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Derek Marsh - One of the best experts on this subject based on the ideXlab platform.

  • Water Penetration Profile at the protein-lipid interface in Na,K-ATPase membranes.
    Biophysical journal, 2014
    Co-Authors: Rosa Bartucci, Rita Guzzi, Mikael Esmann, Derek Marsh
    Abstract:

    The affinity of ionized fatty acids for the Na,K-ATPase is used to determine the transmembrane Profile of water Penetration at the protein-lipid interface. The standardized intensity of the electron spin echo envelope modulation (ESEEM) from 2H-hyperfine interaction with D2O is determined for stearic acid, n-SASL, spin-labeled systematically at the C-n atoms throughout the chain. In both native Na,K-ATPase membranes from shark salt gland and bilayers of the extracted membrane lipids, the D2O-ESEEM intensities of fully charged n-SASL decrease progressively with position down the fatty acid chain toward the terminal methyl group. Whereas the D2O intensities decrease sharply at the n = 9 position in the lipid bilayers, a much broader transition region in the range n = 6 to 10 is found with Na,K-ATPase membranes. Correction for the bilayer population in the membranes yields the intrinsic D2O-intensity Profile at the protein-lipid interface. For positions at either end of the chains, the D2O concentrations at the protein interface are greater than in the lipid bilayer, and the positional Profile is much broader. This reveals the higher polarity, and consequently higher intramembrane water concentration, at the protein-lipid interface. In particular, there is a significant water concentration adjacent to the protein at the membrane midplane, unlike the situation in the bilayer regions of this cholesterol-rich membrane. Experiments with protonated fatty acid and phosphatidylcholine spin labels, both of which have a considerably lower affinity for the Na,K-ATPase, confirm these results.

  • Membrane Penetration of nitric oxide and its donor S-nitroso-N- acetylpenicillamine: A spin-label electron paramagnetic resonance spectroscopic study
    Biochimica et Biophysica Acta, 2004
    Co-Authors: Saviana Nedeianu, Tibor Páli, Derek Marsh
    Abstract:

    S-nitroso-N-acetylpenicillamine (SNAP) is a pharmacological agent with diverse biological effects that are mainly attributable to its favorable characteristics as a nitric oxide (NO)-evolving agent. It is found that SNAP incorporates readily into dimyristoyl phosphatidylcholine (DMPC) bilayer membranes; and an approximate Penetration Profile was obtained from the depth dependence of the perturbation that it exerts on spin-labeled lipid chains. The Profile of SNAP locates it deep in the hydrophobic core of both fluid- and gelphase membranes. The spin relaxation enhancement of spin-labeled phospholipids with nitroxide group located at different depths in DMPC membranes was determined for nitric oxide (NO) and molecular oxygen (O2), at close to atomic spatial resolution. The relaxation enhancement, which is proportional to the corresponding vertical membrane Profile of the concentration-diffusion product, was measured in the gel and fluid phases of the lipid bilayer. No significant membrane Penetration was observed in the gel phase for the two water-dissolved gases. In the fluid phase, the transmembrane Profiles of NO and O2 are similar and could be well described by a sigmoidal function with a maximum in the center of the bilayer, but that of NO is less steep and is shifted toward the center of the membrane, relative to that of O2. These differences can be attributed mainly to the difference in hydrophobicity between the two gases and the presence of the donor in the NO experiments. The biological implications of the above results are discussed. D 2004 Elsevier B.V. All rights reserved.

  • Membrane water-Penetration Profiles from spin labels
    European biophysics journal : EBJ, 2002
    Co-Authors: Derek Marsh
    Abstract:

    Spin label hyperfine splittings in mixtures of protic and aprotic solvents are used to obtain association constants K A,h for hydrogen bonding to oxazolidine nitroxides. With the Onsager approach to account for the variation in local dielectric constant, these results are used to determine the effective Penetration Profile of water into fluid phospholipid membranes, from recent electron paramagnetic resonance (EPR) studies on phospholipids spin-labelled systematically down the sn-2 chain. Water Penetration is appreciable, depends on chain unsaturation, and is strongly affected by cholesterol.

