Surface Coverage Rate Research Articles

Effect of tilt angle and drying temperature on the surface coverage rate of polystyrene nanospheres in evaporation-driven self-assembly process

Effect of tilt angle and drying temperature on the surface coverage rate of polystyrene nanospheres in evaporation-driven self-assembly process

Shear Histories Alter Local Shear Effects on Thrombus Nucleation and Growth.

Our goal was to determine the impact of physiological and pathological shear histories on platelet nucleation and thrombus growth at various local shear rates. We designed and characterized a microfluidic device capable of subjecting platelets to shear histories reaching as high as 6700s in a single passage. Time-lapse videos of platelets and thrombi are captured using fluorescence microscopy. Thrombi are tracked, and the degree of thrombosis is evaluated through surface coverage, platelet nucleation maps, and ensemble-averaged aggregate areas and intensities. Surface coverage rates were the lowest when platelets deposited at high shear rates following a pathological shear history and were highest at low shear rates following a pathological shear history. Early aggregate area growth rates were significantly larger for thrombi developing at high shear following physiological shear history than at high shear following a pathological shear history. Aggregate vertical growth was restricted when depositing at low shear following a pathological shear history. In contrast, thrombi grew faster vertically following physiological shear histories. These results show that physiological shear histories pose thrombotic risks via volumetric growth, and pathological shear histories drastically promote nucleation. These findings may inform region-based geometries for biomedical devices and refine thrombosis simulations.

Examining the effectiveness of Guava leaf extract in mitigating corrosion of aluminium in potassium hydroxide solution

This study is on the effectiveness of guava leaf extract in mitigating corrosion of aluminium in potassium hydroxide solution. Functional groups of the extract were revealed using Fourier transform infrared spectroscopy. In addition, qualitative and quantitative analyses of the extract were carried out to ascertain the level of the phytochemicals. Effects of process variables on the effectiveness of guava leaf extract as corrosion inhibitor were determined. Then, modeling of the experimental data of inhibition efficiency of the guava leaf extract was carried using response surface methodology. In the process, modeling of the inhibition efficiency was actualized using design expert software version 11. Analysis of variance and diagnostic analysis of the model on interactive effects of inhibitor concentration, temperature and time on the inhibition efficiency were examined. Analysis of the results showed that the main functional groups of guava leaf are O-H stretch, C-H stretch, N-H bend, CH3C-H bend, C-O stretch and C-H bend. Alkaloid was found to be highly concentrated in the extract; 223.71 ±0.12 mg/100g. Tannins, flavonoids, phytates and saponins were present at moderate (concentrated) levels. Weight loss, corrosion rate, inhibition efficiency and degree of surface coverage were influenced by the inhibitor concentration, temperature and time. Quadratic model adequately described the relationship between inhibition efficiency and process variables. The predicted R² of 0.9311 is in reasonable agreement with the adjusted R² of 0.9867. Guava exhibited high inhibition efficiency. Hence, it can be used to inhibit corrosion of Al in KOH solution.

The optimization of self-assembled monolayer of thiols on screen-printed gold electrode

<span>The activated gold-modified electrode surface for self-assembled monolayer (SAM) is suitable for N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC), 16-mercaptohexadecanoic acid (16-MDA), and N-hydroxysuccinimide (NHS). The various substrates could potentially be used for surface functionalization that binds to one another. Using modified screen-printed gold electrodes, 16-MDA, EDC, and NHS, we developed a self-assembling monolayer. Different 16-MDA concentrations were applied to the surface of a screen-printed electrode surface to enhance the sensitivity of the working electrode. The impact of different EDC, NHS, and 16-MDA concentrations (0.4 M, 0.8 M, 1 M, 1.2 M, 1.4 M, and 1.8 M) and incubation times between 5 and 30 minutes were examined and compared. The binding surface of the screen-printed gold electrode was characterized using the differential pulse voltammetry (DPV) technique. It has been demonstrated that the substrate concentrations at 5 minutes and 30 minutes of incubation time used to have the highest surface coverage and electron transfer rates. This concentration would be utilized in the subsequent experiment to evaluate the binding of various bacterial species. These findings suggest that the SAM in a modified screen-printed gold electrode may be functionalized to detect microorganisms.</span>

Inhibitory Effect of Heparin/Polyarginine/Hyaluronic Acid Complex on Coronary Artery Restenosis by Loading Vascular Endothelial Growth Factor

