Roughness Area Research Articles

Characterization and Evaluation of Human Health Risk of Heavy Metals in Tin Mine Tailings in Selected Area of Plateau State, Nigeria

Tin mining tailings are unprocessed waste materials that overlie an ore which are displaced during mining activities. This research work is aimed at characterizing and evaluating the human health risk of heavy metals in tin mine tailings in Zabot (S3) and Tafan (S4) districts in Barkin Ladi Local Government Area of Plateau State, Nigeria. The samples were characterized using EDX-XRF and SEM. The concentrations of seven heavy metals (Pb, Cr, As, Ni, Cd, Cu and Zn) were determined in S3 and S4. The results showed that Cr, Ni, Cd, Cu and Zn were within the USEPA permissible limits, except for Pb and As with range of (270-300) mg/kg and (40-70) mg/kg respectively for both mining and control sites of S3 and S4. The SEM results revealed small particles size with fine porous structure, and rough areas with varying sizes and pores distributed over the surface for S3 and S4 respectively. Results of the risk assessment showed that the hazard quotient HQ and HI values were greater than 1 indicating high risk. The Carcinogenic and non-carcinogenic risks associated with Pb, Zn, Cd, Cr, Ni and As were evaluated for S3 and S4 for the three exposure pathway and it was found that the mining sites pose more risk than the control and the children were more exposed than the adults. The carcinogenicity of these samples were due to the high hazard quotient for ingestion and dermal exposure pathway. The R total results for As, Cr, Pb and Ni for mining site S3 were found to be (1.39 × 102 , 2.02 × 10-7 , 3.30 × 103 and 8.17 × 10-8 ), and control site (3.42 × 103 , 2.64 × 10-5 , 38.30 × 101 , 6.90 × 10-8 ) for As, Cr, Pb and Ni respectively. From the R total results As and Pb were more than the acceptable threshold, while Cr and Ni were below the threshold of 1 × 10-4 . For the mining site S4, the R total were found to be (5.70 × 102 , 1.82 × 10-7 , 3.63 × 104 and 9.64 × 10-9 ),and the control (1.16 × 103 , 1.71 × 10-7 , 31.1 × 102 and 1.51 × 10-8 ) for As, Cr, Pb and Ni respectively. From the results of the mining and control sites, As and Pb R total were higher than the acceptable threshold, while Cr and Ni were below the threshold of 1 × 10-4 .

Life and Flaking Failure of 13Cr-2Ni-2Mo and SUS440C Stainless Steel Bearings in Water

The rolling contact fatigue (RCF) tests of 13Cr-2Ni-2Mo and SUS440C stainless steels were carried out in water. Their groove surfaces and the flaking failures were observed. Some hair cracks, wear and high roughness area were found. While the flaking depth of SUS440C was shallower than that of 13Cr-2Ni-2Mo stainless steel, the RCF life of the latter was longer than the former one. The flaking depth did not influence the RCF life.

FRESH STATE AND MECHANICAL PROPERTIES OF ULTRA-LIGHTWEIGHT FOAMED CONCRETE INCORPORATING ALKALI TREATED BANANA FIBRE

For a Lightweight Foamed Concrete (LFC) to efficiently function as an energy-saving building material, its self-weight (density) should be reduced. However, the problem associated with a reduced density is a decline in strength. To improve the mechanical properties of LFC, this research attempts to integrate banana fibre into LFC composite with a focus on fresh and harden state properties. An Ultra-Lightweight Foamed Concrete (ULFC) with a density of 600 kg/m3 was produced with the inclusion of treated and untreated banana fibres. The volume fractions of banana fibre added into LFC were 0.00% (control specimen), 0.25%, 0.35%, 0.45% and 0.55%. In addition, an optimised batch mix of ULFC reinforced with 0.35% untreated banana fibre was produced. The batches were tested for rheological, physical, and mechanical properties. Findings reveal that the workability of ULFC composites decrease with increase in fibre addition. The compressive, flexural, and tensile strengths of the alkali-treated composites were higher than the untreated banana fibre composite. SEM micrograph reveals that defibrillation of bundle fibrils due to cleaning the surface amorphous hemicellulose, lignin and pectin of the alkali-treated fibre, leads to rough surfaces and increase surface area resulting in better interfacial adhesion of the fibre with cement matrix.

