0010 for picroside-I and 0.9997 ± 0.0012 for picroside-II) in the concentration range of 0.4–4.0 μg. The limit of detection and quantification for picroside-I and picroside-II were recorded to be 28.1 and 73.1 ng and 85.2 and 221.5 ng, respectively. Satisfactory recovery results were observed from the herbal preparations (97.5–100.5%). Intra- and inter- day precision of the method was acceptable, with relative standard deviation (%RSD) values in the range of 0.04–1.16% and 0.03–0.27%, respectively.     

Determination of oxytocin in milk of cows administered oxytocin

To address people's concerns of exogenous oxytocin (OT) administration to lactating bovines, a study was undertaken to (a) establish an enzyme immunoassay (EIA) for OT determination in milk, (b) quantify OT in milk of cows administered OT, and (c) study influence of pasteurization on OT stability in milk. A sensitive EIA validated according to the criteria of European Union—Decision 2002/657/EC was developed for OT in skim milk in an analytical range of 10-250 pg mL⁻¹ with a decision limit (CCα) of 30 pg mL⁻¹ and detection capability (CCβ) of 41.5 pg mL⁻¹. Milk samples collected from cows (n = 38) administered either 25 or 50 IU OT prior to milking were investigated for the presence of OT. There was no significant difference among both groups with the mean concentrations of OT being 15.8 and 14.9 pg mL⁻¹ for cows subjected to 25 and 50 IU OT administration, respectively. The OT levels in skim milk of control cows (n = 30; untreated) were basal (around 10 pg mL⁻¹). All the analyzed milk samples were below the CCα value of 30 pg mL⁻¹. Pasteurization of OT spiked milk samples at different temperature and sample holding conditions reduced the immunological activity of OT to 43% at 110 °C. However, no further decline occurred in the immunological activity with increased pasteurization temperature and time. It was concluded that the milk OT concentrations after OT administrations were minimal and below the assay decision limit. However, OT was quite stable to pasteurization in OT spiked milk.     

Is it True That the Normal Valence‐Length Correlation Is Irrelevant for Metal–Metal Bonds?

The most intriguing feature of metal–metal bonds in inorganic compounds is an apparent lack of correlation between the bond order and the bond length. In this study, we combine a variety of literature data obtained by quantum chemistry and our results based on the empirical bond valence model (BVM), to confirm for the first time the existence of a normal exponential correlation between the effective bond order (EBO) and the length of the metal–metal bonds. The difference between the EBO and the formal bond order is attributed to steric conflict between the (TM)_n cluster (TM=transition metal) and its environment. This conflict, affected mainly by structural type, should cause high lattice strains, but electron redistribution around TM atoms, evident from the BVM calculations, results in a full or partial strain relaxation.