Degree Of Bending Research Articles

A flexible triboelectric nanogenerator based on wave structure PDMS for joint monitoring in basketball training

Recently, intelligent sports wearable devices have attracted widespread attention. Hence, we designed a wave-structure triboelectric nanogenerator (W-TENG) for joint monitoring in basketball training. The self-powered pressure sensor is mainly composed of polydimethylsiloxane (PDMS) film and aluminum foil with corrugation characteristics. The wave structure of the PDMS film is designed based on sine waves, and results have indicated that the higher the amplitude, the higher the sensing performance of the W-TENG. Moreover, the W-TENG has two sensing monitoring areas. For low pressure areas, the sensing sensitivity of the W-TENG is 3.564 V kPa−1 and 37.644 nA kPa−1. For high pressure areas, the sensing sensitivity of the W-TENG is 0.024 V kPa−1 and 19.92 nA kPa−1. This W-TENG pressure sensor can be installed at the joints of basketball players’ bodies to monitor the degree of joint bending. This design can facilitate the development of wearable basketball training devices.

Helcionelloids from the Cambrian Fortunian of the Northern Yangtze Platform, China

AbstractA study of the morphological and microstructural characteristics of helcionelloids from the Nanjiang area (north Sichuan, China) at the northern Yangtze Platform was undertaken, in order to understand their phylogenetic position. Helcionelloids fossils from the Kuanchuanpu Formation of the Changtanhe–Maolinzi section include 7 genera and 11 species. There are distinct differences in the degree of shell bending, the apical morphology and apex position, the outline of the aperture and the height of the shell, all of which constitute important identification features. Although helcionelloid apices exhibit varying degrees of rotation towards the aperture, they do not show any signs of evident distortion. A pair of basally‐symmetrical muscle scars are discovered on the shells of helcionelloids (such as Bemella simplex), showing a distinct difference when compared with those of the stem‐group gastropod (e.g., Pelagiella). The prismatic shell layer of helcionelloids has been observed, which are common components in Cambrian molluscs, but differ significantly from the dense layer microstructure found in contemporary molluscs. The microstructures, muscle scars and morphological characteristics demonstrate that helcionelloids represent a stem‐group of molluscs.

Support stiffness effects on damage behavior of thin-walled composite interference-fit joints in the installation

Interference installation-induced local interface damage becomes the source of bearing failure in service, which severely restricts the reliable application of composite interference-fit joints. To this end, support stiffness effects on interface damage behavior of thin-walled composite interference-fit joints in the installation was systematically investigated in this paper. The mechanical response and interface damage behavior of the joints were evaluated and compared by interference installation experiments and scanning electron microscopy (SEM). The effects of different support stiffness and lap type on the pressing-in load and interface damage were analyzed. Damage formation mechanism and suppression strategy during installation were discussed. Results show that the weaker the support stiffness is, the greater the bending degree caused by the bottom cantilever is, and the more severe the corresponding interface damage is. Increasing the number of laminated plates only increases the value of the pressing-in load, and has a very limited effect on the interface damage state. To reduce the interface damage of the joints in the installation, in addition to maintain the best interference-fit, keep a considerable value on the bottom support stiffness is also very necessary.

Analisis Pengaruh Geometrik Jalan Terhadap Kecelakaan Lalu Lintas

The geometric design of the road must comply with the requirements. Otherwise, it will affect the increasing traffic accidents. Traffic accidents are an indicator of road safety. This study aimed to determine the location of accident-prone areas (black spots) and the relationship between geometric road conditions and traffic accidents on the Garut – Tasikmalaya road section via Cilawu. The method used in this research is polynomial linear regression analysis with variable X relationship, consisting of stopping sight distance, overtaking sight distance, bend radius, and degree of curvature. The Y variable is the EAN (Equivalent Accident Number) value. The geometric road data used in this study is primary data directly taken in the field, while traffic accident data is secondary data. The analysis results by calculating the EANc value show that bends one and bends two are the locations of accident-prone areas (black spots). Except for overtaking sight distance, the relationship between road geometry for bend radii, stopping visibility, and degree of curvature to traffic accidents are closely correlated, which means it has quite an effect on accidents. Overtaking sight distance has little effect on accidents.