Techniques used in Evaluating Performance of Solar Air Heater (SAH) Comprised of Winglet Type Roughness- A Review

There are multiple resource of energies but if we talk about renewable energy then solar energy is one of the renewable energy which is in demand because it is feasible and cheap. Flat - plate solar air heaters (SAHs) are simplistic and stylish, and their heating pathway of implementation requires care and support. increasing Room temperature, elimination of moist from farm commodities, increasing temperature of industrialized goods, hardening of wood or timber, and other uses for SAHs are frequent. well there are several issues in SAH, but the biggest issues with the SAH is its ineffectiveness, which is caused by atmosphere's lower heat transferring ability. We present introduces on the work performed by a lot of scientists to boost the effectiveness of solar air heaters (SAHs) with various kinds of roughness area in this research article.

Tuning the Dielectric Constant and Surface Engineering of a BaTiO3/Porous PDMS Composite Film for Enhanced Triboelectric Nanogenerator Output Performance.

In this work, synergistic effects derived from surface engineering and dielectric property tuning were exploited to enhance the output performance of a triboelectric nanogenerator (TENG) based on an inorganic/porous PDMS composite in a contact–separation mode. BaTiO3 (BT)/porous PDMS films with different BT weight ratios were fabricated and evaluated for triboelectric nanogenerator (TENG) application. Maximum output signals of ca. 2500 V, 150 μA, and a power density of 1.2 W m–2 are achieved from the TENG containing 7 wt % BT, which is the best compromise in terms of surface roughness, dielectric constant, and surface contact area as evidenced by SEM and AFM studies. These electrical signals are 2 times higher than those observed for the TENG without BT. The 7BT/porous PDMS-based TENG also shows high stability without a significant loss of output voltage for at least 24 000 cycles. With this optimized TENG, more than 350 LEDs are lit up and a wireless transmitter is operated within 9 s. This work not only shows the promoting effects from porous surfaces and an optimized dielectric constant but also offers a rapid and template/waste-free fabrication process for porous PDMS composite films toward large-scale production.

Synthesis of MOF/MoS2 composite photocatalysts with enhanced photocatalytic performance for hydrogen evolution from water splitting

With the shortage of global fossil energy and the increasing crisis of environmental deterioration, hydrogen energy has become an environmentally benign alternative as a clean energy source. In most studies on photocatalytic hydrogen production, novel photocatalytic material has played an important role to enhance the hydrogen production rate. In this study, the optimal conditions for the synthesis of MoS2 were established through series of characterizations with 190 °C calcination temperature and 1 wt% PEG surfactant addition. The best conditions for synthesizing MOF include copper nitrate as the copper precursor, 30% ultrasonic amplitude, and 240 °C calcination temperature. After adding 1 wt% MOF in MOS2, a flower-like structure with small particle size, uniform distribution, regularity, and large surface pores, has been formed, where its unit is modified with many rough, porous, and high specific surface area octahedral structures. In addition, 1MOF/MOS2 has the most negative conduction band edge (−0.135 V), the smallest charge transfer resistance (Rct = 1.78 Ω), the largest photo current (11.1 mA/cm2), the lowest PL spectral peak intensity, and excellent photocatalytic stability. The above morphological features and optical properties can significantly form more active sites, enhance the electron transfer rate, and inhibit the electron-hole recombination, thus making the MOF/MOS2 composite photocatalyst achieve the maximum hydrogen production capacity (626.3 μmol g−1 h−1).

Development and validation of an analytical method for tensile strength determination of fibrous bulk solids

The increasing significance of products consisting of elongated particles or fibres along with a lack of understanding flow properties of fibrous bulk solids in processes urge for appropriate test procedures.Therefore, a tensile tester was designed with respect to the special needs in terms of test techniques of those bulk solids. The procedure of tensile strength determination was tested with regard to several possible influencing factors. Following from that, the manner of filling and filling height were identified to have the greatest influence on results. Furthermore, it is shown that the developed load system is capable of improving the repeatability of test results for fibrous bulk solids.Based on the derived standard procedure, systematic tests were carried out on beech and spruce chips in three different fractions each as well as model materials such as polypropylene fibres and differently sized bunches of glass fibres. The biomass materials have been characterised by dynamic image analysis prior to and after experiments resulting in particle size and shape factor distributions. It is found that tensile strength is affected by particle shape, size, roughness and interparticle contact area.

