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Langmuir : the ACS Journal of Surfaces... Jun 2023The sequence of water adsorption is significant to understand the mechanism of clay-water interactions on clay mineral surfaces. Kaolinite is a typical non-expansive...
The sequence of water adsorption is significant to understand the mechanism of clay-water interactions on clay mineral surfaces. Kaolinite is a typical non-expansive phyllosilicate clay, and its water adsorption is generally recognized to occur on the basal surfaces of aluminum-silicate particles, whereas edge surface adsorption is prevalently overlooked due to its complexity despite its potential large surface area available for adsorption. In this study, we used molecular dynamics and metadynamics simulation to quantitatively assess the free energy of water adsorption, viz., matric potential, on kaolinite for four types of external surfaces, namely, a basal silicon-oxygen (Si-O) surface, a basal aluminum-oxygen (Al-O) surface, and edge surfaces with deprotonation and protonation. The results show that edge surfaces exhibit adsorption sites that are more active with the lowest matric potential of -1.86 GPa, lower than that of basal surfaces (-0.92 GPa), due to protonation and deprotonation processes of the dangling oxygen. The adsorption isotherm from 0.2% of relative humidity (RH) was measured and analyzed using an augmented Brunauer-Emmet-Teller model to separate the edge and basal surface adsorption, further verifying that edge surface adsorption may prevail in kaolinite and occur earlier than base surface adsorption in RH less than 5%.
PubMed: 37220326
DOI: 10.1021/acs.langmuir.2c03282 -
IEEE Transactions on Haptics 2022Thin von Frey monofilaments are a clinical tool used worldwide to assess touch deficits. One's ability to perceive touch with low-force monofilaments (0.008 - 0.07 g)...
Thin von Frey monofilaments are a clinical tool used worldwide to assess touch deficits. One's ability to perceive touch with low-force monofilaments (0.008 - 0.07 g) establishes an absolute threshold and thereby the extent of impairment. While individual monofilaments bend at defined forces, there are no empirical measurements of the skin surface's response. In this work, we measure skin surface deformation at light-touch perceptual limits, by adopting an imaging approach using 3D digital image correlation (DIC). Generating point cloud data from three cameras surveilling the index finger pad, we reassemble and stitch together multiple 3D surfaces. Then, in response to each monofilament's indentation over time, we quantify strain across the skin surface, radial deformation emanating from the contact point, penetration depth into the surface, and area between 2D cross-sections. The results show that the monofilaments create distinct states of skin deformation, which align closely with just noticeable percepts at absolute detection and discrimination thresholds, even amidst variance between individuals and trials. In particular, the resolution of the DIC imaging approach captures sufficient differences in skin deformation at threshold, offering promise in understanding the skin's role in perception.
Topics: Fingers; Humans; Skin; Touch; Touch Perception
PubMed: 34951855
DOI: 10.1109/TOH.2021.3138350 -
Angewandte Chemie (International Ed. in... Dec 2019We report a novel modulation strategy by introducing transition metals into NiS nanosheets (NSs) to flexibly optimize the electronic configurations and atomic... (Review)
Review
We report a novel modulation strategy by introducing transition metals into NiS nanosheets (NSs) to flexibly optimize the electronic configurations and atomic arrangement. The Co-NiS NSs exhibit excellent hydrogen evolution reaction (HER) performance with an overpotential of 80 mV at j=10 mA cm and long-term stability of 90 h in alkaline media. The turnover frequencies (TOFs) of 0.55 and 4.1 s at an overpotential of 100 and 200 mV also confirm their remarkable performance. DFT calculations reveal that the surface dopants abnormally sensitize surface Ni-3d bands in the long-range order towards higher electron-transfer activity, acting as the electron-depletion center. Meanwhile, the high lying surface S-sites possess substantially high selectivity for splitting the adsorbing H O that guarantee the high HER performance within alkaline conditions. This work opens opportunities for enhancing water splitting by atomic-arrangement-assisted electronic modulation via a facile doping strategy.
PubMed: 31612576
DOI: 10.1002/anie.201911470 -
Journal of Colloid and Interface Science May 2023Achieving spontaneous, rapid, and long-distance liquid transport is crucial for many practical applications such as phase change heat transfer and reactions at...
