Concave Surface Research Articles

Tape‐Free, Digital Wearable Band for Exercise Sweat Rate Monitoring

AbstractMonitoring sweat secretion rate is essential for uncovering underlying physical conditions like hyperhidrosis, mental stress, and neural disorders. Often, flexible microfluidic sweat rate monitoring devices use tape as a means of attachment to the skin to tightly seal the collection area. While these single‐use, adhesive‐backed devices have lightweight and thin interfaces for mounting on the skin, their form factor complicates their potential integration with available commercial wearables, such as smartwatches. Here, a tape‐free device, consisting of a 3D‐printed sweat collector with a concave surface that is strapped onto the skin to form an effective seal, is presented. The materials, structure, and dimensions of the sweat collector are optimized for conformal device‐to‐skin contact and efficient capture of sweat. The collector is interfaced with a fluidic microchannel with embedded electrodes for continuous digital monitoring of sweat rate. Long‐term exercise‐induced local sweat rate from multiple body locations in both multi‐subject and longitudinal studies is measured, depicting the correlation between the measured sweat profile and total body fluid loss. The simple installation procedure and reusability of this tape‐free device make it a good candidate for integration with the band of a watch.

How effective is the fire safety education policy in China? A quantitative evaluation based on the PMC-index model

The Fire Safety Education Policy (FSEP) is critical in raising public awareness of fire prevention and reducing man-made fires. The FSEP evaluation system was constructed based on text mining technology and the policy modeling consistency (PMC) index model, and ten representative FSEP were evaluated quantitatively. The results showed that among the 10 FSEP, one policy had the perfect consistency, two had a great consistency, and seven had acceptable consistency. Meanwhile, FSEP with a longer time frame scored higher, while short-term and more specific policies scored relatively lower. The PMC-Surface of representative policies showed that the lower scores of policy release agency (X2) and policy tool (X6) are the main reasons for the concave surface. The findings suggest that FSEP still has much room for improvement regarding policy release agency authority and policy tool selection. This study clarifies the strengths and weaknesses of FSEP in China and provides theoretical references for its optimization.

Au nanorod core in an AgPt cage: Synthesis of Au@AgPt core/cage nanoframes with rough surface and controllable geometry by galvanic replacement

Metallic nanoparticles with intricate nanoframe structures have provoked extensive attention for improving optical and catalytic properties owing to their open structures. However, how to precisely control the geometry shape and surface details of the nanoframes remains a daunting challenge. Herein, we report a novel structure of Au@AgPt core/cage nanoframes with rough surfaces and controllable geometry and surface details based on the galvanic replacement reaction between Ag shells wrapped around gold nanorods and Pt4+ ion. With the increase of Pt4+ ion, the six faces of Ag shell firstly undergo a continuous concaving process to form the concave surface, following by an asymmetric and continuous hollowing-out process started from one side of Ag shell, and in this whole process accompanied by re-deposition process of both silver and platinum on the edges and vertices. We also verify that the prepared Au@AgPt nanoframes have the characteristics of adjustable size, aspect ratio, roughness, skeleton diameter and composition ratio by changing these reaction conditions such as temperature, thickness of Ag layer, and aspect ratio of gold nanorod. This controlled shape evolution also results in abundant localized surface plasmon resonance (LSPR) modes. Multiple absorption bands could be tuned simultaneously from blue (400 nm) to near infrared (1300 nm) range.

Three-dimensional morphological variations in the calcaneus and talus in relation to the hallux valgus angle

BackgroundThe present study aimed to clarify the morphological patterns of the calcaneus and talus that are associated with hallux valgus angle (HVA) by quantifying the differences in the hindfoot bone morphology between left and right sides in HV patients with clear bilateral difference of HVA. MethodsThree-dimensional (3D) computed tomography scans of 32 feet of 16 patients with HV who had right-to-left HVA differences of more than 5 degrees (68.8 ± 8.6 years) were enrolled, and 3D surface models of the calcaneus and talus were generated. A total of 556 and 430 landmarks were placed on the calcaneal and talar surfaces, respectively, to calculate the principal components (PCs) of shape variations. The PC scores were compared between the small and large HVA sides within an individual. ResultsThe calcaneus in patients with a larger HVA (mean, 43.2 degrees) possessed slender calcaneal tuberosity, more medially oriented posterior articular surface in the coronal plane, and narrower and more concave anterior-middle articular surfaces compared to those with a small HVA (mean, 33.7 degrees). The talus with a larger HVA exhibited more medially oriented talar head in the transverse plane and more anteriorly protruded lateral region of the talar head compared to the small HVA. ConclusionsThe morphological patterns of the calcaneus in patients with a larger HVA allows the hindfoot bones to easily rotate in the everting direction, while those of the talus could induce a larger internal rotation of the first metatarsal. These morphological patterns of the calcaneus and talus could be structural factors affecting the HV.