A navigation method for paddy field management based on seedlings coordinate information

Compared to tillage, transplanting, and harvesting operations in paddy fields, field management operations such as spraying and weeding require completing tasks along the rice seedling rows to minimize seedling damage and reduce operational losses. Visual navigation, as a commonly used navigation method, can identify rice seedling rows, but it is susceptible to complicated paddy field environments. To address these challenges, our study combines UAV (unmanned aerial vehicle) surveying technology with the YOLOv5s object detection algorithm and proposes a navigation method for paddy field management based on seedling coordinate information. Firstly, the YOLOv5s object detection algorithm was used to identify and locate rice seedling points in the UAV image, and a coordinate transformation model was established to extract the geographic coordinates of the seedling points. Secondly, in order to classify the recognized seedling points into different seedling rows, a classification algorithm was proposed, and the improved RANSAC algorithm further promoted the classification effect. Once again, to obtain a smooth navigation path for agricultural machinery navigation, B-spline curves were used to approximate the classified seedling points. Finally, the generated navigation paths were written into the navigation controller, and the navigation performance was tested on flat ground and paddy fields using a vehicle platform. The results of the flat ground test indicated that different bending degrees have a significant impact on the lateral error. When the bending degree was large, the maximum lateral error was less than 7 cm, and when the bending degree was small, the maximum lateral error was less than 4 cm. The navigation accuracy of RMS in the flat ground test was 2.7 cm. In the paddy field experiment, due to the influence of loose soil surfaces and potholes, the maximum lateral error was about 16 cm. The navigation accuracy of RMS in the paddy field experiment was 5.9 cm, which can meet the operational requirements. The experimental results show that the proposed navigation method can achieve automatic navigation of agricultural machinery along curved rice seedling rows under complex paddy field environments, such as light change, seedling shortage, uneven road surfaces, and curved seeding rows.

Zinc cobaltite nanobelts on carbon cloth in flexible supercapacitors for clean and efficient energy storage

Bimetallic oxides that include cobalt and zinc have become more and more popular as ideal electrode materials for pseudocapacitive applications because of their high specific capacitance (Cs) and remarkable electrochemical characteristics. In this study, a hydrothermal approach was employed to successfully prepare hierarchical zinc cobaltite (ZnCo2O4) nanobelts coated on activated carbon cloth (ZnCoNB@CC) to enhance the performance of supercapacitors (SCs). The exciting ZnCoNB@CC electrode material has a high Cs of 1758 F g−1 at a current density of 1 A g−1 and an outstanding rate capability of about 78% at 5 A g−1. After 6000 GCD cycles, it exhibits notable cycling stability by holding 95.4% of its specific capacitance. Importantly, the assembled hybrid SCs achieve a high power density of 1032.45 W kg−1 at an energy density of 82.36 Wh kg−1. It also displays remarkable flexibility at various degrees of bend, in addition to a slight change in capacitance after 3000 CV cycles are repeatedly performed at each bent position. Hence, the utilization of the ZnCoNB@CC as an electrode is a highly advantageous choice for the development of hybrid flexible SCs with exceptional performance capabilities. The ZnCoNB@CC is a favorable option for high-performance flexible SCs due to its remarkable pseudocapacitive charge storage properties. The synthesis process, outstanding electrochemical performance, and special adaptability of the ZnCoNB@CC electrode make our research distinctive.

Numerical Simulation of 3D Flow Structure and Turbulence Characteristics near Permeable Spur Dike in Channels with Varying Sinuosities

Owing to the different degrees of bending in rivers in nature, it is difficult to conduct experiments in situ. In this study, the renormalization group (RNG) k-ε turbulence model in ANSYS Fluent was used to analyze the three-dimensional flow structure and turbulence characteristics near a spur dike and to evaluate the variation trend of flow in rivers with different degrees of bending. The results show that in channels with different curvatures, the vortex appears between the spur dikes and is disturbed by the permeable hole, and the backflow area moves downstream. The strength of secondary flow (SSF) fluctuates greatly in the vicinity of the spur dike and the downstream region, and the peak value appears 3.22 m (21.5 times L) away from the inlet of the bend. The SSF increases as the bend curvature increases. The SSF displays similar variation trends in the three kinds of bends. The peak value of normalized turbulent kinetic energy (NTKE) appears 3.14 m away from the entrance of the bend, the NTKE is the largest in the 45° bend and the smallest in the 180° bend, and it decreases only at distances of 3.25–4.19 m away from the entrance of the bend as the bend curvature increases.

