Utilization of a proper metal–organic framework (MOF) template has recently attracted significant attention for the fabrication of high-performance supercapacitor electrodes; however, limited ...attention has been paid to the process of preparation of an excellent MOF template used to derive the anticipated electrode materials. Herein, a two-fold interpenetrating MOF with a microporous structure and multi-components, such as nickel, phosphorus, nitrogen, oxygen, and carbon, in the final framework was successfully constructed. The pristine sample could be directly utilized as a supercapacitor electrode material, which exhibited the moderate electrochemical capacitance of 979.8 F g −1 at the current density of 1 A g −1 . Using the simple treatment of one-step pyrolysis under a nitrogen atmosphere at different annealing temperatures (500 °C, 600 °C, 700 °C, and 800 °C), rare hierarchical Ni/P/N/C composites, denoted as Ni/P/N/C-500, Ni/P/N/C-600, Ni/P/N/C-700, and Ni/P/N/C-800, were derived from the parent MOF. The anticipated multi-components Ni, P, N, and O were uniformly incorporated into the carbon materials, which resulted in an excellent synergistic effect to improve the electrochemical energy storage performance. The morphologies and components of these derivatives were characterized via SEM, XPS, and XRD, indicating the uniform distribution of different components in the hybrid structures. The maximum specific capacitance for the Ni/P/N/C-500 electrode reached 2887.87 F g −1 at the current density of 1 A g −1 , which was superior to that of other hierarchical composites and established a new benchmark in the related field. The combination of several advantages, such as high surface area, even distribution, and ultra-high content of Ni/P/N/C components, in these derivatives ensured their high-performance in energy storage. The presented results fully demonstrate the unique advantage of utilizing the pre-designed MOFs as a template to prepare hybrid materials used as potential electrode-active materials in supercapacitors and provide an efficient route to fabricate superior-performance energy-storage devices.
Kinetic study of the step-growth polymerization of hydroxyl-terminated poly(dimethylsiloxane) (PDMS) and triisocyanate has been done in this work. Kinetic Monte Carlo simulations are performed to ...understand the experimental investigation of the cross-linked network formation. This approach enables us to afford a visualization of the entire network formation in detail and evaluate its characteristic properties. A comparison between the current simulation results and that from classical theories (e.g., Flory and Macosko–Miller theoretical calculations) is done. In addition, the Cole–Poehlein diffusion model based on the free volume theory, involving a parallel summation of the chemical and diffusional rate coefficients, is used to describe the effect of diffusion-controlled mechanism on polymerization. Moreover, the effect of experimental conditions, such as the ratio of NCO/OH and the molar mass of PDMS, on network formation kinetics is also investigated. The simulation results demonstrate that the NCO/OH ratios within the range of 1–1.2 and PDMS with lower molar mass are preferred to prepare a polymer network with a high cross-linking density. It is believed that the current kinetic modeling provides a way for better understanding the kinetics and optimizing the experimental conditions.
A challenge for high‐impact polystyrene (HIPS) production and design is the more accurate and low computational cost prediction of the phase separation and phase inversion conversion, the first ...conversion determining the onset of the two‐phase system and the second conversion defining the pathway toward a complex, for example, salami‐like morphology. In this work, a two‐phase deterministic method of moments (MoM) model running in several minutes is therefore developed in the intermediate styrene conversion range (up to around 30%), considering for simplicity only diffusional limitations on termination on an average basis. It is showcased that the phase separation conversion can be taken as 2 m%, and the phase inversion conversion should be calculated by algebraic means. Interestingly, the latter conversion varies with the initial reaction conditions either on a time basis (e.g., variation of initial radical concentration) or both a time and conversion basis (e.g., relative contribution of rubber and St partitioning coefficient). A comparison with the commonly used pseudo‐homogeneous MoM model reveals that by accounting for mass transfer in a more representative two‐phase model, the amount of monomer consumed is slightly reduced, the grafting efficiency decreases with increasing conversion instead of increasing, and the styrene composition in the graft copolymer decreases. The current work additionally puts forward two‐phase MoM data to facilitate future benchmarking with other (stochastic) modeling approaches and enables kinetic insights into heterogeneous grafting polymerization, further promoting the production of multiphase industrial polymer products.