Amphiphilic Bowl-Shaped Janus Particles Prepared via Thiol-Ene Click Reaction for Effective Oil-Water Separation.

Janus particles for oil-water separation have attracted widespread attention in recent years. Herein, we prepared a bowl-shaped Janus particle that could rapidly separate oil and water through a thiol-ene click reaction and selective etching. Firstly, snowman-like composite microspheres based on silica and mercaptopropyl polysilsesquioxane (SiO2@MPSQ) were prepared by a hydrolytic condensation reaction and phase separation, and the effects of the rotational speed and molar ratios on their microscopic morphologies were investigated. Subsequently, bowl-shaped Janus particles with convex hydrophilic and concave oleophilic surfaces were prepared via a thiol-ene click reaction followed by HF etching. Our amphiphilic bowl-shaped Janus particles could remarkably separate micro-sized oil droplets from an n-heptane-water emulsion with a separation efficiency of >98% within 300 s. Based on the experimental and theoretical results, we proposed the underlying mechanism for the coalescence of oil droplets upon the addition of the amphiphilic bowl-shaped Janus particles.

Laser-induced graphene based triboelectric nanogenerator for accurate wireless control and tactile pattern recognition

Accurate control interfaces and high-sensitive tactile sensing are essential for normal and efficient operation of intelligent robots. Despite most research focus on human-machine interface (HMI), little attention is paid to autonomous control interface of the robots. Simultaneous achievement of both accurate control interface and tactile array sensing in one device has been a fundamental challenge in developing intelligent robots. Herein, one device integrated by two different working-mode laser-induced graphene (LIG)-based triboelectric nanogenerators (TENGs) is developed to achieve simultaneously its accurate wireless control and tactile pattern recognition capability. Based on the same triboelectric effect, both the rolling of nylon pellet on the poly(vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) concave surface and the touching on the tactile pattern recognition array can excite the LIG electrodes to generate voltage outputs, which can be further employed for accurate wireless control and real-time tactile sensing (pressure sensitivity of 2.2 V/kPa within 0–2.8 kPa), respectively. When combining with a microprocessor, the accurate control interface layer based on eight parallel freestanding interdigital electrode-based TENGs on a concave cavity of silicone rubber can wirelessly operate motion direction of a miniature car as a proof-of-concept. Meanwhile, the tactile imaging of an 8 × 8 sensing array based on single-electrode TENG can successfully achieve tactile pattern recognition. Consequently, the multifunctional device integrated by two different LIG-based TENGs has achieved simultaneously accurate wireless control and sensitive tactile pattern recognition, which would demonstrate a promising application in metaverse, unmanned vehicles, and intelligent robots.

Simulation-driven Wind Load Analysis and Prediction for Large Steerable Radio Telescopes

Large steerable radio telescopes can rotate in azimuth and elevation, with various upwind postures and complex wind load characteristics. In order to 5 Corresponding authors obtain the wind load distribution on the reflector and the wind force coefficients in different upwind postures, this work took the reflector of the QiTai Telescope in Xinjiang as the object. The wind pressure distribution, drag coefficient, side force coefficient, lift coefficient, and total force coefficient of 361 groups of reflectors with different upwind postures were calculated and analyzed by a numerical simulation method. The results show that the force on the reflector when the concave surface faces the wind is significantly greater than when the convex surface faces the wind. The surrogate models for calculating wind force coefficients were established based on the polynomial response surface model (PRSM) and regularized minimum-energy tensor-product spline (RMTS). The adjusted R-squared of RMTS is 0.98, and the root mean square error is below 0.1, which proves RMTS is significantly better than PRSM. Compared with the numerical simulation values, the absolute errors of the drag coefficient, side force coefficient, lift coefficient, and total force coefficient of the reflector with azimuth and elevation of 45° predicted by RMTS are 0.02, 0.027, 0.032, and 0.046, respectively. The relative errors are 2.42%, 2.76%, 2.23%, and 2.43% , respectively. It is proved that the RMTS surrogate model is reliable and that the predicted data can fast provide sufficient information for the wind-resistant design of the large steerable radio telescopes.

