Percent Surface Coverage Research Articles

Reducing the danger of phytopathogen toxins by using an organomineral composition

Relevance. Contamination by toxins of phytopathogens or mycotoxins of food and feed raw materials of plant origin poses a serious threat to the production of high-quality and safe agricultural products. Reducing the risks of contamination of plant raw materials with mycotoxins depends on the effective use of biological products to reduce the toxicity of mycotoxins.Methods. Experiments were carried out on primary rat liver cells. Primary liver cells were cultured in DMEM medium in the presence of 10% fetal calf serum at 37OC and 5% CO2. Zearalenone and T-2 toxin were dissolved in a mixture of DMSO and 96% alcohol in a ratio 1:1. Zearalenone T-2 toxin and protective compositions were mixed and aged together for 6 hours and after exposure added to a medium with a cellular monolayer. The concentration of bacterial-based compositions KMBI-3 and KMCI-3 was used for research in three variants: 0.4 mg/ml, 2 mg/ml, 4 mg/ml. After 24 hours of cultivation, the cell layer was evaluated using an inverted microscope according to the following parameters: percentage of surface coverage, cell shape, number of cell aggregates, number of floating cells.Results. A dose-dependent decrease in cell viability was revealed when exposed to zearalenone and T-2 toxin, the most toxic effect was observed at doses from 0.5 х 10-4 and 8.6 х 10-8 M and 2.14 х 10-7 M, respectively. When using the protective composition KMBI-3 at a dose of 4 mg/ml, the least negative effect of zearalenone and T-2 toxin on cell culture was observed. The use of compositions of organomineral origin KMBI-3 helps to increase cell viability when exposed to the toxins zearalenone and T-2 toxin, which indicates the activation of proliferative processes in comparison with the group without the use of drugs. The use of the biopreparation KMBI-3 reduces the pathogenic effect of zearalenone and T-2 toxin on cell culture, increases the resistance of liver cells to the effects of phytopathogen toxins.

The Multi-Hollow Surface Dielectric Barrier Discharge Usage for the Seeds' Treatment Aimed to the Dustiness Decrease of Free-Floating Particles from Agrochemicals

The Multi-hollow Surface Dielectric Barrier Discharge (MSDBD) generated in ambient air at atmospheric pressure was used to treat maize, pea, wheat and parsley seeds. Plasma exposure was applied as a pre-treatment before the seeds coating with agrochemicals. The aim of this study was to decrease the dustiness of coated seeds using plasma pre-treatment. The optimization process of plasma treatment parameters for individual seed species consisted of choosing a suitable exposure time (20 s, 60 s) and airflow (10 L/min, 15 L/min). The plasma made the seeds' surface more hydrophilic; therefore, better agrochemicals adhesion was achieved on the seeds' surface. Wettability improvement was demonstrated via water uptake of seeds and apparent contact angle change. Ambient air plasma at a 15 L/min flow rate was measured using optical emission spectroscopy, and the values of vibrational (3000 K) and rotational (347 K) temperatures were obtained from spectra simulation. The surface temperature of the MSDBD ceramics plate was measured with a thermal camera for different gas flow rates and constant input power of 30 W because the temperature is crucial parameter for seed treatment. The surface morphology was not affected due to plasma treatment, even for a longer exposure time. A significant decrease in dustiness measured according to the Heubach method was achieved for pea (57.1%) and parsley (41.4%) seeds. A lower decrease in dustiness was registered in the case of wheat (14.6%) and maize (17%) seeds. The results showed that MSDBD plasma generated in the air at optimized conditions is able to decrease the coated seed dustiness regardless of seed type and size, while seeds germination and surface coverage percentage remained unchanged.

