5,722 research outputs found
Solid state NMR and X-ray diffraction studies of α-d-galacturonic acid monohydrate
Crystalline a-d-galacturonic acid monohydrate has been studied by 13C CPMAS NMR and X-ray crystallography. The molecular dynamics were investigated by evaluating 13C spin-lattice relaxation in the rotating frame (T1?) and chemical-shift-anisotropy properties of each carbon. Only limited molecular motions can be detected in the low frequency
The CO2 âbroadened H2O continuum in the 100â1500 cm -1 region: Measurements, predictions and empirical model
Transmission spectra of H2O + CO2 mixtures have been recorded, at 296, 325 and 366 K, for various pres- sures and mixture compositions using two experimental setups. Their analysis enables to retrieve values of the âcontinuumâabsorption by the CO2 -broadened H2O line wings between 100 and 1500 cm-1 . The results are in good agreement with those, around 1300 cm-1 , of the single previous experimental study available. Comparisons are also made with direct predictions based on line-shape correction factors Ï calculated, almost thirty years ago, using a quasistatic approach and an input H2O âCO2 intermolecular potential. They show that this model quite nicely predicts, with slightly overestimated values, the con- tinuum over a spectral range where it varies by more than three orders of magnitude. An empirical cor- rection is proposed, based on the experimental data, which should be useful for radiative transfer and climate studies in CO2 rich planetary atmospheres
Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)
The report of an IUPAC Task Group, formed in 2011 on "Intensities and line
shapes in high-resolution spectra of water isotopologues from experiment and
theory" (Project No. 2011-022-2-100), on line profiles of isolated
high-resolution rotational-vibrational transitions perturbed by neutral
gas-phase molecules is presented. The well-documented inadequacies of the Voigt
profile (VP), used almost universally by databases and radiative-transfer
codes, to represent pressure effects and Doppler broadening in isolated
vibrational-rotational and pure rotational transitions of the water molecule
have resulted in the development of a variety of alternative line-profile
models. These models capture more of the physics of the influence of pressure
on line shapes but, in general, at the price of greater complexity. The Task
Group recommends that the partially Correlated quadratic-Speed-Dependent
Hard-Collision profile should be adopted as the appropriate model for
high-resolution spectroscopy. For simplicity this should be called the
Hartmann--Tran profile (HTP). The HTP is sophisticated enough to capture the
various collisional contributions to the isolated line shape, can be computed
in a straightforward and rapid manner, and reduces to simpler profiles,
including the Voigt profile, under certain simplifying assumptions.Comment: Accepted for publication in Pure and Applied Chemistr
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The COââbroadened HâO continuum in the 100â1500cm-1 region: Measurements, predictions and empirical model
Transmission spectra of HâO+COâ mixtures have been recorded, at 296, 325 and 366âŻK, for various pressures and mixture compositions using two experimental setups. Their analysis enables to retrieve values of the âcontinuumâ absorption by the COâ-broadened H2âO line wings between 100 and 1500âŻcm-1. The results are in good agreement with those, around 1300âŻcm-1, of the single previous experimental study available. Comparisons are also made with direct predictions based on line-shape correction factors Ï calculated, almost thirty years ago, using a quasistatic approach and an input HâOâCOâ intermolecular potential. They show that this model quite nicely predicts, with slightly overestimated values, the continuum over a spectral range where it varies by more than three orders of magnitude. An empirical correction is proposed, based on the experimental data, which should be useful for radiative transfer and climate studies in CO2 rich planetary atmospheres
A Tool for Sheep Product Quality: Custom Microarrays from Public Databases
Milk and dairy products are an essential food and an economic resource in many countries. Milk component synthesis and secretion by the mammary gland involve expression of a large number of genes whose nutritional regulation remains poorly defined. The purpose of this study was to gain an understanding of the genomic influence on milk quality and synthesis by comparing two sheep breeds with different milking attitude (Sarda and Gentile di Puglia) using sheep-specific microarray technology. From sheep ESTs deposited at NCBI, we have generated the first annotated microarray developed for sheep with a coverage of most of the genome
Which quality of life score is best for glaucoma patients and why?
