Maximum Density Research Articles

SPATIOTEMPORAL OF NITROGEN DIOXIDE (NO2) CONCENTRATION IN THE URBAN ENVIRONMENT OF KLANG VALLEY, MALAYSIA

The high concentration of nitrogen dioxide (NO2) directly results in Klang Valley’s air quality deterioration, causing a public health risk. This study was conducted to analyse the daily-averaged and annual concentration of nitrogen dioxide (NO2) on a spatial-temporal scale at five continuous monitoring stations under the Department of Environment (DOE) in Klang Valley, namely, Klang, Shah Alam, Petaling Jaya, Kajang, and Cheras from 2000 to 2009 using Man-Kendall statistical analysis and interpolation technique in Geographic Information System (GIS). The result clearly showed that the Petaling Jaya station was identified as the most polluted compared to other stations, with an average concentration of more than 0.050 ppm every year and reaching the maximum concentration of 0.069 ppm where the mean was 0.030 in 2001. Based on the p-value derived from the Mann-Kendall statistical analysis, the Klang, Petaling Jaya, Shah Alam, and Cheras stations recorded a significant trend with p-values < 0.05 at 0.0001 and 0.020, respectively. The annual concentration of NO2 in all the stations was in the range of 0.015 to 0.04 ppm from 2004 to 2009, compared to 0.005 to 0.01 ppm from 2000 to 2003. The highest annual-averaged NO2 concentration was reported at the Petaling Jaya station between 0.035 and 0.004 ppm for all years except 2007 and 2009 when concentrations were in the 0.03 to 0.035 ppm. Notably, the Petaling Jaya station had the highest annual NO2 concentration, which ranged from 0.025 to 0.04 ppm due to emissions from motor vehicles. The major pressure on road infrastructure was recognised, mainly a lack of space to accommodate the effect of the maximum density of motor vehicles and traffic, resulting in traffic congestion in the city centre.

Understanding effects of observing affordance-driven action during motor imagery through EEG analysis.

The aim of this paper is to investigate the impact of observing affordance-driven action during motor imagery. Affordance-driven action refers to actions that are initiated based on the properties of objects and the possibilities they offer for interaction. Action observation (AO) and motor imagery (MI) are two forms of motor simulation that can influence motor responses. We examined combined AO+MI, where participants simultaneously engaged in AO and MI. Two different kinds of combined AO+MI were employed. Participants imagined and observed the same affordance-driven action during congruent AO+MI, whereas in incongruent AO+MI, participants imagined the actual affordance-driven action while observing a distracting affordance involving the same object. EEG data were analyzed for the N2 component of event-related potential (ERP). Our study found that the N2 ERP became more negative during congruent AO+MI, indicating strong affordance-related activity. The maximum source current density (0.00611 A/mm ) using Low-Resolution Electromagnetic Tomography (LORETA) was observed during congruent AO+MI in brain areas responsible for planning motoric actions. This is consistent with prefrontal cortex and premotor cortex activity for AO+MI reported in the literature. The stronger neural activity observed during congruent AO+MI suggests that affordance-driven actions hold promise for neurorehabilitation.

Architecting hydrogen-bonded and π–π conjugated MOF@NiPc networks towards enhanced energy storage

High-capacity metal–organic framework materials is constrained by their poor electron transport and unstable in aqueous. Herein, a spherical cobalt–nickel-based metal–organic framework (CoNi-MOF) micro-architecture with 18-π aromatic electron system of nickel phthalocyanine (NiPc) nanorods has been designed. In this system, intermolecular hydrogen (H) bonds between O in CoNi-MOF and H in nickel phthalocyanine (NiPc), along with longitudinal π-π stacking structure, could improve electron transport and structuralstability of MOFs. Benefiting from the 3D electron transport highways and “locking” effect of H bonds along with longitudinal π-π stacking structure, the optimized CoNi-MOF@NiPc electrode exhibits remarkable specific capacity of 807.365C g−1 at current density of 1 A/g, along with great cycling stability with 96.19 % capacity retention after 5000 cycles at 5 A/g, which is superior to the individual components. Besides, CoNi-MOF@NiPc//AC hybrid supercapacitor has been fabricated, which displays a maximum energy density of 130.68 Wh kg−1 at 962.09 W kg−1 and excellent cyclability (93.58 % capacity retention after 10,000 cycles). This study opens a new avenue for the design of organic electrodes and provides a new insight into H bond and π-π stacking structure effect toward advanced energy storage materials.

