查找使用阿拉丁产品的科研文献

Space-confinement-induced synthesis of hierarchically nanoporous carbon nanowires for the enhanced electrochemical reduction of oxygen

Jiaoxing Xu,Qiangmin Yu,Lunhui Guan

Hierarchically nanoporous N-doped carbon nanowires (N-CWs) were prepared by a novel space-confinement-induced assembly strategy, for which nitrogen-enriched pyrimidine and anodic aluminium oxide (AAO) template bearing metal oxides are employed as precursor and nanoscale channels, respectively, and the Fe/Co metal oxide not only blocks the AAO surface from the original surface-templating carbonization, but also introduces nanoporosity with acid etching. Thus-obtained carbon nanowires composed of N-doped graphene-like carbon nanosheets not only contain a high N content (up to ∼12%), but also possess a hierarchically meso/microporous structure (∼1.3 cm3 g−1) with high specific surface area (∼455 m2 g−1). This protocol allows for the simultaneous optimization of graphitization, porous structure and surface functionalization. As a result, the prepared N-CWs demonstrate an attractive electrocatalytic capability towards oxygen reduction reaction (ORR). Specifically, in addition to the improved kinetic current density and overpotential, the N-CWs prepared at 700 °C show the optimized ORR performance with an electron-transfer number of ∼4.0, which very close to that of a commercial Pt/C catalyst.

Design Space Development for the Extraction Process of Danhong Injection Using a Monte Carlo Simulation Method

Xingchu Gong,Yao Li,Huali Chen,Haibin Qu

A design space approach was applied to optimize the extraction process of Danhong injection. Dry matter yield and the yields of five active ingredients were selected as process critical quality attributes (CQAs). Extraction number, extraction time, and the mass ratio of water and material (W/M ratio) were selected as critical process parameters (CPPs). Quadratic models between CPPs and CQAs were developed with determination coefficients higher than 0.94. Active ingredient yields and dry matter yield increased as the extraction number increased. Monte-Carlo simulation with models established using a stepwise regression method was applied to calculate the probability-based design space. Step length showed little effect on the calculation results. Higher simulation number led to results with lower dispersion. Data generated in a Monte Carlo simulation following a normal distribution led to a design space with a smaller size. An optimized calculation condition was obtained with 10000 simulation times, 0.01 calculation step length, a significance level value of 0.35 for adding or removing terms in a stepwise regression, and a normal distribution for data generation. The design space with a probability higher than 0.95 to attain the CQA criteria was calculated and verified successfully. Normal operating ranges of 8.2-10 g/g of W/M ratio, 1.25-1.63 h of extraction time, and two extractions were recommended. The optimized calculation conditions can conveniently be used in design space development for other pharmaceutical processes.

Rapid synthesis of self-standing covalent organic frameworks membrane via polyethylene glycol-assisted space-confined strategy

Guoxiu Wang,Yonglei Chen,Congjie Pan,Hongli Chen,Sanyuan Ding,Xingguo Chen

Owing to their high specific surface area , tunable pore sizes, excellent chemical/thermal stability and ability to allow easy modification of the nature of the surface, covalent organic frameworks (COFs) have shown great promise in membrane separation . However, until now, rapid preparation of self-standing COFs membrane has still been a great challenge. In this work, a polyethylene glycol-assisted space-confined strategy for rapid and simple synthesis of imine-linked self-standing COF (TB-DA COF) membranes was developed for the first time. By using this strategy, the molecular organic building unit 1,3,5-tri-(4-aminophenyl)benzene (TB) is confined in a thin layer of polyethylene glycol in conjunction with molecular organic building unit 2,5-dimethoxyterephthalaldehyde (DA). Therefore, the condensation reaction between TB and DA can occur directly without slow diffusion process. In addition, the amorphous-to-crystalline interconversion process can be completed rapidly. Based on this, the imine-based TB-DA COF membrane with high crystallinity can be synthesized within 2 min, which has been the fastest strategy for preparation of COFs membrane to date. The synthesized TB-DA COF 2 membrane showed an excellent rejection (>96%) for dye molecules. This work opens a new fabrication route for COF-based membranes.

Confined synthesis of ultrafine ZrO2 anchoring composites in switchable and microchannel-like space for fluoride removal

Danqing Shen,Qian Du,Pan Wang,Yongquan Zhou,Jianming Pan

The continuous phase films in high internal phase emulsions (HIPEs), which seems to be a microchannel-like space, are benefit for confined synthesis of ultrafine adsorbent. Herein, switchable and microchannel-like space in the continuous phase of oil-in-water HIPEs is developed for fabricating ultrafine ZrO 2 anchoring cross-linked enzyme aggregates (CLEAs-ZrO 2 ), and then as-prepared composites were applied as defluoridation adsorbent. Bis(3-aminopropyl)tetramethyldisiloxane oleic acid surfactant (BTOA) can realize reversible emulsification and demulsification in response to CO 2 /N 2 switch, endowing with simple collection of products and continuous preparation. This confinement effect is expected of resulting in a 28 % increase in adsorption capacity and 33 % reduction in synthesis time. In addition, the adsorption capacity of CLEAs-ZrO 2 is nearly 4.2 times higher than that of commercially available defluoridants. In fluorine-containing industrial wastewater, the removal efficiency of fluoride ion (F - ) reaches 93 %, and the corresponding partition coefficients ( K d ) achieves the value of 31.1 L g −1 . By analyzing with XPS spectra and in-situ FT-IR spectroscopy, a strong Zr-F bonding interaction between CLEAs-ZrO 2 and F - in the solution boosts this specific adsorption. This work presents a novel method for constructing switchable confinement system, but also offers a promising defluoridation adsorbent for industrial effluents.

