External Surface Roughness Research Articles

Multichiral Mesoporous Silica Screws with Chiral Differential Mucus Penetration and Mucosal Adhesion for Oral Drug Delivery.

In the harsh gastrointestinal tract, helical bacteria with hierarchical chiral architectures possess strong abilities. Taking inspirations from nature, we developed a multichiral mesoporous silica nanoscrew (L/D-MCNS) as an efficient oral drug delivery platform by modifying the structural chiral silica nanoscrew (CNS) with L/D-alanine (L/D-Ala) enantiomers via the sequential application of a chiral template and postmodification strategies. We demonstrated that L-MCNS showed differential biological behaviors and superior advantages in oral adsorption compared to those of CNS, D-MCNS, and DL-MCNS. During the delivery, helical L/D-MCNS presenting distinctive topological structures, including small section area, large rough external surface, and a screw-like body, displayed multiple superiorities in mucus diffusion and mucosal adhesion. Meanwhile, the grafted chiral enantiomers enabled positive or negative chiral recognition with the biosystems. Once racemic flurbiprofen (FP) was encapsulated into the nanopores of L/D-MCNS (FP@L/D-MCNS), L/D-MCNS providing highly cross-linked and mesoscopic chiral nanochannels was beneficial for controlling the drug loading/release kinetics with chiral microenvironment sensitivity. Particularly, we noticed enantioselective absorption of FP in vivo, which could be attributed to the differential biological behaviors of L/D-MCNS. By simple design and regulation of the multilevel chirality of nanocarriers, L/D-MCNS can be employed for efficient oral drug delivery from the perspectives of material science, pharmacy, and bionics.

Biomechanical aging behaviour of clear aligners

Abstract Introduction The biomechanical behaviour of clear aligners can affect the clinical efficacy of tooth movement. Objectives To investigate the aging effects of clear aligners to suggest an optimal wear time from the biomechanical perspective. Methods Brand new “as-received” (0-day) clear aligners (Invisalign, Align Co., USA) were immersed in distilled water and placed in an incubator at a constant temperature of 37°C for 21 days to simulate the aging process encountered in the oral cavity. The biomechanical properties (flexural strength, translucency, surface roughness, hardness, and tensile strength) of the clear aligners were assessed each day. The flexural strength was measured using a digital tension gauge; translucency was assessed using the Vita Easyshade digital spectrophotometer; surface roughness was measured using a profilometer; hardness was measured by the indentation test; and tensile strength was measured using a universal testing machine. Results The flexural strength decreased significantly after 7 days (0.22 ± 0.01 N at 3 mm compression; 0.35 ± 0.01 N at 5 mm compression) compared with the baseline (0.26 ± 0.01 N, 0.41 ± 0.01 N, respectively) (difference = 0.15 N, p < 0.05 for both). The hardness decreased significantly after 10 days (4.37 ± 0.48 kgf/mm2) compared with the baseline (6.60 ± 0.43 kgf/mm2) (difference = 2.23 kgf/mm2, p < 0.05). No significant change was found in translucency (p = 0.38), internal surface roughness (p = 0.99), external surface roughness (p = 0.57), and tensile strength (p = 0.84) during the 21 days of simulated aging. Conclusions The flexural strength and hardness of the clear aligners decreased significantly after 7 days and 10 days, respectively. Surface roughness, translucency, and tensile strength varied little during the 21 days of artificial aging.

The Effect of 10% Carbamide Peroxide Dental Bleaching on the Physical Properties of Invisalign Aligners: An In Vitro Study.

