Ratio Of Surface Area Research Articles

Removal of per- and polyfluoroalkyl substances from wastewater via aerosol capture

The widespread use of per- and polyfluoroalkyl substances (PFAS)-containing products in numerous commercial and industrial applications has resulted in their occurrence in wastewater treatment plants (WWTPs). Herein, proof-of-concept bench-scale experiments were performed to measure the extent to which PFAS could be removed from a WWTP if aerosols generated during aeration were captured. Experiments were designed to mimic the aeration rate:water volume ratio, the water volume:surface area ratio, and aeration bubble size applicable to the full-scale aeration vessel. Results showed that substantial (75%) removal of perfluorooctane sulfonate (PFOS) was observed under these operating conditions in the bench-scale system; up to 97% PFOS removal was observed if the aeration rate was increased 3-fold. PFAS removal generally increased with increasing aerosol capture and with increasing PFAS surface activity. Analysis of semi-quantified PFAS showed that the semi-quantified PFAS accounted for approximately 93% of the identified PFAS in the raw wastewater, dominated largely by the presence of 2:2 fluorotelomer carboxylic acid (2:2 FTCA). This preliminary study suggests that aerosol capture in aeration basins has potential for mitigating PFAS in WWTPs. Further testing is needed to assess the feasibility of this approach at the field scale.

Structure and Microchannel Catalytic Bed Performance of Silver Thin Films Prepared by Electroplating

The morphology of catalysts in microchannels plays a crucial role in the orbital maneuvering and networking applications of micro/nano satellites using hydrogen peroxide as a unit propellant. In this paper, a microfluidic reaction chip was designed and fabricated to detect the reaction rate of the catalytic decomposition of hydrogen peroxide solution by a microchannel catalytic bed. In addition, a silver thin film prepared by constant-current electroplating was used as a substrate for the microchannel catalyst. The results show that the ratio of surface area to area of silver film and the average particle size of silver particles have a significant positive correlation on the reaction rate of catalytic decomposition, while the thickness, silver content, and surface roughness of the silver film have no significant effect on the reaction rate of catalytic decomposition. The catalytic performance of the microchannel catalytic bed of silver thin film is greatly influenced by the conditions of electroplating, namely, the electroplating temperature (T), time (t), and current (I). And when I = 0.3 mA, t = 180 s, and T = 60 °C, the microchannel catalytic bed of the silver film prepared by electroplating reaches the optimal reaction rate for the catalytic decomposition of hydrogen peroxide solution. This study has the best process parameters for the design and optimization of heterogeneous catalysts applied to microfluidic reactors.

Determination of the embryotoxic effects of propofol injected into eggs on the cerebellum and spinal cord using histologic methods: an animal study.

This study aims to determine the possible embryotoxic effects of propofol on the cerebellum and spinal cord using fertile chicken eggs. A total of 430 fertile eggs were divided into 5 groups: control, saline, 2.5 mg.kg-1, 12.5 mg.kg-1, and 37.5 mg.kg-1 propofol. Injections were made immediately before incubation via the air chamber. On the 15th, 18th, and 21st day of incubation, 6 embryos from each group were evaluated. Serial paraffin sections taken from the cerebellum and spinal cord were stained with hematoxylin-eosin, Kluver-Barrera, toluidine blue, and periodic acid-Schiff's reaction. The outer granular layer and total cortex thickness were measured, and the linear density of the Purkinje cells was determined. The ratios of the substantia grisea surface area to the total surface area of the spinal cord were calculated. The transverse and longitudinal diameters of the canalis centralis were also assessed. No structural malformation was observed in any embryos examined macroscopically. No significant difference was observed between the groups in terms of development and histologic organization of the cerebellum and spinal cord. However, on the 15th, 18th, and 21st day, the outer granular layer (p < 0.001 for all days) and the total cortex thickness (p < 0.01, p < 0.001, and p < 0.001, respectively) decreased significantly in different propofol dose groups in varying degrees in the cerebellum. Similarly, in the spinal cord, there were significant changes in the ratios of the substantia grisea surface area to the total surface area (p < 0.01 and p < 0.001, respectively). It was concluded that the in-ovo-administered propofol given immediately before incubation has adverse effects on the developing cerebellum and spinal cord. Therefore, it is important for anesthesiologists always to remain vigilant when treating female patients of childbearing age.

