H Resurface and Hot H Promoted H2 Recombination on Ni(111): Effects of Arrangement, Surface Coverage, and Lattice Motion

The microstructure of polyacrylonitrile (PAN) beads for affinity chromatography bioseparations was studied by TEM of stained ultramicrotomed thin-sections. Microstructural aspects such as overall pore size distribution, the distribution of pores within the beads, and surface coverage of functionalized beads affect performance properties. Stereological methods are used to quantify the internal structure of these chromatographic supports. Details of the process for making the PAN beads are given elsewhere. TEM specimens were obtained by vacuum impregnation with a low-viscosity epoxy and sectioning with a diamond knife. The beads can be observed unstained. However, different surface functionalities can be made evident by selective staining. Amide surface coverage was studied by staining in vapor of a 0.5.% RuO4 aqueous solution for 1 h. RuO4 does not stain PAN but stains, amongst many others, polymers containing an amide moiety.

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Further Evidence that Glycoprotein IIb-IIIa Mediates Platelet Spreading on Subendothelium

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647484 ◽

1991 ◽

Vol 65 (02) ◽

pp. 202-205 ◽

Cited By ~ 37

Author(s):

Harvey J Weiss ◽

Vincet T Turitto ◽

Hans R Baumgartner

Keyword(s):

Platelet Adhesion ◽

Surface Coverage ◽

Rabbit Aorta ◽

Conclusive Evidence ◽

Initial Contact ◽

Single Exposure ◽

Vessel Segment ◽

Multiple Exposures ◽

Wall Interaction ◽

Platelet Spreading

SummaryIn order to explore further the mechanism by which glycoprotein GPIIb-IIIa promotes platelet vessel wall interaction, platelet adhesion to subendothelium was studied in an annular chamber in which subendothelium from rabbit aorta was exposed at a shear rate of 2,600 s−1 to blood from patients with thrombasthenia. Perfusions were conducted for each of 5 exposure times (1 ,2,3, 5 and 10 min), and the percent surface coverage of the vessel segment with platelets in the contact (C) and spread (S) stage was determined. Increased values of platelet contact (C) were obtained in thrombasthenia at all exposure times; this finding is consistent with a defect in platelet spreadirg, based on a previously described kinetic model of platelet attachment to subendothelium. According to this model of attachment, increased values of platelet contact (C) at a single exposure time may be indicative of either a defect in spreading (S) or initial contact (C), but multiple exposures will result in increased contact only for defects which are related to defectiye platelet spreading (s).The results obtained over a broad range of exposure times provide more conclusive evidence that GPIIb-IIIa mediates platelet spreading than those previously obtained at single exposure times.

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Automated Microdensitometry And Protein Assays As Measures For Platelet Adhesion And Aggregation On Collagen Coated Slides Under Controlled Flow Conditions

10.1055/s-0038-1665758 ◽

1979 ◽

Author(s):

R Muggli ◽

H Baumgartner ◽

Th Tschopp

Keyword(s):

Surface Coverage ◽

Platelet Surface ◽

En Face ◽

Uncoated Surface ◽

Unit Surface ◽

Perfusion Time ◽

Flowing Blood ◽

Controlled Flow ◽

Protein Assays ◽

Microscope Slides

Microscope slides were homogeneously coated over a length of 2 cm with a mixture of soluble and fibrillar collagen and exposed at 37°C and under laminar flow to citrated whole rabbit blood at a flow-rate of 100 ml/min. Surface coverage with platelets (adhesion) and platelet accumulations higher than about 5 μm in height (aggregation) were determined by automated microdensitometry of fuchsine stained ‘en face’ preparations. The platelet mass per unit surface was measured with a modified Lowry technique whose sensitivity was equivalent to 5×l05platelets. Platelet number, amount of protein and surface coverage with platelet accumulations correlated. After a perfusion time of 10 min thrombi up to 30 μm in height and oriented in the direction of flow had developed on the collagen coated area. Surface coverage with platelets was 75% and the amount of deposited protein 1.4 μg/mm2(2×l06platelets/mm2). On the uncoated surface single platelets predominated; the surface coverage was 20% and the density of platelets 8×104/mm2. Acetyl- salicylic acid at 100 μm decreased platelet aggregation by about 80% without affecting adhesion.The new parallel plate perfusion system offers rapid quantitation of platelet-surface and platelet-platelet interaction after exposure to flowing blood and iftay also be diagnostically useful.

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The Nature of Chemisorbed CO2 in Zeolite A

10.26434/chemrxiv.7422815 ◽

2019 ◽

Author(s):

Przemyslaw Rzepka ◽

Zoltán Bacsik ◽

Andrew J. Pell ◽

Niklas Hedin ◽

Aleksander Jaworski

Keyword(s):

Solid State ◽

Ir Spectroscopy ◽

Quantum Chemical Calculations ◽

Quantum Chemical ◽

Surface Coverage ◽

Gas Mixtures ◽

Mas Nmr ◽

Significant Fraction ◽

Zeolite A

Formation of CO32- and HCO3- species without participation of the framework oxygen atoms upon chemisorption of CO2 in zeolite |Na12|-A is revealed. The transfer of O and H atoms is very likely to have proceeded via the involvement of residual H2O or acid groups. A combined study by solid-state 13C MAS NMR, quantum chemical calculations, and in situ IR spectroscopy showed that the chemisorption mainly occurred by the formation of HCO3-. However, at a low surface coverage of physisorbed and acidic CO2, a significant fraction of the HCO3- was deprotonated and transformed into CO32-. We expect that similar chemisorption of CO2 would occur for low-silica zeolites and other basic silicates of interest for the capture of CO2 from gas mixtures.