Ceramic hybrid nanofiber-based elastic scaffold pressure sensor with good sensitivity, breathability, and washability

Flexible pressure sensors have recently attracted increasing attention. Piezoresistive sensors are widely used in wearable devices, human health monitoring, electronic skin, human-computer interactions, and other fields owing to their good sensitivity and rapid response. The assembly of a pressure sensor using SnO2–ZnO hybrid nanofibers is proposed in this study to improve its performance. The heterojunction at the interface between ZnO and SnO2 facilitates electron transfer from SnO2 to ZnO by suppressing electron-hole recombination and accelerating electron motion in ZnO. The scaffold sensor, as compared to other reported pressure sensors, exhibits better flexibility, optimized sensitivity, and pressure sensing range, and can detect dynamic pressure over a wide range (0–60 kPa). The sensor exhibits strong sensitivity (11.5 kPa−1), fast response and recovery times of 42 and 28 ms, respectively, and durable cyclic stability (600 cycles). This sensor can quickly detect human motion from subtle deformations, including weak changes in the joints of the fingers, wrists, and elbows, with a bending degree of approximately 20°. Owing to its excellent performance, breathability, and washability, it can be directly attached to skin or clothing for long-term use and has broad application prospects in wearable electronics.

Finite element analysis comparing a PEEK posterior fixation device versus pedicle screws for lumbar fusion

BackgroundPedicle screw loosening and breakage are common causes of revision surgery after lumbar fusion. Thus, there remains a continued need for supplemental fixation options that offer immediate stability without the associated failure modes. This finite element analysis compared the biomechanical properties of a novel cortico-pedicular posterior fixation (CPPF) device with those of a conventional pedicle screw system (PSS).MethodsThe CPPF device is a polyetheretherketone strap providing circumferential cortical fixation for lumbar fusion procedures via an arcuate tunnel. Using a validated finite element model, we compared the stability and load transfer characteristics of CPPF to intact conditions under a 415 N follower load and PSS conditions under a 222 N preload. Depending on the instrumented levels, two different interbody devices were used: a lateral lumbar interbody device at L4–5 or an anterior lumbar interbody device at L5-S1. Primary outcomes included range of motion of the functional spinal units and anterior load transfer, defined as the total load through the disk and interbody device after functional motion and follower load application.ResultsAcross all combinations of interbody devices and lumbar levels evaluated, CPPF consistently demonstrated significant reductions in flexion (ranging from 90 to 98%), extension (ranging from 88 to 94%), lateral bending (ranging from 75 to 80%), and torsion (ranging from 77 to 86%) compared to the intact spine. Stability provided by the CPPF device was comparable to PSS in all simulations (range of motion within 0.5 degrees for flexion–extension, 0.6 degrees for lateral bending, and 0.5 degrees for torsion). The total anterior load transfer was higher with CPPF versus PSS, with differences across all tested conditions ranging from 128 to 258 N during flexion, 89–323 N during extension, 135–377 N during lateral bending, 95–258 N during torsion, and 82–250 N during standing.ConclusionUnder the modeled conditions, cortico-pedicular fixation for supplementing anterior or lateral interbody devices between L4 and S1 resulted in comparable stability based on range of motion measures and less anterior column stress shielding based on total anterior load transfer measures compared to PSS. Clinical studies are needed to confirm these finite element analysis findings.

