Scanning Electron Microscopy Image Analysis Research Articles

A multiscale microstructural characterization of SiO2-Al2O3 foams

Recent advances in engineering of porous ceramics have enabled the ability to fabricate silica-alumina foams (SAF) with controllable porosity. In an earlier investigation (doi.org/10.1016/j.ceramint.2020.01.042), we examined the thermophysical properties, as well as the efficacy of Na-activated SAF foams for thermal insulation applications. As an important follow-up, in this work, we focus on microstructural characterization of SAF foams and provide fundamental insights into the chemical and structural features that underlie SAF foams. In this regard, we carry out X-ray micro computed tomography (μCT), in conjunction with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD), and nuclear magnetic resonance (NMR) spectroscopy. μCT images clearly show the closed cell nature of the foams; in addition, the ratio of average pore-size to average strut thickness decrease with increasing mass density of the foams. An analysis of SEM images demonstrates that the compositional and structural features of both the strut walls and the interior walls of the pores are very similar, primarily consisting of inorganic silica and alumina particles. SEM data also indicate that the SAF foams demonstrate a hierarchical pore structure. Further insights obtained from EDX maps, XRD data, and NMR spectra, clearly indicate the presence of a crystalline ‘film’ phase (NaAlSiO4) in close proximity with the inorganic particles. We hypothesize that the observed NaAlSiO4 phase is formed due to the high pH conditions pertaining to the synthesis protocols and serves as a binder phase between constituent silica particles.

Structural and weak antilocalization analysis of topological single-crystal SnSb2Te4

Here, we report successful single crystal growth of SnSb2Te4 using the self-flux method. Unidirectional crystal growth is confirmed through X-ray Diffraction (XRD) pattern taken on mechanically cleaved crystal flake while the rietveld refined Powder XRD (PXRD) pattern confirms the phase purity of the grown crystal. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) image and Energy Dispersive X-Ray analysis (EDAX) confirm crystalline morphology and exact stoichiometry of constituent elements. Vibrational Modes observed in Raman spectra also confirm the formation of the SnSb2Te4 phase. DC resistivity (ρ-T) measurements confirm the metallic character of the grown crystal. Magneto-transport measurements up to±5T show a non-saturating low magneto-resistance percentage (MR%). V-type cusp and Hikami Larkin Nagaoka (HLN) fitting at lower field confirms the Weak Anti-localization (WAL) effect in SnSb2Te4. Density Functional Theory (DFT) calculations were showing topological non-trivial electronic band structure. It is the first-ever report on MR study and WAL analysis of SnSb2Te4 single crystal.

Effects of decontamination protocols on the aesthetic, morphological, and material composition of preformed paediatric crowns

Preformed crowns (PCs) are exposed to potentially infectious bodily fluids during the trial fit; however, whether they can be safely re-used remains uncertain. This study determined the effects of decontamination methods on various PCs. The key criteria examined were aesthetic, morphological, and elemental characteristics. This is a laboratory-based experimental study. Stainless steel, pre-veneered stainless steel, and zirconia PCs underwent either: (a) ultrasonic cleaning with EmPower® followed by steam sterilisation, (b) thermal disinfection in an instrument washer with Asepti® Neutraliser/Asepti® followed by steam sterilisation, or (c) immersion in an ortho-phthalaldehyde (OPA) instrument-level disinfectant. The methods were performed for 1, 5, or 10 cycles, and scanning electron microscopy (SEM); red, green, and blue (RGB) value; and luminosity value were tracked (using a histogram of individual colour reference chips in Adobe Photoshop® ) to assess colour changes, and energy-dispersive X-ray (EDX) spectroscopy to characterise the material composition. Pre-veneered stainless steel crowns showed isolated zones of darkening with loss of luminosity and variations in green and blue values after ultrasonic or thermal washer disinfection combined with steam autoclaving at 5 and 10 cycles. No changes occurred with OPA. Both SEM imaging and EDX analysis identified no changes to crown materials from any of the three reprocessing methods. Reprocessing protocols need to reflect the differing responses of various types of PCs. Repeated steam sterilisation causes slight aesthetic alterations by way of colour instability and loss of luminosity to pre-veneered stainless steel crowns, but no issues with stainless steel or zirconia PCs.