Trueness and precision of milled and 3D printed root-analogue implants: A comparative in vitro study

ObjectivesThe present study aimed to evaluate the accuracy (trueness and precision) of titanium and zirconia multi-rooted root analogue implants (RAIs) manufactured by milling and 3D-printing. MethodsA multi-rooted RAI was designed based on a mandibular second molar segmented from cone-beam computed tomography (CBCT). The manufactured RAIs were divided into four groups: 3D-printed titanium (PT) and 3D-printed zirconia (PZ) (n=10 each), as well as milled titanium (MT) and milled zirconia (MZ) (n=5 each). The specimens were scanned with a high-precision scanner, and the scanned data were imported into 3D-measurement software to evaluate the precision and trueness of each group. Root mean square (RMS) deviations were measured and statistically analysed (One-way ANOVA, Tukey's, p≤0.05). ResultsPZ showed the highest precision with RMS value of 21±6 µm. Nevertheless, there was no statistically significant difference in precision among the other groups. Regarding trueness, MZ showed the highest trueness with RMS value of 66±3 µm, whereas MT showed the lowest trueness result. Inspection sections showed that MT had significantly high RMS deviation in the furcation area (612±64 µm), whereas PZ showed significantly high RMS deviation at the apical area (197±17 µm). ConclusionsThe manufacturing process significantly influenced the RAI accuracy. PZ exhibited the highest precision, whereas MZ exhibited the highest trueness, followed by PT. Finally, our results suggest that 3D-printing can reproduce concave surfaces and less accessible areas better than milling. Clinical SignificanceMilled and 3D-printed RAIs showed promising results in terms of precision and trueness. However, further clinical research is needed to advocate their use as immediate implants. Additionally, the inherent volumetric changes of the various materials during manufacturing should be considered.

Calcium sulphoaluminate cement from solid waste with nano-TiO2 addition for high-efficiency CO2 capture

Calcium sulphoaluminate cement from solid waste (WCSA) has a relatively lower sintering temperature and low CO2 emission, meanwhile, the low cost of WCSA and the good CO2 absorption capacity make it one of the current hot topics of research. In this work, based on the optimal water-cement ratio, the effect of titanium oxide (TiO2) on the pore structure and the hydration process of WCSA were explored. The hydration process and microscopic evolution were studied by compressive strength test, carbonization test, Brunauer-Emmet-Teller measurement (BET), X-ray diffraction (XRD), the heat of hydration, thermogravimetric analysis (TG), and scanning electron microscope (SEM). The effect of nano-TiO2 on the carbon sequestration behavior of WCSA was also analyzed. The results show that WCSA with a water-cement ratio of 0.4 is the optimal carbonization substrate and nano-TiO2 will make the pore structure more uniform and dense, simultaneously increasing the adsorption pressure for the CO2. Meanwhile, the nano-TiO2 can effectively promote and regulate the crystallization, nucleation, and growth of ettringite crystals. It can be found that the WCSA containing 1% nano-TiO2 has the highest carbon capture ability among all the contents, and the ettringite crystal is concave hexahedron. The research considered that the concave surface with large specific surface energy can effectively increase the contact area between CO2 and ettringite, which greatly improved the CO2 absorption of ettringite. Overall, WCSA containing nano-TiO2 may provide some new opportunities for efficient carbon capture.

Specular Surface Shape Measurement with Orthogonal Dual-Frequency Fourier Transform Deflectometry

Three-dimensional (3D) shape measurement for specular surfaces is becoming increasingly important in various applications. A novel orthogonal dual-frequency fringe is proposed in the specular surface shape measurement to overcome the phase jumping and discontinuities in spatial phase unwrapping. The fringe recalibrated high-accuracy phase information from its high-frequency fringe component with low-ambiguity phase information from its low-frequency fringe component. An improved Fourier transform deflectometry method based on the orthogonal dual-frequency fringe is proposed to measure 3D specular surface shapes. Simulation results showed that the orthogonal dual-frequency Fourier transform deflectometry (ODD) method could precisely reconstruct flat surfaces with an error of 2.16 nm rms, and concave surfaces with an error of 1.86 μm rms. Experimental results showed that the reconstructed shapes of both the flat mirror and the concave mirror measured by the ODD measurement system were highly comparable to those obtained by the phase-measuring deflectometry (PMD) method. This new fringe provides a distinctive approach to structured pattern construction and reduces the phase unwrapping ambiguities in specular surface shape measurement. The ODD method can achieve accurate 3D shape measurement for specular surfaces by sampling only one fringe, providing a possible basis for future real-time measurement of specular surfaces.

