Solvent isotope effect (D2O) in photocatalytic systems

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The Relevance of ATR-FTIR Spectroscopy in Semiconductor Photocatalysis

Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy has a high potential for investigating a wide range of samples and systems. In photocatalysis, various interfacial phenomena can be studied using this technique, including pH-dependent adsorption and photodegradation of probe molecules. The analysis of the processes occurring at the interface of thin particle films deposited on the surface of an ATR crystal, either in the liquid or the gas phase, is perhaps the best way to elucidate the mechanism of adsorption and heterogeneous photocatalytic reactions. This chapter summarizes the recent advances and applications of ATR-FTIR techniques in semiconductor photocatalysis. A brief outlook at some of the possible investigations in this area is provided and the different proposed adsorption and photocatalytic degradation mechanisms are discussed

Aptamer-modified polymer nanoparticles for targeted drug delivery

The purpose of this study was to develop a model system for targeted drug delivery. This system should enable targeted drug release at a certain tissue in the body. In conventional drug delivery systems, drugs are often delivered unspecifically resulting in unwarranted adverse effects. To circumvent this problem, there is an increasing demand for the development of intelligent drug delivery systems allowing a tissue-specific mode of delivery. Within this study, nanoparticles consisting of two biocompatible polymers are used. Because of their small size, nanoparticles are well-suited for effective drug delivery. The small size affects their movement through cell and tissue barriers. Their cellular uptake is easier when compared to larger drug delivery systems. Paclitaxel was encapsulated into the nanoparticles as a model drug, and to achieve specific targeting an aptamer directed against lung cancer cells was coupled to the nanoparticles surface. Nanoparticles were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), and nanotracking analysis (NTA). Also their surface charge was characterized from ζ-potential measurements. Their preparation was optimized and subsequently specificity of drug-loaded and aptamer-functionalized nanoparticles was investigated using lung cancer cells. © 2016 by De Gruyter

Calcul de la probabilité d'erreur pour une chaîne de tatouage audionumérique à bruit non gaussien

- La chaîne de tatouage audionumérique étudiée peut être vue comme une chaîne de communications numériques particulière du fait du caractère non gaussien du bruit additif d'une part et du faible rapport signal à bruit variable par fenêtre d'autre part. L'objectif de cette étude est de mener un calcul théorique de la probabilité d'erreur que l'on est en mesure d'atteindre, en tenant compte de ces spécificités. Cette étude théorique est un préalable à un choix adéquat d'un système de codage canal dans un contexte de tatouage audio

In situ ATR-FTIR study of H2O and D2O adsorption on TiO2 under UV irradiation

The adsorption of water and deuterium oxide on TiO2 surfaces was investigated in the dark as well as under UV(A) irradiation using in situ ATR-FTIR spectroscopy under oxygen and oxygen free conditions. Adsorption of H2O–D2O mixtures revealed an isotopic exchange reaction occurring onto the surface of TiO2 in the dark. Under UV(A) irradiation, the amount of both OH and OD groups was found to be increased by the presence of molecular oxygen. Furthermore, the photocatalytic formation of hydroperoxide under oxygenated condition has been recorded utilizing Attenuated Total Reflection Fourier Transformed Infrared (ATR-FTIR) spectroscopy which appeared as new band at 3483 cm−1. Different possible mechanisms are discussed in terms of the source of hydroxyl groups formed and/or hydration water on the TiO2 surface for the photocatalytic reaction and photoinduced hydrophilicity.Mega-grant of the Government of the Russian Federation/Establishment of the Laboratory ‘Photoactive Nanocomposite Materials’/No. 14.Z50.31.001

Is binge watching among medical students associated with depression and anxiety?

Objectives: Investigate binge-watching (BW) behavior among students and assess its correlation with anxiety and depressive symptoms. Methods: Medical students who met the definition of BW were divided, according to their viewing frequency, into three groups: G1: once a month or less, G2: once a week or once every two weeks, and G3: twice a week or more. Beck Depression Inventory and State-Trait Anxiety Inventory were used. Results: Ninety-four participants were recruited. The prevalence of BW was 72.3%. Depression and anxiety scores didn’t differ between binge watchers and the non-binge watcher group. G2 was found to be significantly less depressed (p = 0.014) and had a lower anxiety state (p = 0.05) and anxiety trait scores (p = 0.026) than the control group. Feeling tired was the most prevalent reason to stop viewing among G3 (p = 0.001). Conclusion: Binge-watching could be when used in a specific manner, a way to cope with negative feelings.&nbsp

Mechanisms of Simultaneous Hydrogen Production and Formaldehyde Oxidation in H₂O and D₂O over Platinized TiO₂

The simultaneous photocatalytic degradation of formaldehyde and hydrogen evolution on platinized TiO₂ have been investigated employing different H₂O/D₂O mixtures under oxygen-free conditions using quadrupole mass spectrometery (QMS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The main reaction products obtained from the photocatalytic oxidation of 20% formaldehyde were hydrogen and carbon dioxide. The ratio of evolved H₂ to CO₂ was to 2/1. The HD gas yield was found to be dependent on the solvent and was maximized in a H₂O/D₂O mixture (20%/80%). The study of the solvent isotope effect on the degradation of formaldehyde indicates that the mineralization rate of formaldehyde (CO₂) decreases considerably when the concentration of D₂O is increased. On the basis of the ATR-FTIR data, the formaldehyde in D₂O is gradually converted to deuterated formic acid during UV irradiation, which was confirmed by different band shifting. An additional FTIR band at 2050 cm^–1 assigned to CO was detected and was found to increase during UV irradiation due to the adsorption of molecular CO on Pt/TiO₂. The results of these investigations showed that the molecular hydrogen is mainly produced by the reduction of two protons originating from water and formaldehyde. A detailed mechanism for the simultaneous hydrogen production and formaldehyde oxidation in D₂O is also presented