1,173 research outputs found
Structural Geology of the Cariboo Gold Mining District, East-Central British Columbia:
No full textL.C. Struik.Memoir (Geological Survey of Canada) ; 421
Depolarization and decreased surface expression of K+ channels contribute to NSAID-inhibition of intestinal restitution
No full textNon-steroidal anti-inflammatory drugs (NSAIDs) contribute to gastrointestinal ulcer formation by inhibiting epithelial cell migration and mucosal restitution; however, the drug-affected signaling pathways are poorly defined. We investigated whether NSAID inhibition of intestinal epithelial migration is associated with depletion of intracellular polyamines, depolarization of membrane potential (Em) and altered surface expression of K+ channels. Epithelial cell migration in response to the wounding of confluent IEC-6 and IEC-Cdx2 monolayers was reduced by indomethacin (100μM), phenylbutazone (100μM) and NS-398 (100μM) but not by SC-560 (1μM). NSAID-inhibition of intestinal cell migration was not associated with depletion of intracellular polyamines. Treatment of IEC-6 and IEC-Cdx2 cells with indomethacin, phenylbutazone and NS-398 induced significant depolarization of Em, whereas treatment with SC-560 had no effect on Em. The Em of IEC-Cdx2 cells was: −38.5±1.8mV under control conditions; −35.9±1.6mV after treatment with SC-560; −18.8±1.2mV after treatment with indomethacin; and −23.7±1.4mV after treatment with NS-398. Whereas SC-560 had no significant effects on the total cellular expression of Kv1.4 channel protein, indomethacin and NS-398 decreased not only the total cellular expression of Kv1.4, but also the cell surface expression of both Kv1.4 and Kv1.6 channel subunits in IEC-Cdx2. Both Kv1.4 and Kv1.6 channel proteins were immunoprecipitated by Kv1.4 antibody from IEC-Cdx2 lysates, indicating that these subunits co-assemble to form heteromeric Kv channels. These results suggest that NSAID inhibition of epithelial cell migration is independent of polyamine-depletion, and is associated with depolarization of Em and decreased surface expression of heteromeric Kv1 channels.ID: S0006295207001931; M3: Article; Accession Number: S0006295207001931; Author: L.C. Freeman (b); Author: D.F. Narvaez (a); Author: A. McCoy (a); Author: F.B. von Stein (c); Author: S. Young (b); Author: K. Silver (a); Author: S. Ganta (b); Author: D. Koch (b); Author: R. Hunter (b); Author: R.F. Gilmour (c); Author: J.D. Lillich (a, ⁎); Affiliation: Department of Clinical Sciences, Kansas State University, Manhattan, KS 66506, United States; Affiliation: Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, United States; Affiliation: Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, United States; Keyword: Non-steroidal anti-inflammatory drugs; Keyword: Intestinal epithelial cells; Keyword: Membrane potential; Keyword: Potassium channels; Number of Pages: 12; Language: English;Source type: Electronic(1)http://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=S0006295207001931&site=eds-live&scope=sit
Les Observations sur l'éloquence de l'abbé de Saint-Pierre
No full textAbbé de Saint-Pierre : Observations sur l'éloquence. Presented by Lawrence Kerslake.
