Contamination caused by ion-exchange resin!? Consequences for ultra-trace analysis

Well known sources of contamination are the laboratory environment, vessels, reagents and handling of the sample. Attention is drawn to the importance of cationic impurities included in the ion-exchangers used for trace-matrix separations (TMS) at the sub-ng/g-level. The usual rinsing and conditioning of the resins does not remove all adhering metals and thus leads to contaminated eluates in analytical work. High and badly reproducible blanks are observed, in particular for Na, Mg, Al, K, Cr, Fe, Zn and Ba. They are introduced during the polymerization process and are not ionically bound but obviously included in the polymer matrix. Any time when another “nest” of inclusion is opened in the resin column by mechanical stress, the next irreproducible event of contamination occurs.     

Nuclear magnetic resonance of175Hf oriented in iron

Nuclear magnetic resonance of¹⁷⁵Hf oriented at low temperature in iron has been observed with a sample prepared by ion implantation. The centre frequency of the broad resonance line isv _L (B _ext = 0)=138.53(36)MHz. Possible origins of the large inhomogeneous line width of FWHM=11.0(1.1) MHz are discussed. A comparison with model calculations for combined magnetic and electric hyperfine interaction indicates that the centre frequency may be interpreted as the magnetic interaction frequency for¹⁷⁵Hf in unperturbed substitutional sites of the host iron. With theg-factor of¹⁷⁵Hf from literature the magnetic hyperfine field of Hf in Fe is derived asB _hf=?64.9(9.3) T fitting well into systematics.     

The complexity of computing the tutte polynomial on transversal matroids

The complexity of computing the Tutte polynomialT(M,x,y) is determined for transversal matroidM and algebraic numbersx andy. It is shown that for fixedx andy the problem of computingT(M,x,y) forM a transversal matroid is #P-complete unless the numbersx andy satisfy (x−1)(y−1)=1, in which case it is polynomial-time computable. In particular, the problem of counting bases in a transversal matroid, and of counting various types of “matchable” sets of nodes in a bipartite graph, is #P-complete.     

Principles and applications of quality control by near infrared spectroscopy using the example of polymer additives

Due to its easy application, modern Near Infrared instrumentation is paid increasing attention when considering quality control in the chemical plant. The philosophy of spectrometric quality control and its possibilities and limitations are discussed on the basis of information theory considerations. Considering a group of 74 polymer additives it is shown how, by differentiated calibration with the aid of principal component analysis (PCA), a system could be designed for successfully controlling the quality of incoming products.     

Banking behaviour after the lifecycle event of “moving in together”: An exploratory study of the role of marketing investments

This study addresses an important issue for both managers and researchers: whether it is advantageous for financial services providers to invest in youth marketing. More specifically, the effectiveness of these investments is evaluated in terms of retention proneness once youngsters enter the lifecycle event of “moving in together”. The study identifies eight constructs of youth marketing and contrasts their impact against the best deal when youngsters decide to move in together and consequently experience the need to buy their first collectivized financial products, such as a joint account or a mortgage for their new home. Furthermore, the influence of the partner, prior patronage behaviour, customer demographics and psychographic variables are tested for. The findings of the study reveal that: (i) individuals are likely to change their banking behaviour during crucial lifetime events such as moving in together, (ii) not all youth marketing investments are equally effective, while (iii) the best deal components (e.g. convenience, price conditions, etc.) have a major impact.