Surface Parameters (surface + parameter)

Distribution by Scientific Domains


Selected Abstracts


Synthesis of new cationic surfactants based on recycled poly(ethylene terephthalate) for deinking of solvent-based ink from low-density polyethylene surface

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010
Samya I. El-Sherbiny
Abstract Water-soluble oligomers based on poly-(ethylene terephthalate) waste, PET, were prepared from transesterification of PET with diethanolamine and triethanolamine in the presence of manganese acetate as a catalyst at temperature of 200°C for 8 h. New cationic surfactants were prepared by reaction of the produced recycled oligomers with bromoacetic acid followed by quaternization with pyridine. The chemical structure of the prepared surfactants was confirmed by 1H-NMR analysis. The surface tension, critical micelle concentration, and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration (,max max), the area per molecule at interface (Amin), and the effectiveness of surface tension reduction (,CMC) were determined from the adsorption isotherms of the prepared surfactants. The prepared surfactants were tested as ink removal for printed low-density polyethylene surface. The effect of surfactants concentrations, pH, soaking time, and shaking time were investigated for deinking process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]


The Role of OTS Density on Pentacene and C60 Nucleation, Thin Film Growth, and Transistor Performance

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009
Ajay Virkar
Abstract In organic thin film transistors (OTFTs), charge transport occurs in the first few monolayers of the semiconductor near the semiconductor/dielectric interface. Previous work has investigated the roles of dielectric surface energy, roughness, and chemical functionality on performance. However, large discrepancies in performance, even with apparently identical surface treatments, indicate that additional surface parameters must be identified and controlled in order to optimize OTFTs. Here, a crystalline, dense octadecylsilane (OTS) surface modification layer is found that promotes two-dimensional semiconductor growth. Higher mobility is consistently achieved for films deposited on crystalline OTS compared to on disordered OTS, with mobilities as high as 5.3 and 2.3,cm2,V,1,s,1 for C60 and pentacene, respectively. This is a significant step toward morphological control of organic semiconductors which is directly linked to their thin film charge carrier transport. [source]


Performance assessment of a GCM land surface scheme using a fine-scale calibrated hydrological model: an evaluation of MOSES for the Nile Basin

HYDROLOGICAL PROCESSES, Issue 11 2009
Mohamed Ezzat Elshamy
Abstract Land surface schemes (LSSs) represent the interface between land surface and the atmosphere in general circulation models (GCMs). Errors in LSS-simulated heat and moisture fluxes can result from inadequate representation of hydrological features and the derivation of effective surface parameters for large heterogeneous GCM gridboxes from small-scale observations. Previous assessments of LSS performance have generally compared simulated heat and moisture fluxes to observations over a defined experimental domain for a limited period. A different approach has been evaluated in this study, which uses a fine-resolution calibrated hydrological model of the study basin to provide a quasi-observed runoff series for direct comparison with simulated runoff from a selected LSS at GCM scale. The approach is tested on two GCM gridboxes covering two contrasting regions within the Nile Basin. Performance is mixed; output from the LSS is generally compatible with that of the fine-resolution model for one gridbox while it cannot reproduce the runoff dynamics for the other. The results also demonstrate the high sensitivity of runoff and evapotranspiration to radiation and precipitation inputs and show the importance of subtle issues such as temporal disaggregation of climatic inputs. We conclude that the use of a fine-resolution calibrated model to evaluate a LSS has several advantages, can be generalized to other areas to improve the performance of global models and provides useful data that can be used to constrain LSS parameterizations. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Methods for retrieving hydrologically significant surface parameters from remote sensing: a review for applications to east Asia region

HYDROLOGICAL PROCESSES, Issue 4 2009
Bunkei Matsushita
Abstract As human populations and resource use continue to increase, water quality and water resource management will become major problems. With its advantages of large area coverage, high spatial resolution, frequent update and consistent quality, remote sensing has been widely used for hydrological studies and water resources management. This paper focuses on three potential functions of remote sensing for hydrological analysis in east Asia: (1) monitoring water quality in turbid lakes; (2) extracting impervious surface areas (ISAs) from watersheds and (3) estimating evapotranspiration in semi-arid areas. Reviewing the results of the above three topics, it becomes clear that the ability of the current remote sensing technique is still limited in terms of its use in hydrological simulations. An alternative to improving the sensors is developing effective algorithms to compensate for the limitations of current satellite sensors. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Impact of spatial variations of land surface parameters on regional evaporation: a case study with remote sensing data

