Search results for "LOD"
showing 10 items of 4833 documents
Materiali ibridi a base di nanotubi di allosite per la rimozione d’inquinanti
2017
L’allosite (HNT) è un interessante materiale argilloso allumino-silicato naturale, non tossico e biocompatibile, con la caratteristica forma tubolare cava dotata di parziale carica positiva interna e negativa esterna.Combinando le peculiarità di un composto organico con le proprietà di un materiale inorganico, è possibile ottenere sistemi ibridi organici–inorganici con interessanti proprietà e vasti campi di applicazione. Sono un esempio delle “nanospugne” capaci di adsorbire efficacemente potenziali inquinanti. In questo contesto sono stati preparati, dei materiali ibridi “spugna” costituiti da unità ciclodestriniche e allosite e ancora un sistema ibrido HNT-Cucurbit[8]uril. Il primo possi…
Alūziju funkcijas Rodžera Zelaznija „Amberas hronikās”
2015
Bakalaura darba tēma ir ‘Alūziju funkcijas Rodžera Zelaznija Darbā Amberas Hronikas. Šajā amerikāņu autora fantāzijas romānu krājumā ietilpst divi stāstu cikli ‘Korvina cikls’ un ‘Merlina cikls’. Šī bakalaura darba pētījuma objekti ir ‘Korvina cikla’ pirmie divi romāni - ‘Deviņi Amberas prinči’ un ‘Avalonas ieroči’. Darba mērķis ir izpētīt alūziju funkcijas iepriekš minētajos darbos, lai sasniegtu izvirzīto mērķi tika pielietota kvalitatīvā kontentanalīze (jeb satur analīze). Alūziju funkcijas kuras tika sīkāk pētītas bija tās kuras ataino tēlu vai tēlus, tās kuras ataino vidi, tās kuras ataino atmosfēru, un tās kurās izraisa humoru. Pēc darba veikšanas tika secināts, ka funkcijas tika real…
Organized assemblies of magnetic clusters
2003
Abstract In this work we have explored the possibilities to create layered organizations of the Mn 12 single-molecule magnets using the Langmuir–Blodgett technique or attaching these clusters onto a metal surface by preparing self-assembled monolayers (SAMs). In the first part we discuss the use of the Langmuir–Blodgett (LB) technique in order to obtain organized magnetic films formed by monolayers of these clusters. Two strategies have been used with this aim. The first one consists of mixing Mn 12 acetate or benzoate derivatives with an amphiphile, while the second procedure is based on the use of Mn 12 derivatives specifically designed to form LB films. An alternative method is that of p…
Nemirstība kā ideāls Ge Hun daiļradē
2019
Maģistra darba tēma „Nemirstība kā ideāls Ge Hun darbos” veltīta domātāja un alķīmijas meistara Ge Hun (283.-343.) darbu izpētei un analīzei. Ge Hun, ko Rietumu sinologi raksturo kā izcilāko daoisma alķīmiķi, rakstnieku un mediķi, rakstiskā veidā fiksēja daoisma metodes nemirstības sasniegšanai un jaunības saglabāšanai, pēc kā tiecās ne tikai daoisma sekotāji, bet arī vienkāršie cilvēki. Viņš ir pazīstams gan kā vērtīgu alķīmijas tekstu autors, gan ir devis arī nenovērtējami lielu ieguldījumu ķīniešu tradicionālās medicīnas pētījumiem arī mūsdienās. Viņa teksti bija nozīmīgi akupunktūras un piededzināšanas teoriju bagātināšanā un veicināja šo tehniku attīstību. Šī darba mērķis ir izpētīt al…
On the formation of inclusion complexes at the solid/liquid interface of anchored temperature-responsive PNIPAAM diblock copolymers with γ-cyclodextr…
2017
The thermal responsive behavior of adsorbed layers of diblock copolymers of poly(N-isopropylacrylamide) (PNIPAAM) and poly((3-acrylamidopropyl)trimethylammonium chloride) (PAMPTMA(+)) with γ-cyclodextrin (γ-CD) at the solid/liquid interface has been investigated using three in situ techniques: null ellipsometry, quartz–crystal microbalance with dissipation monitoring, and neutron reflectometry. The measurements provided information about the adsorbed amounts, the layer thickness, hydration and viscoelastic properties, and the interfacial structure and composition. The copolymers adsorb to silica with the cationic PAMPTMA(+) blocks sitting as anchors in a flat conformation and the PNIPAAM ch…
Highly Sensitive Detection of Naphthalene in Solvent Vapor Using a Functionalized PBG Refractive Index Sensor
