Maximum Density Research Articles

Membraneless Micro Redox Flow Battery: From Vanadium to Alkaline Quinone

First proof‐of‐concept of a membraneless micro redox flow battery with an automated closed‐loop control, using micro actuators and micro sensors, during charge‐discharge continuous operation in recirculation mode is presented in this work. A maximum value of 60 % State of Charge with commercial Vanadium electrolyte, monitored via online spectrometry, is achieved, with a maximum discharge current density of 60 mA/cm2, and a discharge volumetric capacity of 21.5 Ah/L. Next, cycling tests show a decrease in coulombic efficiency of 0.5 % per cycle, and capacity loss. To overcome some drawbacks encountered with Vanadium, an alkaline quinone electrolyte is used instead in the membraneless micro redox flow battery. Using this new electrolyte, sixty continuous cycles are performed showing a decrease in coulombic efficiency of 0.6 % per cycle, and a capacity loss of only 1.2 % per cycle. The performances obtained outshine previous literature results. The highest energy efficiency obtained for a membraneless micro redox flow battery is presented here with alkaline quinone being 28.9 %. Cycling a membraneless micro redox flow battery is achieved for the first time, suggesting improvement of its performance as a future work so that metrics of conventional redox flow batteries are achieved.

Revealing the mechanism of superimposing ultrasonic vibration on microstructure evolution in friction stir welding by multi-physical multi-scale simulation

Ultrasonic vibration-enhanced friction stir welding (UVeFSW) is a promising joining method for aluminum‑lithium (Al-Li) alloy. However, directly observing the microstructural evolution in UVeFSW only by experimental methods is still a challenge. The mechanism of ultrasonic vibration (UV) on the microstructure evolution during FSW of Al-Li alloy remains unrevealed. In this study, a multi-physical multi-scale model was developed by coupling the finite element (FE) method and the Monte Carlo (MC) method to quantitatively study the impact of superimposing UV on the microstructure evolution in FSW. The preheating effect, acoustoplastic effect and residual hardening effect of UV were all considered in the model. Welding thermal processes, microstructure evolution of the material on the advancing side (AS) and in the center of the weld were quantitatively analyzed. And dislocation density and grain size in UVeFSW and FSW of Al-Li alloy were compared. Temperature field simulation results show that superimposing UV on FSW has a certain preheating effect in front of the tool. Microstructure simulation results show that the main effect of UV on microstructure evolution is the dynamic recrystallisation (DRX) process, where the maximum dislocation density in the weld nugget zone (WNZ) increases from 2.49 × 1013 m−2 to 3.49 × 1013 m−2 after superimposing UV, leading to an increase in the plastic deformation stored energy. Thereby, the driving force for nucleation and DRX increases, resulting in more nuclei in the WNZ, together with an increase in the width of the WNZ. Superimposing ultrasonic vibration in FSW can significantly refine the grain size by enhancing the activity and multiplication of dislocation in the UVeFSW of Al-Li alloy. The model is validated by the experimental results.

Hole scavenger effect on hexagonal ZnO nanostructures decorated with SnO2 nanoparticles for generating high current densities via photoelectrochemical activity

This study investigated the effects of the heterostructure and interface kinetics on the photocurrents generated by ZnO-coupled SnO2 nanostructures. Electrochemical impedance spectroscopy was utilized to understand the nanostructure heterostructure and interface charge kinetics in a 0.1 M NaOH under a ON/OFF state; the lowest charge kinetic resistance of 370.84 Ω was attained for ZnO sample decorated with SnO2 particles in the light state, which is ten times lower than that of ZnO structures, with a current density of 0.94 mA cm−2. In addition, the effect of the applied potential on the charge production of all the electrodes was examined at an applied voltage of 0.55 V vs. reference electrode, which showed the maximum generation of induced-current density for ZnO nanostructures decorated with SnO2 particles compared with other pristine electrodes. Furthermore, the hole scavenger effect on the interface kinetics and photocurrent generation for all the photoelectrodes was investigated under similar conditions, such as without a scavenger and in the same electrolyte. All electrodes in the presence of the scavenger exhibited better resistance, charge transfer kinetics, and photocurrent densities than the electrodes without a scavenger. The maximum current density of 8.96 mA cm−2 was attained for ZnO nanostructures decorated with SnO2 nanoparticles. This was higher compared with other pristine electrodes with scavengers, owing to better charge migration and reduced recombination due to the hole scavenger.

