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ACS Omega Dec 2022Cooperite (PtS) is one of the main sources of platinum in the world and has not been given much attention, in particular from the computational aspect. Besides, the...
Cooperite (PtS) is one of the main sources of platinum in the world and has not been given much attention, in particular from the computational aspect. Besides, the surface stability of cooperite is not fully understood, in particular the preferred surface cleavage. In the current study, we employed computer modeling methods within the plane-wave framework of density functional theory with dispersion correction and the parameter to correctly predict the bulk and surface properties. We reconstructed and calculated the geometries and surface energies of (001), (100), (101), (112), (110), (111), and (211) cooperite surfaces of stoichiometric planes. The Pt d-orbitals with = 4.5 eV and S p-orbitals with = 5.5 eV were found optimum to correctly predict a band gap of 1.408 eV for the bulk cooperite model, which agreed with an experimental value of 1.41 eV. The PtS-, Pt-, and S-terminated surfaces were investigated. The structural and electronic properties of the reconstructed surfaces were discussed in detail. We observed one major mechanism of relaxation of cooperite surface reconstructions that emerged from this study, which was the formation of Pt-Pt bonds. It emanated that the (110) and (111) cooperite surfaces underwent significant reconstruction in which the Pt cation relaxed into the surface, forming new Pt-Pt (Pt ) bonds. Similar behavior was perceived for (101) and (211) surfaces, where the Pt cation relaxed inward and sideways on the surface, forming new Pt-Pt (Pt ) bonds. The surface stability decreased in the order (101) > (100) ≈ (112) > (211) > (111) > (110) > (001), indicating that the (101) surface was the most stable, leading to an octahedron cooperite crystal morphology with truncated corners under equilibrium conditions. However, the electronic structures indicated that the chemical reactivity stability of the surfaces would be determined by band gaps. It was found that the (112) surface had a larger band gap than the other surfaces and thus was a chemical stability competitor to the (101) surface. In addition, it was established that the surfaces had different reactivities, which largely depended on the atomic coordination and charge state based on population atomic charges. This study has shown that cooperite has many planes/surface cleavages as determined by the computed crystal morphology, which is in agreement with experimental X-ray diffraction (XRD) pattern findings and the formation of irregular morphology shapes.
PubMed: 36506214
DOI: 10.1021/acsomega.2c02867 -
European Oral Research Sep 2022The objective of this experimental invitro study was to investigate the effects of resin infiltration (RI) on surface roughness, microhardness, color and surface...
PURPOSE
The objective of this experimental invitro study was to investigate the effects of resin infiltration (RI) on surface roughness, microhardness, color and surface characteristics of artificially demineralized root surfaces.
MATERIALS AND METHODS
Forty-two root specimens prepared from freshly extracted intact human upper incisors were subjected to surface roughness, microhardness, and color tests. Profilometer was used to measure surface roughness and Vicker's Hardness tester was used to measure the changes in microhardness. The color measurements were performed by a spectrophotometer using the CIELAB parameters. Following measurements, specimens were divided into 3 groups (n=14): G1: intact root surfaces, G2: demineralized root surfaces and G3: Resin infiltrated root surfaces (Icon, DMG) following demineralization. Surface roughness, microhardness and color measurements were repeated in G2 and G3 after demineralization and RI. One specimen from each group was examined by SEM. Data were analyzed statistically (p<0.05).
RESULTS
Application of RI to artificially demineralized root surfaces significantly decreased the surface roughness (p<0.001) and increased the microhardness (p=0.023). RI also affected the color of demineralized root surfaces. SEM examinations revealed that the porosities on demineralized root surfaces seemed to be sealed after RI.
CONCLUSION
RI affected the surface roughness, microhardness, color and surface appearance of artificially demineralized root surfaces.
PubMed: 36660219
DOI: 10.26650/eor.2022948009 -
Dental Research Journal 2024Polyetheretherketone (PEEK) has favorable properties that make it able to be used as a denture base material, but it is also susceptible to the adhesion of...
