Article ID 0087 September 2019
Article ID 0088 September 2019
AMO4 ternary oxides are materials of fundamental and technological importance exhibiting a large variety of functional properties. Members of this family of compounds have multiple potential applications; for instance, as scintillators, thermophosphors, photocatalysts, and cathodoluminescence materials.Studies under high-pressure conditions are valuable for understanding the physical properties and phase behaviour of AMO4 oxides. In particular, great progress has been achieved in the last decade towards the understanding of the pressure-effects on the structural, vibrational, and electronic properties of AMO4 materials. Specifically, novel metastable structures with interesting physical properties have been discovered. In this article, a selection of recent results from high-pressure studies on different AMO4 oxides will be discussed, paying particular attention to orthovanadates. Remarkable phenomena like band-gap and volume collapses as well as phonon softening will be discussed and correlated with structural changes
Article ID 0089 September 2019
In the near future there would be a need for a high field MRI contrast agent for the MRI diagnostic due to the several disadvantages of Gd-based complexes, such as short circulation time and decrease in efficiency at high magnetic field i.e., greater than 3 T. The lanthanide-based nanoparticle can be an alternative to these complexes due to a high density of metal ions per unit of contrast agent. The high density of the metal ions will enable the MR signal shortening usually, at lower concentrations compared to chelates that typically are used at micro-molar concentrations. Additionally, the nanoparticles would retain their relaxivity efficiency at high magnetic field greater than 3 T
Article ID 0090 September 2019
Microneedle-based drug delivery has attracted researchers’ attention over the last decade. The material of construction of microneedles has emerged as a critical factor influencing clinical usage, manufacture, drug loading and drug stability. Initially, microneedles were fabricated using glass, silicon and metals. The development of sophisticated machining tools and advances in the polymer science allowed for a major shift in materials of construction of microneedles towards polymeric systems. Delivery of difficult to formulate therapeutics, including proteins, peptides, vaccines and genetic material has been established using microneedles. There is a constant search for newer materials, which can easily form microneedles with sufficient strength to penetrate biological barriers, can be easily manufactured, and are compatible with drug molecules and biological systems. While several reviews have discussed microneedle-based cosmetic and drug delivery applications, there is a gap in understanding the effect of material of construction of microneedles on drug stability and potential for large-scale manufacture. This review is an attempt to present microneedles as a function of the material used for its construction. Since microneedle commercialization is now a realistic possibility, we believe that improved understanding of materials and their chemistry will allow for improved decision making, especially for industries looking towards bringing microneedle technology to manufacturing setups.
Article ID 0091 September 2019
Drug delivery is a broad field which deals with the delivery of pharmaceutical compounds to the desired site with an aim to achieve maximum therapeutic effect and minimum toxicity in treating a diseased condition. To achieve the goal, a carrier system is required for controlled and sustained drug release. Polymers are an all-time favourite matrix used to control the release of drug at the desired rate. Among the polymers, the biopolymers derived from proteins are attracting considerable attention due to their utility in delivering vaccine and chemotherapeutics in clinical application. Additionally, they are biocompatible,biodegradable, and in certain cases, cost-effective. The review addresses the source, structure and characterization of different proteins used as drug delivery carriers. Along with this, the factors contributing to the release of drug from the protein carrier has also been discussed
Article ID 0092 September 2019
Among various fabrication techniques to produce a porous scaffold, thermally-induced phase separation at controlled cryogenic condition leads to the formation of a porous polymeric cryostructure alias cryogel or cryomatrix. Cryostructurization is one of the simple and versatile methods of synthesizing a highly porous and interconnected architecture. The process of cryostructurization is present in comparable fabrication approach of fabricating advanced porous biomaterials with precise control over multiple compositions of precursor units, spatial distributions for accomplishing effective recapitulation of mechanical properties and architectural accuracy at micron-scale with bioactive functionality. The cryogenically-structured polymeric scaffolds are of noteworthy fundamental and applied interest in multi-disciplinary areas of science and showed promising matrices in various biotechnological and biomedical areas. The large interconnected pores in cryogels open up a range of applications like the three-dimensional substrate for cell growth, bioreactor for continuous production of scarce molecules, bio-processing and protein purification, an adsorbent for environmental remediation, and biosensor fabrication. Over the past two decades, significant attention to these materials with rigorous expansion in their new designs, and remarkable growth in the number of the publications and patents on cryostructured porous materials has been noticed. This article is covering the progress in cryostructurization technology in the last few decades with principles underlying the mechanism of cryogelation, process optimization, and the recent trend in cryogel for biomedical and bioengineering applications.
Article ID 0093 October 2019
Highly crystalline, phase pure Cu3P nanocrystals (NCs) have been successfully synthesized using ionic liquid-assisted solvothermal method at relatively low temperature (200 ºC). Herein, ionic liquids (ILs) are used as a structure directing/templating agent. Effect of ILs and precursor concentration on crystal phase, crystallite size, lattice strain, morphology and grain size of Cu3P NCs is studied. In the presence of IL, crystallite size and lattice strain significantly change with changing the concentration of red phosphorus. For example, smaller crystallite size (38.5 nm) and compressive lattice strain are obtained when 10 times of red phosphorous is used. However, bigger size (41.9 nm) and tensile lattice strains are obtained for the lower concentration of phosphorous (5 times). At higher phosphorus concentration, hexagonal shaped microcrystals with prominent grain are observed. HRTEM images reveal that spherical-shaped particles on further agglomeration through Ostwald ripening process form hexagonal-shaped bigger microstructures. However, on doping the rare-earth ions (RE3+ = Ce3+/Tb3+) in the Cu3P NCs show the green luminescence (at 542 nm) which is attributed to the emission of Tb3+ ions. To the best of our knowledge, this is the first report on rare earthdoped Cu3P nanoparticles and shows promise on the luminescence aspect of Cu3P nanomaterials alongwith its already existing plasmonic and semiconducting properties.