Jürgen Lademann - One of the best experts on this subject based on the ideXlab platform.

  • analysis of human and porcine skin in vivo ex vivo for Penetration of selected oils by confocal raman microscopy
    Skin Pharmacology and Physiology, 2015
    Co-Authors: Chunsik Choe, Jürgen Lademann, Maxim E. Darvin
    Abstract:

    Background: The subject of oil Penetration into the skin is controversially discussed in the scientific literature. Methods: Confocal Raman microscopy was used for analyzing oil Penetration into the skin. The following methods were applied in the study: methods based on tracking specific peaks (method 1), the nonrestricted multiple least square fit (method 2), analyzing the lipid-to-keratin peak ratio using the perpendicular drop-down cutoff procedure (method 3), and the Gaussian function-based deconvolution procedure (method 4). Results: The results obtained using methods 1, 2 and 4 show that the investigated oils do not penetrate deeper than 11 µm into human and porcine skin. Petrolatum has a prominent swelling effect on the stratum corneum (32% in vivo, 28% ex vivo), while the other oils exhibit no significant swelling effect. By using method 3, the Penetration Profile of oils, and especially of petrolatum, into the skin was interpreted incorrectly for various reasons that are addressed herein below. Conclusion: Predominantly remaining in the uppermost corneocyte layers of the stratum corneum, topically applied oils do not reach the viable cells of the stratum spinosum. To exclude any possible mistakes when using the lipid-keratin Raman peak (2,820-3,030 cm-1), the Penetration analysis should be performed using the Gaussian function-based deconvolution procedure.

  • Gaussian-function-based deconvolution method to determine the Penetration ability of petrolatum oil into in vivo human skin using confocal Raman microscopy
    Laser Physics, 2014
    Co-Authors: Chunsik Choe, Jürgen Lademann, Maxim E. Darvin
    Abstract:

    Human skin pre-treated with petrolatum was analyzed in vivo using confocal Raman microscopy in order to determine the Penetration depth of the oil into the skin. The broad Raman peak (2820–3030 cm−1) measured in vivo on human skin in the high wavenumber region exhibits two prominent main Raman peaks at 2880 cm−1 and 2935 cm−1 that originated from cutaneous lipids and keratin and two main peak shoulders at 2850 cm−1 and 2980 cm−1 that originated from lipids and keratin, respectively. Topical application of petrolatum oil onto the skin gives rise to an increase of the intensity of the broad lipid–keratin Raman peak (2820–3030 cm−1). Herewith, not only the intensity of the lipid part but also of the keratin part is increased, making the normalization to keratin and the determination of the petrolatum Penetration Profile erroneous. To solve this problem, the Gaussian-function-based deconvolution method is introduced in analyzing the Raman spectrum of the lipid–keratin peak and the least square method is applied for analyzing the petrolatum Penetration Profile. Results obtained in vivo show that the petrolatum oil does not penetrate deeper than 10 µm into intact human skin.

  • Reconstruction of stratum corneum Profile of porcine ear skin after tape stripping using UV/VIS spectroscopy
    Diagnostic Optical Spectroscopy in Biomedicine IV, 2007
    Co-Authors: Alexey Popov, Jürgen Lademann, Alexander V. Priezzhev, Risto Myllylä
    Abstract:

    Stratum corneum (horny layer) is a superficial skin layer consisting of dead cells. To reveal in-depth Penetration Profiles of substances topically applied onto skin surface, a minimally invasive method called tape stripping is widely used. It introduces consecutive removal of micrometer-thick cell layers of stratum corneum from the same treated skin area using an adhesive tape. Prerequisite to the substance Penetration Profile is the reconstruction of the removed stratum corneum by analyzing the amount of corneocytes (cells of stratum corneum from) stuck to each tape strip. Before application in vivo on humans, porcine skin is often used for such kind of studies. In this paper, we present results of the experiments with porcine skin in vitro (ears of freshly slaughtered pigs) and compare them with those carried out on humans in vivo (flexor forearm) taken from references. As we proved experimentally, there is a linear dependence between the absorbance (equals to logarithm of inverse transmittance) and thickness of the corneocytes on tape strips for all wavelength of the investigated region (300-1050 nm). Dependence of the cumulative absorbance of removed stratum corneum on tape strip number can be satisfactory fitted by an exponential function. This relationship allows evaluation of the relative share of the removed stratum corneum without complete removal of the layer. All the obtained results correlate well with those obtained on humans.