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Work function studies of propylene, acetylene, hydrogen and nitrogen chemisorption on molybdenum

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19822996 ◽

1982 ◽

Vol 47 (11) ◽

pp. 2996-3003

Author(s):

Zdeněk Bastl

Keyword(s):

Work Function ◽

Surface Topography ◽

Surface Coverage ◽

Dissociative Chemisorption ◽

Complete Coverage ◽

Surface Sites ◽

Function Change ◽

Work Function Change

The work function changes of vacuum deposited molybdenum films caused by the chemisorption of propylene, acetylene, hydrogen and nitrogen were measured using the Kelvin vibrating capacitor method. During the hydrocarbon chemisorption, the work function increased in a low surface coverage region but decreased at the higher surface coverages. The saturation values of the work function changes corresponding to complete coverage of the surface by chemisorbed propylene and acetylene equal -0.08 eV and -0.42 eV, respectively. The observed dependences of the work function change on surface coverage are interpreted by the dissociative chemisorption of hydrocarbons on a limited number of surface sites which are simultaneously the sites of preferred adsorption. The extent of dissociation decreases in the adsorption with the increasing surface coverage. The results of the study of the work function changes induced by the hydrogen and nitrogen chemisorption enabled to draw several conclusions on the surface topography of the used films.

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A Comparative Study of Adsorption of Aliphatic Amines at a Gold Electrode

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20052027 ◽

2005 ◽

Vol 70 (12) ◽

pp. 2027-2037 ◽

Cited By ~ 17

Author(s):

Teresa Łuczak

Keyword(s):

Gibbs Energy ◽

Comparative Study ◽

Gold Electrode ◽

Surface Coverage ◽

Standard Gibbs Energy ◽

Gold Surface ◽

Experimental Dependence ◽

Aliphatic Amines ◽

Solvent Interactions ◽

Amine Concentration

Adsorption of aliphatic amines (C1-C4) at the gold electrode was studied by tensammetry. It has been established that the experimental dependence between the gold surface coverage (Θ) and the bulk amine concentration (cA) fits satisfactorily both by the Frumkin and Flory-Huggins isotherms. The standard Gibbs energy of adsorption, ∆G°ad at Emax for Θ < 0.8 has been found to increase in the order methylamine < ethylamine < propylamine < butylamine. This is rationalised in terms of surface-adsorbate, adsorbate-adsorbate and adsorbate-solvent interactions.

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Initial Clinical Experience With a New Conformable Abdominal Aortic Endograft: Aortic Neck Coverage and Curvature Analysis in Challenging Aortic Necks

Journal of Endovascular Therapy ◽

10.1177/1526602821996723 ◽

2021 ◽

pp. 152660282199672

Author(s):

Alice Finotello ◽

Richte Schuurmann ◽

Sara Di Gregorio ◽

Gian Antonio Boschetti ◽

Nabil Chakfé ◽

...

Keyword(s):

Aortic Wall ◽

Surface Coverage ◽

Infrarenal Aorta ◽

Technical Success ◽

Curvature Analysis ◽

Average Curvature ◽

Aortic Neck ◽

Abdominal Aortic ◽

Shortest Distance ◽

New Generation

Objectives: Aim of this work was to investigate precision of deployment and conformability of a new generation GORE EXCLUDER Conformable Endoprosthesis with active control system (CEXC Device, W.L. Gore and Associates, Flagstaff, AZ, USA) by analyzing aortic neck coverage and curvature. Methods: All consecutive elective patients affected by abdominal aortic aneurysm or aortoiliac aneurysm treated at our institution between November 2018 and June 2019 with the new CEXC Device were enrolled. Validated software was adopted to determine the available apposition surface area into the aortic neck, apposition of the endograft to the aortic wall, shortest apposition length (SAL), shortest distance between the endograft fabric and the lowest renal arteries (SFD) and between the endograft fabric and the contralateral renal artery (CFD). Pointwise centerline curvature was also computed. Results: Twelve patients (10 men, median age 78 years (71.75, 81.0)) with available pre- and postoperative computed tomography angiography (CTA) were included. Technical success was obtained in all the cases. Preoperative median length of the proximal aortic neck was 16.1 mm (10.7, 21.7) and suprarenal (α) and infrarenal (β) neck angulation were, respectively, 28.9° (15.7°, 47.5°) and 75.0° (66.9°, 81.4°). Postoperative median apposition surface coverage was 79% (69.25%, 90.75%) of the available apposition surface. SFD and CFD were 1.5 mm (0.75, 5.25) and 7 mm (4.5, 21.5), respectively. Average curvature over the infrarenal aorta decreased from 25 m−1 (21.75, 29.0) to 22.5 m−1 (18.75, 24.5) postoperatively (p=0.02). Maximum curvature did not decrease significantly from 64.5 m−1 (54.25, 92.0) to 62 m−1 (41.75, 71.5) (p=0.1). Conclusions: Our early experience showed that deployment of the CEXC Device is safe and effective for patients with challenging proximal aortic necks. Absence of significant changes between pre- and postoperative proximal aortic neck angulations and curvature confirms the high conformability of this endograft.