Trapping of single atom and precise control of its coupling strength in micro-optical cavity

Cavity quantum electrodynamic system with strongly coupled single atoms provides a good platform for studying quantum information processing, quantum simulation, quantum network, and distributed quantum computing. Cooling and trapping single atoms is a crucial technique in the quantum technology. At present, in a high-finesse cavity with finite space, cooling and trapping single atoms is a big challenge, even though it is a mature technique for free space. Great efforts have been made to cool and trap single atoms inside a cavity, and for a trapped atom its lifetime has reached as long as tens of seconds. Developing a more flexible method of cooling and trapping single atoms in a cavity is still essential for a strongly coupled cavity quantum electrodynamic system. In this work, we demonstrate experimentally that a single cesium atom in a cavity can be trapped by utilizing a single optical tweezer settled in cavity mode, and its lifetime is (2.60 ± 0.18) s. The experiment is carried out in a Fabry-Perot cavity, which is assembled by two concave mirrors each with a curvature radius of 100 mm, and cavity length of 335 μm. The concave surfaces are highly reflective, and the cavity has a finesse of 6.1 × 10<sup>4</sup>. The 1080 nm optical tweezer with a waist of 2 μm is formed by an achromatic lens group with a numerical aperture of 0.4. At first, the precooled atomic assemble released from the magneto-optical trap (MOT) is transferred into cavity mode by an optical dipole trap with a waist of 36 μm. Then, one of the successfully transferred atoms is captured by the optical tweezer with the aid of cavity cooling mechanism. A blue detuned cavity locking laser is used as a standing-wave optical trap along the cavity axis. The signal of successfully trapped one atom is obtained by recording transmission of the cavity that will decrease owing to the strong coupling induced vacuum Rabi splitting. Finally, we demonstrate the precise manipulation of the atom-cavity coupling strength, which is achieved by scanning the position of the trapped atom step by step by using a high-precision translation stage. The system realized in this work can be used to study the dynamics of single atom-photon interactions with adjustable coupling strength. In addition, the mechanism adopted in this work is compatible with constructing tweezer arrays inside cavity mode, and thus possesses more flexibility and great potentials in cavity-based quantum entanglement and quantum simulation.

SPATIAL VARIABILITY STATUS OF SELECTED SOIL PROPERTIES IN NORTH-EAST AKWA IBOM STATE, NIGERIA

Spatial variability status of selected soil properties in North-east Akwa Ibom State, Nigeria was assessed. The aim was to establish baseline information on the spatial variability status of selected soil properties in North-east Akwa Ibom State for site -specific and sustainable soil management. A terrain attribute (plan curvature) that is capable of capturing the short-scale spatial variability of soil properties in the field was used to guide field sampling. Plan curvature map was generated from digital elevation model (DEM) of the study area acquired from United State Geological Survey (USGS) at 30m resolution. The plan curvature map was classified into straight, convex and concave surfaces. Modified conditioned Latin hypercube sampling method was used in selecting observation points. Each observation point was purposefully selected to fall within the three classes of the plan curvature map to give a good coverage of both feature space (terrain attributes) and geographical space (study area). Soil samples were collected from each observation point at depths of 0-30 cm and 30-60 cm using soil auger. A total number of 152 soil samples were collected in the study area for laboratory analysis. Data generated were subjected to analysis of variance (ANOVA) and means were separated using least significant difference (LSD) at 5% level of significance. The depth interval of 0-30cm and 30-60 cm were integrated to form depth interval of 0-60 cm and data with skewed distribution were log transformed for semivariogram analysis. Soil properties were then subjected to semi-variogram analysis. The results showed that plan curvature was able to capture short scale spatial variation in some soil properties under study. Soil texture was sand in the surface and subsurface soils of both convex and concave slope while in straight slope, the soil texture was sand in the surface and loamy sand in the subsurface. Soil pH was strongly acidic in both straight and concave slope and slightly acidic in convex slope in both surface and subsurface soil. Organic carbon was high in concave and convex slope and very high in straight topography in both surface and subsurface soils. Total N was low in the convex and concave slope but moderately low in straight terrain. The available P of straight slope was higher than that of concave and convex slope.From the semi-variogram analysis, all the selected soil properties exhibited spatial dependence within some distances. The strength of the spatial dependence varied from moderate for sand, silt, soil pH, organic carbon, total N and available P to weak for clay and strong for exchangeable K. The best fitted models were Exponential for sand and silt; Gaussian for available P and Spherical for clay, pH, organic carbon, total N and exchangeable K.The range of autocorrelation was 136.2 m for sand, 76.4m for silt, 1.6 m for clay, 1.69 m for soil pH, 9.4 m for organic C, 7.1m for total N, 39.2 m for available P and 7.8 m for exchangeable K. This shows that beyond these ranges, the selected soil properties should be managed differently

