Ideal Range Research Articles

Defect-free ZnO nanorods with high angular distribution for enhanced excitonic emission

Low-temperature hydrothermal growth has emerged as a popular method for the fabrication of ZnO nanorods (NRs), increasing the functionality and utility of ZnO-based devices. In this work, we study the influence of growth time, temperature and seed layer on the dimensions and angular distribution of ZnO NRs. High-quality NRs with a crisscrossed 60° angular distribution have been grown with a 20–60 nm diameter and 600 nm length. We show that, within the ideal range of growth parameters, the growth time and temperature have no controllable influence on NR diameter and length, while the deposition method and size of the pre-growth deposited ZnO seeds affects diameter and NR angular alignment. We demonstrate advantages of using crisscross-aligned NRs over planar ZnO for the enhancement of ZnO excitonic emission by optical coupling with gold nanoparticles. These results can be readily adapted for applications that involve surface coating-mediated enhancement of both light emission and injection.Graphical abstract

Adaptive global energy optimal management strategy based on the Pontryagin’s minimum principle: An isolated microgrid example

Optimal control is a common control strategy to solve complex non-linear systems. Pontryagin’s minimum principle, as a typical optimal control theory, is widely used in energy management systems. Due to the randomness of new energy generation and the diversity of load power consumption, microgrid energy management system is a complex non-linear stochastic system. The efficient operation of microgrid energy management strategy largely depends on the real-time performance of the control algorithm. Pontryagin’s minimum principle is an offline control strategy, whose co-state variable λ depends on expert experience and needs to be manually adjusted according to different working conditions, so it is difficult to achieve real-time optimal control. First, the energy management system model of island-type microgrid is established in this paper. In order to improve the economy of power generation and prevent battery over-charge or over-discharge, the state of charge (SOC) change of battery pack is comprehensively considered, and the fuel cost and pollutant treatment cost are taken as the objective function. Second, an adaptive Pontryagin’s minimum principle energy management strategy is proposed. By introducing the penalty mechanism and adjusting the parameters adaptively, the problem that the open-loop control of Pontryagin’s minimum principle needs to adjust the co-state variables in real time is solved. Comparative experiments show that compared with Pontryagin’s minimum principle and particle swarm optimization, adaptive Pontryagin’s minimum principle can not only limit battery SOC within the ideal range but also effectively reduce the daily operation cost of microgrid. Experimental results verify the effectiveness of the proposed algorithm.

From Waste Biomass to Hard Carbon Anodes: Predicting the Relationship between Biomass Processing Parameters and Performance of Hard Carbons in Sodium-Ion Batteries

Sodium-ion batteries (SIBs) serve as the most promising next-generation commercial batteries besides lithium-ion batteries (LIBs). Hard carbon (HC) from renewable biomass resources is the most commonly used anode material in SIBs. In this contribution, we present a review of the latest progress in the conversion of waste biomass to HC materials, and highlight their application in SIBs. Specifically, the following topics are discussed in the review: (1) the mechanism of sodium-ion storage in HC, (2) the HC precursor’s sources, (3) the processing methods and conditions of the HCs production, (4) the impact of the biomass types and carbonization temperature on the carbon structure, and (5) the effect of various carbon structures on electrochemical performance. Data from various publications have been analyzed to uncover the relationship between the processing conditions of biomass and the resulting structure of the final HC product, as well as its electrochemical performance. Our results indicate the existence of an ideal temperature range (around 1200 to 1400 °C) that enhances the formation of graphitic domains in the final HC anode and reduces the formation of open pores from the biomass precursor. This results in HC anodes with high storage capacity (>300 mAh/g) and high initial coulombic efficiency (ICE) (>80%).

