A Modular Approach toward Functionalized Three-Dimensional Macromolecules:  From Synthetic Concepts to Practical Applications

2003 ◽  
Vol 125 (3) ◽  
pp. 715-728 ◽  
Author(s):  
Anton W. Bosman ◽  
Robert Vestberg ◽  
Andi Heumann ◽  
Jean M. J. Fréchet ◽  
Craig J. Hawker
Author(s):  
Tianjiao Wang ◽  
Jun Zhao ◽  
Chuanxin Weng ◽  
Tong Wang ◽  
Yayun Liu ◽  
...  

Shape memory polymers (SMPs) that change shapes as designed by external stimuli have become one of the most promising materials as actuators, sensors, and deployable devices. However, their practical applications...


2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Wanzeng Kong ◽  
Jinshuai Yu ◽  
Ying Cheng ◽  
Weihua Cong ◽  
Huanhuan Xue

With 3D imaging of the multisonar beam and serious interference of image noise, detecting objects based only on manual operation is inefficient and also not conducive to data storage and maintenance. In this paper, a set of sonar image automatic detection technologies based on 3D imaging is developed to satisfy the actual requirements in sonar image detection. Firstly, preprocessing was conducted to alleviate the noise and then the approximate position of object was obtained by calculating the signal-to-noise ratio of each target. Secondly, the separation of water bodies and strata is realized by maximum variance between clusters (OTSU) since there exist obvious differences between these two areas. Thus image segmentation can be easily implemented on both. Finally, the feature extraction is carried out, and the multidimensional Bayesian classification model is established to do classification. Experimental results show that the sonar-image-detection technology can effectively detect the target and meet the requirements of practical applications.


1980 ◽  
Vol 7 (1) ◽  
pp. 93-104 ◽  
Author(s):  
A.W. Peterson ◽  
T. Blench

This paper, for river engineers and their environmental counterparts, presents and explains the origin and potential of four-dimensional charts that smooth most of the world's numerical data obtained from the equilibrium dimensions of sand rivers, gravel rivers, and laboratory flumes. These charts aim to provide a practical service comparable with that provided by factual plots on the comprehensive classic three-dimensional Stanton friction-factor diagram for circular pipes and clean Newtonian fluid. In the river problems, especially, the existence of different phases (whose transitions are not susceptible to formulation), the inadequacies of textbook theories even for simple phases, and the unavoidable imperfections of both field and laboratory measurements combine to prevent responsible design. The remedy is a graphing of total information backed by references from which its reliability and practicability can be assessed.The references have been chosen to contain principal information in the forms of: (i) usable photos, graphs, and tables; (ii) explanations free from specialized mathematics and speculative arguments; and (iii) papers with discussions, authors' replies, and further useful references (since a major reference list would be too long for this paper). Because condensation has had to be extreme the authors will be glad to attempt answers to discussions and questions on the subject matter, its practical applications, and its implications in teaching and research.


2018 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Yu Chen ◽  
Weipeng Lu ◽  
Yanchuan Guo ◽  
Yi Zhu ◽  
Haojun Lu ◽  
...  

In this work, five nanocrystalline first transition-metal (Ti, Mn, Co, Ni and Zn) oxide nanofibers were prepared by electrospinning and controlled calcination. The morphology, crystal structure, pore size distribution and specific surface area were systematically studied by scanning electron microscope (SEM), transmission electron microscope (TEM), surface and pore analysis, and thermo gravimetric analyzer (TGA). The results reveal that the obtained nanofibers have a continuously twisted three-dimensional scaffold structure and are composed of neat nanocrystals with a necklace-like arrangement. All the samples possess high specific surface areas, which follow the order of NiO nanofiber (393.645 m2/g) > TiO2 nanofiber (121.445 m2/g) > ZnO nanofiber (57.219 m2/g) > Co3O4 nanofiber (52.717 m2/g) > Mn2O3 nanofiber (18.600 m2/g). Moreover, the photocatalytic degradation of methylene blue (MB) in aqueous solution was investigated in detail by employing the five kinds of metal oxide nanofibers as photocatalysts under ultraviolet (UV) irradiation separately. The results show that ZnO, TiO2 and NiO nanofibers exhibit excellent photocatalytic efficiency and high cycling ability to MB, which may be ascribed to unique porous structures and the highly efficient separation of photogenerated electron-hole pairs. In brief, this paper aims to provide a feasible approach to achieve five first transition-metal oxide nanofibers with excellent performance, which is important for practical applications.


