Metal-graphene nanostructures for SEIRA spectroscopy

Abstract

Infrared spectroscopy is widely used technique for observing bioorganic materials, but sometimes scientist have to work with small amount of investigated materials and infrared light interacts poorly with nanometric size molecules. Taking into account unique electro-optical properties of graphene and metal we demonstrated possibility to use metal-graphene nanostructures for label-free detection of thymine. It was shown that IR spectra of thymine adsorbed on the composite nanostructures, such as Au “nanostars” with graphene, is more enhanced than whenthese nanoparticles are used without graphene. The enhancement in IR absorption for complex thymine/Au/graphene depends on size of Au nanoparticlesand thymine’s molecular group.     

NMR T1–T2 correlation analysis of molecular absorption inside a hardened cement paste containing silanised silica fume

ABSTRACT

The influence of silanised silica fume addition on the pore size distribution and wettability of white cement paste was investigated using T₁–T₂ correlation nuclear magnetic resonance (NMR) relaxometry. Surface silanisation of silica fume particles was achieved by the hydrolysis reaction of APTES (3-Aminopropyltriethoxysilane) and condensation of the silanol functional groups on the surface. The methods used for characterisation of the silanised silica fume particles were scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). By adding silanised silica fume to the cement paste, the accessibility of water molecules to the porous system becomes restricted, leading to a lower permeability in comparison with the unmodified cement paste. Differential scanning calorimetry (DSC) measurements on the cement pastes saturated with Octamethylcyclotetrasiloxane confirm also that the size of inter-C–S–H and capillary pores is not influenced by the addition of silica fume in a detectable manner.     

Utilization of Rosmarinic and Ascorbic Acids for Maturation Culture Media in Order to Increase Sow Oocyte Quality Prior to IVF

The beneficial effect of antioxidant supplementation in maturation culture media of sow oocytes was evaluated by the expression quantification of apoptotic genes and the genes that ensure stability of germ cells during fertilization. The oocytes were cultivated for 44 h in conventional medium (C) or in medium supplemented with 105 µM rosmarinic acid (R) and 0.5 mM ascorbic acid (A) and classified into three quality classes by morphological observation from which the total RNA was isolated. The gene expression of Ptx3 and the apoptotic regulator p53, Bax and BCL-2 were evaluated by quantitative PCR technique. The decreased expression of the Bax gene in the A and R groups, compared to the control, indicates a protective role of antioxidants in the cells. Cell homeostasis was maintained, as reflected in the ratio of Bax/Bcl-2 in class I COCs (cumulus-oocyte complex) regardless of the experimental group, indicating minimum cellular stress. The expression of p53 genes was higher in all class III COC, but in A1 and R1 the expression was lower than in C1, and a similar Ptx-3 gene decreased significantly in groups A1, A2, A3 and R1 compared with control groups. Antioxidant supplementation showed beneficial effects on all morphological classes of pig COCs.     

An efficient and selective route to hybrid trifluoromethyl-substituted γ-lactones or fused nitrogen derivatives via cascade reactions

A straightforward, efficient and selective route for obtaining hybrid trifluoromethyl-substituted γ-lactones and fused nitrogen heterocycles is presented. The reaction could be guided either to γ-lactones with a nitrogen-containing heterocyclic skeleton (for monocyclic systems) or to fused nitrogen heterocycles (for fused bicyclic systems). A new class of γ-lactone with a nitrogen heterocyclic skeleton was obtained. Feasible reaction mechanisms involving cascade reactions are presented.     

Stochastic optimization approach of car value depreciation

This paper presents a stochastic model for a car's value and its depreciation under random repairs modeled by a Poisson process; the usage functional is defined, and the optimal selling time is estimated. Exact or approximative formulas are provided where possible. The car's value is evaluated as an asset with negative return and paying random normally distributed dividends at stochastic times, which are Erlang distributed. Copyright © 2012 John Wiley & Sons, Ltd.     

A regularity result for Calderón commutators

We present a regularity result for the Calderon commutator $[u,\mathcal H ](v)$ where $u,v$ are moduli of continuity and $\mathcal H $ is the Hilbert transform.     

Acoustical Performance of Concreted Wood Fiber Materials

In this paper, an inverse acoustical characterization for determination of porosity, flow resistivity, tortuosity and other parameters of a concreted wood material was proposed. Sound absorption measurements for a concreted wood fiber material were made in an impedance tube. Four acoustical models from literature were briefly described. Each model was fitted to the experimental data in order to compute their unknown parameters. Using a least-square method, the experimental data (sound absorption coefficient) was used to optimize the acoustical models by best-fitting the unknown parameters. The results of this paper show that the presented technique leads to reliable estimates of the physical parameters of the material. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Indoor radon levels and natural radioactivity in Turda salt mine, Romania

The purpose of the study is to evaluate the activity concentrations and distribution of natural radionuclides in Turda salt mine having in view the development on the future of the speleotherapy in this salt mine. The radon, gamma ray and gross alpha and beta radiation measurements have demonstrated the presence of low concentrations of natural radionuclides in rock salt and soil samples collected from different points of the salt mine and sustains the development of speleotherapy in this mine.     

Evaluation of the radon concentration in Ocna Dej salt mine,Romania

Measurement of radon is of interest both for the health risk assessment and development of radon therapy in enclosed spaces like as caves, mines and spas. In Romania, radon therapy is not in use, yet. The development of this treatment method in mines from our country involves primarily, the evaluation of radon levels in the salt mines. In this paper, the results of radon gas measurement that were performed at Ocna Dej salt mine (Romania) are presented. The radon measurements were performed using two systems: radon monitor Pylon AB-5 system and CIS-P5M system. The average radon concentration was found to be between 9.14 ± 5.10 Bq/m³ and 31.70 ± 2.76 Bq/m³. These radon levels are lower in comparison to those reported for mines, caves or spas in other countries where radon therapy and speleotherapy is frequently in use. Radon concentration and environmental conditions from Ocna Dej salt mine are suitable for therapeutic applications.