HYPOTHESIS
Achieving spontaneous, rapid, and long-distance liquid transport is crucial for many practical applications such as phase change heat transfer and reactions at solid-liquid interfaces. Surface nanotexturing has been widely reported to improve the wickability of microtextured metal surfaces. Although surface nanotextures show high capillary pressure, the high fluid flow resistance through nanotextures prevents fluid transport. The underlying mechanisms responsible for the enhanced wickability of nanotextured surfaces are still unclear.
EXPERIMENTS
Herein, we prepared a variety of microtextures and nanotextures on copper surfaces by femtosecond laser micromachining and chemical oxidation, respectively. The wickability of these textured surfaces was quantitively compared by measuring wicking coefficient and capillary rise speed. We designed experiments to eliminate any possible effects of surface oxidation and metal composition on wickability. A theoretical model describing the vertical and horizontal capillary flow in V-shaped microgrooves was proposed and utilized to analyze the experimental results. The effects of time-dependent wettability on wickability were also examined.
FINDINGS
Surface nanotexturing can enhance surface wettability while altering the micrometer-scale structural characteristics. The greatly enhanced wickability of nanotextured surfaces can only be observed when the surface microtextures have a very small aspect ratio. Otherwise, for metal surfaces with fine microgrooves, the latter effect is more pronounced, and thus the surface wickability may deteriorate after preparing surface nanotextures; for surfaces with wide microgrooves, both effects are minimal, and the surface wickability enhances only marginally after surface nanotexturing. Furthermore, the wickability of microtextured surfaces will decay rapidly due to the adsorption of airborne organics, whereas adding surface nanotextures can significantly inhibit this degradation. The anti-contamination capability of surface nanotextures is considered likely to be a potential mechanism responsible for the greatly enhanced wickability of nanotextured surfaces noted in some studies.
PubMed: 36791477
DOI: 10.1016/j.jcis.2023.01.148 -
Computers in Biology and Medicine Oct 2022Burn scar treatment is a difficult subject to address since the improper therapy can have a significant impact on people's quality of life. The evaluation of medical...
Burn scar treatment is a difficult subject to address since the improper therapy can have a significant impact on people's quality of life. The evaluation of medical therapy over time should be based on objective measurement of the severity of burn scars and their progression. Unfortunately, most clinical assessments of scars are still reliant on physicians' subjective exams of patients. A profitable method to overcome the limitations of subjective assessment could be to leverage 3D scanning technologies. These could be used to retrieve the surface topology of burns. Accordingly, the goal of this study is to provide an objective approach for analysing the surface topology of burn scars using 3D scanning and roughness-based evaluation. In particular, two types of ISO-compliant profile and surface filters (Gaussian and Wavelet) derived from the analysis of roughness in the mechanical sector are implemented to discriminate form from roughness of scars. Once retrieved, the roughness surface is processed to derive a set of statistical parameters describing the scar surface topology. Three case studies were used to derive these parameters (a synthetic surface, an ostrich-skin surface and a set of scars). After the surface's roughness was determined, a comparison between healthy and unhealthy skin could be established. The devised methods prove their effectiveness in correctly retrieving the main surface characteristics of a burn scar. Therefore, by using the proposed method it will be possible to evaluate the effectiveness of medical therapy by comparing the healthy and scarred skin of a single subject.
Topics: Burns; Cicatrix; Humans; Quality of Life; Skin
PubMed: 35994934
DOI: 10.1016/j.compbiomed.2022.105945 -
International Journal of Molecular... Aug 2021Polyetheretherketone (PEEK), due to its excellent mechanical and physico-chemical parameters, is an attractive substitute for hard tissues in orthopedic applications....
Polyetheretherketone (PEEK), due to its excellent mechanical and physico-chemical parameters, is an attractive substitute for hard tissues in orthopedic applications. However, PEEK is hydrophobic and lacks surface-active functional groups promoting cell adhesion. Therefore, the PEEK surface must be modified in order to improve its cytocompatibility. In this work, extreme ultraviolet (EUV) radiation and two low-temperature, EUV induced, oxygen and nitrogen plasmas were used for surface modification of polyetheretherketone. Polymer samples were irradiated with 100, 150, and 200 pulses at a 10 Hz repetition rate. The physical and chemical properties of EUV and plasma modified PEEK surfaces, such as changes of the surface topography, chemical composition, and wettability, were examined using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and goniometry. The human osteoblast-like MG63 cells were used for the analysis of cell viability and cell adhesion on all modified PEEK surfaces. EUV radiation and two types of plasma treatment led to significant changes in surface topography of PEEK, increasing surface roughness and formation of conical structures. Additionally, significant changes in the chemical composition were found and were manifested with the appearance of new functional groups, incorporation of nitrogen atoms up to ~12.3 at.% (when modified in the presence of nitrogen), and doubling the oxygen content up to ~25.7 at.% (when modified in the presence of oxygen), compared to non-modified PEEK. All chemically and physically changed surfaces demonstrated cyto-compatible and non-cytotoxic properties, an enhancement of MG63 cell adhesion was also observed.