Quality Assessment of Five Randomly Chosen Ceramic Oral Implant Systems: Cleanliness, Surface Topography, and Clinical Documentation.

After some initial setbacks in the 1970s, ceramic implants seem to be a promising alternative to titanium implants. Since the surface of an implant system represents the interface to surrounding biologic structures, the study focuses on cleanliness and surface topography. Clinical documentation of the corresponding systems completes the picture and allows a better evaluation of zirconia implant systems. Five different ceramic implant systems were selected randomly and purchased via blind-shopping: Z5s (Z-Systems), ZiBone (COHO), W implant (TAVDental), ceramic. implant (vitaclinical), and BioWin!/Standard Zirkon Implantat (Champions-Implants/ZV3 system). Three samples of each implant system underwent scanning electron microscopy (SEM) imaging and elemental analysis (EDS). Where appropriate, subsequent Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) was performed to identify the chemical nature of impurities. Surface topography was evaluated, and a search for clinical trials in the PubMed database, on the websites and by written request to each dental implant manufacturer, was performed. Surfaces of Champions implants (ZV3) and Z-Systems implants were relatively clean, whereas the other investigated surfaces of vitaclinical, TAV Dental, and ZiBone implants all displayed organic contaminations on their surfaces. Four of the investigated ceramic implants showed a moderately rough implant surface. Only the vitaclinical ceramic.implant had minimal surface roughness. Three ceramic designs-vitaclinical, ZV3, and Z-Systems-had clinical trials documented with up to 3 years of follow-up and results varying between 82.5% and 100% survival. TAV Dental W and ZiBone implant systems lacked properly conducted clinical recording of results. The results of this study showed that it is technically possible to produce zirconia implants that are largely residue-free. On the other hand, the variety of significant residues found in this analysis raises concerns, as contamination may lead to undesirable biologic effects. The lack of clinical studies in peer-reviewed journals does not seem to be relevant for the approval of marketing, nor does the lack of surface cleanliness. In the authors' opinion, a critical analysis of these aspects should be included in a more stringent future analysis prior to the marketing of oral implant systems.

Improving and evaluating the adhesion and stability of make-up by enhancing the affinity between skin/make-up layer.

Make-up clumps, bumps and collapses are the three factors that determine how well make-up has been performed. The purpose of this study is to reduce the three factors mentioned above by using amphiphilic substances to increase the affinity between the skin and the make-up layer. In addition, it aims to evaluate the improvement of the make-up layer by developing an objective make-up layer evaluation method. Experiments were performed in an attempt to increase the affinity between the skin and the make-up layer by minimizing the difference in surface energy between the two. Multiple types of artificial skin (leather and bio-skin) were used and treated to form the liquid foundation layer. Qualitative evaluation of the make-up layer was conducted by analyzing the surface, cross-section, and fracture area of the make-up layer, using the evaluation method proposed in this study. After applying this method and taking measurements by 3D surface analysis, the surface roughness of the make-up layer reduced by 46%, and the maximum thickness of the make-up layer reduced by about 50% in comparison with the control group (method not applied). In the case of the make-up layer to which this method was applied, two-dimensional cross-sectional Scanning Electron Microscope (SEM) image analysis confirmed that agglomeration was reduced, and the thickness of the make-up layer was also reduced by an average of 54%. According to this result, the technique of increasing the affinity between the skin and the make-up layer reduces the level of aggregation of make-up and encourages the formation of a uniform and thin make-up layer. Also, the fracture area after motion simulation was reduced by 33%. These results indicate that the method of increasing the affinity between skin/make-up membranes positively affects the formation of a uniform make-up layer. Increasing the affinity by reducing the surface energy between the skin and the make-up layer plays an important role in forming a thin and uniform make-up layer by improving the problems of lifting, agglomeration, and collapse of the make-up. In addition, it has been confirmed that through this method, the quality of consumer experience related to make-up satisfaction can be improved. The results show that objective analyses of make-up help the understanding of the quality of consumer experience on make-up.