Examining properties influencing infectious microbe associations with surfaces of four different thermoplastic radiation therapy masks

BackgroundPrevious testing revealed that four different microbes applied to face-only masks from Civco, Klarity Medical, Orfit, and Qfix demonstrated variation in the number recovered from each mask type after a 1-hour contact time. In all cases, the Orfit mask demonstrated the largest number of recovered microbes suggesting a preference by tested microbes to create associations with this mask type. MethodsThe current study evaluated three physiochemical features of these thermoplastic masks to determine why the Orfit mask encouraged greater microbial associations. Measurements including water contact angle (WCA), surface topography, and available contact area were determined for each mask type, where feasible. ResultsThe Orfit mask exhibited the greatest difference in each of the 3 evaluated characteristics. Overall, it showed decreased hydrophobicity, increased surface roughness, and increased surface contact area. The WCA of both Orfit (50.8°) and Klarity (95.6°) masks showed decreased hydrophobicity when compared to native PCL (129.97°). ConclusionThe Orfit mask's decreased hydrophobicity, increased roughness, and larger surface contact area appears to have contributed to its ability to support a larger number of microbe associations. The decreased hydrophobicity and altered topography of both Klarity and Orfit masks may have been due to their additional antimicrobial coatings.

Efficient Photocatalytic Degradation of Organic Pollutant in Wastewater by Electrospun Functionally Modified Polyacrylonitrile Nanofibers Membrane Anchoring TiO2 Nanostructured.

In this study, polyacrylonitrile (PAN_P) nanofibers (NFs) were fabricated by electrospinning. The PAN_P NFs membrane was functionalized with diethylenetriamine to prepare a functionalized polyacrylonitrile (PAN_F) NFs membrane. TiO2 nanoparticles (NPs) synthesized in the laboratory were anchored to the surface of the PAN_F NFs membrane by electrospray to prepare a TiO2 NPs coated NFs membrane (PAN_Coa). A second TiO2/PAN_P composite membrane (PAN_Co) was prepared by embedding TiO2 NPs into the PAN_P NFs by electrospinning. The membranes were characterized by microscopic, spectroscopic and X-ray techniques. Scanning electron micrographs (SEM) revealed smooth morphologies for PAN_P and PAN_F NFs membranes and a dense cloud of TiO2 NPs on the surface of PAN_Coa NFs membrane. The attenuated total reflectance in the infrared (ATR-IR) proved the addition of the new amine functionality to the chemical structure of PAN. Transmission electron microscope images (TEM) revealed spherical TiO2 NPs with sizes between 18 and 32 nm. X-ray powder diffraction (XRD) patterns and energy dispersive X-ray spectroscopy (EDX) confirmed the existence of the anatase phase of TiO2. Surface profilometry da-ta showed increased surface roughness for the PAN_F and PAN_Coa NFs membranes. The adsorption-desorption isotherms and hysteresis loops for all NFs membranes followed the IV -isotherm and the H3 -hysteresis loop, corresponding to mesoporous and slit pores, respectively. The photocatalytic activities of PAN_Coa and PAN_Co NFs membranes against methyl orange dye degradation were evaluated and compared with those of bare TiO2 NPs.The higher photocatalytic activity of PAN_Coa membrane (92%, 20 ppm) compared to (PAN_Co) NFs membrane (41.64%, 20 ppm) and bare TiO2 (49.60%, 20 ppm) was attributed to the synergy between adsorption, lower band gap, high surface roughness and surface area.

