scholarly journals Effect of Amplitude on the Surface Dilational Visco-Elasticity of Protein Solutions

2018 ◽  
Vol 2 (4) ◽  
pp. 57 ◽  
Author(s):  
Volodymyr Kovalchuk ◽  
Eugene Aksenenko ◽  
Dmytro Trukhin ◽  
Alexander Makievski ◽  
Valentin Fainerman ◽  
...  
Keyword(s):  
Surface Area ◽  
Surface Concentration ◽  
Convective Transport ◽  
Protein Solutions ◽  
Fixed Frequency ◽  
Inertia Effects ◽  
Adsorbed Protein ◽  
Protein Molecules ◽  
Uniform Expansions ◽  
Β Lactoglobulin

Harmonic drop surface area oscillations are performed at a fixed frequency (0.1 Hz) to measure the dilational visco-elasticity for three proteins: β-casein (BCS), β-lactoglobulin (BLG), and human serum albumin (HSA). The surface area oscillations were performed with different amplitudes in order to find the origin of non-linearity effects. The analysis of data shows that the non-linearity in the equation of state—i.e., the relation between surface pressure and surface concentration of adsorbed protein molecules—is the main source of the amplitude effects on the apparent visco-elasticity, while perturbations due to non-uniform expansions and compressions of the surface layer, inertia effects leading to deviations of the drop profile from the Laplacian shape, or convective transport in the drop bulk are of less importance. While for the globular proteins, HSA and BLG the amplitude effects on the apparent visco-elasticity are rather large, for the non-globular protein BCS this effect is negligible in the studied range of up to 10% area deformation.

Zehn Jahre Messungen der Anzahl- und lungendeponierbaren Oberflächenkonzentration ultrafeiner Partikel im städtischen Hintergrund im Ruhrgebiet/Ten years of measurements of the number and lung deposited surface concentration of ultrafine particles in the urban background in the Ruhr Area

Gefahrstoffe ◽  
2020 ◽  
Vol 80 (01-02) ◽  
pp. 25-32
Author(s):  
C. Asbach ◽  
T. A. J. Kuhlbusch ◽  
U. Quass ◽  
H. Kaminski
Keyword(s):  
Surface Area ◽  
Ultrafine Particles ◽  
Surface Concentration ◽  
Scanning Mobility Particle Sizer ◽  
Urban Background ◽  
Ruhr Area ◽  
Nanoparticle Surface ◽  
Particle Sizer

Seit Anfang 2009 werden an einer städtischen Hintergrundmessstation in Mülheim-Styrum im westlichen Ruhrgebiet Anzahlkonzentration, Anzahlgrößenverteilung und lungendeponierbare Oberflächenkonzentration submikroner und ultrafeiner Partikel gemessen. Die dazu eingesetzten Messgeräte Scanning Mobility Particle Sizer (SMPS) und Nanoparticle Surface Area Monitor (NSAM) erwiesen sich als gut geeignet für derartige Messaufgaben. Insbesondere das NSAM ist sehr robust und zuverlässig und wird daher neben der Bestimmung der lungendeponierbaren Oberflächenkonzentration auch zur Funktionsüberwachung des SMPS verwendet. Die ultrafeinen Partikel an der Messstation stammen zu einem großen Teil von einer nahegelegenen Autobahn sowie diversen anderen Quellen in der näheren Umgebung. Der etwa 20 km südlich gelegene Flughafen Düsseldorf scheint keinen merklichen Einfluss zu haben. Eine Auswertung der Wochengänge zeigte überraschenderweise, dass in allen Jahren samstagnachts die im Wochenverlauf höchste Anzahlkonzentration von Partikeln >100 nm gemessen wurde. Während an allen anderen Wochentagen die mittleren Konzentrationen seit 2009 kontinuierlich gesunken sind, blieb die Höhe des Maximums in der Nacht von Samstag auf Sonntag nahezu konstant, was auf eine unveränderte, zeitlich sehr begrenzte Quelle hindeutet.