Two stages segmentation for Leaf Area Index estimation using digital cover photography.

Leaf Area Index (LAI) is the ratio of ground surface area covered by leaves. LAI plays a significant role in the structural characteristics of forest ecosystems. Therefore, an accurate estimation process is needed. One method for estimating LAI is using Digital Cover Photography. However, most applications for processing LAI using digital photos do not consider the brown color of plant parts. Previous research, which includes brown color as part of the calculation, potentially produced biased results by the increased pixel count from the original photo. This study aims to enhance the accuracy of LAI estimation. The proposed methods consider the brown color while minimizing errors. Image processing is carried out in two stages to separate leaves and non-leaf pixels by using the RGB color model for the first stage and applying the CIELAB color model in the second stage. Proposed methods and existing applications are evaluated against the actual LAI value obtained using Terrestrial Laser Scanning (TLS) as the ground truth. The results demonstrate that the proposed methods effectively identify non-leaf parts and exhibit the lowest error rates compared to other methods. In conclusion, this study provides alternative techniques to enhance the accuracy of LAI estimation in forest ecosystems.

Functionalized graphene-based materials for cementitious applications.

Graphene-based materials (GBM) are promising cementitious composite additives that can significantly improve the mechanical characteristics and durability of concrete due to their unique properties, such as high surface area and aspect ratio and excellent tensile strength, to name a few. To display their full potential, GBM have to be homogeneously dispersed into the aqueous environment of cement-based matrices. The present study addresses the issue of limited dispersibility in the aqueous media of GBM through the chemical functionalization of mono- and few-layer graphene structures with hydrophilic aryl sulfonate groups and shows that a series of mortar samples containing modified GBM exhibit increased flexural and compressive strength by up to 17% and 30%, respectively, compared to mortar references without additives.

A two-dimensional coordination polymer with high laccase-like activity for sensitive colorimetric detection of thiram.

In contrast to natural enzymes, nanozymes show promising advantages of low cost and high stability for analytical applications. The simple mix of L-phenylalanine (F) and Cu2+ produces two-dimensional nanosheets of a coordination polymer with a high surface area ratio and rich exposed active sites as a novel catalyst. As the mimetic of natural laccase, this nanozyme (F-Cu) can catalyze the oxidative coupling reaction of 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP) to produce a distinct red product, thus establishing an intuitive and simple method for the detection of thiram. In the range of 0-7.5 μM, the absorbance intensity was linearly related to the concentration of thiram, and the detection limit was 0.0845 μM. The F-Cu nanozyme was successfully applied to the colorimetric detection of thiram in real samples.

Mineralogical characteristics influence the structure and pozzolanic reactivity of thermally and mechano-chemically activated meta-kaolinites

Mechano-chemical activation enhances early age (&lt;12 hours) pozzolanic reactivity of clays by transforming kaolinite to meta-kaolinite, reducing particle size, and potentially increasing the edge : basal surface area ratio of meta-kaolinite.