Article ID 0094 September 2019
Acridone (acceptor) and naphthylamine (donor) based Donor-Acceptor-Donor (D-A-D) compound (1) was synthesised, characterised and its thermally-activated delayed fluorescence (TADF) properties were studied in detail. Compound 1 is fluorescent and emits in the green region (550 nm). The energy gapbetween the ground and the lowest excited singlet (S1) state is estimated to be 2.55 eV. The energy gap between the CT singlet and triplet states (ΔEST) was found to be ~0.3 eV. Small ΔES1-T1 is one of the important criteria for TADF to take place in a molecule and thus detailed photophysics has been studied.Transient lifetime measurements showed an increase in the fluorescence lifetime (s) on purging with N2, as compared with that in air-saturated solution, indicating the involvement of the triplet state in emission. Emission at 550 nm was also observed with a delay of 100 ls which corresponded to the delayed fluorescencein 1. The lifetime of TADF was found to be 176 ls. Applications of TADF materials in organic lightemitting devices (OLEDs) has gotten attention as TADF materials utilise the triplet excitons which helps in increasing internal quantum efficiency of device. Air-saturated based on 1 were fabricated and their intensity was found to be nearly as high as 17,000 Cd/m2 at 25 mA/cm2 which was comparable to many of the known TADF emitters.
Article ID 0095 September 2019
Concepts have been developed which favor low-energy absorption in the near-infrared (NIR) region. These include metal-metal charge transfer (inter-valence charge transfer) transitions of mixed-valent species, radical ion compounds (anions, cations), and mixtures thereof. Recent examples from ruthenium coordination chemistry are presented in order to illustrate analysis and assignment of such NIR transitions
Article ID 0096 September 2019
In this article, structural and magnetic properties of a number of A2MMnO6 (A = La, Eu and Y; M = Mg, Co, Ni) type perovskites prepared under different oxygen partial pressure are compared. The results indicated that both structure and magnetic properties of such materials are sensitive to preparation conditions,which in general is governed by the nature of transition metal ions as well as rare-earth ions. It was also pointed out that even though the deviation in structure is only marginal, they affect appreciably to their magnetic properties
Article ID 0097 September 2019
Materials play a key role in the safe and economical operation of nuclear reactors. Materials used in reactors also have to meet stringent chemical specifications for efficient performance. Commercial scale realization of nuclear materials has been a challenge to the nuclear industry. The history of development of nuclear materials has fascinating and unique examples of theoretical prowess as well as innovative experimentation and success in nuclear material development is characterized by synergy between the domains oflaboratory research and industry. This paper describes the development of some of the important nuclear materials (uranium, plutonium, zirconium, boron, sodium and graphite), providing a historical perspective
Article ID 0098 September 2019
This paper deals with hydrogen storage properties of Ti-V based BCC solid solution incorporated with Fe. The alloy with composition Ti2FeV was prepared by arc melting method. X-ray diffraction (XRD) and energy dispersive X-ray analysis studies confirmed formation of solid solution phase with uniform composition and BCC structure. SEM studies revealed the formation of irregular shaped particles with size in the range of few microns up on hydrogenation of the parent alloy. The alloy shows maximum hydrogen storage capacity of 3.41 wt.% at 20 bar and 303 K and the thermodynamic parameters established near roomtemperature suitability of the alloy for solid state hydrogen storage applications. Hydrogenation kinetics is found to be quite fast and detailed kinetic analysis were done to underscore the hydrogenation mechanism. Activation energy during the initial stage of hydrogenation is found to be 30.8 kJ/mol. The value decreases to14.4 kJ/mol for extended duration of hydrogenation, and this is explained based on difference in rate determining steps existing at different time scales
Article ID 0099 September 2019
Water splitting by Sulfur–Iodine (S–I) cycle is one of the promising thermochemical processes for hydrogen production due to its high efficiency. The decomposition of H2SO4 to produce SO2 is the reaction with the highest energy demand in the S–I cycle and it shows a large kinetic barrier. Sulfuric acid ishighly corrosive and its endothermic decomposition needs elevated temperatures (>800 ºC). Henceforth, before the scale-up of the process plant there is a need to explore various materials of construction under very harsh acidic environments and phase changing conditions. Corrosion studies on some of the possible materials of construction (SS-304, SS-310, SS-316, Inconel-800, Alloy-20, Inconel-600, Incoloy-800H, Hastelloy C-276) were performed in detail and the most corrosion resistant material is suggested for the construction of sulfuric acid decomposition unit. The studies were performed at low temperatures (60ºC and 120ºC) as well as at high temperatures (700ºC, 800ºC and 900ºC). The corrosion rates were determined using weight loss method at low as well as high temperature and by using electrochemical method at low temperature (80ºC). The phase changing condition was more severe and resulted in higher corrosion rate. Hastelloy C-276 showed the least corrosion rate.
Article ID 0100 September 2019
Molar heat capacities of two hydride ion conductors, namely, CaHCl and CaHBr, were measured by differential scanning calorimetry. The measured molar heat capacity data of these compounds as a function of temperature is given by the following expressions:Cp CaHCl (J K-1 mol-1) = 57.806 + 16.420 x 10-3. T - 1.006 x 106 .T-2 (308–748 K) Cp CaHBr (J K-1 mol-1) = 56.534 + 44.880 x 10-3.T - 1.481 x 106 .T-2 (323–713 K)
From the above expressions, molar enthalpy increments, entropies and Gibbs energy functions of these compounds were derived and reported.
Volume 131 | Issue 10
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