Many of the abbé de Saint-Pierre's writings remain little-known or even unpublished. The Observations sur l'éloquence constitute his chief discussion of literature. A preliminary draft appeared in the Mercure in 1726, but the work subsequently underwent two major revisions, both states represented in Ms. R.248 of the Bibliothèque publique et universitaire in Neuchâtel. A further copy (BNF. N.a.fr. 11232), with a few additional changes, is published here. The ideas in the text show the author to be a 'Modern' in his position on beauty and literary effect, and reflect his life-long concern for the improvement of his fellow-citizens.Kerslake L.C. Les Observations sur l'éloquence de l'abbé de Saint-Pierre. In: Dix-huitième Siècle, n°31, 1999. Mouvement des sciences et esthétique(s) sous la direction de Christine Rolland, François Azouvi et Michel Baridon. pp. 305-328
A 0.53pJK<sup>2</sup> 7000μm<sup>2</sup> resistor-based temperature sensor with an inaccuracy of ±0.35°C (3σ) in 65nm CMOS
No full textIn microprocessors and DRAMs, on-chip temperature sensors are essential components, ensuring reliability by monitoring thermal gradients and hot spots. Such sensors must be as small as possible, since multiple sensors are required for dense thermal monitoring. However, conventional BJT-based temperature sensors are not compatible with the sub-1V supply of advanced processes. Subthreshold MOSFETs can operate from lower supplies, but at high temperatures their performance is limited by leakage [1,2]. Thermal diffusivity (TD) sensors achieve sub-1V operation and small area with moderate accuracy, but require milliwatts of power [3]. Recently, resistor-based sensors based on RC WienBridge (WB) filters have realized high resolution and energy efficiency [4,5]. Fundamentally, they are robust to process and supply-voltage scaling. However, their readout circuitry has been based on continuous-time (CT) ΔΣ ADCs or frequency-locked loops (FLLs), which require precision analog circuits and occupy considerable area (>0.7mm 2 ).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Microelectronic
A ±4A high-side current sensor with 25V input CM range and 0.9% gain error from -40°C to 85°C using an analog temperature compensation technique
No full textThis paper presents a fully integrated ±4A current sensor that supports a 25V input common-mode voltage range (CMVR) while operating from a single 1.5V supply. It consists of an on-chip metal shunt, a beyond-the-rails ADC [1] and a temperature-dependent voltage reference. The beyond-the-rails ADC facilitates high-side current sensing without the need for external resistive dividers or level shifters, thus reducing power consumption and system complexity. To compensate for the shunt's temperature dependence, the ADC employs a proportional-to-absolute-temperature (PTAT) reference voltage. Compared to digital temperature compensation schemes [2,3], this analog scheme eliminates the need for a temperature sensor, a band-gap voltage reference and calibration logic. As a result, the current sensor draws only 10.9μA and is 10x more energy efficient than [2]. Over a ±4A range, and after a one-point trim, the sensor exhibits a 0.9% (max) gain error from -40°C to 85°C and a 0.05% gain error at room temperature. The former is comparable with that of other fully-integrated current sensors [2-4], while the latter represents the state-of-the-art.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
A phase-domain readout circuit for a CMOS-compatible thermal-conductivity-based carbon dioxide sensor
No full textThe measurement of carbon-dioxide (CO2) concentration is very important in home and building automation, e.g. to control ventilation in energy-efficient buildings. This application requires compact, low-cost sensors that can measure CO2 concentration with a resolution of <200 ppm over a 2500ppm range. Conventional optical (NDIR-based) CO2 sensors require components that are CMOS-incompatible, difficult to miniaturize and power-hungry [1]. Due to their CMOS compatibility, thermal-conductivity-based sensors are an attractive alternative [2,3]. They exploit the fact that the thermal conductivity (TC) of CO2 is lower than that of the other constituents of air, so that CO2 concentration can be indirectly measured via the heat loss of a hot wire to ambient. However, this approach requires the detection of very small changes in TC (0.25 ppm per ppm CO2 [3]).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
Author Correction: Imaging-based representation and stratification of intra-tumor heterogeneity via tree-edit distance
No full textMartina Sollini and Paola Anna Erba were omitted from the author list in the original version of this Article. The Author Contributions section now reads: “L.C. conceived the pipeline, set up the case study, analysed the results, prepared the figures, and wrote the manuscript. M.P. formulated and tuned the pruned tree edit distance, provided the mathematical proofs and the simulation study, and wrote the manuscript. A.R. contributed to implement the patient representation pipeline. M.S. segmented the Prostate Cancer lesions and extracted the radiomic features for all patients in the case study. P.A.E collected the data and enrolled the patients in the clinical study. F.I. supervised the analyses and the conception of the pipeline. L.C., M.P., A.R. and F.I. reviewed and approved the manuscript.” The original Article and accompanying Supplementary Information file have been corrected.</p
