Flows on the nozzle plate of an inkjet printhead

Flow patterns of ink layers on the nozzle plate of a piezo-driven printhead are investigated. Two different flow types are identified. First, a jet of droplets induces a radial airflow in the direction of the jet, which in turn causes a liquid flow towards the nozzle. Second, the movement of the meniscus in the nozzle causes an equally strong flow, but completely different flow patterns. The results are presented in a phase diagram with pulse amplitude and firing frequency as parameters.     

Exploiting and controlling gel-to-crystal transitions in multicomponent supramolecular gels

Multicomponent supramolecular gels provide opportunities to form materials that are not accessible when using the single components alone. Different scenarios are possible when mixing multiple components, from complete co-assembly (mixing of the components within the self-assembled structures formed) to complete self-sorting such that each structure contains only one of the components. Most examples of multicomponent gels that currently exist form stable gels. Here, we show that this can be used to control the mechanical properties of the gels, but what is probably most exciting is that we show that we can use a magnetic field to control the shape of the crystals. The gelling component aligns in a magnetic field and so results in anisotropic crystals being formed.

Multicomponent supramolecular gels provide opportunities to form materials that are not accessible when using the single components alone.     

Relation Between Purity of an Open Qubit Dynamics and Its Initial Correlation with an Environment

Purity as a quantifier of an impact of environment on an open quantum system is studied for a qubit dephasingly interacting with its environment. We analyze how time evolution of the purity depends on initial states of the composite system both in the case of infinite and finite environments. It is shown that for a certain class of initial preparations, the purity of an evolving qubit state initially correlated with infinite environment can be greater than in the case of uncorrelated qubit-environment initial preparations. We identify a class of initial states leading to such desired outcome.     

Synchrotron Radiation and Polymer Science IV

The fourth meeting on the use of Synchrotron Radiation in Polymer Science (SRPS) was held in Rolduc Abbey, the Netherlands, from September 8 to 11, 2009. This was a continuation of a topical series that was started by H.G. Zachmann, one of the pioneers of the use of synchrotron radiation techniques in polymer science. Earlier meetings were held in Hamburg (1995), Sheffield (2002), and Kyoto (2006). The meeting was organized as a satellite to SAS 2009, which took place the following week in Oxford. The meeting was co-organized by the polymer groups of Leuven University (Belgium) and Eindhoven University of Technology (Netherlands), as well as the DUBBLE beam line (ESRF/NWO/FWO).     

Automatic vibration mode tracking using a scanning laser Doppler vibrometer

Optical measurement techniques are being used more and more for quality control in the production process. An important problem when trying to implement optical measurement systems, and in particular the scanning laser Doppler vibrometer (SLDV) which is considered in this paper, is that user interaction is always required. The need for user interaction implies an increase in testing time and cost and also brings an additional source of variability of the test results. In this article, a completely autonomous test procedure is developed to track the vibration behavior of a product during the production process (this includes automatic laser focussing, position calibration, object recognition, grid generation and mode estimation). The proposed procedure typically requires a few minutes only to automatically determine a high-resolution model of the vibration behavior. The method will be validated on measurements of an electronic circuit board.     

Ultrasoft magnetic films investigated with Lorentz tranmission electron microscopy and electron holography.

As a tribute to the scientific work of Professor Gareth Thomas in the field of structure-property relationships this paper delineates a new possibility of Lorentz transmission electron microscopy (LTEM) to study the magnetic properties of soft magnetic films. We show that in contrast to the traditional point of view, not only does the direction of the magnetization vector in nano-crystalline films make a correlated small-angle wiggling, but also the magnitude of the magnetization modulus fluctuates. This fluctuation produces a rapid modulation in the LTEM image. A novel analysis of the ripple structure in nano-crystalline Fe-Zr-N film corresponds to an amplitude of the transversal component of the magnetization deltaMy of 23 mT and a longitudinal fluctuation of the magnetization of the order of deltaMx = 30 mT. The nano-crystalline (Fe99Zr1)1-xNx films have been prepared by DC magnetron reactive sputtering with a thickness between 50 and 1000 nm. The grain size decreased monotonically with N content from typically 100 nm in the case of N-free films to less than 10 nm for films containing 8 at%. The specimens were examined with a JEOL 2010F 200 kV transmission electron microscope equipped with a post column energy filter (GIF 2000 Gatan Imaging Filter). For holography, the microscope is mounted with a biprism (JEOL biprism with a 0.6 microm diameter platinum wire).     