Coal-based graphitized activated carbon for solar energy powered supercapacitor IoT applications

Solar cells show promise as energy conversion gadgets, but their extended use is limited by intermittent sunlight. Self-powered solar cell integration with an electrical energy storage system could be one solution to this problem. Therefore, we have developed a coin cell supercapacitor (SC) device based on coal-based graphitized carbon materials and integrated with solar cells to assess its efficiency for energy transformation and storage for practical validity. Supercapacitor carbon electrode was developed from a naturally abundant carbon precursor i.e. low-grade coal using molasses as binder, for the fabrication of high-quality SC devices. The fabricated supercapacitor exhibits a notable 127 F g−1 specific capacitance, maintaining 92 % of its initial value for up to 10,000 charge/discharge cycles at 5 A g−1, and a maximum energy density of 70.57 Wh kg−1 and power density of 2000.17 W kg−1. In order to create a self-sustaining power pack, the SCs (4 V) are integrated with a commercial solar cell (6 V, 750 mAh). Importantly, in the presenceof natural sunlight, the solar-powered as-fabricated supercapacitor bankcan significantly power a commercial IoT module (4–6 V, 600 mAh) demonstrating its potential for successful solar-to-electric energy transformation and storage. The findings demonstrate that solar-powered coal-based SC can be explored as an incredibly rapid future-proof energy storage technology that can help reduce energy demand in the foreseeable future.

The influence of weather conditions on the formation of the winter wheat harvest according to various precursors in the arid zone of Stavropol

Relevance. The identification of agro meteorological factors that have the greatest impact on the formation of grain yields and their consideration in the improvement of agricultural technologies is an urgent task of agriculture.Methods. The research was carried out in 1972–2023 in the fields of the Prikumsk experimental breeding station in a 6-pole grain-and-grass crop rotation. The purpose of the research is to study the influence of agro meteorological conditions on the formation of the winter wheat harvest according to various precursors for the correction and adaptation of applied agricultural technologies in the arid zone of the Stavropol Territory.Results. The yield of winter wheat significantly depended on precipitation in September — October, moisture reserves by spring, total moisture availability of crops, temperature in May and was determined by the density of plants and the weight of 1000 grains. The maximum yield was formed with precipitation in September — October >117 mm, the highest density of standing (294–392 pcs/m2), spring moisture reserves in the meter soil layer and average total moisture supply for pure steam, respectively, 129–145 mm and 382 mm, occupied steam 115–135 mm and 378 mm and winter wheat 105–125 mm and 342 mm. The minimum duration of the sowing — germination period and the maximum density of standing accounted for a clean and occupied pair for the amount of precipitation for September — October (59–87), and a half-pair >117 mm. Compared with pure steam, the density of standing decreased by an average of 12,2%, the yield by 19,2%, the duration of germination increased 1.4 times, and in repeated crops by 22,6%, 45,3% and 2,7 times, respectively. The mass of 1000 grains had a significant positive relationship with the density of standing by half-steam and a negative one with the average temperature for May — June by pure steam. For half-steam and pure steam, yield is more closely related to the mass of 1000 grains (r = 0.52–0.66) than to the density of standing (r = 0.45–0.50).

Sustainability-driven application of waste steel and tyre rubber fibres as reinforcement in concrete: An optimization study using response surface methodology