  • Determination of Penetration Profiles of topically applied substances by means of tape stripping and optical spectroscopy: UV filter substance in sunscreens.
    Journal of biomedical optics, 2005
    Co-Authors: Hans-ju¨rgen Weigmann, Ute Jacobi, Christina Antoniou, George N. Tsikrikas, Volker Wendel, Claudius Rapp, Heiner Gers-barlag, Wolfram Sterry, Jürgen Lademann
    Abstract:

    Penetration Profiles of topically applied drugs and cosmetic products provide important information on their efficacy. The application of tape stripping in combination with UV/VIS spectroscopy is checked to determine the local position of topically applied substances inside the stratum corneum, the Penetration Profile. The amount of corneocytes removed with each tape strip is quantified via the particle-dependent absorption, the pseudoabsorption, in the visible spectral range. The concentration of a typical UV filter substance, 4-methylbenzylidene camphor, is determined by optical spectroscopy using the tape strips removed originally. In this case, a time-dependent increase in the absorbance must be taken into account. Laser scanning microscopic investigations confirm that the nonhomogeneous distribution of the filter substance, on the strips, can explain this spectroscopic behavior. When reaching a homogeneous distribution, the UV spectroscopic signal reflects the correct concentration. These spectroscopic values are compared with high performance liquid chromatography (HPLC) data. The values obtained with both methods for the concentrations of 4-methylbenzylidene camphor are in good agreement. The data obtained are used to illustrate the determination of a Penetration Profile of a UV filter substance. The results demonstrate that the described protocol is well suited to characterize, in a simple manner, topically applied substances that have a characteristic UV/VIS absorption band.

  • Penetration Profile of Microspheres in Follicular Targeting of Terminal Hair Follicles
    The Journal of investigative dermatology, 2004
    Co-Authors: R. Toll, U. Jacobi, Heike Richter, Jürgen Lademann, H. Schaefer, Ulrike Blume-peytavi
    Abstract:

    The transfollicular administration of pharmacologically active molecules is of current therapeutic interest, mainly with regard to delivery to specific sites of the hair follicle (HF) and the reduction of hepatic metabolism and systemic toxicity. HF are privileged pathways for specific molecules depending on formulations, which enter faster into these shunts than through the stratum corneum. The aim was to optimize the delivery of fluorescent microspheres into the HF, thereby, developing a standardized protocol for follicular targeting with microspheres. The number of HF showing Penetration, as well as the depth of Penetration, was determined. Freshly excised skin samples with terminal HF were divided into groups, with or without prior treatment with cyanoacrylate skin surface stripping-technique (CSSS). Thereafter microspheres at a size of 0.75–6.0 μm were applied according to the developed standardized protocol. Skin biopsies were obtained, shock-frozen, and sectioned in 5 μm slices. We demonstrated a selective Penetration route of the microspheres into the HF. Optimal microsphere size proved to be approximately 1.5 μm, with a 55% rate of all HF, and with a maximum Penetration depth of >2300 μm. Without previous CSSS treatment of the skin, the transfollicular microsphere Penetration was below 27% with a maximum Penetration depth of 1000 μm. Thus, the basis for follicular targeting of essential structures containing stem cells for keratinocytes, melanocytes, and mast cells has been laid.

Qiao Huang - One of the best experts on this subject based on the ideXlab platform.

