Hollow Bio-derived Polymer Nanospheres with Ordered Mesopores for Sodium-Ion Battery

Bio-inspired hierarchical self-assembly provides elegant and powerful bottom-up strategies for the creation of complex materials.However,the current self-assembly approaches for natural bio-compounds often result in materials with limited diversity and complexity in architecture as well as microstructure.Here,we develop a novel coordination polymerization-driven hierarchical assembly of micelle strategy,using phytic acid-based natural compounds as an example,for the spatially controlled fabrication of metal coordination bio-derived polymers.The resultant ferric phytate polymer nanospheres feature hollow architecture,ordered meso-channels of^12 nm,high surface area of 401 m2 g−1,and large pore volume of 0.53 cm3 g−1.As an advanced anode material,this bio-derivative polymer delivers a remarkable reversible capacity of 540 mAh g−1 at 50 mA g−1,good rate capability,and cycling stability for sodium-ion batteries.This study holds great potential of the design of new complex bio-materials with supramolecular chemistry.

General synthesis of hollow mesoporous conducting polymers by dual-colloid interface co-assembly for high-energy-density micro-supercapacitors

Rational design and precise regulation over the morphology, structure, and pore size of functional conducting mesoporous polymers with enriched active sites and shorten electron–ion transport pathway are extremely important for developing high-performance micro-supercapacitors (MSCs), but still remain a great challenge. Herein, a general dual-colloid interface co-assembly strategy is proposed to fabricate hollow mesoporous polypyrrole nano-bowls (mPPy-nbs) for high-energy-density solid-state planar MSCs. By simply adjusting the size of block copolymer micelles, the diameter of polystyrene nanospheres and the amount of pyrrole monomer, mesopore size of the shell, void and shell thickness of mPPy-nbs can be simultaneously controlled. Importantly, this strategy can be further utilized to synthesize other hollow mesoporous polymers, including poly(tris(4-aminophenyl)amine), poly(1,3,5-triaminobenzene) and their copolymers, demonstrative of excellent universality. The structurally optimized mPPy-nb exhibits high specific surface area of 122 m^(2) g^(−1)and large capacitance of 225 F g^(−1) at 1 mV s^(−1). Furthermore, the MSCs assembled by mPPy-nbs deliver impressive volumetric capacitance of 90 F cm^(−3) and energy density of 2.0 mWh cm^(−3), superior to the most reported polymers-based MSCs. Also, the fabricated MSCs present excellent flexibility with almost no capacitance decay under varying bending states, and robust serial/parallel self-integration for boosting voltage and capacitance output. Therefore, this work will inspire the new design of mesoporous conducting polymer materials toward high-performance microscale supercapacitive devices.

A SIMPLE METHOD FOR PREDICTION OF THE REDUCED SCATTERING COEFFICIENT IN TISSUE-SIMULATING PHANTOMS

This paper proposes a method for predicting the reduced scattering coefficients of tissuesimulating phantoms or the desired amount of scatters for producing phantoms according to Mie scattering theory without measurements with other instruments.The concentration of the scatters TiO2 particles is determined according to Mie theory calculation and added to transparent host epoxy resin to produce phantoms with different reduced scattering coefficients.Black India Ink is added to alter the absorption coefficients of the phantoms.The reduced scattering coefficients of phantoms are measured with single integrating sphere system.The results show that the measurements are in direct proportion to the concentration of TiO2 and have identical with Mie theory calculation at multiple wavelengths.The method proposed can accurately determine the concentration of scatters in the phantoms to ensure the phantoms are qualified with desired reduced scattering coefficients at specified wavelength.This investigation should be possible to manufacture the phantom simply in reasonably accurate for evaluation of biomedical optical imaging systems.

Mesoporous polymers:soft-template self-assembly synthesis and applications

Mesoporous polymers combine the advantages of polymer materials(abundant polar functional groups,lightweight,flexibility,and processability)and mesoporous structures(high specific surface area,adjustable pore structure,and large pore volume);hence,they have great application potential in sensing,adsorption,catalysis,energy storage,biomedicine,etc.Currently,developing advanced synthetic strategies for mesoporous polymers and investigating their intrinsic applications have become hot research topics.Soft-template-based self-assembly is regarded as a promising approach for synthesizing mesoporous polymers.This work reviews recent progress in the synthetic strategy for producing various mesoporous polymers using soft-template selfassembly,focusing on the synthesis of conductive polymers,phenol-based polymers,and resin-based polymers and their potential applications.Finally,perspectives on future applications of mesoporous polymers,along with a few challenges that need to be resolved,are also discussed in this review.

