ON PSEUDOSYMMETRY TYPE HYPERSURFACES OF SEMI-EUCLIDEAN SPACES Ⅰ

In this paper the authors investigate hypersurfaces M of a semi-Euclidean space Esn+1, n ≥ 4, satisfying (aC +βR). H ＝ LkQ(g, Hk), k ＝ 1,2,3. Using obtained results they show additional curvature properties of investigated hypersurfaces.     

Toward three-dimensional nanoengineering of heterogeneous catalysts

Cobalt-based Fischer-Tropsch systems are widely used to convert synthesis gas to clean hydrocarbon fuel. However, surprisingly little is known about the morphology of the catalysts on the nanoscale. Here we show that scanning transmission electron tomography reveals their true 3-D morphology and provides direct evidence that the support controls the final morphology of the catalyst. Such direct local three-dimensional measurements provide unprecedented insight into catalysis, and can henceforth transform our understanding of these complex materials.     

Poly(trifluoroethylene) adsorption and heterogeneous photochlorination reactions

Heterogeneous (gas-solid) photochlorination reactions of poly(trifluoroethylene) (PF 3E) films were studied as a function of reaction time and light intensity. The rate of chlorination was found to be faster in high-intensity light when compared to the reaction in ambient light. PF 3E irreversibly adsorbed to oxidized silicon and covalently attached amine monolayers supported on silicon, producing hydrophobic thin films in the thickness range of 8-40 A. Adsorption conditions such as polymer concentration and solvent composition were investigated. Radical grafting of maleic anhydride to the polymer backbone resulted in increased adsorption on oxidized silicon.     

Stability of an $$\varvec{}{}$$th root functional equation in $$\varvec{C}^{*}$$C∗-algebras: a fixed point approach

In this paper, we introduce an \(m{\text{th}}\) root functional equation. Using the fixed point approach, we prove the Hyers–Ulam stability of the \(m{\text{th}}\) root functional equation in \(C^{*}\)-algebras.     

Charge-transfer complex formation between p-chloranil and 1,n-dicarbazolylalkanes

Dimer model compounds of polyvinylcarbazoles (1,n-di(N-carbazolyl)alkanes, when n=1-5) were synthesized to model the effects of distance and orientation between carbazole groups in polymeric systems. Charge-transfer (CT) complexes of carbazole, N-ethylcarbazole and 1,n-di(N-carbazolyl)alkanes with p-chloranil (p-CHL) have been investigated spectrophotometrically in dichloromethane. The colored products are measured spectrophotometrically at different wavelength depending on the electronic transition between donors and acceptor. The formation constants of the CT complexes were determined by the Benesi-Hildebrand equation. The thermodynamic parameters were calculated by Van't Hoff equation. Stochiometries of the complexes formed between donors and acceptor were defined by the Job's method of the continuous variation and found in 1:1 complexation with donor and acceptor at the maximum absorption bands.     

Vranceanu surface in $$ \mathbb{E}^4 $$ with pointwise 1- type Gauss map

In this article we investigate Vranceanu rotation surfaces with pointwise 1- type Gauss map in Euclidean 4-space $ \mathbb{E}^4 $ \mathbb{E}^4 . We show that a Vranceanu rotation surface M has harmonic Gauss map if and only if M is a part of a plane. Further, we give necessary and sufficent conditions for Vranceanu rotation surface to have pointwise 1-type Gauss map.     

Lower limits of detection in speciation analysis by coupling high-performance liquid chromatography and chemical-vapor generation

Speciation studies are much more important than total element determination because toxicity of many elements depends on their chemical forms. Nobody can claim that a foodstuff is very dangerous to eat by determining total arsenic due to the possibility that the arsenic could be present in non-toxic forms. Hence, speciation studies are crucial in any matrix relevant to human beings.Trace-element speciation requires sufficiently sensitive procedures to monitor each species at trace levels. One way to increase the sensitivity for elements forming volatile species is coupling high-performance liquid chromatography (HPLC) with chemical-vapor generation (CVG). This review aims to highlight not only development of HPLC-CVG techniques for ultratrace-elemental speciation in a variety of matrices but also their application. In addition, we discuss the advantages and the disadvantages of these techniques.     

Aflatoxin species: their health effects and determination methods in different foodstuffs

Carcinogenic and mutagenic properties of aflatoxin species are known in literature. Their intake over a long time period might be health-dangerous for human even at trace levels. It is well known that different foodstuffs can be contaminated by aflatoxin species through growing and storage. Due to the serious health effects, sensitive determination of aflatoxin species in any matrices related with the human being is very crucial at trace levels. In literature, there are sensitive techniques to analyze the different samples for the contents of their aflatoxin species. Each technique has some advantages and disadvantages over the other techniques. This review aims to summarize the different health effects of aflatoxin species, development of analytical techniques and applications of developed techniques in a variety of matrices.      

Conformational analysis and vibrational spectroscopic investigation of 3-phenylpropylamine

The possible stable forms of 3-phenylpropylamine (3-PPA) molecule were experimentally and theoretically studied by infrared and Raman spectroscopy. FT-IR and Raman spectra of 3-PPA were recorded in the regions of 4000–400 cm⁻¹ and 3700–60 cm⁻¹, respectively. The potential energy surface corresponding to the internal rotations of the molecule was investigated by semi-empirical quantum mechanical methods, and appropriate conformers defined with B3LYP hybrid density functional theory method along with the basis sets of different size and type. Results from experimental and theoretical data showed the trans–trans–gauche (TTG) to be the most stable form of a 3-PPA molecule.     

Development of a water-soluble 3-formylBODIPY dye for fluorogenic sensing and cell imaging of sulfur dioxide derivatives

A new water-soluble, highly fluorogenic 3-formylBODIPY dye that enables the sensing of SO₂ derivatives in aqueous buffers and cancer cells is reported. The quaternary ammonium group appended through the meso-position of the BODIPY dye ensures water solubility. The probe exhibits high specificity for cytosolic (bi)sulfites and fluoresces brightly in human lung adenocarcinoma cells (A549).