Determination of the yield, mass and structure of silver patches on colloidal silica using multiwavelength analytical ultracentrifugation

Anisotropic nanoparticles offer considerable promise for applications but also present significant challenges in terms of their characterization. Recent developments in the electroless deposition of silver patches directly onto colloidal silica particles have opened up a simple and scalable synthesis method for patchy particles with tunable optical properties. Due to the reliance on patch nucleation and growth, however, the resulting coatings are distributed in coverage and thickness and some core particles remain uncoated. To support process optimization, new methods are required to rapidly determine patch yield, thickness and coverage. Here we present a novel approach based on multiwavelength analytical ultracentrifugation (MWL-AUC) which permits simultaneous hydrodynamic and spectroscopic characterization. The patchy particle colloids are produced in a continuous flow mixing process that makes use of a KM-type micromixer. By varying the process flow rate or metal precursor concentration we show how the silver to silica mass ratio distribution derived from the AUC-measured sedimentation coefficient distribution can be influenced. Moreover, through reasoned assumptions we arrive at an estimation of the patch yield that is close to that determined by arduous analysis of scanning electron microscopy (SEM) images. Finally, combining MWL-AUC, electrodynamic simulations and SEM image analysis we establish a procedure to estimate the patch thickness and coverage.

The optimization of hydrothermal synthesis of MnxCo3‐xO4/GC catalyst for low temperature NH3‐SCR /using design of experiments

AbstractBACKGROUNDIn this study, a new catalyst for low‐temperature selective catalytic reduction of NOx with NH3 (NH3‐SCR) were prepared by using glucose and discussed optimization of the synthetic conditions of MnxCo3−xO4/GC (glucose carbon) catalysts by using the design of the experiments. A response surface methodology (RSM) combined with the central composite design (CCD) was applied to model and optimize the synthetic conditions.RESULTSAs a result, the optimum NOx conversion of 95.6% and N2 selectivity of 81.8% were obtained at Mn/Co 2.1, urea/(Mn + Co) mole ratio 11.5, glucose/(Mn + Co) mole ratio 8.9, preparation temperature 175.4 , and calcination temperature 376.3 . The SEM (Scanning electron microscope) image and EDS (Energy Dispersive Spectroscopy) analysis showed that metal oxides of Mn and Co were uniformly accumulated on the carbon microsphere surface. XRD (X‐ray diffraction) patterns showed that CoCo2O4 content in the catalyst increased with the increase of the glucose/(Mn + Co) mole ratio, which reduced the interaction between Mn and Co, and played a negative impact on catalytic performance. FTIR (Fourier‐transform infrared) spectra showed that the catalyst surface in the optimum preparation conditions had more oxygen‐containing functional groups and that the excessive glucose carbon was unfavourable to catalytic performance. For urea/(Mn + Co), as urea/(Mn + Co) decreased, in addition to the decrease in Mn and Co content in the catalyst due to the decrease in precipitant, CoCo2O4 content in the catalyst also increased and oxygen‐containing functional groups decreased, both of which resulted in the decrease of the catalytic performance.CONCLUSIONThe H2‐TPR and NH3‐TPD results demonstrated that the catalyst prepared in the optimum conditions possessed a stronger reducing ability, more acid sites, and stronger acid strength than the other. © 2021 Society of Chemical Industry

Application of Fiber Made from Bark of Salak (Salacca Zalacca) Tree as Reinforcement in Polymer Matrix Composites

