Dynamic correlation effects on drag resistivity of a symmetric electron–electron bilayer

We have studied the effect of dynamic electron correlations on Coulomb drag in a low density symmetric electron–electron bilayer. The drag resistivity is calculated considering the contribution from direct e–e scattering processes using the semi-classical Boltzmann approach, with the effective inter-layer interaction W₁₂(q, ω; T) determined within the ?wierkowski, Szyman?ki, and Gortel model, generalized to include the dynamics of electron correlations through the frequency-dependent intra- and inter-layer local-field correction (LFC) factors. In turn, the LFCs are obtained by extending the quantum Singwi, Tosi, Land, and Sjölander (qSTLS) approach to finite temperatures. At low temperatures (T ? 2 K), the calculated drag resistivity is found to agree nicely with the measurements by Kellogg et al., while it is somewhat overestimated at higher temperatures. The overestimation is seen to increase with decreasing density of electrons. However, there is found to be a marked improvement over the predictions of the conventional (i.e., static) STLS and random-phase approximation (RPA). It turns out that the inclusion of exchange-correlations in the RPA causes a red-shift in the bilayer plasmons which leads to an enhancement of drag resistivity. Our study demonstrates clearly the importance of including the dynamical nature of correlations to have a reasonable account of measured drag resistivity.     

Supersaturation-Based Drug Delivery Systems: Strategy for Bioavailability Enhancement of Poorly Water-Soluble Drugs

At present, the majority of APIs synthesized today remain challenging tasks for formulation development. Many technologies are being utilized or explored for enhancing solubility, such as chemical modification, novel drug delivery systems (microemulsions, nanoparticles, liposomes, etc.), salt formation, and many more. One promising avenue attaining attention presently is supersaturated drug delivery systems. When exposed to gastrointestinal fluids, drug concentration exceeds equilibrium solubility and a supersaturation state is maintained long enough to be absorbed, enhancing bioavailability. In this review, the latest developments in supersaturated drug delivery systems are addressed in depth.     

Involvement of Phytochemical-Encapsulated Nanoparticles’ Interaction with Cellular Signalling in the Amelioration of Benign and Malignant Brain Tumours

Brain tumours have unresolved challenges that include delay prognosis and lower patient survival rate. The increased understanding of the molecular pathways underlying cancer progression has aided in developing various anticancer medications. Brain cancer is the most malignant and invasive type of cancer, with several subtypes. According to the WHO, they are classified as ependymal tumours, chordomas, gangliocytomas, medulloblastomas, oligodendroglial tumours, diffuse astrocytomas, and other astrocytic tumours on the basis of their heterogeneity and molecular mechanisms. The present study is based on the most recent research trends, emphasising glioblastoma cells classified as astrocytoma. Brain cancer treatment is hindered by the failure of drugs to cross the blood–brain barrier (BBB), which is highly impregnableto foreign molecule entry. Moreover, currently available medications frequently fail to cross the BBB, whereas chemotherapy and radiotherapy are too expensive to be afforded by an average incomeperson and have many associated side effects. When compared to our current understanding of molecularly targeted chemotherapeutic agents, it appears that investigating the efficacy of specific phytochemicals in cancer treatment may be beneficial. Plants and their derivatives are game changers because they are efficacious, affordable, environmentally friendly, faster, and less toxic for the treatment of benign and malignant tumours. Over the past few years, nanotechnology has made a steady progress in diagnosing and treating cancers, particularly brain tumours. This article discusses the effects of phytochemicals encapsulated in nanoparticles on molecular targets in brain tumours, along with their limitations and potential challenges.     

Study of Raman spectrum of uranium using a surface‐enhanced Raman scattering technique

Raman spectroscopic investigation on weak scatterers such as metals is a challenging scientific problem. Technologically important actinide metals such as uranium and plutonium have not been investigated using Raman spectroscopy possibly due to poor signal intensities. We report the first Raman spectrum of uranium metal using a surface‐enhanced Raman scattering‐like geometry where a thin gold overlayer is deposited on uranium. Raman spectra are detected from the pits and scratches on the sample and not from the smooth polished surface. The 514.5‐ and 785‐nm laser excitations resulted in the Raman spectra of uranium metal whereas 325‐nm excitation did not give rise to such spectra. Temperature dependence of the B_3g mode at 126 cm⁻¹ is also investigated. Copyright © 2011 John Wiley & Sons, Ltd.     

Defect characterization of mixed SrCa tartrates

A few defect characteristics which are typical of gel-grown mixed single crystals of SrCa tartrates (Sr_1−XCa_xC₄H₄O₆ · 4H₂O) having different concentration, x, of the cations have been described. The temperature of decomposition has been found to be related, to some extent, to dislocation concentration. The magnitude of configurational entropy, which is a manifestation of lattice disorder, has been computed. The Vickers microhardness and dislocation density of crystals have been found to bear good correlation. An empirical formula has been suggested to explain the observed variation in microhardness with the concentration of ions in the mixed lattice.     

Growth and characterization of mixed Sr: Ca tartrates

Single crystals of Sr_1−xCa_xC₄H₄O₆ · 4 H₂O of different compositions and forms were grown by controlled diffusion of ions through suitable silica gels and characterized. Pycnometer density, lattice parameter, dislocation density, dissolution, cleavage, etc. are some of the interesting features which distinguish mixed crystals from the pure ones.