Support Surface Research Articles

Congress Takes a Positive Swing at an Unsung Public Health Crisis: Preventing Pressure Injuries in Veterans Affairs Facilities.

Congress Takes a Positive Swing at an Unsung Public Health Crisis: Preventing Pressure Injuries in Veterans Affairs Facilities.

АСИМПТОТИЧЕСКИЙ ПОДХОД К РЕШЕНИЮ КОНТАКТНОЙ ЗАДАЧИ ДЛЯ ТЕЛА КАЧЕНИЯ С ТОНКИМ ДЕФОРМИРУЕМЫМ ОБОДОМ

On the basis of an asymptotic approach to solving the elasticity theory boundary value problem for a thin strip rigidly linked to a non-deformable base, the differential equations are derived for determining the normal and shear loads distributed on the strip face free from fastening. These equations are used to solve the contact problem for a rigid cylinder with a thin elastic rim with a non-deformable horizontal rough support surface. The cylinder loading by a vertical force is considered for a given cylinder center settling. The calculated diagrams of contact pressure and shear contact stresses are obtained. In contrast to the previously used methods, the developed technique makes it possible to take into account the presence of adhesion and slip zones in the contact area, as well as to use a mathematically strict solution of the constitutive equations for contact pressure and shear contact stress. The value of the vertical force acting on the rigid cylinder for a given cylinder center displacement is determined. The stress tensor intensity distribution in the rim is established. The results of the developed technique application are compared with the calculated estimates obtained on the basis of the exact solution of the boundary value problem for a strip of arbitrary thickness and within the method, involving the use of the Winkler base simplified model. The dependences of the results error for the developed method on the thickness and Poisson's ratio of the rim material are obtained. The paper describes the effect of the rim-support surface friction coefficient on the contact pressure, shear contact pressure, and the maximum intensity of the stress tensor in the rim. It is concluded that it is reasonable to use the developed technique at solving contact problems for rolling elements with a relatively thin elastic rim.

지지면 변화에 따른 네발기기 자세 운동이 뭇갈래근과 척추세움근의 두께 및 근 긴장도에 미치는 영향

The purpose of this study is to investigate the effect of quadruped exercise according to the change of the support surface on the muscle thickness and muscle tone of the multifidus and erector spinae muscles. Thity healthy adults (16 males and 14 females) voluntarily participated in the experiment. The Q (Quadruped) and Q-L (Quadruped-Lifting right leg) exercises were performed on a stable support surface; whereas the Q-LT (Quadruped-Lifting right leg using TOGU dynamic airchusion) and Q-LS (Quadruped-Lifting right leg using Sling) exercises were performed on an unstable support surface. Outcome measurement included muscle thickness and muscle tone measurement using ultrasound equipment and Myoton, respectively. Repeated measures ANOVA was used for data analysis. The result of the study showed that in Q-L, Q-LT, and Q-LS, the muscle thickness of the multifidus and erector spinae was significantly increased compared to Q (p<.05). The muslce tone of the multifidus in Q-LT and Q-LS, increased compared to Q (p<.05). The muscle tone of the erector spinae muscle was significantly increased in Q-L, Q-LT and Q-LS compared to Q (p<.05). The muscle thickness was significantly increased in the unstable support surfaces in Q-LT and Q-LS compared to the stable support surfaces of Q and Q-L (p<.05). However, a significant difference between Q-LT and Q-LS was absent, which were the unstable support surfaces. Therefore, the results of this study showed that the quadruped exercise was more effective on an unstable support surface. This result can be used as useful data for the prescription and application of various exercises in clinical practice.

Influence of carbon support surface modification on the performance of nickel catalysts in carbon dioxide hydrogenation

The interaction between metal nanoparticles and a support is of key importance in catalysis. In this study, we demonstrate that the introduction of oxygen- or nitrogen-containing surface groups on a graphite nanoplatelet support influences the performance of nickel supported catalysts during CO2 hydrogenation. By careful design of the synthesis conditions, the Ni nanoparticle size of the fresh catalysts was not affected by the type of support surface groups. A combination of H2 chemisorption and high resolution TEM demonstrates that the available metal surface depends on the interaction with the carbon support. The amination treatment to introduce nitrogen-containing groups results in the weakest interaction between the Ni and the support, showing the highest initial Ni weight-based activity, although at the expense of nanoparticle stability. Hence initial enhancement in activity is not always optimal for long term catalysis. The use of carbon with a higher density of oxygen functional groups that are stable above 350 °C, is beneficial for preventing deactivation due to particle growth. Furthermore, small amounts of contaminants can have a substantial influence on the CH4 selectivity at low conversions.