The high aesthetic demands of patients have increased their requests to align their teeth using clear aligners, including Invisalign. Patients also want to have their teeth whitened for the same purpose; the use of Invisalign as a bleaching tray at night has been reported in few studies. However, whether 10% carbamide peroxide affects the physical properties of Invisalign is unknown. Therefore, the objective of this study was to evaluate the effect of 10% carbamide peroxide on the physical properties of Invisalign when used as a bleaching tray at night. Twenty-two unused Invisalign aligners (Santa Clara, CA, USA) were used to prepare 144 specimens to test their tensile strength, hardness, surface roughness, and translucency. The specimens were divided into four groups: a testing group at baseline (TG1), a testing group after application of bleaching material at 37 °C for 2 weeks (TG2), a control group at baseline (CG1), and a control group after immersion in distilled water at 37 °C for 2 weeks (CG2). Statistical analysis was conducted using a paired t-test, Wilcoxon signed rank test, independent samples t-test, and Mann-Whitney test to compare samples in CG2 to CG1, TG2 to TG1, and TG2 to CG2. Statistical analysis showed no statistically significant difference between the groups for all physical properties, except for hardness (p-value < 0.001) and surface roughness (p-value = 0.007 and p-value < 0.001 for the internal and external surface roughness, respectively), which revealed a reduction in hardness values (from 4.43 ± 0.86 N/mm2 to 2.2 ± 0.29 N/mm2) and an increase in surface roughness (from 1.6 ± 0.32 Ra to 1.93 ± 0.28 Ra and from 0.58 ± 0.12 Ra to 0.68 ± 0.13 Ra for the internal and external surface roughness, respectively) after 2 weeks of dental bleaching. Results showed that Invisalign can be used for dental bleaching without excessive distortion or degradation of the aligner material. However, future clinical trials are required to further assess the feasibility of using Invisalign for dental bleaching.

Morphological, chemical and antimicrobial analysis of glass ionomer cements used for ART in posterior primary teethGlass ionomer cements (GICs) have been gaining prominence as material for atraumatic restorative treatment (ART) due to their acceptable ph

Glass ionomer cements (GICs) have been gaining prominence as material for atraumatic restorative treatment (ART) due to their acceptable physicochemical and biological properties. Objective: To analyze the surface morphology, chemical constitution, and antimicrobial action of GICs used for ART in posterior primary teeth. Material and methods: The tested materials were Vitro Molar®, Ketac Cem Easymix® and Riva Self Cure®. For the structural and chemical analysis, polyethylene tubes with an internal diameter of 3 mm and 3 mm in length were prepared, filled, and then transferred to a chamber with 95% relative humidity and a temperature of 37oC. The surface morphology of the tested materials was examined by scanning electron microscopy (SEM) and main components were investigated by energy-dispersive X-ray microanalysis. For the antimicrobial efficacy analyses, strains of Streptococcus mutans (ATCC 27853) were used. Petri dishes with brain heart infusion agar (BHIA) were inoculated with the microbial suspensions and three cavities were made in each agar plate and filled with one of the GICs. The plates were pre-incubated for 1 hour at room temperature and then incubated at 37oC for 24 to 48 hours. The inhibition zone around each well was recorded in mm. Results: SEM revealed irregular and rough external surface. Cracking was not observed. The main constituents were found to be aluminum, silicon, sodium, and fluoride. Barium was only observed in Vitro Molar®, while lanthanum was only observed in Ketac Cem Easymix®. Elemental mapping of the outer surface revealed high concentration of aluminum and silicon. Inhibition halos were only observed in Riva Self Cure®. Conclusion: The GICs presented irregular outer surfaces and similar chemical elements. Only Riva Self Cure® showed antibacterial action against the S. mutans.

Investigation of surface roughness post-processing of additively manufactured nickel-based superalloy Hastelloy X using electropolishing