Sweetwood Lignin As a Promising Precursor Towards Multi-Functional Electrode Material

Currently, industrial development has led to a constant increase in demand for energy and sustainable energy resources, so there is an intensive search for a replacement for fossil fuels. The goal of this research is synthesis multi-functional electrode material using "Sweetwood" lignin (industrial by-product from sugars solutions for fuels, chemicals etc.) as a raw material via thermochemical activation with subsequent N-doping. Three-dimensional hierarchical micro- and mesoporous structures of activated carbon materials show promising results as an alternative PGM-free oxygen reduction catalysts for alkaline systems. The ORR activity of the synthesized carbon catalysts may be associated with the high percentage of pyridinic nitrogen, highly developed surface area, micro- and mesoporous ratio and balance, and lack of stacking defects of graphene layers. Furthermore, "Sweetwood" lignin carbon materials were assessed as electrode in supercapacitors. It was found that activation temperature plays a significant role on the specific capacitance which is additionally improved by doping of the carbon precursor with nitrogen. Acknowledgment The “Sustainably Produced Carbon Nanomaterials for Energy Applications (SuNaMa)” benefits from a 988000 € grant from Iceland, Liechtenstein, and Norway through the EEA Grants. The aim of the project is to develop innovative, high-performance, highly conductive, electrocatalytically active, durable, cost-effective, and high surface area nanocarbon materials. Project contract with the Research Council of Lithuania (LMTLT) No. is S-BMT-21-12 (LT08-2-LMT-K-01-055).

Blood Rheology and Hemodynamics.

Seminars in Thrombosis and Hemostasis (STH) celebrates 50 years of publishing in 2024. To celebrate this landmark event, STH is republishing some archival material. This article represents the most highly cited paper ever published in STH. The original abstract follows.Blood is a two-phase suspension of formed elements (i.e., red blood cells [RBCs], white blood cells [WBCs], platelets) suspended in an aqueous solution of organic molecules, proteins, and salts called plasma. The apparent viscosity of blood depends on the existing shear forces (i.e., blood behaves as a non-Newtonian fluid) and is determined by hematocrit, plasma viscosity, RBC aggregation, and the mechanical properties of RBCs. RBCs are highly deformable, and this physical property significantly contributes to aiding blood flow both under bulk flow conditions and in the microcirculation. The tendency of RBCs to undergo reversible aggregation is an important determinant of apparent viscosity because the size of RBC aggregates is inversely proportional to the magnitude of shear forces; the aggregates are dispersed with increasing shear forces, then reform under low-flow or static conditions. RBC aggregation also affects the in vivo fluidity of blood, especially in the low-shear regions of the circulatory system. Blood rheology has been reported to be altered in various physiopathological processes: (1) Alterations of hematocrit significantly contribute to hemorheological variations in diseases and in certain extreme physiological conditions; (2) RBC deformability is sensitive to local and general homeostasis, with RBC deformability affected by alterations of the properties and associations of membrane skeletal proteins, the ratio of RBC membrane surface area to cell volume, cell morphology, and cytoplasmic viscosity. Such alterations may result from genetic disorders or may be induced by such factors as abnormal local tissue metabolism, oxidant stress, and activated leukocytes; and (3) RBC aggregation is mainly determined by plasma protein composition and surface properties of RBCs, with increased plasma concentrations of acute phase reactants in inflammatory disorders a common cause of increased RBC aggregation. In addition, RBC aggregation tendency can be modified by alterations of RBC surface properties because of RBC in vivo aging, oxygen-free radicals, or proteolytic enzymes. Impairment of blood fluidity may significantly affect tissue perfusion and result in functional deteriorations, especially if disease processes also disturb vascular properties.

The effect of cathodic surface areas on galvanic interactions between grinding media, chalcocite and pyrite and subsequent mineral flotation

Sulphide mineral processing often involves grinding media and a number of types of sulphide minerals at various ratios of feed grades, but conventional studies on galvanic interactions for sulphide mineral processing often looked into dual-phase galvanic contacts with an equal surface area of anode and cathode. For the first time, this study investigated the galvanic interaction of a tri-phase galvanic system (GM-Cc-Py) consisting of grinding media, chalcocite and pyrite with different surface area ratios of pyrite to chalcocite (Py/Cc) to reflect the practical nature. The electrochemical studies found that chalcocite acted as a cathode in the galvanic system in the absence of pyrite, but it was switched to an anode after the addition of pyrite at Py/Cc = 1. An increase in pyrite surface area not only further anodised grinding media and chalcocite, but also increased the galvanic interaction and the oxidation of anodic materials. This nature of galvanic interactions was found to impact the pulp chemistry after grinding and also the mineral flotation behaviour. A greater pyrite surface area caused a more reducing pulp condition and higher chalcocite oxidation, both promoting copper activation on pyrite and then pyrite flotation. This study identified a high amount of pyrite recovered in copper mineral flotation at a high pyrite feed grade and suggested solving this problem by altering the cathodic role of pyrite.