Innovative use of waste materials has proven to be effective for improving concrete’s technical properties while eliminating the threat of environmental pollution. There is paucity of research regarding the combined use of Waste Steel Fibres (WSFs) and Waste Tire Rubber Fibres (WTRFs) in concrete. Thus, this study aimed to investigate the influence of WSFs and WTRFs as reinforcement in concrete and determine their optimal fractions for enhancing the concrete strength properties using Response Surface Methodology (RSM). WSFs of 0.3-1.5% with a 0.6% increment and WTRFs of 0.3-1.5% with a 0.6% increment by concrete volume as reinforcement in concrete with water-to-cement ratio (W/C) of 0.25–0.65 with 0.2 increment were designed using the Box-Behnken Design of RSM. A total of fourteen (14) concrete mixes with a design strength of 25 N/mm2 were prepared. The fresh and hardened properties (slump, density, water absorption, 7- and 28-day compressive and split tensile strengths) of concrete were determined using standard procedures. The RSM was used to evaluate the interaction between the concrete variables and identify their optimum combination which gave the peak values of responses. Furthermore, the characteristics and sustainability of the concrete under optimum variables were compared with that of the conventional concrete. The outcomes revealed that the inclusion of WSFs and WTRFs yielded concretes with maximum slump, density, water absorption and 28-day compressive and split tensile strengths of 25 mm, 2633 kg/m3, 5%, 41 N/mm2 and 4.54 N/mm2, respectively. The optimization technique showed the optimal variables combination which yielded the peak response values of WSFs (1.40%), WTRFs (0.66%) and W/C (0.54). The nominal variance with the absolute percent error of less than (9%) between the actual experimental verified results and predicted results for all the responses validates the predictability of the model. The split tensile strength and compressive strength increased by 28.33% and 48.85%, respectively at the optimum setpoint of variable with respect to the reference concrete. In addition, the WSFs and WTRFs-reinforced concrete exhibited lower embodied CO2 emission but the embodied energy and cost are slightly higher relative to conventional concrete. Nevertheless, the embodied energy of the concrete was significantly lesser than that of concrete that used individual fibers for reinforcement. Thus, the enhancement of concrete strength properties with the prospect for sustainable fibre-reinforced concrete production through the use of waste steel and tyre rubber fibres is feasible.

Unveiling optimal activity and mechanism of in situ Ni reduction Pr2Ni1-xZnxO4 anode for ammonia solid oxide fuel cells

Kinetically sluggish ammonia oxidation and interference of H2 competing with NH3 active sites will suppress the output performance of direct ammonia solid oxide fuel cell (DA-SOFC). Herein, we select Zn2+ doped into Pr2NiO4 as precursor of Pr2Ni1-xZnxO4 (PNZx) that can be destroyed and converted into Pr2O3 together with in-situ Ni reduction, realizing the redistribution of elements in reduction atmosphere. Meanwhile, the foreign Zn2+ as a low-valent element is retained in Pr2O3 lattice due to the high segregation Gibbs free energy to form Ni/Pr2-xZnxO3, which aggravates the change of Pr3+ and Pr4+, thus enhancing the oxygen vacancy concentration. The Zn2+ promotes the reduction of Ni and quenches the adsorption capacity of H2, alleviating the “hydrogen poisoning” behavior. As a result, the maximum powder density of single cell based on PNZ0.1 supported by YSZ electrolyte is 134 mW·cm−2 at 800 ℃, which is more than twice higher than that of Ni/YSZ. Various characterizations reveal that the NH3 reaction path is the synergistic occurrence of ammonia decomposition and ammonia oxidation.

Impact of CNT assimilation on binary MoO2/MoS2 hybrid for enhanced cyclic stability during charging-discharging process

Cyclic stability is a crucial metric for assessing the service lifespan of supercapacitors, as it determines the retention capacity of the electrode material. This study demonstrates the significant impact of Carbon Nanotubes (CNT) on enhancing the cyclic stability of a binary hybrid MoO2/MoS2 (MOS) electrode material, thereby improving supercapacitor performance and durability. The combination of MoO2 and MoS2 enhances capacitance due to their high surface area and electrical conductivity. Introducing CNTs into MOS significantly enhances cyclic stability and provides a crucial pathway for electrolyte ions during charging-discharging cycles, despite a minor compromise in conductivity and energy efficiency. This trade-off is justified by the substantial improvement in overall performance and durability. The materials were synthesized and deposited on Nickel foam via a hydrothermal route without any binding agent. Electrochemical tests showed specific capacitances of 2617 F/g for MOS and 2052 F/g for MOSC at a current density of 1 A/g. The MOSC system exhibited a 41.4 % increase in cyclic stability after 2000 cycles. Additionally, a symmetric coin cell device fabricated with the MOSC material demonstrated a maximum energy density of 153.41 mWh/kg and a power density of 3 kW/kg at a current density of 0.05 A/g, with a capacitive retention of 74.05 %. This underscores the potential of MOSC as a scalable electrode material for industrial energy storage applications.