Confluence simulations based on dynamic channel parameters in the grasslands lacking historical measurements

Technology has greatly promoted ecohydrological model development, but runoff generation and confluence simulations have fallen behind in ecohydrological model development due to limited innovations. To fully understand ecohydrological processes and accurately describe the coupling between ecological and hydrological processes, a distributed ecohydrological model was constructed by integrating multisource information into distributed dynamic process model (DDPM). We mainly describe runoff generation and convergence modules. Based on the improved HBV model and degree-3 h factor method, runoff generation and snow routines were constructed for semiarid grassland basins. In view of meandering and variable steppe river channels and steep hydrological relief characteristics, a confluence module was constructed; the 1-km bend radius equivalent concept was innovatively proposed to unify river channel bend degrees. The daily runoff simulation validation results obtained using two datasets were R2 = 0.947 and 0.932, NSE = 0.945 and 0.905, KGE = 0.971 and 0.680. In the 3-hour flood simulations, the DDPM could better restore small long-distance water flows than the confluence method that did not consider actual river lengths or bend energy losses; the DDPM more accurately simulated the flood peak arrival time than the confluence method that did not consider overflow. The simulated mainstream overflow frequency increased by 0.84/10 years, and significant interaction periods of 10 to 13 years occurred with local precipitation, ecological status, and global climate change. An approximately 2-year lag occurred in the global climate change response. This study helps us further understand and reveal the ecohydrological processes of steppe rivers in semiarid regions.

A Concentric Tube Steerable Drilling Robot for Minimally Invasive Spinal Fixation of Osteoporotic Vertebrae.

Spinal fixation with rigid pedicle screws have shown to be an effective treatment for many patients. However, this surgical option has been proved to be insufficient and will eventually fail for patients experiencing osteoporosis. This failure is mainly attributed to the lack of dexterity in the existing rigid drilling instruments and the complex anatomy of vertebrae, forcing surgeons to implant rigid pedicle screws within the osteoporotic regions of anatomy. To address this problem, in this paper, we present the design, fabrication, and evaluation of a unique flexible yet structurally strong concentric tube steerable drilling robot (CT-SDR). The CT-SDR is capable of drilling smooth and accurate curved trajectories through hard tissues without experiencing buckling and failure; thus enabling the use of novel flexible pedicle screws for the next generation of spinal fixation procedures. Particularly, by decoupling the control of bending and insertion degrees of freedom (DoF) of the CT-SDR, we present a robotic system that (i) is intuitive to steer as it does not require an on-the-fly control algorithm for the bending DoF, and (ii) is able to address the contradictory requirements of structural stiffness and dexterity of a flexible robot interacting with the hard tissue. The robust and repeatable performance of the proposed CT-SDR have been experimentally evaluated by conducting various drilling procedures on simulated bone materials and animal bone samples. Experimental results indicate drilling times as low as 35 seconds for curved trajectories with 41 mm length and remarkable steering accuracy with a maximum 2% deviation error.

Rapid prediction model of effective thermal conductivity of plain weave fabric in space environment

The prediction of effective thermal conductivity of aerospace insulation materials is crucial for insulation design and radiation characteristics control of space targets. In this paper, a rapid and accurate prediction model is proposed for the effective thermal conductivity of plain weave fabrics in space environments. This model assumes that the cross-sectional shape and bending degree of yarns within aerospace fabrics remain unchanged. To represent the structural characteristics of the plain weave fabric, a dimensionless parameter called "f" is defined. Numerical simulations are conducted to investigate the effects of fabric structure, temperature, and yarn thermal properties on the effective thermal conductivity of multilayer fabrics. Three parameters are identified as the most influential factors for the effective thermal conductivity of plain weave fabrics: the structural parameter f, and the axial and radial thermal conductivities of yarns. Based on extensive simulation data, an empirical equation is proposed for the rapid prediction of the effective thermal conductivity of plain weave fabrics. Moreover, polyester, cotton, and wool plain weave fabric samples are tested for their thermal conductivity in a vacuum environment. The predicted results from the empirical equation proposed in this study exhibit a deviation of less than 6 % when compared to experimental measurements. This study can provide valuable insights for the design of plain weave fabrics used in aerospace insulation materials.

Flexible, Thermally Stable, and Ultralightweight Polyimide-CNT Aerogel Composite Films for Energy Storage Applications.