Electrochemical determination of the procyanidins in peanut skin using a carbon nanotube electrode.

We demonstrated the electrochemical detection of procyanidins in peanut skin, which is often a waste product of the food industry, using a carbon nanotube electrode. Procyanidins, the main ingredients of peanut skin, are oligomers of catechin or epicatechin; therefore, they have various forms such as dimers, trimers, and a different number of linkages between monomers. Quantification using traditional high-performance liquid chromatography-mass spectroscopy (HPLC-MS) is tedious, because many peaks can be traced. The use of CNT electrodes for procyanidin sensing is promising, because CNT's properties, such as high conductivity, catalytic ability, and special geometry (high ratio of surface area to volume), enable common and specific profiles of the cyclic voltammograms (CVs) of procyanidins. Furthermore, the intensity of the anodic peaks (+ 0.32V) due to the oxidation of catechol groups is proportional to the concentration of procyanidin (linear rang: 2.8-88mgL-1, sensitivity: 1.4mAmg-1Lcm-2), and does not depend on the type of procyanidin. The amount of procyanidins in the peanut skin estimated by CV was similar to that estimated by HPLC-MS. This study may contribute to accelerating the utilization of peanut skin for animal food, drugs, and supplementation.

Insitu assembly of Fe3O4@FeNi3 spherical mesoporous nanoparticles embedded on 2D reduced graphene oxide (RGO) layers as protective barrier for EMI pollution

Electromagnetic interference (EMI) is a major issue due to the increased use of electronic devices operating in the gigahertz frequency range. Consequently, to reduce electromagnetic pollution, materials with considerable magnetic and dielectric loss can be used for the attenuation of electromagnetic waves. In this paper, Fe3O4 FeNi3 spherical mesoporous nanoparticles embedded on reduced graphene oxide (RGO) layers have been synthesized using the hydrothermal reduction method. The specific surface area of Fe3O4@FeNi3/RGO nanocomposite was 67.4 m2/g with a pore size diameter of 3.4 nm (i.e., mesoporous range). Fe3O4@FeNi3/RGO nanocomposites show an enhanced absorption dominant shielding effectiveness (SE) value of 46.49 dB as compared to its binary counterpart Fe3O4@FeNi3, having SE value of 25.21 dB. The synthesized Fe3O4@FeNi3/RGO nanocomposite of thickness 1.42 mm has SER of ∼10.32 dB and SEA of ∼36.15 dB at 15 GHz. Furthermore, it is observed that shielding efficiency increases with increasing reduced graphene oxide (RGO) content in Fe3O4@FeNi3, which is owing to an excellent interconnected network between RGO and Fe3O4@FeNi3. The RGO sheets can create a comprehensive conductive network for the distribution of charges and can enhance dielectric loss because of the layered structure, greater specific surface area and large aspect ratio. Additionally, the mesoporous Fe3O4@FeNi3 hybrid embellished on the surface of RGO may be employed as a multi-pole polarisation centre, enhancing the electronic and space charge polarization of the composites, which is helpful for strong EM wave absorption. It was believed that these nanocomposites would pave the way for the development of RGO-based mesoporous nanocomposites as broadband, lightweight and effective shielding material for practical applications.

Cuttlefish-Inspired Photo-Responsive Antibacterial Microparticles with Natural Melanin Nanoparticles Spray.