Photoluminescence of tin dioxide (SnO2) nanostructure grown on Si(001) by thermal evaporation technique

This work reports the growth and photoluminescence of tin dioxide (SnO2) nanostructure on Si (001) substrate. The growth was done by thermal evaporation of tin and subsequent air exposure at room temperature. The in situ low energy electron microscopy and atomic force microscopy studies indicated that the growth followed the Volmer-Werber growth mode leading to the formation of SnO2 island nanostructure with the smallest island size of 86 ± 10 nm and the highest percentage of surface coverage of 53% at the substrate temperature of 225 °C. The grazing incident X-ray diffraction and X-ray photoelectron spectroscopy results confirmed the formation of amorphous SnO2 nanostructure. The photoluminescence spectra under the excitation of 350 nm radiation at room temperature showed two emission peaks in the yellow region at 574.0 nm and 555.9 nm, and three emission peaks in the blue region at 450 nm, 467 nm, and 478 nm. The CIE (x,y) chromaticity calculated from the emission spectra showed that the coordinators were located at approximately x = 0.2419 and y = 0.3089 in a region of white emission.

Synthesis of Gemini cationic surfactants based on natural nicotinic acid and evaluation of their inhibition performance at C-steel/1 M HCl interface: Electrochemical and computational investigations

Herein, we prepare effective Gemini cationic surfactants (CSII, CSIV) and characterize them using FT-IR and 1HNMR spectroscopy. The adsorptive properties of CSII and CSIV at HCl/air and C-steel/HCl interfaces were examined with surface tension and electrochemical parameters, respectively. The critical micelle concentration (CMC) of the CSII and CSIV indicated their adsorption affinity at the HCl/air interface. Where, aliphatic chains increase surface coverage percentage and aid in surfactant adsorption. The electrochemical parameters of C-steel in 1 M HCl were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) at different temperatures. The charge transfer resistance of the C-steel electrode was enhanced from 28.2 Ω.cm2 to 770.79 and 831.45 Ω.cm2 after adding 5 × 10−4 M of CSII and CSIV, respectively. Both CSII and CSIV act as mixed inhibitors with inhibition performance exceeding 97% due to their highly adsorption affinity. The chemical adsorption affinity of these compounds is suggested by the higher adsorption energy (∆G*ads) values (>−40 kJ mol−1) according to the Langmuir isotherm model. The theoretical calculations including DFT, and Monte Carlo simulation (MCs) provide insight into the relationship between corrosion inhibition and molecular structure, where the calculated parameters agree with the experimental results.

The impact of biofilm on marine current turbine performance

Although several problems related to biofouling of marine current turbines (MCTs) are reported in the literature, the most important one is related to long-term operational performance and maintenance costs. Nevertheless, studies related to the impact of biofouling on MCT performance are rather scarce. In this study, the impact of biofilm on MCT performance is investigated using the Computational Fluid Dynamics (CFD) approach. Biofilm is modelled using previously developed roughness functions implemented in a wall function solver. A verification study is performed to determine sufficient grid spacings and to calculate numerical uncertainty. The validation study is conducted by comparing the obtained results with experimental and numerical ones from the literature. Full-scale CFD simulations are performed for six fouling conditions with varying biofilm height and percentage of surface coverage at eight tip speed ratios (TSRs). The obtained results highlight the significant impact of biofilm on MCT performance reflected in a decrease in the power coefficient, which for the optimal TSR is equal to −10.7% for the R1 fouling condition. Finally, a detailed analysis of the flow around MCTs fouled with biofilm is conducted and the reasons for the detrimental impact of biofilm on MCT performance are discussed.

Gold-seeded Lithium Niobate Nanoparticles: Influence of Gold Surface Coverage on Second Harmonic Properties.

Hybrid nanoparticles composed of an efficient nonlinear optical core and a gold shell can enhance and tune the nonlinear optical emission thanks to the plasmonic effect. However the influence of an incomplete gold shell, i.e., isolated gold nano-islands, is still not well studied. Here LiNbO3 (LN) core nanoparticles of 45 nm were coated with various densities of gold nano-seeds (AuSeeds). As both LN and AuSeeds bear negative surface charge, a positively-charged polymer was first coated onto LN. The number of polymer chains per LN was evaluated at 1210 by XPS and confirmed by fluorescence titration. Then, the surface coverage percentage of AuSeeds onto LN was estimated to a maximum of 30% using ICP-AES. The addition of AuSeeds was also accompanied with surface charge reversal, the negative charge increasing with the higher amount of AuSeeds. Finally, the first hyperpolarizability decreased with the increase of AuSeeds density while depolarization values for Au-seeded LN were close to the one of bare LN, showing a predominance of the second harmonic volumic contribution.