Friendly Environmental Strategies to Recycle Zinc-Carbon Batteries for Excellent Gel Polymer Electrolyte (PVA-ZnSO4-H2SO4) and Carbon Materials for Symmetrical Solid-State Supercapacitors.

In this report, we introduce a novel idea to prepare a redox additive in a gel polymer electrolyte system of PVA-ZnSO4-H2SO4 based on zinc-carbon battery recycling. Here, zinc cans from spent zinc-carbon batteries are dissolved completely in 1 M H2SO4 to obtain a redox additive in an aqueous electrolyte of ZnSO4-H2SO4. Moreover, carbon nanoparticles and graphene nanosheets were synthesized from carbon rod and carbon powder from spent zinc-carbon batteries by only one step of washing and electrochemical exfoliation, respectively, which have good electrochemical capability. The three-electrode system using a ZnSO4-H2SO4 electrolyte with carbon nanoparticles and graphene nanosheets as working electrodes shows high electrochemical adaptability, which points out its promising application in supercapacitor devices. Thus, the symmetrical solid-state supercapacitor devices based on the sandwich structure of graphene nanosheets/PVA-ZnSO4-H2SO4/graphene nanosheets illustrated the highest energy density of 39.17 W h kg-1 at a power density of 1700 W kg-1. While symmetrical devices based on carbon nanoparticles/PVA-ZnSO4-H2SO4/carbon nanoparticles exhibited a maximum energy density of 35.65 W h kg-1 at a power density of 1700 W kg-1. Moreover, these devices illustrate strong durability after 5000 cycles, with approximately 90.2% and 73.1% remaining, respectively. These results provide a promising strategy for almost completely recycling zinc-carbon batteries, one of the most popular dry batteries.

In Situ Growth of Amorphous MnO2 on Graphite Felt via Mild Etching Engineering as a Powerful Catalyst for Advanced Vanadium Redox Flow Batteries.

Owing to the advantages of low cost, high safety, and a desirable cycling lifetime, vanadium redox flow batteries (VRFBs) have attracted great attention in the large-scale energy storage field. However, graphite felts (GFs), widely used as electrode materials, usually possess an inferior catalytic activity for the redox reaction of vanadium ions, largely limiting the energy efficiency and rate performance of VRFBs. Here, an in situ growth of amorphous MnO2 on graphite felt (AMO@GF) was designed for application in VRFBs via mild and rapid etching engineering (5 min). After the etching process, the graphite felt fibers showed a porous and defective surface, contributing to abundant active sites toward the redox reaction. In addition, formed amorphous MnO2 can also serve as a powerful catalyst to facilitate the redox couples of VO2+/VO2+ based on density functional theoretical (DFT) calculations. As a result, the VRFB using AMO@GF displayed an elevated energy efficiency and superior stability after 2400 cycles at 200 mA cm-2, and the maximum current density can reach 300 mA cm-2. Such a high-efficiency and convenient design strategy for the electrode material will drive the further development and industrial application of VRFBs and other flow battery systems.