HYDROLOGICAL PROCESSES, Issue 9 2001
Hussein O. Farah
Abstract Most precipitation in watersheds is consumed by evaporation, thus techniques to appraise regional evaporation are important to assess the availability of water resources. Many algorithms to estimate evaporation from remotely sensed spectral data have been developed in the recent past. In addition to differences in the physical parameterization of surface fluxes, these algorithms have different solutions for describing spatial variations of the parameters in the soil,vegetation,atmosphere,transfer (SVAT) continuum. In this study, the necessity to spatially distinguish SVAT parameters for computing surface heat fluxes is analysed for the Naivasha watershed in the Kenyan Rift Valley. Landsat Thematic Mapper (TM) spectral data have been used to first delineate the watershed into 15 hydrological units using surface temperature, normalized difference vegetation index and surface albedo as attributes. Thereafter, semi-empirical relationships between these TM-based parameters and other SVAT parameters have been applied to compute the spatial variation of SVAT parameters and the associated evaporation from the different hydrological units. The impact of using watershed-constant or watershed-distributed SVAT parameters on the fluxes is analysed. The determination of watershed averaged evaporation with area-aggregated SVAT parameters is feasible without significant loss of accuracy. Distributed evaporation in heterogeneous watersheds, however, can be investigated only with remote sensing flux algorithms that can account for spatially variable air temperature, surface roughness, surface albedo and the stability correction of the temperature profile due to buoyancy. Erroneous results can be expected if area-aggregated SVAT parameters are used to calculate local evaporation. As most of the recently developed remote sensing flux algorithms are based on areal constant SVAT parameters, direct applications in watersheds are still limited. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Determination of age-related changes in the morphological structure (sagging) of the human cheek using a photonumeric scale and three-dimensional surface parameters

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2000
Tsukahara
Synopsis The usefulness of the photo standard for evaluating skin sagging in the face, especially in the cheeks, was evaluated. A six-stage photo standard was prepared using photos of women aged 17,83-years-old at three magnification rates (136,188 women in each group). Based on this photo standard, scoring was performed using a six-grade scoring system by two specialists to obtain the consensus score. Scoring was also performed in parallel by five general observers. The degree of agreement between the two scores was evaluated by calculating the Kappa value. In each group, the Kappa value was 0.452,0.563, indicating moderate agreement. Thus, the photo standard may be useful for evaluating sagging. Based on the photo standard, a score of 2, at which sagging becomes detectable appeared at the age of 40 years. In parallel, 3D analysis of replicas around the cheek was performed to morphologically analyse age-related changes in sagging. When the depth parameter was compared between the nasolabial groove and the mouth corners, a higher value was observed in the nasolabial groove until the age of 40 years, but higher values were seen in the mouth corners thereafter. This may have been because sagging in the cheeks descends to the area around the mouth, resulting in reversion in the sWv value. These findings indicated that sagging in the cheeks becomes morphologically distinct in women in their forties. Résumé L'utilité du critère photographique afin d'évaluer l'affaissement cutané du visage, et notamment des joues, a étéévaluée. Un critère photographique en six phases a été préparé au moyen de photographies de femmes âgées de 17 à 83 ans avec trois niveaux d'agrandissement différents (136,188 femmes dans chaque groupe). En se basant sur ce critère, on a procédéà une évaluation au moyen d'un système ou échelle d'évaluation comprenant six degrés par des deux spécialistes afin d'obtenir une évaluation de référence consensuelle. Parallèlement, cinq observateurs ordinaires ont également procédéà une évaluation. Le degré d'accord entre ces deux évaluations a été estimé en calculant la valeur Kappa. Dans chaque groupe, la valeur Kappa se situait entre 0,452 et 0,563, indiquant un consensus modéré. Par conséquent, le critère photographique peut être utile afin d'évaluer l'affaissement cutané. En se basant sur le critère photographique, une évaluation de degré 2, à partir duquel l'affaissement devient détectable, est apparu à l'âge de 40 ans. Parallèlement, une analyse tridimensionnelle de répliques autour des joues a été réalisée afin d'analyser morphologiquement les modifications selon l'âge de l'affaissement. Lorsque le paramètre de profondeur a été comparé entre le sillon nasolabial et les commissures des lèvres, une valeur supérieure a été observée pour le sillon nasolabial jusqu'à l'âge de 40 ans, mais des valeurs plus élevées ont été enregistrées pour les commissures des lèvres après 40 ans. Ceci peut être dû au fait que l'affaissement des joues descend vers la zone située autour de la bouche, conduisant à une réversion de la valeur sWv. Ces résultats indiquent que l'affaissement des joues devient morphologiquement apparent chez les femmes dés la quarantaine. [source]


Discrete output feedback sliding-mode control with integral action

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2006
Nai One Lai
Abstract This paper presents a novel approach to the problem of discrete time output feedback sliding-mode control design. The method described applies to uncertain systems (with matched uncertainties) which are not necessarily minimum phase or relative degree one. A new sliding surface is proposed, which is associated with the equivalent control of the output feedback sliding-mode controller. Design freedom is available to select the sliding surface parameters to produce an appropriate reduced-order sliding motion. In order for this to be achieved, a static output feedback condition associated with a certain reduced-order system obtained from the original plant must be solvable. The practicality of the results are demonstrated through the implementation of the controller on a small DC motor test rig. Copyright © 2005 John Wiley & Sons, Ltd. [source]