Tetrabutylammonium triphenyldifluorosilicate (TBAT) initiated intramolecular addition of allylsilanes to 2,3-dihydro-4-pyridones. A novel route for the stereoselective construction of indolizidine systems

A general and preparatively simple access to multisubstituted indolizidines has been developed. The key step involves the fluoride ion induced intramolecular reaction of 2,3-dihydro-4-pyridones with allylsilane located in the side-chain.     

Synthesis of a Phosphorylated Disaccharide Fragment of the O‐Specific Polysaccharide of Vibrio cholerae O139, Functionalized for Conjugation

The title disaccharide, 2‐{2‐{2‐[(2‐ethoxy‐3,4‐dioxocyclobut‐1‐en‐1‐yl)amino]ethoxy}ethoxy}ethyl 2‐O‐(3,6‐dideoxy‐α‐L ‐xylo‐hexopyranosyl)‐β‐d‐ galactopyranoside cyclic 4,6‐(potassium phosphate) ( 2 ), was synthesized from the two isomeric linker‐equipped galactose acceptors 9 and 10 , obtained by phosphorylation of 2‐[2‐(2‐azidoethoxy)ethoxy]ethyl 3‐O‐benzyl‐β‐d‐ galactopyranoside ( 8 ), which were glycosylated with ethyl 2,4‐di‐O‐benzyl‐3,6‐dideoxy‐1‐thio‐β‐l‐ xylo‐hexopyranoside ( 12 ; Scheme). Mainly the fully protected α‐(1 → 2)‐linked products 13 α and 14 α were formed. Catalytic hydrogenolysis/hydrogenation effected global deprotection, thereby removing the chirality at the P‐atom, and simultaneously converted the azido group in the linker to an amino group (→ 15 ). Final treatment with diethyl squarate (= 3,4‐diethoxycyclobut‐3‐ene‐1,2‐dione) gave target compound 2 , amenable for conjugation to proteins.     

Impact of the sample matrix composition on the signal enhancement in the capillary electrophoretic separation of poliovirus samples

The development of capillary electrophoretic applications aiming to provide reliable stability assessment of viral suspensions, to detect subviral particles from cell extracts or to study the interactions between virus particles and various biomolecules, cannot be done without a thorough understanding of the sample matrix contribution to the observed electrophoretic behaviour. The present study thoroughly investigates the effect of the sample matrix on the electrophoretic behaviour of poliovirus injected as sample plugs of 1%, 5% and 12% effective capillary length. The effect of the sample matrix for three different poliovirus batches was evaluated. Additionally, simulated samples, obtained from concentrated poliovirus suspensions of high purity and diluted with commonly used lab buffers in order to obtain samples with either high or low conductivities, were also investigated. The goal of the study was to obtain a better understanding of the effect of the sample matrix on the signal enhancement, in order to define a general approach allowing a repeatable capillary electrophoretic (CE) separation of poliovirus from complex samples. This study clearly demonstrates that the sample matrix has an important influence on the sensitivity of the CE poliovirus separations. Translation of these observations into routine practice involves several compromises and a set of rules in order to reduce day-to-day variation and to maximize sensitivity.     

Polarized non-abelian representations of slim near-polar spaces

In (Bull Belg Math Soc Simon Stevin 4:299–316, 1997), Shult introduced a class of parapolar spaces, the so-called near-polar spaces. We introduce here the notion of a polarized non-abelian representation of a slim near-polar space, that is, a near-polar space in which every line is incident with precisely three points. For such a polarized non-abelian representation, we study the structure of the corresponding representation group, enabling us to generalize several of the results obtained in Sahoo and Sastry (J Algebraic Comb 29:195–213, 2009) for non-abelian representations of slim dense near hexagons. We show that with every polarized non-abelian representation of a slim near-polar space, there is an associated polarized projective embedding.