1,007 research outputs found
Microreactor cells for high throughput x-ray absorption spectroscopy
High-throughput experimentation has been applied to X-ray Absorption spectroscopy as a novel route for increasing research productivity in the catalysis community. Suitable instrumentation has been developed for the rapid determination of the local structure in the metal component of precursors for supported catalysts. An automated analytical workflow was implemented that is much faster than traditional individual spectrum analysis. It allows the generation of structural data in quasi-real time. We describe initial results obtained from the automated high throughput (HT) data reduction and analysis of a sample library implemented through the 96 well-plate industrial standard. The results show that a fully automated HT-XAS technology based on existing industry standards is feasible and useful for the rapid elucidation of geometric and electronic structure of materials
Application of Bifidobacteria as Starter Culture in Whole Wheat Sourdough Breadmaking
11 pages, 4 tables, 2 figures.-- Published online: 3 March 2011.-- The original publication is available at www.springerlink.comThis investigation is aimed at developing a new cereal-based product, with increased nutritional quality, by using Bifidobacterium pseudocatenulatum ATCC 27919 as starter in whole wheat sourdough fermentation and evaluating its performance. Four different sourdough levels (5%, 10%, 15%, and 20% on flour basis) in bread dough formulation were analysed. The effects of the use of bifidobacteria in sourdough bread were comparatively evaluated with controls (yeast and/or chemically acidified sourdough with antibiotics). The sourdough and dough fermentative parameters analysed were pH, total titratable acidity, d/l-lactic and acetic acids. Bread performance was evaluated by specific volume, slice shape, crumb structure and firmness, crust and crumb colour, pH, total titratable acidity, and d/l-lactic and acetic acids, phytate, and lower myo-inositol phosphate contents. The sourdough breads showed similar technological quality to the control sample, with the exception of specific bread volume (decreased from 2.46 to 2.22 mL/g) and crumb firmness (increased from 2.61 to 3.18 N). Sourdough inoculated with bifidobacteria significantly increased the levels of organic acids in fermented dough and bread. The Bifidobacterium strain contributed to the fermentation process, increasing phytate hydrolysis during fermentation owing to the activation of endogenous cereal phytase and its own phytase, resulting in bread with significantly lower phytate levels (from 7.62 to 1.45 Ī¼mol/g of bread in dry matter). The inclusion of sourdough inoculated with bifidobacteria made possible the formulation of whole wheat bread with positive changes in starch thermal properties and a delay and decrease in amylopectin retrogradation.This work was financially supported by grants AGL2006-09613/ALI, CSIC-200870I229, and Consolider Fun-C-Food CSD2007-00063 from the Ministry of Science and Innovation, Spain (MICINN). The scholarship of J.M. Sanz Penella and the contract of J.A. Tamayo Ramos from MICINN are greatly acknowledged.Peer reviewe
Mathematical Reflections on Acupoint Combinations in the Traditional Meridian Systems
The meridian system is a systematic order of empirical knowledge functioning as a rational ground for a balanced treatment by combining meridians. In TCM theory, a continuous circulation of Qi through 12 meridians is postulated, described as the Chinese clock (CC). On this basis, combinations of meridians and acupoints had been described in historical writings. The most common is the interior/exterior system beside the neighbouring system, the opposite clock system, and three systems, developed out of the theory of the six stages. All of these represent symmetrical combinations, which were defined by the steps in the CC. We calculated the possible combinations that fit into the systematics of the historical descriptions, leading to 19 systems. Merging the data of the 19 systems, possible steps in the CC clock for balancing a meridian are 1, 2, 3, and 6. Step 4 is not possible. Step 5 is a combinatory possibility but has no widespread tradition except for activating the yin extraordinary vessels. These possibilities can be plotted on the CC as a powerful tool for daily practice. Only two meridians might be excluded as potentially balancing meridians, so it seems almost impossible to define noneffective acupuncture points as controls in clinical trials
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Laser and electron deflection from transverse asymmetries in laser-plasma accelerators.