The use of topography-based parameters for the assessment and prediction of surface wear

LUBRICATION SCIENCE, Issue 1 2000
I. Sherrington
Abstract This paper examines the use of surface parameters as ,tools' for assessing and predicting surface wear. It begins by briefly reviewing other work published on wear assessment based on entirely topography-based parameters, and concludes that other elements of surface condition are needed, in addition to topography, to assess and characterise the contact if topography-based parameters are to be employed to predict wear. This paper discusses why areal measurements of bearing area and plasticity index are suitable candidates as a basis for assessing and predicting surface wear, and outlines the potential value of using these parameters in conjunction with a wear equation. The validity of this suggestion is illustrated by some preliminary data from a series of pin-on-disc wear experiments involving areal assessments of the bearing area and plasticity index of the rough tip of a brass pin. Predictions of the first stage of a wear simulation are compared to experimental data, and the paper concludes by presenting some general conclusions and suggestions about how the work could be developed. [source]


Simulation of the mean urban heat island using 2D surface parameters: empirical modelling, verification and extension

METEOROLOGICAL APPLICATIONS, Issue 3 2009
Bernadett Balázs
Abstract The spatial distribution of the annual mean urban heat island (UHI) intensity was simulated applying empirical models based on datasets from urban areas of Szeged and Debrecen, using simple and easily determinable urban surface cover variables. These two cities are situated on the Alföld (Great Hungarian Plain) and have similar topographic and climatic conditions. Temperature field measurements were carried out, Landsat satellite images were evaluated, and then one- and multiple variable models were constructed using linear regression techniques. The selected multiple-parameter models were verified using independent datasets from three urban settlements. In order to obtain some impression of the mean UHI patterns in other cities with no temperature measurements available, the better model was extended to urban areas of four other cities situated in geographical environments similar to Szeged and Debrecen. The main shortcoming of typical empirical models, namely that they are often restricted to a specific location, is overcome by the obtained model since it is not entirely site but more region specific, and valid in a large and densely populated area with several settlements. Copyright © 2009 Royal Meteorological Society [source]


The immediate-early oncoproteins Fra-1, c-Fos, and c-Jun have distinguishable surface behavior and interactions with phospholipids

BIOPOLYMERS, Issue 9 2009
María Cecilia Gaggiotti
Abstract This work explores the surface properties of the transcription factor Fra-1 and compares them with those of two other immediate early proteins, c-Fos and c-Jun, to establish generalities and differences in the surface behavior and interaction with phospholipids of this type of proteins. We present several experimental clues of the flexible nature of Fra-1, c-Fos, and c-Jun that support sequence-based predictions of their intrinsical disorder. The values of surface parameters for Fra-1 are similar in general to those of c-Fos and c-Jun. However, we find differences in the interactions of the three proteins with phospholipids. The closely related Fra-1 and c-Fos share affinity for anionic lipids but the former has more affinity for a condensed phase and senses a change in DPPC phase, while the latter has more affinity for an expanded phase. These features are in contrast with our previous finding that c-Jun is not selective for phospholipid polar head group or charge. We show here that at least some immediate early transcription factors can interact with membrane phospholipids in a distinguishable manner, and this shall provide a basis for their potential capacity to regulate membrane-mediated cellular processes. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 710,718, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]


Menstrual cycle influences ocular surface parameters in normal and dry eye patients

ACTA OPHTHALMOLOGICA, Issue 2007
P VERSURA
Purpose: We analyzed the changes of ocular surface parameters and symptoms in healthy and dry eye women over the menstrual cycle. To our knowledge, incomplete reports appear in the literature on this issue in healthy women still in the fertile period, and none on dry eye women of the same age. This to comparatively evaluate what then happens in peri- and post-menopause. Methods: 29 females in the fertile age and a regular 26-29 days menstrual cycle were included in the study. 14 subjects with and 15 without dry eye symptoms. Symptoms were scored by the validate questionnaire OSDI. Degree of dryness was evaluated with the Schirmer test I, Jones test, BUT, Ferning test, Tear Function Index (TFI) and conjunctival imprint cytology. Degree of inflammation was evaluated with conjunctival brush cytology and dosage of exudated serum albumin in tears. Hormonal cytology procedures were applied to exfoliated cells in tears. Patients were analysed during menstruation, in the follicular and in luteal phases over two consecutive cycles and results were statistically evaluated Results: TFI, tear stability, surface dryness and inflammation were significantly related to the hormonal fluctuations in menstrual cycle, in particular to the estrogen peak occurring during the follicular phase, especially in dry eye patients. Subjective symptoms appeared to increase in the luteal phase, suggesting the presence of a pre-menstrual syndrome Conclusions: The ocular surface is confirmed to be dependent from hormonal variations; clinicians would take into account these cyclic variations during the examinations of subjects still in the fertile age, with dryness symptoms [source]