Annealing Process on Metal–Oxide–Semiconductor Channel Properties for Quasivertical GaN‐on‐Sapphire Trench Metal–Oxide–Semiconductor Field‐Effect Transistor

Quasivertical gallium nitride trench‐gate metal–oxide–semiconductor field‐effect transistors with different etch radio frequency power and the impact of the order of annealing process in tetramethylammonium hydroxide wet treatment have been fabricated and studied. The high‐power device has a threshold voltage of 5.3 V and a maximum saturation current density of 552 A cm−2, whereas the low‐power device has a threshold voltage of 4.5 V and a maximum saturation current density of 650 A cm−2. However, the low‐power device has more severe off‐state leakage due to more fixed charges and defects on the device surface. Furthermore, the annealing process serves as an additional step before wet treatment. Scanning electron mircoscope image indicates that annealing at high temperatures prior to etching can eliminate surface oxide and redistribute surface imperfections, resulting in a smoother sidewall morphology. The relationship between temperature and mobility confirms the impact of the crystal surface feature on device performance.

In-depth analysis of VARTM-based solid-state supercapacitors utilizing CNT-dispersed cobalt-bismuth-samarium ternary hydroxide on woven carbon fiber for enhanced energy storage

Multi-metal hydroxides possess unique physical and chemical properties, making them promising candidates for supercapacitor working electrodes. Enhancing their electrochemical performance can be achieved through a combination with carbon materials. In this study, we synthesized a composite material by hydrothermally dispersed 4, 6, and 10 wt% carbon nanotubes (CNT) into ternary cobalt-bismuth-samarium hydroxide (CoBiSm-TOH). These nanocomposites were employed as the material for the working electrode in a supercapacitor. The findings reveal that at 1.5 A/g, the specific capacitance of CNT3@CoBiSm-TOH, using a three-electrode system, was found to be 852.91 F/g, higher than that of CoBi-BOH, CoBiSm-TOH, CNT1@CoBiSm-TOH and CNT5@CoBiSm-TOH—measuring 699.69, 750.34, 789.54 and 817.79 F/g, respectively. Moreover, CNT3@CoBiSm-TOH electrodes exhibited a capacitance retention of around 88% over 10,000 cycles. To demonstrate practical applicability, CNT3@CoBiSm-TOH was grown on woven carbon fiber (WCF), and a solid-state supercapacitor device was developed using the VARTM (vacuum-assisted resin transfer molding). This device displayed a specific capacitance of 272.67 F/g at 2.25 A/g. Notably, it achieved a maximum energy density of 53.01 Wh/kg at a power density of 750 W/kg and sustained excellent cycle stability over 50,000 cycles, maintaining 70% of its initial capacitance. These results underscore the importance of interfacial nanoengineering and provide crucial insights for the development of future energy storage devices.

Fabrication of binary metal–organic frameworks of Ni–Mn@ZIFs(Cox·Zn1−xO) decorated on CF/CuO nanowire for high-performance electrochemical pseudocapacitors

Herein, metal–organic frameworks (MOFs) derived nanoflower-like based binary transition metal (Ni–Mn) are successfully fabricated by a simple synthesis method. The fabricated nanoflower-like structure displays a unique nanoflower-like architecture and internal porous channels constructed by MOF coated on CuO/CF/ZIFs (Cox·Zn1−xO) substrate, which is beneficial for the penetration of electrolyte and electron/ion transportation. The as-prepared CF/CuO/ZIFs (Cox·Zn1−xO)@BMOF(Ni–Mn) electrode materials present significant synergy among transition metal ions, contributing to enhanced electrochemical performances. The as-prepared CF/CuO/ZIFs (Cox·Zn1−xO)@BMOF(Ni–Mn) hybrid nanoflower-like display a high specific capacity of 1249.99 C g−1 at 1 A g−1 and the specific capacitance retention is about 91.74% after 5000 cycles. In addition, the as-assembled CF/CuO/ZIFs (Cox·Zn1−xO)@BMOF(Ni–Mn)//AC asymmetric supercapacitor (ASC) device exhibited a maximum energy density of 21.77 Wh·kg−1 at a power density of 799 W kg−1, and the capacity retention rate after 5000 charge and discharge cycles was 88.52%.

