电感耦合等离子体原子发射光谱法测定钛酸钡纳米粉体中7种杂质元素

钛酸钡纳米粉体样品用盐酸溶解,在所得样品溶液中用电感耦合等离子体原子发射光谱法测定了以氧化物存在于样品中的7种杂质元素(包括镁、锶、钾、钠、铝、硅及铁),对测定的光谱条件进行了试验并优化达到上述各元素的测定上限为0.1%(质量分数).测得方法的检出限(3S/b)为(单位μg·L-1):2.0(铝),1.0(铁),20.0(钾),0.2(镁),4.0(钠),3.0(硅)及0.5(锶).应用此方法分析了两件实样,所得结果的相对标准偏差(n=6)小于等于2.0%,对其中4种杂质元素(镁、钾、钠和锶)同时用HG/T 3587-1999标准中的方法作分析校核,所得结果与此方法结果一致.     

Selectivity of Ammonium Acetate, Hydroxylamine Hydrochloride, and Oxalate/Ascorbic Acid Solutions for the Speciation of Fe, Mn, Zn, Cu, Ni, and Al in Early Tertiary Paleosols

Samples from early Tertiary subbasaltic and interbasaltic profiles were extracted by using a selective dissolution procedure. The specificity of each extracting solution for the different adsorption components was examined and the most important phases for the dispersion of Fe, Mn, Cu, Zn, Ni, and Al were identified. In order to observe an overall extraction pattern, the percentage of the total concentration extracted by each solution was recorded. The effectiveness of 1 M NH₂ OH · HCl/CH₃COOH solution for the dissolution of crystalline iron minerals was also examined by using an XRD technique. These results have particular importance for the use of tracer techniques to study iron mineral formation. Results from element speciation, rather than a total element procedure, provide increased detail of element dispersion and information on the choice of extraction solutions required for a more complete dissolution of these chemically weathered palaeosols.     

Characterizing Peptide Neutral Losses Induced by Negative Electron-Transfer Dissociation (NETD)

We implemented negative electron-transfer dissociation (NETD) on a hybrid ion trap/Orbitrap mass spectrometer to conduct ion/ion reactions using peptide anions and radical reagent cations. In addition to sequence-informative ladders of a•- and x-type fragment ions, NETD generated intense neutral loss peaks corresponding to the entire or partial side-chain cleavage from amino acids constituting a given peptide. Thus, a critical step towards the characterization of this recently introduced fragmentation technique is a systematic study of synthetic peptides to identify common neutral losses and preferential fragmentation pathways. Examining 46 synthetic peptides with high mass accuracy and high resolution analysis permitted facile determination of the chemical composition of each neutral loss. We identified 19 unique neutral losses from 14 amino acids and three modified amino acids, and assessed the specificity and sensitivity of each neutral loss using a database of 1542 confidently identified peptides generated from NETD shotgun experiments employing high-pH separations and negative electrospray ionization. As residue-specific neutral losses indicate the presence of certain amino acids, we determined that many neutral losses have potential diagnostic utility. We envision this catalogue of neutral losses being incorporated into database search algorithms to improve peptide identification specificity and to further advance characterization of the acidic proteome.     

E ∨-unitary covers for ∨-semilatticed inverse semigroups

It is well known that every inverse semigroup admits an E-unitary cover. In this paper we investigate the analogue of E-unitary covers within the variety of ∨-semilatticed inverse semigroups.     

Multiresolution Equivalence and Path Connectedness

An equivalence relation between multiresolution analyses was first introduced in 1996; an analogous definition for generalized multiresolution analyses was given in 2010. This article describes the relationship between the two notions and shows that both types of equivalence classes are path connected in an operator-theoretic sense. The GMRA paths are restricted to canonical GMRAs, and it is shown that whenever two MRAs in L ²(?) are equivalent, the GMRA path construction between their corresponding canonical GMRAs yields the natural analog of the MRA path. Examples are provided of GMRA paths that are distinct from MRA paths.