Feasibility of using synthetic MRI to predict lymphatic vascular space invasion status in early-stage cervical cancer: added value to morphological MRI

To investigate the feasibility of synthetic magnetic resonance imaging (syMRI) in predicting the lymphatic vascular space invasion (LVSI) status of early-stage cervical cancer, and its added value to morphological MRI. A total of 72 patients with pathology-confirmed early-stage cervical cancer were enrolled, and classified into LVSI- positive (n=41) and LVSI- negative (n=31) groups. Together with morphological parameters including gross tumor volume (GTV) and maximum tumor diameter (MTD), the T1, T2, and proton density (PD) values of the tumors were also measured and compared between two groups. Binary logistic regression analysis was used to identify the independent variable associated with LVSI. Receiver operating characteristic curve analyses and DeLong tests were used to evaluate and compare the performances of significant parameters or their combination in predicting LVSI. LVSI- positive group showed significantly higher GTV (P=0.008) and MTD (P=0.019), and lower T1 (P<0.001) and PD values (P=0.041) than LVSI- negative group. However, no statistical significance was observed regarding the T2 values (P=0.331). Binary logistic regression indicated that T1 value (odds ratio [OR]=0.993; P=0.001) and MTD (OR=1.903, P=0.027) were independent variables associated with LVSI in early cervical cancer. Optimal performance could be achieved [area under ROC curve (AUC)=0.784; cut-off value=0.56; sensitivity=80.5%; specificity=71.0%] when combining T1 and MTD for predicting LVSI. Its performance was significantly better than that of MTD alone (AUC, 0.784 vs 0.662, P=0.035). syMRI might be a feasible approach, and it can provide added value to morphological MRI in predicting the LVSI status of early-stage cervical cancer.

Natural N/O/S co-doped defect-rich functional carbon materials for aqueous supercapacitors: Effect mechanism of N-containing functional groups on chemical activation

The efficient synthesis of porous carbons with a micro-mesoporous composite structure from low-cost, multi-source biomass was of significant importance for the fabrication of carbon-based supercapacitors. A novel method for the preparation of micro-mesoporous composite carbon materials by co-pyrolysis of multi-source biomass coupled with KOH activation was proposed in this study. The N, O and S co-doped micro-mesoporous composite carbon materials were synthesized using the bamboo and spiral algae as the precursors and KOH as the activator. Spiral algae, as the main source of heteroatoms, played multiple roles (pore forming agent, dopant and enhancer) in the co-pyrolysis process. The enhanced effect of heteroatom doping on KOH activation facilitated the formation of microporous structures. The KCA-500–2 exhibited a porous structure dominated by micropores, with a specific surface area (SSA) of 2421.85 m2/g. At 0.5 A/g, KCA-500–2 displayed an excellent capacitance of 460F/g and outstanding rate performance (73.5 %). The assembled aqueous symmetric supercapacitor (KCA//KCA) demonstrated a maximum energy density of 19.09 Wh/kg at a power density of 150 W/kg. In addition, KCA//KCA attained 97.96 % capacitance retention after 9,000 cycles. This work revealed the synergistic mechanism between N-containing functional groups and KOH activation, suggesting a theoretical guidance for the synthesis of high-performance supercapacitors.

A novel structural reliability analysis method combining the improved beluga whale optimization and the arctangent function‐based maximum entropy method

AbstractA novel structural reliability analysis method that combines the improved beluga whale optimization (IBWO) and the arctangent function‐based maximum entropy method (AMEM) is proposed in this paper. It aims to augment the accuracy of failure probability prediction in structural reliability analysis based on the traditional maximum entropy method (MEM). First, the arctangent function is introduced to avoid the effects of truncation error and numerical overflow in the traditional MEM. The arctangent function can nonlinearly transform the structural performance function defined on the infinite interval into a transformed performance function defined on the bounded interval. Subsequently, the undetermined Lagrange multipliers in the maximum entropy probability density function (MEPDF) of the transformed performance function are obtained using IBWO at a swifter convergence speed with heightened convergence accuracy. Finally, the MEPDF of the transformed performance function can be obtained by combining the IBWO and AMEM, and the structural failure probability can be predicted. The analysis of the metro bogie frame as an engineering example reveals that compared with the traditional MEM using the genetic algorithm to solve the Lagrange multipliers, the proposed method diminishes the relative error in failure probability prediction from 20.51% to only 0.09%. This method significantly enhances the prediction accuracy of failure probability.

