A Source of Soft X-Rays Based on a Radial Magnetron Gun

A source of soft (the wavelength is 10–20 nm) X rays based on an electron gun operating at an accelerating voltage of 400 V at a current of 0.2 A is described. The radiation intensity obtained is 0.6 × 10^–4 W/sr.     

Two new "protected" oxyphors for biological oximetry: properties and application in tumor imaging

We report the synthesis, calibration, and examples of application of two new phosphorescent probes, Oxyphor R4 and Oxyphor G4, optimized specifically for in vivo oxygen imaging by phosphorescence quenching. These "protected" dendritic probes can operate in either albumin-rich (blood plasma) or albumin-free (interstitial space) environments at all physiological oxygen concentrations, from normoxic to deep hypoxic conditions. Oxyphors R4 and G4 are derived from phosphorescent Pd-meso-tetra-(3,5-dicarboxyphenyl)-porphyrin (PdP) or Pd-meso-tetra-(3,5-dicarboxyphenyl)-tetrabenzoporphyrin (PdTBP), respectively, and possess features common for protected dendritic probes, i.e., hydrophobic dendritic encapsulation of phosphorescent metalloporphyrins and hydrophilic PEGylated periphery. The new Oxyphors are highly soluble in aqueous environments and do not permeate biological membranes. The probes were calibrated under physiological conditions (pH 6.4-7.8) and temperatures (22-38 °C), showing high stability, reproducibility of signals, and lack of interactions with biological solutes. Oxyphor G4 was used to dynamically image intravascular and interstitial oxygenation in murine tumors in vivo. The physiological relevance of the measurements was demonstrated by dynamically recording changes in tissue oxygenation during application of anesthesia (isofluorane). These experiments revealed that changes in isofluorane concentration significantly affect tissue oxygenation.     

Fast pyrolysis of an ensemble of biomass particles in a fluidized bed

A combined approach to the modeling of fast pyrolysis of biomass particles in a fluidized bed has been used. We used models of different levels: two models of pyrolysis of a single particle — with lumped and distributed parameters — and a model of pyrolysis of an ensemble of biomass particles based on the continuum equations for the gas blown through the bed and the equations of motion for individual particles. We have determined optimal (in terms of the biofuel yield) temperatures of the process for various particle sizes of wood biomass and various values of its moisture.     

Acoustic cavitation and its effect on flow in polymers and filled systems

We have studied the phenomenon of acoustic cavitation under the action of volume ultrasonic oscillations on polymer melts and filled compositions. This phenomenon and the stress state of the material have been studied by means of a device for the visualization of flow in polarized light. It has been shown that the process of cavity formation in high-viscosity systems has a certain threshold and that the critical amplitude of oscillations depends on the duration of ultrasonics action. The effect of acoustic field on the melts of commercial polymers and filled compositions results in structural changes. In addition, a sharp increase of the melt flow is observed. Model experiments have shown that the size of particles and filler distribution can also be changed by utrasonic oscillation.