Current-Induced Changes of Surface Morphology in Printed Ag Thin Wires

BackgroundCellulose amorphogenesis, described as the non-hydrolytic “opening up” or disruption of a cellulosic substrate, is becoming increasingly recognized as one of the key steps in the enzymatic deconstruction of cellulosic biomass when used as a feedstock for fuels and chemicals production. Although this process is thought to play a major role in facilitating hydrolysis, the lack of quantitative techniques capable of accurately describing the molecular-level changes occurring in the substrate during amorphogenesis has hindered our understanding of this process.ResultsIn this work, techniques for measuring changes in cellulose accessibility are reviewed and a new quantitative assay method is described. Carbohydrate binding modules (CBMs) with specific affinities for crystalline (CBM2a) or amorphous (CBM44) cellulose were used to track specific changes in the surface morphology of cotton fibres during amorphogenesis. The extents of phosphoric acid-induced and Swollenin-induced changes to cellulose accessibility were successfully quantified using this technique.ConclusionsThe adsorption of substructure-specific CBMs can be used to accurately quantify the extent of changes to cellulose accessibility induced by non-hydrolytic disruptive proteins. The technique provided a quick, accurate and quantitative measure of the accessibility of cellulosic substrates. Expanding the range of CBMs used for adsorption studies to include those specific for such compounds as xylan or mannan should also allow for the accurate quantitative tracking of the accessibility of these and other polymers within the lignocellulosic biomass matrix.

Age-related changes in the surface morphology of the central sulcus

Surface degradation process affected by heterogeneity in nano-titanium dioxide filled acrylic urethane coatings under accelerated UV exposure

In this study, a continuous UV/ozone surface modification process of polymeric fiber for the production of continuous-fiber-reinforced polymer based composite has been proposed. The gas phase photo-reactor, using the conventional low-pressure mercury lamps as UV sources, and the economically-made ozone generator were designed and constructed. Polyethylene terephthalate (PET) yarns and epoxy resin were chosen to be reinforcement and matrix in our composite system, respectively. Five combinations of UV light and gas species, i.e. UV/N2, UV/air, UV/02, UV/air + 03, and UV/03 + 02, for treating PET yarn were performed. The effects of exposure time, i.e. 2, 5, and 10 min, in the reactor of the fiber surface to each treatment were also studied by varying the pull speed of the pulling mechanism. The unidirectional tensile testing specimens were prepared by arrangement PET samples into specific designed casting mold.The treatments led no significant effects to the tensile properties, maximum load and elongation to break, of PET samples. The samples were analyzed by scanning electron microscope (SEM) to determine the surface morphology, and by energy dispersive x-ray analysis (EDX) to determine the surface composition. All treatments, there were no surface morphology changes observed. The EDX results showed that the effect of the treatment to surface composition depend on concentration of reactive species in the gas, i.e. ozone, molecular oxygen, atomic oxygen, and singlet oxygen. UV/02 + 03 treatment gave the highest value of oxygen uptake (6.6 %).Tensile test of resulted composites was investigated to determine the effectiveness of the treatment on the mechanical properties of the composite properties. The most effective condition of the treatment was 5 min UV/02 + 03, which improved 63 % of tensile strength, 175 % of elongation to break, and 325 % of toughness, in comparison to nontreated PET composite. However, 5 min UV/air + 03 was found to be most cost-effective condition because there was no need for supply oxygen at this condition. The 5 min UV/air + 03 treatment improved 52 % of tensile strength, 126 % of elongation to break, and 270% of toughness, compared to nontreated PET composite.

The purpose of this study was to evaluate, using scanning electron microscopy (SEM), the morphological and structural changes of the enamel induced by three bleaching agents namely old McInnes solution, modified McInnes solution and 10% carbamide peroxide gel at different time intervals. Fifteen freshly extracted noncarious human central incisors with intact enamel surface were selected. The teeth were sectioned at the cementoenamel junction separating the crown portion from the root using a diamond separating disk. Following this, the samples were subjected to three different bleaching agents: Group 1: Old McInnes solution, group 2: modified McInnes solution and group 3: 10% carbamide peroxide for a period of 15, 30 and 60 minutes, 24 and 30 hours time interval. The sample stubs were subjected to scanning electron microscope and were photographed at 2000 and 10,000 magnifications. The present study revealed no indication of either etching or significant change in surface morphology of enamel when evaluated under scanning electron microscope after 6 weeks treatment with various bleaching agents. Morphological alterations in bleached enamel are both concentration and time dependent.