Pyrrolidine-based quaternary ammonium salts containing propargyl and hydrophobic C-12 and C-16 alkyl chains as corrosion inhibitors in aqueous acidic media

A new series of industrially relevant pyrrolidine based quaternary ammonium salts containing propargyl motif and hydrophobic C-12, C-16 alkyl chains were synthesized in excellent yields and evaluated for mild steel corrosion in 1 M HCl. FT-IR, NMR, and TGA were analyzed to characterize these corrosion inhibitors. The performance of these corrosion inhibitors was examined by gravimetric weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and theoretical calculations using density functional theory (DFT) methods. The surface morphology of mild steel samples was studied by UV–vis spectroscopy, scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). Results revealed that the inhibition capabilities of corrosion inhibitors N, N-dipropargylpyrrolidium bromide (DPPB), N-dodecyl, N-propargylpyrrolidium bromide (DDPPB), N-hexadecyl, N-propargylpyrrolidium bromide (HDPPB) are concentrations, immersion time and temperature-dependent, and found to be very good inhibitors even at a meager concentration of 60.3 μmol L−1 with an efficiency value 92.6, 93.7, and 96.2%, respectively. The inhibition efficiency order of these corrosion inhibitors, as shown by gravimetric and electrochemical studies, is as follows: HDPPB > DDPPB > DPPB. The inhibition efficiencies obtained from gravimetric weight loss, PDP, and EIS measurements are in good agreement. The thermodynamic parameters such as Ea, Kads, ΔG°mic, and ΔG°ads were determined. As compare to ΔG°mic, the more negative ΔG°ads values suggested favorable adsorption over the micellization. The critical micelle concentration (CMC) values of DPPB, DDPPB, and HDPPB were found to be 35.5, 31.8, and 30.0 mmol L−1. At CMC, the percent surface coverage was ≈90%, revealed that the monolayer formation by the inhibitor molecules at the metal/solution interface is almost complete before the concentrations reach their CMC values. Electrochemical studies suggested that corrosion inhibitors DPPB and DDPPB act as a mixed type with predominantly cathodic inhibitors, while HDPPB serves as a cathodic inhibitor. Surface analysis by UV–vis spectroscopy, SEM, and XPS supported the adsorption of inhibitor molecules on the mild steel surface. The DFT analysis is in good agreement with the experimentally obtained results on the molecular structure and adsorption strength.

Optical dielectric function of two-dimensional WS2 on epitaxial graphene

Heterostacks composed of two-dimensional WS2 and graphene exhibit interesting opto-electronic properties, including ultrafast charge transfer and fast, efficient photodetection. The optical properties of WS2 are heavily influenced by the presence of graphene in the heterostack, yet, so far, their characterization in the whole visible range is missing. In this work we report the complex dielectric function of two-dimensional WS2 flakes on epitaxial graphene on silicon carbide, obtained by means of spectroscopic ellipsometry (SE). The so-called A, B and C excitonic features are precisely identified, and significant differences with respect to literature data of WS2 on fused silica are highlighted. Since this investigation is based on SE, the complex dielectric function of WS2 is retrieved without performing Kramers Kronig analysis, which is instead necessary when employing reflectance or transmittance spectroscopy. Furthermore, the approach described in this work can be used in principle to characterize any two-dimensional flakes, both in terms of complex dielectric function and percentage of surface coverage.

A study on the interaction between chloride ions and CO2 towards carbon steel corrosion

This article addresses the knowledge gap in the area of the interaction between Cl− and CO2 on carbon steel pipelines by comprehensively evaluating the corrosion behaviour of AISI 1020 carbon steel exposed to solutions containing Cl− and/or CO2 over time periods between 0.5 and 72 h at 60 °C. The results show Cl− can reduce the surface coverage percentage of corrosion products and contributes greatly to film breakdown. The carbon steel is thus exposed to the corrosive solution containing CO2 species, accelerating the further propagation of corrosion pits.

Is hand surface coverage a good measure of hand hygiene effectiveness?