An Inventory Model with Deteriorating Items under Advertisement Efforts

In this paper, we proposed an inventory model with deteriorating items under advertisements efforts. The deterioration of the items reduces the quality of the items and advertisement is a one type of business policy which increases the sale of items. Nowadays a lot of companies are using advertisements effort for more sales of items in the short time and the demand is presumed to be reliant on the selling price, and stock is additionally believed to be reliant on environmental initiatives and the impact of advertising. Here we considered purchase price is dependent on order size and all unit quantity discount is also considered. Here, the holding costs increase and are considered time-dependent. This article, aims to find a gross profit function that depends on selling price, greening efforts, and cycle time. Here we develop an algorithm to find a feasible solution. The profit function's concave surface is represented graphically. A numerical example is presented for the justification of the model and also shown the observations through sensitivity analysis.

Flow mechanism and heat transfer characteristic of sweeping jet impinging on confined concave surfaces

The sweeping jet actuator (SJA), a type of fluid oscillator, has attracted considerable attention in the areas of enhanced heat transfer and flow control. In this study, an unsteady Reynolds-averaged Navier–Stokes numerical investigation (k–ω baseline) was conducted to evaluate the flow mechanisms and heat transfer characteristics of a sweeping jet (SJ) on a confined concave surface. A conventional oscillating jet with a unit aspect ratio was used to generate the SJ. The heat transfer at the target surface and the flow details inside the flow field are discussed in detail to analyze the mechanism of the effect of SJ on impinging cooling. First, an appropriate numerical model was selected based on a comparison with a previous experiment. Subsequently, the time-averaged and time-resolved flow field and heat transfer results were investigated at three target distances for three different Reynolds numbers. The unsteady time-averaged results show that the SJ exhibits better heat transfer performance at higher Reynolds numbers and narrower target spacings than circle jet, which improves by 13% at Re = 30 000, H/D = 1. Subsequently, the turbulent kinetic energy and velocity loss theories were combined to compare the time-averaged and time-resolved flow field details of the two jets. The heat transfer characteristics of the target surface and the flow details inside the flow field in time and space were effectively correlated. Finally, the topology and three-dimensional (3D) vortex structure inside the confined channel were remodeled to better understand the unsteady sweeping process and provide theoretical support for subsequent applications.

An Interesting Case Report of Acquired Triradiate Periungual Fibrokeratoma and its Dermoscopic Features.

