Laser ion mobility spectrometry in the detection of ultra-low quantities of explosives.

The paper presents the results of research and development of ion mobility spectrometer with laser ion sources for detecting ultra-low quantities of explosives in air. Particular attention is paid to the mechanisms of the formation of negative ions. It is shown that laser ionization with respect to ion mobility spectrometry provides an increase of sensitivity and selectivity of detection. The ion mobility spectra of the most common nitro explosives are investigated. The detection threshold for laser ion mobility spectrometer was reached at the level of 10-14 g/cm3 (for trinitrotoluene).

Optoelectronic Properties of Semiconductor Quantum Dot Solids for Photovoltaic Applications.

Quantum dot (QD) solids represent a new type of condensed matter drawing high fundamental and applied interest. Quantum confinement in individual QDs, combined with macroscopic scale whole materials, leads to novel exciton and charge transfer features that are particularly relevant to optoelectronic applications. This Perspective discusses the structure of semiconductor QD solids, optical and spectral properties, charge carrier transport, and photovoltaic applications. The distance between adjacent nanoparticles and surface ligands influences greatly electrostatic interactions between QDs and, hence, charge and energy transfer. It is almost inevitable that QD solids exhibit energetic disorder that bears many similarities to disordered organic semiconductors, with charge and exciton transport described by the multiple trapping model. QD solids are synthesized at low cost from colloidal solutions by casting, spraying, and printing. A judicious selection of a layer sequence involving QDs with different size, composition, and ligands can be used to harvest sunlight over a wide spectral range, leading to inexpensive and efficient photovoltaic devices.

[Prognostic value of renal resistance index in estimating the progression of chronic kidney disease].

AIM: To study a relationship between main renal and intraparenchymal renal arterial resistance indices (RIs) measured by Doppler ultrasonography and clinical and laboratory parameters and to determine their prognostic value in estimating the progression of chronic kidney disease (CKD). SUBJECTS AND METHODS: The investigation enrolled 53 CKD patients divided into groups: glomerular and interstitial diseases. Glomerular filtration rate (GFR) calculated using the CKD-EPI formula, proteinuria (PU) severity, kidney sizes, renal parenchyma thickness, parenchyma/collecting index, and main and intrarenal vessel RIs were determined at the first hospitalization. The mean follow-up was 14 ± 2.64 months. The rate of GFR decline was estimated at the rehospitalization. RESULTS: Main renal and intrarenal vessel RIs depend on patient age and pulse pressure. The RIs are associated with GFR and PU in the group of glomerular diseases and with kidney sizes and structure in that of interstitial diseases. The interlobar arterial RI is the most sensitive predictor for worsening renal function with a threshold of 0.65, which is comparable to the prognostic value of PU. CONCLUSION: The main renal and intrarenal vessel RIs may be considered as a predictor for worsening renal function.