Emerging hierarchical mesoporous materials of covalent organic frameworks

Benefiting from abundant exposed active sites,minimized diffusion resistance of guest molecules,facilitated mass transfer process and enhanced storage capacity,covalent organic frameworks(COFs)have gained widespread scientific attention[1–4].Further construction of mesopores regarding pore engineering(pore size,pore geometry,pore volume,and framework compositions)in COFs can improve mass transport,accessibility as well as size-selectivity of the special guest moieties,thus exhibiting potential in catalysis,energy storage and separation and so on[5,6].

Self-filtering illumination source and application in fluorescence imaging

To date,fluorescence imaging systems have all relied on at least one beam splitter(BS)to ensure the separation of excitation light and fluorescence.Here,we reported SiO2=TiO2 multi-layer long pass filter integrated GaN LED.It is considered as the potential source for imaging systems.Experimental results indicate that the GaN LED shows blue emission peaked at 470.3 nm and can be used to excite dye materials.Integrating with a long pass filter(550 nm),the light source can be used to establish a real-time fluorescence detection for dyes that emit light above 550 nm.More interestingly,with this source,a real-time imaging system with signature words written with the dyes,such as‘NJUPT’,can be converted into CCD images.This work may lead to a new strategy for integrating light sources and BS mirrors to build mini and smart fluorescence imaging systems.

Construction of a computational MDCT model for simulations of the detector signals

Objective:To develop a computational model of a multi-detector CT scanner(MDCT),which could be used to simulate the signal of each detector element in the MDCT by using the Monte Carlo method.Methods:The CT scanner was modelled,including the X-ray source,the bowtie filter,the collimator,the couch and the detector panel.Under a general scanning condition,the signal in each detector element was simulated based on the model by using the MCNPX code.Both the energy spectra at different tube voltages and energy deposition in the detector panel at different collimations were simulated to test the robustness of the MDCT model built in this study.Furthermore,the simulated signals in each detector element were compared with their recorded signals.The accuracies were evaluated by the relative root mean square error(RRMSE)and the structural similarity(SSIM)for each detector element and the whole detector panel,respectively.Results:The simulated energy spectra before and after passing through the phantom and simulated energy deposition in the detector panel were rational.In the scan range from the apex of lung to pubic symphysis,the RRMSE of the 18 axial projections ranged from 0.02 to 0.17,with an average of 0.08.And the SSIMs were calculated to be 0.979 and 0.976 for projections with the largest peak signal and the smallest peak signal,respectively.Conclusions:The computational model of the MDCT developed in this study is accurate and successful,it is helpful for further accurate simulations of the radiation dose and image quality of the MDCT.

Experimental investigation on dynamic response of flat blades with underplatform dampers

One test rig with three blades and two Under-Platform Dampers(UPDs) is established to better understand the dynamical behavior of blades with UPDs. A pre-loaded spring is used to simulate the centrifugal load acting on the damper, thereby achieving continuous adjustment of the pressing load. UPDs with different forms, sizes and materials are carefully designed as experimental control groups. Noncontact measurement via a laser Doppler velocimeter is employed and contact excitation which is performed by an electromagnetic exciter is adopted to directly obtain the magnitude of the excitation load by a force sensor mounted on the excitation rod. Particular attention is paid to the influence of the contact status of the contact surfaces, e.g. the pressure-sensitive paper is used to measure the effective contact area of the UPDs. The experimental variables are selected as the centrifugal force, the amplitude of the excitation force, the damper mass, the effective contact area, and the damper material. The Frequency Response Function(FRF) of the blade under different experimental parameters is obtained by slow frequency sweep under sinusoidal excitation to study the influence of each parameter on the dynamic characteristics of the blade and the mechanism analysis is carried out combined with the experimental results.

Two-dimensional mesoporous sensing materials

Two-dimensional mesoporous materials combing ultrathin nanosheet morphology with well-defined mesoporous structures,are now emerging and becoming increasingly important for their promising applications in energy storage,electronic devices,electrocatalysts and so on.Here,we synthesized a kind of polypyrrole-based two-dimensional mesoporous materials with uniform pore size,ultrathin thickness and high surface area.Serving for electrochemical NH3 sensor,they exhibited a fast response and high sensitivity.Therefore,our study would promote much interest in design of new materials for gas sensor applications.