Resonance ionization spectroscopy for trace analysis and fundamental research

Resonance ionization spectroscopy (RIS) and its combination with mass spectrometry (RIMS) have grown to become powerful techniques, which offer high sensitivity as well as elemental and isotopic selectivity. The principles of RIS and RIMS are introduced; they primarily concern the analysis of the optical spectra for the choice of efficient excitation schemes and the suitable design of the experimental apparatus. Recent applications span from studies of short-lived isotopes at on-line mass separators to a wide variety of trace analysis applications for radioactive isotopes, which can range from measurements of solar neutrino flux to environmental assessment.On leave from Pacific Northwest Laboratory, Richland, USA     

Calibration of depth profiles of microparticles measured with plasma-based secondary neutral mass spectrometry

A gravimetric method is presented for the easy determination of sputter erosion rates for powders, applicable also to non-conducting materials. Measurements of the erosion rates of 22 powders gave an average value of 0.4 nm/s ±50% for bombardment with 400 eV Ar⁺ at 1 mA/cm². The validity of the data has been demonstrated with technical pigments and outdoor aerosol particles.     

ARXPS-analysis and morphology of sputtered nanocrystalline TiC/SiC coatings

ARXPS (angle resolved X-ray photoelectron spectroscopy) measurements are used to obtain informations about surfaces and grain boundaries. Data acquired from nanocrystalline carbidic hard coatings have been employed to establish structural models. Magnetron-sputtered coatings of TiC, SiC and TiC/SiC were examined. In such coatings, partly defective TiC nanocrystallites are surrounded by interfacial carbide. This excess carbon shows a binding state similar to that of doped graphite or fullerenes. X-ray amorphous SiC is found in the residue. On top of sputtered SiC coatings, less oxide and graphite is found as compared to TiC/SiC or TiC coatings.     

(NH4)2MoS4在活性炭上浸渍过程的研究:Ⅱ.干燥机理及模型

（ＮＨ＿４）＿２ＭｏＳ＿４在活性炭上浸渍过程的研究Ⅱ．干燥机理及模型秦慧芳，张成芳，陆岗，俞丰，朱子彬（华东理工大学无机化工研究所，上海２００２３７）２３７）关键词硫代钼酸铵，活性炭，干燥，钼分布，干燥模型负载型催化剂的活性组分在载体上的分布，受浸渍...     

Amending cultures of selenium-resistant bacteria with dimethyl selenone

A possible biological intermediate in the reduction and methylation of selenium oxyanions, dimethyl selenone, was synthesized, and the first experiments involving the amendment of selenium resistant bacterial cultures with this compound are reported. The amount of volatile, reduced selenium-containing species released from these cultures into the headspace is significantly more than that produced in analogous experiments involving sodium selenate amended cultures. Dimethyl selenone is reduced in the presence of dimethyl sulfide and dimethyl disulfide in a complex growth medium, trypticase soy broth with 0.1% nitrate. This reduction occurs whether or not the reduced sulfur compounds are biologically produced.     

Sums of Two Exact Powers

An asymptotic formula is obtained for the number of representations of an element of a finite field as a weighted sum of two prescribed powers of primitive elements. This generalises previous work on sums of primitive elements, including that relating to some conjectures of Golomb.     

完全可分的三元系TS(v,4)的支撑集

§ 1　 IntroductionA triple system of order v and indexλ,denoted by TS(v,λ) ,is a collection of3- ele-mentsubsets Aof a v- set X,so thatevery 2 - subsetof X appears in preciselyλ subsets of A.L etλ≥ 2 and (X,A) be a TS(v,λ) .If Acan be partitioned into t(≥ 2 ) parts A1,A2 ,...,Atsuch that each (X,Ai) is a TS(v,λi) for 1≤ i≤ t,then (X,A) is called de-composable.Otherwise it is indecomposable.If t=λ,λi=1for 1≤ i≤ t,the TS(v,λ) (X,A) is called completely decomposable.It …     

High temperature superconducting thin films for microwave filters

YBa₂Cu₃O_7-δ and Tl₂Ba₂CaCu₂O₈ thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate quality requirements and the relation of thin film morphology, microstructure with microwave surface resistance were discussed.     

EXISTENCE AND UNIQUENESS OF LIMIT CYCLE FOR A CLASS OF (2n+1)TH ORDER DIFFERENTIAL SYSTEM

In this paper we consider the problem ofllrmt cycles for thefollowing system【&一y＋6x＋a旷＋a。xy＋a。xy‘＋6xv‘”,(门)!i二 X( 一 by)．Ssstem(1)with k二 b二 0 was studiedin P叩er[1];Ifk 4 0 by transformation:y三 x;V二告;d,二 kdt,system(1)。二。can be trmslated Into the form studiedIn p。per IZ]三 System(1)With口1二 k二 0 W。S Studied ill paper k3]．Ifi System(1;SllPPOSe th。t:(1 ＞2 Is。11 lllteger,k / 0*d 6 / oi(2)。1。2 ＋。5 2 0,this assumption Is the same as that In paper[1];(3)w…     

基于TMS320C5410EVM板的IIR数字滤波器的设计

本文研究DSP中的IIR数字滤波器的原理和用MATLAB在TMS320C5410EVM中设计IIR数字滤波器的过程和设计方法以及程序的调试方法。