Removal Of Layer Research Articles

Unity quantum yield of InP/ZnSe/ZnS quantum dots enabled by Zn halide-derived hybrid shelling approach

Environment-benign indium phosphide (InP) quantum dots (QDs) show great promise as visible emitters for next-generation display applications, where bright and narrow emissivity of QDs should be required toward high-efficiency, high-color reproducibility. The photoluminescence (PL) performance of InP QDs has been consistently, markedly improved, particularly owing to the exquisite synthetic control over core size homogeneity and core/shell heterostructural variation. To date, synthesis of most high-quality InP QDs has been implemented by using zinc (Zn) carboxylate as a shell precursor that unavoidably entails the formation of surface oxide on InP core. Herein, we demonstrate synthesis of superbly bright, color-pure green InP/ZnSe/ZnS QDs by exploring an innovative hybrid Zn shelling approach, where Zn halide (ZnX2, X = Cl, Br, I) and Zn oleate are co-used as shell precursors. In the hybrid Zn shelling process, the type of ZnX2 is found to affect the growth outcomes of ZnSe inner shell and consequent optical properties of the resulting heterostructured InP QDs. Enabled by not only the near-complete removal of the oxide layer on InP core surface through the hybrid Zn shelling process but the controlled growth rate of ZnSe inner shell, green InP/ZnSe/ZnS QDs achieve a record quantum yield (QY) up to unity along with a highly sharp linewidth of 32 nm upon growth of an optimal ZnSe shell thickness. This work affords an effective means to synthesize high-quality heterostructured InP QDs with superb emissive properties.

Evaluation of smear layer and Ca/P ratio in intra-radicular dentine irrigated with different irrigants adjunct with diode laser

BackgroundThis study aims to determine the smear layer removal from the root canals using different irrigant solutions with diode laser.MethodsA set of sixty human upper incisor teeth were chosen. Access cavity preparation was done followed by canal instrumentation. Samples were divided into six groups (Group A: sodium hypochlorite NaOCl, Group B: NaOCl + diode laser, group C: NaOCl + EDTA ethylene diamine tetra-acetic acid solution, Group D: NaOCl + EDTA + diode laser, Group E: NaOCl + garlic extract, Group F: NaOCl + garlic extract + diode laser. Examining the smear layer removal at the coronal, middle and apical thirds of the root canals was done by using electron microscope analysis. Using an energy-dispersive X-ray, the calcium/phosphorus Ca/P ratio was measured.ResultsAmong the examined groups, there were not any significant differences regarding the smear layer removal. The elimination of smear layers at the middle and coronal thirds was greater in all examined groups than in the apical third. EDX analysis revealed no statistically significant variation between the tested groups.ConclusionsUsing diode laser with sodium hypochlorite and ethylene diamine tetra-acetic acid irrigant solution was more effective for the elimination of smear layers. Garlic extract could be used as an alternative irrigant solution in debris removal.

Color-encoded multicompartmental hydrogel microspheres for multiplexed bioassays

We develop color-encoded multicompartmental hydrogel (MH) microspheres tailored for multiplexed bioassays using a drop-based microfluidic approach. Our method involves the creation of triple emulsion drops that feature thin sacrificial oil layers separating two prepolymer phases. This configuration leads to the formation of poly(ethylene glycol) (PEG) multi-compartmental core-shell microspheres through photopolymerization, followed by the removal of the thin oil layers. The core compartments stably incorporate pigments, ensuring their retention within the hydrogel network without leakage, which facilitates reliable color encoding across varying spatial positions. Additionally, we introduce small molecule fluorescent labeling into the chemically functionalized shell compartments, achieving consistent distribution of functional components without the core's contamination. Importantly, our integrated one-pot conjugation of these color-encoded microspheres with affinity peptides enables the highly sensitive and selective detection of influenza virus antigens using a fluorescence bioassay, resulting in an especially low detection limit of 0.18 nM and 0.66 nM for influenza virus H1N1 and H5N1 antigens, respectively. This approach not only highlights the potential of our microspheres in clinical diagnostics but also paves the way for their application in a wide range of multiplexed assays.

