Laser Scanning Microscopy Research Articles

Remineralization effects of enamel binding peptide, WGNYAYK, on enamel subsurface demineralization in vitro

Objectives: We investigated remineralization effects of enamel binding peptide (EBP), WGNYAYK, on enamel subsurface demineralization in vitro.Methods: Bovine lower incisor crowns were used as subsurface enamel demineralization samples, and changes of EBP binding, remineraliztion rate, hardness and microstructure were investigated. Binding of EBP, remineralization rate, hardness and structural changes were investigated. Fluorescein isothiocyatate (FITC)-labeled EBPs (0.4 mM, 4.0 mM, and 7.0 mM) were applied to the samples for 30 min at 37 °C, with sample surfaces and cross-sections observed by confocal laser scanning microscope (CLSM). Mineralization analysis samples were divided into 4 experimental groups; distilled water (DW), EBP 0.4 mM, EBP 4.0 mM, and EBP 7.0 mM. Mineral density changes were measured by micro-CT with hardness measured by nano-indentation. Samples were also observed by scanning electron microscope (SEM) for surface and longitudinal microstructure. ResultsCLSM images indicated that increased fluorescence was observed in the surface layer and up to about 20 μm below the surface layer. The remineralization rate was significantly higher for EBP 7.0 mM compared to DW (p = 0.008). Enamel surface hardness was significantly higher in all EBP groups compared to DW (p < 0.05) and was highest in the 7.0 mM group. SEM images showed obscuring of the superficial columnar structure in the 7.0 mM EBP group, indicating subsurface crystalline structure recovery. ConclusionThe results of this study suggest that EBP binds to demineralized enamel and promotes remineralization.

Semi-spontaneous temporal evolution of relief/fluorescence hybrid gratings for holographic encryption.

Holographic systems can reconstruct the entire wavefront of light which are developed as an excellent platform of information encryption. Although holography has utilized multiple modulation dimensions, little attention is given to its combination with fluorescence emitting. Herein, we propose a semi-spontaneous time-dependent encryption strategy of hybrid holographic fringes with surface relief and fluorescent emission mediated by a plasmonic polymer doped with fluorescent dyes. It is found that the two kinds of optical characteristic regions exhibit unique temporal evolution from the overlapped mode to the staggered one. The mode switching is closely related to the strong quenching effect of gold ions and nanoparticles which are dominant at the early and later recording stages, respectively. Thus, the real and deceptive information are recorded at different holographic writing periods. High-secret information of texts or images is constructed by the array of different sets of holographic fringes and is identified by comparing the dual-channel results of confocal laser scanning microscopes. This work puts a bright way to dynamic holographic encryption.

Gel properties and in vitro digestion of sea bass (Lateolabrax japonicus) myofibrillar protein – Lipid composite gels: Focus on lipid type and content

The effects of lipid type and content on gel and digestion properties of myofibrillar proteins (MPs) were studied. The MPs sol was combined with three types of lipid (peanut oil, sunflower oil, and lard) with different contents (0.5–2%) to obtain composite gels. As for whiteness, no differ was observed in composite gels without or with lipid addition. The water holding capacity and hardness of composite gels with lipid addition increased. Moreover, fourier transform infrared spectra (FTIR) demonstrated composite gels with 1% emulsion addition exhibited the highest β-sheet content. The confocal laser scanning microscope (CLSM) revealed that networks of composite gels with 1% emulsion addition possessed more densely compared to control group. During the in vitro digestion, high performance liquid chromatography (HPLC) results showed the peptide (>10 kDa) contents of composite gels with lipid addition were lower than that of control group under the simulated gastric phase. Moreover, the 2–5 kDa polypeptide content of composite gels with lipid addition was higher than that in observed in control group under intestinal phase. The results illustrated the gel and in vitro digestion mechanism of composite gels with lipid addition, which can be valuable for the fabrication of functional surimi products.