Integration of drinking water treatment plant process models and emulated process automation software
No full textThe objective of this research is to limit the risks of fully automated operation of drinking water treatment plants and to improve their operation by using an integrated system of process models and emulated process automation software. This thesis contains the design of such an integrated system. The use of the system is investigated in the three identified applications, i) optimization of process control, ii) training of operation supervisors and iii) virtual commissioning of process automation software.Water ManagementCivil Engineering and Geoscience
Discolouration loose deposits in distribution systems: Composition, behaviour and practical aspects
No full textThe main objective of the thesis is to contribute to a better understanding of the possible origins and development processes underlying tap water discolouration. With that purpose, qualitative and practical approaches were used for collecting loose deposits samples from distribution networks, i.e., methodologies that may be used together with daily routine procedures by the water companies to prevent and interpret loose deposits accumulation. To investigate the origins of loose deposits, samples were subjected to physical?chemical characterisation, not only for their typical components (Fe, VS), but also for some organic constituents (i.e., EPS). To study loose deposits behaviour, loose deposits observations were followed by stereoscope and microscopy visualizations, as well as turbidity decrease measurements. Studies on loose deposits build?up were assessed with pilot scale experiments, for better knowledge on the loose deposits formation processes taking place at drinking water distribution systems. The microbiological relevance of discolouration loose deposits was also evaluated, including the possible role of bacteria in loose deposits accumulation, in order to appraise the possible effects on water quality upon loose deposits resuspension. Thus, this thesis aims to improve knowledge on the “whys” and “hows” of discolouration events in drinking water distribution systems. More specifically, emphasis was given to understand how such light particulates may accumulate and resist to the shear stresses occurring in drinking water distribution systems, before loose deposits resuspend at one time and cause tap water discolouration.Water ManagementCivil Engineering and Geoscience
Micro-pollutant removal from wastewater treatment plant effluent by activated carbon
No full textIn the recent years, the removal of micro-pollutants from treated wastewater has been highly advocated throughout Europe and the rest of the world. The relevant regulations and the suitable techniques have been proposed accordingly, which promoted the innovation of the conventional wastewater treatment plants (WWTPs). Activated carbon adsorption and advanced oxidation are regarded as the most promising technologies to attenuate micro-pollutant concentration in the treated wastewater (i.e. the secondary effluent). In this thesis, activated carbon adsorption of micro-pollutants was systematically studied with respects to the adsorption competition mechanisms and the practical applications for advancing wastewater tertiary treatment. Different forms and types of activated carbons were adopted in the particular operational system, the associated adsorption competitions between target micro-pollutants and the background organic matter (BOM) were illustrated with the aid of various BOM separation methods. Moreover, for a better exploitation of the activated carbon adsorption capacity (i.e. when integrating into the existing WWTPs), the appropriate dosing location and the dosing approach have been identified, respectively. In literature, there were two well-established pathways for BOM interfering with the target micro-pollutant adsorption on activated carbon: site competition and pore blocking. To differentiate these two pathways and examine which BOM fraction contributes most to the competition; batch adsorption tests and rapid small-scale column tests (RSSCTs) were performed, and an strong-base anionic exchange resin (AER) was used to separate the BOM. Results revealed that the AER was not effective to remove the site competition organics which interfered mostly with the micro-pollutants in the batch isotherm tests. These site competition organics appeared to be hydrophobic, and have a low molecular weight character. Moreover, the powered activated carbon (PAC) with the highest amount of primary and secondary micropores was subjected to the least site competition, and was thus selected for the subsequent RSSCTs, where, site competition and pore blocking occurred concurrently. In contrast to the batch adsorption tests, the retarded micro-pollutant breakthrough after AER pre-treatment indicated the relevance of AER removed organics for interfering with micro-pollutant adsorption in the dynamic filtration. This can be attributed to a less pore blocking effect due to the reduced amounts of ‘humic substances’ and ‘building blocks’ in the BOM. During the operation of granular activated carbon (GAC) filter, the preloading of BOM is a normal phenomenon before GAC contacts with the target micro-pollutants, this leads to an occupation of the adsorption sites and/or makes adsorption sites in small pores practically unavailable