Surface morphology is a key factor that determines the quality of laser-based micromachining processes. However, the governing laws of surface morphology in the laser processing process are yet to be clarified, and optimization of processing parameters has to rely on trial and error. Specifically, under multiple-pulse irradiation, it has been difficult to quantify the evolution of the surface morphology because the surface morphology changes with each pulse irradiation, and the ablation process changes accordingly. In this study, we investigated the evolution of surface morphology under femtosecond laser irradiation. Copper and silicon were used as targets, whose surface morphology changes exhibited seemingly opposite behaviors with respect to fluence. Using thousands of datasets, we obtained an evolution equation for surface morphology in terms of surface area, which acts as a good probe of the residual surface energy after ablation. Our model successfully quantifies the cumulative effect of multiple-pulse irradiation on surface morphology changes.

Silicon carbide (SiC) and its composites are candidate materials for the blanket components and for the first wall in a fusion reactor. If the SiC is used without any armor materials for the first wall, it is exposed by helium (He) plasma as well as hydrogen plasma. Characteristic surface morphology changes are reported for various materials by He plasma exposure. Thus, we exposed SiC specimens to He or simultaneous deuterium (D) and He (D + He) plasma by various conditions and then observed surface morphology changes by SEM. As a result, needle-like structures and whiskers-like structures at the tip were formed in He plasma and D + He irradiation, while only needle-like structures were formed in D plasma. Therefore, it indicated that the effects of He were attributed to form whiskers-like structures. Although the structures are different among He plasma, simultaneous D + He plasma and D plasma irradiations, sputtering is considered to be a dominant process for the formation of the structure formation. However, the effects of He atoms in the structure could also be attributed to form whiskers-like structures.

In‐situ atomic force microscopy studies of electromigration in 4 μm wide by 1 μm thick electroplated Au wires were performed. The topographical features that develop on a sub‐micrometer length scale were studied for current densities up to 7.5×106 A/cm2 and temperatures up to 280 °C for time intervals ranging from a few minutes up to a few days. Scanning probe images of the same area taken before, during, and after current stressing reveal substantial changes in surface morphology. Both hillock growth and void formation have been observed in situ. Time lapse AFM images can be pieced together to give a microscopic picture of mass flow due to electromigration. These studies show that changes in surface morphology caused by electromigration can now be quantitatively characterized with high resolution from the scanning probe images.

In recent years, flexible electronic devices have become a hot topic of scientific research. These flexible devices are the basis of flexible circuits, flexible batteries, flexible displays and electronic skins. Graphene-based materials are very promising for flexible electronic devices, due to their high mobility, high elasticity, a tunable band gap, quantum electronic transport and high mechanical strength. In this article, we review the recent progress of the fabrication process and the applications of graphene-based electronic devices, including thermal acoustic devices, thermal rectifiers, graphene-based nanogenerators, pressure sensors and graphene-based light-emitting diodes. In summary, although there are still a lot of challenges needing to be solved, graphene-based materials are very promising for various flexible device applications in the future.

Biocompatibility and Cytotoxicity of Pulp-Capping Materials on DPSCs, With Marker mRNA Expressions

In this work, we assess the surface modifications induced on W samples following exposure to He and He/H2 radiofrequency plasmas in hollow cathode discharge configuration. Our study addresses issues that relate to the use of W in next-generation fusion reactors and, therefore, the investigation of W surface degradation following exposure and heating by plasmas to temperatures above 1000 °C is of practical importance. For these experiments, we used commercially available tungsten samples having areas of 30 × 15 mm and 0.1 mm thickness. The hollow cathode plasma was produced using a radiofrequency (RF) generator (13.56 MHz) between parallel plate electrodes. The W samples were mounted as one of the electrodes. The He and He/H2 plasma discharges had a combined effect of heating and bombardment of the W surfaces. The surface modifications were studied for discharge powers between 200 and 300 W, which resulted in the heating of the samples to temperatures between 950 and 1230 °C, respectively. The samples were weighed prior and after plasma exposure, and loss of mass was measured following plasma exposure times up to 90 min. The analysis of changes in surface morphology was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, optical emission spectra of the respective plasmas were recorded from the region localized inside the hollow cathode gap. We discuss the influence of experimental parameters on the changes in surface morphology.