Characterization of Root and Foliar-Applied Iron Oxide Nanoparticles (α-Fe2O3, γ-Fe2O3, Fe3O4, and Bulk Fe3O4) in Improving Maize (Zea mays L.) Performance

Iron (Fe) oxide nanoparticles (NPs) improve crop growth. However, the comparative effect of root and foliar-applied different sources of Fe oxide NPs on plant performance at morphological and physiological levels still needs to be discovered. In this study, we characterized the growth and physiological responses of hydroponic-cultured maize seedlings to four sources of Fe (i.e., α-Fe2O3, γ-Fe2O3, Fe3O4 NPs, and bulk Fe3O4) and two application methods (root vs. foliar). Results showed that Fe concentration in root and shoot increased by elevating the level of NPs from 100 mg L−1 to 500 mg L−1. Overall, the responses of maize seedlings to different sources of Fe oxide NPs were as follows: Fe3O4 &gt; γ-Fe2O3 &gt; α-Fe2O3 &gt; bulk Fe3O4. The application of Fe at concentrations ranging from 100 mg L−1 to 500 mg L−1 had no significant effects on various growth parameters of maize, including biomass, chlorophyll content, and root length. Iron oxide NPs increased the plant biomass by 23–37% by root application, whereas it was 5–9% by foliar application. Chlorophyll contents were increased by 29–34% and 18–22% by foliar and root applications, respectively. The non-significant response of reactive oxygen species (i.e., superoxide dismutase, catalase, and peroxidase) suggested optimum maize performance for supplementing Fe oxide NPs. A confocal laser scanning microscope suggested that Fe oxide NPs entered through the epidermis and from the cortex to the endodermis. Our results provide a scientific basis that the root application of Fe3O4 at the rate of 100 mg L−1 is a promising approach to obtain higher maize performance and reduce the quantity of fertilizer used in agriculture to minimize environmental effects while improving crop productivity and quality. These findings demonstrated the tremendous potential of Fe NPs as an environmentally friendly and sustainable crop approach.

An innovative Pickering W/O/W nanoemulsion co-encapsulating hydrophilic lysozyme and hydrophobic Perilla leaf oil for extending shelf life of fish products

A Pickering water-in-oil-in-water nanoemulsion co-encapsulating lysozyme (LYS) and Perilla leaf oil (PO) was prepared using whey protein isolate-tannin acid conjugated nanoparticles (WPI-TA NPs) as emulsifiers, called LYS-PO-NE, and subsequently analyzed. The nano size and multiple phases was confirmed based on the results of confocal laser scanning microscope, scanning electron microscope, and droplet size analysis. LYS-PO-NE had high encapsulation efficiencies of 89.36 % (PO) and 43.91 % (LYS) and both could be released at a slow and continuous rate. The PO addition increased the droplet size, and the LYS addition delayed the release of PO. LYS-PO-NE also showed good storage, pH, thermal, and salt stability, and an effective combined bactericidal activity of LYS and PO against spoilage bacteria. Furthermore, the results of chilled salmon storage experiments indicated that LYS-PO-NE could extend the shelf life of chilled salmon to at least 6 days, demonstrating the potential in the shelf life for fish products.

Ultrastable High Internal Phase Pickering Emulsions: Forming Mechanism, Processability, and Application in 3D Printing.

High internal phase Pickering emulsions (HIPPEs) are versatile platforms for various applications owing to their low-density, solid-like structure, and large specific surface area. Here, naturally occurring polysaccharide-protein hybrid nanoparticles (PPH NPs) were used to stabilize HIPPEs with an internal phase fraction of 80% at a PPH NP concentration of 1.5%. The obtained HIPPEs displayed a gel-like behavior with excellent stability against centrifugation (10000g, 10 min), temperature (4-121 °C), pH (1.0-11.0), and ionic strength (0-500 mM). Confocal laser scanning microscope and cryo-scanning electron microscopy results showed that PPH NPs contributed to the stability of HIPPEs by effectively adsorbing and anchoring on the surface of the emulsion droplets layer by layer to form a dense 3D network barrier to inhibit droplet coalescence. The rheological analysis showed that the HIPPEs possessed a higher viscosity and lower frequency dependence with increasing PPH NP concentration, suggesting the potential application of such HIPPEs in three-dimensional (3D) printing, which was subsequently confirmed by a 3D printing experiment. This work provides highly stable and processable HIPPEs, which can be developed as facile and reusable materials for numerous applications. They can also be directly used for future food manufacturing, drug and nutrient delivery, and tissue reconstruction.

