Search results for "Mite"
showing 10 items of 795 documents
Vācbaltiešu nacionālās komitejas ietekme Latvijas politikā 1918.-1920.g.
2018
Bakalaura darbā tiek analizēta vācbaltiešu nacionālās komitejas ietekme Latvijas politikā laika posmā no 1918. – 1920. gadam. Šī pētījuma tēma ir aktuāla, jo tā savā izpētē ir bijusi ļoti politizēta. Vācbaltiešu nacionālā komiteja nebija viennozīmīga, kā arī tā piedzīvoja izmaiņas visā pētījumā aplūkotajā laika posmā un līdz ar to arī tās attiecības ar Latvijas valdību. Galvenais darba mērķis ir noskaidrot vācbaltiešu nacionālās komitejas un Latvijas valdības politisko mijiedarbību un nacionālās komitejas lomu Latvijas politikā 1918. – 1920.gadā. Darba izpildei izvirzītie uzdevumi ir aplūkot latviešu un vācbaltiešu sociāli politiskās domas izveidi un savstarpējo mijiedarbību. Analizēt galve…
Spectral Structures in Econometrics: Modern Techniques in Wavelet Analysis and Band Limited Estimation
2007
This thesis presents a number of innovative techniques that can be used in the analysis of econometric data sequences in which the underlying components can be identified by their spectral signatures. To present these techniques intelligibly requires the preparatory expositions of Fourier analysis and of the theory of linear filtering that are presented in Chapters 2 and 3. Amongst the techniques for extracting components from short non stationary sequences that are described in Chapter 3 is a variant of the Hodrick--Prescott filter with a smoothing parameter that varies locally. This enables us to extract from the data trends that incorporate a number of structural breaks. The inadequacy o…
Non-Dyadic Wavelet Analysis
2006
The conventional dyadic multiresolution analysis constructs a succession of frequency intervals in the form of $(\pi/2^j, \pi/2^{j-1});j = 1, 2, \ldots, n$ of which the bandwidths are halved repeatedly in the descent from high frequencies to low frequencies. Whereas this scheme provides an excellent framework for encoding and transmitting signals with a high degree of data compression, it is less appropriate to the purposes of statistical data analysis. This paper describes a non-dyadic mixed-radix wavelet analysis which allows the wave bands to be defined more flexibly than in the case of a conventional dyadic analysis. The wavelets that form the basis vectors for the wave bands are derive…
The Relevance of Kneading and Extrusion Parameters in the Manufacture of Active Porous Aluminas from Pseudoboehmites
1987
In order to study the effect-on crushing strength, attrition resistance, specific pore volume, and pore volume distribution of extrudates-of kneading and extrusion parameters in the manufacture of active porous aluminas, a commercial pseudoboehmite (Pural SB from Condea Chemie, Brunsbuttel, FRG) was employed. A minimum kneading torque was required to prepare an extrudable paste, predetermined by extrusion conditions. The torque had an upper limit with respect to certain extrudate properties. The amount of water and the concentration of nitric acid as binder solutions were found to have a decisive bearing on the mechanical properties and the distribution of the pore volume. Crushing strength…
Susceptibility of Seven Termite Species (Isoptera) to the Entomopathogenic Fungus Metarhizium anisopliae
2009
International audience; Seven termite species (Isoptera) from five families were tested for disease susceptibility against the entomopathogenic fungus Metarhizium anisopliae using a standard protocol: Mastotermes darwiniensis (Mastotermitidae), Hodotermopsis sjoestedti (termopsidae), Hodotermes mossambicus (Hodotermitidae), Kalotermes flavicollis (Kalotermitidae), Reticulitermes flavipes and Prorhinotermes canalifrons (Rhinotermitidae), and Nasutitermes voeltzkowi (termitidae). Our results showed a large diversity in disease susceptibility against M. anisopliae among the different species tested and we suggest that the evolution of disease resistance mechanisms in Isoptera may be influenced…
Enhancement of SOD activity in boehmite supported nanoreceptors
2018
The binuclear Cu2+ complex of a pyridinophane polyamine ligand ranking amongst the fastest SOD mimetics so far reported displays a remarkable SOD activity enhancement when grafted to the surface of boehmite (γ-AlO(OH)) nanoparticles (BNPs).
Improvement of boehmite nanoparticles' aqueous dispersability by controlling their size, shape and crystallinity
2014
In this work, results on the control of size, shape, crystallinity and aqueous dispersability of boehmite prepared by a hydrothermal process are reported. The two step synthetic procedure entailed the precipitation of a xerogel by adding NaOH until pH 10 to a solution of aluminum nitrate at 100 °C without or with additives such as tartaric acid and maltitol, and a subsequent hydrothermal treatment at 150 and 200 °C for different periods of time. The final materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and elemental analysis. The stability and other characteristics of the boehmite nanoparticle aqueous dispersions were determined by measuring t…
Naphthalene-containing polyamines supported in nanosized boehmite particles
2007
Boehmite nanoparticles with covalently linked polyamine chains functionalized with naphthalene fluorophores have been prepared and characterized. The characterization of the materials by elemental microanalysis, X-ray powder diffraction, MAS 29Si NMR and electron microscopy unambiguously prove that the covalent anchorage had occurred. Steady-state fluorescence emission studies show that the luminescent properties of the modified nanoparticles are sensitive to changes in concentration of hydrogen ions, metal ions and anionic nucleotides such as ATP. The behaviour of the attached materials in aqueous solution is parallel to the behaviour of the single fluorophoric polyamines. Comparisons are …
Tuning the size and shape of nano-boehmites by a free-additive hydrothermal method
2015
A synthetic procedure allowing the control of boehmite micro and nanoparticles is presented. The proposed hydrothermal synthetic procedure is based on the control of three reaction parameters, the pH and temperature of precipitation of xerogels and the water/xerogel ratio for the hydrothermal process, carried out at 200 °C for 48 h. Results obtained by measurements on transmission electron microscopy (TEM) images indicate that at pH 5 micro or nanorods of controlled length between ca. 300 and 50 nm were obtained depending on the temperature of precipitation of the xerogel (25 or 100 °C) and the water/xerogel ratio used (1/1, 6/1, 15/1). On the contrary, at pH 10, nanoplatelets with major ba…
Grafted squaramide monoamine nanoparticles as simple systems for sulfate recognition in pure water.
2012
New simple systems formed by a chain containing a squaramide function and a quaternised amine group attached to boehmite or silica-coated boehmite nanoparticles are able to discriminate anions in pure water.