Schwarz lemma for driving point impedance functions and its circuit applications

In this paper, a boundary version of the Schwarz lemma is investigated for driving point impedance functions and its circuit applications. It is known that driving point impedance function, Z(s) = 1 + c_p(s − 1)^p + c_{p + 1}(s − 1)^{p + 1} + ..., p > 1, is an analytic function defined on the right half of the s-plane. Two theorems are presented using the modulus of the derivative of driving point impedance function, |Z′(0)|, by assuming the Z(s) function is also analytic at the boundary point s = 0 on the imaginary axis with . In the obtained inequalities, the value of the function at s = 1 and the derivatives with different orders have been used. Finally, the sharpness of the inequalities obtained in the presented theorems is proved. Simple LC circuits are obtained using the obtained driving point impedance functions.     

Chimeric ribonuclease as a source of human adapter protein for targeted drug delivery

Assembled modular complexes for targeted drug delivery can bebased on strong non-covalent interactions between a cargo modulecontaining an adapter protein and a docking tag fused to a targetingprotein. We have recently constructed a completely humanizedadapter/docking tag system based on interactions between 15amino acid (Hu-tag) and 110 amino acid (HuS) fragments of humanribonuclease I (RNase I). Although recombinant HuS can be expressedand refolded into a functionally active form, the purificationprocedure is cumbersome and expensive, and more importantly,it yields a significant proportion of improperly folded proteins.Here we describe engineering, high-yield expression, and purificationof a chimeric bovine/human RNase (BH-RNase) comprising 1–29N-terminal amino acids of bovine ribonuclease A and 30–127amino acids of human RNase I. Unlike RNase I, the chimeric BH-RNasecan be cleaved by either subtilisin or proteinase K betweenA20 and S21, providing a functionally active HuS. The HuS obtainedfrom chimeric BH-RNase differs from wild-type HuS by an N24Tsubstitution; therefore, we have reverted this substitutionby mutating N24 to T24 in BH-RNase. This BH-RNase mutant canalso be cleaved by subtilisin or proteinase K yielding wild-typeHuS. The affinity of HuS obtained from BH-RNase to Hu-tag isapproximately five times higher than that for recombinant HuS,reflecting a higher percentage of properly folded proteins. Received June 9, 2003; revised August 4, 2003; accepted August 28, 2003.     

Upconversion optical nanomaterials applied for photocatalysis and photovoltaics: Recent advances and perspectives

Upconversion (UC) lanthanide nanomaterials have attracted enormous attention in the last two decades thanks to their unique ability to convert low-energy infrared photons into high-energy photons. In this mini-review, we briefly discussed the recent achievements related to the direct utilization of UC optical nanomaterials for photocatalysis and photovoltaic applications. In particular, selected examples of UC-containing devices/nanocomposites with improved performance were covered. In addition, we outlined some challenges and future trends associated with the widespread usage of UC nanomaterials.     

Synthesis of Schiff base–containing benzoxazine derivatives

The excellent chemical and physical properties of benzoxazine resins and the functionality of Schiff bases were combined in one compound's structure, creating newly designed benzoxazine derivatives that can form complexes with metals. The new type of benzoxazine monomer was synthesized via the ring-closure reaction of formaldehyde, aniline, and three newly designed Schiff bases. The presence of the Schiff base in the molecular structure of these novel benzoxazine monomers enables them to trap metals as the functional compounds, like Cu, from a solution. Thermally initiated polymerization occurs at a lower temperature by the formation of intermolecular and intramolecular hydrogen bonds between imine, oxazine, Schiff base hydroxyl groups, and the newly generated hydroxyl groups. The thermal behavior of the bisbenzoxazine monomers was investigated with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry, and then they were cured at 120, 180, and 230°C. According to the magnetic susceptibility, FTIR, scanning electron microscopy with energy dispersive X-ray spectroscopy, TGA, and microwave plasma atomic emission spectroscopy results, it is shown that Cu(II) complexes of the compounds were also succesfully synthesized, and they proved to be successful in catching metal. This is due to the functionality of Schiff bases forming the metal complexation in the compounds. The poly(bisbenzoxazine)s also showed high limiting oxygen index (31–37), low ring-opening temperature (150–190°C), high char yield (35%–49%), and excellent thermal stability, due to the highly crosslinked nature of the polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47908.     