A major problem of additively manufactured parts using laser powder bed fusion (LPBF) is the as-built high surface roughness. The poor surface finishing is detrimental to the mechanical and electrochemical properties of the parts. In this work, we present systematic investigations on surface roughness reduction of LPBF produced nickel-based superalloy Hastelloy X (HX) using electropolishing. The electrolyte used in this study is an environmentally safe deep eutectic solvent (DES) comprising a eutectic mixture of choline chloride and ethylene glycol in a 1:2 M ratio, respectively. Two different groups of LPBF HX parts separated for the purpose of electropolishing the external and internal surface were prepared. The results show that both the external and internal surface roughness can be effectively reduced using electropolishing in DES. For the parts with the external surface electropolished for 5 min, a surface roughness reduction down to 1.2 μm (Ra) with a bright and reflective surface appearance was achieved. This is a significant improvement in comparison to the high as-built surface roughness of 10.3 μm (Ra) with a dull and non-reflective surface appearance. For the internal surface electropolishing, the surface quality of a 3 mm diameter internal channel in an angled LPBF HX cylindrical tube was successfully enhanced. The DES electropolishing efficiency on LPBF HX was investigated using weight reduction as a function of the electropolishing time, and the microstructure of the electropolished LPBF HX was studied. A further improvement of the electrochemical properties for the electropolished surface was revealed by anodic polarization tests and electrochemical impedance tests. The electropolished surface was also revealed to be more hydrophobic than the as-built surface by water contact angle tests, which is beneficial to the corrosion resistance. The findings herein demonstrate the surface quality of the LPBF produced HX can be effectively improved using electropolishing, and also showed the feasibility of using DES as a promising alternative electrolyte to the conventional hazardous acid mixtures.

Numerical Study of Transient Elastohydrodynamic Lubrication Subjected to Sinusoidal Dynamic Loads for Rough Contact Surfaces

Abstract The purpose of this paper is to study the behaviour of transient elastohydrodynamic contacts subjected to forced harmonic vibrations, including the effect of surface waviness for concentrated counterformal point contact under isothermal conditions. Profiles of pressure and film thickness are studied to reveal the combined effects of sinusoidal external load and surface roughness on the lubrication problem. The time-dependent Reynolds’ equation is solved using Newton–Raphson technique. The film thickness and pressure distribution are obtained at different snap shots of time by simultaneous solution of the Reynolds’ equation and film thickness equation including elastic deformation and surface waviness. It is concluded that the coupling effects of the transient sinusoidal external load and wavy surface would result in increase in modulations of the pressure and film thickness profile in comparison to the case where the smooth contact surfaces are subjected to sinusoidal external load.

Droplet-based millifluidic technique for encapsulation of cinnamon essential oil: Optimization of the process and physicochemical characterization

The “millifluidic” technique could be considered as a novel approach for encapsulation of bioactive compounds and has a promising perspective in the field of food engineering or pharmaceutical science. In this study, we aim to optimize the encapsulation of cinnamon essential oil (CEO) by droplet-based millifluidic technique with four responses: encapsulation efficiency (EE), loading capacity (LC), sphericity factor (SF) and size of calcium-alginate millicapsules. The effects of alginate concentration (20–30 g/L), flow rate of alginate (1–1.6 mL/min), and flow rate of CEO (0.6–0.8 mL/min) were considered by a Box-Behnken design. The best concentration of chitosan as a coating layer on the optimized samples was selected based on the Young modulus of millicapsules. The regression models showed the significant effect (p < 0.05) of the three variables on the characteristics of millicapsules. The optimal millicapsules with 3.58 ± 0.23 mm diameter and 0.96 ± 0.01 S F showed 98.96 ± 1.2% and 70.14 ± 1.8% EE and LC, respectively. SEM images exhibited a rough external surface which changed to a rigid and smooth surface through the chitosan coating. The results of DSC and FTIR tests demonstrated the CEO entrapment in the millicapsules without any chemical interaction with the encapsulant materials. The disarray of crystallinity structure in XRD patterns revealed the successful encapsulation of CEO in the millicapsules. The non-Fickian case II in the mouth and small intestine and anomalous transport in the stomach were the main release mechanisms in the coated millicapsules. The release profile of CEO also fitted well with Ritger-Peppas model.

