Understanding stability relationships among three curcumin polymorphs

Understanding thermodynamic stability relationship among polymorphs of any active pharmaceutical ingredient (API) is a necessary step for drug formulation development. Knowledge of such relationship enables identification of a stable polymorphic form at the prevalent conditions. Curcumin, a pharmaceutically active ingredient found in herbal spice turmeric, exists in three polymorphic forms; a monoclinic form (Form 1) and two orthorhombic forms (Form 2 and Form 3). However, thermodynamic stability relationships among curcumin polymorphs have not been ascertained yet. This work therefore, was focused on understanding thermodynamic stability relationships among curcumin polymorphs. During purification of curcumin, the pressure applied for vacuum evaporation of organic solvent was found to significantly affect the polymorphic outcome. Form 1 was obtained at pressures ranging from 300 to 400?mbar whereas Form 2 was obtained at pressures ranging from 100 to 200?mbar. Form 3 was obtained by liquid antisolvent precipitation using ultrasound and Bovine Serum Albumin (BSA) as an additive. The obtained polymorphs were characterized by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC) techniques. Relative stability of polymorphs was established by conducting solvent mediated transformation studies, thermal analysis through DSC and variable temperature X-ray diffraction studies (VT-XRD). It was observed that Form 2 and Form 3 irreversibly convert to Form 1 upon heating. Further, Form 2 and Form 3 convert to Form 1 in aqueous organic solutions at temperatures ranging from 0?°C to 50?°C. Thus, the curcumin polymorphs were found to be monotropically related to each other with the monoclinic form (Form 1) being the most stable form.     

Humidity sensing properties of spray deposited Fe doped TiO2 thin film

In the present work,ferrite (Fe) doped TiO2 thin films with different volume percentage (vol％) were synthesized us-ing a spray pyrolysis technique.The effect of Fe doping on structural properties such as crystallite size,texture coefficient,mi-crostrain,dislocation densities etc.were evaluated from the X ray diffratometry (XRD) data.XRD data revealed a polycrystalline anatase TiO2 phase for sample synthesized up to 2 vol％ and mixed anatase and rutile crystalline phase for sample synthesized at 4 vol％ Fe doped TiO2.The crystalline size was observed to decrease with increase in Fe dopant vol％ and also other structur-al parameters changes with Fe dopant percentage.In the present work,electrical resistance was observed to decrease with a rise in Fe dopant vol％ and temperature of the sample.Thermal properties like temperature coefficient of resistance and activa-tion energy also showed strong correlation with Fe dopant vol％.Humidity sensing properties of the synthesized sample altered with a change in Fe dopant vol％.In the present paper,maximum sensitivity of about 88.7％ for the sample synthes-ized with 2 vol％ Fe doped TiO2 and also the lowest response and recovery time of about 52 and 3 s were reported for the same sample.     

Shape memory properties and unusual optical behaviour of an interpenetrating network of poly(ethylene oxide) and poly(2‐hydroxyethyl methacrylate)

An interpenetrating polymer network (IPN) with shape memory properties was prepared by using poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(ethylene oxide) (PEO). PHEMA acts as a fixed phase and PEO as a switching phase. The switching action of PEO is due to the reversible process of melting and crystallization. It was observed that the shape recovery of the IPN increases with increasing crosslinker concentration up to an optimum value and decreases thereafter. In addition to the shape memory property, the IPNs show a reversible change in optical properties from translucent to opaque. The change in optical properties is quite different from that observed in a semicrystalline polymer system where the transparency increases as a result of the melting of crystals. This behaviour of the IPN is explained in terms of H‐bonding of PEO with PHEMA. Fourier transform infrared spectroscopy was used to study the H‐bonding between PEO and PHEMA. © 2019 Society of Chemical Industry     

Cover Image,Volume 68, Issue 4

The cover image is based on the Research Article Enhancement of orientation of rigid polymer blocks by incorporating rod‐coil block copolymer chains into metal‐organic frameworks by Jin Wang et al. DOI: 10.1002/pi.5766 .

     

Assembly of phase transferred nickel nanoparticles at air-water interface using Langmuir-Blodgett technique

Development of simple and efficient protocol for the synthesis of Ni nanoparticles in aqueous media and their subsequent phase transfer to organic media is reported. The synthesis of nickel nanoparticles in aqueous medium is accomplished by reducing the nickel nitrate with sodium borohydride in presence of oleic acid. It results in the formation of nickel nanoparticles capped with oleic acid. The pristine oleic acid capped nickel nanoparticles were then phase transferred to nonpolar solvents such as toluene using stearic acid. The phase transfer was effective probably due to the space exchange between the oleic acid moiety and stearic acid molecules. The hydrophobized Ni thus obtained was organized at the air-water interface and it was observed that by controlling the pressure and concentration of hydrophobized Ni nanoparticles at air-water interface, linear ribbon like assemblies could be obtained. The organization process was followed by surface pressure-area isotherm measurement and Brewster Angle Microscopy.     

