Separate Einstein‐Eddington spaces and the cosmological constant

Based on Eddington affine variational principle on a locally product manifold, we derive the separate Einstein space described by its Ricci tensor. The derived field equations split into two field equations of motion that describe two maximally symmetric spaces with two cosmological constants. We argue that the invariance of the bi‐field equations under projections on the separate spaces, may render one of the cosmological constants to zero. We also formulate the model in the presence of a scalar field. The resulted separate Einstein‐Eddington spaces maybe considered as two states that describe the universe before and after inflation. A possibly interesting affine action for a general perfect fluid is also proposed. It turns out that the condition which leads to zero cosmological constant in the vacuum case, eliminates here the effects of the gravitational mass density of the perfect fluid, and the dynamic of the universe in its final state is governed by only the inertial mass density of the fluid.

     

Synthesis of derivatives of pyrido-[1,2-<Emphasis Type="Italic">c</Emphasis>][1,3,2]oxazaborinine and pyrido-[2,1,6-<Emphasis Type="Italic">f,g</Emphasis>][1,3,7,2]dioxazaphosphacyclo-decane

The condensation of 2,6-di(o-hydroxyphenyl)-3,5-diphenyl-γ-piperidone with boric and boronic acids gave a series of 1,3,4,11b-tetrahydro-2H-benzo[e]pyrido[1,2-c][1,3,2]oxazaborinin-2-ones. The action of phosphorus oxytrichloride on this piperidone gave a derivative of 8,10-dioxa-21-aza-9-phospha-pentacyclohenicosahexaene. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1882–1886, December, 2008.     

Total annual effective dose and health risk due to intake of natural radionuclides of some vegetables cultivated in suburban Ho Chi Minh City,Vietnam

Journal of Radioanalytical and Nuclear Chemistry - In this work, activity concentration of 40K, 226Ra, 232Th, gross alpha and gross beta and annual effective dose due to ingestion of natural...     

A linear energy relationship between activation energy and absolute hardness: a case study with the O(3P) atom-addition reactions to polyaromatic hydrocarbons

A new linear relationship between absolute hardness and global activation energy of O-addition reaction to a series of aromatic hydrocarbons (benzene, naphthalene, phenanthrene, and pyrene) is presented. A total of seventeen O((3)P)-addition reactions were evaluated. Thermal rate constants were calculated for each elementary reaction and used to estimate the total rate constants. This information was employed to obtain the global activation energy. A new linear relationship is shown and is estimated that it can be used within the RC-TST framework to predict relative rate constants for any reaction within an O-addition to PAH class from just absolute hardness values.     

Dynamic operation of liquid crystal cell with inherently nanogroove-featured aligned carbon nanotube sheets

The use of a highly aligned carbon nanotube (CNT) sheet as a multifunctional constituent for liquid crystal (LC) displays and electro-optic LC applications is assessed. The CNT sheet can perform a dual function: one is an alignment layer for LCs, replacing the commonly used rubbed polyimide film, and the other is a transparent conductive layer, taking the place of indium tin oxide. The hydrophobic treatment improved the adhesion quality between aligned CNT bundles and the glass substrate, which helps to preserve the inherently aligned nanogroove morphology of transparent CNT sheets. The test LC display cells, comprising 4-cyano-4′-pentylbiphenyl molecules sandwiched between CNT-sheet-on-glass substrates, demonstrate the operation characteristics comparable to that of the conventional cell under temperature variation and ac electric field of 1?kHz. The results offer a possibility of deploying multifunctional CNT-sheet alignment layers in LC-based devices, especially in the future flexible display applications.     

Acridone alkaloids from the rhizomes of Luvunga scandens (Roxb.) Buch. Ham.

The ethyl acetate extract of the rhizomes of Luvunga scandens (Roxb.) Buch. - Ham. ex Wight &; Arn (Rutaceae) delivered one new acridone alkaloid named Luvungaside A (1) together with three known acridone alkaloids, namely 1,3-dihydroxy-2-methoxy-10-methyl-9-acridone (2), arborinine (3) and 1-hydroxy-3-methoxy-10-methyl-9-acridone (4). Compounds were reported for the first time from the species L. scandens applying various chromatography methods. Chemical structures were elucidated by IR, UV, HR-ESI-MS, NMR 1D &; 2D experiments and comparison with the literature. The cytotoxicity and hepatoprotective activity of compounds 1–4 in human hepatoma cell line HepG2 was measured by MTT assay. At 10–100?μM, compounds expressed significant hepatoprotective effect with prevention percentage ranging from 81.1% to 194.3%, compared to the positive control quercetin displaying 49.0%.     