Antimicrobial efficacy of sodium hypochlorite and hyper-pure chlorine dioxide in the depth of dentin tubules in vitro

ObjectivesThe study aimed to compare the antibacterial effect of a novel disinfectant, hyper-pure chlorine dioxide (hClO2) to sodium hypochlorite (NaOCl) in various depths of dentin tubules.Materials and methodsThe distal root of the extracted lower molars was infected artificially with Enterococcus faecalis. The control group was rinsed with saline, and the test groups were irrigated with either 5% NaOCl or 0.12% hClO2. The longitudinally split teeth were stained by viability stain. The coronal third of the root was scanned with a confocal laser scanning microscope. The fluorescent intensities were measured, and the percentage of dead bacteria was calculated at depths up to 950 μm along the dentin tubules. The effect of penetration depth, irrigants, and their interaction on antimicrobial efficacy was determined by the linear mixed model.ResultsThe percentage of dead bacteria was higher both in the NaOCl (45.1 ± 2.3%, p < 0.01) and in the hClO2 (44.6 ± 3.8%, p < 0.01) irrigant groups compared to saline (23 ± 4.5%); however, there was no difference between them. The percentage of killed bacteria was not correlated with the depths in any group (p = 0.633).ConclusionsOur results suggest that the functional penetration depth of NaOCl is at least 2–3 times more than published to date. There is no difference in disinfection effectiveness along the dentin tubules between NaOCl and hClO2 until at least the measured 950 μm. However, both were only able to eradicate the intratubular bacteria partially.Clinical relevanceHyper-pure ClO2 could be used as an alternative or final adjuvant irrigant in endodontic treatment.

The Design and Optimization of Ceramide NP-Loaded Liposomes to Restore the Skin Barrier.

The impairment of skin integrity derived from derangement of the orthorhombic lateral organization is mainly caused by dysregulation of ceramide amounts in the skin barrier. Ceramides, fatty acids, and cholesterol-containing nano-based formulations have been used to impair the skin barrier. However, there is still a challenge to formulate novel formulations consisting of ceramides due to their chemical structure, poor aqueous solubility, and high molecular weight. In this study, the design and optimization of Ceramide 3 (CER-NP)-loaded liposomes are implemented based on response surface methodology (RSM). The optimum CER-NP-loaded liposome was selected based on its particle size (PS) and polydispersity index (PDI). The optimum CER-NP-loaded liposome was imagined by observing the encapsulation by using a confocal laser scanning microscope (CLSM) within fluorescently labeled CER-NP. The characteristic liquid crystalline phase and lipid chain conformation of CER-NP-loaded liposomes were determined using attenuated total reflectance infrared spectroscopy (ATR-IR). The CER-NP-loaded liposomes were imagined using a field emission scanning electron microscope (FE-SEM). Finally, the in vitro release of CER-NP from liposomes was examined using modified Franz Cells. The experimental and predicted results were well correlated. The CLSM images of optimized liposomes were conformable with the other studies, and the encapsulation efficiency of CER-NP was 93.84 ± 0.87%. ATR-IR analysis supported the characteristics of the CER-NP-loaded liposome. In addition, the lipid chain conformation shows similarity with skin barrier lipid organization. The release pattern of CER-NP liposomes was fitted with the Korsmeyer-Peppas model. The cytotoxicity studies carried out on HaCaT keratinocytes supported the idea that the liposomes for topical administration of CER-NP could be considered relatively safe. In conclusion, the optimized CER-NP-loaded liposomes could have the potential to restore the skin barrier function.

MDP-salts as an adhesion promoter with MDP-primers and self-adhesive resin cement for zirconia cementation