Topical antibiotics can be utilized to treat periodontitis, while their delivery stratagems with controlled release and long-lasting bactericidal inhibition are yet challenging. Herein, inspired by the defensive behavior of cuttlefish expelling ink, this work develops innovative thermal-responsive melanin-integrated porous microparticles (MPs) through microfluidic synthesis for periodontitis treatment. These MPs are composed of melanin nanoparticles (NPs), poly(N-isopropylacrylamide) (PNIPAM), and agarose. Benefiting from the excellent biocompatibility and large surface area ratio of MPs, they can deliver abundant melanin NPs. Under near-infrared irradiation, the melanin NPs can convert photo energy into thermal energy. This leads to agarose melting and subsequent shrinkage of the microspheres induced by pNIPAM, thereby facilitating the release of melanin NPs. In addition, the released melanin NPs can serve as a highly effective photothermal agent, displaying potent antibacterial activity against porphyromonas gingivalis and possessing natural anti-inflammatory properties. These unique characteristics are further demonstrated through in vivo experiments, showing the antibacterial effects in the treatment of infected wounds and periodontitis. Therefore, the catfish-inspired photo-responsive antibacterial MPs with controlled-release drug delivery hold tremendous potential in clinical antibacterial applications.

Morphological and Optical changes with dopant concentration of Bi2O3 in Al2Bi2O6-δ nano-particulates

In present scenario, technologies based on nanomaterials applications are taken at the top priorties because of their advanced properties. The materials have colourful size-dependent properties at nanoscale because of its significant ratio of surface area to volume. In this study, different compositions of alumina nanocrystalline materials incorporated with Bi2O3 (5%,10%,20%) were prepared by using micro wave treated (at 100°C for 15 minutes) chemical route techniques at calcination temperature of 600°C for a duration of 2 hours resulted in uniform sized nano-particulates were obtained. The ultrafine powder samples were analyzed by using techniques including UV-Vis- NIR spectrum, XRD, HRTEM, FTIR & FESEM etc. The XRD data reveals that the crystallite size of the nano crystals increased from 28.9nm (Pure alumina), 30.1nm (5% Bi2O3doped), 36.8nm (10% Bi2O3doped), 41.21 nm (20% Bi2O3doped) respectively and indicates increasing trend with dopant concentration for fixed calcination temperature of 600°C for a duration of 2 hours. The IR spectrum were deployed to examine the functional group existing in samples and concluded that corresponding IR alps were found at different wave numbers for each dopant concentration, with multiple alps/peaks attributed at 3300cm−1and at 1600cm−1were due to-OH group’s vibration mode and water content in the surroundings respectively. The alp at 1300 cm−1 was related to the adsorption of NO2 and CO2 in the surroundings and nitrate salt used for preparing the samples, while other alps at 582 cm−1 (O-Al-O) and 512 cm− 1(O-Bi-O) were related to various metal oxide vibrations. In UV-VIS spectroscopy, the tauc plot revealed that the energy band gap was 1.67 eV, 1.85eV, 2.72eV and 2.89 eV respectively. The microscopy through field emission of scanning of electron (FESEM) image displayed truncated spherical particles that were agglomerated in nature. The HRTEM findings are consistent with the results obtained from XRD data and FESEM.

Effect of donor-recipient size mismatch on long-term graft survival in pediatric kidney transplantation: a multicenter cohort study.

