Phosphorus-doped three-dimensional hierarchical porous carbons (P-3DHPCs) have been synthesized by direct pyrolysis of mixture containing glucose, manganese nitrate and sodium hypophosphite without ...any hard templates. Glucose and sodium hypophosphite are used as carbon and phosphorus source in the facile template-free strategy, respectively. The P-3DHPCs not only possess favorable hierarchical pore structure which is beneficial to ion adsorption and transportation, but also acquire effective heteroatoms doping, further improving the capacitive performance. More importantly, the amount of sodium hypophosphite plays a critical role in textural properties and phosphorus content of P-3DHPCs. The results demonstrate that P-3DHPC-0.2 shows the best electrochemical performance compared to the other samples. High specific capacitance (367 F g−1 at 0.3 A g−1) is obtained in 6 M KOH, and the capacitance still maintains 319 F g−1 when tested at 20 A g−1 (ca.88% capacitance retention). Moreover, the P-3DHPC-0.2 also possesses good cycling stability with only a loss of 3.5% after 10000 cycles at 3 A g−1. The facile preparation method and good electrochemical performance render P-3DHPCs to be a promising candidate for supercapacitor application.
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Clean and sustainable electrochemical energy storage has attracted extensive attention. It remains a great challenge to achieve next-generation rechargeable battery systems with high energy density, ...good rate capability, excellent cycling stability, efficient active material utilization, and high coulombic efficiency. Many catalysts have been explored to promote electrochemical reactions during the charge and discharge process. Among reported catalysts, single-atom catalysts (SACs) have attracted extensive attention due to their maximum atom utilization efficiency, homogenous active centres, and unique reaction mechanisms. In this perspective, we summarize the recent advances of the synthesis methods for SACs and highlight the recent progress of SACs for a new generation of rechargeable batteries, including lithium/sodium metal batteries, lithium/sodium-sulfur batteries, lithium-oxygen batteries, and zinc-air batteries. The challenges and perspectives for the future development of SACs are discussed to shed light on the future research of SACs for boosting the performances of rechargeable batteries.
Single-atom catalysts are reviewed, aiming to achieve optimized properties to boost electrochemical performances of high-energy batteries.
This study aims to investigate how milling parameters and tool geometric parameters affect the milling mechanism of aluminum alloy 7050-T7451. A two-dimensional high-speed milling model of aluminum ...alloy 7050-T7451 is established based on Advantedge; the effects of milling parameters (milling speed, cutting depth) and tool geometric parameters (tool rake angle, tool blunt radius) on milling force and milling temperature are identified through single factor experiment. The results show that as milling speed increases, Fx first reduces and then increases, whereas Fy first increases and then reduces; milling temperature first increases and then gradually reduces after a given speed is reached, but the overall change is modest. Milling depth is positively correlated to milling force and milling temperature. As tool rake angle increases, both milling force and milling temperature reduce. Tool blunt radius is positively correlated to Fx and Fy and makes no difference to milling temperature.
•The effects of different tool geometry parameters on machinability were studied.•Finite element models of 7050-T7451 aluminum alloy with different milling parameters were established.•The forming mechanism of milling has been proved.
Exploiting high-efficiency catalysts toward hydrogen evolution reaction (HER) is a significant assignment nowadays. We find a quick and straightforward means to produce large-scale g-C3N4, which does ...not use template and easily obtains uniform nanostructures. And, we fabricate one-step preparation of a non-noble-metal catalyst, consisting of carbon material and transition metal only, by coupling graphitic carbon nitride (g-C3N4) with Ni. The results show that Ni/C3N4 composite catalyst possesses coral-like structure and its unique morphology is in favor of electrochemical activity for HER. Simultaneously, the Ni/C3N4 composite catalyst presented prominent activity on HER with a high exchange current density of 1.91 × 10–4 A cm–2, a low Tafel slope of 128 mV dec–1 and small overpotentials of 356 and 222 mV to reach current densities of 100 and 10 mA cm–2, which are superior to those of the state-of-the-art HER-active Ni-based compositions, as well as majority other metal-free catalysts, and even rivaled the electrocatalytic property of commercial Pt/C catalyst.
The angle of throwing and the speed of throwing are very important technical indicators in the javelin throwing training process. It is helpful to improve the effect of training according to the ...feedback information in real time for each training session. In view of this situation, based on the embedded technique, we designed and produced the javelin-throwing posture measuring system. A new intelligent training javelin with an embedded moving posture measurement system was manufactured through further mechanical design and processing. This intelligent javelin can realize the real-time inspection and transmission of key javelin-throwing parameters and quantitatively describe the regular moving pattern of a javelin thrower. Coaches and athletes may analyze the training results according to the parameters they get from our system, which realize quantification and modification of javelin training and provide technical support to the improvement of the athletic level of javelin throw.
Abstract
Background
Currently, the direct method is the main approach for establishment of reference interval (RI). However, only a handful of studies have described the effects of sample size on ...establishment of RI and estimation of sample size. We describe a novel approach for estimation of the sample size when establishing RIs using the transformed parametric and non-parametric methods.