Assessment of Smear Layer Removal and Push-Out Bond Strength Efficacy of Traditional and Herbal Root Canal Irrigants Across Different Root Levels: An In Vitro Study.

Endodontic therapy requires meticulous root canal debridement, pathogen elimination, and effective obturation to prevent microbial intrusion. The presence of the smear layer hinders sealer penetration, compromising sealing effectiveness. Sodium hypochlorite and chlorhexidine are esteemed endodontic irrigants. Herbal extracts like neem and tulsi, with antimicrobial and anti-inflammatory properties, show promise for root canal irrigation. The study aimed to evaluate the efficacy of various irrigants in removing the smear layer and enhancing push-out bond strength at different root canal levels. One hundred mandibular premolars with single canals were collected, and 50 samples each were used for the smear layer and push-out bond strength analysis. Neem and tulsi extracts were prepared for irrigation. Teeth were decoronated, and up to 30 (6%) canals were prepared and were randomly divided into five groups based on irrigants used. A smear layer examination was conducted after longitudinally sectioning the tooth and sections were observed in a scanning electron microscope (SEM). Obturation was done in the remaining samples, and the push-out bond strength was assessed using a universal test machine. Sodium hypochlorite showed the highest smear layer removal efficacy followed by chlorhexidine, neem, tulsi leaves with rose water extract, and normal saline. Chlorhexidine exhibited the highest push-out bond strength, with the coronal third presenting the strongest values, followed by neem, tulsi with rose water, normal saline, and sodium hypochlorite. The study underscores the potential of herbal irrigants in endodontic therapy, indicating promising results while emphasizing the necessity for further clinical trials to validate their efficacy and other properties.

Unlocking the potential of supramolecular polymers with bimodal molecular weights for instant and strong underwater adhesion

Developing adhesives suitable for underwater environments remains a formidable challenge due to the barrier presented by water, hindering contact between the adhesive and adherend. In this work, supramolecular adhesives prepared by mixing low and high molecular weight poly(butyl acrylate)-based copolymers are manifested to function effectively for underwater adhesion regardless of substrates’ affinity to water. Optimization of adhesion performance is achieved by manipulating the copolymer composition, resulting in the remarkable adhesion strengths of 1290 N m-1 and 1047 N m-1 to hydrophobic PET and hydrophilic glass substrates, respectively. The observed high underwater adhesion is attributed to a synergistic effect: instant and efficient removal of the hydration layer facilitated by the low molecular weight polymer strands, and mechanical resilience conferred by the high molecular weight strands featured by chain entanglements. Adequate interfacial interactions are attained by the supramolecular interactions including cation-π and π-π bonding. Notably, owing to its inherent hydrophobicity, the adhesive can be stored underwater for over a week and still displays 842 N m-1 peel strength to glass substrate. This work unlocks the potential of supramolecular adhesives with bimodal molecular weight distribution for instant and strong underwater adhesion, providing a straightforward yet scalable strategy to produce high-performance underwater adhesives.

H+ implantation induced defects distribution in 4H-SiC single crystal film fabricated by Crystal-Ion-Slicing and its effects on electrical behavior: A multiple characterization study

The composite substrate of SiC single crystal films fabricated by Crystal-Ion-Slicing (CIS) is acknowledged as an excellent material platform for the realization of electronic devices with specific functions. In CIS technology, the transferred monocrystalline films can retain good monocrystalline quality close to the virgin monocrystalline quality, but the lattice damage caused by ion implantation and crystal cleavage is still not negligible. The distribution of H+ implantation induced defects is studied in this paper, according to which the transferred film can be divided into lattice distortion region, moderately damaged region and application region. The lattice distortion region has serious lattice defects and stacking faults, while the moderately damaged layer is dominated by high lattice stress and high density point defects. For application region, in addition to the defect morphology, its influence on the electrical behavior is also investigated, which indicate the defects are mainly vacancy defects introduced by the H+ penetration, which act as carrier traps and recombination centers in electronic behavior. The research work is helpful to further understand the microstructure and defect distribution of the films of various materials fabricated by the common technology CIS, and can provide a theoretical basis for further defect layer removal and defect repair.