Willingness to pay for reduced travel time: Case study of Mumbai - Ahmedabad High Speed Railway

India is constructing its first High Speed Railway (HSR) corridor between Mumbai and Ahmedabad, which is expected to reduce inter-city travel times significantly. However, the affordability of these reductions in travel time is still questionable for a developing country like India. This study analyses the existing conventional train travellers’ Willingness to Pay (WTP) for reduced travel time due to HSR. A questionnaire-based combined RP-SP survey was conducted in Mumbai to capture respondents’ travel details, socioeconomic status and Stated Preference choices. The modified open-ended contingent valuation method and binary logistic regression modelling methods were used for data collection and modelling, respectively. Differential Utility Weighted Mean WTP was calculated for multiple socioeconomic cohorts. It was found that travellers are willing to pay an average INR 300 (as on March 2020) over and above their current travel cost for every hour of travel time saving. The ideal fare range that travellers are willing to pay is between INR 3.25/km to INR 5.25/km. Low-income travellers, occasional travellers, those travelling in a group, and those on social trips had the lowest WTP values in their cohorts. On the contrary, regular business travellers with high incomes had the highest WTP. Analysis showed that the WTP of individuals decreases with the increasing no. of co-passengers and with the increasing comfort of competing modes. The future HSR in India needs a group ticket discount of 10% and an average 25% subsidy on monthly passes to make HSR more attractive for commuters and those travelling with families. This research would help draft the HSR operational policies for subsidies, stronger inter-modal competition, loss minimisation for conventional trains and ridership forecasts.

Abstract P396: A Culturally Tailored Mobile Health Lifestyle Intervention Improves Cardiovascular Health Among African Americans With Preexisting Risk Factors

Background: African-American (AA) adults have a higher prevalence of cardiovascular (CV) risk factors, leading to higher CV disease mortality than White adults. Prior findings of our mobile health (mHealth) lifestyle intervention (FAITH! App) demonstrated efficacy in promoting ideal cardiovascular health (CVH) in AAs. Hypothesis: We hypothesized that the intervention group with preexisting CV risk factors would have a greater increase in LS7 scores than the control group with the same risk factors following use of the FAITH! App. Methods: A cluster randomized controlled trial was conducted among AAs from 16 churches in Minnesota. The intervention included culturally relevant, LS7-focused education modules, diet/physical activity self-monitoring and a group sharing board. A subgroup of participants with ≥1 diagnosis of overweight/obesity, hyperlipidemia, hypertension (HTN) or diabetes was examined. The primary outcome was change in LS7 score—a measure of CVH ranging from poor to ideal (range 0-14 points)—at 6 months post-intervention. Results: Forty-nine participants (75.5% female) were included in the intervention (n=20; mean age [SD]: 58.8 [9.5]) or control (n=29, mean age [SD]: 52.5 [10.7]) groups (Table 1). There was no significant difference in the CV risk factor prevalence between the two groups. There was a greater increase in LS7 score in the intervention vs. control group across all CV risk factors, with significant differences among those with overweight/obesity (1.77, p<.0001) and with 2+ or 3+ CV risk factors (1.00, p=.03; 1.09, p=.04). Compared to the control group, the increase in the percentage of participants with ideal LS7 scores in the intervention group was higher among those with overweight/obesity, HTN, diabetes and 3+ CV risk factors. Conclusions: Our culturally tailored mHealth lifestyle intervention was associated with notable increases in LS7 scores among AAs with preexisting CV risk factors, suggesting its efficacy in improving CVH among this population.

Strategies for Optimizing the Morphology of CsSnI3 Perovskite Solar Cells

Over the past decade, organic–inorganic hybrid perovskite solar cells (PVSCs) have shown unprecedented growth in power conversion efficiency (PCE) from 3.8% to 25.7%. However, intrinsic thermal instability and lead toxicity are obstacles limiting its large–scale commercialization. Thus, all-inorganic CsSnI3 perovskite has drawn remarkable interest owing to its nontoxicity, excellent thermal stability, low-cost fabrication, and spectacular photoelectric characteristics, including ideal bandgap range, long carrier lifetime, and large absorption coefficient. Many studies have shown that the device performances are closely related to the morphology and crystallinity of perovskite films. In this review, the physical properties of CsSnI3 perovskite are summarized. Furthermore, this review primarily narrates the recent progress in optimizing the morphology by various strategies such as additive engineering, composition regulation, and deposition techniques, emphasizing their effects on grain sizes, film uniformity, grain boundary, and defect passivation.