Nomogram for the preoperative prediction of Ki-67 expression and prognosis in stage IA lung adenocarcinoma based on clinical and multi-slice spiral computed tomography features

ObjectiveThis study developed and validated a nomogram utilizing clinical and multi-slice spiral computed tomography (MSCT) features for the preoperative prediction of Ki-67 expression in stage IA lung adenocarcinoma. Additionally, we assessed the predictive accuracy of Ki-67 expression levels, as determined by our model, in estimating the prognosis of stage IA lung adenocarcinoma.Materials and methodsWe retrospectively analyzed data from 395 patients with pathologically confirmed stage IA lung adenocarcinoma. A total of 322 patients were divided into training and internal validation groups at a 6:4 ratio, whereas the remaining 73 patients composed the external validation group. According to the pathological results, the patients were classified into high and low Ki-67 labeling index (LI) groups. Clinical and CT features were subjected to statistical analysis. The training group was used to construct a predictive model through logistic regression and to formulate a nomogram. The nomogram’s predictive ability and goodness-of-fit were assessed. Internal and external validations were performed, and clinical utility was evaluated. Finally, the recurrence-free survival (RFS) rates were compared.ResultsIn the training group, sex, age, tumor density type, tumor-lung interface, lobulation, spiculation, pleural indentation, and maximum nodule diameter differed significantly between patients with high and low Ki-67 LI. Multivariate logistic regression analysis revealed that sex, tumor density, and maximum nodule diameter were significantly associated with high Ki-67 expression in stage IA lung adenocarcinoma. The calibration curves closely resembled the standard curves, indicating the excellent discrimination and accuracy of the model. Decision curve analysis revealed favorable clinical utility. Patients with a nomogram-predicted high Ki-67 LI exhibited worse RFS.ConclusionThe nomogram utilizing clinical and CT features for the preoperative prediction of Ki-67 expression in stage IA lung adenocarcinoma demonstrated excellent performance, clinical utility, and prognostic significance, suggesting that this nomogram is a noninvasive personalized approach for the preoperative prediction of Ki-67 expression.

Improving Soft Subgrade Stability Using a Novel Sustainable Activated Binder Derived from By-Products

Soft soil concerns, due to high compressibility and low bearing capacity, prompted an investigation into stabilizing clay soil. Traditionally, binder including cement or lime has been used as stabilizers though a current requirement of alternatives is stem from environmental concerns. The study focused on the viability of using a novel binary activated blended binder composed of environmentally friendly materials, namely ground granulated blast furnace slag (GGBS) activated by cement kiln dust (CKD). The experimental work included investigating the impact of the developed binders on the Atterberg limits, standard Proctor compaction, California Bearing Ratio (CBR), unconfined compressive strength (UCS), and field-emission scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy. CBR tests were conducted after 7 days of curing or soaking, while UCS and SEM analyses were conducted after 7 and 28 days of curing. A fixed binder ratio of 9% was maintained, with GGBS blended at 25%, 50%, and 75% with CKD. For comparison, samples of untreated and treated soils with unary binders from GGBS and CKD were also prepared. Results indicated that activated binders notably decreased soil plasticity and maximum dry density, while elevating optimum moisture content, CBR, and UCS, especially in later stages of treated soil and unary GGBS binder. Unary CKD binder exhibited a similar trend to activated binders. The activating of 25% GGBS with 75% CKD provided the optimum binder which increased the mechanical strengths by about 6 times than untreated soil. SEM revealed substantial formations of C-S-H and C-A-H gel, along with ettringite, intensifying with time. This research provides viable outcomes for stabilizing clay soil using environmentally friendly binders, demonstrating significant improvements in soil properties, particularly when using the binary activated blended binder consisting of GGBS and CKD.Graphical

Modeling and analysis of a novel 6-DOF magnetic levitation system with experimental verification

