Increase in the average radiation power of a plasma relativistic microwave generator

The operation of a pulse-periodic plasma relativistic microwave generator with a pulsed power of 50 MW was experimentally studied. A change in the shapes of the electron collector and output unit allowed a significant increase in the average emission power. The microwave pulse duration was increased from 30 to 70 ns, and the repetition rate of microwave pulses was increased from 5 to 50 Hz.     

Pressure-induced order transition in nanodot-forming diblock copolymers at the air/water interface

Understanding and controlling the processes in block copolymer (BC) monolayers at the air/water interface during surface area compression is a key issue for producing ultrathin films of predetermined morphology with well-defined order and known dimensions. Langmuir isotherms of nanodot-forming BC monolayers generally display a plateau indicative of a 2D phase transition, which has been the subject of various interpretations in the literature. Here, based on investigations of Langmuir-Blodgett and Langmuir-Schaefer nanodot films of PS-P4VP mixed with 3-n-pentadecylphenol (PDP), we show by atomic force microscopy (AFM) that it involves a change in nanodot packing order (from quasi-hexagonal to quasi-square), argued to be a general phenomenon for nanodot BC monolayers. It is accompanied by system-specific conformational changes (as discussed in previous literature), which, in the present case, implicate PDP alkyl chain ordering, as deduced previously from in situ infrared data and indirectly supported here by AFM imaging.     

Forced axisymmetric vibrations of a hollow piezoceramic sphere with an electrical method of excitation

International Applied Mechanics -     

Surface characterization and direct electrochemistry of redox copper centers of bilirubin oxidase from fungi Myrothecium verrucaria

The key characteristics of multicopper oxidases are redox potentials of Type 1, Type 2 and Type 3 copper centers of enzymes. However, there is still a challenge to obtain a value of the redox "signature" of the enzymes. In this study, the electrochemical behavior of T1 and T2/T3 redox copper centers of bilirubin oxidase (BOD) from the fungi Myrothecium verrucaria was studied based on direct bioelectrocatalysis. Two distinct redox peaks corresponding to reduction and oxidation of T1 and T2/T3 redox centers of enzymes have been clearly detected in anaerobic conditions. The bioelectrocatalytic activity of the enzyme was studied in the presence of oxygen and redox mediators. The electron-transfer rate constant for BOD immobilized on carbon electrode (CE) is 1.5 s(-1). The mechanism of enzyme inactivation by ABTS has been proposed. The physical architecture of BOD layers immobilized on the electrode surface, including elemental and chemical composition, relative thickness and assembly of layers was investigated by Angle Resolved X-ray photoelectron spectroscopy. Unique peaks of BOD at 288.5 eV and of CE at 284.6 eV were used in a substrate over layer model for estimation of the thickness of the of BOD film on the carbon electrode surface.     

On the development of plasma relativistic microwave oscillator without strong magnetic field

A method for generating microwave pulses with a power of ～1 GW and a frequency controlled in a band from 2 to 15 GHz during the interaction of relativistic electrons with plasma without strong magnetic field is proposed in the numerical model. The combination of a broadband plasma relativistic microwave oscillator and a monochromatic magnetically insulated transmission line oscillator (MILO) allows the development of a device combining advantages of both prototypes.     

Solitonic-like excitations in cations of linear conjugated systems

Monatshefte für Chemie - Chemical Monthly - A quantum-chemical study of the atomic charges and bond orders in the cations of the linear conjugated systems was performed. It is shown that total...     

Axisymmetric waves in layered hollow cylinders with axially polarized piezoceramic layers

The propagation of axisymmetric waves in layered hollow cylinders with axially polarized layers is studied. Use is made of an efficient numerical analytic method. The original problem of electroelasticity for partial differential equations is reduced to a boundary-value eigenvalue problem for ordinary differential equations by representing the components of the stress tensor, displacement vectors, electric-flux density, and electric potential as waves traveling in the axial direction. The problem is solved with the stable discrete-orthogonalization method in combination with incremental search. Results of a numerical analysis of the dispersion equations over a wide range of geometrical characteristics of the cylinders are presented     

Torsional vibrations of piezoceramic hollow cylinders with circular polarization

A problem of natural torsional vibrations of hollow piezoceramic cylinders is considered. The piezoceramic is polarized in the circular direction. The lateral surfaces of the cylinder are covered with shortcircuited thin electrodes. The method of solution of the problem is based on the combination of the spline collocation methods along the longitudinal coordinate and the stepwise search method along the radial coordinate. We present results of a numerical analysis of a cylinder made from PZT 4 ceramic in a wide range of change in the geometrical characteristics of the cylinder.     

Pathways for Oral and Rectal Delivery of Gold Nanoparticles (1.7 nm) and Gold Nanoclusters into the Colon: Enteric-Coated Capsules and Suppositories

Two ways to deliver ultrasmall gold nanoparticles and gold-bovine serum albumin (BSA) nanoclusters to the colon were developed. First, oral administration is possible by incorporation into gelatin capsules that were coated with an enteric polymer. These permit the transfer across the stomach whose acidic environment damages many drugs. The enteric coating dissolves due to the neutral pH of the colon and releases the capsule’s cargo. Second, rectal administration is possible by incorporation into hard-fat suppositories that melt in the colon and then release the nanocarriers. The feasibility of the two concepts was demonstrated by in-vitro release studies and cell culture studies that showed the easy redispersibility after dissolution of the respective transport system. This clears a pathway for therapeutic applications of drug-loaded nanoparticles to address colon diseases, such as chronic inflammation and cancer.