Flexible stretchable SEBS/n-alkane phase change composite films for highly efficient thermal management and infrared stealth applications

Phase change materials (PCMs) can alleviate concerns about energy to a certain extent by reversibly storing a plenty of renewable and sustainable thermal energy. However, they do not have any flexibility due to their liquid leakage and solid rigidity, making them unsuitable for further practical wearable applications. Herein, a series of SEBS/n-alkane PCM composite films (PCMFs) were fabricated. SEBS is mainly used as the supporting substrate to prevent the leakage of liquid n-alkanes and endue the PCMFs with excellent mechanical properties. Where, the tensile strain and tensile strength of SEBS/n-HD-50% PCMF separately are 780% and 9.96 MPa, representing excellent stretchability and deformability, tailorability, and foldability. Particularly, the onset melting and crystallization temperatures (Tmo, Tco) of SEBS/n-ES-50% and SEBS/n-DS-50% PCMFs individually are 28.1 °C and 28.4 °C, 33.8 °C and 35.7 °C, which match the comfort zone for human skin and the ideal thermo-response temperature range of smart windows, and a range of experiments have verified their feasibility in the fields of thermal management, smart windows and infrared stealth. This study well solves the problems of liquid leakage and solid rigidity of PCMs themselves, endows them with excellent comprehensive performance, and greatly expanding the practical applications of PCMs.

Effect of stocking density and water depth on the growth and production of red seaweed, Gracilaria tenuistipitata in the Kuakata coast of Bangladesh

Seaweed aquaculture, the quickly growing global food production segment, provides plenty of options for mitigating and adapting to developed-world conditions. In Bangladesh, the rise of seaweed cultivation gives hope for increasing incomes in fishing villages. The effect of stocking density (1, 2, 3, and 4 Kg/m2) and water depth (surface, 0.5 m, and 1.0 m) on cultivating red seaweed, Gracilaria tenuistipitata, using the square raft (1 m × 1 m) method was evaluated on the Kuakata coast of Bangladesh from December 2021 to March 2022. The raft was made of bamboo, rope, and plastic containers. Hydrological parameters and other growth indicators were monitored fortnightly. Temperature (27.3–29.5 °C), transparency (53.8–57.3 cm), salinity (18.6–21.4), pH (7.4–7.9), and dissolved oxygen (5.7–6.2 mg/L) were all found to be adequate for seaweed farming, however, salinity was somewhat lower than the ideal range. The initial stocking density of 2 Kg/m2 with a culture period of 60 days was found to be the most suitable for G. tenuistipitata than other stocking densities in terms of daily growth rate (DGR). The maximum biomass yield (13.52 ± 2.04 Kg/m2) was observed at a stocking density of 4 Kg/m2, but no significant difference (p < 0.05) was detected among stocking densities of 2, 3, and 4 Kg/m2. Furthermore, as compared to the surface and 1.0 m water depth, the daily growth rate was significantly higher at a depth of 0.5 m. However, at a water depth of 0.5 m, there was a rising trend in biomass yield, after which it declined significantly (p < 0.05). Based on the findings, the current study suggests that cultivating G. tenuistipitata at a stocking density of 2 Kg/m2 at a water depth of 0.5 m can produce greater DGR and biomass production, which might provide monetary benefits to small farmers in Bangladesh's Kuakata coast, Bay of Bengal.

Nanosized La0.4Gd0.2Sr0.4MnO3 manganites: From magnetic refrigeration to hyperthermia method

The structural, magnetic, and magnetocaloric characteristics of the nanosized La0.4Gd0.2Sr0.4MnO3 manganites were discussed based on the influence of heating temperature (700 and 1000 °C). We investigated it, further, to present the strong link between magnetic refrigeration and hyperthermia technique. Both samples are nanosized according to the study of the scanning electron microscopy and the X-ray diffraction patterns (Scherrer and Williamson-Hall plots). Analyzing the thermal evolution of the magnetizations proves that various magnetic states are present in both samples, superparamagnetism, spin-glass, ferromagnetism, and paramagnetism. We demonstrated that the Curie temperature is between 318 and 331 K, which is the ideal range for the hyperthermia approach. The relative cooling power at 6 T is around 404.085 J/Kg for LGSM_1000; thus, this sample is an excellent candidate for magnetic cooling. It is a great achievement result that the rate of evolution from LGSM_700 to LGSM_1000 is 3213.26 %.