Polyimide (PI) aerogels are promising in various fields of application, ranging from thermal insulators to aerospace. However, they are typically in the form of a bulk monolith, which suffers from a lack of conformability and drapability. Moreover, their electrical conductivity is limited, and they mainly display an insulative behavior. These shortcomings can limit the applications of PI aerogels in energy storage systems, which require ultralightweight flexible conductive films, which at the same time offer high thermal stability, ultralow density, and high surface area. To overcome these obstacles, the present study reports the fabrication of PI-carbon nanotube (PI-CNT) aerogel composite films with varying CNT content prepared through a sol-gel preparation method, followed by a supercritical drying procedure. Compared to pristine PI aerogels, which displayed a large shrinkage and density of 18.3% and 0.12 g cm-3, respectively, the incorporation of only 5 wt % CNTs resulted in a significant reduction of both shrinkage and density to only 11.5% and 0.10 g cm-3, respectively. This suggests the importance of CNTs in improving the dimensional stability of aerogels and creating a robust network. Further characterizations showed that incorporation of 5 wt % CNTs also resulted in the highest pore volume (1.25 cm3 g-1), highest surface area (324 m2 g-1), highest real permittivity (80), highest electrical conductivity (3 × 10-1 S m-1), and ultrahigh service temperature (575 °C). It was also shown that the aerogel films can withstand a large degree of bending, can be twisted, and can be fully rolled with no obvious cracks propagated in the structure. The combined outstanding properties of the developed aerogel composite films make them promising potential candidates for supercapacitor electrodes. Therefore, the electrochemical performance of the devices based on aerogel electrodes was further studied. The device demonstrated a high energy density of 2.6 Wh kg-1 at a power density of 303.8 W kg-1. The total capacitance after 5000 cycles was 91.8% of the initial capacitance, which indicated excellent stability and durability of the device. Overall, this work provides a facile yet effective methodology for the development of high-performance aerogel materials for energy storage applications.

Integrating V-doped CoP on Ti3C2Tx MXene-incorporated hollow carbon nanofibers as a freestanding positrode and MOF-derived carbon nanotube negatrode for flexible supercapacitors

Novel architectural electrode materials that are freestanding and exhibit improved electrochemical performances in flexible asymmetric supercapacitors are urgently needed; however, designing these materials is challenging. Herein, a Ti3C2TX MXene-aligned hollow carbon fiber (MX/HCF) is engineered and vanadium-doped cobalt phosphide nanorod arrays are grown on it (V-CoP@MX/HCF) and applied for supercapacitor positrode. V doping modulates the surface structure and electronic environment of CoP nanorods grown over conductive and flexible MX/HCFs. As expected, the optimized V-CoP@MX/HCF exhibits a better electrochemical performance (1896.8Fg−1) than that of CoP@MX/HCF and CoP@HCF. For the negative electrode, zeolitic imidazolate framework-67 (ZIF-67) grown on electrospun polyacrylonitrile (PAN) fibers is converted to cobalt nanoparticle-encapsulated nitrogen-doped carbon nanotubes at carbon nanofibers (Co-CNT@CNF) by a simple heat treatment without the burden of external catalysts and reducing gases. The as-designed freestanding Co-CNT@CNF delivers a specific capacitance of 405.5Fg−1 with superior cycling stability. A flexible asymmetric supercapacitor (V-CoP@MX/HCF//Co-CNT@CNF) is designed that unveil remarkable electrochemical properties, such as a high energy density of 72.4 Wh kg−1 at 800.12 W kg−1 and good capacitance retention (91.4 %) after 10,000 charge/discharge cycles. Furthermore, the device can maintain a consistent performance regardless of the bending degree. More importantly, this work provides new opportunities to rationally design novel freestanding cathodes and anodes for high-performance flexible asymmetric supercapacitors.

Bio-Inspired Hydrogel-Elastomer Actuator with Bidirectional Bending and Dynamic Structural Color.