<p class="02abstracttext">Although Indonesia is abundant supply of salak (Salacca zalacca) fruit, bark of salak is not yet advanced utilized. This work therefore chracterized its fiber and process it into polymer matrix composites. The study was conducted using varied chemical treatments. Delignification using NaOH solution with concentration of 1%, 5%, 10% with 3 hours immersion time. Bleaching treatment was using H<sub>2</sub>O<sub>2</sub> media with varied immersion time at 30, 60 and 90 minutes. Tensile tests, impact tests, microscopic image test using scanning electron microscopy (SEM) and chemical composition test using fourier-transform infra-red (FTIR) spectroscopy were carried out in this work. This work showed that optimal delignification treatment can be found when 5% NaOH concentration was used. The corresponding ultimate tensile strength and impact strength were 25.47 MPa and 11.95 kJ/m<sup>2</sup>, respectively. The optimal bleaching treatment was 90 minutes immersion. The results of SEM image analysis showed that the salak midrib fiber composite without treatment has a lousy interface. Meanwhile, fiber with delignification treatment only has reasonable good interface and fiber with delignation treatment followed by bleaching treatment has excellent interface. FTIR test results showed that the salak midrib fiber composite without treatment had a cellulose component although hemicellulose and lignin levels still dominated. The delignification treatment had succesfully broken the lignin-specific C = O bond but still could not eliminated hemicellulose and lignin bond. In comparison, bleaching treatment reduced intensity of OH intensity, CH and CO which are typical hemicellulose and lignin functional groups. Based on the results of the study, salak midrib fiber with delignification chemical treatment using 5% NaOH for 3 hours followed by bleaching treatment using 2% H<sub>2</sub>O<sub>2</sub> for 90 minutes was the best treatment.</p>

Experiments for Enhancing Tailings Slurry Drainage and Geotechnical Performance Using Nonsegregation Flocculation and Geotextile

Abstract Pumping tailings slurry into geotextile bags is a burgeoning method employed to build tailings dams with improved tailings management. Fine contents bring great challenges for tailings stability. In this article, nonsegregation flocculation was selected for fine tailings. Experiments were carried out in three campaigns: nonsegregation flocculation of tailings slurry to reduce fine content in supernatant (low turbidity); water drainage evaluation via filtration tests, plus the measurement of capillary suction time; and the study of geotechnical properties, including hydraulic conductivity and yield strength. From the results, it is demonstrated that the tailings slurry without flocculation showed apparent particle segregation and poor drainage performance compared to tailings with nonsegregation flocculation. The yield strength with nonsegregation tailings was enhanced by two times to initial values. Scanning electron microscopy image analysis was used to check the attachment status of solid particles on geotextile surfaces after being used for filtration tests. The mechanism of enhancing geotextile drainage revealed that increased permeability and reduced geotextile pore-plugging should account for the enhanced water drainage and tailings stability. A pattern of achieving optimal drainage strategy of geotextile bag was recommended for building a tailings dam, which is to use large-sized flocs plus geotextiles with large pore sizes (up to 0.6 mm).

Experimental and numerical investigations on the failure behavior of metal skin and carbon fiber-reinforced polymer core structures considering layup and manufacturing process conditions

In this paper, the failure mechanism of metal skin (MS) and long carbon fibers reinforced core (CFRP) structures is investigated by means of tensile and bending tests, scanning electron microscope image analysis, and finite element simulations. For the failure modeling, a ductile damage model has been utilized for the MS, a traction separation model for the adhesive layers, whereas a modified Tsai-Hill criterion under the orthotropic assumption has been employed for the CFRP core. To verify the reliability of the proposed approach in predicting the failure of more complex MS-CFRP structures, experimental and numerical load-stroke curves relevant for two hat-shaped specimens, manufactured with two different MS, have been compared, showing a maximum deviation in the maximum load equal to 3.5%. The methodology proposed in this paper shows a systematic and reliable approach for the investigation of the fracture behavior of metal-composite structures, to be utilized for the design phase.