Identification of Yield-Limiting Nutrients for Sorghum (Sorghum bicolor (L.) Moench) Yield, Nutrient Uptake and Use Efficiency on Vertisols of Raya Kobo District, Northeastern Ethiopia

Agricultural productivity was negatively impacted by low soil fertility and uneven fertilizer application during crop cultivation in Ethiopia. Because of this, important crops frequently respond to fertilizer applications significantly below their achievable and potential yields. This study was carried out to determine the most sorghum yield-limiting nutrients in the Raya Kobo area of the Amhara Region in the 2020/21 crop season. Sorghum variety Girana-One was used as the test crop. Control, NPS, PSBZn, NPBZn, NSBZn, NPSB, NPSZn, NPSBZn, recommended NP, and NPSKBZn were treatments. Three replications of the experiment were used in a randomized complete block design. Before treatment application, a composite soil sample was collected at a depth of 0–20 cm to determine the soil’s physicochemical properties. To evaluate N and P uptakes, samples of sorghum stalk and grain were collected. SAS software was used to analyze the data. Results showed that, NPKSZnB produced a considerably greater grain yield (4620 kg·ha−1), whereas the control and N omitted plots produced the lowest grain yields (2759 kg·ha−1) and 2805 kg·ha−1, respectively. Nitrogen fertilizer missing plots showed a statistically significant yield drop compared to the other plots, and there was no statistically significant yield difference between the prescribed NP plots and the potassium, sulfur, boron, or zinc omitted plots. The plots treated with NPKSZnB had the highest agronomic efficiency for N (19.7 kg grain kg−1·N) and P (10.6 kg grain kg−1 P2O5). Therefore, research and development should therefore concentrate on nitrogen to achieve the best sorghum yield for the study location. Phosphorus might also be used to keep the fertility level within the ideal range.

Potential application of two-dimensional PC6 monolayer as an anode material in alkali metal-ion (Li, Na, K) batteries

The development of two-dimensional (2D) materials in anode has been believed as a significant research direction to promote the innovation of alkali metal-ion batteries. Lately, PC6 monolayer, a neoteric material, has stimulated people's research enthusiasm owing to its outstanding thermodynamic and electrical natures. In this paper, by employing the first-principles calculation method based on density function theory, the feasibility of PC6 monolayer acting as an anode in alkali metal-ion batteries has been systematically evaluated. The simulation results indicate that, when acting as anode material, the PC6 monolayer can not only provide effective adsorption interaction for metal ions which is beneficial for inhibiting the formation of clusters, but also can furnish satisfactory storage capacity (1496.23 mA·h·g−1 for Li, 1301.07 mA·h·g−1 for Na, and 780.63 mA·h·g−1 for K). Meanwhile, PC6 monolayer can supply appropriate average open-circuit voltages (0.48/0.40/0.64 V for Li/Na/K), which are all within the ideal voltage range of anode material. Importantly, the appraised diffusion behaviors further reflect the isotropic property and wonderful migration performance (0.42/0.46/0.29 eV for Li/Na/K) of PC6 monolayer for metal ions. Remarkedly, the ab initio molecular dynamics simulations results illustrate that these saturated adsorption systems have excellent deformation resistance at a high temperature of 400 K. These exciting performances endow the PC6 monolayer with promising application prospects as an anode in alkali metal-ion batteries.