Deep learning methods have great potential to predict tumor characterization, such as histological diagnosis and genetic aberration. The objective of this study was to evaluate and validate the ...predictive performance of multimodality imaging-derived models using computer-aided diagnostic (CAD) methods for prediction of MDM2 gene amplification to identify well-differentiated liposarcoma (WDLPS) and lipoma.
All 127 patients from two institutions were included with 89 patients in one institution for model training and 38 patients in the other institution for external validation between January 2012 and December 2018. For each modality, handcrafted radiomics analysis with manual segmentation was applied to extract 851 features for each modality, and six pretrained convolutional neural networks (CNNs) extracted 512-2048 deep learning features automatically. Extracted imaging-based features were selected via univariate filter selection methods and the recursive feature elimination algorithm, which were then classified by support vector machine for model construction. Integrated with two significant clinical variables, age and LDH level, a clinical-radiological model was constructed for identification WDLPS and lipoma. All differentiation models were evaluated using the area under the receiver operating characteristics curve (AUC) and their 95% confidence interval (CI).
The multimodality model on deep learning features extracted from ResNet50 algorithm (RN-DL model) performed great differentiation performance with an AUC of 0.995 (95% CI 0.987-1.000) for the training cohort, and an AUC of 0.950 (95% CI 0.886-1.000), accuracy of 92.11%, sensitivity of 95.00% (95% CI 73.06-99.74%), specificity of 88.89% (95% CI 63.93-98.05%) in external validation. The integrated clinical-radiological model represented an AUC of 0.996 (95% CI 0.989-1.000) for the training cohort, and an AUC of 0.942 (95% CI 0.867-1.000), accuracy of 86.84%, sensitivity of 95.00% (95% CI 73.06-99.74%), and specificity of 77.78% (95% CI 51.92-92.63%) in external validation.
Imaging-based multimodality models represent effective discrimination abilities between WDLPS and lipoma via CAD methods, and might be a practicable approach in assistance of treatment decision.
Robotic grinding is a promising technique to generate the final shape of blades. It can relieve human from participating in dirty and noisy environments, improve product quality, and lower production ...costs. One important task in robotic grinding is 3-D shape matching. However, existing matching methods do not consider the requirements associated with different grinding allowances, which can potentially lead to an unstable grinding force. This paper proposes a novel shape matching method for robotic grinding. The goal is to define a new objective function considering different allowance weights for stable grinding, and address incorrect shape matching from the missing points or uneven density points. The main contribution of this paper is the application of variance minimization to construct an objective function, from which the required shape matching parameters are iteratively calculated. This method balances the contributions of all the measured points, weighs the allowances for the pressure and suction surfaces of a blade, and avoids incorrect matching tendencies for high-density points. It is advantageous to maintaining a relatively stable grinding force. The effectiveness of this method is verified through simulations and scanning/grinding experiments of different blades.
Depolymerization by chain‐end scission enables ideally full recovery of monomers, which is considered as a promising route for polymer recycling. Despite attractive experimental achievements, ...insightful depolymerization kinetic modeling study is capable of providing information for better understanding polymer degradation process and reactor design in polymer industry. Herein, an improved analytical solution for depolymerization by chain‐end scission is derived and validated by numerical exact solution. The strength of the as‐derived analytical solution lies on its capability of capturing depolymerization kinetics of polymers with large degrees of polymerization and different initial distributions (e.g., Gamma, monodisperse, Poisson, Flory‐Schulz, exponential, and log‐normal distributions). Additionally, the changes in average properties of polymer are accessed by using a hybrid method based on the method of moment (MoM) and the improved analytical solution considering dimers in chain‐end scission process for the first time. Finally, kinetic insights into depolymerization of self‐immolative polymers are also gained by the MoM‐based model in parallel with two sets of experimental data. This work offers simulation protocols for a profound understanding of depolymerization kinetics and inspecting molecular properties during depolymerization.