The effect of spray angle on the microstructural and mechanical properties of plasma sprayed8YSZ thermal barrier coatings

Thermal barrier coatings (TBCs) are favorable for better protection of gas turbines and aero engines at high temperatures. The TBCs were fabricated using NiCrAlY bond coat and 8% wt. yttria-stabilized zirconia (YSZ) topcoat onto the nickel-based superalloy Inconel 800 by atmospheric plasma spray. In this article, the investigation of microstructural and mechanical properties of 8YSZ TBCs with the effect of spray angle has been discussed. The microstructural and elemental analyses were conducted by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). The porosity analysis was conducted based on SEM image analysis using a gray scale threshold. Mechanical properties such as coating hardness, surface roughness, and thickness are measured by indentation, surface profilometer, and optical microscopy. The result shows the effect of the spray angle over the coating surface in terms of pores and microcracks. The influence of the spray angle leads to different grain growth resulting in the shadow region. A large number of defects and a decrease in coating hardness were observed for 60 degrees pray angle compared to the 90 degrees pray angle. A large number of defects led to developing rough surfaces, resulting in low hardness and increased porosity. The experimental results showed that the plasma sprayed 8YSZ TBC with a 90 degree spray angle can improve the durability and performance of the TBCs, as it has better microstructural and mechanical properties.

Effective adsorptive removal of anionic dyes from aqueous solution

AbstractCongo Red (CR) and Reactive Black 5 (RB5) anionic dyes were removed from aqueous solution using Porous Magnetite Fe3O4 nanospheres (PMNs) as a high‐performance adsorbent. Various methods, such as Fourier transform infrared spectroscopy and X‐ray diffraction, were used to classify the synthesized PMNs. The Brunauer Emmett‐Teller (BET) method was used to calculate the sample's high specific surface area of 143.65 m2.g‐1, as well as its pore volume and pore size. The PMNs have a very uniform spherical morphology, with an average particle size of 25.84 nm, as revealed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) image analysis. Variables such as initial pH, adsorbent dosage, contact time, and temperature were investigated to determine optimal adsorption conditions for the extraction of Congo Red (CR) and Reactive Black 5 (RB5) from aqueous solutions. The optimal pH for extracting the anionic dyes tested from water solutions was 3 and 4 for CR and RB5, respectively. The maximum adsorption potential of the CR and RB5 dyes, respectively, was 1621.59 and 1070 mg.g‐1. pH, temperature, initial concentration, contact time, salinity, and PMNs dosing were all studied in depth. Since the PMNs Zero‐charge point (pHPZC) equals 4.3, these dyes were ideal for adsorption at an acid pH. The Langmuir, Freundlich, Dubinin ‐ Radushkevich, and Temkin adsorption isotherms were used to determine adsorption results. For both dyes, the adsorption isotherm was fitted to the Langmuir model. The mean adsorption energy (Ea) for CR and RB5, respectively, is 20.2 and 24.8 kJ.mol‐1, suggesting a chemisorption mechanism. The kinetics of adsorption was discovered to adopt a pseudo‐second‐order kinetic model. Thermodynamic experiments confirmed that the adsorption mechanism is endothermic and spontaneous. They experimented with ethanol as a solvent for desorption of adsorbed anionic dyes.

Scanning Electron Microscopic Assessment of Stent Coating Integrity in Jailed Wire Technique for Bifurcation Treatment.

Objectives To assess the impact of different guidewires on stent coating integrity in jailed wire technique (JWT) for bifurcation treatment. Background JWT is commonly adopted to protect side branch in provisional one-stent strategy for coronary bifurcation lesions. However, this technique may cause defects in stent coatings. The degree of coating damage caused by different types of jailed wires remains unknown. Methods A fluid model with a bifurcation was established to mimic the condition in vivo. One-stent strategy was performed with three types of guidewire (nonpolymer-jacketed wire, intermediate polymer-jacketed wire, and full polymer-jacketed wire) tested for JWT. Scanning electron microscopy (SEM) was used to evaluate stent coating integrity and wire structure. The degrees of coating defects were recorded as no, slight, moderate, and severe defects. Results A total of 27 samples were tested. Analyses of SEM images showed a significant difference in the degree of coating damage among the three types of wire after the procedure of JWT (P < 0.001). Nonpolymer-jacketed wire could inevitably cause a severe defect in stent coatings, while full polymer-jacketed wire caused the least coating damages. Besides, there were varying degrees of coil deformation in nonpolymer-jacketed wires, while no surface damage or jacket shearing was observed in full polymer-jacketed wires. Conclusions Although nonpolymer-jacketed wire has long been recommended for JWT, our bench-side study suggests that full polymer-jacketed wire may be a better choice. Further clinical studies are needed to confirm our findings.