Finite element method based design and performance analysis of universal motor for agro applications

A universal motor is one that is capable of operating on either AC or DC power supply. The commutator is a component of the motor that has a significant impact on how efficiently the motor operates. It is essential to conduct an analysis of the pole structure of the universal motor in order to investigate the many aspects. The parametric study of a universal motor with a rating of 1 horsepower and 15,000 revolutions per minute that was designed with various combinations of brush angle and pole embrace factor for use in agricultural applications. The purpose of this study is to improve the effectiveness of the motor while preserving the ideal tolerance range for the model's other parameters as much as possible. The approach now allows for a greater degree of personalization for each distinct combination of factors. With the assistance of the finite element method (FEM), the transient solution is carried out so that the performance of the motor can be evaluated more accurately. The model that has been designed provides major design improvements, one of which is an improved average torque.

Expediting cryo-EM sample preparation using design of experiments.

Determining cryo-EM grid freezing parameters to attain optimal particle distribution and ice thickness for data collection is a highly sample-specific process which frequently requires several iterative rounds of freezing and screening grids. Researchers relying on national cryo-EM centers and similar facilities for screening services can be subject to lengthy wait times for each screening session, which may delay research considerably if many rounds are needed. This provides a strong motivation for a more strategic and efficient approach to grid optimization. Here, we present a method of using Design of Experiments to more efficiently optimize the parameter space to produce data-collection-ready grids in as little as two rounds of freezing and screening. We employ a fractional factorial design to probe a wide range of parameters including blotting conditions, sample characteristics, and grid characteristics through a relatively small set of test conditions. Quantitative screening results based on ice thickness and particle distribution are used to generate a least squares regression model, which provides a set of optimized freezing conditions. We tested this approach with apoferritin on both the Vitrojet and Leica GP2, and with glutamate dehydrogenase on the Vitrobot. For all three attempts, grids were frozen with the optimized conditions given by the model. Optimized grids in each case had ice thickness within an ideal range for data collection and a near-monolayer of particles, with enough imageable area to support multiple days of data collection. Resulting grids were of consistent quality when the procedure was performed by different researchers on different vitrification instruments and on different days. Based on the quality of the optimized grids produced in these experiments, we conclude that this is a robust and reliable method for expediting and improving the overall success of the cryo-EM grid optimization process.

Time-Varying Pattern and Prediction Model for Geopolymer Mortar Performance under Seawater Immersion.

In this study, immersion experiments were conducted on the geopolymer mortar (GPM) by using artificial seawater, and the effects of alkali equivalent (AE) and waterglass modulus (WGM) on the resistance of geopolymer mortar (GPM) to seawater immersion were analyzed. The test subjected 300 specimens to 270 days of artificial seawater immersion and periodic performance tests. Alkali equivalent (AE) (3-15%) and waterglass modulus (WGM) (1.0-1.8) were employed as influencing factors, and the mass loss and uniaxial compressive strength (UCS) were used as the performance evaluation indexes, combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze the time-varying pattern of geopolymer mortar (GPM) performance with seawater immersion. The findings demonstrated a general trend of initially growing and then declining in the uniaxial compression strength (UCS) of geopolymer mortar (GPM) under seawater immersion. The resistance of geopolymer mortar (GPM) to seawater immersion decreased with both higher or lower alkali equivalent (AE), and the ideal range of alkali equivalent (AE) was 9-12%. The diffusion layer of the bilayer structure of the waterglass particle became thinner with an increase in waterglass modulus (WGM), which ultimately led to the reduction in the resistance of the geopolymer structure to seawater immersion. Additionally, a support vector regression (SVR) model was developed based on the experimental data to predict the uniaxial compression strength (UCS) of GPM under seawater immersion. The model performed better and was able to achieve accurate prediction within 1-2 months, and provided an accurate approach to predicting the strength of geopolymer materials in a practical offshore construction project.

A Review of Gallic Acid-Mediated Fenton Processes for Degrading Emerging Pollutants and Dyes.