Application of the nonlinear optimisation in regional gravity field modelling using spherical radial base functions

The gravity field is a signature of the mass distribution and interior structure of the Earth, in addition to all its geodetic applications especially geoid determination and vertical datum unification. Determination of a regional gravity field model is an important subject and needs to be investigated and developed. Here, the spherical radial basis functions (SBFs) are applied in two scenarios for this purpose: interpolating the gravity anomalies and solving the fundamental equation of physical geodesy for geoid or disturbing potential determination, which has the possibility of being verified by the Global Navigation Satellite Systems (GNSS)/levelling data. Proper selections of the number of SBFs and optimal location of the applied SBFs are important factors to increase the accuracy of estimation. In this study, the gravity anomaly interpolation based on the SBFs is performed by Gauss-Newton optimisation with truncated singular value decomposition, and a Quasi-Newton method based on line search to solve the minimisation problems with a small number of iterations is developed. In order to solve the fundamental equation of physical geodesy by the SBFs, the truncated Newton optimisation is applied as the Hessian matrix of the objective function is not always positive definite. These two scenarios are applied on the terrestrial free-air gravity anomalies over the topographically rough area of Auvergne. The obtained accuracy for the interpolated gravity anomaly model is 1.7 mGal with the number of point-masses about 30% of the number of observations, and 1.5 mGal in the second scenario where the number of used kernels is also 30%. These accuracies are root mean square errors (RMSE) of the differences between predicted and observed gravity anomalies at check points. Moreover, utilising the optimal constructed model from the second scenario, the RMSE of 9 cm is achieved for the differences between the gravimetric height anomalies derived from the model and the geometric height anomalies from GNSS/levelling points.

Promoting highly dispersed Co3O4 nanoparticles onto polyethyne unraveling the catalytic mechanism with stable catalytic activity for oxygen evolution reaction: From fundamentals to applications

The solution to overcome the energy crisis in the globe with saving the environment from pollution and the community health, along with other applications of electrochemical for water splitting to get hydrogen and oxygen as a clean fuel. Likewise, the conducting polymers experience as stability over long time, or some time the breaking of conducting polymer chain is unavoidable with addition of polymer. For many reasons, we use noble metal co-catalysts in conjunction with semiconductors for improved hydrogen and oxygen gas production by the water splitting. The morphological characterization, & chemical composition of pristine & composite material studies with the help of different analytical techniques as like SEM, EDX, XRD, XPS & HRTEM. An outperform and active non-noble electrocatalyst for the oxygen evolution reaction which is a hotspot in the current research activities for oxygen & hydrogen production with zero carbon dioxide emission. Herein, we present an advanced material Co3O4/polyethyne for the first time to produce oxygen at a reasonable overpotential. The best oxygen evolution performance of Co3O4/polyethyne (20) providing the best performance at low overpotential 260 mV at 10 mAcm−2 the Tafel slope 64 mVdec−1, further strongly acceptable durability approximately for the 30 h & finally obtained charge transfer resistance value of 82.58 Ohms & greater capacitance 1.56 mF value for Co3O4. The key element in the success of newly developed catalyst is the greater amount of Co3O4 nanoparticles due to selective growth on polyethyne which has played a dominant role in oxygen production. It is because of the worth mentioning properties of polyethyne as a good electrical conductor, as efficient catalyst Co3O4 with more surface roughness and high surface area, which is strongly boosting the production of oxygen. The developed material can be applied in other competing fields such as lithium-ion batteries, solar cells, energy storage devices, and photochemical water splitting.

Influence of post-processing on very high cycle fatigue resistance of Inconel 718 obtained with laser powder bed fusion

The pore defects and surface roughness derived from additive manufacturing restrict applications in the production of ultra-long service time parts. Due to the high sensitivity of very high cycle fatigue (VHCF) resistance to defects, smaller defects may also become potential crack initiation sites. To remove these defects and consequently improve fatigue strength, three different post-processing routes, hot isostatic pressing (HIP, 1160 °C/1500 bar/3h ± 30 min), machining, and their combinations, are employed on samples in this research. Three-dimensional X-ray tomography (3D-XRT) shows that pores larger than 25 μm in diameter are mainly located in the “macropore-rich layer” with 300 μm thickness below the surface. HIP can effectively close the pores, but this does not translate into an increase in fatigue performance, which is attributed to the increased roughness. Machining with a certain depth can significantly reduce the surface roughness and remove the “macropore-rich layer.” Therefore, it can improve fatigue resistance. The co-effect of HIP and machining is confirmed to be the most effective solution to improve fatigue resistance. Taking the depth-width ratio of the micro-depression as the characteristic size of the surface roughness, it found that the fatigue life is closely related to the characteristic size of the micro depression. For the pore-induced fatigue failure, the fatigue resistance is related to the pore size and the location. The area of the crack initiation (rough area, abbreviation as RA) is introduced and Areapore/AreaRA is calculated to reflect the pore characterization including the size and location, and the ratio of the pore area to the RA area is found to be have a linear relationship to the fatigue life in single logarithmic coordinates.

Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock

Crystalline rock is one of the host rocks considered for a future deep geological repository for highly active radiotoxic nuclear waste. The safety assessment requires reliable information on the retention behavior of minor actinides. In this work, we applied various spatially resolved techniques to investigate the sorption of Curium onto crystalline rock (granite, gneiss) thin sections from Eibenstock, Germany and Bukov, Czech Republic. We combined Raman-microscopy, calibrated autoradiography and µTRLFS (micro-focus time-resolved fluorescence spectroscopy) with vertical scanning interferometry to study in situ the impact of mineralogy and surface roughness on Cm(III) uptake and molecular speciation on the surface. Heterogeneous sorption of Cm(III) on the surface depends primarily on the mineralogy. However, for the same mineral class sorption uptake and strength of Cm(III) increases with growing surface roughness around surface holes or grain boundaries. When competitive sorption between multiple mineral phases occurs, surface roughness becomes the major retention parameter on low sorption uptake minerals. In high surface roughness areas primarily Cm(III) inner-sphere sorption complexation and surface incorporation are prominent and in selected sites formation of stable Cm(III) ternary complexes is observed. Our molecular findings confirm that predictive radionuclide modelling should implement surface roughness as a key parameter in simulations.

Onychophagia: detailed clinical characteristics.

Onychophagia is a common disorder affecting 20% to 30% of the general population. It is defined as habitual nail biting and can cause various changes in the nail units. However, to date, there has been a paucity of data focusing on nail deformities related to onychophagia. This study was performed to investigate the clinical characteristics of onychophagia in Korea. This study included 53 patients with onychophagia who visited the Pusan National University Hospital (Busan and Yangsan) over a 10-year period (2011-2020). We retrospectively reviewed medical records and clinical and dermoscopic photographs. All 10 fingernails were affected in 37.7% of the patients. The left thumbnail was the most predominantly affected site (81.1%). Clinical findings showed that short nails with ragged distal borders were the most common presentation (100.0%), followed by generalized or patchy rough areas (50.9%), linear and pinpoint hemorrhage (32.1%), longitudinal melanonychia (30.2%), transverse groove (28.3%), brittleness (28.3%), macrolunula (24.5%), washboard nail (13.2%), and pterygium (3.8%). Of the patients, 88.7% had periungual complications, such as periungual exfoliation (77.4%), absent or ragged cuticle (52.8%), hyponychial hyperkeratosis (37.7%), and paronychia (15.1%). Although onychophagia is a common disorder, its clinical characteristics have not been reported in the literature. The results of this study may be helpful in managing patients with onychophagia.

Morphofunctional examination of the carpal bones of pygmy hippopotamus from Ayia Napa, Cyprus.

This study provides a complete morphological description and functional analysis of the carpal bones of the endemic pygmy hippopotamus Phanourios minor, derived from the Upper Pleistocene site of Ayia Napa. From this deposit, numerous skeletal remains of this fossil hippo have been collected, making the locality one of the richest in Cyprus. The carpal bones were compared with those of extant hippopotamuses, to determine the changes that occurred in the fossil hippo. Examination of the elements showed that Phanourios presented some important features that were common among the endemic fossil ungulates of the Mediterranean islands. The carpal bones display a proximal-distal compression due to shortening of the distal part of the leg, due to the new ecological island conditions. However, they are robust with rough areas for strong muscular and ligament insertions, providing stability to the carpal joints, and low speed movement to the animal. The great flexor capabilities, and the limitation in ulnar deviation of the carpus, indicate that P. minor had increased agility in the sagittal plane and restricted transverse movements, while the suggestion of a more unguligrade stance for the species is ambiguous. Thus, the endemic Cypriot hippos developed specialized locomotion, suitable for walking on the rugged terrain of Cyprus, which seems to be different from that of its extant counterparts.

