The Lanczos method applied to quasi-static stark broadening of spectral lines

The quasi-static ion approximation of Stark broadened spectral lines involves an average of the field-dependent line shape over the microfield probability distribution. In the conventional approach, this can become computationally expensive since the calculation at each field point requires inverting a possibly large matrix. It is shown that these calculations are well suited to the “Padé Via Lanczos” approach, which allows for an efficient and accurate numerical integration over the quasi-static field. In turn, the integration forms the basis for determining convergence with Lanczos iterations. Simple examples are used to demonstrate improved performance over conventional methods.     

A Platform Approach to Protein Encapsulates with Controllable Surface Chemistry

The encapsulation of proteins into core-shell structures is a widely utilised strategy for controlling protein stability, delivery and release. Despite the recognised utility of these microstructures, however, core-shell fabrication routes are often too costly or poorly scalable to allow for industrial translation. Furthermore, many scalable routes rely upon emulsion-techniques implicating denaturing or environmentally harmful organic solvents. Herein, we investigate core-shell protein encapsulation through single-feed, aqueous spray drying: a cheap, industrially ubiquitous particle-formation technology in the absence of organic solvents. We show that an excipient’s preference for the surface of the spray dried particle is well-predicted by its hydrodynamic diameter (Dh) under relevant feed buffer conditions (pH and ionic strength) and that the predictive power of Dh is improved when measured at the spray dryer outlet temperature compared to room temperature (R2 = 0.64 vs. 0.59). Lastly, we leverage these findings to propose an adaptable design framework for fabricating core-shell protein encapsulates by single-feed aqueous spray drying.     

Chemistry,Biosynthesis and Pharmacology of Sarsasapogenin: A Potential Natural Steroid Molecule for New Drug Design,Development and Therapy

Sarsasapogenin is a natural steroidal sapogenin molecule obtained mainly from Anemarrhena asphodeloides Bunge. Among the various phytosteroids present, sarsasapogenin has emerged as a promising molecule due to the fact of its diverse pharmacological activities. In this review, the chemistry, biosynthesis and pharmacological potentials of sarsasapogenin are summarised. Between 1996 and the present, the relevant literature regarding sarsasapogenin was obtained from scientific databases including PubMed, ScienceDirect, Scopus, and Google Scholar. Overall, sarsasapogenin is a potent molecule with anti-inflammatory, anticancer, antidiabetic, anti-osteoclastogenic and neuroprotective activities. It is also a potential molecule in the treatment for precocious puberty. This review also discusses the metabolism, pharmacokinetics and possible structural modifications as well as obstacles and opportunities for sarsasapogenin to become a drug molecule in the near future. More comprehensive preclinical studies, clinical trials, drug delivery, formulations of effective doses in pharmacokinetics studies, evaluation of adverse effects and potential synergistic effects with other drugs need to be thoroughly investigated to make sarsasapogenin a potential molecule for future drug development.     

Chiral separation and thermodynamic investigation of WCK 3023: A novel oxazolidinone antibacterial agent,application to pre‐clinical pharmacokinetic study

A chiral liquid chromatographic method was developed and validated for the quantification of R‐enantiomer impurity (RE) in WCK 3023 (S‐enantiomer), a new drug substance. The separation was achieved on Chiralpak IA (amylose‐based immobilized chiral stationary phase), using a mobile phase consisting of n‐hexane–ethanol–trifluoroacetic acid (70:30:0.2, v/v/v) at a flow rate of 1.0 mL/min. The method was extensively validated for the quantification of RE in WCK 3023 and proved to be robust. For RE the detector response was linear over the concentration range of 0.11–5 μg/mL. The limit of quantitation and limit of detection for RE were 0.11 and 0.04 μg/mL respectively. Average recovery of the RE was in the range of 98.11–99.55%. The developed method was specific, sensitive, precise and accurate for quantitative determination of RE in WCK 3023. The impact of thermodynamic parameters on the chiral separation was evaluated. The method was employed for controlling the enantiomeric impurity in the lots of WCK 3023 used for pre‐clinical studies. The method was successfully applied to evaluate the possible conversion of WCK 3023 to RE in rat serum samples during pre‐clinical pharmacokinetic studies.     

Stereoselective synthesis of 3,4-di-substituted mercaptolactones via photoredox-catalyzed radical addition of thiophenols

A visible light mediated radical addition of thiophenols on 4-phenylbut-3-enoic acids to give diastereoselective synthesis of 3,4-disubstituted γ-lactones is reported. The reaction precludes the conventional prerequisite of conjugate addition. Furthermore, the lactones were successfully utilized in the synthesis of γ-ketoamides.     

Exploration of superhalogen nature of Pt(CN)n complexes (n = 1–6) and their abilities to form supersalts and superacids: a DFT–D3 study

Structural Chemistry - Unique superhalogen properties of Pt(CN)n complexes (n = 1–6) have been investigated under the quantum chemical formalism. The study involves theoretical calculations...     

Methyl 2-[(tert-Butoxycarbonyl)amino]-3-hydroxy-3-phenylpropanoate: Synthesis of Erythro (±) Isomer by Reduction and Threo (±) Isomer by Inversion Method

Russian Journal of General Chemistry - We report an efficient protocol for synthesis of methyl 2-[(tert-butoxycarbonyl) amino]-3-hydroxy-3-phenylpropanoate (Erythro (±)) by simple reduction...     

Analytical study for oblique wave interaction with a submerged horizontal perforated plate near a partially reflecting vertical wall

Meccanica - A novel iterative analytical solution is developed to study the oblique wave interaction with a horizontally submerged perforated plate near a partially reflecting vertical wall. The...