Search results for "Ultra"
showing 10 items of 4451 documents
Aktīvo farmaceitisko vielu degradācija ar maiņsprieguma aukstās plazmas avotiem
2019
Aktīvo farmaceitisko vielu degradācija ar maiņsprieguma aukstās plazmas avotiem. Zinātniskais vadītājs: Dr. ķīm., asoc. prof. Pēteris Mekšs, maģistra darbs, 69 lappuses, 28 tabulas, 37 attēli, 61 literatūras avoti, 12 pielikumi. Latviešu valodā. Darba gaitā ir apskatīti dažādu savienojumu degradācijas veidi, izmantojot brīvo radikāļu iegūšanu ar fizikālas iedarbības metodēm. Uzmanība pievērsta dažādiem elektriskās izlādes veidiem, to īpašībām un raksturlielumiem. Salīdzināti tādi izlādes veidi, kā barjerizlāde, koronizlāde, strīmera un dažādu temperatūru izlādes. Aprakstīta augstsprieguma avotu uzbūve un to darbības principi. Eksperimentālajā daļā aprakstīta un izvērtēta dažādu modeļsavieno…
Ultrasound-Guided Infraclavicular Axillary Vein Versus Internal Jugular Vein Cannulation in Critically Ill Mechanically Ventilated Patients: A Random…
2022
OBJECTIVES: This clinical trial aimed to compare the ultrasound-guided in-plane infraclavicular cannulation of the axillary vein (AXV) and the ultrasound-guided out-of-plane cannulation of the internal jugular vein (IJV). DESIGN: A prospective, single-blinded, open label, parallel-group, randomized trial. SETTING: Two university-affiliated ICUs in Poland (Opole and Lublin). PATIENTS: Mechanically ventilated intensive care patients with clinical indications for central venous line placement. INTERVENTIONS: Patients were randomly assigned into two groups: the IJV group (n = 304) and AXV group (n = 306). The primary outcome was to compare the IJV group and AXV group through the venipuncture an…
Specific distribution of cross-sectional area in each hamstring muscle of sprint runners and relationship between those and sprint performance
2018
The purpose of the present study was to examine characteristics of muscle anatomical cross-sectional area (CSA) for different regions from proximal to distal parts of each muscle of the hamstring muscles in high-level sprinters, and to examine the relationship with those and the sprint performance. The CSA of the semitendinosus (ST), semimembranosus (SM), biceps femoris long head (BFL) and biceps femoris short head (BFS) at the four different region of hamstring muscles for twenty sprinters (SPRINT) and twenty healthy male control subjects (CTRL) were measured by using B-mode ultrasonography. The measured regions were divided into four parts from proximal to distal parts (PRO1, PRO2, DIS2, …
Ultrasound accelerated esterification of bile acids
2004
In this study power ultrasound accelerated esterification reactions of some model substances and bile acids were done. In the model reactions the best result was 19-fold increase in the reaction rate when using ultrasound and the temperature was allowed to rise during the irradiation. In the case of bile acid methyl esters a clear increase in the reaction rates was also observed by ultrasonic irradiations.
Molecular Signatures of Biogeochemical Transformations in Dissolved Organic Matter from Ten World Rivers
2016
Rivers carry large amounts of dissolved organic matter (DOM) to the oceans thereby connecting terrestrial and marine element cycles. Photo-degradation in conjunction with microbial turnover is considered a major pathway by which terrigenous DOM is decomposed. To reveal globally relevant patterns behind this process, we performed photo-degradation experiments and year-long bio-assays on DOM from ten of the largest world rivers that collectively account for more than one-third of the fresh water discharge to the global ocean. We furthermore tested the hypothesis that the terrigenous component in deep-sea DOM may be far higher than biomarker studies suggest, because of the selective photochemi…
Do Tengmalm's owls see vole scent marks visible in ultraviolet light?
1997
Scent markings (urine and faeces) of small mammals are visible in ultraviolet (UV) light. Diurnal kestrels, Falco tinnunculususe them as a cue to find areas of food abundance. We studied whether vole-eating, nocturnal Tengmalm's owls, Aegolius funereuscan see vole scent marks using UV-vision. In a laboratory experiment, 14 young (less than 6 months old) and 14 adult (more than 6 months old) owls were individually given a choice between four adjacent arenas: (1) an arena with vole urine and faeces in UV light; (2) an arena with vole urine and faeces in visible light; (3) a clean arena in UV light; and (4) a clean arena in visible light. Owls did not prefer any of the four arenas. Our results…
Stability and extraction of bioactive sulfur compounds from Allium genus processed by traditional and innovative technologies
2017
Abstract Since ancient times, species from the Allium genus have been used in both culinary and medicinal applications. The health promoting properties, with well documented “evidence-based” studies, were attributed to the genus’ high content of bioactive organosulfur compounds. For these reasons, the organosulfur compounds have attracted interest in both food and pharmaceutical industries to be used as additives or supplements. Therefore, improvement in the extraction and stability during processing and storage of these molecules is crucial. The presented review documents the effects of traditional and innovative processing techniques on the extraction and stability of organosulfur compoun…
Excitation energy transfer in isolated chlorosomes from Chloroflexus aurantiacus
2009
Abstract Chlorosomes from green photosynthetic bacteria Chloroflexus aurantiacus have been studied by time-resolved femtosecond transient absorption spectroscopy. The fastest kinetics of 200–300 fs resolved, was interpreted to stem for intra-chlorosomal excitation energy transfer. Energy transfer from the antenna to the baseplate appeared as a major 9.2 ps rise component detected at the baseplate probe wavelength. Excitation energy transfer rates were evaluated for a model chlorosome. Calculated rod to rod, and rods to baseplate rate constants of 200–400 fs and 10–20 ps, respectively, are in accord with the experimental results.
Excitation Energy Transfer in Isolated Chlorosomes from Chlorobaculum tepidum and Prosthecochloris aestuarii
2012
Excitation energy transfer in chlorosomes from photosynthetic green sulfur bacteria, Chlorobaculum (Cba.) tepidum and Prosthecochloris (Pst.) aestuarii, have been studied at room temperature by time-resolved femtosecond transient absorption spectroscopy. Bleach rise times from 117 to 270 fs resolved for both chlorosomes reflect extremely efficient intrachlorosomal energy transfer. Bleach relaxation times, from 1 to 3 ps and 25 to 35 ps, probed at 758 nm were tentatively assigned to intrachlorosomal energy transfer based on amplitude changes of the global fits and model calculations. The anisotropy decay constant of about 1 ps resolved at 807 nm probe wavelength for the chlorosomes from Chlo…
The complex life-cycle of a polymorphic prokaryote epibiont of the photosynthetic bacterium Chromatium weissei
1993
In natural populations of the anaerobic phototrophic bacterium Chromatium weissei, many cells support a prokaryotic epibiont. This epibiont appears in several forms, all from the life cycle of a single species. A typical epibiont consists of one to five flattened coccoid cells stacked one above the other, perpendicular to the C. weissei surface. The cells at the proximal and distal ends of the stack are 0.6 μm in diameter and 0.8 μm in length; mid-stack cells are slightly shorter. A typical three or four cell stack is 2 μm in length. Small mesosome-like inclusions in the distal cell are involved in the development of ‘droplet’ shaped cells which are released from the end of each stack. Thes…