Diverse reducing mediators have often been used to increase the degradation of emerging pollutants (EPs) and dyes through the Fenton reaction (Fe2+ + H2O2 → Fe3+ + HO● + HO-). Adding reductants can minimize the accumulation of Fe3+ in a solution, leading to accelerated Fe2+ regeneration and the enhanced generation of reactive oxygen species, such as the HO● radical. The present study consisted in reviewing the effects of gallic acid (GA), a plant-extracted reductant, on the Fenton-based oxidation of several EPs and dyes. It was verified that the pro-oxidant effect of GA was not only reported for soluble iron salts as a catalyst (homogeneous Fenton), but also iron-containing solid materials (heterogeneous Fenton). The most common molar proportion verified in the studies was catalyst:oxidant:GA equal to 1:10-20:1. This shows that the required amount of both catalyst and GA is quite low in comparison with the oxidant, which is generally H2O2. Interestingly, GA has proven to be an effective mediator at pH values well above the ideal range of 2.5-3.0 for Fenton processes. This allows treatments to be carried out at the natural pH of the wastewater. The use of plant extracts or wood barks containing GA and other reductants is suggested to make GA-mediated Fenton processes easier to apply for treating real wastewater.

One-step fabrication of hydrophobic metal-organic framework@covalent organic framework hybrid as sorbent for high-performance solid-phase extraction of flavonoids

Metal-organic framework (MOF) and covalent organic framework (COF) exhibit excellent extraction performance in sample pretreatment, but their wider application is hindered by some inherent drawbacks. Herein, we successfully synthesized a novel MOF@COF hybrid material with large specific surface area, good chemical stability and reusability, which is suitable as a solid phase extraction (SPE) sorbent for the efficient extraction of flavonoids. Importantly, due to the synergistic effect, the obtained MOF@COF hybrid material showing a higher extraction efficiency than individual MOF and COF. This is mainly due to the obtained MOF@COF hybrid material combines the high specific surface area of MOF and multiple interactions (hydrophobic interaction, hydrogen bonding and π-π stacking interaction) with flavonoids conferred by the COF structure. Then, a sensitive analytical method for flavonoids with ideal linear range (1–500 ng mL−1), low detection limit (0.15–0.41 ng mL−1) and good repeatability (2.64–6.20%) was developed under optimized conditions. In addition, the MOF@COF hybrid sorbent has better selectivity for hydrophobic targets containing multiple hydrogen bond acceptors/donors. Finally, the established method was applied to the determination of flavonoids in different food samples, and satisfactory recoveries (81.4–102.1%) were obtained, which initially confirmed its applicability.

Docking-aided rational tailoring of a fluorescence- and affinity-enhancing aptamer for a label-free ratiometric malachite green point-of-care aptasensor

Although nucleic acid aptasensors are increasingly applied in the detection of environmentally hazardous biomolecules, several formidable challenges remain with this technique because of their vulnerability, high cost and suboptimal sensitivity. Here, a docking-aided rational tailoring (DART) strategy was established at three levels and in two dimensions for the refinement of malachite green (MG) DNA aptamers. Guided by in silico molecular docking, coarse and fine tailoring were conducted at three levels each, to significantly enhance fluorescence activation intensity and binding affinity in two dimensions. Empowered by the results of the rational tailoring, a mechanistic view of the MG DNA aptamer-target interaction was thoroughly analyzed via four types of interactions. To meet the demand for point-of-care testing (POCT), a label-free and ratiometric fluorescent aptasensor was developed leveraging the tailored MG aptamer, based on the binding site competition-equilibrium effect via the introduction of a reference dye. This sensitive, specific, low-cost and rapid aptasensor subsequently demonstrated outstanding detection performance, achieving an ideal signal response range of 5 nmol·L−1 - 6 μmol·L−1 and a low limit of detection (LOD) of 1.49 nmol·L−1. The DART strategy and systematic exploration of the MG DNA luminescent aptamers herein will provide a valuable reference in the field of aptamer tailoring, biosensing and bioimaging. The proposed label-free ratiometric aptasensor also provides a highly generalizable strategy for hazardous biomolecular detection.

