Second-Order Duality in Multiobjective Programming Involving (F, α, ρ, d)-V-Type I Functions

In this paper, a new class of second-order (F, α, ρ, d)-V-type I functions is introduced that generalizes the notion of (F, α, ρ, θ)-V-convex functions introduced by Zalmai (Computers Math. Appl. 2002; 43:1489–1520) and (F, α, ρ, p, d)-type I functions defined by Hachimi and Aghezzaf (Numer. Funct. Anal. Optim. 2004; 25:725–736). Based on these functions, weak, strong, and strict converse duality theorems are derived for Wolfe and Mond–Weir type multiobjective dual programs in order to relate the efficient and weak efficient solutions of primal and dual problems.     

Kinetics and mechanism of electron transfer reactions in aqueous solutions: Silver(I) catalyzed oxidation of aspartic acid by cerium (IV) in acid perchlorate medium

Silver(I) catalyzed oxidation of aspartic acid by cerium(IV) was studied in acid perchlorate medium. The stoichiometry of the reaction is represented by the eq. (i) Dimeric cerium(IV) species has been indicated and employed in calculations of monomeric cerium(IV) species concentrations. The reaction is second-order and uncatalyzed reaction also simultaneously occurs along with the silver(I) catalyzed reaction conforming to the rate law (ii) where k is an observed second-order rate constant. A probable reaction mechanism is suggested. © 1995 John Wiley & Sons, Inc.     

Mononuclear, dinuclear, and pentanuclear [[N,S(thiolate)]iron(II)] complexes: nuclearity control, incorporation of hydroxide bridging ligands, and magnetic behavior

The mixed N3S(thiolate) ligand 1-[bis[2-(pyridin-2-yl)ethyl]amino]-2-methylpropane-2-thiol (Py2SH) was used in the synthesis of four iron(II) complexes: [(Py2S)FeCl] (1), [(Py2S)FeBr] (2), [(Py2S)4Fe5II(mu-OH)2](BF4)4 (3), and [(Py2S)2Fe2II(mu-OH)]BF4 (4). The X-ray structures of 1 and 2 revealed monomeric iron(II)-alkylthiolate complexes with distorted trigonal-bipyramidal geometries. The paramagnetic 1H NMR spectra of 1 and 2 display resonances from delta = -25 ppm to +100 ppm, consistent with a high-spin iron(II) ion (S = 2). Spectral assignments were made on the basis of chemical shift information and T1 measurements and show the monomeric structures are intact in solution. To provide entry into hydroxide-containing complexes, a novel synthetic method was developed involving strict aprotic conditions and limiting amounts of H2O. Reaction of Py2SH with NaH and Fe(BF4)2.6 H2O under aprotic conditions led to the isolation of the pentanuclear, mu-OH complex 3, which has a novel dimer-of-dimers type structure connected by a central iron atom. Conductivity data on 3 show this structure is retained in CH2Cl2. Rational modification of the ligand-to-metal ratio allows control over the nuclearity of the product, yielding the dinuclear complex 4. The X-ray structure of 4 reveals an unprecedented face-sharing, biooctahedral complex with an [S2O] bridging arrangement. The magnetic properties of 3 and 4 in the range 1.9-300 K were successfully modeled. Dinuclear 4 is antiferromagnetically coupled [J = -18.8(2) cm(-1)]. Pentanuclear 3 exhibits ferrimagnetic behavior, with a high-spin ground state of S(T) = 6, and was best modeled with three different exchange parameters [J = -15.3(2), J' = -24.7(3), and J' = -5.36(7) cm(-1)]. DFT calculations provided good support for the interpretation of the magnetic properties.     

Formulation performance window for manufacturing cellulose-based sustained-release mini-matrices of highly water-soluble drug via hot-melt extrusion technology

The aim of the proposed work was to develop robust hot-melt extrusion (HME) process for fabricating sustained-release mini-matrices (pellets) of a highly water-soluble drug, tramadol hydrochloride. The current work was designed to identify a formulation window with target functional performances such as streamlined processability and sustained-release profile with alcohol-resistant properties. HME was used to perform screening tests of various drug loadings and excipients to determine the acceptable limit of each independent component (critical material attributes, CMAs) in the Design of Experiment (DoE). It was observed that the ratio of hydrophobic (ethyl cellulose, EC; Compritol^® ATO 888, C888) to hydrophilic (hydroxypropyl cellulose, HPC) components were critical factors evaluated using DoE. The processing temperature (105–175 °C) was identified as a critical process parameter. FTIR chemical imaging was used to assess the drug-matrix interaction, confirming a homogeneous drug distribution inside the polymer-lipid matrix system. SEM analysis and FTIR results were also in close agreement. Finally, a feasible formulation window containing EC, C888, and HPC in the ratios of 40:20:10 with the desired quality target product profile was successfully developed. Hydroalcoholic dissolution studies revealed safe and sustained-release of tramadol that resisted drug release variations for the first few hours in alcohol. The developed mini-matrices followed the Peppas–Sahlin model indicating a combination of Fickian diffusion and swelling mechanisms. Herein we conclude, a successful blueprint technology for the development of alcohol-resistant mini-matrices of tramadol hydrochloride via HME to provide once-a-day therapy for pain management, consequently reducing the dosing frequency.