Fatigue life analysis of aero-engine blades for abrasive belt grinding considering residual stress

Abrasive belt grinding technology is widely used in the processing of aero-engine blades. Residual stress is used as an indicator of grinding gauge integrity, which has a significant impact on the fatigue performance of aero-engine blades. In fatigue life research, experiments are mainly used to explore the influence of residual stress on fatigue life. Restricted by factors such as experimental efficiency and cost, it is necessary to simulate the influence of residual stress in the process of fatigue failure. Based on the theory of crack initiation and propagation, this paper proposes a life prediction algorithm considering residual stress; carries out a bending vibration fatigue experiment and simulation fatigue life analysis of aero-engine blade grinding with abrasive belt; compares the results of experiments and simulations and proposes a residual stress equivalent calibration method. Used theory, simulation, and experiment to verify the effectiveness of the method, and uses this equivalent calibration method to analyze the effect of residual stress on the fatigue life of aero-engine blades ground by abrasive belts. The experimental results show that the surface residual compressive stress will optimize the size and distribution of the surface stress during the service process of the aero-engine blade. Under the same external load and surface roughness conditions, a larger surface residual compressive stress will increase the aero-engine blade stiffness, reduce the aero-engine blade’s vibration amplitude, and reduce Surface stress, which in turn, has a beneficial effect on fatigue life. The proposed calibration method considering residual stress can accurately predict the fatigue life of aero-engine blades with a prediction accuracy up to 90%.

Microstructure and Pressure-Driven Electrodeposition Stability in Solid-State Batteries

Interfacial deposition stability at the Li-metal-solid electrolyte interface in all solid-state batteries is governed by the stress-transport-electrochemistry coupling in conjunction with the polycrystalline/amorphous solid electrolyte architecture. In this work, we delineate the optimal solid electrolyte microstructure comprising grains, grain boundaries, and voids possessing desirable ionic conductivity and elastic modulus for superior transport and strength. An analytical formalism is provided to discern the impact of external “stack” pressure-induced mechanical stress on electrodeposition stability; the stress magnitudes obtained are in the megapascal range, considerably diminishing the stress-kinetics effects. For experimental stack pressures ranging up to 10 MPa, the impact of stress on reaction kinetics is negligibly small, and electrolyte transport overpotentials dictate electrodeposition stability. High current density operation with stable deposition can be ensured with ample external pressure, high temperature, and low surface roughness operation for a low shear modulus ratio of the solid electrolyte to Li-metal. Solid electrolyte architecture is screened via virtual generation and characterization Large grain size, low void size, and porosity provide favorable conduction and stiffness Stack pressure <10 MPa has negligible impact on stress-kinetics coupling High operating pressure, temperature, and low roughness can aid stable deposition Lithium electrodeposition is dependent on solid electrolyte microstructure, stack pressure, and operating temperature. Verma et al. suggest a method to delineate the architecture and operating conditions that lead to stable deposition.

Lubrication reliability analysis of spur gear systems based on random dynamics

An approach for lubrication reliability analysis of spur gear systems considering the randomness of external load and surface roughness is presented. The instantaneous failure probability of gear lubrication is captured by a gear stochastic dynamics model and a reliability model of elastohydrodynamic lubrication (EHL). The stochastic dynamics model is adopted to obtain the numerical characteristics of meshing force. The reliability model is established based on a mixed EHL line contact film thickness formula. The first-order second-moment method is employed for predicting failure probability of lubrication. The lubrication reliability of a gear pair excited by different intensity random load is studied. The results show that the lubrication failure probability in dedendum and single meshing region are higher than addendum.

Internal surface roughness enhancement of parts made by laser powder-bed fusion additive manufacturing

In this work, innovative electrochemical methods have been utilized to minimize the internal surface roughness of Inconel 625 laser powder-bed fusion (LPBF) additively manufactured (AM) parts with variable geometries as the performance of many parts depend on it. Initially, the effect of electropolishing time on external surface roughness and thickness loss was investigated. Subsequently, electropolished internal structures were studied and the results showed an average of 80% improvement in roughness. The quick and effective surface enhancement methodology proposed in this research can be applied to improve the performance of AM parts with functional internal and external surfaces.