Microvascular pressure, surface area, and permeability in isolated hindquarters of SHR

1985 ◽  
Vol 249 (3) ◽  
pp. H498-H504
Author(s):  
R. J. Korthuis ◽  
C. R. Kerr ◽  
M. I. Townsley ◽  
A. E. Taylor
Keyword(s):  
Skeletal Muscle ◽  
Capillary Pressure ◽  
Surface Area ◽  
Convective Transport ◽  
Microvascular Permeability ◽  
Spontaneously Hypertensive ◽  
Pressure Surface ◽  
Total Plasma Protein ◽  
Wistar Kyoto ◽  
Osmotic Reflection Coefficient

The transvascular escape rate (TER) of labeled albumin is reported to increase in essential hypertension. However, the mechanism for this augmented rate of protein efflux is uncertain and may be related to increased microvascular permeability, surface area, and/or pressure. To determine the possible contributions of these mechanisms to increased TER of protein, the osmotic reflection coefficient for total plasma protein, capillary filtration coefficient, and effective capillary pressure were estimated in isolated hindquarters of age-matched (12-13 wk) spontaneously hypertensive (SHR), Wistar-Kyoto (WKY), and Wistar (WR) rats. Estimates of the reflection and filtration coefficients were not significantly different in SHR, WKY, and WR. However, capillary pressure was significantly greater in SHR than in normotensive controls. These results indicate that 1) skeletal muscle microvascular permeability and surface area are similar in SHR, WKY, and WR; 2) effective capillary pressure is greater in SHR than WKY or WR; and 3) if TER for protein is elevated in hypertensive skeletal muscle, the primary mechanism for this process may be increased convective transport of protein secondary to elevated microvascular hydrostatic pressure.

scholarly journals Prospects on the nano-plastic particles internalization and induction of cellular response in human keratinocytes

2020 ◽  
Author(s):  
Ponnusamy Manogaran Gopinath ◽  
Krishna Sundar Twayana ◽  
Palaniyandi Ravanan ◽  
John Thomas ◽  
Amitava Mukherjee ◽  
...  
Keyword(s):  
Cellular Response ◽  
Protein Corona ◽  
Human Keratinocytes ◽  
Premature Aging ◽  
Hacat Cells ◽  
Proliferation Inhibition ◽  
Cytotoxic Effects ◽  
Adsorbed Protein ◽  
Protein Molecules ◽  
Cell Growth And Proliferation

Abstract Background Today cosmetic usage becomes customary in both sexes to improve their appearance and increase societal visibility. In this study, we have isolated nano-sized plastic particles ranging between 30 to 300 nm from the commercial face-scrubs and investigated its effects on keratinocytes. Results Initially, nano-plastics adsorbed protein molecules and formed protein corona, thereby mimicked as protein aggregates, which then triggered the macropinocytosis activity. As a result, corrosion and degradation of plastic particles were observed. Concurrently, nano-plastics concentration-dependent cytotoxic, cytostatic, and cytoprotective activities were found in the keratinocytes. Additionally, a single dose of nano-plastics exposure resulted in the ROS mediated down-regulation of cell growth and proliferation inhibition followed by autophagy, finally, premature aging in HaCaT cells. Conclusion At the outset, this work provides insights into the nano-plastics concentration-dependent regulatory, cytoprotective, and cytotoxic effects in HaCaT cells. Further signifies the crucial need for new regulation in nano-plastics usage in cosmetics.

scholarly journals High Energy Radiation-Induced Aggregation of Plasma Proteins. Time Resolved Light Scattering Measurements

1980 ◽  
Vol 35 (2) ◽  
pp. 217-220 ◽  
Author(s):  
H. Kihara ◽  
W. Schnabel
Keyword(s):  
High Energy ◽  
Relative Increase ◽  
Protein Solutions ◽  
Oh Radicals ◽  
Time Resolved ◽  
Short Pulses ◽  
Radiation Chemical ◽  
Protein Molecules ◽  
Radiation Induced ◽  
Induced Aggregation