身体平衡における体性感覚入力の影響について

Sensory inputs used by the central nervous system to generate commands for postural control mainly come from three sources: the vestibular system, the somatosensory system, and the visual system. Spatial orientation, or the ability to recognize one's own position, direction, and posture in space accurately, is formed based on information obtained from the above three sources combined with auditory and other information. In postural control, the somatosensory system provides the central nervous system with information about the position and motion of the body with respect to the support surface. Foam posturography is a clinical application of the phenomenon in which a decrease in somatosensory input exacerbates postural sway. The lower limb somatosensory input is disturbed by standing on foam rubber. Foam posturography can thus be used to suggest a diagnosis of vestibulopathy and to assess the dependence of postural control on somatosensory input. The dependence of postural control on somatosensory input in patients with persistent postural-perceptual dizziness (PPPD) remains controversial, and further research on changes in the weighting of various sensory inputs and their mechanisms in PPPD are expected.

Comparison of covalent and in situ immobilization of Candida antarctica lipase A on a flexible nanoporous material.

In this study, Candida antarctica lipase A, which has a unique applicability for the conversion of highly branched and bulky substrates, was subjected to immobilization on the flexible nanoporous MIL-53(Fe) by two approaches: covalent coupling and in situ immobilization method. The pre-synthesized support under ultrasound irradiation was incubated with N,N-dicyclohexylcarbodiimide to mediate the covalent attachment between the carboxylic groups on the support surface and amino groups of enzyme molecules. The in situ immobilization in which the enzyme molecules directly were embedded into the metal-organic framework was performed under mild operating conditions in a facile one-step manner. Both immobilized derivatives of the enzyme were characterized by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, FT-IR spectra, and energy-dispersive X-ray spectroscopy. In the in situ immobilization method, the enzyme molecules were efficiently encapsulated within the support with a high loading capacity (220 ± 5mg/g support). On the other hand, the covalent attachment resulted in immobilizing much lower concentrations of the enzyme (20 ± 2.2mg/g support). Although both immobilized derivatives of lipase showed broader pH and temperature tolerance relative to the soluble enzyme, the biocatalyst, which was prepared through in situ method, was more stable at elevated temperatures than the covalently immobilized lipase. Furthermore, in situ immobilized derivatives of Candida antarctica lipase A could be efficiently reused for at least eight cycles (> 70% of retained activity). In contrast, its covalently immobilized counterpart showed a drastic decrease in activity after five cycles (less than 10% of retained activity at the end of 6 rounds).

Activated carbon supported nickel catalyst for selective CO2 hydrogenation to synthetic methane under contactless induction heating

The use of CO2 methanation in the power-to-gas (PtG) technology chains has received increasing attention in recent years for clean energy and sustainable development. In this work, macroscopic mesoporous nickel catalyst was prepared and evaluated for selective CO2 hydrogenation to CH4 using commercial activated carbon (AC) pellets. Catalyst samples were fully characterized by liquid N2 adsorption-desorption, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), scanning and transmission electron microscopy (SEM/TEM). Catalytic performances were investigated under various reaction conditions with both direct induction heating (IH) and conventional indirect Joule heating (JH) modes. Results indicated that by simple thermal treatment, the surface and textural properties of the macroscopic carbon support could be greatly modified by improving the dispersion of metal sites and thus the catalytic performance. The advantages of IH combined with the inherent high thermal and electrical conductivity of the prepared materials could effectively avoid the temperature runaway and enhance the CO2 activation at relatively low reaction temperature. By comparison to the classical indirect JH mode, the resulting macroscopic nickel catalysts showed improving catalytic performances for CO2 methanation under IH mode. The efficient heat management under direct IH mode also prevented coke formation on the catalyst surface which contributes to its high stability as a function of time-on-stream.