Interpenetrating polymer networks based on carboxylated nitrile rubber and poly(alkyl methacrylate)s

A series of interpenetrating polymer networks (IPNs) based on carboxylated nitrile rubber (XNBR) and poly(alkyl methacrylate)s such as poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA) and poly(butyl methacrylate) (PBuMA) were synthesized. The compositions of the IPNs were also varied by changing the swelling time of the rubber in the methacrylate monomer. The tensile and dynamic mechanical properties of the IPNs were studied. The dynamic mechanical properties in the range of 1–10⁵ Hz were obtained by the time‐temperature superposition of the data under multifrequency mode, which indicated high tanδ with good storage modulus in the entire frequency range. This indicates the suitability of these IPNs as vibration and acoustic dampers.     

GABAergic influences on plus-maze behaviour in mice

Manipulations of GABA function have been found to produce highly variable effects in animal models of anxiety. In the present series, an ethological version of the murine elevated plus-maze was used to examine in detail the behavioural profiles of diazepam (1.5 mg/kg; positive control) and a range of GABA-related compounds: valproic acid (100-400 mg/kg), No-711 (1.25-10.0 mg/kg), muscimol (0.5-3.0 mg/kg), (+)bicuculline (4.0-8.0 mg/kg), picrotoxin (0.25-2.0 mg/kg), R(+)baclofen (0.375-3.0 mg/kg) and CGP 35348 (25-200 mg/kg). On both conventional and ethological indices, results confirmed the anxiolytic profile of diazepam under present test conditions, and revealed substantially similar effects for the GABA-T inhibitor, valproic acid (100-400 mg/kg), and the GABAA receptor agonist, muscimol (2 mg/kg). The GABA reuptake inhibitor, No-711, produced weak anxiolytic-like effects at low doses (1.25-2.5 mg/kg) but disrupted behaviour at the highest dose tested (10 mg/ kg). Although the GABAA receptor antagonists, (+)bicuculline and picrotoxin, produced changes indicative of anxiety enhancement, concomitant behavioural suppression was evident at high doses (8 mg/kg and 1-2 mg/kg, respectively). Further studies suggested that the effects observed with bicuculline may be mediated by an active metabolite, such as bicucine. In contrast to the effects of valproic acid and direct GABAA receptor manipulations, the GABAB receptor agonist, R(+) baclofen, non-specifically disrupted behaviour at the highest dose tested (3 mg/kg) while the GABAB receptor antagonist, CGP 35348, was inactive over the dose range studied. Although present data confirm the sensitivity of the plus-maze to agents which modify GABAA receptor function, further studies will be required in order more fully to characterize this relationship.     

Efficient query evaluation on probabilistic databases

We describe a framework for supporting arbitrarily complex SQL queries with “uncertain” predicates. The query semantics is based on a probabilistic model and the results are ranked, much like in Information Retrieval. Our main focus is query evaluation. We describe an optimization algorithm that can compute efficiently most queries. We show, however, that the data complexity of some queries is #P-complete, which implies that these queries do not admit any efficient evaluation methods. For these queries we describe both an approximation algorithm and a Monte-Carlo simulation algorithm.     

The Membrane Proteome of Spores and Vegetative Cells of the Food-Borne Pathogen Bacillus cereus

Membrane proteins are fascinating since they play an important role in diverse cellular functions and constitute many drug targets. Membrane proteins are challenging to analyze. The spore, the most resistant form of known life, harbors a compressed inner membrane. This membrane acts not only as a barrier for undesired molecules but also as a scaffold for proteins involved in signal transduction and the transport of metabolites during spore germination and subsequent vegetative growth. In this study, we adapted a membrane enrichment method to study the membrane proteome of spores and cells of the food-borne pathogen Bacillus cereus using quantitative proteomics. Using bioinformatics filtering we identify and quantify 498 vegetative cell membrane proteins and 244 spore inner membrane proteins. Comparison of vegetative and spore membrane proteins showed there were 54 spore membrane-specific and 308 cell membrane-specific proteins. Functional characterization of these proteins showed that the cell membrane proteome has a far larger number of transporters, receptors and proteins related to cell division and motility. This was also reflected in the much higher expression level of many of these proteins in the cellular membrane for those proteins that were in common with the spore inner membrane. The spore inner membrane had specific expression of several germinant receptors and spore-specific proteins, but also seemed to show a preference towards the use of simple carbohydrates like glucose and fructose owing to only expressing transporters for these. These results show the differences in membrane proteome composition and show us the specific proteins necessary in the inner membrane of a dormant spore of this toxigenic spore-forming bacterium to survive adverse conditions.     

Comparison of temperature rise within pulp chamber during light curing of composite restoration

In this study, total of 60 extracted human teeth were divided into four groups. Group I and II were subjected to LCU A (2550 mW/cm²) and Group III and IV to LCU B (700 mW/cm²), respectively. The increase in temperature level from baseline was recorded using K type thermocouple while curing of dentin bonding agent and composite resins. The temperature rise was significantly higher for Light Curing Unit A which had higher intensity light than Light Curing Unit B. Remaining dentin thickness of the prepared tooth also has significant role in the temperature rise. Hence, light curing units should be used with caution to avoid over-exposure of teeth. Dental practitioners need to prepare teeth with silicone indices and pre-assessment of radiographs to avoid over-preparation. Regular check of intensity of light curing unit using commercially available intensity meter is advocated.