To improve the uniformity of magnetic flux and increase the stroke of the magnetic levitation system, this paper designs a novel 6-DOF magnetic levitation system and proposes an improved novel Halbach array. First, a repulsive passive magnetic bearing is utilized to provide levitation force, leading to a noticeable reduction in levitation power consumption. Then, a magnetic circuit model for the magnetic levitation system is established, and the improved novel Halbach array is optimized based on this model. Next, the stable levitation model and measurement model for the system are established, and the magnetic field distribution and magnetic bearing stiffness are analyzed. Results indicated an increase of 0.1[Formula: see text]T in the maximum magnetic flux density, accompanied by an improvement in the uniformity of magnetic flux. Additionally, there is an enhancement of 10% in magnetic bearing stiffness. Finally, a prototype of the system is constructed, and the stable levitation simulation and experiment of the actuator are conducted with this system. The maximum levitation absolute displacement error obtained by simulation is about 655[Formula: see text]nm, and the experimental results exhibited a maximum levitation absolute displacement error of approximately 750 nm for the system, confirming the effectiveness of the proposed modeling method.

Exploring the post-harvest ‘window of vulnerability’ to landslides in New Zealand steepland plantation forests

Nature-based solutions (NbS) are actions to address societal problems. They are similar to soil and water bioengineering (SWB), where trees and forests are used to mitigate natural hazards. However, NbS can have unintended consequences.Forest-based NbS may involve the enhancement, rehabilitation or restoration of natural forests or planting of trees and forests to provide a range of services including the production of timber and wood. In New Zealand, planted steepland forests have been widely used as NbS for erosion control. While intact, these forests provide various beneficial ecosystem services. However, if these forests are harvested, there is a period of up to 6–‍8 years following clear-fell harvesting, known as the ‘window of vulnerability' (WoV) when the landscape is susceptible to rainfall-induced landslides. During this time, the combination of declining root strength and changes in soil hydrology can lead to shallow landslides, especially during heavy storms.This study focuses on three questions: determining whether there is a time within the WoV when susceptibility to rainfall-induced landslides, expressed as landslide density, reaches a maximum; are such landslides related to forestry infrastructure; and are those landslides connected to the stream network. We examined three areas in New Zealand (Tolaga Bay, Marlborough, and Tasman) where exceptional rain events triggered thousands of landslides on forest land harvested in the years immediately preceding those events. Using a range of high-resolution satellite imagery, we manually mapped rainfall-induced landslides and identified those due to the rain events.The maximum landslide number and density occurred on land harvested 1–4 years (and on average 2–3 years) before the event and varied slightly for each study area. Landslides also occurred in areas with trees up to harvest age of about 30 years and on areas with different vegetation covers, i.e., mature indigenous forests, pasture, scrub, etc. There were fewer landslides associated with forest infrastructure such as roads and landings than triggered on clearcut slopes. On average across the three study regions, about half the landslides were connected to streamlines, and so were able to deliver sediment and woody debris.Better information on susceptibility to rainfall-induced landslides following forest removal may help forest managers and regulators understand this hazard and what can (and cannot) be done to mitigate events which often result in ‘disastrous’ off-forest impacts as observed in New Zealand in recent years.

Laser-driven ion and electron acceleration from near-critical density gas targets: Towards high-repetition rate operation in the 1 PW, sub-100 fs laser interaction regime

Ion acceleration from gaseous targets driven by relativistic-intensity lasers was demonstrated as early as the late 1990s, yet most of the experiments conducted to date have involved picosecond-duration, Nd:glass lasers operating at low repetition rate. Here, we present measurements on the interaction of ultraintense (≈1020Wcm−2, 1 PW), ultrashort (≈70fs) Ti:Sa laser pulses with near-critical (≈1020cm−3) helium gas jets, a debris-free targetry with the potential for future compatibility with high (≈1 Hz) repetition rate operation. We provide evidence of α particles being forward accelerated up to ≈2.7−MeV energy with a total flux of ≈1011sr−1 as integrated over >0.1−MeV energies and detected within a 0.5−mrad solid angle. We also report on on-axis emission of relativistic electrons with an exponentially decaying spectrum characterized by a ≈10−MeV slope, i.e., five times larger than the standard ponderomotive scaling. The total charge of these electrons with energy above 2 MeV is estimated to be of ≈1nC, corresponding to ≈0.1% of the laser drive energy. In addition, we observe the formation of a plasma channel, extending longitudinally across the gas density maximum and expanding radially with time. These results are well captured by large-scale particle-in-cell simulations, which reveal that the detected fast ions most likely originate from reflection off the rapidly expanding channel walls. The latter process is predicted to yield ion energies in the MeV range, which compare well with the measurements. Finally, direct laser acceleration is shown to be the dominant mechanism behind the observed electron energization. Published by the American Physical Society 2024