This research was aimed to investigate the inhibitory effect of heparin/polyarginine/hyaluronic acid (HPHA) complex loaded with vascular endothelial growth factor (VEGF) on coronary artery restenosis (CAR). Dopamine was grafted to obtain dopamine-hyaluronic acid (DPA) composite material, and heparin/polyarginine (HP) nanoparticles (NPs) loaded with VEGF were obtained through electrostatic binding (ESB). The HP NPs loaded with VEGF mixed with hyaluronic acid (HA) were mixed in a 10:1 volume ratio to obtain a composite solution, namely HPHA complex. Next, the sodium metaperiodate was added to form a hydrogel. The samples were characterized using a zeta potential (ZP) analyzer, transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR), and water contact angle (WCA). Enzyme-linked immunosorbent assay (ELISA) and toluidine blue O (TBO) staining were employed to assess the immobilization and release of VEGF and heparin. Rhodamine staining was adopted to evaluate the adhesion of platelets, fibrinogen, macrophages, and umbilical artery smooth muscle cells (UASMCs). Furthermore, CCK-8 assay was performed to evaluate the adhesion and proliferation of endothelial cells (ECs). The results revealed that compared to 0 mg/L, the particle size (PS), polydispersity index (PDI), and θ angle decreased, and the absolute value of ZP increased at 100, 200, 300, and 400 mg/L. The cumulative release (CR) of VEGF at 200 mg/L was higher to that at 0 mg/L, while that of heparin was lower (P <0.05). The platelet surface coverage rate (PSCR), relative platelet activation rate (RPAR), and fibrinogen coverage rate (FCR) at 10 and 20 days were lower and exhibited great difference to those at 0 mg/L (P <0.05). Compared to groups II and III, group I presented a markedly higher number of macrophages and UASMCs on the first and third days of culture (P <0.05). 3 days after culture, adhesion and proliferation of ECs in groups U, I, and K increased greatly (P <0.05). In conclusion, the HPHA complex prepared from HP NPs loaded with VEGF and HA in this research exhibited good stability, uniformity, hydrophilicity, and blood compatibility. It effectively blocked the adhesion of macrophages and UASMCs and promoted the proliferation of ECs, thus conforming to the mechanism of inhibiting CAR after coronary stent intervention.

Altered landscape pattern dominates the declined urban evapotranspiration trend

Urbanization has significantly altered the regional hydrological cycle and thermal environment. However, the response of urban evapotranspiration (ETu) to these altered urban landscape patterns remains unclear. This study proposes a hybrid ETu model that combines physics processes and machine learning to evaluate trends and drivers of ETu across 480 cities in China. The results indicate that the long-term average ETu across the 480 cities is 508 mm, and the average rate of decline in ETu (DRETu) across the 480 cities is 2.19 mm/year. DRETu exhibits a positive correlation with the increasing rate of urban aridity index (AI) and fractional impermeable surface coverage (fi). The decrease in ETu is primarily caused by the altered urban landscape patterns, which include: 1) reductions in urban vegetation and water body areas resulting from urbanization; and 2) the substitution of natural forest land with landscape grasslands in urban areas. We further investigated the correlation between the urban heat island (UHI) effect and ETu and found that the intensified UHI effect is caused by an increased difference in ETu between the main urban area and the suburbs. The results of this study emphasize the significance of constructing water bodies and green infrastructure in the central urban area, as well as restoring natural forests, to enhance the thermal comfort of the urban environment.

Influence mechanism of a compound collector from coal tar and dodecane in the flotation of fine molybdenite particles

