Direct <Emphasis Type="SmallCaps">d</Emphasis>-Glucose Oxidation over Noble Metal Nanoparticles Introduced on Polymer and Inorganic Supports

In the present work, nanocatalysts prepared on inorganic supports (zeolites) were investigated in d-glucose oxidation and compared to systems supported on polymer (hypercrosslinked polystyrene (HPS)) previously described. Catalytic activities and selectivities were measured under various reaction conditions. The selectivity of d-glucose oxidation and activity of both Pd-containing zeolites and HPS-Ru were similar (99.7% and TOF 0.013–0.014 mol/(mol Me s)). Physicochemical analysis X-ray photoelectron spectroscopy, liquid nitrogen physisorption, diffuse reflectance infrared Fourier transform spectroscopy of adsorbed CO for metal sites evaluation, CD₃CN for acid sites evaluation showed that Pd species were in oxidic form, while Ru species were in oxidic and reduced form. The catalytic activity decreased when acidic sites were present in Pd-containing zeolites.     

Two-port noise figure optimization of source-degenerated cascode CMOS LNAs

This paper presents a noise figure optimization technique for source-degenerated cascode CMOS LNAs with lossy gate inductors. The optimization technique, based on two-port theory, takes into account second order parasitic components. The effect of inductive source degeneration on LNA noise parameters is discussed. Measured noise figures agree well with the simulations confirming the accuracy of the noise model and allowing us to investigate the contributions of various components to the overall noise figure. A 0.18-μm CMOS LNA with an integrated inductor (Q = 7.5) achieves a noise figure of 1.16 dB and a return loss of 20 dB at 1.4 GHz, drawing 39 mA from a 1.8-V voltage supply, having gain (S ₂₁) of 14.5 dB, input P1dB of ?17.5 dBm, and input IP3 of ?13 dBm. LNAs with external inductors having quality factor of Q = 170 and Q = 40 achieve noise figures of 0.65 dB and 0.68 dB and a return loss of 20 dB at 1.4 GHz, drawing 37 mA from a 1.8-V voltage supply, having gain (S ₂₁) of 17 dB, input P1dB of ?22 dBm, and input IP3 of ?14 dBm. The large power consumption of the presented designs was intentionally selected in order to reduce the noise figure, an acceptable trade-off for LNA’s targeted for radio telescope applications, and to assess the impact of the large currents flowing through interconnect metals on the noise figure     

When is it reasonable to implement the discontinuous sliding‐mode controllers instead of the continuous ones? Frequency domain criteria

Professor Utkin proposed an example showing that the amplitude of chattering caused by the presence of parasitic dynamics (stable actuators) in some systems governed by the First‐Order Sliding‐Mode Controller is lower than that produced by the Super‐Twisting Algorithm. This example served to motivate this paper reconsidering the problem of comparison of chattering in systems with stable actuators, and driven by Discontinuous Sliding‐Mode Controllers (DSMCs) and Continuous Sliding‐Mode Controllers (CSMCs). Comparison of chattering produced by DSMC and CSMC taking into account their amplitudes, frequencies, and average power (AP) needed to maintain the system into real‐sliding modes, allowing to conclude the following: (i) for systems with slow actuators, the amplitude of oscillations and AP produced by DSMC be smaller than those caused by CSMC; (ii) for bounded disturbances with fixed Lipschitz constant, there exist sufficiently fast actuators for which the amplitude of oscillations and AP produced by CSMC be smaller than those caused by DSMC.     

Genetically Encoded FRET-Sensor Based on Terbium Chelate and Red Fluorescent Protein for Detection of Caspase-3 Activity

This article describes the genetically encoded caspase-3 FRET-sensor based on the terbium-binding peptide, cleavable linker with caspase-3 recognition site, and red fluorescent protein TagRFP. The engineered construction performs two induction-resonance energy transfer processes: from tryptophan of the terbium-binding peptide to Tb³⁺ and from sensitized Tb³⁺ to acceptor—the chromophore of TagRFP. Long-lived terbium-sensitized emission (microseconds), pulse excitation source, and time-resolved detection were utilized to eliminate directly excited TagRFP fluorescence and background cellular autofluorescence, which lasts a fraction of nanosecond, and thus to improve sensitivity of analyses. Furthermore the technique facilitates selective detection of fluorescence, induced by uncleaved acceptor emission. For the first time it was shown that fluorescence resonance energy transfer between sensitized terbium and TagRFP in the engineered construction can be studied via detection of microsecond TagRFP fluorescence intensities. The lifetime and distance distribution between donor and acceptor were calculated using molecular dynamics simulation. Using this data, quantum yield of terbium ions with binding peptide was estimated.     

Finite frequency H∞ control of singularly perturbed Euler‐Lagrange systems: An artificial delay approach

In this paper, we show that small artificial delays in the feedback loops operating in different time scales may stabilize singularly perturbed systems (SPSs). An artificial delay approach is proposed for the robust stabilization and L₂‐gain analysis of SPSs in the finite frequency domain. A two‐time‐scale delayed static output feedback controller is designed, in which the controller gains are formulated via a linear matrix inequality (LMI) algorithm. A distinctive feature of the proposed algorithm is setting controller parameters as free variables, which increases the degrees of freedom in controller design and leads to more flexibility in solving LMIs. Moreover, the proposed method is further extended to analyze the finite frequency system specifications of SPSs. The L₂‐gain performance analysis is conducted for parameter‐independent subsystems in their dominant frequency ranges, and the disturbance attenuation level of the original high‐order system is then estimated. Finally, the efficiency of the proposed design method is verified in an active suspension system subject to multiple finite frequency disturbance.     

Computational study of the effect of core–skin structure on the mechanical properties of carbon nanofibers

Journal of Materials Science - The effect of the core–skin structure on the mechanical properties of carbon nanofibers is investigated in large-scale molecular dynamics simulations of tensile...     

Investigation of Ionospheric Electron Density Change During Two Partial Solar Eclipses and Its Comparison with Predictions of NeQuick 2 and IRI-2016 Models

Wireless Personal Communications - In the present study, the results obtained by incoherent scatter radar (ISR) and empirical models (NeQuick2 and IRI-2016) of the variations in mid-latitude...     

Production of high porosity nanoparticles of cerium oxide in clay

Cerium oxide nanoparticles modified montmorillonite was obtained by interaction of a clay with (NH₄)₂Ce(NO₃)₆. The mean size of cerium oxide nanoparticles in clay was at 3.5 nm. The product was an amorphous solid and showed high permanent porosity and stability at high temperatures. The amorphous structure of the sample was proven by X-ray diffraction and electronic diffraction. The porous structure was studied by means of chemisorption and it was shown that samples calcined at 550 °C had S_BET = 239 m²/g; micropore volume = 0.1839 cm³/g; average pore diameter = 3.07 nm.