Synthesis and electrochemical properties of microcanals Mg-S-Cu-S as an electrode material for energy storage applications

The synthesis of novel nanostructured electrode materials is the community demand to overcome energy crises. Herein, the nanostructured copper-sulfide, copper-cadmium-sulfide and copper-magnesium-sulfide (Cu-S, Cd-S-Cu-S and Mg-S-Cu-S) electrodes are synthesized by chemical vapor deposition technique. The changes in crystal growth and surface morphologies of Cu-S, Cd-S-Cu-S and Mg-S-Cu-S electrodes are associated with the formation of heterostructures and change in energy fluxes. The weight % of Ni, Cu, S; Ni, Cd, Cu, S; and Ni, Mg, Cu, S are found to be 8, 62, 30; 6, 16, 48, 30; 15, 14, 45, 26 are observed in Cu-S, Cd-S-Cu-S and Mg-S-Cu-S electrodes respectively. The Mg-S-Cu-S electrode showed superior specific capacitance of 4393 and 5657 F/g at 1 mV/s and 1.0 A/g respectively. The maximum energy density and power density of Mg-S-Cu-S electrode are found to be 141 Wh/kg and 2120 W/kg respectively. The cyclic retention after 3000 cycles of Cu-S, Cd-S-Cu-S and Mg-S-Cu-S electrodes are found to be 80.8, 87.5 and 96.2 % respectively. The simulation results show that the Cd-S-Cu-S followed more capacitive-controlled while Mg-S-Cu-S followed more diffusive controlled process. Result show that the Mg-S-Cu-S electrode is comparatively more suitable for portable energy storage devices.

In Situ, Nitrogen-Doped Porous Carbon Derived from Mixed Biomass as Ultra-High-Performance Supercapacitor.

How to address the destruction of the porous structure caused by elemental doping in biochar derived from biomass is still challenging. In this work, the in-situ nitrogen-doped porous carbons (ABPCs) were synthesized for supercapacitor electrode applications through pre-carbonization and activation processes using nitrogen-rich pigskin and broccoli. Detailed characterization of ABPCs revealed that the best simple ABPC-4 exhibited a super high specific surface area (3030.2-3147.0 m2 g-1) and plentiful nitrogen (1.35-2.38 wt%) and oxygen content (10.08-15.35 wt%), which provided more active sites and improved the conductivity and electrochemical activity of the material. Remarkably, ABPC-4 showed an outstanding specific capacitance of 473.03 F g-1 at 1 A g-1. After 10,000 cycles, its capacitance retention decreased by only 4.92% at a current density of 10 A g-1 in 6 M KOH. The assembled symmetric supercapacitor ABPC-4//ABPC-4 achieved a power density of 161.85 W kg-1 at the maximum energy density of 17.51 Wh kg-1 and maintained an energy density of 6.71 Wh kg-1 when the power density increased to 3221.13 W kg-1. This study provides a mixed doping approach to achieve multi-element doping, offering a promising way to apply supercapacitors using mixed biomass.

Phosphate ions functionalized metal-organic framework-derived cobalt oxide with improved redox reactivity for high-performance alkaline aqueous Zn-ion batteries

Alkaline aqueous Zn/Co3O4 batteries (AZCBs) have captured significant attention within the field of scalable grid energy storage due to their high output voltage (>1.8 V), superior safety profile, and low manufacturing cost. Nevertheless, the intrinsic Co3O4 material experiences limitations in terms of low electronic conductivity and insufficient active sites, consequently constraining its electrochemical performance in AZCBs. To address this challenge, this investigation focuses on the use of phosphate ions functionalized Co3O4 (referred to as PCO) material derived from cobalt-based metal-organic frameworks (Co-MOFs) as a cathode electrode in AZCBs. Both theory calculations and experimental verification illustrate that the functionalization with phosphate ion enhances the active sites for electrochemical redox reactions and increases the electrical conductivity of intrinsic Co3O4. Consequently, a pouch cell configuration of PCO-2||Zn with the optimized PCO-2 sample as cathode exhibits a high capacity of 162.0 mAh g−1, a maximum energy density of 265.7 Wh kg−1, a maximum power density of 16.39 kW kg−1. Furthermore, excellent long-term stability is observed, with the capacity retention rate reaching 92.3 % over 5000 cycles at a high current density of 5 A g−1. Additionally, the constructed fibrous flexible solid-state device also demonstrates notable long-term stability, with a capacity retention of 96 % after 2000 cycles under a high current density of 10 mA cm−2, and performs well under different deformation statuses. This successful approach may hold potential for the exploration of other cathode materials, such as Mn or V-based compounds, which may exhibit high performance in aqueous zinc-based batteries.

