The effects of a running gravitational coupling and the entropic force on future singularities are considered. Although it is expected that the quantum corrections remove the future singularities or change the singularity type, treating the running gravitational coupling as a function of energy density is found to cause no change in the type of singularity but causes a delay in the time that a singularity occurs. The entropic force is found to replaces the singularity type $II\, \hbox {by} \overline{III} (a=\hbox {const.}, H=\hbox {const.}, \dot{H} \rightarrow \infty , p \rightarrow \infty , \rho \rightarrow \infty )$ which differs from previously known type $III$ and to remove the $w$-singularity. We also consider an effective cosmological model and show that the types $I$ and $II$ are replaced by the singularity type $III$. 相似文献
Let \(\mathfrak{A }\) be a Banach \(*\)-algebra and let \(\varphi \) be a nonzero self-adjoint character on \(\mathfrak{A }\). For a \(*\)-representation \(\pi \) of \(\mathfrak{A }\) on a Hilbert space \(\mathcal{H }\), we introduce and study strong \(\varphi \)-amenability of \(\pi \) in terms of certain states on the von Neumann algebra of bounded operators on \(\mathcal{H }\). We then give some characterizations of this notion in terms of certain positive functionals on \(\mathfrak{A }\). We finally investigate some hereditary properties of strong \(\varphi \)-amenability of Banach algebras. 相似文献
Blocking the division of tumor cells by small-molecules is currently of great interest for the design of new antitumor drugs. The interaction of a new metal complex with DNA was investigated through several techniques. Absorption spectroscopy and gel electrophoresis studies on the interaction of the Cu-complex of (2a-4mpyH)2 [Cu(pyzdc)2 (H2O)2].6 H2O with DNA have shown that this complex can bind to CT-DNA with binding constant 3.99?×?105 M?1. The cyclic voltammetry (CV) responses of the metal complex in the presence of CT-DNA have shown that the metal complex can bind to CT-DNA through partial intercalation mode and this is consistent with molecular docking analysis, quenching process and thermal denaturation experiments. The cytotoxicity of this complex has been evaluated by MTT assay. The results of cell viability assay on DU145 cell line revealed that the metal complex had cytotoxic effects. 相似文献
The work described herein employs neutral alumina as an effective catalyst for ring opening of triarylpyrylium perchlorates to corresponding aromatic cyanodienones, which have main roles in biological activities. The present porous catalyst has several advantages, it is inexpensive, thermally and mechanically stable, nontoxic, and highly resistant against organic solvents. It increases the reaction rate many fold when compared with conventional reaction conditions. Moreover, the recovered alumina can be used several times without serious decrease in activity.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
Cocamidopropyl betaine (CAPB) as a biodegradable surfactant produces a new worm-like micellar medium for rapid synthesis of dihydropyrano[2,3-c]pyrazoles via a four-component reaction of aldehydes, ethyl acetoacetate, malononitrile, and hydrazine hydrate at 50–60 °C. This zwitterionic surfactant was superior to anionic, cationic, and nonionic alternatives for accessing high yields of pure products without the use of any organic solvent. While the reaction medium was reusable, simple isolation of products, mild reaction conditions, low loading of CAPB for critical micelle concentration and short reaction times are additional advantages of this green procedure. 相似文献
In near-fault seismic zones, the vertical acceleration experienced during a strong event can be greater than horizontal acceleration. Methods to reduce horizontal acceleration are applied in various forms and are in common use. However, methods to reduce vertical acceleration, and practical protection systems for these applications, remain elusive. One strategy to protect structures, which has been demonstrated to be effective in situations where the excitation is horizontal, is to isolate the structure. For vertical excitations, this is difficult due to the need to maintain sufficient stiffness and strength in the direction of gravitational loads. The need to maintain high stiffness for gravity loading while allowing flexibility for isolation during earthquakes has led to research on the use of High-Static-Low-Dynamic Stiffness Systems (HSLDSS) and in particular Quasi-Zero Stiffness Systems (QZSS), which have zero equivalent stiffness in the equilibrium position. Although effective, the QZSS is sensitive to mistuning and prone to large deformations for relatively small increments in static load for building applications. This paper presents the results of an analytical and experimental study in which a HSLDSS isolation system carrying a payload is subject to vertical base excitation using sinusoidal as well as actual, scaled earthquake signals. Static loading tests are also presented. This isolation system consists of rigid rotating arms, horizontal and vertical springs and a vertical damper. By a suitable selection of parameters this could also serve as a QZSS. Results show that both the QZSS and HSLDSS can significantly reduce the magnification of the force as well as the transmission of the acceleration and that the HSLDSS retains stiffness at the equilibrium position. The numerical model includes friction and is solved using direct integration of the equation of motion. Experimental results from a scale model agree well theoretical predictions.
A bio-supported solid acid catalyst, cellulose-SO3H, was used for three-component reactions to synthesize 2-amino-4-aryl-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitriles, spirooxindoles, 2,3-dihydroquinazolin-4(1H)-ones, 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones, α-amidoalkyl-β-naphthols, and α-carbamato-alkyl-β-naphthols derivatives under solvent-free conditions. 相似文献
A sensitive electrochemical sensor for the determination of cysteamine(CA) was developed using a modified multiwall carbon nanotube paste electrode(MWCNTPE) with isoproterenol(ISPT) as a mediator.This modified electrode showed very high electrocatalytic activity for the anodic oxidation of CA.Under the optimized conditions,the electrocatalytic peak current showed a linear relationship with CA concentration in the range of 0.3–450.0 mmol/L with a detection limit of 0.09 mmol/L CA.The modified electrode was used for the determination of CA in real samples such as urine and drug samples. 相似文献
A new electrochemical sensor was fabricated via TiO2 nanoparticles onto a carbon paste electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studied the response of the modified electrode toward codeine. The effects of pH, modifier amount, pulse amplitude, and scan rate of potential have been examined. Using DPV, we could measure simultaneously codeine and acetaminophen in one mixture. The detection limits of 0.018 and 0.050 µmol L?1 were achieved for codeine and acetaminophen, respectively. The electrooxidation pathway, transfer coefficient, and standard rate constant, are estimated. The proposed voltammetric sensor was successfully applied to determination of codeine and acetaminophen in human plasma serum samples. 相似文献