Background: Effective hand hygiene (HH) is fundamental to the prevention of healthcare-associated infections. One of the commonly used ways for assessing the effectiveness of HH procedure is measuring the extent of hand surface coverage with alcohol-based handrub (ABHR). Methods: In this Latin square design study, handrubbing with ABHR was performed seven times by each of the 35 volunteers. Volunteers’ hands were contaminated with the Escherichia coli K12 strain as per EN 1500 guidelines. Glove juice samples were collected from their hands before and after each ABHR application and surface coverage was measured using Hand-in-Scan® scanner. The relationship between the bacterial log10 reduction and percent surface coverage was analysed using Spearman’s Rank Order Correlation and simple linear regression. Results: Surface coverage ranged from 49.38% to 100% (N= 208, Mdn: 97,33%, IQR= 83.52 – 99.93), while the E. coli reduction ranged from 0.96 to 5.92 log10 (N= 221, M: 3.07, SD= 0.94). The Spearman’s Rank Order Correlation results showed no significant correlation between percent hand surface coverage and E. coli log10 reduction [r= -0.009, n= 198, p= 0.905]. The lack of correlation was further confirmed by the linear regression. Conclusions: These findings suggest that the rate of surface coverage does not correlate with reduction in bacterial load on hands following HH. Although visual feedback on surface coverage can be a good approach to teaching the correct HH technique, these findings suggest that surface coverage alone is not a reliable measure of HH effectiveness.

Prevalence, Molecular Typing, and Determination of the Biofilm-Forming Ability of Listeria monocytogenes Serotypes from Poultry Meat and Poultry Preparations in Spain.

A study was undertaken of the presence of Listeria monocytogenes in 260 samples of poultry meat obtained from retail outlets in northwestern Spain. L. monocytogenes was detected in 20 samples (7.7%). Twenty strains (one strain per positive sample) were characterized. The strains belonged to 10 serotypes: 1/2a (2 strains), 1/2b (2), 1/2c (2), 3a (1), 3b (2), 3c (2), 4a (2), 4b (4), 4c (1), and 4d (2). Cluster analysis (ribotyping; EcoRI) showed a strong genetic relationship between strains isolated from samples coming from different outlets. Ribotyping permitted some isolates of the same serotype to be differentiated, which points to the possible usefulness of this technique in the epidemiological surveillance of L. monocytogenes. All strains formed biofilm on polystyrene, as shown by confocal laser scanning microscopy. The biovolume (between 621.7 ± 36.0 µm3 and 62,984.0 ± 14,888.2 µm3 in the observational field of 14,161 μm2), percentage of surface coverage (from 2.17 ± 0.84% to 94.43 ± 3.97%), roughness (between 0.399 ± 0.052 and 0.830 ± 0.022), and maximum thickness (between 9.00 ± 0.00 µm and 24.00 ± 14.93 µm) of biofilms varied between strains (p < 0.05). These results expand knowledge of the characteristics of L. monocytogenes isolates from poultry.

Vegetation recovery after the removal of a facility in Elephant Island, Maritime Antarctic

AbstractThis study aimed to evaluate the speed of revegetation of Antarctic soil affected by 13 years of anthropogenic influence in the form of a refuge building at Stinker Point, Elephant Island, Antarctica. Fourteen years after the removal, in the 2011/2012 austral summer, a qualitative survey of the vegetation cover and biodiversity was conducted using photographs and image processing of the entire field. Data were compared with records from the Technical Archive of the Brazilian Antarctic Program. Recovery had occurred at a faster rate than expected. There was a rapid covering of Deschampsia antarctica Desv. (Poaceae), Sanionia uncinata (Hedw.) Loeske, and Bryum argentum Hedw. (Bryophyta), evidenced by the larger percentage of surface coverage and frequency by these species. The findings are important because they help establish new concepts on environmental security related to preserving plant communities in new Antarctic settlements or camps, supporting that the rapid recovery of the ecosystem after their removal is possible.