Oxygen-vacancy-enriched CuMn2O4@CoAl layered double hydroxide nickel foam serving as a sophisticated electrode material for asymmetric supercapacitors

CuMn2O4, the abundant spinel in the earth, is considered a promising electrode material in the fields of energy storage and conversion, its practical application are hindered by limitations such as the insufficient energy density and poor stability of the material. Here, CuMn2O4@CoAl layered double hydroxide nickel foam (CuMn2O4@CoAl LDH NF) with abundant oxygen vacancy was constructed applied as an electrode material by simple hydrothermal method and NaBH4 reduction. The electrochemical tests validate that CuMn2O4@CoAl LDH NF soaked in NaBH4 solution stirring for 0.5 h (donated as CuMn2O4@CoAl LDH NF-0.5) shows a remarkable specific capacitance of 1437.7 F · g−1 at the current density of 1.0 A · g−1. The capacitance retention remains 86.1 % even after enduring 5000 cycles at a higher current density of 8.0 A · g−1. Furthermore, the assembled CuMn2O4@CoAl LDH NF-0.5// activated carbon (AC) supercapacitor exhibits a capacitance of 167.5 F · g−1, achieving a maximum energy density of 52.44 Wh · kg−1 and a power density of 4029.5 W · kg−1 when operated at the current density of 1.0 A · g−1. The experimental results show that the prepared material has excellent conductivity, good chemical stability, remarkable specific capacitance, and stable cycle life as a supercapacitor electrode. All these results confirm that both the construction of CuMn2O4@CoAl LDH core-shell structure and the reduction of NaBH4 can introduce abundant oxygen vacancy defects in CuMn2O4@CoAl LDH NF, which can significantly improve the electrical conductivity and accelerate the redox kinetics.

Still waters and deep: Habitat characteristics, density and distribution of a lake-dwelling population of the freshwater pearl mussel Margaritifera margaritifera

The freshwater pearl mussel, Margaritifera margaritifera is widely considered to be confined to fast-flowing, near-pristine rivers, and is highly endangered throughout its Holartic range. Here we describe a large population of some 150–200,000 individuals of the freshwater pearl mussel living in an oligotrophic Irish lake.Employing underwater photographic techniques and snorkel diving, mussels were found in two separate locations in the lake. In the first location, 200 m from the shore, mussels were found at a maximum density of 43 m−2, in a largely random distribution in the sandy bed substrate of the lake, up to 9.5 m deep. In the second shoreline location, mussels were observed in dense aggregations up to 118 individuals m−2, in sandy pockets in between boulders and bedrock, in waters 1–2 m deep. In both locations, mussels were found associated with macrophytes – the charophyte Nitella sp. in the deeper location and the quillwort Isoetes lacustris in the shallower shoreline location. Juvenile mussels (>1.5 cm length) were observed lying exposed on the sediment surface in the shallow littoral location, indicating that recruitment occurs in this population, although no estimates of juvenile density were obtained.The discovery of a large population of lentic Margaritifera margaritifera has significant implications for the species’ conservation and indicates that there may be substantial lentic populations of the species elsewhere. The environmental envelope of the species is clearly much wider than thought and our discovery challenges assumptions about the fundamental feeding and reproductive biology of this endangered species.

The phosphorous-doped 2D nanosheet assembled 3D Mn2V2O7 microflowers on Ni foam as a binder-free electrode for high energy density asymmetric supercapacitor application

In recent times, transition-metal oxides have been recognized as highly promising candidates for supercapacitor applications. Nevertheless, their progress in diverse fields has been hindered by challenges such as poor electrical conductivity and a shortage of active reaction centers. Doping heteroatoms would overcome these drawbacks and enhance the supercapacitor properties in transition metal oxides. Herein, the phosphorous-doped 2D nanosheet assembled 3D Mn2V2O7 micro flowers were grown on the Nickel foam using the hydrothermal method and successively phosphatized in a tube furnace, which was utilized as a binder-free supercapacitor electrode. The synthesis process involved varying the concentration of phosphorus (P), resulting in the successful formation of uniform P-decorated Mn2V2O7 microflowers. The unique microflower structure and doping P into the Mn2V2O7 material enhance the electrochemical properties with a specific capacity of 850C g−1 (1545 F g−1) at 1 A g−1 in a three-electrode cell. Moreover, the assembled Mn2V2O7–600/NF//AC device delivers a specific capacity of 258C g−1 (211 F g−1) at 1 A g−1 with a remarkable rate of 47 % at a high current density of 20 Ag −1. The device achieved a maximum energy density of 43.2 Wh kg−1 at a power density of 604.7 W kg−1, and it maintained 91 % of initial capacity after 10,000 charge/discharge cycles at 20 A g−1. These results suggest that the P-doping 2D nanosheet assembled 3D Mn2V2O7 could be promising electrode materials for supercapacitor applications.