With the depletion of high-grade molybdenum (Mo) deposits, it is more pressing to separate the low-grade deposits effectively due to the large demand for Mo. However, traditional hydrocarbon oil collectors such as kerosene suffered low collecting capacity for low-grade ores because of the fine disseminated nature and crystal anisotropy of molybdenite. In this study, the effect of a compound collector prepared from coal tar and dodecane (CTD) on the flotation of fine molybdenite was investigated by micro-flotation experiments, bubble-particle attachment tests, gas chromatography-mass spectrometry (GC–MS), density functional theory (DFT) calculations, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The results of micro-flotation experiments demonstrated that CTD improved the flotation recovery of fine molybdenite dramatically compared with dodecane and kerosene, the fine particles pretreated with CTD had a better affinity for bubbles, and a stronger mineralization efficiency was achieved than that with dodecane as the improvement of the surface coverage and attachment rate constant. The results of GC–MS, FTIR, and DFT calculations indicated that there were plenty of compounds with benzene rings in the CTD, especially for phenanthrene and naphthalene, which showed a stronger interaction on the (100) plane of molybdenite than dodecane, thereby proving a stronger affinity for hydrophilic planes. The results of XPS analysis depicted that more adsorption amounts were achieved on molybdenite by CTD than that of dodecane, and contact angle test results further demonstrated that the effect of CTD was stronger than dodecane in improving the hydrophobicity of fine molybdenite particles. In general, the compound collector (CTD) is beneficial to the improvement of attachment rate of molybdenite particles to bubble and hydrophobicity of molybdenite particles, which improves the flotation recovery of fine molybdenite. The extract from coal tar had more affinity for the (100) plane of molybdenite compared to the (001) plane through DFT calculations. The finding has important reference value and guiding significance for the future research on collectors for fine molybdenite flotation.

Automated Exposures Selection for High Dynamic Range Structured-Light 3-D Scanning

Structured light (SL) scanning has gained widespread applications in industrial metrology; however, measuring objects that have large surface-reflectivity variations is challenging. For this purpose, the high dynamic range (HDR) technique has become a standard method to fuse features under multiple exposures. Presently, in HDR measurement, manual or cumbersome exposure selection strategies are used. This paper reports a new exposure selection approach. An image quality metric is designed to evaluate captured images and suppress regional overexposure, based on which a multiple-exposures selection strategy is developed. Unlike existing methods for single-optimal exposure selection, in our approach, pixel-filtering is introduced to locate eligible pixels and candidate pixels in next exposures. Experimental results with industrial parts having large surface-reflectivity variations demonstrated that compared to HDR with 15 exposures (equal time intervals), our proposed approach achieved a similar surface coverage rates (97.4% vs. 98.1%) and measurement accuracy (0.043 mm vs. 0.041 mm), but only took 3-4 exposures averagely.

Condensation distribution and evolution characteristics of water vapor in annulus of flexible riser

Water vapor penetrating an annulus causes condensation and corrosion and endangers the safe operation of the flexible riser. However, in current studies, the condensation of water vapor in the annulus is modeled based on the film condensation hypothesis, which assumes that the metal material is uniformly corroded. This assumption differs from the true corrosion incidents, which are usually initiated by localized corrosion. To further study the condensation law of water vapor in a flexible riser annulus, the evolution of water vapor condensation on the wall surface of a sapphire reactor was evaluated using an annular condensation experimental device. A water vapor condensation growth model was established to analyze the condensation law and its influencing factors. The results show that the maximum radius of condensate droplets on the annular wall surface is approximately 0.48 cm, the average radius of droplets is approximately 0.35 cm, and the volume of condensate that can be accommodated in the 18 × 18 mm simulation area is approximately 0.5 cm3. After the droplet reaches the departure radius and falls off a surface, the time of recondensation is faster than that of the first condensation. The condensation surface coverage increases rapidly in the early stage and then gradually slows down. After stabilization, the maximum coverage can reach 80%. Parameter analysis suggests that the number of fixed nucleation points on the condensation wall affects the time to reach the departure radius and the increasing rate of surface coverage. However, the number of fixed nucleation points has minimal influence on the departure radius and coverage outcomes. The findings of this study establish a theoretical foundation for predicting dropwise condensation behaviors in annulus of pipelines and developing corrosion protection strategies that modify the wall contact angle or structure.

Ascorbyl Palmitate-Vitamin C Effective Friction Modifier and Wear Inhibitor for Steel in a PAO Base Oil

Ascorbyl palmitate (AP), known as a nutrition pill, and an antioxidant agent in food, has demonstrated excellent lubricity as an additive in PAO4. Adding one wt% AP in PAO4 drastically decreases friction Coefficient (CoF) up to 66% and protects the steel surface from wear. Meanwhile, it shows a more vital friction reduction ability than conventional Mo-based additives and fatty acids, especially palmitic acid. Ascorbic acid core on AP optimises palmitic acid lubricity by forming robust chemical C-O-Fe bond on steel, increasing surface coverage rate. Masked by AP self-assembled layers, steel surfaces can also handle extreme pressure (up to 2.34 GPa) and temperature (150 °C) with unmeasurable wear. This work broadens human-friendly AP vitamin C application for industrial use and introduces a new pathway for optimizing fatty acids lubricity.