Abstract Human immunoglobulin (IgG), bovine fibrinogen and bovine serum albumin were irradiated at room temperature with short pulses (50 ns to 2 μs) of 16 MeV electrons in 0.2 M NaClO4 solution containing phosphate buffer (pH 7.5). In the presence of N2O the intensity of light (LSI) scattered by the protein solutions increased after the pulse indicating aggregation. The latter process originates from the attack of protein molecules by OH radicals (aggregation is impeded by t-butanol and augmented by N2O). Upon plotting the relative increase of LSI vs. log time (after the pulse) sigmoidally shaped curves were obtained.From these findings and results of optical absorption measurements the following is inferred: Aggregation occurs as a consequence of chemical alterations of the protein molecules induced by the attack by OH radicals. The transient species formed during and a few pis after the pulse are reacting within a period of several ms. At the end of this period the formation of aggregates starts. It is concluded that the primary radiation chemical process consists (among others) in the generation of nuclcation sites. The latter subsequently initiate aggregation processes.

Catalytic Activity and Surface Characterization Study of Pd Supported on Nanocrystalline and Polycrystalline CeO2

1999 ◽  
Vol 581 ◽  
Author(s):  
Gar B. Hoflund ◽  
Zhenhua Li ◽  
Timothy J. Campbell ◽  
William S. Epling ◽  
Horst W. Hahn
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Surface Concentration ◽  
Slow Step ◽  
Activity Increase ◽  
Area Basis ◽  
Surface Area Basis ◽  
Supported Pd

ABSTRACTThe catalytic activity of polycrystalline and nanocrystalline CeO2-supported Pd (Pd/pCeO2 and Pd/nCeO2) has been determined as a function of temperature and Pd loading. While the untreated nCeO2 support gives 50% methane conversion at 420°C, the untreated pCeO2 support exhibits little activity under the conditions examined due to its low surface area. A Pd loading of 5 wt% increases the activity of pCeO2 to 50% conversion at 260°C, while a 40 wt% Pd loading on nCeO2 exhibits a relatively smaller activity increase, yielding 50% conversion at 240°C. On a mass basis the 40 wt% Pd/nCeO2 catalyst is the most active tested in this study, but it is less active than the 5 wt% Pd/pCeO2 catalyst on a surface-area basis. Furthermore, the activity of the 40 wt% Pd/nCeO2 catalyst does not decrease during 100 hrs of exposure to CH4 and O2 at 250°C.X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS) have been used to characterize the surfaces of both bare supports and Pd-containing catalysts before and after exposure to reactor conditions. The XPS results reveal that the Pd surface concentration is more than an order of magnitude higher for 5 wt% Pd/pCeO2 than for 5 wt% Pd/nCeO2 due to the larger surface area of nCeO2 and that the 40 wt% Pd/nCeO2 catalyst has a lower Pd loading on a surface-area basis than the 5 wt% Pd/pCeO2 catalyst. Most of the supported Pd is in the form of PdO, but higher PdO2/PdO ratios are observed for both CeO2 supports compared to Pd supported on ZrO2 or CO3O4. Furthermore, a significant amount of metallic Pd forms on Pd/nCeO2 but not on Pd/pCeO2 during reaction. The nanocrystalline and polycrystalline CeO2 behave differently chemically which is consistent with the fact that the nanocrystalline catalysts are less active on a surface-area basis. Accumulation of H20 on the Pd/pCeO2 surface during reaction is significant but not on the Pd/nCeO2 surface. This suggests that the rate limiting step may be H2O desorption on Pd/pCeO2 while for Pd on nCeO2 adsorption of methane appears to be the slow step. The ISS data indicate that the outermost atomic layer of Pd/nCeO2 consists mostly of O and C, which is not the case for Pd/pCeO2. Site blockage by these species may also contribute to the lower activity on a surface-area basis of Pd/nCeO2 compared to Pd/pCeO2.