PurposeTo evaluate the effect of zirconia priming with MDP-Salt before MDP containing primers and self-adhesive cement on the shear bond strength.Materials and methodsFully sintered high translucent zirconia specimens (n = 120) were assigned into 2 groups (n = 60 each): Control (No Pretreatment) and Methacryloyloxydecyl dihydrogen phosphate salt (MDP-Salt) pretreated. Each group was divided into 3 subgroups (n = 20) according to cementation protocol: 1) MDP + Silane primer and conventional resin cement, 2) MDP+ Bisphenyl dimethacrylate (BPDM) primer and conventional resin cement, and 3) MDP containing self-adhesive resin cement. Shear bond strength (SBS) was measured after 10,000 thermocycling. Contact angle was measured for tested groups. Surface topography was assessed using a 3D confocal laser scanning microscope (CLSM). Weibull analysis was performed for SBS and one-way ANOVA for contact angle and surface topography measurements (α = 0.05).ResultsThe use of MDP-Salt significantly improved the SBS (p < .05) for all tested subgroups. Self-adhesive cement showed an insignificant difference with MDP + Silane group for both groups (p > .05). MDP + BPDM showed a significantly lower characteristic strength compared to self-adhesive resin cement when both were pretreated with MDP-Salt. No difference between all tested groups in the surface topographic measurements while MDP-Salt showed the highest contact angle.ConclusionMDP-Salt pretreatment can improve bonding performance between zirconia and MDP containing products.

Distribution of connexin 43 in the human pineal gland

BACKGROUND: Connexin 43 (Cx43) is one of the important gap junction proteins of astrocytes and is necessary for intercellular communication. To date, data on gap junctions in the human pineal gland are limited, and Cx43 has not been examined in this organ.&#x0D; AIM: This study aimed to investigate the distribution of gap junctions in the human pineal gland by simultaneous detection of Cx43 and the astrocyte marker glial fibrillary acidic protein (GFAP).&#x0D; METHODS: Fixed and paraffin-embedded samples of the human pineal gland (n=4) were used. The study participants were between 19 and 34 years old. For the simultaneous detection of Cx43 and GFAP in the human pineal gland, immunohistochemistry was used, followed by analysis using an LSM 800 confocal laser scanning microscope (Carl Zeiss, Germany).&#x0D; RESULTS: For the first time, our immunohistochemical study showed the presence of Cx43 in the human pineal gland. The confocal microscopy with double immunolabeling of Cx43 and GFAP visualized the individual clusters of Cx43-containing structures that were undistinguishable under transmitted light microscopy and showed the localization of the Cx43 on the membrane of astrocytes.&#x0D; CONCLUSION: The proposed method makes it possible to determine Cx43-positive structures in human pineal tissue, which are localized mostly in the area of astrocyte processes.

Effect of roasting and high-pressure homogenization on texture, rheology, and microstructure of walnut yogurt

The effect of roasting and high-pressure homogenization on the quality of yogurt made from peeled walnut kernels was explored in this study. The G' and G'' values of yogurt made from walnuts roasted at high temperatures were reduced. The water-holding capacity and hardness of walnut yogurt were reduced to 47.73% and 24.22 g, respectively. Increasing the homogenization pressure reduced the particle size of the walnut yogurt to 20.50 μm. Homogenized walnut milk at 150 MPa increased the viscosity, hardness, and consistency of yogurt product from 11.71 to 16.74 Pa.s, from 30.01 to 71.63 g and from 283.17 to 455.24 g·s, respectively. The confocal laser scanning microscope observation demonstrated a reduction in the size of fat and protein micelles in the homogenized yogurt samples, resulting in a compact structure. This study will contribute valuable scientific insights to the advancement of plant-based yogurt quality.

Self-cleaning foulant attachment on near-infrared responsive photocatalytic membrane for continuous dynamic removing antibiotics in sewage effluent environment

Bifunctional photocatalytic nanofiltration (PNF) membrane has become a reliable frontier technique for removing refractory organic micropollutants. However, the active mitigated fouling mechanism from the microscopic perspective during its long-term operation of purifying real micro-polluted water is rarely studied. Herein, with an integrated use of QSense Explorer and confocal laser scanning microscope techniques, self-cleaning foulant attachment on an activated and customized near-infrared responsive polymeric PNF (termed as nPNF) membrane with good service performance for continuous dynamic removing antibiotics in sewage effluent environment was firstly elucidated. Time-dependent changes in dissipation oscillation frequency, sensed mass and the visualized foulant spatial distribution all indicated that there were only sporadic foulant attachment, an extremely low fouling layer thickness and irreversible fouling rate on/of the activated nPNF membrane top surface, thereby endowing it with excellent self-cleaning characteristic. This is probably because the reactive oxygen species (mainly •O2− and •OH) concurrently destroys the integrity of fouling layer and its internal adhesion structure, transforming part of the irreversible fouling on nPNF membrane surface into reversible one that is easy to wash off. These new horizons provided useful insight on the fate of selected antibiotics in the to-be-removed stage and self-cleaning foulant attachment of PNF membrane.