to the target micro-pollutants. To understand the preloading effects from wastewater effluent organic matter (EfOM) on the subsequent micro-pollutant (e.g. pharmaceutically active compounds, PhACs) adsorption. EfOM were differentiated by a nanofiltration (NF) membrane into fractions with size similar to or higher than that of the investigated PhACs. These two size fractions were pre-adsorbed onto two GACs with different pore structures. Comparison of the PhAC adsorption isotherms between the fresh GACs and the preloaded GACs reflected a significant reduction in the PhAC adsorption capacity after EfOM preloading, while the EfOM fraction which was rejected by the NF had a negligible impact. This observation emphasized the importance of the NF-permeating, low molecular organics for a direct site competition with the PhACs. Regarding the GAC pore structure, the one with a broad pore size distribution including both micropores and mesopores was able to adsorb an higher amount of EfOM, thus causing a higher PhAC adsorption reduction on the preloaded GAC. Furthermore, the PhAC adsorption reduction were correlated to their molecular physicochemical properties. PhACs with positive charge were found to have a less adsorption reduction than the neutral and negatively charged PhACs, due to the electrostatic attraction with the preloaded GAC surface. Additionally, hydrophobic PhACs within each charge group were generally more resistant to the preloading effects. Concerning the change of the GAC characteristics by a continuous preloading of the influent organic matter, spent GACs treating surface water and groundwater over a full operational cycle were collected, respectively. Comparing to the groundwater-spent GAC, which had a loss of only the secondary micropores, the surface water-spent GAC exhibited pore volume reduction covering a wide size range, due to the higher organic carbon concentration and also a broad molecular weight distribution of the organic matter in surface water. Specially, the higher amount of low molecular weight organics in surface water resulted in a diminishing of the primary micropores. Micro-pollutant (atrazine) adsorption tests were conducted to evaluate the reuse potential of the two spent GACs (after pulverizing). It was found that in addition to the reduced adsorption sites, the heavily loaded organic matter on surface water-spent carbon decreased atrazine adsorption capacity and hindered the adsorption kinetics (in a demineralized water), likely due to the induced water adsorption and water cluster formation on the spent carbon surface. However, a less adsorption competition was observed for atrazine adsorption in an organic matrix (i.e. the wastewater secondary effluent) on the surface water-spent carbon, because of the repulsion of the like-charged organic matter. This implies the suitability of reusing the surface water-spent carbon into the treated wastewater for micro-pollutant removal. When applying activated carbon e.g. PAC into the wastewater treatment processes for micro-pollutant adsorption, a better dosing location needed to be selected. The primary effluent and secondary effluent of a WWTP were considered in this respect. Primary effluent generally has a higher micro-pollutant concentration than the secondary effluent, and was thus supposed to facilitate the micro-pollutant adsorption onto PAC, while secondary effluent has less BOM concentration and was expected to cause less adsorption competition. Results showed a negligible PhAC uptake in the primary effluent in contrast to a significant PhAC uptake in the secondary effluent by fresh PAC, and this was mainly due to the site competition induced by the low molecular and hydrophobic organics, which were largely present in the primary effluent as compared to the secondary effluent. Moreover, these competing organics were able to replace the pre-adsorbed micro-pollutants (e.g. the negatively charged PhACs) from the PAC which was used for secondary effluent treatment. As such, recycling the PAC used for tertiary treatment into the e.g. activated sludge tank might not help to improve the overall micro-pollutant adsorption. The (fresh) PAC was thus utilized for the secondary effluent treatment and was integrated into a dual media tertiary filter (instead of recirculating into the activated sludge tank). As a simple and economic approach, PAC was directly added and immobilized inside the tertiary filter bed. In comparison to the batch adsorption tests where PAC was suspended, the immobilized PAC inside the filter bed can offer a better micro-pollutant removal, due to a constant micro-pollutant concentration gradient under the dynamic filtration condition. Analogously, a constantly improved micro-pollutant removal was observed as the immobilized PAC amount increased in the filter during PAC continuous dosing. In addition to the approach how PAC was added, the profile how PAC was distributed inside the filter bed also played a role in the micro-pollutant breakthrough. By manipulating the filter effluent valve, different ‘pre-embedding’ velocities were achieved, which can propel the PAC to transport downwards to the filter end. A higher pre-embedding velocity served to create a more homogeneous PAC distribution inside the filter bed, consequently, prolonging the micro-pollutant (e.g. sulfamethoxazole) breakthrough.Water ManagementCivil Engineering and Geoscience
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