In nature, some creatures can change their body shapes and surface colors simultaneously to respond to the external environments, which greatly inspired researchers in the development of color-tunable soft actuators. In this work, we present a facile method to prepare a smart hydrogel actuator that can bend bidirectionally and change color simultaneously, just like an octopus. The actuator is fabricated by elastomer/hydrogel bilayer and the hydrogel layer was decorated with thermoresponsive microgels as the photonic crystal blocks. Compared with the previously reported poly(N-isopropylacrylamide) hydrogel-based bilayer hydrogel actuators, which are generally limited to one-directional deformation, the elastomer/hydrogel bilayer actuator prepared in our work exhibits unique bidirectional bending behavior in accordance with the change of structural color. The bending degrees can be changed from -360° to 270° in response to solution temperatures ranging from 20 °C to 60 °C. At the same time, the surface color changes from red to green, and then to blue, covering the full visible light spectrum. The bending direction and degree of the hydrogel actuator can easily be adjusted by tuning the layer thickness ratio of the elastomer/hydrogel or the composition of the hydrogel. The color-tunable hydrogel-elastomer actuator reported in this work can achieve both programmable deformations and color-changing highly resembling the natural actuating behaviors of creatures.

Study of flexible metasurface with gold rod resonators on ploymide substrate in terahertz waveband

A flexible metasurface based on gold rod resonator arrays on a polyimide substrate in the terahertz band is presented. Four different resonator structures with various azimuth angle were designed and investigated. Experimental results demonstrate that the azimuth angle of the gold rod resonators have a significant impact on the terahertz waves under different polarization conditions. Experimental studies on the bending performance reveal that the spectral modulation characteristics of the flexible metasurface is robust within a degree of bending. In addition, the effect of the incident angle on the resonant peaks was investigated, and the redshift of the high-frequency resonant peak was found as the incident angle increases.

A reactive transport model for in-situ leaching of weathered crust elution-deposited rare earth ores using ammonium sulfate

This study presents a reactive transport model for the in-situ recovery of weathered crust elution-deposited rare earth ores and aims to provide predictive and optimization techniques for rare earth recovery. The model integrates Kerr's selection coefficient, dynamic reversible shrinking core model, and transport model to capture the dynamics of leaching fraction, rare earth elements (REEs), and exchangeable ions during in-situ leaching. The proposed model was validated through bench-scale equilibrium, kinetic, and column experiments, as well as numerical simulation. The results indicate that the deviation from using a single selection coefficient (referred to as 4.26 L2 mol−2 in this study) for modeling is acceptable. Both Darcy velocity and concentration of leaching solution mainly affect the peak value and bending degree of the post-peak leaching curve. Optimal cessation of leaching solution injection, such as substituting water after the peak of the leaching curve, enables effective conservation of leaching solution and reduction of environmental pollution. Differences of at least two orders of magnitude were observed between dynamic parameters derived from kinetic experiments (1.46 and 4.34 L mol−1 min−1) and those obtained from column experiments (2.60 × 10−3 and 1.71 × 10−2 L mol−1 min−1). This finding carries substantial implications for in-situ recovery and mineralization processes, highlighting the need for further investigation at the pore scale.

Construction of amorphous V2O5@Ti3C2Tx synergistic heterostructure on 3D carbon cloth substrate by a self-assembled strategy towards high-performance aqueous Zn-ion batteries

The emerging aqueous Zn-ion batteries (ZIBs) with their low price and inherent safety are showing strong competitiveness in the energy storage field. In this work, layer-by-layer stacked amorphous V2O5@Ti3C2Tx heterostructures anchored on three-dimensional carbon cloth (3D CC), synthesized by annealing process and subsequent in-situ electrochemical induction, are reported as high capacity and stable cathode for ZIBs. In this composite cathode, amorphous V2O5@Ti3C2Tx synergistic heterostructure provides isotropic Zn2+ migration channels and rapid electron transfer kinetics, while the 3D CC substrate can ensure that the bulk phase in the electrode material is also utilized to maximize the synergistic effect. As a result, the CC/a-V2O5@Ti3C2Tix cathode achieves a high specific capacity of 567 mAh/g at 0.1 A/g, a satisfactory rate performance of 213 mAh/g at 10 A/g, together with a long cycle life of 96.2 % capacity retention after 2000 cycles. Ex-situ characterizations show that the CC/a-V2O5@Ti3C2Tx cathode undergoes a highly reversible Zn2+/H+ co-intercalation/deintercalation mechanism during the discharge/charging process. In addition, based on the CC/a-V2O5@Ti3C2Tx cathode, the assembled flexible ZIB can operate properly under different bending degrees, showing its practicality in flexible devices. This work provides insight into the rational design of cathode materials with high Zn-storage performance.

