The synthesis of N-derivatives of 3-aminoperylene and their absorption and fluorescence properties

N-Acetyl and N-triazinyl 3-aminoperylenes were prepared. N-(4,6-Dichloro-1,3,5-triazin-2-yl)-3-aminoperylene was synthesized by the condensation of 3-aminoperylene with cyanuric chloride; other N-triazinyl derivatives were prepared by the successive substitution of chlorine atoms with methoxy or aniline groups. The structure and purity of the compounds were confirmed by elemental analysis, NMR spectroscopy and mass spectrometry. The UV/vis absorption, fluorescence and excitation spectra as well as the fluorescence quantum yields for the compounds were measured in dibutyl ether, 1,4-dioxane, ethyl acetate and acetonitrile; fluorescence lifetimes were measured in ethyl acetate and dimethyl sulfoxide. The influences of both the character of the N-substituent and the solvent polarity upon the spectra and quantum yields are discussed.     

Electrochemical synthesis and characterization of Fe70Pd30 nanotubes for drug-delivery applications

Fe–Pd-based tubular nanostructures were prepared by direct electrodeposition into track-etched polycarbonate templates. The characterization of the electrodeposition process showed that the complexing of Pd and Fe is necessary for the co-deposition of both metals. In the as-deposited nanotubes, which exhibited an overall composition of Fe₇₀Pd₃₀ as determined by SEM/EDS, a gradient in the composition along the tubes was observed using a detailed TEM/EDS analysis. This was attributed to potentiostatic nature of the deposition and to different kinetic properties at the beginning of the reaction, and later on, when the reaction is diffusion controlled, to different transport properties (diffusion and convection) of the involved ionic species. The magnetic measurements showed that the Fe₇₀Pd₃₀ nanotubes are ferromagnetic with a high magnetization saturation of 170 emu g⁻¹, which makes them suitable for drug-delivery applications. The Fe₇₀Pd₃₀ nanotubes were successfully functionalized with a model drug, paracetamol. The proposed type of release, with an initial burst and a slower release of the remaining drug, could be suitable for applications where a fast action is required, which then has to be maintained for a certain time period.     

Lattice dynamics and Raman spectrum of rutile TiO2: The role of soft phonon modes in pressure induced phase transition

Using the plane-wave pseudopotential technique based on the first-principles density functional perturbation theory (DFPT), we have studied the vibrational properties and Raman susceptibility tensor at ambient and high pressure of rutile phase of TiO₂. Full phonon dispersion curves and phonon densities of states with projected phonon density of states and Raman tensors at high pressures are calculated and given. It is found that rutile TiO₂ shows a pressure induced phase transition, especially when lattice dynamical instabilities are involved, like the soft phonon modes, at a hydrostatic pressure lower than 10 GPa. An analyses of the vibrational displacements is given. The possibility to use Raman line intensities as an additional tool in the study of phase transitions is also discussed.     

The districts of Lithuania with low heat demand density: A chance for the integration of straw biomass

District heating sector is one of the most important sectors of Lithuanian energy industry. Consequently, low-cost bioenergy sources could play an important role in developing biofuels based on the so-called second-generation feedstock and decentralized energy supply for remote rural areas with low heat demand density. The present amount of biomass straw is already considerable in Lithuania but the potential is even much higher. It is assumed that the share of firewood in the balance of RES will decrease significantly – from 86.7% in 2009 to 55% in 2020 and future decisions on the acceptability of new substitutes must be found. The most important factors that could hasten the diffusion of straw combustion technologies for heat-only boilers (HOBs) in order to contribute to a local fuel and low-emission energy infrastructure are political issues, reduction in existing technical thresholds, market and economic conditions, international cooperation activity, and broad experience through wood residue combustion.The collected data indicated that under conditions in Lithuania, biomass straw combustion is prospective mainly to be used for heat production in small and medium scale units of 0.6–5.0 MW_th capacity as well as in large scale installations where multi-biomass strategies are foreseen.     