Preparation of heterogeneous Fenton catalyst with residual carbon separated from coal gasification slag as carrier

ABSTRACT This study prepares a magnetite (Fe3O4)-based Fenton-like catalyst based on the residual carbon separated from coal gasification slag as a support by the chemical precipitation method. The catalysts are characterized using XRD, SEM-EDX, and N2 adsorption-desorption methods. In the process, the adsorption capacity, catalytic activity under various conditions, and catalyst reusability were evaluated with methylene blue as the target pollutant. According to SEM results, Fe3O4 particles are attached to the pore and surface of the residual carbon support and have good dispersion. BET findings demonstrate that Fe3O4/residual carbon catalyst has a greater surface area and pore volume than residual carbon support. The removal efficiency of MB by adsorption of Fe3O4/residual carbon catalyst is less than 10% after 120 min. But 2.4Fe-UC catalyst shows 2-h removal rates of 98% when the optimum removal efficiency of MB is under the following conditions: 2.5 mmol/L H2O2, 0.2 g/L catalysts for 50 mg/L MB at an initial pH of 3. Notably, outstanding catalytic stability and reusability of the 2.4Fe-RC catalyst have been revealed as it can be reused 6 times with>80% of the MB removal efficiency.

Effect of preparation method on active sites variation for catalytic oxidation of toluene over Pt/MCM-48

Toluene oxidation behavior has been investigated on a series of catalysts with Pt supported on MCM-48 that has a large specific surface area & easy-transported three-dimensional channels prepared by four different methods. It was found that various introduction ways of Pt have a great influence on both Pt content and state, resulting in a difference in catalytic oxidation performance. Pt/M48-PG prepared via the post-grafting method possesses both the highest Pt content (0.83 wt%) and active species of Pt0 & surface labile oxygen (accounting for 46% and 55%, respectively), resulting in the lowest T90 (155 °C) and the highest TOF (7.92 ×10−3·s−1). Characterization results showed that the amine functional groups could be successfully grafted onto the support's surface, which is beneficial for the binding of platinum precursor with support, leading to the high actual loading efficiency and dispersion of Pt, both of which contribute to retaining more Pt0 and surface labile oxygen active species.

The Relationship Between the Cross-Linker on Chitosan-Coated Magnetic Nanoparticles and the Properties of Immobilized Papain.

The immobilized enzymes' properties can be affected by cross-linkers on the surface of supports. To study how cross-linkers alter enzymes function, chitosan-coated magnetic nanoparticles (CMNPs) with immobilized papain were prepared using glutaraldehyde and or genipin, and then, the properties of the nanoparticles and the immobilized enzymes were assessed. The Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), and X-Ray Diffraction (XRD) results showed that the CMNPs were prepared and papain molecules were immobilized on CMNPs by glutaraldehyde (CMNP-Glu-Papain) or by genipin (CMNP-Gen-Papain). Also, the results associated with enzymes activity indicated that the immobilization by glutaraldehyde and genipin increased the pH optimum of papain from 7 to 7.5 and 9, respectively. The kinetic results indicated that the immobilization by genipin slightly affects the enzyme affinity to the substrate. The stability results showed that CMNP-Gen-Papain has more thermal stability than CMNP-Glu-Papain and papain immobilization on CMNPs by genipin leads to stabilization of the enzyme in the presence of polar solvents, probably due to the more hydroxyl groups on CMNPs activated by genipin. In conclusion, this study suggests that there is a relationship between the types of cross-linker on the surface of supports, and the mechanism of action, kinetic parameters, and the stability of immobilized papain.