Dear Editor, A 6-year-old girl attended our nail OPD (Out Patient Department) for an opinion on rapidly growing two finger-like projections at the proximal nail fold of her right fourth finger for 3 months. The growth was painless and asymptomatic. There was no history of trauma or any significant systemic disease. On clinical examination, there were two finger-like projections with keratotic tips that were fused proximally at the proximal nail fold of her right fourth finger. The underlying nail plate was normal except for the depression with a concave surface underneath the tumor. There was no evidence of a shagreen patch or angiofibroma on the face. There was no history of convulsions in the past or similar family history. On dermoscopy with DermLite DL4, contact polarized view at 10× magnification, we could appreciate two filiform rod-like projections with one more projection starting to grow from the side. There were five zones in each projection. From proximal to distal the zones were a white structureless zone, a red structureless area, a structureless brown area, a well-delineated dark brown area, and a lighter overhanging rim-like brown area at the distal-most end [Figure 1].Figure 1: Filiform projections (Dermoscopic view - Dermlite DL4,10X)We made a provisional diagnosis of acquired periungual fibrokeratoma. Our differentials were supernumerary digit, acral fibromyxoma, and wart.[1] The lesion was completely excised under a digital block. The proximal nail fold was everted by giving two incisions on either side of the growth and the tumor was exposed using stay sutures on either side. We dissected the tumor from the underlying nail plate and the overlying proximal nail fold. The tumor was excised in toto and sent for histopathology. The incisions were closed with 5–0 prolene and suture removal was done on day 10. The postoperative period was uneventful with no evidence of recurrence after 6months and the patient was kept on follow-up. On histopathology, the finger-like projections [Figure 2] were seen which were lined by horny hyperkeratosis, hypergranulosis, acanthotic epidermis with the dermis showing dense collagen fibers, dilated thin-walled capillaries, and fibroblasts [Figure 3].[2]Figure 2: Finger-like projections lined by hyperkeratosis, hypergranulosis, and acanthotic epidermis (H & E, 4×)Figure 3: The dermis with dense collagen fibers, dilated thin capillaries, and fibroblasts (H & E, 40×)The dermoscopic and histopathological correlation of this case is as follows [Table 1].Table 1: Dermoscopic and Histopathologic correlationBased on the clinical, dermoscopic, and histopathological correlation, the diagnosis of Type 2 acquired periungual fibrokeratoma (AUFK) was made. AUFK are benign fibrokeratotic tumors.[3]The classical presentation of AUFK is an asymptomatic single-skin colored nodule with a hyperkeratotic tip emerging from the proximal nail fold or directly from the nail bed. The pathogenesis is not yet validated; however, the role of trauma, presence of factor XIIIa positive dermal dendrocytes, preceding streptococcal infection, and human papillomavirus infection[4]have been postulated as the etiological factors. The rare variant of AUFK called multibranched acquired periungual fibrokeratoma was first described in 2014 by Moriue et al.[5] In this letter, we describe one such entity which was successfully diagnosed and treated. AUFK typically affects middle-aged adults with slight male predominance. It is more often localized to toe nails rather than fingernails, most commonly in the periungual area. Our case is unique due to its occurrence in fingernails, and its presentation during the first decade of life in a female. In this, we tried to correlate the histopathological and dermoscopic findings which might help in the preoperative diagnosis of this condition. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Application of landmark guided screw in ankle syndesmos diastasis surgery

Objective: Screw used in the treatment of ankle syndesmosis diastasis can be placed in malposition. Our aim in the study is to define a new technique for sending the screws in the right direction. Material and Methods: The ankle tomography of 188 patients was evaluated. First, the medial malleolus root was divided into three equal parts in axial CT section. Then, a screw model was drawn to fit the fibula to the concave surface in the tibia in another axial CT section where the syndesmosis joint is prominent.These two axial CT sections were placed on top of each other with computer program. Results are noted Results: While 95.7% of the screw simulations were passing through the front 1/3, 4.3% through the middle 1/3, the screw did not pass through the rear 1/3 in any simulation. 187 of these lines passed between the most lateral peak of the fibula and 3 mm posterior. Conclusion: During diastasis surgery, the insertion site of the drill should be chosen between the sharp peak of the fibula and the 3mm posterior. When the drill is placed in this way and directed 1/3 anterior to the medial malleolus, our screw will be sent in the correct position. Our study revealed that the surgical treatment of syndesmos dissociation with screws is a landmark independent of the patient's position and the skill of the surgeon. There is no other study like this study. However, considering the consistency of our results with the literature, we believe that our study can guide surgeons in practical applications

Solar evaporation performance of 3D-printed concave structures filled with activated carbon under low convective flow

Three-dimensional (3D) geometries were 3D-printed to make unique geometries filled with activated carbon to improve water transport and photothermal conversion when used as solar evaporators. Evaporation was modelled to study the different aspects affecting the evaporation performance of five geometries. Low convection airflow, concave surface evaporation, light reflection and natural convection were investigated in a 2D flat surface and four 3D structures presenting a concave surface. It was revealed that the effect of surface-to-surface radiation has a limited impact on the evaporation rate (1%), which depends linearly on the evaporation area. We have undoubtedly shown that, both in forced and natural convection, concavity in the structure should be avoided as it leads to moisture-saturated air. On the contrary, the 3D structure should be as open as possible to allow the unsaturated air to escape.