2012
We report an optical refractive index sensor system based on a planar Bragg grating which is functionalized by substituted γ-cyclodextrin to determine low concentrations of naphthalene in solvent vapor. The sensor system exhibits a quasi-instantaneous shift of the Bragg wavelength and is therefore capable for online detection. The overall shift of the Bragg wavelength reveals a linear relationship to the analyte concentration with a gradient of 12.5 ± 1.5 pm/ppm. Due to the spectral resolution and repeatability of the interrogation system, this corresponds to acquisition steps of 80 ppb. Taking into account the experimentally detected signal noise a minimum detection limit of 0.48 ± 0.05 pp…
Supramolecular Chemical Sensors Based on Pyrene Monomer-Excimer Dual Luminescence
2010
The past ten years have seen a spectacular development of chemical sensors based on the monomer-excimer dual luminescence of aromatic systems, such as pyrene. Either in the form of integrated or multicomponent molecular devices these chemosensors have been attracting a high interest above all because of their unique ratiometric properties. This review will focus on the latter systems, which can be classified into two classes: Firstly, the assembly of receptor-effector conjugates is triggerred by the analyte of interest. As a result, the sensor shows monomer to excimer fluorescence switching upon substrate binding. Secondly, the supramolecular assembly that constitutes the sensor is perturbe…
Comparison of the solid-phase extraction efficiency of a bounded and an included cyclodextrin-silica microporous composite for polycyclic aromatic hy…
2016
Solid-phase extraction is one of the most important techniques for sample purification and concentration. A wide variety of solid phases have been used for sample preparation over time. In this work, the efficiency of a new kind of solid-phase extraction adsorbent, which is a microporous material made from modified cyclodextrin bounded to a silica network, is evaluated through an analytical method which combines solid-phase extraction with high-performance liquid chromatography to determine polycyclic aromatic hydrocarbons in water samples. Several parameters that affected the analytes recovery, such as the amount of solid phase, the nature and volume of the eluent or the sample volume and …
Ultra high performance liquid chromatography-time-of-flight high resolution mass spectrometry in the analysis of hexabromocyclododecane diastereomers…
2014
An efficient ultra high performance liquid chromatography (UHPLC)-time-of-flight high resolution mass spectrometry (TOF-HRMS) method was elaborated for the determination of hexabromocyclododecane (HBCD) diastereomers in fish samples and compared against UHPLC-Orbitrap-HRMS and UHPLC-triple quadrupole (QqQ) tandem MS (MS/MS) techniques. The TOF-HRMS analyzer was operated at high resolution (>10000 full width at half maximum (FWHM)) with scanning the m/z range from 600 to 700, to achieve picogram quantitation limits. The effects of various operational parameters on the instrumental response were systematically investigated. Evaluation of the influence of sample clean-up procedure steps on sig…
Andu spāņu valodas Kolumbijā morfoloģiskās un leksiskās īpatnības sociālajos tīklos
2015
Šī darba mērķis ir noteikt andu spāņu valodas leksiskās un morfoloģiskās īpatnības, kā arī to statusu sociālajos tīklos, darba bāze ir Facebook, Twitter, Ask.fm un YouTube. Galvenie uzdevumu, lai sasniegtu šo mērķi: definēt andu spāņu valodu, raksturot interneta valodas īpatnības un, balstoties uz darbā apkopoto teoriju, analizēt andu spāņu valodu sociālajos tīklos. Nozīmīgākais šī darba secinājums ir, ka interneta valodas īpatnību dēļ kolumbiešu komunikācjā izzūd andu spāņu valodas varianta morfoloģiskās pazīmes, kā arī, saplūstot ar citiem spāņu valodas kolumbiešu variantiem, transformējas andu spāņu valodai raksturīgā leksika, tajā parādoties kolumbiešu žargoniem, slengam un vulgārismiem…