A new simulation design of three-mode division (de)multiplexer based on a trident coupler and two cascaded 3 × 3 MMI silicon waveguides

We propose a design of a silicon three-mode (de)multiplexing device based on a trident and two cascaded 3 × 3 multimode interferometers. Input lights at fundamental, first-order, and second-order modes of transverse electric (TE) polarization are simultaneously converted to fundamental TE mode and demultiplexed at different ports at the outputs. The design is carried out through both theoretical analysis and numerical simulation using three dimensional-beam propagation method and effective index method. The results show a successful three-mode multiplexing in 100 nm wavelength range around 1550 nm with low insertion loss (< 0.71 dB) and crosstalk (? 18 dB). The proposed device also exhibit a small footprint (5 µm × 400 µm) that makes it potential for not only wavelength-division multiplexing and multimode-division multiplexing transmission systems, but also high bitrate and compact on-chip silicon photonics integrated circuits.     

Inhibition of Lipid Accumulation and Adipokine Levels in Maturing Adipocytes by Bauhinia rufescens (Lam.) Stem Bark Extract Loaded Titanium Oxide Nanoparticles

The present study reports a cost-effective, environmentally friendly method to increase the bioavailability and bio-efficacy of B. rufescens stem bark extract in the biological system via functional modification as B. rufescens stem bark nanoparticles (BR-TO₂-NPs). The biosynthesis of BR- -NPs was confirmed by UV-visible (UV-vis) and Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction analyses. The shifts in FT-IR stretching vibrations of carboxylic and nitro groups (1615 cm⁻¹), the O–H of phenolics or carboxylic acids (3405 cm⁻¹), alkanes, and alkyne groups (2925 and 2224 cm⁻¹) of the plant extract and lattice (455) indicated successful biosynthesis of BR- -NPs. Compared with the stem bark extract, 40 ng/dL dose of BR- -NPs led to a reduction in adipogenesis and an increase in mitochondrial biogenesis-related gene expressions, adiponectin-R1, PPARγC1α, UCP-1, and PRDM16, in maturing-adipocytes. This confirmed the intracellular uptake, bioavailability, and bio-efficiency of BR-TiO₂-NPs. The lipid-lowering capacity of BR-TiO₂-NPs effectively inhibited the metabolic inflammation-related gene markers, IL-6, TNF-α, LTB4-R, and Nf-κb. Further, BR-TiO₂-NPs stimulating mitochondrial thermogenesis capacity was proven by the significantly enhanced CREB-1 and AMPK protein levels in adipocytes. In conclusion, BR-TiO₂-NPs effectively inhibited lipid accumulation and proinflammatory adipokine levels in maturing adipocytes; it may help to overcome obesity-associated comorbidities.     

Mixed lead–tin perovskite films with >7 μs charge carrier lifetimes realized by maltol post-treatment

Mixed lead–tin (Pb–Sn) halide perovskites with optimum band gaps near 1.3 eV are promising candidates for next-generation solar cells. However, the performance of solar cells fabricated with Pb–Sn perovskites is restricted by the facile oxidation of Sn(ii) to Sn(iv), which induces self-doping. Maltol, a naturally occurring flavor enhancer and strong metal binding agent, was found to effectively suppress Sn(iv) formation and passivate defects in mixed Pb–Sn perovskite films. When used in combination with Sn(iv) scavenging, the maltol surface treatment led to high-quality perovskite films which showed enhanced photoluminescence intensities and charge carrier lifetimes in excess of 7 μs. The scavenging and surface treatments resulted in highly reproducible solar cell devices, with photoconversion efficiencies of up to 21.4% under AM1.5G illumination.

Maltol, a metal binding agent, effectively passivates defects on the surface of mixed lead–tin perovskite films. The carrier lifetimes of the resultant perovskite films are over 7 μs. The solar cell devices exhibit efficiencies of up to 21.4%.     

Generalized conductor-like screening model (GCOSMO) for solvation: An assessment of its accuracy and applicability

We present an assessment on the accuracy of a dielectric continuum solvation model, the generalized conductor-like screening model (GCOSMO), for predicting hydration free energies, tautomeric equilibria, and reaction profiles in solution. © 1996 John Wiley & Sons, Inc.