2017 ◽  
Vol 114 (18) ◽  
pp. 4613-4618 ◽  
Author(s):  
Dingchang Lin ◽  
Jie Zhao ◽  
Jie Sun ◽  
Hongbin Yao ◽  
Yayuan Liu ◽  
...  

Rechargeable batteries based on lithium (Li) metal chemistry are attractive for next-generation electrochemical energy storage. Nevertheless, excessive dendrite growth, infinite relative dimension change, severe side reactions, and limited power output severely impede their practical applications. Although exciting progress has been made to solve parts of the above issues, a versatile solution is still absent. Here, a Li-ion conductive framework was developed as a stable “host” and efficient surface protection to address the multifaceted problems, which is a significant step forward compared with previous host concepts. This was fulfilled by reacting overstoichiometry of Li with SiO. The as-formed LixSi–Li2O matrix would not only enable constant electrode-level volume, but also protect the embedded Li from direct exposure to electrolyte. Because uniform Li nucleation and deposition can be fulfilled owing to the high-density active Li domains, the as-obtained nanocomposite electrode exhibits low polarization, stable cycling, and high-power output (up to 10 mA/cm2) even in carbonate electrolytes. The Li–S prototype cells further exhibited highly improved capacity retention under high-power operation (∼600 mAh/g at 6.69 mA/cm2). The all-around improvement on electrochemical performance sheds light on the effectiveness of the design principle for developing safe and stable Li metal anodes.


2019 ◽  
Vol 19 (11) ◽  
pp. 7404-7409 ◽  
Author(s):  
Aihua Jing ◽  
Gaofeng Liang ◽  
Hao Shi ◽  
Yixin Yuan ◽  
Quanxing Zhan ◽  
...  

Three-dimensional (3D) graphene with high specific surface area, excellent conductivity and designed porosity is essential for many practical applications. Herein, holey graphene oxide with nano pores was facilely prepared via a convenient mild defect-etching reaction and then fabricated to 3D nanostructures via a reduction method. Based on the 3D architectures, a novel enzymatic hydrogen peroxide sensor was successfully fabricated. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to characterize the 3D holey graphene oxide architectures (3DHGO). Cyclic voltammetry (CV) was used to evaluate the electrochemical performance of 3DHGO at glassy carbon electrode (GCE). Excellent electrocatalytic activity to the reduction of H2O2 was observed, and a linear range of 5.0×10-8~5.0×10-5 M with a detection limit of 3.8×10-9 M was obtained. These results indicated that 3DHGO have potential as electrochemical biosensors.


2018 ◽  
Vol 844 ◽  
pp. 61-91 ◽  
Author(s):  
Weihua Li ◽  
Satish Kumar

The coating of discrete objects is an important but poorly understood step in the manufacturing of a broad variety of products. An important model problem is the flow of a thin liquid film on a rotating cylinder, where instabilities can arise and compromise coating uniformity. In this work, we use lubrication theory and flow visualization experiments to study the influence of surfactant on these flows. Two coupled evolution equations describing the variation of film thickness and concentration of insoluble surfactant as a function of time, the angular coordinate and the axial coordinate are solved numerically. The results show that surface-tension forces arising from both axial and angular variations in the angular curvature drive flows in the axial direction that tend to smooth out free-surface perturbations and lead to a stable speed window in which axial perturbations do not grow. The presence of surfactant leads to Marangoni stresses that can cause the stable speed window to disappear by driving flow that opposes the stabilizing flow. In addition, Marangoni stresses tend to reduce the spacing between droplets that form at low rotation rates, and reduce the growth rate of rings that form at high rotation rates. Flow visualization experiments yield observations that are qualitatively consistent with predictions from linear stability analysis and the simulation results. The visualizations also indicate that surfactants tend to suppress dripping, slow the development of free-surface perturbations, and reduce the shifting and merging of rings and droplets, allowing more time for solidifying coatings in practical applications.


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