Probing the Nanoscale Heterogeneous Mixing in a High-Performance Polymer Blend

The blend of polyetheretherketone (PEEK) and polybenzimidazole (PBI) produces a high-performance blend (PPB) that is a potential replacement material in several industries due to its high temperature stability and desirable tribological properties. Understanding the nanoscale structure and interface of the two domains of the blend is critical for elucidating the origin of these desirable properties. Whilst achieving the physical characterisation of the domain structures is relatively uncomplicated, the elucidation of structures at the interface presents a significant experimental challenge. In this work, we combine atomic force microscopy (AFM) with an IR laser (AFM-IR) and thermal cantilever probes (nanoTA) to gain insights into the chemical heterogeneity and extent of mixing within the blend structure for the first time. The AFM-IR and nanoTA measurements show that domains in the blend are compositionally different from those of the pure PEEK and PBI polymers, with significant variations observed in a transition region several microns wide in proximity to domain boundary. This strongly points to physical mixing of the two components on a molecular scale at the interface. The versatility intrinsic to the combined methodology employed in this work provides nano- and microscale chemical information that can be used to understand the link between properties of different length scales across a wide range of materials.

Evaluation of in vitro Dissolution Profile and Physicochemical Characterization of Polymer Based Formulations of Sparingly Soluble Rosuvastatin

Rosuvastatin (RVT) is a BCS class II antilipidemic crystalline drug, which exhibits low bioavailability due to its very poor aqueous solubility; therefore, it is challenging to develop a proper formulation of RVT. To enhance solubility and bioavailability of this API, an attempt has been made by implementing solid dispersion technique. Solid dispersion (SD) technique is a solubility enhancing technique where one or more active entities are dispersed in an inert medium (matrix or carrier) at solid state. In this study, different ratios of Kollicoat® IR (KIR) and Kollidon® 90F (KF90) polymers were used with API to prepare various formulations by physical mixing (PM) and SD approaches; here solvent evaporation technique was used whereas methanol was used as solvent which was completely evaporated from the homogenously dispersed system by placing in a water-bath at 60-65°C and then in oven for 30 minutes at 50 °C. Among the formulations, RVT-KF90 SD formulations showed the most promising result in in-vitro study in terms of drug release profile (78.04 – 99.21%) in comparison to pure RVT (63.1%) and physical mixing of RVT with those polymers. USP dissolution apparatus type II was used at 37°C ± 0.5°C with 50 rpm to conduct the in-vitro experiment. The experiment also unraveled that the dissolution of RVT improved with increasing the amounts of polymers. Subsequently, stability of the developed formulations was conducted by Fourier transforms infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) as well as scanning electron microscopy (SEM). The results obtained from FTIR ensured no involvement of any significant drug-excipient interaction. Moreover, the DSC study signified thermal stability at high temperature. Besides, the SEM micrograph illustrated homogenous distribution of RVT in the polymer and transformation of crystal-like RVT into amorphous formulations. Dhaka Univ. J. Pharm. Sci. 20(2): 199-211, 2021 (December)

Study of Bandgap Energy of Novel Nanocomposite

In this novel work, we have studied the optical properties of CuBaM-CZFO nanocomposites. (Cu0.5Ba0.5Fe12O19)1-x/ (Co0.6Zn0.4 Fe2O4) x [where x=0.1,0.2] nanocomposites were synthesized individually by sol-gel citrate method and then made into nanocomposites by physical mixing technique. Further characterization over their structural, morphological and optical properties were carried out in detail. With the help of UV analysis, the optical properties such as, the band gap energy was discovered which is found using Tauc’s plot. The bandgap energy is 2.6503eV for CuBaM-CZFO 90-10 which is lesser than CuBaM-CZFO 80-20 (2.8456eV). The structural, morphological and optical properties of novel CuBaM-CZFO nanocomposite are reported and compared with, both among themselves and from the literature review.

On the Resolution of Compositional Datasets into Convex Combinations of Extreme Vectors

<p>Large compositional datasets of the kind assembled in the geosciences are often of remarkably low approximate rank. That is, within a tolerable error, data points representing the rows of such an array can approximately be located in a relatively small dimensional subspace of the row space. A physical mixing process which would account for this phenomenon implies that each observation vector of an array can be estimated by a convex combination of a small number of fixed source or 'endmember' vectors. In practice, neither the compositions of the endmembers nor the coefficients of the convex combinations are known. Traditional methods for attempting to estimate some or all of these quantities have included Q-mode 'factor' analysis and linear programming. In general, neither method is successful. Some of the more important mathematical properties of a convex representation of compositional data are examined in this thesis as well as the background to the development of algorithms for assessing the number of endmembers statistically, locating endmembers and partitioning geological samples into specified endmembers. Keywords and Phrases: Compositional data, convex sets, endmembers, partitioning by least squares, iteration, logratios.</p>