Methods
A total of 3,697 healthy participants were enrolled in this study. We adopted a two-layer nested loop sample size estimation method to determine the effects of sample size on RI, using thyroid-related hormone as an example. The sample size was selected as the calculation result when the width of the confidence interval (CI) of the upper and lower limit of the RI were both stably < 0.2 times the width of RI. Then, we calculated the sample size for establishing RIs via transformed parametric and non-parametric methods for thyroid-related hormones.
Results
Sample sizes for thyroid stimulating hormone (TSH), as required by parametric and non-parametric methods to establish RIs were 239 and 850, respectively. Sample sizes required by the transformed parametric method for free triiodothyronine (FT3), free thyroxine (FT4), total triiodothyronine (TT3) and total thyroxine (TT4) were all less than 120, while those required by the non-parametric method were more than 120.
Conclusion
We describe a novel approach for estimating sample sizes for establishment of RI. A corresponding open-source code has been developed and is available for applications. The established method is suitable for most analytes, with evidence based on thyroid-related hormones indicating that different sample sizes are required to establish RIs using different methods for analytes with different variations.
Developing energy production, storage, and conversion technologies based on sustainable or renewable energy is essential to address the energy and environmental crisis. Electrochemical water ...splitting is one of the most promising approaches to realize the production of green hydrogen. The design of catalytic materials with low cost, high activity, and long‐term stability and the exploration of specific reaction mechanisms are the key focus for the involved electrochemical hydrogen evolution reaction (HER). Recently, substantial efforts have been devoted to the rational design and synthesis of non‐noble metallic heterostructures with fascinating synergistic effects among different components. These heterostructured materials demonstrate comprehensive properties exceeding the estimations by the rule of mixtures and display high activity and long‐term stability in industrial conditions for HER. Herein, the reaction mechanism and key parameters for improving catalytic performance in the HER process are discussed in detail. The latest advances in heterostructures based on synthetic methods and electrocatalytic characteristics from experimental and computational perspectives are summarized according to the role of various components. Herein, insights are provided in this review into an in‐depth understanding of the heterostructures as HER electrocatalysts, and the opportunities and challenges to scale up future‐oriented developments are highlighted.
The lack of efficient and non-precious metal catalysts poses a challenge for electrochemical water splitting in hydrogen and oxygen evolution reactions. Here, we report on the preparation of growing ...Ni(OH)2 nanosheets in situ on a Ni and graphene hybrid using supergravity electrodeposition and the hydrothermal method. The obtained catalyst displays outstanding performance with small overpotentials of 161.7 and 41 mV to acquire current densities of 100 and 10 mA cm−2 on hydrogen evolution reaction, overpotentials of 407 and 331 mV to afford 100 and 50 mA cm−2 on oxygen evolution reaction, and 10 mA·cm−2 at a cell voltage of 1.43 V for water splitting in 1 M KOH. The electrochemical activity of the catalyst is higher than most of the earth-abundant materials reported to date, which is mainly due to its special hierarchical structure, large surface area, and good electrical conductivity. This study provides new tactics for enhancing the catalytic performance of water electrolysis.
Compound epidermal growth factor receptor (EGFR) mutations are less responsive to tyrosine kinase inhibitors (TKIs) than single EGFR mutations in non-small cell lung cancer (NSCLC). However, the ...detailed clinical characteristics and prognosis of various compound EGFR mutations remain to be elucidated.
We retrospectively studied the next-generation sequencing (NGS) data of treatment-naïve tumors from 1025 NSCLC patients with compound EGFR mutations, which were sub-categorized into different combinations of common mutations (19-Del and EGFR exon 21 p.L858R), rare mutations, and variants of uncertain significance (VUSs). Prognosis and drug resistance to first-line TKIs were analyzed in 174 and 95 patients, respectively.
Compound EGFR mutations were enriched with EGFR exon 21 p.L858R and rare mutations, but not 19-Del (P < 0.001). The common + rare and rare + rare subtypes had fewer concurrent mutations in the PI3K pathway (P = 0.032), while the rare + rare and common + VUSs subtypes showed increased association with smoking- and temozolomide-related mutational signatures, respectively (P < 0.001). The rare mutation-dominant subtypes (rare + VUSs and rare + rare) had the worst clinical outcomes to first-line TKIs (P < 0.001), which was further confirmed using an external cohort (P = 0.0066). VUSs in the rare + VUSs subtype selectively reside in the EGFR kinase domain (P < 0.001), implying these tumors might select additional mutations to disrupt the regulation/function of the kinase domain.
Different subtypes of compound EGFR mutations displayed distinct clinical features and genetic architectures, and rare mutation-dominant compound EGFR mutations were associated with enriched kinase domain-resided VUSs and poor clinical outcomes. Our findings help better understand the oncogenesis of compound EGFR mutations and forecast prognostic outcomes of personalized treatments.
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