Pyridazines. LXXV. Some Quaternary and Mesoionic s-Triazolo( 4,3-b)pyridazines

Quaternization of some s-triazolo(4,3-b)pyridazines, formation of a mesoionic derivative and some transformations of these compounds are described

One-pot synthesis and characterization of InP/ZnSe semiconductor nanocrystals

We report on the one-pot synthesis of InP/ZnSe quantum dots (QDs) using a precursor-based colloidal synthesis in a noncoordinating solvent environment. The structural and optical studies were carried out on the as-prepared InPQDs. The quantum yield of the nanocrystals was recorded as 6% and a 1.4 times reduction in the ratio of trap-related emission to band edge emission was observed on ZnSe passivation of the InPQDs.Web of Scienc

Effect of the Surface on the Electron Quantum Size Levels and Electron g-Factor in Spherical Semiconductor Nanocrystals

The structure of the electron quantum size levels in spherical nanocrystals is studied in the framework of an eight--band effective mass model at zero and weak magnetic fields. The effect of the nanocrystal surface is modeled through the boundary condition imposed on the envelope wave function at the surface. We show that the spin--orbit splitting of the valence band leads to the surface--induced spin--orbit splitting of the excited conduction band states and to the additional surface--induced magnetic moment for electrons in bare nanocrystals. This additional magnetic moment manifests itself in a nonzero surface contribution to the linear Zeeman splitting of all quantum size energy levels including the ground 1S electron state. The fitting of the size dependence of the ground state electron g factor in CdSe nanocrystals has allowed us to determine the appropriate surface parameter of the boundary conditions. The structure of the excited electron states is considered in the limits of weak and strong magnetic fields.Comment: 11 pages, 4 figures, submitted to Phys. Rev.

Long Wave Infrared Type II Superlattice Focal Plane Array Detector

The XBn/XBp family of barrier detectors enables diffusion limited dark currents comparable with HgxCd1-xTe Rule-07 and high quantum efficiencies. SCD’s XBp type II superlattice (T2SL) detector contains InAs/GaSb and InAs/AlSb T2SLs, and was designed for the long wave infrared (LWIR) atmospheric window using k · p based modeling of the energy bands and photo-response. Wafers are grown by molecular beam epitaxy and are fabricated into focal plane array (FPA) detectors using standard FPA processes, including wet and dry etching, indium bump hybridisation, under-fill, and back-side polishing. The 640 × 512 pixel, 15 μm pitch, detector goes by the name of ‘Pelican-D LW’ and exhibits a quantum efficiency of ~ 50 per cent with background limited performance at an operating temperature of 77 K. It has a cut-off wave length of ~ 9.5 μm, with a pixel operability of above 99 per cent. The detector gives a very stable image with a residual non uniformity of below 0.04 per cent over its useful dynamic range. A new digital read-out integrated circuit has been designed so that the complete detector closely follows the configuration of SCD’s MWIR Pelican-D detector

Databases for Data Mining

Naloga se ukvarja z iskanjem sinergij med orodji za podatkovno rudarjenje in sistemi za upravljanje podatkovnih baz (SUPB). Predstavljajmo si situacijo analitičnega problema nad podatki, ki jih je preveč za obdelavo izključno v glavnem pomnilniku in premalo, da bi motivirali postavitev podatkovnega skladišča ali porazdeljenega analitičnega sistema. Ciljno področje je torej en sam osebni računalnik, s katerim rešujemo probleme podatkovnega rudarjenja. Zanima nas, ali obstajajo orodja, ki omogočajo učinkovito obdelavo in pripravo takšne količine podatkov za nadaljnjo analizo. Naloga se nanaša predvsem na drugi in tretji korak CRISP-DM standardnega modela podatkovnega rudarjenja, torej na razumevanje in pripravo podatkov, ne pa toliko na samo podatkovno rudarjenje. Preučuje, kako s pomočjo funkcionalnosti SUPB in orodij za luščenje, transformiranje ter nalaganje (ETL) čim bolj učinkovito pripraviti podatke za uporabo v podatkovnem rudarjenju. Podatkom zmanjšamo obseg in jih pretvorimo v ustrezno obliko. Optimizirani podatki, ki ne vsebujejo podvojenih zapisov, tiskarskih napak in drugih neželenih lastnosti ter vsebujejo le tiste atribute, ki jih lahko uporabimo, pozitivno vplivajo na hitrost in natančnost podatkovnega rudarjenja. Cilj naloge je torej poiskati primerne načine (orodja oz. kombinacije orodij, metodologije) kako pridobiti relativno velike količine podatkov iz različnih virov in oblik, jih združiti in pretvoriti v obliko, ki jo lahko neposredno uporabimo za podatkovno rudarjenje, pri tem pa uporabljati SUPB in ETL orodja.This work is about looking for synergies between data mining tools and databa-se management systems (DBMS). Imagine a situation where we need to solve an analytical problem using data that are too large to be processed solely inside the main physical memory and at the same time too small to put data warehouse or distributed analytical system in place. The target area is therefore a single personal computer that is used to solve data mining problems. We are looking for tools that allows us to effectively process and prepare such quantity of data for further analysis. The main focus of this work is not on data mining itself but in particular on the second and third step of CRISP-DM process standard for data mining, that is data understanding and data preparation step. The question is how to use functionalities of various DBMS and ETL tools to prepare data as effectively as possible to use it in data mining. Unneeded data should be ignored and the remainder should be transformed into an appropriate form. Data mining execution time and accuracy should be improved when using optimized data that do not contain unneeded attributes, duplicate records, typos and other unwanted properties. The objective of this work is thus to find appropriate practical methods (tools or combinations of tools, methodologies) for collecting relatively large amounts of data from different sources and in different forms, joining them and transforming this data to a format that can be used directly in data mining algorithms by using DMBS and ETL tools