Topics: Benzophenones; Biocompatible Materials; Cell Adhesion; Cell Line; Humans; Nitrogen; Osteoblasts; Oxygen; Plasma Gases; Polymers; Surface Properties; Ultraviolet Rays
PubMed: 34445159
DOI: 10.3390/ijms22168455 -
Micromachines Mar 2023The controlled and efficient formation of oxygen vacancies on the surface of metal oxide semiconductors is required for their use in gas sensors. This work addresses the...
The controlled and efficient formation of oxygen vacancies on the surface of metal oxide semiconductors is required for their use in gas sensors. This work addresses the gas-sensing behaviour of tin oxide (SnO) nanoparticles for nitrogen oxide (NO), NH, CO, and HS detection at various temperatures. Synthesis of SnO powder and deposition of SnO film is conducted using sol-gel and spin-coating methods, respectively, as these methods are cost-effective and easy to handle. The structural, morphological, and optoelectrical properties of nanocrystalline SnO films were studied using XRD, SEM, and UV-visible characterizations. The gas sensitivity of the film was tested by a two-probe resistivity measurement device, showing a better response for the NO and outstanding low-concentration detection capacity (down to 0.5 ppm). The anomalous relationship between specific surface area and gas-sensing performance indicates the SnO surface's higher oxygen vacancies. The sensor depicts a high sensitivity at 2 ppm for NO with response and recovery times of 184 s and 432 s, respectively, at room temperature. The result demonstrates that oxygen vacancies can significantly improve the gas-sensing capability of metal oxide semiconductors.
PubMed: 37420962
DOI: 10.3390/mi14040728 -
IEEE Transactions on Visualization and... Feb 2021Structured Adaptive Mesh Refinement (Structured AMR) enables simulations to adapt the domain resolution to save computation and storage, and has become one of the...
Structured Adaptive Mesh Refinement (Structured AMR) enables simulations to adapt the domain resolution to save computation and storage, and has become one of the dominant data representations used by scientific simulations; however, efficiently rendering such data remains a challenge. We present an efficient approach for volume- and iso-surface ray tracing of Structured AMR data on GPU-equipped workstations, using a combination of two different data structures. Together, these data structures allow a ray tracing based renderer to quickly determine which segments along the ray need to be integrated and at what frequency, while also providing quick access to all data values required for a smooth sample reconstruction kernel. Our method makes use of the RTX ray tracing hardware for surface rendering, ray marching, space skipping, and adaptive sampling; and allows for interactive changes to the transfer function and implicit iso-surfacing thresholds. We demonstrate that our method achieves high performance with little memory overhead, enabling interactive high quality rendering of complex AMR data sets on individual GPU workstations.
PubMed: 33048750
DOI: 10.1109/TVCG.2020.3030470 -
Biomedicines Oct 2021Nanoparticles (NPs) in contact with a biological medium are rapidly comprehended by a number of protein molecules resulting in the formation of an NP-protein complex... (Review)
Review
Nanoparticles (NPs) in contact with a biological medium are rapidly comprehended by a number of protein molecules resulting in the formation of an NP-protein complex called protein corona (PC). The cell sees the protein-coated NPs as the synthetic identity is masked by protein surfacing. The PC formation ultimately has a substantial impact on various biological processes including drug release, drug targeting, cell recognition, biodistribution, cellular uptake, and therapeutic efficacy. Further, the composition of PC is largely influenced by the physico-chemical properties of NPs viz. the size, shape, surface charge, and surface chemistry in the biological milieu. However, the change in the biological responses of the new substrate depends on the quantity of protein access by the NPs. The PC-layered NPs act as new biological entities and are recognized as different targeting agents for the receptor-mediated ingress of therapeutics in the biological cells. The corona-enveloped NPs have both pros and cons in the biological system. The review provides a brief insight into the impact of biomolecules on nanomaterials carrying cargos and their ultimate fate in the biological milieu.
PubMed: 34680613
DOI: 10.3390/biomedicines9101496 -
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