Tuning the stability and microstructure of fine Pickering emulsions stabilized by cellulose nanocrystals

Cellulose nanocrystals (CNCs) as Pickering emulsion stabilizers have attracted fast increasing interests in the food, pharmaceutical and cosmetic fields, due to their sustainability and biocompatibility. However, it still remains a debate for unmodified CNCs to act as a kind of effective Pickering stabilizers, due to their high hydrophilic nature. This work for the first time reported that CNCs were compatible with using microfluidization as the emulsification process to produce a kind of fine Pickering emulsions, with surface-average droplet sizes as low as 0.22 μm. As compared with other emulsification processes, the Pickering emulsions by the microfluidization were more stable against coalescence but readily prone to droplet flocculation and creaming. The droplet flocculation in these emulsions was mainly associated with the formation of bridging droplets with two different droplets sharing a same monolayer. The droplet size, microstructure and stability (against creaming and coalescence) of these emulsions by the microfluidization could be well tuned by varying the particle concentration (c; 0.3–1.2 wt%) and/or oil fraction (ø; 0.1-0.4). In general, the finer Pickering emulsions with more serious bridging flocculation were formed at lower ø and/or higher c values, while the emulsions at lower ø and c values were more prone to creaming. The Pickering emulsions with smaller droplet sizes exhibited a much better coalescence stability. Interestingly, the amount of adsorbed CNCs at the interface was relatively high, and the percentage of surface coverage at interface was low (ranging from 11.3 to 50.0%). The results confirmed that using the microfluidization as the emulsification technique, CNCs exhibit a good ability to stabilize the Pickering emulsions, with the microstructure and stability well-modulated by varying the c and/or ø. The findings would be of great relevance for the development of nanoscale CNC Pickering emulsions suitable for food and pharmaceutical formulations.

Tunable mechanical properties of graphene by clustered line pattern hydroxyl functionalization via molecular dynamics simulations

The effects of clustered line patterns of hydroxyl functionalization and percent surface coverage along the armchair and zigzag directions of the graphene lattice on the mechanical response of graphene sheets (GS) under tension loading, in zigzag and armchair directions, and under shear loading in the zigzag direction were studied. The initial, functionalization induced bending deformation, caused by clustered line pattern arrangements, led to strong elastic anisotropy of graphene with an increased linear compressibility in the direction perpendicular to the line patterns and increased stiffness in the direction parallel to the line patterns. The line pattern functionalized graphene acted similar to a nanoscale mechanical spring. It is shown that clustered line pattern functionalization along the zigzag direction can increase the stiffness of the GS along the zigzag direction and stretchability along the armchair direction without significantly stretching the carbon bonds and can enhance the toughness of the GS relative to random functionalization. It was also found that the Poisson's ratio can be tuned from positive to negative through line pattern arrangements, reaching a minimum of −0.287 at an –OH percentage of 75% for stretching along the zigzag direction, thus indicating auxetic behavior.

A New Flow-Based Assay to Assess Treatment Response in Congenital Thrombotic Thrombocytopenic Purpura