Effect of methane flow in inverse diffusion flame and surface morphology on synthesis of copper–carbon nanotubes composite

ABSTRACT In an inverse diffusion flame of fuel-rich methane–air mixture, a distinct separation between a yellow flame situated atop a high-temperature blue flame structure enabled the growth of carbon nanotubes on relatively low melting temperature copper substrates within a carbon-rich precursor environment. However, high-affinity passivation layers formation on copper prevented the diffusion of carbon precursors, rendering the growth of carbon nanotubes on copper challenging. Removal of passivation layers via sulphuric acid treatment facilitates the synthesis of carbon nanotubes within the flame. Nevertheless, the impact of sulphuric acid treatment on the surface morphology of copper, and its influence on the growth of carbon nanotubes in the presence of methane–air mixtures, remains relatively unexplored. This research investigates the effects of sulphuric acid treatment and methane–air mixtures towards the growth of carbon nanotubes on copper substrates. Application of sulphuric acid treatment yields a surface characterised by high surface area-to-volume nano-hills morphology, which enhances the adsorption of carbon atoms and leads to the growth of carbon nanotubes with lifted copper nanoparticles. The optimal growth of carbon nanotubes occurs at a specific methane flow rate, where the supply of carbon precursors aligns with the diffusion of carbon atoms and growth rate of carbon nanotubes.

Effect of free liquid layer quantity on bacteria and protein adhesion to liquid infused polymers.

Liquid-infused polymers are recognized for their ability to repel foulants, making them promising for biomedical applications including catheter-associated urinary tract infections (CAUTIs). However, the impact of the quantity of free liquid layer covering the surface on protein and bacterial adhesion is not well understood. Here, we explore how the amount of free silicone liquid layer in infused silicone catheter materials influences the adhesion of bacteria and proteins relevant to CAUTIs. To alter the quantity of the free liquid layer, we either physically removed excess liquid from fully infused catheter materials or partially infused them. We then evaluated the impact on bacterial and host protein adhesion. Physical removal of the free liquid layer from the fully infused samples reduced the height of the liquid layer from 60 μm to below detection limits and silicone liquid loss into the environment by approximately 64% compared to controls, without significantly increasing the deposition of protein fibrinogen or the adhesion of the common uropathogen Enterococcus faecalis. Partially infused samples showed even greater reductions in liquid loss: samples infused to 70%-80% of their maximum capacity exhibited about an 85% decrease in liquid loss compared to fully infused controls. Notably, samples with more than 70% infusion did not show significant increases in fibrinogen or E. faecalis adhesion. These findings suggest that adjusting the levels of the free liquid layer in infused polymers can influence protein and bacterial adhesion on their surfaces. Moreover, removing the free liquid layer can effectively reduce liquid loss from these polymers while maintaining their functionality.

Relationship between the root processing method and quality of herbal medicine of Rauvolfia serpentina cultivated in Japan

Rauvolfia serpentina roots are used as herbal medicine for snake and insect bites, fever, malaria, abdominal pain, hypertension, and dysentery in Southeast Asian countries. This study evaluates the content of reserpine, ajmaline, and ajmalicine in R. serpentina roots obtained with an efficient root processing method. The plants were cultivated in Tanegashima Island in southern part of Japan, where NIBIOHN's experimental farm station is located. We examined both the type of cork layer removal method (manual work, drum mixer washing, and high-pressure washing) and dried roots. We found that the resulting active ingredient contents were not significantly different between manual work and 30 min of drum mixer washing, and high-pressure washing. The washing in a drum mixer for 30 min could be an efficient root processing method. The amount of each active ingredient was compared in each root part (large-, middle-, and small-diameter roots), and there were no significant difference in their contents. In conclusion, R. serpentina roots having a diameter ≥ 0.5 cm contain a similar amount of active ingredients, suggesting that the quality of the crude drug does not vary in the root part. Thus, our study provides significant insights into the use of R. serpentina roots for herbal medicine applications as well as constituents of active ingredients.

Effectiveness of EndoActivator, PATS Vario system, and XP-endo Finisher files on smear layer removal under scanning electron microscope: A comparative study.