Scelidosaurus harrisoniifrom the Early Jurassic of Dorset, England: the dermal skeleton

<i>Scelidosaurus harrisonii</i>from the Early Jurassic of Dorset, England: the dermal skeleton

Characterization of Lignocellulosic Biomass from Malaysian’s Yankee Pineapple AC6 Toward Composite Application

ABSTRACT The aim of this paper is to study the properties of the newly Malaysian pineapple variety, namely, Yankee pineapple’s leaf fibers (PALF) biofillers in composite applications. The fibers were extracted from the leaves, which were currently being thrown away or burned down. Comprehensive characterization of Yankee’s PALF was carried out to determine its chemical composition, surface morphology, and mechanical, crystallinity, and thermal properties. The results showed that the fiber had a high thermal degradation of 340°C (34% yield). On top of that, the fiber surface elemental composition captures carbon (53.56%) which had the highest atomic percentage followed by oxygen (42.93%) and potassium (3.51%). In addition, the fiber had a rough external surface observed through atomic force microscope analysis, resulting in good compatibility with the matrix polymer. The crystal index of fiber and its size give 55.22% and 2.17-nm values, respectively. Furthermore, 40 mm gauge length of single fiber had the highest tensile strength, which is 420.3 MPa compared to other values of the gauge length.

Evaluation of External Surface Structure, Roughness, and Absolute Depth Profile of Fluorotic Enamel Compared to Healthy Enamel Using Atomic Force Microscope: An In Vitro Study.

ABSTRACTFlouride has been previously shown to alter the morphology of hydroxyapatite crystals at various levels leading to altered enamel surface.AimTo characterize the external surface, roughness, and abs.How to cite this articleReddy NV, Vengala D, Snehika G, et al. Evaluation of External Surface Structure, Roughness, and Absolute Depth Profile of Fluorotic Enamel Compared to Healthy Enamel Using Atomic Force Microscope: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(3):246–250.

Microcapsule-based self-healing materials: Healing efficiency and toughness reduction vs. capsule size

We report the synthesis of controlled sized Urea-Formaldehyde (UF) microcapsules containing an epoxy healing agent via in situ emulsification polymerization for the study of self-healing epoxy systems. Scanning Electron Microscopy (SEM) confirmed that the capsules possessed rough external surface which enhanced mechanical interlocking. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy were employed so as to determine the capsules thermal stability and decompositions and encapsulated healing agent percentage. To our knowledge it is the first time the solid-state NMR is used for the estimation of encapsulated healing agent. The obtained results clearly indicated that with decreasing capsule size, capsules remained thermally stable at high temperatures (approximetly up to 230 °C). Additionally, capsule size is for the first time directly correlated to both healing efficiency and the reduction of mechanical performance after self-healing system incorporation. Healing efficiency is proportional to capsule size with larger capsules resulting in 68% maximum load recovery. However, smaller capsules result to lower reduction of properties, i.e. 7% as oppose to 18% for larger ones. Although healing efficiency can be enhanced through the use of relatively large capsules, this is in expense of mechanical performance, i.e. there is an optimal capsule size.

Reducing the roughness of internal surface of an additive manufacturing produced 316 steel component by chempolishing and electropolishing

Surface roughness of an as produced AM component is very high, which prohibits the direct utilization of additively manufactured (AM) components for the intended applications. Reducing surface roughness is exponentially more challenging for the internal surfaces of an AM component. This paper reports our research in the area of postprocessing of interior surfaces of an AM component. We have investigated electropolishing and chemical polishing (chempolishing) methods to reduce the surface roughness of the internal surface. We found that chempolishing was effective in simultaneously reducing the internal and external surface roughness of 316 steel AM components. Chempolishing is found suitable for any complicated AM shape and geometry. Our electropolishing methodology was effective in reducing the surface roughness of the internal or external surfaces provided that a counter electrode could be positioned in the proximity of the surface to be polished. We have performed optical profilometry, scanning electron microscopy, and contact angle measurement study to investigate the difference between electropolishing and chemical polishing methods.