Slow pyrolysis experimental investigation of biomass tar formation and hydrogen production by tar reforming

The characteristics of pyrolysis tar and catalytic hydrogen production during tar reforming with catalysts were investigated. Through the pyrolysis experiment of wheat straw at 400–800 °C, the change of tar yield and tar composition with pyrolysis temperature was obtained. In order to remove tar, different nickel-based catalysts were prepared and catalytic experiments were carried out. The results showed that the pyrolysis tar yield first increased and then decreased with the increase of temperature, and the maximum tar yield was 32.82% at 700 °C. The generation of tar mainly comes from the thermal decomposition of biomass before 500 °C, the homogeneous reactions of tar compositions begin to occur after 500 °C. Through the characterization of the catalysts and their catalytic performance, it was found that due to the interaction of Ni and Ce on the support surface, Ni particles were more evenly distributed on the surface of the support. By adding Ce into Ni/HZSM-5, more oxygen vacancies are formed on the catalyst surface, which makes the catalyst have higher reducibility and more active sites. Compared with 9Ni/HZSM-5, 9Ni3Ce/HZSM-5 has a better catalytic performance with the tar conversion of 89.34% and H2 composition of 0.43.

In Situ Construction of MnO2–Co3O4 Nanosheet Heterojunctions on Co@NCNT Surfaces for Oxygen Evolution

Electrocatalytic water splitting is still circuitous and controversial because of the lack of highly active electrocatalysts to decrease the overpotential. Herein, we report a feasible method for constructing heterojunctions of MnO2-Co3O4 nanosheets on Co@NCNT support surfaces (MnO2-Co3O4/Co@NCNT) by spontaneous redox reactions. Experimental results indicate that Co embedded in Co@NCNT can be used as the carbon support and anchoring sites for heterojunctions, thus exposing a large number of active sites, adjusting the surface electronic structure, changing the OER rate-determining step of the catalyst, and reducing the reaction energy barrier. Besides, the in situ formation of MnO2-Co3O4 nanosheets on Co@NCNT inhibits the loss and aggregation of the catalyst, leading to robust structural stability. Therefore, the synergistic effects of these factors provide multi-functional active sites to enhance the intrinsic activity and achieve maximum catalytic performances. To deliver a current density of 10 mA cm-2, the catalyst of MnO2-Co3O4/Co@NCNT achieves an overpotential (η) of 303 mV in 1.0 M KOH media for OER. This simple redox strategy can be easily extended to prepare other ultrathin transition-metal oxide heterojunctions, which could be applied not only for water splitting but also for other energy conversion and storage technologies.

Atmospheric-Pressure Plasma-Induced In Situ Polymerization of Liquid Silsesquioxane Monomer for the Synthesis of Polysilsesquioxane Nanocomposite Membranes with Sub-Nanometer Pores for Molecular Separation

Plasma-induced polymerization of liquid silsesquioxane monomer (1,2-bis(triethoxysilyl)ethane, BTESE) at the gas–liquid interface was achieved at room temperature by employing an atmospheric-pressure plasma jet. The polymerization of the liquid monomer under exposure to atmospheric-pressure plasma resulted in the formation of a thin polysilsesquioxane layer at the immediate surface of the porous support. The confined polymerization at the plasma-liquid interface was demonstrated to be beneficial for preparing nanocomposite membranes with a thin selective layer on top of the porous support. The BTESE-derived polysilsesquioxane membrane exhibited high selectivity for gas separation (H2/CH4 = 195) based on the molecular sieving mechanism.

Fabricating Robust Pt Clusters on Sn-Doped CeO2 for CO Oxidation: A Deep Insight into Support Engineering and Surface Structural Evolution.

The size effect on nanoparticles, which affects the catalysis performance in a significant way, is crucial. The tuning of oxygen vacancies on metal-oxide support can help reduce the size of the particles in active clusters of Pt, thus improving catalysis performance of the supported catalyst. Herein, Ce-Sn solid solutions (CSO) with abundant oxygen vacancies have been synthesized. Activated by simple CO reduction after loading Pt species, the catalytic CO oxidation performance of Pt/CSO was significantly better than that of Pt/CeO2 . The reasons for the elevated activity were further explored regarding ionic Pt single sites being transformed into active Pt clusters after CO reduction. Due to more exposed oxygen vacancies, much smaller Pt clusters were created on CSO (ca. 1.2 nm) than on CeO2 (ca. 1.8 nm). Consequently, more exposed active Pt clusters significantly improved the ability to activate oxygen and directly translated to the higher catalytic oxidation performance of activated Pt/CSO catalysts in vehicle emission control applications.