Investigating the influence of oxygen-functionalized graphene nanosheets as an efficient multifunctional material for supercapacitor and electrocatalytic water splitting applications

Graphene oxide (GO) has received great research attention to develop its efficiency in electrochemical applications, particularly supercapacitor (SC) and water splitting systems. However, the presence of various oxygen moieties in GO drastically reduces the utilization of the material for commercial usages. In this work, we demonstrate the use of different sources to reduce graphene oxide (GO) nanosheets. The partially reduced GO not only improves the electronic conductivity but also boosts the interaction between the sp2- and sp3-hybridized carbon atoms. Benefiting from the partial reduction process, RGO is applied for the SC test in the three-electrode system and reveals a specific capacitance of 151.1 F g−1 at 1 A g−1 with a long cycle life. Furthermore, the asymmetric solid-state device can also be constructed from an M-GO cathode with an activated carbon anode, which displays a specific capacitance of 54.4 F g−1 at 1 A g−1, with a maximum energy density of 19.3 W h kg−1. Besides, the electrochemical water splitting performance of the partially reduced GO in KOH solution was also explored, confirming the effectiveness of the reduction process. This work highlights the successful preparation of RGO nanosheets, which may open a new route to constructing high-performance energy storage and conversion devices.

Sweet corn phytoglycogen dendrimers as a lyoprotectant for dry-state protein storage.

Protein biotherapeutics typically require expensive cold-chain storage to maintain their fold and function. Packaging proteins in the dry state via lyophilization can reduce these cold-chain requirements. However, formulating proteins for lyophilization often requires extensive optimization of excipients that both maintain the protein folded state during freezing and drying (i.e., "cryoprotection" and "lyoprotection"), and form a cake to carry the dehydrated protein. Here we show that sweet corn phytoglycogens, which are glucose dendrimers, can act as both a protein lyoprotectant and a cake-forming agent. Phytoglycogen (PG) dendrimers from 16 different maize sources (PG1-16) were extracted via ethanol precipitation. PG size was generally consistent at ~70-100 nm for all variants, whereas the colloidal stability in water, protein contaminant level, and maximum density of cytocompatibility varied for PG1-16. 10 mg/mL PG1, 2, 9, 13, 15, and 16 maintained the activity of various proteins, including green fluorescent protein, lysozyme, β-galactosidase, and horseradish peroxidase, over a broad range of concentrations, through multiple rounds of lyophilization. PG13 was identified as the lead excipient candidate as it demonstrated narrow dispersity, colloidal stability in phosphate-buffered saline, low protein contaminants, and cytocompatibility up to 10 mg/mL in NIH3T3 cell cultures. All dry protein-PG13 mixtures had a cake-like appearance and all frozen protein-PG13 mixtures had a Tg' of ~ -26°C. The lyoprotection and cake-forming properties of PG13 were density-dependent, requiring a minimum density of 5 mg/mL for maximum activity. Collectively these data establish PG dendrimers as a new class of excipient to formulate proteins in the dry state.

Iron Sulfide Microspheres Supported on Cellulose-Carbon Nanotube Conductive Flexible Film as an Electrode Material for Aqueous-Based Symmetric Supercapacitors with High Voltage.