Mobility of solid and porous hollow SiO2 nanoparticles in saturated porous media: Impacts of surface and particle structure

Silica nanoparticles (SiO2 NPs) are of increasing interest in nano-enabled agriculture, particularly as nanocarriers for the targeted delivery of agrochemicals. Their direct application in agricultural soils may lead to the release of SiO2 NPs in the environment. Although some studies have investigated transport of solid SiO2 NPs in porous media, there is a knowledge gap on how different SiO2 NP structures incorporating significant porosities can affect the mobility of such particles under different conditions. Herein, we investigated the effect of pH and ionic strength (IS) on the transport of two distinct structures of SiO2 NPs, namely solid SiO2 NPs (SSNs) and porous hollow SiO2 NPs (PHSNs), of comparable sizes (~200 nm). Decreasing pH and increasing ionic strength reduced the mobility of PHSNs in sand-packed columns more significantly than for SSNs. The deposition of PHSNs was approximately 3 times greater than that of SSNs at pH 4.5 and IS 100 mM. The results are non-intuitive given that PHSNs have a lower density and the same chemical composition of SSNs but can be explained by the greater surface roughness and ten-fold greater specific surface area of PHSNs, and their impacts on van der Waals and electrostatic interaction energies.

Performance Simulation of Tubular Segmented-in-Series SOFC Using Simplified Equivalent Circuit

In previous researches on SOFCs, various kinds of cell shapes have been proposed and many experimental and numerical studies have been carried out. Among them, tubular segmented-in-series SOFCs have an advantage that they can obtain high output voltage since a lot of single cells are connected in series along the cell tube. However, the majority of the numerical studies on SOFCs have been selected planer type as analysis target. In contrast, numerical works on tubular segmented-in-series SOFCs are relatively few. In the case of tubular segmented-in-series SOFC, the current flows along series-connected single cells. Hence, the current path in tubular segmented-in-series SOFC is relatively complicated in comparison with that in planar-type SOFCs. For this reason, a lot of resistance elements are required to make a highly accurate equivalent circuit applicable to simulations of tubular segmented-in-series SOFCs and, therefore, calculation load is very heavy in case no simplification is applied to the equivalent circuit. Hence, in order to simulate performance of tubular segmented-in-series SOFCs, the calculation load per single cell should be alleviated. Considering the above, a method to simplify the equivalent circuit used for the simulation of tubular segmented-in-series SOFCs is proposed in this study. As for the simplified equivalent circuit, a single cell is composed of an electromotive force, anodic and cathodic overvoltages and nine resistance elements. In order to reduce the resistance elements down to nine, the term of correction coefficient is introduced into the simple theoretical expression formula for resistance of each element. The reason of the above correction is to avoid overestimation of power loss due to limitation of current path caused by the rough area division of resistance elements used in the simplified equivalent circuit. With respect to the determination of the correction coefficients, before starting whole simulation of the SOFC tube, circuit simulations of a single cell are carried out for both of the simplified equivalent circuit with nine resistance elements and the detailed equivalent circuit with fine area division and current distributions are calculated for conceivable operating conditions. Based on the numerical results, the power loss of each resistance element is evaluated for both the simplified and detailed equivalent circuit cases. Finally, the correction coefficient of each resistance element contained in the simplified equivalent circuit is determined so as to equalize its power loss obtained through the simplified simulation with the total power loss of the resistances contained in the corresponding area obtained through the detailed simulation. Since the current distribution in the single cell changes depending on both operating temperature and output current, the correction coefficients of nine resistances are determined for various operating conditions. In order to incorporate the correction coefficients in the simulation program for whole tubular segmented-in-series SOFC, their interpolation equations in terms of the temperature and output current are created. By using the correction coefficients for nine resistance elements, the power loss attributed to the detailed current path inside the cell can be taken into account by the simplified equivalent circuit that uses only nine resistance elements. Based on the above proposed simulation method, the authors developed a simulation code for tubular segmented-in-series SOFCs. At first, to confirm the effect of the consideration of detailed current path on the results of the numerical simulation, the temperature distribution obtained through the simulation considering the correction coefficients is compared with that neglecting the correction coefficients. From this comparison, no significant impact of the consideration of the correction coefficients was observed concerning the temperature distribution. Next, the output voltage obtained by the simulation considering the correction coefficients was compared with that neglecting the correction coefficient. As a result, it was found that the output voltage considering the correction coefficients is higher than that neglecting the correction coefficient. The voltage difference was about 20 mV per single cell. In other words, the difference of the output voltage related to the complicate current path inside the cell becomes larger as single cells connected in series increase. This means the need to use some kind of equivalent circuit that can take detailed current distribution into consideration. Although the preprocessing is required to determine the correction coefficients of nine resistance elements, the equivalent circuit proposed in this study is simple but can practically calculate the influence of the detailed current path inside tubular segmented-in-series SOFC, indicating the effectiveness and usefulness of the proposed method.

