Polarization of emission spectra from Ti3+-doped oxide crystals

The Ti³⁺ ion in YAlO₃ (YAP), Y₃Al₅O₁₂ (YAG), and Al₂O₃ crystals occupies distorted octahedral sites relative to the nearest neighbour ligand ions. Such distortions are of even-parity in YAG where the zero-phonon lines in emission occur via magnetic dipole transitions. In contrast, the zero-phonon transitions occur by electric dipole processes in Ti³⁺:YAP and Ti³⁺:Al₂O₃ where there are odd-parity distortions from octahedral symmetry. This paper reports measurements of the zero-phonon lines of Ti³⁺ ions in YAP, YAG, and Al₂O₃ at 10 K. The zero-phonon lines of Ti³⁺:YAP are strongly polarized perpendicular to the tetragonal axis and those of Ti³⁺:Al₂O₃ parallel to the trigonal axis. The experimental results are shown to be in accord with a molecular orbital model of the radiative transition according to which the transition intensities derive from odd-parity ligand wavefunctions induced into even-parity ground and excited Ti³⁺ wavefunctions by odd-parity crystal distortions.     

Characterisation of Plasmodium falciparum aspartic protease inhibition by piperidine derivatives

Piperidine derivatives are reported to exhibit a variety of pharmacological activities. In this article, synthesis and aspartic protease inhibitory activity of three nitrophenacyl derivatives of N-methyl-4-hydroxy piperidine are reported. Enzyme assays showed that the attachment of a nitro group in the benzene ring plays an important role in the inhibition of plasmepsin-II of Plasmodium falciparum. The compound 1-methyl-1-(4'-nitrophenacyl)-4-hydroxypiperidinium bromide (3), consisting of a nitro group at the para position, was the most active at the concentration of 1.0?μM. The activity of the compounds was evaluated through the observed orientation and diagrammatic representation of nitrophenacyl derivatives of 4-hydroxy piperidine.     

Production of Biodegradable Polymer from Agro-Wastes in Alcaligenes sp. and Pseudomonas sp.

The present study was aimed to evaluate the suitability of agro-wastes and crude vegetable oils for the cost-effective production of poly-β-hydroxybutyrate (PHB), to evaluate growth kinetics and PHB production in Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 with these carbon substrates and to study the biodegradation of PHB accumulated by these cultures. Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 accumulates higher amounts of PHB corn (79.90% of dry cell mass) and rice straw (66.22% of dry cell mass) medium respectively. The kinetic model suggests that the Pseudomonas sp. RZS1 follows the Monod model more closely than A. faecalis RZS4. Both the cultures degrade their PHB extract under the influence of PHB depolymerase. Corn waste and rice straw appear as the best and cost-effective substrates for the sustainable production of PHB from Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1. The biopolymer accumulated by these organisms is biodegradable in nature. The agro-wastes and crude vegetable oils are good and low-cost sources of nutrients for the growth and production of PHB and other metabolites. Their use would lower the production cost of PHB and the low-cost production will reduce the sailing price of PHB-based products. This would promote the large-scale commercialization and popularization of PHB as an ecofriendly bioplastic/biopolymer.     

Electromagnetic Time Reversal Algorithms and Source Localization in Lossy Dielectric Media

The problem of reconstructing the spatial support of an extended radiating electric current source density in a lossy dielectric medium from transient boundary measurements of the electric fields is studied. A time reversal algorithm is proposed to localize a source density from loss-less wave-field measurements. Further, in order to recover source densities in a lossy medium, we first build attenuation operators thereby relating loss-less waves with lossy ones. Then based on asymptotic expansions of attenuation operators with respect to attenuation parameter, we propose two time reversal strategies for localization. The losses in electromagnetic wave propagation are incorporated using the Debye's complex permittivity, which is well-adopted for low frequencies (radio and microwave) associated with polarization in dielectrics.     

Room temperature deposition of ZnO and Al:ZnO ultrathin films on glass and PET substrates by DC sputtering technique

In the present work, ultrathin films of Zinc oxide (ZnO) and Aluminum doped zinc oxide (AZO) with 20 nm thick were fabricated at 300 K on glass and Polyethylene terephthalate (PET) substrates by means of direct-current sputtering method. The structural morphology of the films were analyzed by (XRD) diffractometry. The average transmittance of films deposited on different substrates showed high transparency (over 80%) in the visible spectrum. The objective of the present work is to investigate the thicknesses and optical constants of ZnO and AZO ultrathin films prepared by DC sputtering onto (glass and PET) substrates using two methods (UV–Vis–NIR spectrophotometer and ellipsometer (SE) by new amorphous dispersion formula) with comparison to check and confirm the results that obtained from UV with those obtained from SE measurements. The optical constants of films were extracted and compared using UV and SE techniques in the range of (200–2200 nm) with increment of 1 nm in order to confirm the accuracy of the UV and shown an excellent agreement.     

Graphene quantum dot–based electrochemical biosensing for early cancer detection

Electrochemical biosensing systems coupled with graphene quantum dots (GQDs) have demonstrated suitability for cancer diagnostic strategies, particularly to identify the changes facilitating the early phases of tumorigenesis as well as to detect ultralow concentrations of biomarkers that distinguish between normal and malignant cells. GQDs, known as a novel class of zero-dimensional semiconductor nanocrystals, are tiny graphene particles arranged in a honeycomb structure with a size range of 1–50 nm. The size of these GQDs is comparable with the size of biomolecules, thereby providing an ideal platform to study biomolecules such as proteins, cells, and viruses. GQDs are a superior platform for specific and sensitive recognition of cancer biomarkers; they are highly synergistic with electrochemical sensors. This review will shed light on the recent advancements made in the field of GQD-based electrochemical sensors for early cancer detection, with the aim of highlighting the prospects for further development in cancer diagnostics.     

Secondary Metabolite Profiling,Anti-Inflammatory and Hepatoprotective Activity of Neptunia triquetra (Vahl) Benth

The present study aimed to analyze the phytoconstituents of Neptunia triquetra (Vahl) Benth. Anti-inflammatory and hepatoprotective activities of ethanol (EE), chloroform (CE) and dichloromethane (DCME) of stem extracts were evaluated using in vivo experimental models. The extracts were analyzed for phytoconstituents using GC-HRMS. Anti-inflammatory activity of CE, EE and DCME was accessed using carrageenan-induced paw oedema, cotton pellet-induced granuloma and the carrageenan-induced air-pouch model in Wistar albino rats. The hepatotoxicity-induced animal models were investigated for the biochemical markers in serum (AST, ALT, ALP, GGT, total lipids and total protein) and liver (total protein, total lipids, GSH and wet liver weight). In the in vivo study, animals were divided into different groups (six in each group) for accessing the anti-inflammatory and hepatoprotective activity, respectively. GC-HRMS analysis revealed the presence of 102 compounds, among which 24 were active secondary metabolites. In vivo anti-inflammatory activity of stem extracts was found in the order: indomethacin > chloroform extract (CE) > dichloromethane extract (DCME) > ethanolic extract (EE), and hepatoprotective activity of stem extracts in the order: CE > silymarin > EE > DCME. The results indicate that N. triquetra stem has a higher hepatoprotective effect than silymarin, however the anti-inflammatory response was in accordance with or lower than indomethacin.