BORS/BJR TRAVELLING FELLOWSHIP: A COMPARISON OF THE EFFECTS ON BONE TISSUE OF TWO ULTRASONIC CUTTING DEVICES OPERATING AT DIFFERENT FREQUENCIES

AbstractIntroductionUltrasonic cutting in surgery has great potential. However, a key limitation is heat created by friction between the bone and the blade. Bone has poor thermal conductivity which hinders the dissipation of heat, causing cell death near the cut site In addition, ultrasonic vibration may create microcracks. It was hypothesised that these effects on bone would vary with the frequency and displacement of the ultrasonically powered blade. Therefore varying frequencies and displacements of the tip of the blade were studied to find the combination with fewest microcracks and lowest temperature rise at the bone-tool interface.AimTo explore the effect of different frequencies and tip displacements of ultrasonic cutting devices on the amount of thermal and mechanical damage.MethodsIn vitro tests were conducted on fresh rat femoral shafts using two different frequencies; 20kHz and 35kHz.Two displacement amplitudes of two different frequencies were used: 23.9 μm (p-p) and 7.5 μm (p-p) both at 20kHz and 18.7 μm (p-p) and 27 μm (p-p) both at 35kHz and. Cooling was used to emulate clinical conditions. Histological examination (H &amp; E and TUNEL) was performed to identify live and dead cells. Further rat femoral shafts (n=6) were exposed to the same number of cuts by each tool to identify any micro-damage induced by different electrical currents using Micro-CT and confocal Laser scanning microscope. All experimental data were expressed as mean ± standard deviation. Statistical analysis was performed using one-way ANOVA, followed by Post Hoc multiple comparisons test. Differences between groups were considered statistically significant at p &lt; 0.05.ResultsThe cut site at 7.5 μm (p-p) in 20kHz displayed only indentation instead of a cut, and was excluded. Histological examination revealed a high incidence of cell death at the cutting edge, in both frequencies. At 35kHz and 27 μm (p-p) some charring was evident, while at 20kHz and 23.9 μm (p-p) more irregularities were seen on the surface of the cut indicating instability during cutting when this setting was used. In contrast, the 35kHz at 18.7 μm (p-p) resulted in a smoother cutting surface. The highest cell death percentage ranged from 25% (at 35kHz, 18.7 μm (p-p)) to 44 % (at 35kHz, 27 μm (p-p)). Most of the tool's effect was located within 25 µm of the cut surface. There was a significant decrease to &lt; 5 % at 200 µm. No cell death was found over 200 µm from the cut surface in both frequencies (35 kHz and 20 kHz). No significant difference in total percentage cell death was found between cutting at 35kHz and 18.7 μm (p-p) and at 20kHz and 23.9 μm (p-p). No microcracks were detected along the depth of the cut site at either frequency.ConclusionOf the 2 ultrasonic cutting frequencies tested, the combination of the higher vibration frequency (35kHz) and the lower displacement amplitude (18.7 μm (p-p) demonstrated least damage to the bone tissue. No microcracks were displayed when using either of the ultrasonic cutting frequencies.Declaration of Interest(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Reconstruction of Cardiac Images using the Confocal Laser Scanning Microscope

We suggested a cardioid aperture in the processing of cardiac images using the confocal laser scanning microscope (CSLM). We calculated the Point Spread Function (PSF) corresponding to the cardioid aperture and the cardiac images by using the FFT algorithm. Then, we studied the effect of the image rotation on the PSF. In addition, we computed the autocorrelation corresponding to the cardiac images and cardiac aperture and compared them with the autocorrelation of the uniform circular aperture. Also, we computed the cross-correlation of aligned and rotated cardiac images. Finally, we imaged the cardiac images using the confocal scanning microscope provided with the circular and cardioid shapes of apertures. The MATLAB code is used in the formation of all images and plots.