Ultraviolet (UV) and infrared (IR) lasers can be used to specifically target protein, water, and mineral, respectively, in dental hard tissues to produce varying changes in surface morphology, permeability, reflectivity, and acid resistance. The purpose of this study was to explore the influence of laser irradiation and topical fluoride application on the surface morphology, permeability, reflectivity, and acid resistance of enamel and dentin to shed light on the mechanism of interaction and develop more effective treatments. Twelve bovine enamel surfaces and twelve bovine dentin surfaces were irradiated with various combinations of lasers operating at 0.355 (Freq.-tripled Nd:YAG (UV) laser), 2.94 (Er:YAG laser), and 9.4 μm (CO2 laser), and surfaces were exposed to an acidulated phosphate fluoride gel and an acid challenge. Changes in the surface morphology, acid resistance, and permeability were measured using digital microscopy, polarized light microscopy, near-IR reflectance, fluorescence, polarization sensitive-optical coherence tomography (PS-OCT), and surface dehydration rate measurements. Different laser treatments dramatically influenced the surface morphology and permeability of both enamel and dentin. CO2 laser irradiation melted tooth surfaces. Er:YAG and UV lasers, while not melting tooth surfaces, showed markedly different surface roughness. Er:YAG irradiation led to significantly rougher enamel and dentin surfaces and led to higher permeability. There were significant differences in acid resistance among the various treatment groups. Surface dehydration measurements showed significant changes in permeability after laser treatments, application of fluoride and after exposure to demineralization. CO2 laser irradiation was most effective in inhibiting demineralization on enamel while topical fluoride was most effective for dentin surfaces. Lasers Surg. Med. 49:913-927, 2017. © 2017 Wiley Periodicals, Inc.

Atomic force microscopy (AFM) has been employed to probe the detailed surface morphology of chemically polished and electropolished zirconium substrates. Whilst the results are qualitatively similar to those from transmission electron microscopy of carbon replicas of the treated surfaces, AFM allows ready quantification of the surface morphology in three dimensions. Furthermore changes in surface morphology, associated with growth of relatively thin anodic oxide films on the respective surfaces, have been revealed by AFM. The development of a subtle roughness was displayed after anodizing chemically polished zirconium, whilst anodizing an originally electropolished surface revealed no changes in surface morphology. Such behaviour is related to the film growth mechanism on the respective substrates. Non-uniform film growth on the chemically polished zirconium arises through the presence of preferred paths for ionic conduction within the fluoride-contaminated, amorphous, anodic film developed initi...

The present study is aimed at investigating the change in surface morphology, hydraulic behaviour and sorption capability of two locally available Indian bentonites in the presence of different lead (Pb2+) concentrations. FESEM, FTIR, and EDX studies were conducted to analyse the change in surface morphology, alteration in FTIR pattern and decrease in exchangeable cation in both the bentonites before and after sorption of Pb2+. The tests were conducted in a batch mode to optimise operation parameters; pH, initial concentration, adsorbent dosage, and contact time. Equilibrium isotherm and sorption kinetics of both the bentonites were studied using various isotherm as well as kinetic models. The equilibrium data for both the bentonites were found to be the best fit for the Freundlich model. Both the bentonites followed Pseudo-second order equation. Hydraulic conductivity analysis illustrates that with the rise in Pb2+ concentration, the hydraulic conductivity increased for both the bentonite. The experimental evidence revealed that bentonite having high cation exchange capacity (CEC), swelling behaviour and high specific surface area (SSA) exhibits higher adsorption and heavy metal removal at 2000 mg/L of initial concentration of Pb2+ solution.

Background and Objective The potential benefits of the effects of lasers on dental tissues have yet to be realized but may be brought closer through the availability of a suitable laser. The objective of this project is to examine the surface morphological changes resulting from hydrogen fluoride (HF) laser radiation on tooth and restorative material surfaces. Study design/Materials and Methods: A hydrogen fluoride laser emitting at 2.9 μm is used to interact with a range of dental hard tissue and restorative materials. The surface morphological changes induced by 100 mJ pulses of <1 μs duration is studied using a SEM. Results The irradiated surfaces displayed microstructures similar to those of a mechanically fractured surface with no evidence of melting. Conclusion This study suggests that tissue is removed by micro-explosion, leaving a surface free from thermal damage with surface characteristics that would appear to facilitate the adhesion of restorative materials. Lasers Surg. Med. 21:1–6, 1997 © 1997 Wiley-Liss, Inc.