Development of inferiority-compensation scale among high school students

An increasing number of high school students are inflicted by different degrees of mental disorders in learning, such as moodiness, learning difficulties, test anxiety, difficulty coping with frustration, etc., which are one of the factors leading to the inferiority of students. In the present study, the initial scale of inferiority compensation for high school students was developed through literature searching, expert evaluation, interviews, and an open scale. 1187 high school students were tested in different periods, after deleting an invalid 83 scales, including 461 copies of valid scale of exploratory factor analysis in the first stage and 643 copies of valid scale of confirmatory factor analysis in the second stage. The results showed that the inferiority compensation scale for high school students consisted of two sub-scale: self-compensation and others-compensation, ach two were composed of five dimensions including academic performance, physical fitness, social communication, appearance, and self-esteem. Confirmatory factor analysis showed that the total scale and the two sub-scale all had good structural validity (RMSEA≤0.08; CFI&IFI ≥ 0.9), and the combined reliability and values (such as the correlation coefficient of each dimension) of the two sub-scale were within the ideal range. With good reliability and validity (Cronbacα&KMO ≥ 0.90), and meeting the requirements of psychometrics, the scale can be used in the relevant research and practice of inferiority compensation for high school students.

Star formation histories of UV-luminous galaxies at z ≃ 6.8: implications for stellar mass assembly at early cosmic times

ABSTRACT The variety of star formation histories (SFHs) of z ≳ 6 galaxies provides important insights into early star formation, but has been difficult to systematically quantify. Some observations suggest that many z ∼ 6–9 galaxies are dominated by ≳200 Myr stellar populations, implying significant star formation at z ≳ 9, while others find that most reionization era galaxies are ≲10 Myr, consistent with little z ≳ 9 star formation. Here, we quantify the distribution of ages of UV-bright ($-22.5\lesssim M_{\rm \small UV}\lesssim -21$) galaxies colour-selected to lie at z ≃ 6.6–6.9, an ideal redshift range to systematically study the SFHs of reionization era galaxies with ground-based observatories and Spitzer. We infer galaxy properties with two SED modelling codes and compare results, finding that stellar masses are largely insensitive to the model, but the inferred ages can vary by an order of magnitude. We infer a distribution of ages assuming a simple, parametric SFH model, finding a median age of ∼30–70 Myr depending on SED model. We quantify the fractions of ≤10 and ≥250 Myr galaxies, finding that these systems comprise ∼15–30 per cent and ∼20–25 per cent of the population, respectively. With a flexible SFH model, the shapes of the SFHs are consistent with those implied by the simple model (e.g. young galaxies have rapidly rising SFHs). However, stellar masses can differ significantly, with those of young systems sometimes being more than an order of magnitude larger with the flexible SFH. We quantify the implications of these results for z ≳ 9 stellar mass assembly and discuss improvements expected from JWST.

A Numerical Study of the Suitability of Phase-Change Materials for Battery Thermal Management in Flight Applications

Battery pack specific energy, which can be enhanced by minimising the mass of the battery thermal management system (BTMS), is a limit on electric fixed-wing flight applications. In this paper, the use of phase-change materials (PCMs) for BTMSs is numerically explored in the 3D domain, including an equivalent circuit battery model. A parametric study of PCM properties for effective thermal management is conducted for a typical one-hour flight. PCMs maintain an ideal operating temperature (288.15 K–308.15 K) throughout the entire battery pack. The PCM absorbs heat generated during takeoff, which is subsequently used to maintain cell temperature during the cruise phase of flight. In the control case (no BTMS), battery pack temperatures fall below the ideal operating range. We conduct a parametric study highlighting the insignificance of PCM thermal conductivity on BTMS performance, with negligible enhancement observed across the tested window (0.1–10 W m−1 K−1). However, the PCM’s latent heat of fusion is critical. Developers of PCMs for battery-powered flight must focus on enhanced latent heat of fusion, regardless of the adverse effect on thermal conductivity. In long-haul flight, an elongated cruise phase and higher altitude exasperate this problem. The unique characteristics of PCM offer a passive low-mass solution that merits further investigation for flight applications.