<p>Abstract</p> <p>Background</p> <p>The glaucomas are generally asymptomatic diseases until they are very advanced. They affect 2% of the population over 40 years of age and therefore represent a significant public health issue. There have been a number of attempts to develop quality of life scales for the disease. This review discusses the pros and cons of these scales and suggests the best of the current ones for use in a clinical setting.</p> <p>Methods</p> <p>Medline, Embase and Google Scholar were searched for relevant articles. No time period was defined and all types of article were included.</p> <p>Results</p> <p>11 Quality of Life scores were identified that have been used with glaucoma patients.</p> <p>Conclusion</p> <p>There is no generally accepted 'best' Quality of Life instrument for use in glaucoma. Many of the scales are biased towards physical symptoms and do little to address the personal or social factors of the disease. Further work is needed to produce scales that address all these areas as well as being simple to administer in a clinical setting.</p
Introducing the 2-DROPS model for two-dimensional simulation of crop roots and pesticide within the soil-root zone
Mathematical models of pesticide fate and behaviour in soils have been developed over the last 30 years. Most models simulate fate of pesticides in a 1-dimensional system successfully, supporting a range of applications where the prediction target is either bulk residues in soil or receiving compartments outside of the soil zone. Nevertheless, it has been argued that the 1-dimensional approach is limiting the application of knowledge on pesticide fate under specific pesticide placement strategies, such as seed, furrow and band applications to control pests and weeds. We report a new model (2-DROPS; 2-Dimensional ROots and Pesticide Simulation) parameterised for maize and we present simulations investigating the impact of pesticide properties (thiamethoxam, chlorpyrifos, clothianidin and tefluthrin), pesticide placement strategies (seed treatment, furrow, band and broadcast applications), and soil properties (two silty clay loam and two loam top soils with either silty clay loam, silt loam, sandy loam or unconsolidated bedrock in the lower horizons) on microscale pesticide distribution in the soil profile. 2-DROPS is to our knowledge the first model that simulates temporally- and spatially-explicit water and pesticide transport in the soil profile under the influence of explicit and stochastic development of root segments. This allows the model to describe microscale movement of pesticide in relation to root segments, and constitutes an important addition relative to existing models. The example runs demonstrate that the pesticide moves locally towards root segments due to water extraction for plant transpiration, that the water holding capacity of the top soil determines pesticide transport towards the soil surface in response to soil evaporation, and that the soil type influences the pesticide distribution zone in all directions. 2-DROPS offers more detailed information on microscale root and pesticide appearance compared to existing models and provides the possibility to investigate strategies targeting control of pests at the root/soil interface
Real Time Animation of Virtual Humans: A Trade-off Between Naturalness and Control
Virtual humans are employed in many interactive applications using 3D virtual environments, including (serious) games. The motion of such virtual humans should look realistic (or ânaturalâ) and allow interaction with the surroundings and other (virtual) humans. Current animation techniques differ in the trade-off they offer between motion naturalness and the control that can be exerted over the motion. We show mechanisms to parametrize, combine (on different body parts) and concatenate motions generated by different animation techniques. We discuss several aspects of motion naturalness and show how it can be evaluated. We conclude by showing the promise of combinations of different animation paradigms to enhance both naturalness and control
Magnetism in reduced dimensions
We propose a short overview of a few selected issues of magnetism in reduced
dimensions, which are the most relevant to set the background for more
specialized contributions to the present Special Issue. Magnetic anisotropy in
reduced dimensions is discussed, on a theoretical basis, then with experimental
reports and views from surface to single-atom anisotropy. Then conventional
magnetization states are reviewed, including macrospins, single domains,
multidomains, and domain walls in stripes. Dipolar coupling is examined for
lateral interactions in arrays, and for interlayer interactions in films and
dots. Finally thermally-assisted magnetization reversal and superparamagnetism
are presented. For each topic we sought a balance between well established
knowledge and recent developments.Comment: 13 pages. Part of a Special Issue of the C. R. Physique devoted to
spinelectronics (2005
A global perspective on marine photosynthetic picoeukaryote community structure
A central goal in ecology is to understand the factors affecting the temporal dynamics and spatial distribution of microorganisms and the underlying processes causing differences in community structure and composition. However, little is known in this respect for photosynthetic picoeukaryotes (PPEs), algae that are now recognised as major players in marine CO2 fixation. Here, we analysed dot blot hybridisation and cloningâsequencing data, using the plastid-encoded 16S rRNA gene, from seven research cruises that encompassed all four ocean biomes. We provide insights into global abundance, α- and ÎČ-diversity distribution and the environmental factors shaping PPE community structure and composition. At the class level, the most commonly encountered PPEs were Prymnesiophyceae and Chrysophyceae. These taxa displayed complementary distribution patterns, with peak abundances of Prymnesiophyceae and Chrysophyceae in waters of high (25:1) or low (12:1) nitrogen:phosphorus (N:P) ratio, respectively. Significant differences in phylogenetic composition of PPEs were demonstrated for higher taxonomic levels between ocean basins, using Unifrac analyses of clone library sequence data. Differences in composition were generally greater between basins (interbasins) than within a basin (intrabasin). These differences were primarily linked to taxonomic variation in the composition of Prymnesiophyceae and Prasinophyceae whereas Chrysophyceae were phylogenetically similar in all libraries. These data provide better knowledge of PPE community structure across the world ocean and are crucial in assessing their evolution and contribution to CO2 fixation, especially in the context of global climate change
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