Anthropogenic activities, such as sewage irrigation and application of pesticides and fertilizers, are the main cause of chromium (Cr) contamination in agricultural soils. Cr contamination reduces ...soil quality and threatens environmental and human health. Conventional Cr measurement methods, although accurate, involve complex sample processing steps and sophisticated laboratory analysis, which are time-consuming, costly, and often environmentally unfriendly. X-ray fluorescence (XRF) and visible near-infrared (vis–NIR) spectroscopy have been recognized as alternatives to measure soil heavy metal contamination in a cheap, fast, non-destructive, and environmentally conscious manner. In this study, 301 paddy soil samples from Fuyang, Zhejiang Province, China were used to explore the feasibility and effectiveness of XRF and vis–NIR spectra separately and in combination for estimating the soil Cr content. Two strategies, including outer-product analysis (OPA) and Granger–Ramanathan averaging (GRA), were used to combine the spectra and spectral models, respectively, from the two instruments (sensor fusion). Partial least-squares regression (PLSR) was used to train the models using a single sensor (XRF or vis-NIR spectra) and OPA fused spectra. Fifty boot straps were used to assess the uncertainty of the predictions for the aforementioned models. The results indicated that XRF spectra performed better than vis–NIR spectra for predictions of Cr content, with a Lin's concordance correlation coefficient (ρc) of 0.83, a root mean square error (RMSE) of 8.80, and a ratio of prediction derivation (RPD) of 1.75. Sensor fusion by OPA gave the highest prediction accuracy with a ρc of 0.90, RMSE of 6.80, and RPD of 2.30. The sensor fusion by GRA gave similar results with a ρc of 0.88, RMSE of 7.40, and RPD of 2.13. The predictions using both methods (OPA and GRA) were acceptable when considering the standard deviation of differences (SDD = 4.23). This suggests that OPA and the GRA sensor fusion methods are efficient and accurate for rapid measurement of Cr and provide a way forward for using these technologies for fast, sensor-based soil characterization.
•X-ray fluorescence and vis-NIR spectra were used to predict paddy soil Cr content.•Two sensor fusion techniques; OPA and GRA were compared for prediction accuracy.•OPA and GRA fusion were able to improve the prediction of soil Cr.
This paper is devoted to the investigation of the transverse vibration and dynamic stability of the axially moving viscoelastic plate with two opposite edges simply supported and other two opposite ...edges with simply supported or free. By considering the Kelvin–Voigt model of viscoelasticity, the equation of motion of the plate is derived. The normalized power series method is employed to obtain the complex eigen equations for the axially moving viscoelastic plate. The variation relationship between the first three complex frequencies of the system and the dimensionless axially moving speed with different aspect ratio and dimensionless delay time are analyzed. The results show that the dimensionless delay time, axially moving speed as well as the aspect ratio have remarkable effects on dynamic behaviors and stability of the axially moving viscoelastic plate.
•The governing equation of the axially moving viscoelastic plate is derived.•The complex eigen equations are obtained by the normalized power series method.•The factors that affect the stability of the plate are studied.
In this work, a modeling study of the average and distributed properties of hyperbranched polymers has been performed. A kinetic Monte Carlo algorithm was developed to trace the formation of ...hyperbranched structures by three typical synthetic routes: (i) polycondensation of AB2-type monomers; (ii) self-condensing vinyl polymerization (SCVP) of AB-type monomers; and (iii) polycondensation of A2 and B3 monomers. Model validation was performed with experimental data. Significantly, the expression of the degree of branching (DB) was revised to make it sensitive to cyclic defects. Critical factors such as cyclization and non-equal reactivity were analyzed for each case, summarizing that cyclization can cause a decrease in dispersity and an increase in linear unit reactivity can improve the average degree of branching ( D B ̅ ). Specifically, for SCVP, the relative reactivity of two active sites and the composition of the inimer and monomer determine how much the linear dendritic hybrid can be branched. Additionally, the D B ̅ can also be increased as much as possible by delaying the gelation for the A2 and B3 system. This work contributes to the study of the DB distribution of hyperbranched polymers with cyclic defects and provides theoretical guidance for the design of hyperbranched structures.
