A quantum-chemical investigation on the structural and opto-electronic properties of several alkoxy substituted 4,4′-bis(2-phenylethenyl)biphenyls (PEBP) as building blocks for π-conjugate polymer is performed in order to display the effect of changing the position of alkoxy substituents on the peripheral phenyl rings on their opto-electronic and physico-chemical properties. Added to the good agreement between theoretical and experimental observations, it has been observed that the substitution effect depends on the position of the methoxy group: in ortho- or para-positions it acts as a mesomeric electrons donor, while as an inductive electrons acceptor in meta-positions. Substitution in ortho-positions causes significant structural deformations of PEBP backbone due to the steric interaction between the substituents and the hydrogens of the vinylene functions. Bridging of ortho, para-PEBP (24PEBP) by CC(CN)2 decreases significantly its band gap. This model can have very interesting opto-electronic ownerships. 相似文献
Type 1 secretion systems (T1SS) have a relatively simple architecture compared to other classes of secretion systems and therefore, are attractive to be optimized by protein engineering. Here, we report a KnowVolution campaign for the hemolysin (Hly) enhancer fragment, an untranslated region upstream of the hlyA gene, of the hemolysin T1SS of Escherichia coli to enhance its secretion efficiency. The best performing variant of the Hly enhancer fragment contained five nucleotide mutations at five positions (A30U, A36U, A54G, A81U, and A116U) resulted in a 2-fold increase in the secretion level of a model lipase fused to the secretion carrier HlyA1. Computational analysis suggested that altered affinity to the generated enhancer fragment towards the S1 ribosomal protein contributes to the enhanced secretion levels. Furthermore, we demonstrate that involving a native terminator region along with the generated Hly enhancer fragment increased the secretion levels of the Hly system up to 5-fold. 相似文献
In this review, flat plate and concentrate-type solar collectors, integrated collector–storage systems, and solar water heaters combined with photovoltaic–thermal modules, solar-assisted heat pump solar water heaters, and solar water heaters using phase change materials are studied based on their thermal performance, cost, energy, and exergy efficiencies. The maximum water temperature and thermal efficiencies are enlisted to evaluate the thermal performance of the different solar water heaters. It is found that the solar water heaters’ performance is considerably improved by boosting water flow rate and tilt angle, modification of the shape and number of collectors, using wavy diffuse and electrodepositioned reflector coating, application of the corrugated absorber surface and coated absorber, use of turbulent enhancers, using thermal conductive working fluid and nanofluid, the inclusion of the water storage tank, and tank insulation. These items increase the heat transfer area and coefficient, thermal conductivity, the Reynolds and Nusselt numbers, heat transfer rate, and energy and exergy efficiencies. The evacuated tube heaters have a higher temperature compared to the collectors with a plane surface. Their thermal performance increases by using all-glass active circulation and heat pipe integration. The concentrative type of solar water heaters is superior to other solar heaters, particularly in achieving higher water temperatures. Their performance improves by using a rotating mirror concentrator. The integration of the system with energy storage components, phase change materials, or a heat pump provides a satisfactory performance over conventional solar water heaters.
Sonodynamic therapy (SDT) has considerably revolutionized the healthcare sector as a viable noninvasive therapeutic procedure. It employs a combination of low-intensity ultrasound and chemical entities, known as a sonosensitizer, to produce cytotoxic reactive oxygen species (ROS) for cancer and antimicrobial therapies. With nanotechnology, several unique nanoplatforms are introduced as a sonosensitizers, including, titanium-based nanomaterials, thanks to their high biocompatibility, catalytic efficiency, and customizable physicochemical features. Additionally, developing titanium-based sonosensitizers facilitates the integration of SDT with other treatment modalities (for example, chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, and immunotherapy), hence increasing overall therapeutic results. This review summarizes the most recent developments in cancer therapy and tissue engineering using titanium nanoplatforms mediated SDT. The synthesis strategies and biosafety aspects of Titanium-based nanoplatforms for SDT are also discussed. Finally, various challenges and prospects for its further development and potential clinical translation are highlighted. 相似文献
In this article, an islanded microgrid (MG) consisting of the diesel generator (DEG), the photovoltaic panel (PV), the wind turbine generator (WTG), the battery energy storage system (BESS), and the control unit is considered. In the islanded MGs, the control signals are exchanged on the open communication network, which results in the time delays in the input and the output of the islanded MG central controller (MGCC). The time delay has a destructive effect on the islanded MG stability. Thus, finding the maximum allowable time delay bound (MADB) is a significant issue. Since it is shown that the fractional order systems have larger stability region and more robustness rather than the corresponding integer order systems, in this research, we propose the fractional order proportional-integral-derivative (FOPID) controller as the MGCC to achieve a larger MADB value. As another innovation, in this article, a method is presented in which the MADB of the islanded MG system is determined considering the parametric uncertainties related to the damping coefficient (D) and the inertia constant (H). It is shown that the percentage improvement in the MADB of the uncertain MG system with the designed FOPID controller over the integer order proportional-integral-derivative (IOPID) controller is 9.64%. The accuracy of the proposed method is verified by simulation results in Matlab. 相似文献
Two azole-based Schiff bases, namely, 2-(((1H-1,2,4-triazol-3-yl)imino)methyl)-4-bromophenol, TIB , and 4-Bromo-2-((thiazol-2-ylimino)methyl)phenol, BTP , are synthesized and used as corrosion inhibitors for mild steel, MS, in acidic medium. The inhibitive effect of TIB and BTP , in 0.5 m hydrochloric acid, is investigated using weight loss, potentiodynamic polarization, and electrochemical impedance measurements. The optimum concentrations of TIB and BTP for coverage of metal surface are 600 and 400 μM, respectively. An electrochemical impedance study shows that the corrosion of MS is reduced through a charge transfer mechanism. The maximum inhibition efficiencies at optimum concentration of TIB and BTP are ≈83% and ≈81%, respectively. Tafel polarization reveals that the TIB and BTP behave as mixed-type inhibitors, predominantly of cathodic type. The results indicate that the MS surface has been blocked by TIB and BTP molecules following the Langmuir adsorption isotherm. The formed protective layer on MS surface is verified using SEM and EDX techniques. Furthermore, atomic force microscopic study reveals that the current inhibitors increase the surface smoothness of MS by adsorbing on the metallic surface. 相似文献
Research of Glycolaldehyde Formed During Gamma Irradiation of Maize Starch . During gamma irradiation of maize starch, glycolaldehyde occurs (5,6 μg/g/Mrad, in oxygen). The influence of several parameters has been determined: irradiation conditions (dose, temperature, surrounding gas), stockage temperature and starch characteristics (moisture, impurities). On the other hand, irradition effects were compared to heat treatment effects. 相似文献