  • Optimal sensor network design for multi-scale, time-varying differential algebraic equation systems: Application to an entrained-flow gasifier refractory brick
    Computers & Chemical Engineering, 2020
    Co-Authors: Qiao Huang, Debangsu Bhattacharyya
    Abstract:

    Abstract An algorithm for optimal sensor network design for multi-scale, time-varying differential algebraic equation systems with non-separable dynamics is presented. As the process is time-varying, an integral normalized posterior error covariance of a multi-scale filter is minimized to obtain the optimal sensor locations. For reducing the computational cost, an adaptive sampling rate approach is considered for the slowly-varying variables. The algorithm is applied to a smart refractory brick with embedded sensors as part of an entrained-flow gasifier. Thermistors and interdigital capacitors are considered as candidate measurement technologies for estimating temperature and slag Penetration Profile along the gasifier wall. When the optimal set of sensors obtained from the algorithm is used for estimating temperature and slag Penetration Profiles in a multi-scale Kalman filter framework, satisfactory estimates are obtained despite high measurement noise and model mismatch.

  • estimations of gasifier wall temperature and extent of slag Penetration using a refractory brick with embedded sensors
    Industrial & Engineering Chemistry Research, 2017
    Co-Authors: Qiao Huang, Prokash Paul, Debangsu Bhattacharyya, Rajalekshmi C Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
    Abstract:

    The short service life of refractory lining in a slagging gasifier in the integrated gasification combined cycle results in low availability and high operating cost. For longer life of the refractory lining, estimation of slag Penetration length and monitoring of wall temperature are important. In this paper, we have investigated two types of embedded sensors in the refractory lining of gasifier, namely, thermistor and interdigital capacitor, to estimate the wall temperature Profile and extent of slag Penetration. Conventional correlation-based approaches are not satisfactory for estimating outputs of interest from the raw sensor data for these systems because of high temperature gradient along the sensor as well as temporal change in the refractory properties due to slag Penetration. Therefore, a thermal model of refractory brick, slag Penetration model, and models of the embedded sensors are developed and used to estimate temperature and slag Penetration Profile by using linear and nonlinear estimators.

  • Estimations of Gasifier Wall Temperature and Extent of Slag Penetration Using a Refractory Brick with Embedded Sensors
    2017
    Co-Authors: Qiao Huang, Prokash Paul, Debangsu Bhattacharyya, Rajalekshmi C Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
    Abstract:

    The short service life of refractory lining in a slagging gasifier in the integrated gasification combined cycle results in low availability and high operating cost. For longer life of the refractory lining, estimation of slag Penetration length and monitoring of wall temperature are important. In this paper, we have investigated two types of embedded sensors in the refractory lining of gasifier, namely, thermistor and interdigital capacitor, to estimate the wall temperature Profile and extent of slag Penetration. Conventional correlation-based approaches are not satisfactory for estimating outputs of interest from the raw sensor data for these systems because of high temperature gradient along the sensor as well as temporal change in the refractory properties due to slag Penetration. Therefore, a thermal model of refractory brick, slag Penetration model, and models of the embedded sensors are developed and used to estimate temperature and slag Penetration Profile by using linear and nonlinear estimators

Debangsu Bhattacharyya - One of the best experts on this subject based on the ideXlab platform.

  • Optimal sensor network design for multi-scale, time-varying differential algebraic equation systems: Application to an entrained-flow gasifier refractory brick
    Computers & Chemical Engineering, 2020
    Co-Authors: Qiao Huang, Debangsu Bhattacharyya
    Abstract:

    Abstract An algorithm for optimal sensor network design for multi-scale, time-varying differential algebraic equation systems with non-separable dynamics is presented. As the process is time-varying, an integral normalized posterior error covariance of a multi-scale filter is minimized to obtain the optimal sensor locations. For reducing the computational cost, an adaptive sampling rate approach is considered for the slowly-varying variables. The algorithm is applied to a smart refractory brick with embedded sensors as part of an entrained-flow gasifier. Thermistors and interdigital capacitors are considered as candidate measurement technologies for estimating temperature and slag Penetration Profile along the gasifier wall. When the optimal set of sensors obtained from the algorithm is used for estimating temperature and slag Penetration Profiles in a multi-scale Kalman filter framework, satisfactory estimates are obtained despite high measurement noise and model mismatch.

