Phase behaviour of transkarbam 12

Transkarbam 12 (T12), the carbamic acid salt of omega-aminocaproic acid dodecyl ester, is a recently synthesized substance, whose high permeation enhancing activity through the human skin was found for certain drugs. In this work, the thermotropic phase behaviour of T12 has been studied by means of various techniques, namely, DSC, FTIR and FT-Raman spectroscopy, X-ray powder diffraction, and DRS. The temperature development of the X-ray reflections as well as of the conformationally sensitive Raman bands and the IR bands have been observed. At room temperature, the hydrocarbon chains of T12 exhibit a highly ordered structure, arranged in an orthorhombic perpendicular subcell. On heating, two transitions occur at 54 and at 66 degrees C. The first transition is related to the disruption of the carbamate structure and changes in the polar head group. The other transition represents the melting of hydrocarbon chains and the subsequent release of carbon dioxide. The time required for the rebinding of carbon dioxide and the reformation of the carbamate structure is dependent upon numerous factors and it was not possible to precisely determine the length of this process.     

Synthesis and characterization of bdmppdcbpyRu (II) complex for dye-sensitized solar cells [where bdmpp is 2,6-bis(3,5-dimethyl-N-pyrazoyl)pyridine and dcbpy is 2,2′-bipyridine-4,4′-dicarboxylic acid]

A new complex, [Ru(II)(dcbpyH₂)(bdmpp)Cl](PF₆) (where bdmpp is 2,6-bis(3,5-dimethyl-N-pyrazoyl)pyridine, dcbpyH₂ is 2,2′-bipyridine-4,4′-dicarboxylic acid) is synthesized and characterized by mass spectroscopy, by IR, ES-MS and ¹H NMR (1D and 2D) spectroscopies. The broad and very high intensity MLCT absorption band in the visible makes this dye potentially beneficial for the photosensitization process. Cyclic voltammetry analysis displays a well reversible oxidation-reduction wave with E_1/2=+0.81 vs. Ag-AgCl. Transparent TiO₂ thin film electrodes can easily be chemically modified by the complex and the incorporation of the resulting photoelectrodes in wet regenerative solar cells produced a stable photovoltage of 550 mV and gave a continuous photocurrent of 140 μA cm⁻².     

Phase transitions in crystals of racemic long chain 2-amino alcohols

Various techniques, namely differential scanning calorimetry, optical microscopy, dielectric and Raman spectroscopy, all covering a wide range of temperatures, were used to study the thermodynamically stable phases and molecular mobility of crystals of long chain 2-amino alcohols. The results showed that two different crystal forms are present in each sample. The temperature behaviour of the phases is studied in details.     

Solution‐Processed Hydrogen Molybdenum Bronzes as Highly Conductive Anode Interlayers in Efficient Organic Photovoltaics

Highly efficient and stable organic photovoltaic (OPV) cells are demonstrated by incorporating solution‐processed hydrogen molybdenum bronzes as anode interlayers. The bronzes are synthesized using a sol‐gel method with the critical step being the partial oxide reduction/hydrogenation using an alcohol‐based solvent. Their composition, stoichiometry, and electronic properties strongly correlate with the annealing process to which the films are subjected after spin coating. Hydrogen molybdenum bronzes with moderate degree of reduction are found to be highly advantageous when used as anode interlayers in OPVs, as they maintain a high work function similar to the fully stoichiometric metal oxide, whereas they exhibit a high density of occupied gap states, which are beneficial for charge transport. Enhanced short‐circuit current, open‐circuit voltage and, fill factor, relative to reference devices incorporating either PEDOT‐PSS or a solution processed stoichiometric molybdenum oxide, are obtained for a variety of bulk heterojunction mixtures based on different polymeric donors and fullerene acceptors. In particular, high power conversion efficiencies are obtained in devices that employed the s‐H_xMoO_2.75 as the hole extraction layer.     

Minimizing Energy Losses in Dye‐Sensitized Solar Cells Using Coordination Compounds as Alternative Redox Mediators Coupled with Appropriate Organic Dyes

To further boost the efficiency of dye‐sensitized solar cells, a correct evaluation of the real limitations of this type of solar cell should be conducted. From a simple analysis of the photovoltaic data found in the literature, it is evident that the V_oc decrease, through energy losses, seems to be the most crucial factor diminishing the overall system efficiency. In particular, losses arising from the regeneration of the dye by the iodide/triiodide redox mediator are huge. The most convenient manner to recuperate these losses is the use of alternative redox mediators with more positive redox potentials than that of the iodide‐based shuttle. Among various types of redox active compounds, ferrocene/ferrocenium, Cu^+/2+, and Co^2+/3+ complexes are found to be the most effective in solar cells and the obtained efficiencies of more than 12% clearly show that a breakthrough is close, paving revolutionary roads towards making new records.     