IntroductionCongenital TTP (cTTP) is an ultra-rare disorder in which deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) results in circulating ultra large Von Willebrand Factor (VWF) multimers and subsequent microthrombi formation. Regular prophylactic therapy aims to improve outcomes from long-term complications, but also ongoing symptoms, including lethargy, headaches and abdominal pain, despite normal blood counts. Existing methods of quantifying ADAMTS13 activity lack the sensitivity to enable their use for evaluating treatment response in patients with cTTP. We present a novel flow-based assay with the aim of assessing treatment response, novel therapeutic options and analyzing the impact of different mutations on disease severity.MethodA VenaFlux semi-automated microfluidic system was used to provide shear flow to mimic in vivo flow rates. Using whole blood, we analyzed platelet adhesion, aggregation and thrombi formation on microchannels coated with type I collagen and mounted onto the stage of an inverted epifluorescence microscope. Fresh, citrated whole blood was treated with DiOC6 to achieve platelet fluorescence and a macro on Image-Pro Premier was designed for automated calculation of total surface coverage. Surface coverage represented increasing thrombus formation with total coverage by thrombus within 180 seconds quantified as 100% coverage.Results were compared to a normal range developed using 43 normal controls (26=female, 17=male) with normal hemoglobin, platelet count and hematocrit. The surface coverage normal range was 6-39%.cTTP samples were analyzed for complete blood count, ADAMTS13 activity, VWF antigen, VWF activity and percentage surface coverage. Samples were taken 30 minutes before and after prophylactic treatment, either plasma infusion or BPL-8Y. Recombinant ADAMTS13 was added in-vitro on all pre-treatment samples with 15 minutes incubation time. Further re-measurement was undertaken after initiation of aspirin for at least ten days.ResultsEighteen patients with cTTP confirmed by genetic analysis and ADAMTS13 levels <5 IU/dl were included (16 = female, 2 = male) with a median age of 33 (range: 15-69 years). Median VWF antigen levels: 114% (range: 54% - 276%, NR: 50-160%) and median VWF activity levels: 173% (range: 83% - 338%, NR: 50-187%).The median pre-treatment surface coverage was 90% (range 47% - 100%). There was no significant difference in surface coverage considering genetic mutation type (median coverage for homozygous patients 88%, heterozygous 67%, p=0.99), mutation location (pre-spacer mutation surface coverage 67%, post spacer mutation surface coverage 84%, p=0.84), or age of first symptom onset (childhood onset surface coverage 59%, adult onset 86%, p=0.19).Plasma infusion improved surface coverage results with pre treatment coverage of 90% compared to 44% post plasma infusion (p=0.0003). In vivo recombinant ADAMTS13 administration on pre prophylaxis samples, resulted in normalization of surface coverage in all patients (p<0.0001)(median post rADAMTS13 coverage 28%, range 3-39%). In patients initiated on aspirin, surface coverage had improved both pre and post prophylaxis. The median pre treatment surface coverage for patients on aspirin was 51% (vs. 90% pre treatment and no aspirin, p=0.004). This improvement persisted after treatment with post treatment surface coverage of 18% (vs. 44% post treatment but not on aspirin, p=0.003). 100% of patients who received aspirin saw surface coverage return to the normal range post treatment compared to 82% with plasma infusion alone (p=0.0195).ConclusionPlasma infusion and aspirin synergistically reduce surface coverage by thrombus in patients with cTTP, demonstrated on peak and trough samples. Furthermore, in vitro addition of recombinant ADAMTS13 completely normalized thrombus formation. There were no major differences in surface coverage by genetic mutation. The newly developed flow-based assay presented can be used to assess treatment options and efficacy in cTTP in addition to demonstrating cTTP disease pathophysiology that has not previously been identified. In combination with clinical symptoms it offers potential to improve and personalize treatment for patients with cTTP. [Display omitted] DisclosuresLiesner:Bayer: Consultancy, Research Funding; Sobi: Speakers Bureau; Roche: Research Funding; Baxalta: Consultancy, Research Funding; Novo Nordisk: Research Funding, Speakers Bureau; Octapharma: Consultancy, Other: Clinical study investigator for NuProtect Study (Octapharma sponsored), Research Funding, Speakers Bureau. Scully:Novartis: Honoraria, Other: Member of Advisory Board, Speakers Bureau.

Polystyrene nanoparticles as a flotation collector: A molecular dynamics study

Nanoparticles have significant potential as new candidates for generating new types of flotation reagents with unique performance for wettability design and control. Hence, this study explores the wettability of a glass surface covered with polystyrene nanoparticles at various surface coverage percentage using molecular dynamics simulations. To investigate wettability on the bare and coated glass surface, the dynamics of water molecules, contact angle, density distribution profile, and hydrogen bonding patterns are analyzed as substrate wettability indicators. The results reveal that both unrelaxed and relaxed forms of glass surface tolerate a strong asymmetric distribution of surface energy in general, due to charge accumulation on the surface leading the surface to strong hydrophilic behavior. However, unlike chemical collectors, partial covering of glass surface with cationic polystyrene nanoparticles up to 10% reduces the surface tension to a favorable level of hydrophobicity for flotation.

Investigation spatial distribution of droplets and the percentage of surface coverage during dropwise condensation

The aim of this research is to develop an algorithm to simulate droplets nucleation and growth during dropwise condensation in order to study the droplets spatial distribution. The proposed algorithm starts with droplets distributed based on the Poisson point process and investigates the spatial distribution of droplets using Ripley's L function method. Also, the effects of substrate temperature (Tw) and initial density (ND) on the percentage of area occupied by droplets (ϕ) are studied. Good agreement between model predictions and experimental data for the rate of growth and changes in droplets density (Nt) as well as spatial distribution of droplets verifies the validity of the simulating model.