Evaluation and Optimization of Refuge Green Space in the Central Area of Tianjin for Geological Disasters

Yilun Cao,Yuhan Guo,Chang Wang,Yunyuan Li

Refuge Green Space (RGS) plays roles in both rapid evacuation and short-term resettlement in response to sudden natural hazards, especially geological disasters. As a result, its evaluation and location optimization are crucial for the development of sustainable cities. In this study, the Three-Step Floating Catchment Area Method (3SFCA) and Moran’s I index were used as measurement models. The rapid evacuation and short-term resettlement capacity of RGS were evaluated by calculating accessibility with 5, 10, 15 and 30 min of walking. The purpose of this study was to quantitatively evaluate the supply capacity of RGS in the central area of Tianjin and to provide recommendations for future additions to RGS. The results show that over 80% of the research area exhibited relatively poor service capacity within a 5–10 min walking distance, while less than 20% exhibited relatively good service capacity. Within a 15–30 min walking distance, approximately 60% of the study area was not well served by the RGS, while approximately 40% was well served. In conclusion, the layout of RGS in the central area of Tianjin exhibits unevenness and polarization of phenomena, and the supply of different categories of RGS varies widely. There is an insufficient supply of Emergency Sheltered Green Space and Temporary Sheltered Green Space, and that which is available is difficult to reach within 5–10 min. The coverage capacity of Disaster Prevention Park Space is relatively good, essentially covering the entire study area within a 15–30 min walking distance; however, the service capacity is average. Based on these conclusions, areas in which the RGS supply was weak were identified, and future potential RGS additions were identified in conjunction with the Green Space System Plan.

Deep-Blue Through-Space Charge-Transfer MR-TADF Emitters With Anthracene Linkers for Narrowband Fluorescent OLEDs

Xiaoge Song,Cangyu Wang,Xiongkai Tang,Maggie Ng,Season Si Chen,Man-Chung Tang

Multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters are attractive candidates for high-definition OLED displays owing to their narrowband emission and high efficiency. However, most reported through-space charge-transfer (TSCT) MR-TADF compounds emit in the green region and suffer from limited operational stability, leaving deep-blue, narrowband MR-TADF emitters underexplored. Herein, we report a series of TSCT MR-TADF emitters based on an anthracene linker and U-shaped molecular confinement. By incorporating an extended anthracene bridge, carbazolyl substitution, and targeted deuteration, this molecular design modulates TSCT character, suppresses high-frequency vibrational modes, and enhances molecular rigidity. These compounds exhibit saturated blue to green emission with photoluminescence quantum yields (PLQYs) over 90%, full widths at half maximum (FWHMs) of approximately 30 nm in thin films, and reverse intersystem crossing rate constants (k RISC ) values up to 1.2 × 10 5 s −1 . D-U-OBN-tCz enabled a deep-blue non-sensitized TADF OLED with an EQE of up to 20% and CIE coordinates of (0.15, 0.07). These findings demonstrate an effective molecular design platform for realizing color-pure and operationally stable deep-blue MR-TADF emitters for OLED displays.

Preparation and Performance Investigation of a Novel Microcapsule Fire Extinguishing Agent for Confined Space Fire Suppression

Zhe Wen,Lingfeng Xiong,Yingchu Wang,Zihan Wang,Honglai Xue,Zhe Tu

A novel microcapsule fire extinguishing agent was prepared through interfacial polymerization method, using HFE-7300 as the core material and SPUA as the wall material. The microcapsule fire extinguishing agent obtained under the optimal conditions (HFE-7300@SPUA) exhibited relatively well-defined morphology, successful core-shell encapsulation, high encapsulation efficiency and excellent thermal stability. The SPUA-based wall material of microcapsule ruptures precisely upon abnormal ambient temperature and the encapsulated HFE-7300 spills out rapidly to extinguish fires, thus achieving efficient fire suppression for the fires in confined spaces at the incipient fire stage. The addition of HFE-7300@SPUA effectively reduced the maximum temperature, the average heating rate and the self-extinguishing time for the free combustion of n -heptane. The fire suppression mechanism of HFE-7300@SPUA characterized by active defense properties is particularly suitable for combating sudden chain-reaction fires in precise and confined spaces. HFE-7300@SPUA holds great practical application potential in fire safety protection of lithium-ion batteries and electrical equipments.