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Assessing Surface Coverage of Aminophenyl Bonding Sites on Diazotised Glassy Carbon Electrodes for Optimised Electrochemical Biosensor Performance

Nanomaterials ◽

10.3390/nano11020416 ◽

2021 ◽

Vol 11 (2) ◽

pp. 416

Author(s):

Zari Tehrani ◽

Hina Yaqub Abbasi ◽

Anitha Devadoss ◽

Jonathan Edward Evans ◽

Owen James Guy

Keyword(s):

Carboxylic Acid ◽

Surface Coverage ◽

Electrochemical Biosensor ◽

Electrochemical Techniques ◽

Differential Pulse ◽

Second Step ◽

Glassy Carbon Electrodes ◽

Potential Marker ◽

Pulse Voltammetry ◽

Amine Coupling

Electrochemical biosensors using carbon-based electrodes are being widely developed for the detection of a range of different diseases. Since their sensitivity depends on the surface coverage of bioreceptor moieties, it necessarily depends on the surface coverage of amine precursors. Electrochemical techniques, using ferrocene carboxylic acid as a rapid and cheap assay, were used to assess the surface coverage of amino-phenyl groups attached to the carbon electrode. While the number of electrons transferred in the first step of diazotisation indicated a surface coverage of 8.02 ± 0.2 × l0−10 (mol/cm2), and those transferred in the second step, a reduction of nitrophenyl to amino-phenyl, indicated an amine surface coverage of 4–5 × l0−10 (mol/cm2), the number of electrons transferred during attachment of the amine coupling assay compound, ferrocene carboxylic acid, indicated a much lower available amine coverage of only 2.2 × l0−11 (mol/cm2). Furthermore, the available amine coverage was critically dependent upon the number of cyclic voltammetry cycles used in the reduction, and thus the procedures used in this step influenced the sensitivity of any subsequent sensor. Amine coupling of a carboxyl terminated anti-beta amyloid antibody specific to Aβ(1-42) peptide, a potential marker for Alzheimer’s disease, followed the same pattern of coverage as that observed with ferrocene carboxylic acid, and at optimum amine coverage, the sensitivity of the differential pulse voltammetry sensor was in the range 0–200 ng/mL with the slope of 5.07 µA/ng·mL−1 and R2 = 0.98.

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Influence of surface coverage of kaolin with surfactant ions on adsorption of ochratoxin A and zearalenone

Applied Clay Science ◽

10.1016/j.clay.2021.106040 ◽

2021 ◽

Vol 205 ◽

pp. 106040

Author(s):

Milica Spasojević ◽

Aleksandra Daković ◽

George E. Rottinghaus ◽

Milena Obradović ◽

Danina Krajišnik ◽

...

Keyword(s):

Ochratoxin A ◽

Surface Coverage

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Nanotubular Oxide Layer Formed on Helix Surfaces of Dental Screw Implants

Coatings ◽

10.3390/coatings11020115 ◽

2021 ◽

Vol 11 (2) ◽

pp. 115 ◽

Cited By ~ 1

Author(s):

Magdalena Jażdżewska ◽

Michał Bartmański

Keyword(s):

Oxide Layer ◽

Cross Sections ◽

Surface Coverage ◽

Artificial Saliva ◽

Corrosion Current ◽

Optical Microscope ◽

Significant Difference ◽

Helix Surfaces ◽

Future Work ◽

Oxidation Parameters

Surface modification is used to extend the life of implants. To increase the corrosion resistance and improve the biocompatibility of metal implant materials, oxidation of the Ti-13Nb-13Zr titanium alloy was used. The samples used for the research had the shape of a helix with a metric thread, with their geometry imitating a dental implant. The oxide layer was produced by a standard electrochemical method in an environment of 1M H3PO4 + 0.3% HF for 20 min, at a constant voltage of 30 V. The oxidized samples were analyzed with a scanning electron microscope. Nanotubular oxide layers with internal diameters of 30–80 nm were found. An analysis of the surface topography was performed using an optical microscope, and the Sa parameter was determined for the top of the helix and for the bottom, where a significant difference in value was observed. The presence of the modification layer, visible at the bottom of the helix, was confirmed by analyzing the sample cross-sections using computed tomography. Corrosion tests performed in the artificial saliva solution demonstrated higher corrosion current and less noble corrosion potential due to incomplete surface coverage and pitting. Necessary improved oxidation parameters will be applied in future work.

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