Donor-recipient size mismatching is commonly occurs in pediatric kidney transplantation (KT). However, its effect on graft survival remains unknown. This study aimed to determine the effect of donor-recipient size mismatch on the long-term survival rate of transplant kidneys in pediatric KT. A total of 241 pediatric patients who received KT were enrolled. The medical records of all patients were retrospectively reviewed, and the correlation between donor-recipient size mismatch and graft function and long-term graft outcome was analyzed according to donor-recipient size mismatch. Recipients and donors' mean body weight at the time of KT were 34.31 ± 16.85 and 56.53 ± 16.73 kg, respectively. The mean follow-up duration was 96.49 ± 52.98 months. A significant positive correlation was observed between donor-recipient body weight ratio (DRBWR) or donor-recipient body surface area ratio (DRBSR) and graft function until 1 year after KT. However, this correlation could not be confirmed at the last follow-up. The results of long-term survival analysis using Fine and Gray's subdistribution hazard model showed no significant difference of the survival rate of the transplant kidney according to DRBWR or DRBSR. Donor-recipient size mismatch in pediatric KT is not an important factor in determining the long-term prognosis of transplant kidneys.

Impact of gold ion irradiation on the initial alteration rate of the International Simple Glass

This study addresses the impact of 7 MeV Au irradiation on the initial alteration rate of International Simple Glass (ISG), considered as a reference for nuclear glasses. This irradiation scenario simulates the effect of nuclear collisions of the recoil nuclei of α decays. In order to study the very first moments of glass alteration, non-irradiated and Au-ion irradiated ISG glass monoliths were altered in pure water at 90 °C, pH 9 and with a ratio of glass surface area to solution volume of 0.01 cm−1. Glass alteration was monitored by measuring the releases of the glass elements in solution by UV–visible spectrophotometry and Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). Under these alteration conditions, the releases of the elements in solution are congruent. The initial alteration rate was found to be (2.0 ± 0.8) times higher for the irradiated glass monoliths than for non-irradiated samples.

Abstract 17910: Is Implantation of a Larger Edwards Sapien Transcatheter Pulmonary Valve Associated With Early Valve Failure? A Different Type of Patient-Prosthesis Mismatch

Introduction: Transcatheter pulmonary valve replacement (TPVR) is an alternative option to address failing native and bioprosthetic pulmonary valves (BPV). TPVR has expanded to implantation in native right ventricular outflow tracts (nRVOT) and progressively smaller patients. We aim to define the relationship between valve-to-patient size ratio and early development of pulmonary insufficiency (PI). Methods: This single-center retrospective cohort study identified patients who underwent TPVR with a Sapien valve between 2014 and 2021. We collected demographic, anatomic, and pre- and post-TPVR echo data. Echo data were collected at four post-TPVR time points: prior to discharge, short-term (1-9 months), mid-term (9-18 months), and most recent study. The primary outcome was development of moderate or severe PI by mid-term follow-up. Valve size-to-body surface area (BSA) ratio was evaluated for correlation with the development of moderate or severe PI. Results: The cohort consisted of 187 patients; 79 (42.2%) underwent TPVR within the nRVOT (Table). Compared to patients with TPVR in a conduit or BPV, patients with a nRVOT were younger, had lower weight, and lower BSA. Moderate or severe PI post-TPVR was more common in patients in the nRVOT group (P-value &lt; 0.001), occurring in 9 (11.5%) by mid-term follow-up, compared to 2 (1.9%) in a conduit or BPV. In the subset of patients with TPVR within the nRVOT, the development of moderate or severe PI was associated with a larger valve size-BSA ratio (OR=1.13, 95% CI: 1.03, 1.26, P-value=0.012). Conclusions: Development of moderate or severe PI following TPVR with a Sapien valve was rare in this cohort. Patients receiving a Sapien TPVR within the nRVOT with a large valve size-to-BSA ratio were more likely to develop early PI. The increased risk of early valve failure in these patients should inform counseling regarding expected longevity of the valve and may guide valve choice as more transcatheter valve options become available.