Egg white improved the quality of noodles with high mung bean content by protein aggregation behavior

AbstractBackground and ObjectivesMung bean, as a coarse grain, is rich in protein and phytochemicals. Noodles prepared from mung bean are nutritionally superior to traditional noodles. However, the absence of gluten protein in mung bean limits their incorporation level and might cause adverse effects on the quality of noodles. To address the quality degradation of noodles with high mung bean content due to the lack of gluten proteins, the effects of fresh egg white on their quality improvement were investigated. In this study, the dynamic rheological properties of the dough as well as the changes in free sulfhydryl and SS bonds were determined. The cooking characteristics, sensory, textural properties, and microstructure of the noodles were evaluated.FindingsResults revealed that the addition of 15% fresh egg white significantly improved the sensory scores of the wheat–mung bean (3:7) composite noodles, which might be attributed to the enhanced modulus of elasticity (G′) of the composite dough system, the increased hydrophilicity, and amount of free sulfhydryl and SS bonds in noodles. Meanwhile, scanning electron microscopy and confocal laser scanning microscopy further confirmed that the addition of 15% fresh egg white affected the structures of starch granule and protein network. Furthermore, the addition of 15% fresh egg white minimized the cooking loss and enhanced the springiness, adhesiveness, and chewiness of the noodles, which in turn resulted in the highest sensory scores.ConclusionsThe incorporation of 15% fresh egg white could enhance the quality characteristics of mung bean noodles by protein aggregation, thus receiving a favorable acceptance.Significance and NoveltyThis study explored the possibility of developing a novel noodle with 70% mung bean content. Moreover, the addition of 15% fresh egg white could significantly improve its quality and overall acceptability. This result contributes to the development of high‐content gluten‐free cereal or other legume noodles.

Microstructure characteristics and mechanical performances of the dissimilar welded joint of Q&P980 and Q&P1180 steels subjected to the paint-baking heat treatment

The dissimilar welded joints of Q&P980 and Q&P1180 steels with and without paint-baking heat treatment were investigated and their microstructures were characterized using confocal laser scanning microscope (CLSM), electron backscatter diffraction (EBSD), scanning electron microscope (SEM) and transmission electron microscope (TEM) in order to understand the change of mechanical performances of the welded joints. The two Q&P steels have slight differences in compositions, but the obviously varying fraction of tempered martensite and thus the difference in the tensile strength. Prior to paint-baking heat treatment, the dissimilar welds exhibit a lower martensite fraction of the intercritical heat-affected zone (ICHAZ) in the Q&P980 side compared to the Q&P1180 side, and it is not affected by the paint-baking treatment. After the treatment, the occurrence of carbides and the coarsening of martensite in the whole welded joint, as well as the decomposition of retained austenite in the ICHAZ, are observed. The paint-baking treatment also causes the decreasing microhardness values of all regions. Especially, the significantly decreasing microhardness in the fusion zone compared to other heat-affected zones results in a partial pull-out failure mode compared to a full pull-out failure mode without paint-baking treatment. The change in failure mode and the softening of the martensitic matrix are found to be responsible for the increase in the peak load and the energy absorption of the dissimilar welded joint of Q&P980 and Q&P1180 steels.

Ultrastructure of the lamprey head mesoderm reveals evolution of the vertebrate head

The cranial muscle is a critical component in the vertebrate head for a predatory lifestyle. However, its evolutionary origin and possible segmental nature during embryogenesis have been controversial. In jawed vertebrates, the presence of pre-otic segments similar to trunk somites has been claimed based on developmental observations. However, evaluating such arguments has been hampered by the paucity of research on jawless vertebrates. Here, we discovered different cellular arrangements in the head mesoderm in lamprey embryos (Lethenteron camtschaticum) using serial block-face scanning electron and laser scanning microscopies. These cell populations were morphologically and molecularly different from somites. Furthermore, genetic comparison among deuterostomes revealed that mesodermal gene expression domains were segregated antero-posteriorly in vertebrates, whereas such segregation was not recognized in invertebrate deuterostome embryos. These findings indicate that the vertebrate head mesoderm evolved from the anteroposterior repatterning of an ancient mesoderm and developmentally diversified before the split of jawless and jawed vertebrates.