Role of oxidative stress and DNA damage in human carcinogenesis

Cells in tissues and organs are continuously subjected to oxidative stress and free radicals on a daily basis. This free radical attack has exogenous or endogenous (intracellular) origin. The cells withstand and counteract this occurrence by the use of several and different defense mechanisms ranging from free radical scavengers like glutathione (GSH), vitamins C and E and antioxidant enzymes like catalase, superoxide dismutase and various peroxidases to sophisticated and elaborate DNA repair mechanisms. The outcome of this dynamic equilibrium is usually the induction of oxidatively induced DNA damage and a variety of lesions of small to high importance and dangerous for the cell i.e. isolated base lesions or single strand breaks (SSBs) to complex lesions like double strand breaks (DSBs) and other non-DSB oxidatively generated clustered DNA lesions (OCDLs). The accumulation of DNA damage through misrepair or incomplete repair may lead to mutagenesis and consequently transformation particularly if combined with a deficient apoptotic pathway. In this review, we present the current status of knowledge and evidence on the mechanisms and involvement of intracellular oxidative stress and DNA damage in human malignancy evolution and possible use of these parameters as cancer biomarkers. At the same time, we discuss controversies related to potential artifacts inherent to specific methodologies used for the measurement of oxidatively induced DNA lesions in human cells or tissues.     

Glass Transition and Dynamics in Lysozyme�CWater Mixtures Over Wide Ranges of Composition

Differential scanning calorimetry (DSC) and two dielectric techniques, broadband dielectric relaxation spectroscopy and thermally stimulated depolarization currents (TSDC), were employed to study glass transition and water and protein dynamics in mixtures of water and a globular protein, lysozyme, in wide ranges of water content, both solutions, and hydrated solid samples. In addition, water equilibrium sorption isotherms (ESI) measurements were performed at room temperature. The main objective was to correlate results by different techniques to each other and to determine critical water contents for various processes. From ESI measurements the content of water directly bound to primary hydration sites was determined to 0.088 (grams of water per grams of dry protein), corresponding to 71 water molecules per protein molecule, and that where clustering becomes significant to about 0.25. Crystallization and melting events of water were first observed at water contents 0.270 and 0.218, respectively, and the amount of uncrystallized water was found to increase with increasing water content. Two populations of ice crystals were observed by DSC, primary and bulk ice crystals, which give rise to two separate relaxations in dielectric measurements. In addition, the relaxation of uncrystallized water was observed, superimposed on a local relaxation of polar groups on the protein surface. The glass transition temperature, determined by DSC and TSDC in rather good agreement to each other, was found to decrease significantly with increasing water content and to stabilize at about −90 °C for water contents higher than about 0.25. This is a novel result of this study with potential impact on cryoprotection and pharmaceutics.     

CLEAN WATER: water detoxification using innovative photocatalysts

Environmental pollution abatement and especially the growing demand for clean water pose one of the most severe challenges worldwide. Besides the scarcity of water resources, the presence of hazardous chemicals with serious adverse health effects, even at extremely low concentrations, impose serious considerations for the quality of drinking water. The rapid evolution of nanoscale science and technology has dramatically expanded the materials’ application potential towards radically new or multifunctional properties rendering nanotechnology an indispensable component in shaping modern environmental science. The nanoscale-perspective maintaining the integrity of the environment is currently the stimulus for the development of innovative and cost-effective functional materials and sustainable processes for water treatment and purification. The CLEAN WATER (EU FP7 collaborative project) aims at the development of an innovative and efficient water detoxification technology exploiting solar energy and nano-engineered titania photocatalysts in combination with nanofiltration membranes. In this approach, nanostructured titania with high UV–visible response will be synthesized and stabilized on nanotubular membranes of controlled pore size and retention efficiency as well as on carbon nanotubes exploiting their high surface area to achieve photocatalytically active nanocomposite membranes. Comparative evaluation of the UV–visible and solar light efficiency of the modified titania photocatalysts for water detoxification will be intensively investigated on various target pollutants ranging from classical water contaminants such us phenols, pesticides and azo-dyes to the extremely hazardous cyanobacterial toxins and emerging endocrine disrupting compounds in order to evaluate/optimize the materials performance and validate their competence on water treatment. Particular efforts will be devoted to the analysis and quantification of degradation products as well as their toxicity. All these will be the crucial components for the fabrication of innovative continuous flow photocatalytic-disinfection-membrane reactors for the implementation of sustainable and cost effective water treatment technologies based on nano-engineered materials.