The non-stoichiometry of pink zinc oxide

1975 ◽  
Vol 28 (2) ◽  
pp. 229
Author(s):  
VJ Norman
Keyword(s):  
Carbon Dioxide ◽  
Zinc Oxide ◽  
Specific Surface ◽  
Nitrogen Content ◽  
Surface Area ◽  
Total Nitrogen ◽  
Reactive Oxygen ◽  
Surface Concentration ◽  
Controlled Environment ◽  
Interstitial Zinc

A highly coloured pink zinc oxide, having a total nitrogen content of 0.054%, has been prepared by heating white zinc oxide and ammonium carbamate in an atmosphere of ammonia and carbon dioxide at 200�. The preparation results in a marked increase in the specific surface area of the zinc oxide. ��� The non-stoichiometry of the pink zinc oxide has been determined, and it is shown that the amount of reactive oxygen chemisorbed on the surface increases with time. The maximum chemisorption amounted to 52 p.p.m. by weight (1.1 x 1025 ion m-3) after exposure for 35 days in a controlled environment. The surface concentration of interstitial zinc has been estimated indirectly from the reactive oxygen results. The concentration of the non-stoichiometric species in pink zinc oxide is more than an order higher than that of the white zinc oxide from which it was prepared. The results support the mechanism tentatively proposed by previous workers for the incorporation of nitrogen in zinc oxide.

scholarly journals Thermal Denaturation of Interfacial Protein Layers

2002 ◽  
Vol 55 (7) ◽  
pp. 449 ◽  
Author(s):  
S. A. Holt ◽  
M. J. Henderson ◽  
J. W. White
Keyword(s):  
Room Temperature ◽  
Thermal Denaturation ◽  
Scattering Length ◽  
Neutron Reflectivity ◽  
Protein Layer ◽  
Adsorbed Protein ◽  
Air Water Interface ◽  
Two State Model ◽  
First Time ◽  
Β Lactoglobulin

We report for the first time the structural measurements at nanometre resolution of the denaturation of β-lactoglobulin and lysozyme at an air–water interface using the technique of neutron reflectivity. The incipient denaturation shown previously[1] for myogloblin is also studied for these molecules at room temperature, and denaturation is provoked by increasing the temperature of the solutions progressively to 75°C. The change in the adsorbed protein layer thickness, its scattering length density and density distribution perpendicular to the surface as a function of increased temperature are reported and the data analysed in terms of a two-state model for the denaturation process. These measurements are relevant to an understanding of the way in which proteins at interfaces act as templates, for example, in biomineralization.

scholarly journals Simulation of radon-222 with the GEOS-Chem global model: Emissions, seasonality, and convective transport

2020 ◽  
Author(s):  
Bo Zhang ◽  
Hongyu Liu ◽  
James H. Crawford ◽  
Gao Chen ◽  
T. Duncan Fairlie ◽  
...  
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Lower Troposphere ◽  
Chemical Transport ◽  
Surface Concentration ◽  
Vertical Gradient ◽  
Convective Transport ◽  
Chemical Transport Model ◽  
Earth Observing System ◽  
Land Surfaces

Abstract. Radon-222 (222Rn) is a short-lived radioactive gas naturally emitted from land surfaces, and has long been used to assess convective transport in atmospheric models. In this study, we simulate 222Rn using the GEOS-Chem chemical transport model to improve our understanding of 222Rn emissions and surface concentration seasonality, and characterize convective transport associated with two Goddard Earth Observing System (GEOS) meteorological products, MERRA and GEOS-FP. We evaluate four global 222Rn emission scenarios by comparing model results with observations at 51 surface sites. The default emission scenario in GEOS-Chem yields a moderate agreement with surface observations globally ( 80 % data within a factor of 2), and reasonable agreement in Asia (close to 70 %). Further constraints on 222Rn emissions would require additional concentration and emission flux observations in the central U.S., Canada, Africa, and Asia. We also compare and assess convective transport in model simulations driven by MERRA and GEOS-FP using observed 222Rn vertical profiles in northern mid-latitude summer, and from three short-term airborne campaigns. While simulations with both GEOS products are able to capture the observed vertical gradient of 222Rn concentrations in the lower troposphere (0–4 km), neither correctly represents the level of convective detrainment, resulting in biases in the middle and upper troposphere. Compared with GEOS-FP, MERRA leads to stronger convective transport of 222Rn, which is partially compensated by its weaker large-scale vertical advection, resulting in similar global vertical distributions of 222Rn concentrations between the two simulations. This has important implications for using chemical transport models to interpret the transport of other trace species when these GEOS products are used as driving meteorology.

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