We report on the deflection of laser pulses and accelerated electrons in a laser-plasma accelerator (LPA) by the effects of laser pulse front tilt and transverse density gradients. Asymmetry in the plasma index of refraction leads to laser steering, which can be due to a density gradient or spatiotemporal coupling of the laser pulse. The transverse forces from the skewed plasma wave can also lead to electron deflection relative to the laser. Quantitative models are proposed for both the laser and electron steering, which are confirmed by particle-in-cell simulations. Experiments with the BELLA Petawatt Laser are presented which show controllable 0.1-1 mrad laser and electron beam deflection from laser pulse front tilt. This has potential applications for electron beam pointing control, which is of paramount importance for LPA applications
High throughput <i>in situ</i> EXAFS instrumentation for the automatic characterization of materials and catalysts
An XAS data acquisition and control system for the in situ analysis of dynamic materials libraries under control of temperature and gaseous environment has been developed. It was integrated at the SRS in Daresbury, UK, beamline 9.3, using a Si (220) monochromator and a 13 element solid state Ge fluorescence detector. The core of the system is an intelligent X, Y, Z, Īø positioning system coupled to multi-stream quadrupole mass spectrometry analysis (QMS). The system is modular and can be adapted to other synchrotron radiation beamlines. The entire software control was implemented using Labview and allows the scan of a variety of library sizes, in several positions, angles, gas compositions and temperatures with minimal operator intervention. The system was used for the automated characterization of a library of 91 catalyst precursors containing ternary combinations of Cu, Pt, and Au on Ī³-Al2O3, and for the evaluation and structural characterization of eight Au catalysts supported on A12O3 and TiO2. Mass spectrometer traces reveal conversion rate oscillations in 6wt % Au/Ī³Al2O3 catalysts. The use of HT experimentation for in situ EXAFS studies demonstrates the feasibility and potential of HT in situ XAFS for synchrotron radiation studies
High-throughput synthesis and characterization of BiMoVOX materials
The high throughput synthesis and characterization of a particular family of ceramic materials, bismuth
molybdenum vanadium oxides (BiMoVOX), suitable as inorganic yellow pigments and low temperature oxidation
catalysts, is described. Samples, synthesized by calcination and peroxo sol-gel methods, are characterized by X-ray
powder diffraction, UV-visible and XAFS spectroscopy. A combined high-throughput XRD/XAFS study of a 54
samples array, with simultaneous refinement of data of both techniques, has been performed. Molybdenum doping of
bismuth vanadate results in a phase transition from monoclinic BiV04 to tetragonal Bi(V,Mo)04, both of scheelite type.
Both central metals, V5+ and Mo6+, remain in a tetrahedral coordination. UV/visible spectroscopy identifies a linear blue
shift as a function of Mo6+ amount
pH and Solvent Influence on p-Aminobenzoic Acid
Through X-ray absorption and emission spectroscopies, the chemical, electronic
and structural properties of organic species in solution can be observed.
Near-edge X-ray absorption fine structure (NEXAFS) and resonant inelastic
X-ray scattering (RIXS) measurements at the nitrogen K-edge of para-
aminobenzoic acid reveal both pH- and solvent-dependent variations in the
ionisation potential (IP), 1sāĻ* resonances and HOMOāLUMO gap. These changes
unequivocally identify the chemical species (neutral, cationic or anionic)
present in solution. It is shown how this incisive chemical state sensitivity
is further enhanced by the possibility of quantitative bond length
determination, based on the analysis of chemical shifts in IPs and Ļ*āshape
resonances in the NEXAFS spectra. This provides experimental access to
detecting even minor variations in the molecular structure of solutes in
solution, thereby providing an avenue to examining computational predictions
of solute properties and soluteāsolvent interactions
Pyroelectricity of silicon-doped hafnium oxide thin films
Ferroelectricity in hafnium oxide thin films is known to be induced by various doping elements and in solid-solution with zirconia. While a wealth of studies is focused on their basic ferroelectric properties and memory applications, thorough studies of the related pyroelectric properties and their application potential are only rarely found. This work investigates the impact of Si doping on the phase composition and ferro- as well as pyroelectric properties of thin film capacitors. Dynamic hysteresis measurements and the field-free Sharp-Garn method were used to correlate the reported orthorhombic phase fractions with the remanent polarization and pyroelectric coefficient. Maximum values of 8.21āĀµC cmā2 and ā46.2āĀµC Kā1 mā2 for remanent polarization and pyroelectric coefficient were found for a Si content of 2.0āat%, respectively. Moreover, temperature-dependent measurements reveal nearly constant values for the pyroelectric coefficient and remanent polarization over the temperature range of 0āĀ°C to 170āĀ°C, which make the material a promising candidate for IR sensor and energy conversion applications beyond the commonly discussed use in memory applications
A Combined Approach of Process Mining and Rule-based AI for Study Planning and Monitoring in Higher Education
This paper presents an approach of using methods of process mining and
rule-based artificial intelligence to analyze and understand study paths of
students based on campus management system data and study program models.
Process mining techniques are used to characterize successful study paths, as
well as to detect and visualize deviations from expected plans. These insights
are combined with recommendations and requirements of the corresponding study
programs extracted from examination regulations. Here, event calculus and
answer set programming are used to provide models of the study programs which
support planning and conformance checking while providing feedback on possible
study plan violations. In its combination, process mining and rule-based
artificial intelligence are used to support study planning and monitoring by
deriving rules and recommendations for guiding students to more suitable study
paths with higher success rates. Two applications will be implemented, one for
students and one for study program designers.Comment: 12 pages, 4 figures, conference, 30 reference
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