Determination of Brain Tissue Samples Storage Conditions for Reproducible Intraoperative Lipid Profiling

Ex-vivo molecular profiling has recently emerged as a promising method for intraoperative tissue identification, especially in neurosurgery. The short-term storage of resected samples at room temperature is proposed to have negligible influence on the lipid molecular profiles. However, a detailed investigation of short-term molecular profile stability is required to implement molecular profiling in a clinic. This study evaluates the effect of storage media, temperature, and washing solution to determine conditions that provide stable and reproducible molecular profiles, with the help of ambient ionization mass spectrometry using rat cerebral cortex as model brain tissue samples. Utilizing normal saline for sample storage and washing media shows a positive effect on the reproducibility of the spectra; however, the refrigeration shows a negligible effect on the spectral similarity. Thus, it was demonstrated that up to hour-long storage in normal saline, even at room temperature, ensures the acquisition of representative molecular profiles using ambient ionization mass spectrometry.     

Absolute size exclusion chromatography. Part 2. Calculation of molecular weight averages

An absolute method to obtain molecular weight averages is theoretically proved and experimentally applied to size exclusion chromatographic data. The method is based on stoichiometric relationships and uses labelled polymer molecules.     

A Compact Second-Harmonic Generator for Tasks of Precision Spectroscopy Within the Range of 240–600 nm

We develop a universal design of a second-harmonic generator enabling a high-efficiency conversion of the CW laser radiation to a range of 240–600 nm. The distinctive features of the generator are its compact size and high stability achieved using an all-in-one (monolithic) hermetic body frame, which enables applications of this device in a broad range of precision spectroscopy and laser cooling. We design three systems for radiation conversion to ranges of 280, 410, and 560 nm and present their characteristics. The systems are used for laser cooling of magnesium ions (280 nm) and thulium atoms (410 nm). Due to the conversion efficiency and stability, the second-harmonic generators developed surpass most commercially available systems of Western manufacturers.     

Influence of nonlinear effects on destruction of active elements of electron-beam-pumped lasers Based on ZnSe-containing quantum-size structures

The fracture patterns of active elements of pulsed green lasers with transverse electron-beam pumping, based on ZnSe-containing quantum-size structures, have been investigated. The fracture in the form of thin (～1 μm) and long (to 100–150 μm) filaments can be explained by the self-focusing of the intrinsic laser radiation in the semiconductor structure.     

Improvements for ground-based remote sensing of atmospheric aerosol properties by additional polarimetric measurements

We discuss the improvements in the aerosol properties characterization resulting from the additional multi-wavelength polarization measurements measured by a new CIMEL polarized sun/sky-photometer, CE318-DP. In order to process direct-sun, sky and polarization measurements in a wide spectral range (340–1640 nm), we developed new calibration methods and strategies, e.g. using the Langley plot method to calibrate both direct-sun irradiance and sky radiance, as well as combining laboratory facilities with a vicarious method to calibrate the polarized sky measurements. For studying the impact of new polarimetric measurements on the retrievals of aerosol properties, we have processed an extensive record of field measurements using an updated Dubovik and King retrieval algorithm [Dubovik O, Sinyuk A, Lapyonok T, Holben BN, Mishchenko MI, et al. Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust. J Geophys Res 2006;111:D11208.]. A preliminary analysis shows that adding polarization in the inversion can reduce possible errors (notably for about 30% of our field cases) in the fine mode size distribution, real part of refractive index and particle shape parameter retrievals, especially for small particles.     

Effect of gas pressure on amplitude and duration of electron beam current in a gas-filled diode

The parameters of an electron beam generated in helium in the pressure range p = 10⁻⁴−12 atm are studied. Nanosecond high-voltage pulses are applied to a gap between a tubular cathode and planar anode, which is made of 45-μm-thick AlBe foil. Behind the anode, an electron beam is detected at a helium pressure of 12 atm. The pressure dependence of the beam current amplitude shows three peaks at p ≈ 0.01, ≈ 0.07, and ≈ 3 atm. The beam-induced glow of a luminescent film placed behind the foil and the discharge glow at different helium pressures in the gas-filled diode are photographed.