Deformation of Needle Tips During Facial Soft Tissue Filler Injections: An Electron-Microscopic Study.

Injectable soft tissue fillers are used on a global scale for a variety of aesthetic indications. Despite their widespread use, there is a dearth of information regarding needle deformation following injection procedures. Repeated injections with the same needle could lead to progressive needle tip deformation, potentially resulting in decreased precision and increased patient discomfort. The objective of this study was to quantify the magnitude of needle tip deformation utilizing scanning electron microscopy (SEM) image analysis. An observational study was performed evaluating 4 differently sized needles following soft tissue filler injections for 5 different aesthetic indications (zygomatic arch, infraorbital, midcheek, nasolabial sulcus, and perioral) in patients aged 36 to 64 years. Following treatment, each needle was visualized and imaged through SEM, and the percentage of deformation in relation to the total amount of needle tip surface was calculated. The factor most influencing needle tip damage was revealed to be the number of injection passes, ie, dermal transitions. Per injection procedure, an increase in needle tip damage of 4.7% occurred. Touching the bone deformed the needle tip by 9.6% and an increase in needle size resulted in 0.13% more damage. To the authors' knowledge, this is the first SEM investigation to provide objective evidence for the deformation of needle tips after repeated facial soft tissue filler injections. These data may help improve patient safety and comfort during these minimally invasive procedures.

Effect of the drying process on the color change, fissure development, and morphology of fortified rice kernels

AbstractFortified rice kernels (FRK) were manufactured using extrusion technology and dried in a hot air tray dryer. The present study was aimed to find the effect of air temperature (40, 50, 60, and 70°C) and the drying time (0–160 min) at 1.0 m/s air velocity on color attributes of FRK. The increase in temperature and time decreased the L* and WI and increased the a*, b*, and ΔE values of FRK. The kinetic modeling suggested a fairly good fitting of the quadratic model for ΔE and WI. The Page model (R2 ≥ 0.9512, RMSE ≤ 0.0556, and χ2 ≤ 0.0037), as an alternate approach, showed the best fitting to predict the color change ratio of FRK. For fissure and morphological analysis, the FRK were dried to a final moisture content of 12–13 %wb at each drying temperature. The results revealed that the drying at 50–70°C formed fissure inside the FRK and was confirmed by the X‐ray CT scan images. However, the scanning electron microscope (SEM) image analysis did not show any fissure at the surface of FRK. Thus, the lower temperature (40°C and 120 min) drying resulted in better color attributes with no fissure inside the FRK.Practical applicationsFRK are being used to blend in the normal rice in the 1:100 ratio to prepare micronutrient fortified rice. It is expected that the FRK should be indistinguishable in normal rice after blending. Color is an important parameter that could make easy detection of FRK in normal rice. This makes it necessary to match the characteristics of FRK with normal rice in terms of color, physical dimensions, and density. Moreover, fissure formation in FRK leads to disintegration during cooking. Therefore, the study's findings will help to get an idea about the color change during the commercial drying of FRK and decide the drying conditions that will not develop fissure inside the FRK.