Drying of a Colloidal Suspension Deposited on a Substrate: Experimental and Numerical Studies

We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass substrate contained either straight rough areas on the borders of an open channel or only straight rough areas. The drying of the suspension was observed with an optical microscope, the light bulb of which acted as an energy source to evaporate the suspension. Moreover, the light bulb of the microscope provided optical pressure due to light. We observed that the colloidal particles were trapped on the rough areas of the substrate and not in the open channel at the end of the drying process. In order to understand the experimental results, we modeled numerically the drying of the suspension using a Molecular Dynamics program. The forces imposed on the substrate by the particles are their weight, the optical pressure due to the light bulb of the optical microscope, the attractive Van der Waals force and the repulsive diffuse layer force. The forces acting between two particles are the attractive Van der Waals forces, the repulsive diffuse layer force and the capillary force. The Gaussian random force (linked to Brownian motion) and the particle liquid viscous drag force (also linked to Brownian motion) are horizontal and applied on one particle. The relation between the normal forces N (forces acting by the particles on the substrate) and the horizontal forces F is Amontons’ third law of friction F≤μkN; in rough areas of the substrate, μk is larger than in smooth areas. This explains that particles are trapped in the areas with high roughness.

Nanosecond laser ablation for improving the strength of CFRTP and aluminum alloy adhesively bonded joints

The improvement of adhesively bonded joints of aluminum alloy and carbon fiber reinforced thermoplastic composites (CFRTP) was achieved by nanosecond laser ablation. Surface morphology, roughness and wettability of CFRTP ablated were studied. Chemical compositions were determined by FTIR and XPS. Tensile-shear tests were performed, and fractured surfaces were analyzed to determine the failure mode. The digital image correlation (DIC) technique was used to observe the micro-scale full-field strain. The durability of joints in extreme conditions was also evaluated. As the laser power increased, the resin was removed, and underlying fibers were exposed, increasing the surface roughness and contact area. This improved the strength of bonded joints. The highest strength of joints was 14.3 MPa when the laser power was 24.5 W, which was approximately 2.2 times of joints without ablation. However, excessive heat input would destroy the CFRTP decreasing the strength. The wettability of CFRTP after ablation was worse due to rough surfaces and fewer polar chemical bonds. Four failure modes were confirmed, and cohesive failure was obtained when the strength of joints was the highest. DIC results revealed the rougher surface after laser ablation could decrease the strain. High residual strength after hygrothermal aging was maintained due to good interface bonding.

Biopolymer-PAA and surfactant-CTAB assistant solvothermal synthesis of Mn-based MOFs: design, characterization for enhanced biological activities

Mn(BTC) (1) MOF is successfully incorporated sodium salt PAA and CTAB composites by solvothermal synthesis to form Mn(BTC)@PAA (2), and Mn(BTC)@PAA@CTAB (3). FT-IR show all typical peaks of 1 in 2, and 3, confirm the presence of 1 in 2 and 3 composites. A similar PXRD pattern of 1–3 suggests the morphology of 1 is unchanged by integrating with biopolymer. SEM EDX analysis show rough surface area, with cylindrical rod and closely bonded morphology and presence of Mn in all composites. TG-DTA analysis show almost equal weight lost at 350–475 °C due to BDC decomposition. UV-Vis diffused reflectance spectra (DRS) exhibited an intense absorption peak around 250 nm assigned to charge transfer transition between ligand and Mn2+ ion. All MOFs tested for antimicrobial activity, 2 effectively inhibits microorganisms’ growth even after three months, due to the slow release of metal ions. Antioxidant studies and DNA cleavage activity carried show positive results.