THERMAL AND MASS DIFFUSIVITY FROM DYNAMIC SINGLE PELLET EXPERIMENTS

The single-pellet moment techniques previously developed for the evaluation of effective diffusion coefficient and effective thermal conductivity of a porous solid are combined and a procedure is proposed for the simultaneous evaluation of these constants from a single set of pulse response experiments. It is shown that both temperature and concentration response curves can be measured from a single pulse of oxygen injected into hydrogen carrier gas flowing past a catalyst pellet. It is shown that the zeroth moment of the concentration response peaks are sufficient for finding the effective diffusivity while both zeroth and first order moments are required for thermal conductivity. Experiments conducted at 110^°C with a boehmite pellet of porosity 0.57 gave a thermal conductivity value of 3.6 x 10^-4 cal/cm ^°K s and an effective diffusivity (for H₂O) of 0.054 cm2/s. The adsorption equilibrium constant of H₂O was determined as ρ_pK = 24.5 from the first moment data. If sorption resistance to diffusion through the pellet is included in the diffusion coefficient, an apparent value of 0.0011 cm2/s would be obtained for D_eff. This result indicates the importance of separation of diffusion and sorption parameters in the analysis.     

Phosphonates Meet Metal−Organic Frameworks: Towards CO2 Adsorption

Here we report a new highly microporous zirconium phosphonate material synthesized under solvothemal conditions. The specific Brunauer-Emmett-Teller (BET) surface area of the “unconventional metal−organic framework” (UMOF) is measured to be ∼900 m²/g, after following an appropriate activation protocol. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) shows that the material bears a free −OH functionality on the phosphonate linker that may interact with CO₂. CO₂ adsorption isotherms were collected and a measured heat of adsorption of 31 kJ/mol was obtained. In addition, adsorption isotherms of CO₂, N₂, and CH₄ at 298 K combined with Ideal Adsorbed Solution Theory (IAST) show that the material can be expected to display high selectivities for uptake of CO₂ versus N₂ or CH₄.     

Petrochemicals from ethanol over a W-Si-based nanocomposite bidisperse solid acid catalyst

Very high ethylene selectivity values approaching 100% and very high ethanol conversion values approaching 85% were obtained in dehydration of ethanol over a new W-silicate-based nanocomposite catalyst having both meso and macropores and containing a W/Si atomic ratio of 0.85. Silicotungsticacid was successfully incorporated into the catalyst structure following a one-pot hydrothermal synthesis procedure. This catalyst is highly stable and does not loose activity in polar solvents and it has a sufficiently high surface area for catalytic applications. Calcination temperature of the catalyst was found to have a very significant effect on the catalyst structure and also on its catalytic performance in ethanol dehydration. Maximum selectivity of the second major reaction product diethylether was obtained as 0.7 at 200 °C, with the catalyst which was calcined at 400 °C. Very high ethylene and diethylether yield values obtained in this study at different reaction conditions are highly promising for the production of petrochemicals from ethanol.     

Acceptive Immunity: The Role of Fucosylated Glycans in Human Host–Microbiome Interactions

The growth in the number of chronic non-communicable diseases in the second half of the past century and in the first two decades of the new century is largely due to the disruption of the relationship between the human body and its symbiotic microbiota, and not pathogens. The interaction of the human immune system with symbionts is not accompanied by inflammation, but is a physiological norm. This is achieved via microbiota control by the immune system through a complex balance of pro-inflammatory and suppressive responses, and only a disturbance of this balance can trigger pathophysiological mechanisms. This review discusses the establishment of homeostatic relationships during immune system development and intestinal bacterial colonization through the interaction of milk glycans, mucins, and secretory immunoglobulins. In particular, the role of fucose and fucosylated glycans in the mechanism of interactions between host epithelial and immune cells is discussed.