Nanostructured iron disulfide (FeS2) was uniformly deposited on regenerated cellulose (RC) and oxidized carbon nanotube (CNT)-based composite films using a simple chemical bath deposition method to form RC/CNT/FeS2 composite films. The RC/CNT composite film served as an ideal substrate for the homogeneous deposition of FeS2 microspheres due to its unique porous architecture, large specific surface area, and high conductivity. Polypyrrole (PPy), a conductive polymer, was coated on the RC/CNT/FeS2 composite to improve its conductivity and cycling stability. Due to the synergistic effect of FeS2 with high redox activity and PPy with high stability and conductivity, the RC/CNT/FeS2/PPy composite electrode exhibited excellent electrochemical performance. The RC/CNT/0.3FeS2/PPy-60 composite electrode tested with Na2SO4 aqueous electrolyte could achieve an excellent areal capacitance of 6543.8 mF cm-2 at a current density of 1 mA cm-2. The electrode retained 91.1% of its original capacitance after 10,000 charge/discharge cycles. Scanning electron microscopy (SEM) images showed that the ion transfer channels with a pore diameter of 5-30 μm were formed in the RC/CNT/0.3FeS2/PPy-60 film after a 10,000 cycle test. A symmetrical supercapacitor device composed of two identical pieces of RC/CNT/0.3FeS2/PPy-60 composite electrodes provided a high areal capacitance of 1280 mF cm-2, a maximum energy density of 329 μWh cm-2, a maximum power density of 24.9 mW cm-2, and 86.2% of capacitance retention after 10,000 cycles at 40 mA cm-2 when tested at a wide voltage window of 1.4 V. These results demonstrate the greatest potential of RC/CNT/FeS2/PPy composite electrodes for the fabrication of high-performance symmetric supercapacitors with high operating voltages.

Exploration of improved, roller-based spreading strategies for cohesive powders in additive manufacturing via coupled DEM-FEM simulations

Spreading of fine (D50 ≤20μm) powders into thin layers, such as required by layer-wise additive manufacturing (AM) processes, typically requires a mechanism such as a roller that provides adequate shear and compression to overcome the cohesive forces between particles. We explore improved, roller-based spreading strategies for highly cohesive powders using an integrated discrete element-finite element (DEM-FEM) framework. We find that optimal roller-based spreading, quantified by maximum packing density and uniformity of layer thickness, relies on a combination of surface friction of the roller and roller kinematics, e.g., counter-rotation or angular oscillation, that impart sufficient kinetic energy to break cohesive bonds between powder particles. However, excess rotation speed (or shear stress) can impart excessive kinetic energy to the powder causing ejection of particles and a non-uniform layer, suggesting the existence of a process window of optimal spreading parameters. Interestingly, the identified optimal parameters for both investigated roller kinematics, i.e., angular velocity for counter-rotation as well as angular frequency and amplitude for rotational oscillation, result in a very similar range of roller surface velocities, suggesting roller surface velocity as the critical kinematic parameter. When these conditions are chosen appropriately, layers with packing fractions beyond 50% are predicted for layer thicknesses as small as ∼2 times D90 of the exemplary cohesive powder, and the layer quality is robust with respect to substrate adhesion over a 10-fold range. The latter is an important consideration given the spatially varying substrate conditions in AM due to the combination of fused/bound and bare powder regions. As compared to counter-rotation, the proposed rotational oscillation kinematics are particularly attractive because they can overcome practical issues with mechanical runout of roller mechanisms (which limit their precision).