Characterisation of TiO2-containing pearlescent pigments with regard to the European Union labelling obligation of engineered nanomaterials in food

ABSTRACT A wide range of trendy food colourants and ready-to-eat foods containing pearlescent pigments providing glitter effects is currently on the market. These pearlescent pigments consist of mica (potassium aluminium silicate) platelets generally coated with titanium dioxide and/or iron oxides. All single components are approved food additives in the European Union (EU) (E 555, E 171 and E 172). However, the European Food Safety Authority (EFSA) has stated recently, that pearlescent pigments should be evaluated as new food additives. Food grade titanium dioxide was already shown to contain a considerable fraction of nanoparticles. Thus, the question about ‘nano’-labelling of TiO2-containing pearlescent pigments according to the ‘Novel Food’ and ‘Food Information to Consumers’ regulations arose. In order to provide data for dealing with these issues, in this study four commercially available products of different food categories containing pearlescent pigments were characterised with focus on the structure, size and chemical composition of these pigments. The measurement methods used were flow particle image analysis (FPIA), static light scattering (SLS) and scanning electron microscopy (SEM) combined with energy-dispersive x-ray spectroscopy (EDX). After isolation from various food matrices, the glitter pigments could be easily identified and differentiated by fast FPIA screening from any remaining organic food matrix particles due to their typical platelet-like shape and transparency. The particle size distribution of the platelets was determined by means of SLS and found to be in the range of 8–167 µm. SEM was identified as the most suitable technique for the analysis of the nano-structured coating. For all constituent metal oxide particles (TiO2 and/or Fe2O3) a median minimum Feret diameter (Fmin) of 29.9–46.8 nm was obtained by quantitative SEM image analysis.

Experimental Investigation on Organic Matter Orientation Characteristics of Terrestrial and Marine Shale in China

As an essential component in shale, OM (organic matter) grains and their arrangements may play essential roles in affecting the anisotropy of the reservoir. However, OM grains are commonly treated as an evenly distributed isotropic medium in current studies, and few works have been done to investigate their detailed arrangement characteristics. In this study, terrestrial and marine shale samples were collected from three different shale plays in China, and the arrangement characteristics of OM grains in each sample were investigated by SEM (scanning electron microscope) image analysis. The results indicate that OM grains in shale are not evenly distributed in isotropic medium, and their directional alignment is pervasive in both marine and terrestrial shale. OM grains in shale tend to subparallel to the bedding section, and their orientation degree and controlling factors differ among different shales. OM grains in samples from terrestrial C-7(Chang-7 Formation) exhibit the strongest directionality in their arrangement, and OM grains in samples from marine LMX (Longmaxi Formation) shale in the Fuling area also exhibit strong directional alignment. While in samples from marine LMX shale in the Baojing area, their directional alignment is much weaker. Shales with high clay content, high TOC (total organic carbon), low thermal maturity, and flat reservoir structure get more OM grains parallel to the bedding section. The biogenetic texture of graptolite in marine LMX shale is the dominating factor leading to the strong directional alignment of the OM grains. However, syncline structure may disorganize the preformed directional alignment and weaken the directionality of the OM grains, which results in the OM arrangement difference between LMX samples from Fuling and Baojing. While the compaction of the layered clay particles is the dominating mechanism leading to the strong directional alignment of the OM grains in terrestrial shale samples from C-7.

Effect of pH of H2O2 solutions on the morphology and wear resistance of human dental enamel: an AFM study

Introduction Teeth whitening is a highly demanded aesthetic dental procedure to remove teeth stains and get a whiter and perfect smile. This type of treatment is usually performed by the application on the teeth surface of hydrogen or carbamide peroxides which diffuse through the external layer of the teeth, enamel [1]. Although whitening treatments improve teeth appearance, they can impair teeth health, due to the eventual degradation of the teeth tissues. This may lead to abnormal wear and weaken the tooth structure. The aim of this work is to study the effect of the pH of 30% H2O2 solutions on the surface of human enamel. Materials and methods Human molars were collected for the study with informed consents of the patients. Teeth were bleached in 30% H2O2 solution with different pH values (2, 4 and 6). All samples were submitted to 11 bleaching sessions of 10 min each with alternate periods (2 min) of exposition to blue light. Microhardness, surface roughness and topography/morphology were characterised by microindentation tests, atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively, before and after the whitening treatments. AFM scratching tests (10 × 10 µm2) were performed, using a diamond probe. After the nanowear tests, topographical images of larger areas (20 × 20 µm2) which include the scratched squares were obtained with a silicon probe. The wear mechanisms were evaluated by SEM. Acceptance of the study protocol was obtained from a local ethics committee. Results The most significant changes on enamel surface were obtained for pH = 2: the microhardness decreases, and the surface roughness significantly increases as confirmed by the SEM image analysis. A higher wear rate was observed for pH = 2 in the AFM scratching tests. SEM observation of the wear zone showed differences in the wear mechanisms, which depend on the pH. Discussion and Conclusions Enamel microhardness, surface roughness and wear resistance are affected by the pH of the bleaching solution: pH = 2 led to the most adverse effects, which was attributed to hydroxyapatite demineralisation. The study of the effect of pH in the bleaching treatments is crucial to optimise this type of procedures and avoids enamel damage.