Irreversible Adsorption of Asphaltenes on Kaolinite: Influence of Dehydroxylation

The adsorption of asphaltenes on dehydroxylated mineral surfaces is an important occurrence during thermal processing of unconventional oil resources such as oil sands bitumen. We investigated the irreversible adsorption of Athabasca asphaltenes from toluene solutions onto untreated and dehydroxylated kaolinite. The adsorption density, percent surface coverage, and mean domain thickness were evaluated using X-ray photoelectron spectroscopy (XPS) and elemental analysis. The dehydroxylated kaolinite gave higher adsorption density and percent surface coverage than the untreated kaolinite, as particularly revealed in multiple contacts of kaolinite with the asphaltene-in-toluene solutions (2 g/L), indicating that dehydroxylation of kaolinite enhanced its adsorption capacity for asphaltenes. The XPS-determined percent surface coverage was 18% and 41% on the untreated and dehydroxylated kaolinite, respectively, corresponding to the maximum adsorption density of 3 and 7 mg/m2. The incomplete coverage even at the ...

Layer-Number Dependent Antibacterial and Osteogenic Behaviors of Graphene Oxide Electrophoretic Deposited on Titanium

Graphene oxide has attracted widespread attention in the biomedical fields due to its excellent biocompatibility. Herein we investigated the layer-number dependent antibacterial and osteogenic behaviors of graphene oxide in biointerfaces. Graphene oxide with different layer numbers was deposited on the titanium surfaces by cathodal electrophoretic deposition with varied deposition voltages. The initial cell adhesion and spreading, cell proliferation, and osteogenic differentiation were observed from all the samples using rat bone mesenchymal stem cells. Both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were used to investigate the antibacterial effect of the modified titanium surfaces. Cocultures of human gingival fibroblasts (HGF) cells with Escherichia coli and Staphylococcus aureus were conducted to simulate the conditions of the clinical practice. The results show that the titanium surfaces with graphene oxide exhibited excellent antibacterial and osteogenic effects. Increasing the layer-number of graphene oxide resulted in the augment of reactive oxygen species levels and the wrinkling, which led to the antibacterial and osteogenic effects, respectively. Compared to pure titanium surface in the cells-bacteria coculture process, the modified titanium surfaces with graphene oxide exhibited higher surface coverage percentage of cells.

Surface coverage with single vs. multiple gaze surface topography to fit scleral lenses.

To determine surface coverage of measurements using the sMap3D® corneo-scleral topographer in patients presenting for scleral lens fitting. Twenty-five eyes of 23 scleral lens patients were examined. Up-gaze, straight-gaze, and down-gaze positions of each eye were "stitched" into a single map. The percentage surface coverage between 10mm and 20mm diameter circles from corneal center was compared between the straight-gaze and stitched images. Scleral toricity magnitude was calculated at 100% coverage and at the same diameter after 50% of the data was removed. At a 10mm diameter from corneal center, the straight-gaze and stitched images both had 100% coverage. At the 14, 15, 16, 18 and 20mm diameters, the straight-gaze image only covered 68%, 53%, 39%, 18%, and 6% of the ocular surface diameters while the stitched image covered 98%, 96%, 93%, 75%, and 32% respectively. In the case showing the most scleral coverage at 16mm (straight-gaze), there was only 75% coverage (straight-gaze) compared to 100% (stitched image); the case with the least coverage had 7% (straight gaze) and 92% (stitched image). The 95% limits of agreement between the 50% and 100% coverage scleral toricity was between -1.4D (50% coverage value larger) and 1.2D (100% coverage larger), a 2.6D spread. The absolute difference between 50% to 100% coverage scleral toricity was ≥0.50D in 28% and ≥1.0D in 16% of cases. It appears that a single straight-gaze image would introduce significant measurement inaccuracy in fitting scleral lenses using the sMap3D while a 3-gaze stitched image would not.