Graphical abstract

     

Relative controllability of nonlinear neutral fractional integro‐differential systems with distributed delays in control

In this paper, we establish sufficient conditions for the global relative controllability of nonlinear neutral fractional Volterra integro‐differential systems with distributed delays in control. The results are obtained by using the Mittag–Leffler functions and the Schauder fixed‐point theorem. Examples are presented to illustrate the results. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthetic pharmaceutical peptides characterization by chromatography principles and method development

As per the United States Food and Drug Administration, any polymer/chain composed of 40 or fewer amino acids is called a peptide, where more than 40 amino acids are considered proteins. On many occasions, there is a change in the source of manufacturing of the peptide active pharmaceutical ingredient, where one has to prove the sameness of that product with the existing formulation by considering several aspects like the presence of impurities/degradation products, the extent of aggregations, and so forth. For the same, several chromatographic characterization techniques such as reversed-phase high-performance liquid chromatography-ultraviolet/high-resolution mass spectrometry, supercritical fluid chromatography, size-exclusion chromatography, ion-exchange chromatography, and so forth, are widely used in the pharmaceutical industry. It is well known that the method development of peptide molecules is often challenging as many variables are to be kept in mind which can affect the separation, recovery, and stability of the molecule. The present review focuses on the basics of peptide degradation and method development by using various chromatographic techniques for characterization. It also covers a deep insight of method development parameters and variables to be considered which might directly or indirectly affect the chromatographic separation and recovery and also provides a guide on the selection of chromatographic parameters.     

Silica sulfuric acid mediated synthesis of naphtho[2,1-b]furan derivatives and development of one-pot multicomponent synthesis of substituted pyrazole derivatives

Silica sulfuric acid (SSA) mediated synthesis of naphtho[2,1-b]furan derivatives starting from β-nitrostyrene derivatives and β-naphthol derivatives under solvent-free conditions have been developed. The scope of SSA as a heterogeneous catalyst is extended to one-pot multicomponent reaction for the synthesis of functionalized pyrazole derivatives under solvent-free conditions from readily available β-nitrostyrene derivatives, acetyl acetone, and hydrazine hydrate. The synthetic methods have significant advantages such as solvent-free conditions, simple operation, shorter reaction times, ease and clean isolation procedures, and very good yields of products.     

Biosurfactants—An Overview

The large structural and functional variety of bio-surfactants (BS), which are produced by microorganisms, leads to the use of several methods to study these amphiphilic molecules. This review seeks to consolidate information on various surface-active product extraction techniques, microbiological screening methodologies, and analytical terminologies utilized in this sector. The potential benefits and drawbacks of various approaches for studying cell biomass or microbial culture broth for the generation of surface-reactive chemicals are also discussed. Additionally, the most popular techniques for detection, structural characterization, and purification of a variety of BS are introduced. A number of straightforward techniques are described in detail, including dialysis, ion exchange, solvent extraction, ultrafiltration, lyophilization, and thin layer chromatography (TLC). In addition to more sophisticated techniques like nuclear magnetic resonance (NMR), fast atom bombardment mass spectroscopy (FAB-MS), gas chromatography-mass spectroscopy (GC-MS), high-pressure liquid chromatography (HPLC), and infrared (IR), proteolysis and sequencing of amino acid are also explained. In this field of study, it is quite necessary to combine several analytical techniques, and it often takes multiple iterations to purify, isolate, and characterize different surface-active substances. The numerous approaches that are essential for researching bio-surfactants are covered in this review.     

Novel Synthesis and Characterization of Irbesartan Derivative an Anti-Hypertensive Active Pharmaceutical Ingredient (API)

The current research focuses on the design, method development, characterization, and clinical assessment of novel irbesartan medication compounds. The objective of synthetic modification of a drug molecule is to achieve the desired properties such as enhancing the pharmacological properties and minimizing the side effects. It is a biphenyl tetrazole and an aza-spiro compound, a highly selective, potent nonpeptide compound that belongs to the sartan group, an authorized type-1 angiotensin II receptor (AT1), dilates the blood vessels and is used in curing of to treat high blood pressure, cardiac arrest, and renal disease in diabetics. To achieve the structural modification of the irbesartan drug, the researcher prepared the FeCl₃/SiO₂ catalyst and successfully used it for the acetylation, chloro acetylation reaction of irbesartan with acetyl chloride and chloroacetyl chloride. Further, the reaction is performed in presence of the catalyst and without a catalyst to elucidate the role of the catalyst. With the aid of TLC, FT-IR, and UV–visible spectral methods, the structural interpretation of synthesized derivatives is completed. The present work illustrates a novel method of synthesis of irbesartan derivatives through safe and convenient procedures. The pharmacological evaluation of synthetic derivatives and green chemistry protocol of synthesis is under progress.