Insights into the EPS production and distribution of planktonic and attached Sulfobacillus thermosulfidooxidans cells during bioleaching

Bacterial leaching can effectively promote the bioleaching of chalcopyrite by secreting extracellular polymeric substances (EPS). In this study, the production and distribution of EPS on the surface of planktonic and attached cells of Sulfobacillus thermosulfidooxidans (S. thermosulfidooxidans) during the process of chalcopyrite concentrate bioleaching were observed in situ using Field emission scanning electron microscope (FE-SEM) and Confocal laser scanning microscope (CLSM). The TOC content and key components of EPS were extracted during the chalcopyrite bioleaching process. Moreover, the main functional groups of extracellular polymorphs were identified through Fourier transmission-infrared spectroscopy (FT-IR). The results showed a similar trend in the evolution of EPS content in planktonic and attached cells. However, the EPS content secreted by the cells attached was more than that of planktonic cells during the entire process of bioleaching. Furthermore, the results of FE-SEM indicated that the EPS secreted by the attached cells is thicker and stickier, with better adsorption performance. The FT-IR spectrum analysis revealed that the O–H, C–H, and CO bonds are the main functional groups of EPS. This work further clarifies the role of EPS in the bioleaching process.

Evaluation of push-out bond strength, dentinal tubule penetration and adhesive pattern of bio-ceramic and epoxy resin-based root canal sealers.

Root canal sealing materials play a crucial role in an endodontic procedure by forming a bond between the dentinal walls and the gutta-percha. The current study aims to analyse the dentinal tubule penetration and adhesive pattern, including the push-out bond strength of six commercially available root canal sealers. Eighty-four mandibular first premolars were split into seven groups (and n = 12), Group 1: Dia-Root, Group 2: One-Fil, Group 3: BioRoot RCS, Group 4: AH Plus, Group 5: CeraSeal, Group 6: iRoot SP, Group 7: GP without sealer (control). Two groups were made, one for dentinal tubule penetration and the other for push-out bond strength; the total sample size was one hundred sixty-eight. Root canal treatment was performed using a method called the crown down technique, and for obturation, the single cone technique was used. A confocal laser scanning microscope (Leica, Microsystem Heidel GmbH, Version 2.00 build 0585, Germany) was used to evaluate dentinal tubule penetration, and Universal Testing Machine was utilised to measure the push-out bond strength (Shimadzu, Japan) using a plunger size of 0.4 mm and speed of 1mm/min. Finally, the adhesive pattern of the sealers was analysed by HIROX digital microscope (KH-7700). Statistical analysis was carried out by a one-way Anova test, Dunnet's T3 test, and Chi-square test. Highest dentinal tubule penetration was noticed with One-Fil (p<0.05), followed by iRoot SP, CeraSeal, AH Plus, Dia-Root also, the most negligible value was recorded for BioRoot RCS. Meanwhile, BioRoot RCS (p<0.05) demonstrated the greater value of mean push-out bond strength, followed by One-fil, iRoot SP, CeraSeal, AH Plus and Dia-Root. Regarding adhesive pattern, most of the samples were classified as type 3 and type 4 which implies greater sealing ability and better adherence to the dentinal wall. However, BioRoot RCS revealed the most type 4 (p<0.05), followed by AH Plus, One-Fil, CeraSeal and Dia-Root. The highest dentinal tubule penetration was shown by One-Fil compared to other groups. Meanwhile, BioRoot RCS had greater push-out bond strength and more adhesive pattern than other tested materials.

Influence of deposition voltage on tribological properties of W-WS2 coatings deposited by electrospark deposition

Electrospark deposition coatings were prepared with different deposition voltage on CrNi3MoVA steel substrates by using a W-WS2 sintered electrode and their tribological properties were investigated. The microhardness, roughness and tribological properties of the coatings were tested by using Vickers hardness tester, confocal laser scanning microscope and tribometer, and the morphologies, composition and phase structure were obtained by utilizing scanning electron microscopy (SEM), energy dispersive X-ray spectrum (EDS) and X-ray diffraction(XRD). The results showed that with the increase of deposition voltage, the hardness and roughness of the coatings increase. The coatings remarkably increase the tribological properties of CrNi3MoVA steel, and among the three coatings deposited at 40 V, 60 V and 80 V, the coating deposited at 60 V has the smallest friction coefficient and the best wear resistance.