Search results for "PMA"
showing 10 items of 118 documents
Relativistic scattering theory of charged spinless particles
1986
In the context of a relativistic quantum mechanics we discuss the scattering of two and three charged spinless particles. The corresponding transition operators are shown to satisfy four-dimensional Lippmann-Schwinger and eight-dimensional Faddeev-type equations, respectively. A simplified model of two particles with Coulomb interaction can be solved exactly. We calculate: (i) The partial waveS-matrix from which we extract the bound state spectrum. The latter agrees with a fourth-order result of Schwinger, (ii) The full scattering amplitude which in the weakfield limit coincides with the expression derived by Fried et al. from eikonalized QED.
Ship Roll Motion under Stochastic Agencies Using Path Integral Method
2009
The response of ship roll oscillation under random ice impulsive loads modeled by Poisson arrival process is very important in studying the safety of ships navigation in cold regions. Under both external and parametric random excitations the evolution of the probability density function of roll motion is evaluated using the path integral (PI) approach. The PI method relies on the Chapman-Kolmogorov equation, which governs the response transition probability density functions at two close intervals of time. Once the response probability density function at an early close time is specified, its value at later close time can be evaluated. The PI method is first demonstrated via simple dynamica…
Pentafluorophenyl Ester-based Polymersomes as Nanosized Drug-Delivery Vehicles
2015
In this work, activated ester chemistry is employed to synthesize biocompatible and readily functionalizable polymersomes. Via aminolysis of pentafluorophenyl methacrylate-based precursor polymers, an N-(2-hydroxypropyl) methacrylamide (HPMA)-analog hydrophilic block is obtained. The precursor polymers can be versatile functionalized by simple addition of suitable primary amines during aminolysis as demonstrated using a fluorescent dye. Vesicle formation is proven by cryoTEM and light scattering. High encapsulation efficiencies for hydrophilic cargo like siRNA are achieved using dual centrifugation and safe encapsulation is demonstrated by gel electrophoresis. In vitro studies reveal low cy…
Alma Mater: 2014/ Vasara
2014
Andra Čudare. Studentu taisnības bruņinieks Kirils Solovjovs -- Katrīna Žukova. Zinību lauks – atmiņu laiks -- LU māju noslēpumi atklājās Muzeju naktī -- LU Preses centrs. Zinātne – tas ir forši un radoši -- Sarmīte Rutkovska. Futbols kā tikšanās vieta -- LU Zinātnes un tehnikas vēstures muzejs, LU Preses centrs. Fotostāsts. Studentu mode cauri laikiem -- Laine Dobulāne. Atjauno modernākās ērģeles Latvijā -- LU Preses centrs. Praktiķi dalās pieredzē ar topošajiem kolēģiem -- LU Preses centrs. Reportāža. Psihiskas performances un «Ātrā palīdzība» jauno grupu konkursā «Hadrons» -- LU Bibliotēka. Ciparojot šodienai un nākotnei: LU Bibliotēkas pieredze digitalizācijā -- Kārlis Dārznieks. Jau 85…
Fast field cycling NMR relaxometry characterization of biochars obtained from an industrial thermochemical process
2012
Biochar has unique properties which make it a powerful tool to increase soil fertility and to contribute to the decrease of the amount of atmospheric carbon dioxide through the mechanisms of C sequestration in soils. Chemical and physical biochar characteristics depend upon the technique used for its production and the biomass nature. For this reason, biochar characterization is very important in order to address its use either for agricultural or environmental purposes. Three different biochars obtained from an industrial gasification process were selected in order to establish their chemical and physical peculiarities for a possible use in agronomical practices. They were obtained by char…
Solid State NMR characterization of the waterlogged wooden part of Acqualadrone roman rostrum
2011
Alma Mater: 2014/ Pavasaris
2014
Andra Čudare. Studentu students Rūta Mājeniece -- Studiju prakse - piedzīvo grāmatās rakstīto -- Lauma Abramoviča. Inta Brūna: cilvēks var padarīt ļoti daudz, ja vēlas -- LU Preses centrs. Prezentē jaunās Zobārstniecības mācību klīnikas telpas un programmu -- LU Preses centrs. Latvijas Universitāte Eiropas kultūras kontekstā -- Katrīna Žukova. LU dienesta romāni un mīlas stāsti -- Grācija Tafuni. Nevīžība un precizitāte: vienas medaļas divas puses -- Santa Margēviča. Klase aizraujošām mācībām -- LU Preses centrs. Pasniegtas ikgadējās Latvijas Universitātes Gada balvas -- Kristaps Gustsons. Latvijas Universitātes studente Soču olimpiskajās spēlēs -- Laine Dobulāne. LU Fonda stipendijas – amb…
Dabīgo un modificēto mālu sorbtīvās īpašības
2017
Dabīgo un modificēto mālu sorbtīvās īpašības. Batarāga A. Zinātniskā vadītāja Mg. ķīm. Karasa J. Bakalaura darbs. 54 lappuses, 15 attēli, 15 tabulas, 24 literatūras avoti, 1 pielikums. Latviešu valodā. Darbā ir noteikta katjonu apmaiņas kapacitāte (CEC- cation exchange capacity) četriem mālu paraugiem: izejas Saltišķu karjera māliem, bagātinātiem, atdzelžotiem karjera māliem un references materiālam SWy-2. Noteikšana veikta ar dažādām tehnikām- vara(II) etilēndiamīna un amonija acetāta noteikšanas metodēm. Ar vara(II) etilēndiamīna metodi noteikšanā ir izmantotas divas pieejas: fotometriska un titrimetriska detektēšana. Amonija acetāta metodes gadījumā CEC noteikšanai ir izmantota jonometri…
Osmozes parādība sulfonēta poliēterēterketona un cirkonija dioksīda kompozīta membrānās KHCO3 šķīdumā
2020
Darba ietvaros ir veikta PĒĒK sulfonēšana, SPĒĒK un SPĒĒK – ZrO2 kompozītmembrānu ieguve. Tika izpētīts osmozes ātrums KHCO3 šķīdumā caur Nafion un iegūtajam membrānām, kā arī SPĒĒK – ZrO2 kompozītmembrānu ZrO2 satura ietekme uz osmozes ātrumu.
Solid state nuclear magnetic resonance spectroscopy as a tool to characterize natural organic matter and soil samples. The basic principles
2007
Basic principles of solid state nuclear magnetic resonance spectroscopy (SS-NMR) are presented here. This paper is not pretending to provide an exhaustive treatment of the basics of SS-NMR. However, it will give an overview of the main applications in the characterization of environmental systems and will describe the problems related to the acquisition of quantitative solid state NMR spectra.