Evaluation of commercially available polylactic acid (PLA) filaments for 3D printing applications

Journal of Thermal Analysis and Calorimetry - Polylactic acid (PLA) is a biodegradable and bioresorbable biopolymer that has successfully been applied in biomedical and related fields. It is in the...     

Thiuroniumderivate der Pyridoxingruppe

Ohne Zusammenfassung     

Techniques of signal generation required for electropermeabilization. Survey of electropermeabilization devices

Electropermeabilization is a phenomenon that transiently increases permeability of the cell plasma membrane. In the state of high permeability, the plasma membrane allows ions, small and large molecules to be introduced into the cytoplasm, although the cell plasma membrane represents a considerable barrier for them in its normal state. Besides introduction of various substances to cell cytoplasm, permeabilized cell membrane allows cell fusion or insertion of proteins to the cell membrane. Efficiency of all these applications strongly depends on parameters of electric pulses that are delivered to the treated object using specially developed electrodes and electronic devices--electroporators. In this paper we present and compare most commonly used techniques of signal generation required for electropermeabilization. In addition, we present an overview of commercially available electroporators and electroporation systems that were described in accessible literature.     

Characteristics of diluted magnetic semiconductor based on Mn-doped TiO2 nanorod array films

Journal of Solid State Electrochemistry - In this work, un-doped and Mn-doped TiO2 nanorod (NR) array films were successfully prepared by hydrothermal method that deposited on FTO substrate at...     

Evolution of structural properties of iron oxide nano particles during temperature treatment from 250 °C-900 °C: X-ray diffraction and Fe K-shell pre-edge X-ray absorption study

Iron oxide nano particles with nominal Fe₂O₃ stoichiometry were synthesized by a wet, soft chemical method with heat treatment temperatures from 250 °C to 900 °C in air. The variation in the structural properties of the nano particles with the heat treatment temperature was studied by X-ray diffraction and Fe K-shell X -ray absorption spectroscopy. X-ray diffractograms show that at lower annealing temperatures the nano particle comprise both maghemite and hematite phases. With increasing temperature, the remainder of the maghemite phase transforms completely to hematite. Profile analysis of the leading Bragg reflections reveals that the average crystallite size increases from 50 nm to 150 nm with increasing temperature. The mean primary particle size decreases from 105 nm to 90 nm with increasing heat treatment temperature. The X-ray diffraction results are paralleled by systematic changes in the pre-edge structure of the Fe K-edge X-ray absorption spectra, in particular by a gradual decrease of the t_2g/e_g peak height ratio of the two leading pre-edge resonances, confirming oxidation of the Fe from Fe²⁺ towards Fe³⁺. Transmission electron microscopy (TEM) on the samples treated at temperatures as high as 900 °C showed particles with prismatic morphology along with the formation of stacking fault like defects. High resolution TEM with selected area electron diffraction (SAED) of samples heat treated above 350 °C showed that the nano particles have well developed lattice fringes corresponding to that of (110) plane of hematite.     

Transformation of Organic Solvents into Carbon-Based Materials by Liquid-Phase Plasmas

The possibility of modifying chemical properties of organic liquids under the influence of strong electric fields created by pulsed electrical discharges with energies on the order of J/pulse is quite intriguing. Considering the majority of carbon-based materials today are almost exclusively synthesized from gaseous precursors, the realization of this process even seems necessary. The goal of this study was to examine the possibility of synthesizing carbon materials using streamer-like electrical discharges in three different organic liquids: methanol, acetone and pentane. The morphology of the deposited carbon was imaged using scanning electron microscopy whereas energy dispersive X-ray spectroscopy was used to analyze chemical composition of the resulting films and particles. The results have shown that electrical discharges in all three liquids result in the carbon deposition on the high-voltage electrode. Depending on the type of the organic liquid, the thickness of the carbon layer deposited on the electrode can rise 10?C70?% above baseline levels and the deposition is accompanied by a change in surface morphology of the electrode. Electrical discharges in acetone and pentane also result in the deposition of solid carbon particles in the bulk liquid. The mechanism for the formation of solid carbon byproducts was correlated with chemical reactions in plasma.     

Use of novel cardanol-porphyrin hybrids and their TiO₂-based composites for the photodegradation of 4-nitrophenol in water

Cardanol, a well known hazardous byproduct of the cashew industry, has been used as starting material for the synthesis of useful differently substituted "cardanol-based" porphyrins and their zinc(II), copper(II), cobalt(II) and Fe(III) complexes. Novel composites prepared by impregnation of polycrystalline TiO? powder with an opportune amount of "cardanol-based" porphyrins, which act as sensitizers for the improvement of the photo-catalytic activity of the bare TiO?, have been used in the photodegradation in water of 4-nitrophenol (4-NP), which is a toxic and bio-refractory pollutant, dangerous for ecosystems and human health.     

An algorithm for mean residual life computation of (n − k + 1)-out-of-n systems: An application of exponentiated Weibull distribution

In this paper, we establish an algorithm for the computation of the mean residual life of a (n − k + 1)-out-of-n system in the case of independent but not necessarily identically distributed lifetimes of the components. An application for the exponentiated Weibull distribution is given to study the effect of various parameters on the mean residual life of the system. Also the relationship between the mean residual life for the system and that of its components is investigated.