Erosion and covered zones altered by surface coverage effects on soil nitrogen and carbon loss from an agricultural slope under laboratory-simulated rainfall events

Soil erosion, one of the most serious environmental concerns, might remove topsoil and essential element from terrestrial land. However, few attentions have been given to investigating how soil erosion regimes affect soil carbon and nitrogen loss. Therefore, this study investigated the effects of surface coverage rates (83%, 67%, 50%, 33%, 17% and 0%) and two positions (up- and downslope) on erosion regimes and its associated soil nitrogen and carbon loss under a sequence of six rainfalls (R1-R6). These results showed that the sediment concentrations with 33% (R4) and 17% (R5) coverage downslope were significantly lower than those with coverage upslope, whereas there was no significant difference between the runoff rates of the two slopes. Thus, surface coverage at different positions induced two soil erosion regimes (deposition- and transport-dominated processes). Dynamics of the DON and DIN concentrations indicated different release processes of soil nitrogen into runoff. The DON contributed to a substantial amount of soil nitrogen loss, which accounted approximately 81% of the organic form. The SBOC is significantly correlated with sediment-enriched clay particles from the deposition-dominated processes and is higher than that from the transport-dominated processes. The DOC is significantly correlated with Rr for transport-dominated processes. These results illustrated the critical role of erosion regimes in soil organic carbon loss in dissolved or sediment-bound form. It is concluded that erosion/covered zones altered by surface coverage could produce transport- and deposition-dominated erosion regimes and consequently affect soil carbon and nitrogen loss. In addition, these results demonstrated that surface coverage pattern may efficiently control soil erosion and soil carbon and nitrogen loss.

Bifunctional poly (l-lactic acid)/hydrophobic silica nanocomposite layer coated on magnesium stents for enhancing corrosion resistance and endothelial cell responses

Biodegradable magnesium (Mg)-based vascular stents can overcome the limitations of conventional permanent metallic stents, such as late in-stent restenosis and thrombosis, but still have difficulty retarding degradation while providing adequate mechanical support to the blood vessel. We incorporated silica nanoparticles surface-functionalized with hexadecyltrimethoxysilane (mSiNP) into a poly (l-lactic acid) (PLLA) coating as a physical barrier to disturb the penetration of the corrosive medium as well as a bioactive source that releases silicon ions capable of stimulating endothelial cells. The corrosion resistance and biocompatibility of this bifunctional PLLA/mSiNP nanocomposite coating were investigated using different weight ratios of mSiNP. The nanocomposite coating containing more than 10 wt% of the mSiNP (PLLA/10mSiNP and PLLA/20mSiNP) significantly delayed the corrosion of the Mg substrate and exhibited favorable endothelial cell responses, compared to the pure PLLA coating. Specifically, the calculated corrosion rates of PLLA/10mSiNP and PLLA/20mSiNP decreased by half, indicating the durability of the coating after immersion in simulated body fluid for 12 days. Based on the in vitro cellular response, the incorporation of the mSiNPs into the PLLA coating significantly improved the endothelial cell responses to the Mg substrate, showing better initial cell surface coverage, migration, and proliferation rate than those of pure PLLA. These results indicate that the PLLA/mSiNP nanocomposite coatings have significant potential to improve the corrosion resistance and vascular compatibility of biodegradable Mg-based vascular stents.

Event-driven Simulation of Multi-scale Dropwise Condensation

Simulation of the multi-scale dropwise condensation on hydrophobic/superhydrophobic surfaces is of great significance for exploring condensation mechanism and guiding related engineering applications. However, the computational time cost of the conventional time-driven simulation is very expensive because the dropwise condensation covers multiple temporal and spatial scales and involves various behaviors between droplets. Here, an event-driven simulation method is proposed to efficiently simulate the multi-scale three-dimensional dropwise condensation with its simulation accuracy verified against the theoretical model and experimental results in literature. The dynamic octree data structure and its related algorithms are adopted to improve computational efficiency. Compared with the two-dimensional time-driven simulation, the computing efficiency of the three-dimensional event-driven simulation is improved by one to two orders of magnitude. The influence of droplet departure modes on dropwise condensation is then discussed and the results show that when droplets mainly depart through droplet jumping instead of droplet sliding, the surface coverage rate is smaller but the droplet population density and heat flux are larger. The increase of subcooling degree and nucleation density, or the decrease of critical sliding and jumping radius, can promote droplet departure and enhance condensation heat transfer, and the contribution of droplet jumping to heat flux is dominant. This work provides a new method that is efficient and reliable for multi-scale simulation of dropwise condensation and advances the understanding of dropwise condensation.