BACKGROUND
Polyetheretherketone (PEEK) has favorable properties that make it able to be used as a denture base material, but it is also susceptible to the adhesion of microorganisms. In this study, we applied Octafluoropentyl (meth) acrylate (OFPA) coating on the PEEK polymer surface by using plasma spray and investigated the functional groups present on the surface, changes in the surface energy and adhesion.
MATERIALS AND METHODS
In this experimental study, the samples were placed in a control group without surface preparation and three experimental groups that were subjected to plasma spray for 10, 30, and 60 s and then impregnated with degassed Octa fluoropentyl (meth) acrylate (Sigma-Aldrich, USA) monomer. Fourier transform infrared spectroscopy (FTIR) was used to identify the functional groups and new chemical bonds between PEEK and OFPA, and Sessile Drop Method was used to evaluate the surface's wettability. The surface morphology was checked using a LEXT OLS4000 (Olympus-Japan) microscope, and the inhibition of adhesion was also checked by counting the colonies in terms of colony forming unit/mL (CFU/mL). Kurskal-Wallis analysis was conducted to assess adhesion, while wettability was evaluated using analysis of variance and analyses. The level of statistical significance was set at < 0.05.
RESULTS
FTIR analysis confirmed that a chemical between OFPA and PEEK was established. The samples showed a significant increase in the contact angle after 30 s of plasma application (CA = 88.2 ± 7.3). The contact angle decreased again by increasing the surface modification to 60 s (CA = 64.33 ± 5.5). Examining the surface morphology of the samples shows an increase in surface roughness with increasing plasma time up to 60 s. The number of adherent colonies was the lowest in 30 s group, but it was not statistically significant ( = 0.658).
CONCLUSION
No statistically significant difference in CFU/mL count was found between groups. The contact angle of the 30 s group was significantly higher than the control group.
PubMed: 38425323
DOI: No ID Found -
Materials (Basel, Switzerland) Aug 2023The processes of interaction of liquid droplets with solid surfaces have become of interest to many researchers. The achievements of world science should be used for the... (Review)
Review
The processes of interaction of liquid droplets with solid surfaces have become of interest to many researchers. The achievements of world science should be used for the development of technologies for spray cooling, metal hardening, inkjet printing, anti-icing surfaces, fire extinguishing, fuel spraying, etc. Collisions of drops with surfaces significantly affect the conditions and characteristics of heat transfer. One of the main areas of research into the interaction of drops with solid surfaces is the modification of the latter. Changes in the hydrophilic and hydrophobic properties of surfaces give the materials various functional properties-increased heat transfer, resistance to corrosion and biofouling, anti-icing, etc. This review paper describes methods for obtaining hydrophilic and hydrophobic surfaces. The features of the interaction of liquid droplets with such surfaces are considered. The existing and possible applications of modified surfaces are discussed, as well as topical areas of research.
PubMed: 37687631
DOI: 10.3390/ma16175932 -
Biomolecules Aug 2023Solid surfaces have been shown to affect the aggregation and assembly of many biomolecular systems. One important example is the formation of protein fibrils, which can...
Solid surfaces have been shown to affect the aggregation and assembly of many biomolecular systems. One important example is the formation of protein fibrils, which can occur on a range of biological and synthetic surfaces. The rate of fibrillation depends on both the protein structure and the surface chemistry, with the different molecular and oligomer structures adopted by proteins on surfaces likely to be crucial. In this paper, the aggregation of the model amyloidogenic peptide, Aβ(16-22), corresponding to a hydrophobic segment of the amyloid beta protein on a gold surface is studied using molecular dynamics simulation. Previous simulations of this peptide on gold surfaces have shown that it adopts conformations on surfaces that are quite different from those in bulk solution. These simulations show that this then leads to significant differences in the oligomer structures formed in solution and on gold surfaces. In particular, oligomers formed on the surface are low in beta-strands so are unlike the structures formed in bulk solution. When oligomers formed in solution adsorb onto gold surfaces they can then restructure themselves. This can then help explain the inhibition of Aβ(16-22) fibrillation by gold surfaces and nanoparticles seen experimentally.