Efficient Photocatalytic Reduction of Hexavalent Chromium by BiVO4-Decorated MXene Photocatalysts and Their Charge Carrier Dynamics.

The synergistically MXene (Ti3C2Tx) co-catalyst-decorated BiVO4-based heterostructured photocatalysts have been synthesized by a hydrothermal approach with varied loading concentrations of MXene (Ti3C2Tx) to drive the hexavalent chromium reduction efficiently. The formation of the heterostructured photocatalyst was confirmed by the appearance of X-ray diffraction (XRD) peaks corresponding to the monoclinic BiVO4 phase and MXene (Ti3C2Tx) and also the antisymmetric (834 cm-1) and symmetric stretching (715 cm-1) of tetrahedral VO4 and D (1330 cm-1) and G (1570 cm-1) bands corresponding to MXene (Ti3C2Tx) in the Raman spectrum. The worm-like structures of BiVO4 nanocrystals grew onto the lamellar sheets of MXene (Ti3C2Tx), as shown by field emission scanning electron microscopy (FESEM), and has an increased surface area of 15.62 m2g-1 in the case of BVO-20-TC. X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of V5+ and Ti3+states, and the uniform distribution of BiVO4 nanocrystals over lamellar sheets of MXene (Ti3C2Tx) is evident from energy-dispersive X-ray (EDX) analysis. The ultraviolet-diffuse reflectance spectroscopy (UV-DRS) spectra suggest a decrease in the band gap energy of BVO-20-TC to 2.335 eV, promoting a higher degree of visible light harvesting. Upon optimization, by varying the pH, the amount of the photocatalyst, and the concentration of Cr(IV), BVO-20-TC exhibits the highest photocatalytic efficiency (96.39%) while using a Cr(VI) concentration of 10 ppm at pH 2 and 15 mg of the photocatalyst, and the photoreduction of Cr(VI) to Cr(III) follows the pseudo-first-order reaction. The decrease in the PL intensity in BVO-20-TC reveals a faster transfer of electrons from MXene (Ti3C2Tx) to BiVO4. Further, the higher degree of band bending at the BiVO4/MXene (Ti3C2Tx) heterojunction, revealed from the Mott-Schottky analysis, facilitates efficient charge transfer and eventually faster and efficient photoreduction of Cr(VI) to Cr(III). The reusability and stability test undertaken for BVO-20-TC reveals that even after five cycles, the Cr (VI) photoreduction efficacy is retained. This work provides insights into photoreduction of Cr (VI) by using such heterostructures.

Scale Effect of a Kappel Tip-Rake Propeller

In this paper, the scale effect of Kappel tip-rake propellers with different end plate designs was studied using computational fluid dynamics. Given the base size of the mesh and the appropriate numerical model for the determined simulation, the open-water performance of three Kappel propellers with different bending degrees of the end plate at different scales was calculated. Comparing the scale effect of these propellers, the scale effect of the torque coefficient of a Kappel propeller is more intense than that of the conventional propeller. In addition, the scale effect of the torque coefficient is strong when the bending degree of the end plate increases, dwarfing the scale effect on the thrust coefficient. Following the research on the scale effect of the wake field for the Kappel propeller, the laws that reveal the influence of the scale on the wake field were summarized; that is, the high-speed zone in the wake relatively expands with the increase of the scale in company with a trend of tip cross flow. The research reveals the basic variation trend and rule of the open-water performance and wake distribution for the Kappel propeller under different scales within the Reynolds number range of 4.665×105−8.666×107 considering γ transition, as well as the characteristic differences between the Kappel propellers with different end plate designs, which will be of great significance to its optimization design and application to marine vehicles of different scales.