New microcapsules based on isosorbide for cosmetotextile: Preparation and characterization

The preparation of polyurethane bio-based microcapsules containing the neroline fragrance aimed at cosmetotextile applications was investigated. The polyurethane shell material was synthesized by interfacial polycondensation using isosorbide and hexane diisocyanate as monomers.Chemical characterization by means of IR-ATR and TGA confirmed the formation of a polyurethane wall and the fragrance encapsulation up to 73% of the dry microcapsules. The physicochemical characterization of neroline-loaded microcapsules was carried out, including thermal properties, size distribution, morphology and zeta potential. The spherical microcapsules of size ranging between 2 μm and 100 μm had a rough external surface. Their thermal stability up to 260 °C was favorable regarding their application to deposition onto textile fibers. According to their IsoElectrical Point of 5.38, these microparticles were anionic at neutral pH. An isosorbide-based cationic surfactant has been adsorbed at the surface of the microcapsules for charge reversal into cationic and stronger binding to negatively charged cotton fabric.Besides, neroline-loaded microcapsules were fixed on pure cotton fabric by an impregnation technique. The reality and durability of the textile treatment were assessed by SEM and Gas Chromatography analysis. The cotton knitted fabric treated with fragrant microcapsules progressively released its microcapsule content; significant amount of residual neroline remained until 40 washing cycles.

Mixed matrix membranes incorporated with three-dimensionally ordered mesopore imprinted (3DOm-i) zeolite

Abstract MFI and LTA zeolites were synthesized inside three-dimensionally ordered mesoporous (3DOm) carbon. After the removal of the carbon, a highly crystalline 3DOm-imprinted zeolite with tunable and ordered mesopores was obtained. The nominal mesopore size can be finely controlled from 5 to 15 nm by changing the cage size of the 3DOm carbon. Under different synthesis conditions, the crystal size of the 3DOm-imprinted (3DOm-i) MFI was tuned from approximately 100 nm to several micrometers. The 3DOm-i zeolite was mesoporous and exhibited a spherical shape with a rough external surface. With the synthesis of 3DOm-i zeolites, mixed matrix membranes (MMMs) were prepared by incorporating them into a commercial polyimide matrix (i.e., Matrimid® 5218). Both MFI- and LTA-containing MMMs exhibited good adhesion between the zeolites and polymer because of their imprinted mesopore structure and rough external surface. Also, both MMMs exhibited a substantial increase in permeability to all the gas penetrants used in this work (except for NF3), resulting in an excellent N2/NF3 separation efficiency.

Electrolytic Plasma Surface Polishing of Complex Components Produced by Selective Laser Melting

The applicability of electrolytic plasma surface polishing to complex components produced by selective laser melting (SLM) is analyzed. By electrolytic plasma polishing by electrolyte spraying, the surface quality of components produced by SLM may be improved. This technology is found to decrease the surface roughness from Ra = 5.6 μm to 1.4 μm. The optimal pressure of the electrolyte jet is 0.02–0.05 MPa. At high pressures, the process becomes unstable. By electrolytic plasma polishing on the basis of electrolyte jets, uniform external and internal surface roughness of components produced by SLM may be ensured.

Test and numerical simulation of large angle wedge type of anchorage using transverse enhanced CFRP tendons for beam string structure

Carbon Fiber Reinforced Polymer (CFRP) has many superior material properties and can be used as prestressing tendons for prestressing structures instead of steel. A large angle wedge type of anchorage using transverse enhanced CFRP tendons is designed and tested for beam string structure. The results of laboratory tests and numerical analysis under static loading conditions of the prototype of anchorage are discussed. For a wedge with an angle of 10°, the 5-mm-diameter CFRP tendon was anchored successfully, but 7-mm- and 9-mm-diameter were not due to high pressure. The results of test revealed that the sleeve should ensure adequate roughness of internal and external surface, enough wall thickness and cutting width, and appropriate length to avoid some failure mode caused by components themselves. Based on the failure mode analysis of laboratory tests and numerical results, some details were suggested to improve the large angle wedge type of anchorage for applying to large diameter CFRP tendon.