Surface-tuning TiO2 NR photoanodes using CoOx interlayers and NiFe-LDH cocatalysts for photoelectrochemical wastewater treatment

Increasing multidrug-resistant pathogenic microbial around the world become a global problem, making it imperative to develop effective methods for bacterial inactivation in wastewater. In this study, we propose a multifunctional photoelectrochemical (PEC) system to successfully disinfect microbial cells and degrade orange (II) dyes. CoOx NP were synthesized by spin-coating onto hydrothermally synthesized TiO2 nanorod arrays followed by electrodeposited NiFe-LDH to develop the NiFe-LDH/CoOx NP-TiO2 NRs. Interestingly, spin-coated CoOx NP-TiO2 NRs exhibited a 1.5-fold enhancement in photocurrent (1.384 mA/cm2) than pristine TiO2 NRs (0.92 mA/cm2). A NiFe-layered double hydroxide (LDH) cocatalysts layer further exhibits the maximum photocurrent density of 1.64 mA/cm2 with IPCE of 84.5% at 1.0 VAg/AgCl at 380 nm. Furthermore, NiFe-LDH/CoOx-TiO2 NR photoanodes were effectually employed for photoelectrochemical bacteria disinfection and organic pollutant removals. With NiFe-LDH/CoOx-TiO2 NR, 99% (120 min) bacterial inactivation and 99% (60 min) orange II dye decomposition efficiency was achieved. Superoxide radicals (−O2•), hydroxyl radicals (HO•), and holes (h+) played a critical role in the PEC degradation systems. Due to the synergy between NiFe-LDH cocatalyst and CoOx interlayer, surface water oxidation reactions were accelerated over NiFe-LDH/CoOx NP-TiO2 NRs. The charge transport process in NiFe-LDH/CoOx NP-TiO2 NRs photoanode-based PEC system was proposed in detail.

Thiosalicylic-Acid-Mediated Coordination Structure of Nickel Center via Thermodynamic Modulation for Aqueous Ni-Zn Batteries.

Uniquely functional nanocomplexes with rich coordination environments are critical in energy storage. However, the construction of structurally versatile nanocomplexes remains challenging. In this study, a nickel-based complex with structural variations is designed via thermodynamic modulation using a dual-ligand synthesis strategy. A nickel-based nanomaterial (NiSA-SSA-160) with a large specific surface area is synthesized around the competing coordination of the host and guest molecules that differ in terms of the chemical properties of the O and S elements. Concurrently, the coordination environment of NiSA-SSA-160 is investigated via X-ray absorption fine structure spectroscopy. The thiol functional groups synergistically induced an electron-rich Ni structure, thus increasing the electron density of the central atom. The electrochemical performance of an assembled NiSA-SSA-160//Zn@CC battery is shown to improve significantly, with a maximum energy density of 0.54 mWh cm-2 and a peak power density of 49.49mW cm-2. This study provides a new perspective regarding coordination transformations and offers an idea for the design of functionally rich nanomaterials.

Microgravity analysis of periodic oscillations of heat and mass transfer of Darcy-Forchheimer nanofluid along radiating stretching surface with Joule heating effects

Reduced gravity impact on mixed convection flow plays a significant role for designing of electric-generating plants in space, unwanted effects of free convection, thermodynamic stability, space devices, surface tension and movement of nanoparticles. The novelty of present work is to find the impact of reduced gravity, Joule heating and thermal radiations on Darcy Forchheimer magnetized flow of nanofluid along the stretching porous sheet. The variable gravity is assumed as temperature dependent with maximum density and maximum density. The governing model is converted into convenient model to find physical thermo parameters. The primitive steady, real and imaginary equations are formed by using stokes and primitive transformations. To make programming algorithm in FORTRAN Lahey-90/95, the primitively terms are deduced in each equation. For tabular and numerical findings of steady velocity, temperature and concentration, the implicit form of finite difference approach is applied with Gaussian elimination method. The fluctuating skin friction, fluctuating heat transfer and fluctuating mass transfer are displayed by using steady outcomes in main formula. It is found that the magnitude of fluid velocity enhances as magnetic force, reduced gravity and Darcy Forchheimer parameter enhances. It is concluded that temperature distribution decreases as magnetic force enhances. It is noted that oscillating frequency in skin friction and heat transfer enhances as Schmidt number enhances. It is found that the maximum fluctuating layer in heat and mass transfer enhances as Prandtl number enhances.