The smear layer may harbor many bacteria; hence, alternative methods are used to disrupt and remove biofilm. The aim of the study was to compare the effectiveness of EndoActivator, PATS Vario System, and XP-endo Finisher files on smear layer removal using a scanning electron microscope. Sixty single-rooted extracted premolars with Vertucci Type 1 configuration were decoronated and divided into four groups. The groups were instrumented with the rotary ProTaper file system. All specimens were flushed with 1 ml of 3% sodium hypochlorite. Group 1 was irrigated with a conventional needle and syringe. In Group 2, the irrigant was activated with an EndoActivator. In Group 3, the irrigant was activated with PATS Vario system, and in Group 4, XP-endo Finisher files were used after biomechanical preparation to remove debris and smear layer. All specimens were finally rinsed with 3 ml of 3% sodium hypochlorite. The teeth underwent longitudinal splitting and grooving in the coronal, middle, and apical thirds, and then, the samples were taken for scanning electron microscopy to evaluate the amount of smear layer removal in each third. The middle and coronal thirds Showed that almost similar efficacy to remove smear layer in both Group II and Group III. At the apical third, Group III showed comparatively better results than Group I, II, and IV, respectively. Equal amount of smear layer was seen with EndoActivator and PATS Vario system when used as sonic irrigation devices.

Evaluation and comparison of the efficiency of ultrasonically activated intracanal irrigants grapeseed and pineapple extract in removing smear layer from the apical third of the root canal: An in vitro SEM analysis

ABSTRACT Aim: This study aims to evaluate and compare the efficiency of grapeseed and pineapple extract in removing smear layer from the apical third of root canal, with and without ultrasonic activation. Methods: Eighty single-rooted permanent teeth were divided into two main groups: Group I: conventional syringe irrigation and Group II: ultrasonic activation. Each group was subdivided into two experimental groups, i.e. grapeseed and pineapple extract and one control group, i.e., 17% ethylenediaminetetraacetic acid (EDTA). For each subgroup, instrumentation was done using ProTaper Gold up to size F3 and irrigated with 5 mL of the respective irrigant, followed by a final rinse of 2.5 mL of 5.25% NaOCl. For Group II, the respective irrigant was ultrasonically activated for 1 min, followed by a final rinse of 2.5 mL of 5.25% NaOCl. Smear layer evaluation was done with scanning electron microscope, and data were statistically analyzed. Results: In Group I, both pineapple and grapeseed extracts were more effective than 17% EDTA in removing smear layer from the apical root canal. However, in Group II, 17% EDTA showed highest efficacy in smear layer removal, followed by pineapple and grapeseed extracts (P < 0.05). Conclusion: Natural extracts such as pineapple and grapeseed seeds extracts exhibit potential for smear layer removal in the apical third, without the disadvantage of dentinal erosion from synthetic smear layer removing agents.

The Efficacy of Nano Magnesium Oxide and Nano Silver Fluoride on Canal Cleanliness and Smear Layer Removal (An In Vitro Study).

The Efficacy of Nano Magnesium Oxide and Nano Silver Fluoride on Canal Cleanliness and Smear Layer Removal (An In Vitro Study).

Chemical Modifications of Recycled Concrete Aggregate

The necessity for environmental sustainability has prompted the utilization of recycled concrete aggregates (RCA) sourced from structural demolition sites for the production of recycled aggregate concrete (RAC). The primary element impacting the quality of recycled concrete aggregate (RCA) is the mortar paste that adheres to the natural aggregate (NA). The cement mortar adhered to recycled concrete aggregate exhibits higher porosity and water absorption levels, along with reduced strength compared to natural aggregate. These characteristics negatively impact both the mechanical properties and durability of fresh and hardened concrete incorporating recycled concrete aggregate. As a result, it is crucial to enhance the interface by improving the surface of the aggregate or by removing the mortar adhered to the NA. Methods for achieving this include surface modification of the aggregate or removing adhered paste from the natural aggregate (NA). This research includes treatment involving acidic solutions particularly hydrochloric acid (HCl), and sulphuric acid (H2SO4), for mortar layer removal from RCA, analyzing their impact on the mechanical properties of aggregates and durability of concrete incorporating RCA.