Machine Learning-Assisted Intelligent Gesture Recognition and VR Space Communication Smart-Glove System Using Strain Sensors

Shixiang Lin,Chengfeng Sun,Yuhan Huang,Bin Cheng,Heng Luo,Minglu Zhu,Tao Chen,Fengxia Wang,Lining Sun

Gesture recognition based on machine-learning approaches plays a pivotal role in advancing Human–machine Interaction (HMI) and robotics. Typical smart glove solutions with flexible sensors can only recognize discrete gestures, not sentences, and fail to meet the daily communication needs of signers. Moreover, current interfaces for displaying recognition outcomes are mostly confined to smartphones or computers, limiting seamless communication between signers and non-signers. Herein, we propose an artificial intelligence hand gesture recognition HMI system consisting of an intelligent sensing glove, a machine learning module, and a virtual reality interface. This system represents a substantial leap forward in gesture recognition technology with adaptability, comfort, and lightweight construction. Enhanced by advanced machine learning algorithms, it achieves remarkable accuracy across a diverse range of gestures—including 10 numeric gestures, 14 alphabetic phrases, and 5 sentence patterns—boasting 99.5% accuracy for numeric and 99.3% accuracy for alphabetic recognition and an impressive 98.8% accuracy for sentence-level interpretation. The system projects recognition results into a virtual space, translating gestures into text in real time. This functionality facilitates not only human–machine interaction but also inter-human communication, particularly bridging the gap between signers and non-signers. It underscores its potential for practical implementation in next-generation HMI systems.

Influence of the semiconductive composites doped with Li4Ti5O12 on space charge injection in low-density polyethylene

Yin Hongxia,Zhao Shiyi,Hao Chuncheng,Lei Qingquan

Space charge accumulation in the insulating layers of high voltage direct current cables is the key factor that leads to their degradation and limits the operation safety. Hence, it is necessary to effectively inhibit space charge injection to these layers. In this study, a new method is proposed to suppress the charge injection to cable insulation layer: a certain amount of Li 4 Ti 5 O 12 nanopowder is doped into the semiconductive screen to enhance the internal conductive network and homogenize the electric field. The influences of Li 4 Ti 5 O 12 particles in the semiconductive composite screen on the positive temperature coefficient effect and space charge injection process are explored. The obtained results reveal that the charge quantity in the insulation layer corresponding to the minimum peak resistivity is reduced by 49.7%, 58.9%, and 46.9% after polarization at a Li 4 Ti 5 O 12 content of 4 wt% and electric field strengths of 10, 20, and 30 kV/mm, respectively.

In Situ Encapsulation of Pt Nanoparticles within Pure Silica TON Zeolites for Space-Confined Selective Hydrogenation

Junjie Tang,Peiwen Liu,Xiaoling Liu,Lei Chen,Haimeng Wen,Yu Zhou,Jun Wang

Straightforward encapsulation of Pt clusters (∼2 nm) into the pure silica TON-type zeolite (ZSM-22) was reached in a dry gel conversion route, where the ionic liquid template was removed via the hydrocracking-calcination-reduction approach. The obtained Pt@ZSM-22 series possessed high crystallinity, large surface area, and ultrafine Pt clusters inside the zeolite crystals. They exhibited remarkable activity in the semi-hydrogenation of phenylacetylene into styrene; the lead sample with 0.2 wt % Pt loading afforded a large turnover number up to 117,787. The preferential high affinity of the pure silica ZSM-22-encapsulated Pt clusters toward the substrate phenylacetylene rather than the hydrogenated product was derived from the unique space-confinement effect of zeolite microchannels, which is responsible for such excellent performance.

Polymerization of MMA by RATRP in the confined space of polyHIPEs with varied internal phase contents

Chen Mingsen,Sun Fameng,Xu Wangfa,Zhou Li,Zhang Faai

A series of polymerized high internal phase emulsion (polyHIPE) monoliths with internal phase contents varying from 82.5 to 94.0 % were synthesized. The limited spaces of the polyHIPE were used as reactors to polymerize methyl methacrylate (MMA) by reverse atom transfer radical polymerization (RATRP). The main purpose of this research was to investigate the effect of limited spaces of polyHIPE on RATRP polymerization. The monoliths before and after MMA polymerization and PMMA obtained in the polyHIPE were characterized by scanning electron microscopy, gel permeation chromatography, Fourier transform infrared spectroscopy, thermogravimetry analysis, hydrogen nuclear magnetic resonance, and differential scanning calorimetry. The results suggested that the monomer MMA had polymerized in the polyHIPE. Compared with PMMA by RATRP without confined space, the molecular weight, initial thermal decomposition temperature, glass transition temperature ( T g ), and the isotacticity of the PMMA obtained from polyHIPE were increased significantly and the molecular weight distribution broadened. The increase in the internal phase contents increased the numbers of the cavities and windows, whereas the molecular weight, molecular weight distribution, and T g of the PMMA obtained from different polyHIPEs did not change much.

Effects of trap density on space charge suppression of block polypropylene/AI2O3 composite under high temperature

Chong Zhang,Jun-Wei Zha,Hong-Da Yan,Wei-Kang Li,Yong-Qiang Wen,Zhi-Min Dang