  • estimations of gasifier wall temperature and extent of slag Penetration using a refractory brick with embedded sensors
    Industrial & Engineering Chemistry Research, 2017
    Co-Authors: Qiao Huang, Prokash Paul, Debangsu Bhattacharyya, Rajalekshmi C Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
    Abstract:

    The short service life of refractory lining in a slagging gasifier in the integrated gasification combined cycle results in low availability and high operating cost. For longer life of the refractory lining, estimation of slag Penetration length and monitoring of wall temperature are important. In this paper, we have investigated two types of embedded sensors in the refractory lining of gasifier, namely, thermistor and interdigital capacitor, to estimate the wall temperature Profile and extent of slag Penetration. Conventional correlation-based approaches are not satisfactory for estimating outputs of interest from the raw sensor data for these systems because of high temperature gradient along the sensor as well as temporal change in the refractory properties due to slag Penetration. Therefore, a thermal model of refractory brick, slag Penetration model, and models of the embedded sensors are developed and used to estimate temperature and slag Penetration Profile by using linear and nonlinear estimators.

  • Estimations of Gasifier Wall Temperature and Extent of Slag Penetration Using a Refractory Brick with Embedded Sensors
    2017
    Co-Authors: Qiao Huang, Prokash Paul, Debangsu Bhattacharyya, Rajalekshmi C Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
    Abstract:

    The short service life of refractory lining in a slagging gasifier in the integrated gasification combined cycle results in low availability and high operating cost. For longer life of the refractory lining, estimation of slag Penetration length and monitoring of wall temperature are important. In this paper, we have investigated two types of embedded sensors in the refractory lining of gasifier, namely, thermistor and interdigital capacitor, to estimate the wall temperature Profile and extent of slag Penetration. Conventional correlation-based approaches are not satisfactory for estimating outputs of interest from the raw sensor data for these systems because of high temperature gradient along the sensor as well as temporal change in the refractory properties due to slag Penetration. Therefore, a thermal model of refractory brick, slag Penetration model, and models of the embedded sensors are developed and used to estimate temperature and slag Penetration Profile by using linear and nonlinear estimators

Edward M. Sabolsky - One of the best experts on this subject based on the ideXlab platform.

  • estimations of gasifier wall temperature and extent of slag Penetration using a refractory brick with embedded sensors
    Industrial & Engineering Chemistry Research, 2017
    Co-Authors: Qiao Huang, Prokash Paul, Debangsu Bhattacharyya, Rajalekshmi C Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
    Abstract:

    The short service life of refractory lining in a slagging gasifier in the integrated gasification combined cycle results in low availability and high operating cost. For longer life of the refractory lining, estimation of slag Penetration length and monitoring of wall temperature are important. In this paper, we have investigated two types of embedded sensors in the refractory lining of gasifier, namely, thermistor and interdigital capacitor, to estimate the wall temperature Profile and extent of slag Penetration. Conventional correlation-based approaches are not satisfactory for estimating outputs of interest from the raw sensor data for these systems because of high temperature gradient along the sensor as well as temporal change in the refractory properties due to slag Penetration. Therefore, a thermal model of refractory brick, slag Penetration model, and models of the embedded sensors are developed and used to estimate temperature and slag Penetration Profile by using linear and nonlinear estimators.

  • Estimations of Gasifier Wall Temperature and Extent of Slag Penetration Using a Refractory Brick with Embedded Sensors
    2017
    Co-Authors: Qiao Huang, Prokash Paul, Debangsu Bhattacharyya, Rajalekshmi C Pillai, Katarzyna Sabolsky, Edward M. Sabolsky
    Abstract:

    The short service life of refractory lining in a slagging gasifier in the integrated gasification combined cycle results in low availability and high operating cost. For longer life of the refractory lining, estimation of slag Penetration length and monitoring of wall temperature are important. In this paper, we have investigated two types of embedded sensors in the refractory lining of gasifier, namely, thermistor and interdigital capacitor, to estimate the wall temperature Profile and extent of slag Penetration. Conventional correlation-based approaches are not satisfactory for estimating outputs of interest from the raw sensor data for these systems because of high temperature gradient along the sensor as well as temporal change in the refractory properties due to slag Penetration. Therefore, a thermal model of refractory brick, slag Penetration model, and models of the embedded sensors are developed and used to estimate temperature and slag Penetration Profile by using linear and nonlinear estimators