Ni/Al2O3 catalysts for CO2 methanation: Effect of silica and nickel loading

Samples containing from 1 to 33 wt.% of NiO on silica and alumina doped with silica (1 and 20 wt.% silica in the support) have been prepared and characterized by BET, XRD, FT-IR, UV–vis–NIR, FE-SEM, EDXS, and TPR techniques. Catalysts have been pre-reduced in situ before catalytic experiments and data have been compared with Ni/Al2O3 reference sample. Characterization results showed that SiO2 support has a low Ni dispersion ability mainly producing segregated NiO particles and a small amount of dispersed Ni2+ in exchange sites. Instead, for the Si-doped alumina a “surface spinel monolayer phase” is formed by increasing Ni loading and, only when the support surface is completely covered by this layer, NiO is formed. Moreover, H2-TPR results indicated that NiO particles are more easily reduced compared to Ni species. Low loading Ni/SiO2 catalysts show high selectivity and moderate activity for RWGS (reverse Water Gas Shift) reaction, likely mainly due to nickel species dispersed in silica exchange sites, as evidenced by visible spectroscopy. High loading Ni/SiO2 catalysts show both methanation and RWGS but evident short-term deactivation for methanation, attributed to large, segregated Ni metal particles, covered by a carbon veil. Ni on alumina -rich carriers, where nickel disperses forming a surface spinel phase, show high activity and selectivity for methanation, and short-term catalyst stability as well. This activity is attributed to small nickel clusters or metal particles interacting with alumina, formed upon reaction. The addition of SiO2 in Al2O3 support decreases the activity of Ni catalysts in CO2 methanation, because it reduces the ability of the support to disperse nickel in form of the surface spinel phase, thus reducing the amount of Ni clusters in the reduced catalysts.

Visualising Co nanoparticle aggregation and encapsulation in Co/TiO2 catalysts and its mitigation through surfactant residues

Due to the reducible nature of TiO2, the encapsulation of cobalt nanoparticles (CoNPs) by reduced TiO2-x is often reported to decrease their catalytic performance in reactions such as Fisher-Tropsch synthesis (FTS). Here, we show using HAADF-STEM imaging and electron energy loss spectroscopy (EELS) that a residual C12E4 surfactant used to prepare the CoNPs, remains on the surface of a TiO2 rutile support, preventing the formation of Ti3+/Ti2+ oxides and therefore TiO2-x migration. Furthermore, the presence of these surfactant residues prevents the coalescence and aggregation of CoNPs during catalyst preparation, maintaining the dispersion of CoNPs. As such, using C12E4 in the preparation of Co/TiO2 can be considered beneficial for producing a catalyst with a greater number of active Co species.

Magnetic bentonite decorated with Pd nanoparticles and cross-linked polyvinyl pyridine as an efficient nanocatalyst for Suzuki coupling and 4-Nitrophenol reduction reactions

This study reports the preparation of a novel type of support based on magnetically recyclable bentonite functionalized with divinylbenzene-polyvinyl pyridine (PVP-DVB) for Pd (II) nanocatalyst by a simple cost-effective method. Firstly, the conventional co-precipitation method synthesized Fe3O4 nanoparticles (NPs) onto bentonite sheets. Then the prepared magnetic support surface was functionalized by divinylbenzene-polyvinyl pyridine (PVP-DVB) to create a cross-linked polymer with a high coordination ability with palladium. Repeated nitrogen units in the PVP-DVB polymer chain increase the number of Pd bonds and thus lead to higher performance of the nanocatalyst. Finally, the palladium NPs were simultaneously synthesized and immobilized under mild conditions. The synthesized nanocatalyst was characterized by several methods such as scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometer, inductively coupled plasma mass spectrometry and thermogravimetric analysis. The efficiency of synthesized heterogeneous nanocatalyst was investigated in Suzuki–Miyaura cross-coupling reactions between a range of aryl halides (X = Cl, Br, I) with phenylboronic acid and in the reduction of 4-nitrophenol (4-NP). Moreover, the synthesized nanocatalyst could be easily recovered and reused several times with an efficiency greater than 90%.

Factors Influencing the Accuracy of Guided Surgery: An In Vitro Trial.