On the Resolution of Compositional Datasets into Convex Combinations of Extreme Vectors

<p>Large compositional datasets of the kind assembled in the geosciences are often of remarkably low approximate rank. That is, within a tolerable error, data points representing the rows of such an array can approximately be located in a relatively small dimensional subspace of the row space. A physical mixing process which would account for this phenomenon implies that each observation vector of an array can be estimated by a convex combination of a small number of fixed source or 'endmember' vectors. In practice, neither the compositions of the endmembers nor the coefficients of the convex combinations are known. Traditional methods for attempting to estimate some or all of these quantities have included Q-mode 'factor' analysis and linear programming. In general, neither method is successful. Some of the more important mathematical properties of a convex representation of compositional data are examined in this thesis as well as the background to the development of algorithms for assessing the number of endmembers statistically, locating endmembers and partitioning geological samples into specified endmembers. Keywords and Phrases: Compositional data, convex sets, endmembers, partitioning by least squares, iteration, logratios.</p>

Silver Abietate and β-Cyclodextrin Inclusion Complex Doped Poly(vinyl alcohol) Nanowebs

In this study, guesthost inclusion complexes of silver abietate with β-cyclodextrin were prepared by kneading and physical mixing techniques, and analyzed via fourier transformed infrared spectroscopy (FTIR) and thermogravimetric analyser (TGA). The 1:1 and 1:2 stoichiometry of the guesthost were prepared. Obtained FTIR and TGA results showed that formation of silver abietate:β-cyclodextrin (Ag-A:β-CD) inclusion complexes occurred at a mass ratio of both 1:1 and 1:2. Furthermore, prepared Ag-A:β-CD (1:2) inclusion complex was doped in Poly(vinyl alcohol) nanofibers during electrospinning process for obtaining nanowebs. The formation of nanowebs were investigated under scanning electron microscope (SEM), X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR) and thermogravimetric analyser (TGA). The results confirmed Ag-A:β-CD inclusion complex containing Poly(vinyl alcohol) (PVA) nanoweb production.

COPROCESSED EXCIPIENTS-PREPARATION AND FUNCTIONALITIES

With the advancements of tablet manufacturing techniques, the urge to develop and produce high, multifunctional excipients have been increased to meet the set of functionalities. The functionality of the coprocessed excipients enhances the manufacturing process and as well improves quality,performance of tablets.Coprocessed excipients are defined as the mixture of two or more than two excipients that possess specific potential advantages which cannot be produced by simple physical mixing of same combination of excipients.The aim of this review is to focus on advantages, preparation methods of coprocessed excipients. Coprocessing is a technique, where these compendial or non compendial excipients are modified physically in a special way without changing their chemical structure.This review article discusses the need for developing coprocessed excipients, advantages of coprocessed excipients, different methods of preparation of coprocessed excipients and functionalities of coprocessed excipients

In Situ Hydroxyapatite Synthesis Enhances Biocompatibility of PVA/HA Hydrogels

Bone tissue engineering tries to simulate natural behavior of hard tissues. This study aimed to produce scaffolds based on polyvinyl alcohol (PVA) and hyaluronic acid (HA) with hydroxyapatite (HAp) incorporated in two different ways, by in situ synthesis and physical mixing of pre-prepared HAp. In situ synthesis resulted in calcium deficient form of HAp with lower crystallinity. The proliferation of human osteoblast-like cells MG-63 proved to be better in the scaffolds with in situ synthesized HAp compared to those with physically mixed pre-prepared HAp. For scaffolds with PVA/HA/HAp ratio 3:1:2, there was significantly higher initial adhesion (p = 0.0440), as well as the proliferation in the following days (p < 0.001). It seemed to be advantageous improve the properties of the scaffold by in situ synthesizing of HAp directly in the organic matrix.

Exothermic behaviour of aluminium and graphene as a fuel in Fe2O3 based nanothermite

The main frontier of this research is to study the influence of multi-layer graphene (MLG) and aluminium as a fuel in Al/Fe2O3 and MLG/Fe2O3 nanothermites, fabricated by physical mixing and ultrasonication techniques. To study the structural and energy release properties, prepared samples were characterized by XRD, FESEM, EDS, FTIR, Raman spectroscopy and DSC. The X-ray diffraction (XRD) technique showed that all the phases remain intact during the synthesis. Field emission electron microscopy (FESEM) micrographs displayed the surface morphology of the samples, and besides this, energy dispersive spectroscopy (EDS) was used to check the elemental composition of samples. Raman spectroscopy revealed that the ultrasonication waves did not deteriorate the aromatic structure of graphene sheets. Fourier transform infrared spectroscopy (FTIR) spectra were used to observe the information about various functional groups present in the thermite samples. The exothermic energy released by the thermite reaction in both the samples was investigated by differential scanning calorimetry (DSC) and the observed values of energy release for Al/Fe2O3 and MLG/Fe2O3 are 215 J/g and 1640 J/g.