Sucessão de cultivos e indicadores da qualidade do plantio direto no Planalto Médio do Rio Grande do Sul

O sistema plantio direto (SPD) reúne o maior complexo de tecnologias conservacionistas para solos tropicais e subtropicais, entretanto muitos produtores estão adotando parcialmente estes preceitos, potencializando a degradação do mesmo. O objetivo deste trabalho foi avaliar a qualidade do SPD em uma localidade, localizada no Planalto Médio do Rio Grande do Sul, observando qual a situação atual do manejo do solo e das glebas agrícolas da região conduzidas sob SPD. Foi realizado o monitoramento do uso do solo da localidade de Linha Cristal, situada no município de Selbach, RS, bem como a avaliação de glebas agrícolas que representassem diferentes manejos ali observados, além de uma mata nativa servindo de referência. Para isso, nestas glebas foram determinados os aportes de fitomassa seca (FMS) e o índice de cobertura (IC) da superfície do solo, a densidade (Ds), densidade crítica (Dsc) e grau de compactação (GC) do solo, além dos teores de matéria orgânica do solo (MOS). A análise estatística consistiu em análises univariadas (média e desvio padrão), já os resultados entre os teores de MOS e a Ds, também foram submetidos à análise de regressão. A área cultivada apresentou baixa diversidade de culturas no período de verão, predominando a soja (88,6%). Maior parte do milho em 2016/2017, destinou-se a produção de silagem (59%). Os cultivos de inverno foram mais diversificados, predominando a cultura do trigo, cevada, aveia branca e aveia preta. As médias anuais de FMS adicionada ao solo (13.147 e 11.508 kg/hectare/ano) estiveram acima do mínimo para manter os níveis de MOS estipulado pela literatura (9.000 kg/hectare/ano). As glebas agrícolas apresentaram a camada de 7-14 centímetros mais densa, onde apenas uma das glebas apresentou valor de Ds inferior a Dsc. Houve correlação linear inversa entre Ds e MOS, onde as áreas que continham maiores teores de MOS, apresentavam menores Ds.

Synthesis of 3D Dendritic Gold Nanostructures Assisted by a Templated Growth Process: Application to the Detection of Traces of Molecules.

Complex architectures like 3D gold dendritic nanostructures were synthesized by an in situ templated growth method using a thin film of a block copolymer [polystyrene-b-poly(4-vinylpyridine)] deposited onto silicon substrates. The overall study has demonstrated the strong link between the morphology, size, and distribution of the structures and the synthetic physicochemical parameters, such as pH, reaction temperature, concentration, and nature of reactants. A nonequilibirum state of the medium has been required to create a fractal growth of the gold structures onto a prepatterned gold-seeded surface and has led to a better control of the structures' surface coverage rate. Those as-prepared nanodendrites have also exhibited high electrocatalytic activity toward a significant enhancement factor, as well as important sensitivity, thanks to tip effects. The electrochemical experiment results have demonstrated efficient adsorption and quantification of very low traces of specific molecules like glutathione or hexadecanethiol.

Determination of rainfall effects on kaolin clay coverage rates used in prevention plant from sunburn

Sunburn, which is an important problem in agricultural products grown in arid and semi-arid regions, causes economic losses of up to 40-60% in some years. Sunburn occurs as a result of overheating of the surfaces of fruits exposed to high air temperature and solar radiation from the sun. Increase in the temperature stress for plants is observed during months of high temperature, this is one of the main reasons for many negative conditions (changes in fruit colour, cell death in plants, etc.) in fruits and leaves. While the shelf life of damaged agricultural products is shortened, deterioration is observed even in the storage stage. Today, different applications are made to reduce the sunburn in many kinds of fruits and sunburn damage can be significantly reduced as a result of these applications. For this purpose, it was aimed to reduce the temperature on the leaf surface by the application of kaolin clay (Trade name; Güneş Stop) applied to the plant surface at the beginning of the season. In the study; eight different concentrations of kaolin clay with tree application volume were applied and after the application, leaf samples of the citrus trees were taken from the predetermined regions, and the coverage rate was measured in an image processing program. From 8 different regions, 15 pieces of leaf were randomly taken from each region. The same process was carried out again by collecting leaf samples from the same regions after the rain; thus, the performance analysis of kaolin clay was determined after the rainfall. As a result of kaolin clay application; according to the results of image analysis of average leaf surface coverage rates obtained by regions and after the rainfall, the results obtained from the same regions showed that kaolin clay was washed at a rate of 39.64% with precipitation.