Topics: Amyloid beta-Peptides; Cytoskeleton; Gold; Molecular Dynamics Simulation; Nanoparticles
PubMed: 37627326
DOI: 10.3390/biom13081261 -
Cerebral Cortex (New York, N.Y. : 1991) Oct 2021Recent advances in neuroimaging have augmented numerous findings in the human reasoning process but have yielded varying results. One possibility for this inconsistency... (Meta-Analysis)
Meta-Analysis
Recent advances in neuroimaging have augmented numerous findings in the human reasoning process but have yielded varying results. One possibility for this inconsistency is that reasoning is such an intricate cognitive process, involving attention, memory, executive functions, symbolic processing, and fluid intelligence, whereby various brain regions are inevitably implicated in orchestrating the process. Therefore, researchers have used meta-analyses for a better understanding of neural mechanisms of reasoning. However, previous meta-analysis techniques include weaknesses such as an inadequate representation of the cortical surface's highly folded geometry. Accordingly, we developed a new meta-analysis method called Bayesian meta-analysis of the cortical surface (BMACS). BMACS offers a fast, accurate, and accessible inference of the spatial patterns of cognitive processes from peak brain activations across studies by applying spatial point processes to the cortical surface. Using BMACS, we found that the common pattern of activations from inductive and deductive reasoning was colocalized with the multiple-demand system, indicating that reasoning is a high-level convergence of complex cognitive processes. We hope surface-based meta-analysis will be facilitated by BMACS, bringing more profound knowledge of various cognitive processes.
Topics: Bayes Theorem; Brain; Humans; Magnetic Resonance Imaging; Neuroimaging; Problem Solving
PubMed: 34180523
DOI: 10.1093/cercor/bhab174 -
BioRxiv : the Preprint Server For... Jan 2023The attachment of bacteria onto a surface, consequent signaling, and the accumulation and growth of the surface-bound bacterial population are key initial steps in the...
The attachment of bacteria onto a surface, consequent signaling, and the accumulation and growth of the surface-bound bacterial population are key initial steps in the formation of pathogenic biofilms. While recent reports have hinted that the stiffness of a surface may affect the accumulation of bacteria on that surface, the processes that underlie bacterial perception of and response to surface stiffness are unknown. Furthermore, whether, and how, the surface stiffness impacts biofilm development, after initial accumulation, is not known. We use thin and thick hydrogels to create stiff and soft composite materials, respectively, with the same surface chemistry. Using quantitative microscopy, we find that the accumulation, motility, and growth of the opportunistic human pathogen respond to surface stiffness, and that these are linked through cyclic-di-GMP signaling that depends on surface stiffness. The mechanical cue stemming from surface stiffness is elucidated using finite-element modeling combined with experiments - adhesion to stiffer surfaces results in greater changes in mechanical stress and strain in the bacterial envelope than does adhesion to softer surfaces with identical surface chemistry. The cell-surface-exposed protein PilY1 acts as a mechanosensor, that upon surface engagement, results in higher cyclic-di-GMP levels, lower motility, and greater accumulation on stiffer surfaces. PilY1 impacts the biofilm lag phase, which is extended for bacteria attaching to stiffer surfaces. This study shows clear evidence that bacteria actively respond to different stiffness of surfaces where they adhere perceiving varied mechanical stress and strain upon surface engagement.
PubMed: 36747833
DOI: 10.1101/2023.01.26.525810 -
Annals of Translational Medicine Jul 2022Surface-based cortical morphological patterns provide insight into the neural mechanisms of Parkinson's disease (PD). Explorations of the relationship between these...
BACKGROUND
Surface-based cortical morphological patterns provide insight into the neural mechanisms of Parkinson's disease (PD). Explorations of the relationship between these patterns and the clinical assessment and treatment effects could be used to inform early intervention and treatment planning.
METHODS
We recruited 78 PD patients who underwent presurgical evaluation and 55 healthy controls. We assessed neocortical sulcal depth, gyrification index, and fractal dimension and applied a general linear model using the multivariate Hotelling's -test to determine the joint effect of surface-based shape abnormalities in PD. The relationship between the neuroimaging pattern and clinical assessment was investigated using a multivariate linear regression model. A machine learning model based on surfaced-based features was used to predict responses to medication and deep brain stimulation (DBS).