Dispersal of a dominant competitor can drive multispecies coexistence in biofilms

Despite competition for both space and nutrients, bacterial species often coexist within structured, surface-attached communities termed biofilms. While these communities play important, widespread roles in ecosystems and are agents of human infection, understanding how multiple bacterial species assemble to form these communities and what physical processes underpin the composition of multispecies biofilms remains an active area of research. Using a model three-species community composed of Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis, we show with cellular-scale resolution that biased dispersal of the dominant community member, P.aeruginosa, prevents competitive exclusion from occurring, leading to the coexistence of the three species. A P.aeruginosa bqsS deletion mutant no longer undergoes periodic mass dispersal, leading to the local competitive exclusion of E.coli. Introducing periodic, asymmetric dispersal behavior into minimal models, parameterized by only maximal growth rate and local density, supports the intuition that biased dispersal of an otherwise dominant competitor can permit coexistence generally. Colonization experiments show that WT P.aeruginosa is superior at colonizing new areas, in comparison to ΔbqsS P. aeruginosa, but at the cost of decreased local competitive ability against E.coli and E.faecalis. Overall, our experiments document how one species' modulation of a competition-dispersal-colonization trade-off can go on to influence the stability of multispecies coexistence in spatially structured ecosystems.

Effects of surfactants on the morphologies, structures, and electrochemical activities of WO3/Ag2O nanocomposites for supercapacitor electrodes

For energy storage, supercapacitors have been extensively developed. Among them, pseudocapacitors that use faradaic reactions of conductive polymers and transition metal oxides exhibit high electrochemical performance. In this study, WO3-based electrodes for high-performance pseudocapacitors were designed with Ag2O and various surfactants, with the aim to extend of the potential range and shape control of WO3 crystals. The WO3/Ag2O nanocomposites were prepared on a carbon cloth via chemical bath deposition with different types of surfactants: cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Pluronic F-127. Both Ag and the surfactants affected the morphology of the WO3 crystals; their crystal sizes were decreased, and the crystallinity was improved. The specific capacitance of the WO3/Ag2O nanocomposite was 621 F/g at 5 mV/s, whereas that of WO3 was 397 F/g. Furthermore, the specific capacitance of the nanocomposites increased with the use of surfactants: 960 F/g for WO3/Ag2O@Pluronic F-127, 641 F/g for WO3/Ag2O@CTAB, and 846 F/g for WO3/Ag2O@SDS at 5 mV/s. WO3/Ag2O@Pluronic F-127 had superior capacitance and exhibited a charge/discharge capacitance retention rate of 135 % after 2000 cycles at 5 A/g. The symmetric electrode configuration of WO3/Ag2O@Pluronic F-127 exhibited a maximum energy density of 85 W h kg−1 and a power density of 670 W kg−1. These results highlight the significant potential of the WO3/Ag2O@Pluronic F-127 nanocomposite electrode for future energy storage devices.

Modelling grain refinement under additive manufacturing solidification conditions using high performance cellular automata

Despite increasing applications of additively manufactured parts, they still suffer from anisotropic mechanical properties and can experience cracking due to coarse columnar grain structures induced by metal 3D printing. Microstructural control is promising avenue to overcome these challenges, but requires deeper understanding of factors controlling solidification, particularly regarding grain refinement. Addressing this gap, this study explores grain refinement in Al-Cu alloys with a process-microstructure linking cellular automata-finite difference (CAFD) approach supported by single-track laser surface remelting (LSR) experiments. To enhance the understanding of nucleation behaviour in alloys under additive manufacturing solidification conditions, this research analyses the influence of nucleation parameters on the post-LSR microstructures. Additionally, this study explores the computational dimensions of microstructure modelling, testing CA mesh sensitivity effects and benchmarking our CAFD models on two high-performance computing platforms. The CAFD model captures well the key microstructural features observed in LSR Al-Cu alloys with and without grain refiner addition. It is shown that the maximum nucleation density has a significant effect on the final microstructure, resulting in different proportions of coarse columnar grains resulting from epitaxial solidification, newly nucleated thin columnar grains, and equiaxed grains.