Recycled Mortars with Ceramic Aggregates. Pore Network Transmutation and Its Relationship with Physical and Mechanical Properties

The porosity of mortars with recycled ceramic aggregates (10, 20, 30, 50, and 100% as a replacement of natural aggregate) was evaluated and analyzed using three different techniques. The results of gas adsorption (N2), Scanning Electron Microscopy (SEM) image analysis and open porosity allowed establishing the relationship between the recycled aggregate content and the porosity of these mortars, as well as the relationship between porosity and the physical and mechanical properties of the mortars: absorption, density, compressive strength, modulus of elasticity, and drying shrinkage. Using the R2 coefficient and the equation typology as criteria, additional data such as Brunauer, Emmett, and Teller (BET) surface area (N2 adsorption) established significant correlations with the mentioned properties; with SEM image analysis, no explanatory relationships could be established; and with open porosity, revealing relationships were established (R2 > 0.9). With the three techniques, it was confirmed that the increase in porosity is related to the increase in the amount of ceramic aggregate; in particular with gas adsorption (N2) and open porosity. It was concluded that the open porosity technique can explain the behavior of these recycled mortars with more reliable data, in a simple and direct way, linked to its establishment with a more representative sample of the mortar matrix.

Bioinspired Design of Novel Microscaffolds for Fibroblast Guidance toward In Vitro Tissue Building.

Porous microscaffolds (μ-scaffs) play a crucial role in modular tissue engineering as they control cell functions and guide hierarchical tissue formation toward building new functional tissue analogues. In the present study, we developed a new route to prepare porous polycaprolactone (PCL) μ-scaffs with a bioinspired trabecular structure that supported in vitro adhesion, growth, and biosynthesis of human dermal fibroblasts (HDFs). The method involved the use of poly(ethylene oxide) (PEO) as a biocompatible porogen and a fluidic emulsion/porogen leaching/particle coagulation process to obtain spherical μ-scaffs with controllable diameter and full pore interconnectivity. To achieve this objective, we investigated the effect of PEO concentration and the temperature of the coagulation bath on the μ-scaff architecture, while we modulated the μ-scaff diameter distribution by varying the PCL-PEO amount in the starting solution and changing the flow rate of the continuous phase (QCP). μ-Scaff morphology, pore architecture, and diameter distribution were assessed using scanning electron microscopy (SEM) analysis, microcomputed tomography (microCT), and Image analysis. We reported that the selection of 60 wt % PEO concentration, together with a 4 °C coagulation bath temperature and ultrasound postprocessing, allowed for the design and fabrication of μ-scaff with porosity up to 80% and fully interconnected pores on both the μ-scaff surface and the core. Furthermore, μ-scaff diameter distributions were finely tuned in the 100-600 μm range with the coefficient of variation lower than 5% by selecting the PCL-PEO concentration in the 1-10% w/v range and QCP of either 8 or 18 mL/min. Finally, we investigated the capability of the HDF-seeded PCL μ-scaff to form hybrid (biological/synthetic) tissue in vitro. Cell culture tests demonstrated that PCL μ-scaff enabled HDF adhesion, proliferation, colonization, and collagen biosynthesis within inter- and intraparticle spaces and guided the formation of a large (centimeter-sized) viable tissue construct.