Fiber diameter in electrospinning process

In order to increase the control on the fiber diameter we propose in this paper a methodology to determine stability domains of the process in which the electrospun fiber diameter can be predetermined and also controlled by means of the polymer solution flow and the applied voltage. To define these stability domains we employ a combination of analytical expressions depending on the location along the traveling jet. In the vicinity of the nozzle we employ the expression which links the fiber diameter with the kinematic viscosity of the polymer solution, nozzle-collector distance, solution density, liquid flow, electric current and intensity of the electrostatic field. At larger distances from the nozzle, the fiber diameter can be expressed as a function of solution density, liquid flow, intensity of the applied electrostatic field and distance from the nozzle. Close to the collector the fiber diameter can be expressed with respect to the superficial tension of the polymer solution, dielectric permittivity, liquid flow and intensity of the electric current. Under specific constrains, the superposition of the plots obtained from these mathematical expressions will be used to determine the stability domain for the fiber diameter in which the diameter can be controlled by two process parameters, namely applied voltage and polymer solution flow. Through this approach the present paper can contribute to increased control of the electrospinning process and thus enhanced applicability.     

Al2O3/TiO2 hybrid nanofluids thermal conductivity

Journal of Thermal Analysis and Calorimetry - This research deals with experimental studies on thermal conductivity variation of Al2O3 and TiO2 hybrid nanofluids with water as the base fluid. In...     

C1‐Symmetric Aminosulfoximines in Copper‐Catalyzed Asymmetric Vinylogous Mukaiyama Aldol Reactions

Vinylogous Mukaiyama‐type aldol reactions have been catalyzed by a combination of Cu(OTf)₂ and readily available C₁‐symmetric aminosulfoximines. After a fine‐tuning of the reaction conditions and an optimization of the modularly assembled ligand structure, high stereoselectivities and excellent yields have been achieved in catalyzed reactions involving various electrophile/nucleophile combinations. The relative and absolute configurations of two products were assigned by X‐ray single crystal structure analysis and a comparison of calculated and experimental CD spectra.     

AutoPPI: An Ensemble of Deep Autoencoders for Protein–Protein Interaction Prediction

Proteins are essential molecules, that must correctly perform their roles for the good health of living organisms. The majority of proteins operate in complexes and the way they interact has pivotal influence on the proper functioning of such organisms. In this study we address the problem of protein–protein interaction and we propose and investigate a method based on the use of an ensemble of autoencoders. Our approach, entitled AutoPPI, adopts a strategy based on two autoencoders, one for each type of interactions (positive and negative) and we advance three types of neural network architectures for the autoencoders. Experiments were performed on several data sets comprising proteins from four different species. The results indicate good performances of our proposed model, with accuracy and AUC values of over 0.97 in all cases. The best performing model relies on a Siamese architecture in both the encoder and the decoder, which advantageously captures common features in protein pairs. Comparisons with other machine learning techniques applied for the same problem prove that AutoPPI outperforms most of its contenders, for the considered data sets.     

Microstructures and growth characteristics of polyelectrolytes on silicon using layer-by-layer assembly

Growth processes of nanocomposite layers obtained by polyelectrolytes, poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC), self-assembled on silicon surface using layer-by-layer (LbL) technique were investigated, and theoretical and experimental data are herein reported. Complementary microstructural and compositional analyses techniques (scanning electron microscopy, ellipsometry, X-ray reflectivity, zeta (ξ) potential measurements and attenuated total reflection infrared spectroscopy) were used for deep characterization of the multilayer structure formation. Electrophoretic zeta (ξ) potential measurements indicated that the surface charge was either positive or negative, depending on the polyelectrolyte used (PDADMAC or PSS). ATR-IR spectra confirmed the successfully silanization process and then, the building up of the nanocomposite layer. Morphological investigation and X-ray reflectivity demonstrated the growth process and cross-section size of the bilayers. Ellipsometric measurements were in very good agreement with SEM and XRR, showing once again the successful deposition of polyelectrolyte multilayers.      

Microwave-assisted extraction of trichloroethylene from clay samples

A new method for volatile organic compounds (VOCs) extraction from low-permeability media, such as clay, has been developed and tested using trichloroethylene (TCE) as a model compound. The method is based on microwave-assisted extraction (MAE), which uses microwave energy to heat the extracting solvent and the sample. MAE allows the extraction process to be carried out at elevated temperatures and pressures, which dramatically reduces the time required to complete the process. A custom-made PTFE vessel was used for extraction investigations. TCE analysis was performed using gas chromatography with electron capture detection (GC-ECD). Three different solvents were tested: methanol, 1?:?1 hexane?:?acetone mixture, and 10?:?1 hexane?:?acetone mixture. A comparison of TCE recoveries from clay samples using the new method and the standard methanol extraction method was carried out. The newly developed method and the method currently in use were found to recover similar amounts of TCE. The major advantage of the MAE technique is the very short time needed to obtain complete analyte recovery (6–10?min), which makes it possible to analyse a large number of samples without the need for sample preservation or prolonged storage. Thus, the new method is much more efficient than the existing methods. The technique has a good potential for field application.     

A numerical approximation of parabolic stochastic partial differential equations driven by a Poisson random measure

The paper deals with SPDEs driven by Poisson random measures in Banach spaces and its numerical approximation. We investigate the accuracy of space and time approximation. As the space approximation we consider spectral methods and as time approximation the implicit Euler scheme and the explicit Euler scheme. AMS subject classification (2000) 60H15, 35R30     

Determination of the anchoring constant for a compensated binary cholesteric mixture

The optical transmission and the electric power was simultaneously recorded for the binary compensated cholesteric mixture cholesteryl chloride + cholesteryl nonanoate (70:30 molar). The values of the critical voltages U₁ and U₂ (at which the planar texture changes into a conic focal one, and the cholesteric-nematic transition take place) at different temperatures were obtained. The temperature dependence of the anchoring constant is determined.