Electrochemical Immunosensor Based on Highly Sensitive Amino Functionalized Graphene Nanoplatelets-Modified Screen Printed Carbon Electrode

We presented here the development of an immunosensor based on graphene nanoplatelets-modified screen printed carbon electrode (SPCE) with incorporated rabbit IgG on the amino functionalized surface area. In order to improve sensitivity of working electrode, graphene-nanoplatelets solution was fabricated onto surface carbon working electrode. The effect of different (3-aminopropyl) triethoxysilane (APTES) concentrations (0.125, 0.5, 2 and 8% (v/v)) and incubation time of silanization (30, 60 and 90 min) were studied and compared. An electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize our immunosensor based. It is showed that the optimum APTES concentration which provides higher surface coverage and electron transfer rate was 2% concentration (v/v) at 60 min of incubation time. The modified surface was then evaluated by measuring immobilized rabbit IgG via indirect assay using horseradish peroxidase labelled secondary antibody. The optimum detection immobilized IgG was 0.05 mg/mL. These results indicate the potential for amino functionalized graphene nanoplatelets-modified SPCE in detecting protein biomarkers.

Polarity effects of asphaltene subfractions on the stability and interfacial properties of water-in-model oil emulsions

Asphaltenes can adsorb at the interface between crude oil and produced water and form a defensive interfacial layer to stabilize emulsions. This paper details the effects of the polarities of asphaltene subfractions on emulsion stability and interfacial properties. Asphaltene subfractions with different polarities were first obtained by a solvent-precipitation method, followed by the characterization of their molecular structures and dispersive states in the model oil. The results show that the subfractions with lower polarity contain a higher proportion of aliphatic groups, which benefits oil compatibility, thus leading to a better dispersive state and weaker aggregation tendency. Then, the stabilities of the emulsions prepared with these subfractions were explored at different concentrations. The emulsion stability worsens as polarity weakens at 500 ppm. However, at a concentration of 5000 ppm, the emulsion stability increases first with a polarity decrease, reaches a peak, and then decreases. The adsorption behavior and interfacial structural strength are detected through dynamic interfacial tension and dilational viscoelastic experiments. The subfractions with lower polarities exhibit better dispersion in the model oil, allowing for higher rates of absorption. The dilational modulus and emulsion stability depend on the migration rate and surface coverage of the subfractions and share similar trends with changes in polarity. With an increase in the polarity of the subfractions, the surface coverage and migration rate have reverse contributions on the dilational modulus and emulsion stability. Additionally, the contributions become more obvious after asphaltene aggregation.

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.

Reduced bacterial adhesion on zirconium-based bulk metallic glasses by femtosecond laser nanostructuring.

As high-performing materials, bulk metallic glasses have attracted widespread attention for biomedical applications. Herein, the bacterial adhesion properties of femtosecond laser-nanostructured surfaces of four types of zirconium-based bulk metallic glasses are assessed. Laser-induced periodical surface structures and nanoparticle structures were fabricated by femtosecond laser irradiation under different energy intensities (0.23 and 2.3 J/mm2). Surface topography, roughness, wettability, and surface energy were investigated after femtosecond laser irradiation and the surface bacterial adhesion properties were explored using Escherichia coli and Staphylococcus aureus as respective representatives of Gram-negative and Gram-positive bacteria. 4',6-Diamidino-2-phenylindole fluorescence staining was used to characterize and assess the bacterial surface coverage rate. The in vitro cytotoxicity of polished and laser-nanostructured surfaces was investigated using MC3T3-E cells. The obtained results demonstrate that femtosecond laser surface nanostructuring retained the amorphous structure of zirconium-based bulk metallic glasses and led to an obvious decrease in bacterial adhesion compared with polished surfaces. The inhibition of bacterial adhesion on laser-induced periodical surface structures was greater than on nanostructured surfaces after 24 h of bacterial incubation. In addition, femtosecond laser nanostructuring did not have an apparent effect on the cytotoxicity of zirconium-based bulk metallic glasses.