RESULTS
The surface-based neuroimaging pattern of PD included decreases in morphological metrics in the gyrus (left: F=4.32; right: F=4.13), insular lobe (left: F=4.87; right: F=4.53), paracentral lobe (left: F=4.01; right: F=4.26), left posterior cingulate cortex (F=4.48), and left occipital lobe (F=4.27, P<0.01). This pattern was significantly associated with cognitive performance and motor symptoms (P<0.01). The machine learning model using morphological metrics was able to predict the drug response in the tremor score (R=-0.34, P<0.01) and postural instability and gait disorders score (R=0.24, P=0.04).
CONCLUSIONS
We identified the surface-based neuroimaging pattern associated with PD and explored its association with clinical assessment. Our findings suggest that these morphological indicators have potential value in informing personalized medicine and patient management.
PubMed: 35957730
DOI: 10.21037/atm-22-630 -
Environmental Science and Ecotechnology Apr 2020Particulate-associated trace metals have been regarded as an important pollution source for urban surface runoff. Cd, Pb, Cu, Zn and total solids (TS) washed off two...
Particulate-associated trace metals have been regarded as an important pollution source for urban surface runoff. Cd, Pb, Cu, Zn and total solids (TS) washed off two different surfaces (low-elevated facade and road surfaces) under two kinds of antecedent environmental conditions (dry and snow-melting) were determined in this study. Wet-vacuuming sweeping (WVS) and surface washing (SW) methods, representing the maximum pollution potential and common rainfall-induced wash-off condition respectively, were used to collect the particulate matters. The result shows that the wash-off concentrations of trace metals were found in the order of Cd (2.28 ± 2.08 μg/l) < Pb (435.85 ± 412.61 μg/l) < Cu (0.93 ± 0.61 mg/l) < Zn (2.52 ± 2.30 mg/l). The snow-melting process had a considerable influence on the wash-off concentrations of the trace metals on both road and facade surfaces. It reduced >38% and >79% of metals and TS concentrations in the facade surface and road surface runoff respectively. The wash-off concentrations of Cd, Cu, and Zn on the road surface 45-780% higher than those on the facade surfaces. The sensitivity analysis based on the Bayesian network indicates that the wash-off concentrations of metals were mainly dependent on the antecedent environmental conditions or the surface properties while the sampling methods had a minor influence. Therefore, to accurately model the pollutant migration in the surface runoff requires an improving method considering different surfaces and antecedent environment conditions.
PubMed: 36160919
DOI: 10.1016/j.ese.2020.100017 -
Advances in Colloid and Interface... Mar 2023As nanocarriers (NCs) can improve the solubility of drugs, prevent their degradation by gastrointestinal (GI) enzymes and promote their transport across the mucus gel... (Review)
Review
As nanocarriers (NCs) can improve the solubility of drugs, prevent their degradation by gastrointestinal (GI) enzymes and promote their transport across the mucus gel layer and absorption membrane, the oral bioavailability of these drugs can be substantially enhanced. All these properties of NCs including self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), liposomes, polymeric nanoparticles, inorganic nanoparticles and polymeric micelles depend mainly on their surface chemistry. In particular, interaction with food, digestive enzymes, bile salts and electrolytes, diffusion behaviour across the mucus gel layer and fate on the absorption membrane are determined by their surface. Bioinert surfaces limiting interactions with gastrointestinal fluid and content as well as with mucus, adhesive surfaces providing an intimate contact with the GI mucosa and absorption enhancing surfaces can be designed. Furthermore, charge converting surfaces shifting their zeta potential from negative to positive directly at the absorption membrane and surfaces providing a targeted drug release are advantageous. In addition to these passive surfaces, even active surfaces cleaving mucus glycoproteins on their way through the mucus gel layer can be created. Within this review, we provide an overview on these different surfaces and discuss their impact on the performance of NCs in the GI tract.
Topics: Drug Carriers; Drug Delivery Systems; Nanoparticles; Biological Availability; Administration, Oral; Gastrointestinal Tract
PubMed: 36780780
DOI: 10.1016/j.cis.2023.102848