Investigating ion-surface collisions with a niobium superconducting tunnel junction detector in a time-of-flight mass spectrometer

The performance of an energy sensitive, niobium superconducting tunnel junction detector is investigated by measuring the pulse height produced by impacting molecular and atomic ions at different kinetic energies. Ions are produced by laser resorption and matrix-assisted laser desorption in a time-of-flight mass spectrometer. Results show that the STJ detector pulse height decreases for increasing molecular ion mass, passes through a minimum at around 2000 Da, and the increases with increasing mass of molecular ions above 2000Da. The detector does not show a decline in sensitivity for high mass ions as is observed with microchannel plate ion detectors. These detector plus height measurements are discussed in terms of several physical mechanisms involved in an ion-surface collision

Линейный пробоотборник с щелевым отсекателем

Объектом исследования является влияние положения отсекателя относительно потока дробленой руды на характеристики линейного пробоотборника с щелевым отсекателем. Предметом исследования является конструктивные особенности линейного пробоотборника с щелевым отсекателем. Цель работы – разработка и исследование линейного пробоотборника с щелевым отсекателем для отбора проб из вертикального потока дробленой руды.The object of research is the influence of the position of the cutter relative to the flow of crushed ore to the characteristics of the linear slotted sampler. The subject of the research is design features in-line slotted sampler. The purpose of the work is the development and study of a linear sampler with slotted cutter for sampling from the vertical stream of crushed ore

NK cell receptor profiling of endometrial and decidual NK cells reveals pregnancy-induced adaptations

Natural killer (NK) cells, with a unique NK cell receptor phenotype, are abundantly present in the non-pregnant (endometrium) and pregnant (decidua) humanuterine mucosa. It is hypothesized that NK cells in the endometrium are precursors for decidual NK cells present during pregnancy. Microenvironmental changes can alter the phenotype of NK cells, but it is unclear whether decidual NK cell precursors in the endometrium alter their NK cell receptor repertoire under the influence of pregnancy. To examine whether decidual NK cell precursors reveal phenotypic modifications upon pregnancy, we immunophenotyped the NK cell receptor repertoire of both endometrial and early-pregnancy decidual NK cells using flow cytometry. We showed that NK cells in pre-pregnancy endometrium have a different phenotypic composition compared to NK cells in early-pregnancy decidua. The frequency of killer-immunoglobulin-like receptor (KIR expressing NK cells, especially KIR2DS1, KIR2DL2L3S2, and KIR2DL2S2 was significantly lower in decidua, while the frequency of NK cells expressing activating receptors NKG2D, NKp30, NKp46, and CD244 was significantly higher compared to endometrium. Furthermore, co-expression patterns showed a lower frequency of NK cells co-expressing KIR3DL1S1 and KIR2DL2L3S2 in decidua. Our results provide new insights into the adaptations in NK cell receptor repertoire composition that NK cells in the uterine mucosa undergo upon pregnancy

Rapid mass spectrometric DNA diagnostics for assessing microbial community activity during bioremediation. 1998 annual progress report

'Biological activity has often been attributed to changes in pollutant profiles found in contaminated soils when abiotic processes actually caused pollutant removal. Careful evaluation of bioremediation necessitates that all transformation and removal pathways are anticipated so that the pathways are controlled or monitored. The author''s work is directed at evaluating a monitoring strategy that relies on the combined use of DNA diagnostic procedures and mass spectrometry as the detection scheme. The intent is to track bioremediation by measuring the occurrence of genes in soil samples that are known to code for enzymes capable of degrading specific pollutants. Matrix-assisted-laser-desorption- ionization time-of-flight mass spectrometry (MALDI-TOF-MS) offers the possibility for automation and high throughput PNA detection as is needed to track the course of bioremediation over large polluted areas.