Numerical Investigations on Enhancement of Pool Boiling Heat Transfer on a Mixed Wettability Surface Employing Lattice Boltzmann Method

Abstract In this paper, a systematic numerical study of pool boiling heat transfer on a mixed wettability heated surface is done using the lattice Boltzmann method (LBM) with a multiple relaxation time (MRT)-based collision operator. The effect of the design parameters, viz, size of the hydrophobic patch (D), spacing between hydrophobic patches (L), number of hydrophobic patches (N), and uneven-sized patches, on pool boiling was studied and results are explained through detailed analysis of bubble nucleation, growth, coalescence, and departure from the heated surface. The results show that mixed wettability surfaces with strategically sized and positioned hydrophobic patches on a hydrophilic surface can result in high heat flux for pool boiling across the entire range of surface superheat or Jacob number (Ja) by combining the advantages of hydrophobic surface in nucleate boiling and hydrophilic surface in transition and film boiling. Further, the mixed wettability surface can delay the onset of film boiling compared to a pure or superhydrophilic surface thereby resulting in higher critical heat flux (CHF). A hydrophobic to total surface area ratio of 30–40% was found to be optimal for all ranges of surface superheat or Jacob number (Ja), which agrees well with the experimental result of 38.46% reported by Motezakker et al. (2019, “Optimum Ratio of Hydrophobic to Hydrophilic Areas of Biphilic Surfaces in Thermal Fluid Systems Involving Boiling,” Int. J. Heat Mass Transfer, 135, pp. 164–174).

Study on the energy-saving effects of radiative material properties and material coating ratios in residential neighborhoods with different morphologies

The application of radiative materials (cool or super cool) on building surfaces has the potential to reduce summer energy consumption in buildings significantly. There is insufficient conclusive evidence regarding the energy-saving effects of cool and super cool materials applied to building façades. Therefore, in order to derive the effect of the material coating ratio of cool and super cool materials on the building façade on the building energy consumption, 106 schemes with varying material coating ratios were investigated by using EnergyPlus. The research findings indicate that applying cool and super cool materials to the building façade of high floors contributes more to energy savings in summer compared to middle and low floors. From an annual perspective, for residential neighborhoods of high-rise buildings, each floor using cool or super cool materials has an average annual energy saving rate (ESR) of 0.07–0.09%. The annual ESR can reach 1.9–2.4% when the façades of a 28-story building are entirely coated with cool and super cool materials. Additionally, point-type buildings have a higher energy-saving rate per material area than slab-type buildings. The energy-saving rate is not correlated with building density but is significantly related to floor area ratio, surface area ratio, and sky view factor. The conclusions of this study can provide a reference for the energy-saving retrofit of residential buildings in Nanjing.

Manufacturing of Poly-DL-Lactic Acid Nanosheets and Evaluation of Tribological Characteristics between Nanosheet Surfaces and Fingers

Attention is focused on ultra-thin polymer films (nanosheets) that have high flexibility and adhesiveness and their thickness can be controlled to several tens of nanometers. These nanosheets can be neatly attached to surfaces with complex irregularities without the use of adhesives. Therefore, the ratio of surface area to thickness is very large, and we believe that the relationship with friction is very significant in nanosheet technology for biomedical applications such as wearable devices and wound dressings. The purpose of this study is to investigate the contact mechanism of nanosheets with human fingertip skin in terms of friction coefficient by using the microgravure printing method, which enables thin film coating. From the results of film thickness measurements, it was found that nanosheets of any thickness can be fabricated by the microgravure printing method. The friction measurement results showed that the coefficient of friction of the nanosheets decreased except for vertical loads above Fz=2N. The coefficient of friction increased as the contact area increased. It was found to increase with increasing vertical load under the immersion in water conditions, and conversely, it decreased under the drying condition except for the high normal load of 2N. Furthermore, the coefficient of friction was found to increase with increasing nanosheet thickness. Observation of wear traces showed that when the vertical load was sufficiently high (Fz = 2 N), wear traces containing oily traces such as sebum and sweat appeared on the nanosheet surface. This is thought to function as a lubricant. Polymer nanosheets are a new material, and there have been few studies on friction with this material. Research on friction is very important because polymer nanosheets are expected to be applied to wound dressings and displays of electronic devices.