Degradation Processes of Two Compound Layers on Nitrided Surfaces During the Wear Test by “Block on Hot Al Cylinder”

The results obtained in the study help to explain the degradation process of the nitrided steel compound layer. Compound layers with different properties on gas-nitrided H10 tool steel blocks were tested for wear with “block on hot Al cylinder”. Degradation processes were observed on both compound layers with different properties and at three contact pressures. In order to observe the degradation processes in the compound layers, the wear tests were interrupted at various fixed time intervals and the resulting changes were closely monitored. The comprehensive analysis highlighted the complexity of the degradation process in the compound layers and emphasized the existence of complex relationships between the above-mentioned parameters. The reaction of the nitrided steel surface with hot Al is more pronounced in areas with lower contact pressure, while adhesive removal and furrow formation are pronounced in areas with low and medium contact pressure. This process begins with a sufficient density of the areas where islands of adhesive removal are located, their enlargement during the test, the breaking up of the walls between them, and finally the removal of the compound layer in the sliding direction, which appears as furrowing in the final phase of wear.

Multi-Objective Optimization of Laser Cleaning Quality of Q390 Steel Rust Layer Based on Response Surface Methodology and NSGA-II Algorithm.

To improve the laser cleaning surface quality of rust layers in Q390 steel, a method of determining the optimal cleaning parameters is proposed that is based on response surface methodology and the second-generation non-dominated sorting genetic algorithm (NSGA-II). It involves constructing a mathematical model of the input variables (laser power, cleaning speed, scanning speed, and repetition frequency) and the objective values (surface oxygen content, rust layer removal rate, and surface roughness). The effects of the laser cleaning process parameters on the cleaning surface quality were analyzed in our study, and accordingly, NSGA-II was used to determine the optimal process parameters. The results indicate that the optimal process parameters are as follows: a laser power of 44.99 W, cleaning speed of 174.01 mm/min, scanning speed of 3852.03 mm/s, and repetition frequency of 116 kHz. With these parameters, the surface corrosion is effectively removed, revealing a distinct metal luster and meeting the standard for surface treatment before welding.

Polishing performance and material removal mechanism in the solid-phase Fenton reaction based polishing process of SiC wafer using diamond gel disc

The use of SiC wafer is widespread in many fields, especially in aerospace, energy, 5 G communications, and microelectronics. Chemical-mechanical polishing (CMP) is the primary method used for achieving an ultra-smooth surface on SiC wafers. However, CMP suffers from low efficiency, leading to increased processing time and costs. To address this issue, we developed a novel diamond gel polishing disc that incorporates SiO2/Fe3O4 (S/F) powder. The disc enhances polishing efficiency through a solid-phase Fenton reaction between the disc and SiC. The research investigates the reaction mechanism and the material removal model of the polishing process using SEM, TEM, and XPS analysis. Experimental studies are conducted to assess the polishing performance and validate the effectiveness of the theoretical model. The findings indicate that SiC undergo a solid-phase Fenton reaction with polishing disc mixed S/F powder (SG-S/F disc) during polishing. The Fenton reaction generates hydroxyl radicals (·OH), which break the Si-C and Si-Si bonds in the crystal structure, leading to the formation of a softer nanoscale amorphous oxide layer on the SiC surface. The cyclic generation and removal of this oxide layer enable highly efficient polishing of SiC wafers. Compared to a gel disc without S/F (SG disc), SiC polished with the SG-S/F disc exhibits superior surface quality. Additionally, the material removal rate (MRR) of the SG-S/F disc reaches 1.42 μm/h, representing a 51.1 % improvement over that of the SG disc. These results clearly demonstrate that the solid-phase Fenton reaction significantly enhances the polishing performance of the gel polishing disc.