Copper oxide nanowires: a review of growth

Cuprous oxide (Cu(2)O) and cupric oxide (CuO) nanowires have started playing important roles in energy conversion devices and optoelectronic devices. Although the desired advanced properties have been demonstrated, these materials cannot yet be produced in large-bulk quantities in order to bridge the technological transfer gap for wider use. In this respect, the quest for the most efficient synthesis process which yields not only large quantities but also high quality and advanced material properties continues. This paper gives an extensive review of copper oxide nanowire (NW) synthesis by all methods and routes by which various researchers have obtained their nanomaterial. These methods are critically overviewed, evaluated and compared. Methods of copper oxide NW growth include wet-chemical methods based on pure solution growth, electrochemical and hydrothermal routes as well as thermal and plasma oxidation methods. In terms of advanced nanowire synthesis, the fast thermal method or direct plasma oxidation as well as the combined hybrid wet-chemical method in which copper hydroxide NWs are produced and sequentially transformed by plasma oxidation which produces Cu(2)O NWs are seen as the most promising methods to explore in the near future. These methods not only yield large quantities of NWs, but produce high quality material with advanced properties.     

A simple drug anchoring microfiber scaffold for chondrocyte seeding and proliferation

The structural properties of microfiber meshes made from poly(2-hydroxyethyl methacrylate) (PHEMA) were found to significantly depend on the chemical composition and subsequent cross-linking and nebulization processes. PHEMA microfibres showed promise as scaffolds for chondrocyte seeding and proliferation. Moreover, the peak liposome adhesion to PHEMA microfiber scaffolds observed in our study resulted in the development of a simple drug anchoring system. Attached foetal bovine serum-loaded liposomes significantly improved both chondrocyte adhesion and proliferation. In conclusion, fibrous scaffolds from PHEMA are promising materials for tissue engineering and, in combination with liposomes, can serve as a simple drug delivery tool.     

Green Synthesis of Acetals/Ketals: Efficient Solvent-Free Process for the Carbonyl/Hydroxyl Group Protection Catalyzed by SBA-15 Materials

Acetals/ketals derived from the aldehydes/ketones are easily prepared under solventless conditions. The process is heterogeneously catalysed using acid or basic mesoporous molecular sieves Al-SBA-15 and (Cs)Al-SBA-15. The catalytic procedure herein reported is applied to the preparation of the key intermediates for the synthesis of {3-[(2R,3R,4R,5R)-(2,3,4,5-tetrahydroxyhexane-1,6-diyl)]}di-1H-imidazole 2 with potential biomedical applications.     

Effect of input excitation on the quality of empirical dynamic models for type 1 diabetes

Accurate prediction of future blood glucose trends has the potential to significantly improve glycemic regulation in type 1 diabetes patients. A model‐based controller for an artificial β‐cell, for example, would determine the most efficacious insulin dose for the current sampling interval given available input–output data and model predictions of the resultant glucose trajectory. The two inputs most influential to the glucose concentration are bolused insulin and meal carbohydrates, which in practice are often taken simultaneously and in a specified ratio. This linear dependence has adverse effects on the quality of linear dynamic models identified from such data. On the other hand, inputs with greater degrees of excitation may force the subject into extreme hypoglycemia or hyperglycemia, and thus may be clinically unacceptable. Inputs with good excitation that do not endanger the subject are shown to result in models that can predict glucose trends reasonably accurately, 1–2 h ahead. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Numerical analysis of the tubular heat exchanger designed for co-generating units on the basis of microturbines

The application of numerical simulations using the computational fluid dynamics (CFD) analysis when mapping processes in the course of which the heat transmission occurs has become an essential part of the heat transfer systems. The present contribution deals with the possibility to use the waste heat of the flue gas produced by small microturbines. The waste heat is mapped by means of both the numerical simulations applying the FLUENT software and the practical experiment. Utilizing a part of the waste heat for water heating and decreasing the outlet temperature of the flue gas into atmosphere when applying in co-generating units represents one of the partial benefits. The present paper brings information concerning the newly designed type of heat exchanger including the results of its numerical analysis.The analysed heat exchanger designed in the system with microturbine (MT) C30 reached generally the efficiency of 75%. Both the results of simulations and the carried out practical experiment confirmed the temperature of the flue gas to be sufficient behind the exchanger to prevent the condensation of water from the flue gas. On the contrary, except for heating water the exchanger under consideration offers – thanks to its design – also other possibilities to use of the flue gas. The practical experiment confirmed the results of the CFD prediction with rather small differences as the temperature of water obtained from the exchanger was 359 K and the designed shape of the exchanger did not result in substantial pressure losses in flue gas approximately 50 Pa. The mean logarithmic temperature difference of the mapped and verified exchanger was ～203 K.