Bessel acoustic-beam acoustic lens for extending the depth of field of detection in optical-resolution photoacoustic microscopy.

As an important part of optical-resolution photoacoustic microscopy, the acoustic lens is responsible for efficient collection of photoacoustic signals. The spherical focused acoustic lens is commonly used in photoacoustic microscopy because of its efficient detection of the photoacoustic signal in the focus area. However, the narrow depth of field of the spherical focused acoustic lens limits the expansion of the depth of field of the photoacoustic microscopy. To solve this problem, a Bessel acoustic-beam acoustic lens is proposed. The Bessel acoustic-beam acoustic lens replaces the spherical concave surface with a conical concave surface to generate a Bessel acoustic beam with non-diffraction. Using the simulation model of Bessel acoustic-beam acoustic lens constructed by COMSOL Multiphysics, it is verified theoretically that the Bessel acoustic-beam acoustic lens can improve the depth of field of detection by ∼2 times. The Bessel acoustic-beam acoustic lens can further promote the capability of high-speed and large volumetric imaging of optical-resolution photoacoustic microscopy and will be helpful in the acquisition of physiological and pathological processes.

Static Compressive Properties of Polypropylene Fiber Foam Concrete with Concave Hexagonal Unit Cell

For the purpose of studying the influence of fiber on the negative Poisson’s ratio effect of foam concrete, a concave hexagonal unit cell structure of polypropylene fiber foam concrete was proposed. The effects of different fiber volume contents on the structural mechanical parameters, Poisson’s ratio, and energy absorption capacity of the unit cells were studied by static compression of concave hexagonal unit cells and cube specimens. The results show that the compressive strength of foam concrete is reduced by adding polypropylene fiber, and the peak stress of concave hexagonal unit cells decreases less rapidly than that of cube specimens. The proper amount of polypropylene fiber can enhance the deformation ability of the unit cells in foam concrete, and the Poisson’s ratio of the unit cells in foam concrete with 1.5% fiber content is the lowest. In the process of failure of concave hexagonal unit cells, the failure phenomenon is mainly concentrated on the concave surfaces on both sides, and the cracks are distributed in the form of “upper left and lower right” or “lower left and upper right”. When the content of polypropylene fiber is 0.5%, the total energy absorbed by the concave hexagonal cells in the compression deformation process increases by 12.98%.

Effect of Fly Ash Fraction and Mixing Process Variables On Mechanical Properties of Polymer Composites

The development of material technology continues to be carried out to meet the needs of engineering materials which are increasing day by day and are environmentally friendly or green. In this study, the process of making epoxy resin composites with fly ash was carried out from the combustion process of a power plant. This study aims to determine the strength of the mechanical properties between the epoxy resin and fly ash weight fraction by stirring treatment in the mixing process using tensile, flexural, and impact tests, microscopic examination, FTIR, and X-RD analysis. The treatments were mixing epoxy resin and fly ash with a weight fraction of 10%, 20%, and 30%, stirring speeds of 100 rpm, 150 rpm, and 200 rpm, for 10 minutes, 20 minutes, and 30 minutes. The results showed that the F2S3T3 composite had a greater tensile strength of 31,94 MPa, while the other composites had a tensile strength above 22-30 MPa, and the lowest was 13,07 MPa in the F1S2T3 composite. The maximum modulus of elasticity is found in the F3S3T1 composite with a value of 11,12 MPa, and the lowest is found in the F1S2T3 composite at 2,06 MPa. The F3S2T2 composite has a maximum flexural strength of 33,32 MPa, and the lowest composite F2S2T1 is 17,40 MPa with a flexural modulus of 270,41 MPa. The maximum flexural modulus in the F1S1T1 composite with a value of 382,76 MPa with a flexural strength value of 28,82 MPa. TheF2S1T2 composite has an impact energy of 6,94 Joules with an impact strength of 203,47 MPa, and there are 2 composites that have the same impact energy value of 5,20 Joules, namely F3S2T2, and F3S1T3. From SEM observations, the fracture surface of the composite has a concave and prominent surface, but a lot of dust is trapped so it affects the bond in the matrix and reinforcement.