Purpose: To examine how the accuracy (linear and angular deviation) of implants placed using computer-guided surgery varies in relation to the type of surgical technique (fully guided, half-guided, vs freehand implant placement), bone density (type D1 to D4 bone), and type of support surface (tooth- vs mucosa-supported). Materials and Methods: A total of 32 mandible models were produced (16 partially edentulous and 16 edentulous) using acrylic resin, each calibrated to a different bone density (D1 to D4). Four implants planned using Mguide software were placed in each acrylic resin mandible. A total of 128 implants were placed, distributed according to bone density (D1 to D4, n = 32), the degree of intervention in the surgery (fully guided [FG] = 80, half-guided [HG] = 32, and freehand surgery [F] = 16), and the type of support surface (tooth-supported: n = 64 and mucosa-supported: n = 64). To determine the linear, vertical, and angular deviations between the planned three-dimensional position and the actual position of the implants, the linear and angular difference between them was calculated, with the analysis performed through preoperative and postoperative CBCT scans. The effect was analyzed using parametric tests and linear regression models. Results: All parameters of linear and angular discrepancy in the various regions analyzed (neck, body, and apex) were primarily influenced by the technique and, to a lesser extent, by the bone type, although both variables were predictive and highly significant. These discrepancies tend to increase in completely edentulous models. The regression models show that linear deviations increase by between 630.2 μm at neck level in the buccolingual direction and 836.7 μm at apex level in the mesiodistal direction when comparing the FG and HG techniques. This increase is accumulative when comparing the HG and F techniques. Regarding the effect of bone density, the regression models found that linear discrepancies increase by between 132.6 μm in the axial direction and 199.0 μm at the apex of the implant in the buccolingual direction with each reduction in bone density (D1 to D4). Conclusion: According to this in vitro study, the highest implant placement predictability is found among dentate models with high bone density and a fully guided surgical technique.

Towards 3D printing of lipids - The impact of surface polarity on lipid assembly under spatial confinement.

Molecular dynamics (MD) simulations in the MARTINI model are used to study the assembly of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) molecules under spatial confinement, such as during solvent evaporation from ultrasmall (femtoliter quantity) droplets. The impact of surface polarity on molecular assembly is discussed in detail. Our results reveal that solvent evaporation gives rise to the formation of well-defined stacks of lipid bilayers in a smectic alignment. These smectic mesophases form on both polar and nonpolar surfaces but with a notable distinction. On polar surfaces, the director of the stack is oriented perpendicular to the support surface. By contrast, the stacks orient at an angle on the nonpolar surfaces. The packing of head groups on surfaces and lipid molecular mobility exhibits significant differences as surface polarity changes. The role of glycerol in the assembly and stability is also revealed. The insights revealed from the simulation have a significant impact on additive manufacturing, biomaterials, model membranes, and engineering protocells. For example, POPC assemblies via evaporation of ultrasmall droplets were produced and characterized. The trends compare well with the bilayer stack models. The surface polarity influences the local morphology and structures at the interfaces, which could be rationalized via the molecule-surface interactions observed from simulations.

QCM‐D Study of the Formation of Solid‐Supported Artificial Lipid Membranes: State‐of‐the‐Art, Recent Advances, and Perspectives

Solid‐supported lipid bilayers (SLBs) are excellent platforms for studying the biophysical properties of cell membranes. Among the existing approaches used to form SLBs, vesicle fusion and rupture onto solid supports are most commonly employed owing to their straightforward procedure. The current understanding of the mechanisms behind this approach has greatly benefited from the use of surface‐sensitive techniques, especially quartz crystal microbalance with dissipation monitoring (QCM‐D) in combination with other analytical techniques, such as atomic force microscopy (AFM) or localized surface plasmon resonance (LSPR). Herein, an overview of the pathways of vesicle adsorption and rupture under various experimental conditions is provided. Examples including recent findings of how the variation of the properties of lipid vesicles (size, charge), aqueous buffer (pH, ionic strength, osmotic pressure), and solid support (surface energy) affect the pathway mechanism of adsorption and rupture are provided. Recent reports on poorly understood properties such as surface roughness and topography are provided, together with the need for further studies relevant to biomimetic and sensing purposes.