Degradable and Printed Microstrip Line for Chipless Temperature and Humidity Sensing

AbstractResearch on chipless and passive architectures for environmental sensing is generating high interest because they do not require any semiconductor components or batteries to operate, thus resulting in an eco‐friendlier footprint. This study demonstrates a printed microstrip line with multiple resonators using biodegradable materials to continuously monitor temperature and relative humidity (RH). Constructed with a paper substrate and printed zinc conductive lines, and encapsulated with beeswax to protect against the interference of humidity, the microstrip line integrates spiral‐shaped resonators. One resonator operates at 1.2 GHz for temperature sensing, while another, coated with konjac glucomannan serves for relative humidity sensing at 2 GHz. The multi‐resonating features allow for a simultaneous assessment of temperature and humidity. The microstrip line displays a linear sensitivity to temperature of −1.35 MHz °C−1 and a non‐linear relative humidity sensitivity ranging between −0.8 and −8 MHz/%RH from 30% to 70% RH. Its degradation in a lab‐made compost for 70 days shows the removal of the transducing layer in 7 days and degradation of the cellulosic substrate starting after 5 weeks. The developed environmental sensing devices are notably promising for future applications in smart packaging and the tracking of goods aiming at the minimization of electronic waste.

Progressive Induction Hardening: Measurement and Alteration of Residual Stresses

Progressive induction hardening is an in-line steel heat treatment method commonly used to surface harden powertrain components. It produces a martensitic case layer with a sharp transition zone to the base material. This rapid process will induce large residual stresses, where a compressive state in the case layer will shift to a tensile state in the transition zone. For fatigue performance, it is important to quantify the magnitude and distribution of these stresses, and moreover how they depend on material and processing parameters. In this work, x-ray diffraction in combination with a layer removal method is used for efficient and robust quantification of the subsurface stress state, which combines electropolishing with either turning or milling. Characterization is done on C45E steel samples that were progressively induction hardened using either a fast or slow (27.5 or 5 mm/s, respectively) scanning speed. The results show that although the hardening procedures will meet arbitrary requirements on surface hardness, case depth and microstructure, the subsurface tensile stress peak magnitude is doubled when using a fast scanning speed. However, the near-surface compressive residual stresses are comparable. In addition, the subsurface tensile residual stress peak is compared with the on-surface tensile stresses in the fade-out zone.

Ti/Mg dissimilar joining by eutectic-melting-induced liquid metal dealloying

Ti and Mg alloys, which have thermodynamically immiscible main components, have been chemically joined in previous work using a third element with high affinity for both elements. However, this strategy is challenging in precisely controlling brittle intermetallic compounds formed at a joint interface. In this study, we mechanically joined pure Ti and pure Mg without brittle layers by forming bicontinuous microstructure, 3D entanglement of immiscible phases, at the joint interface. We butt-joined pure Mg and Ti–Cu alloy interlayer, which we pre-diffusion bonded to the pure Ti and heated at 813 K and 20 MPa for 5 min. At the joint interface, Cu and Mg eutectic melted, which induced liquid metal dealloying of the interlayer. The entire Ti–Cu interlayer is dealloyed, and a byproduct (Mg–Cu phase) is removed by pressurization during melting. These brittle layer removal processes left only α-Ti/Mg–Cu phase bicontinuous microstructure at the joint interface, improving the joint strength. Ti/Mg joints fractured at the Mg base metal at ca. 90 MPa by tensile tests. The findings of this study provide the basis for achieving immiscible alloy joining, for which effective joining methods have not yet been established.

DEVELOPMENT OF RECOVERY TECHNOLOGY OF CENTRIFUGAL PUMP IMPELLER IN PLASMA SPRAY DEVICE

Modern oil field pumps are widely used in drilling and operation of wells. Most of the pumps used in drilling oil wells are centrifugal pumps. Centrifugal pumps fail for many reasons after a long period of operation. One of the most important parts of these pumps is the impeller. Impeller failures lead to stoppages in centrifugal pumps. In order to prevent stoppages, it is necessary to increase longevity and extend the time between repairs, eliminate malfunctions in the impeller. The main causes of failure are vibration and cavitation, corrosion and wear in the pump. The article concerns the process of removing the layer by plasma spraying performed to increase the resistance to corrosion and wear of the centrifugal pump impeller. Chromium, nickel, tungsten and molybdenum scraps were used to obtain this layer. Keywords: Centrifugal pump, impeller, erosion, cavitation, plasma method, layer removal, stops.