具有航空航天特色的高分子化学本研一体化教学探索

本文对如何在航空航天特色背景下进行高分子化学课程的本研一体化教学,进行了教学探索和教学实践,建立了具有航空航天特色的层次化、模块化的高分子化学课程体系。结果表明以上教学改革在人才培养中兼顾高分子通用知识和行业专业知识,促进了具有航空航天化学专业特色的毕业生培养,在学生就业、竞赛成绩等方面成效显著。

Overview of Position Servo Control Technology and Development of Voice Coil Motor

Voice coil motor(VCM) is a special direct drive linear motor, which can convert electric energy directly into mechanical energy without the use of transmission mechanism. VCM has the advantages of simple structure, good rigidity, fast response, silence, high linearity, no cogging force, no pulsation et al. It is widely used in the field of high-precision control. This paper reviews and summarizes the results of VCM research conducted by scholars from various countries, and summarizes the general situation of VCM servo control technology. Firstly, a basic description of VCM’s mathematical model and common control mechanisms is provided. The benefits, drawbacks, and application of control techniques in the field of VCM are all explored in detail;At the same time, the methods to improve control strategy are proposed;Then, combined with the analysis and research of scholars in various countries on VCM, the problems of difficult to establish accurate model, friction disturbance and mechanical vibration of VCM and the solutions to the corresponding problems are summarized;Finally, a summary of VCM’s application fields is provided.

SCancerRNA:Expression at the Single-cell Level and Interaction Resource of Non-coding RNA Biomarkers for Cancers

Non-coding RNAs(ncRNAs)participate in multiple biological processes associated with cancers as tumor suppressors or oncogenic drivers.Due to their high stability in plasma,urine,and many other fluids,ncRNAs have the potential to serve as key biomarkers for early diagnosis and screening of cancers.During cancer progression,tumor heterogeneity plays a crucial role,and it is particularly important to understand the gene expression patterns of individual cells.With the development of single-cell RNA sequencing(scRNA-seq)technologies,uncovering gene expression in different cell types for human cancers has become feasible by profiling transcriptomes at the cellular level.However,a well-organized and comprehensive online resource that provides access to the expression of genes corresponding to ncRNA biomarkers in different cell types at the single-cell level is not available yet.Therefore,we developed the SCancerRNA database to summarize experimentally supported data on long ncRNA,microRNA,PIWI-interacting RNA,small nucleolar RNA,and circular RNA biomarkers,as well as data on their differential expression at the cellular level.Furthermore,we collected biological functions and clinical applications of biomarkers to facilitate the application of ncRNA biomarkers to cancer diagnosis,as well as the monitoring of progression and targeted therapies.SCancerRNA also allows users to explore interaction networks of different types of ncRNAs,and build computational models in the future.SCancerRNA is freely accessible at http://www.scancerrna.com/BioMarker.

Porous block copolymer films with self-adjustable optical transmittance and passive radiative cooling

As an energy-free cooling technique,radiative cooling has garnered significant attention in the field of energy conservation.However,traditional radiative cooling films often possess static optical properties and their inherent opacity limits their applications in building such as windows.Therefore,there exists a requirement for passive radiative cooling films endowed with adjustable transmittance.Here we report the porous block copolymer films with self-adjustable optical transmittance and passive radiative cooling.In a result,the film exhibited a high solar reflectance(0.3-2.5μm)of 96.9%and a high infrared emittance(8-13μm)of 97.9%.Outdoor experiments demonstrated that the film surface temperature was 6.6℃lower than ambient temperature,with a cooling power of 104.8 W·m^(-2).In addition,the film’s transmittance can be regulated by altering the polarity of the post-processing solvent,providing an effective approach for regulating indoor light intensity and thermal balance,thereby enhancing the applicability of radiative cooling.

Model-based investigation on building thermal mass utilization and flexibility enhancement of air conditioning loads

Building air conditioning systems(ACs)can contribute to the stable operation of power grids by participating in peak load shaving programs,but the participants need a fast and accurate zone temperature prediction model,e.g.,the detailed room thermal-resistance(RC)model,to improve peak shaving effect and avoid obvious thermal discomfort.However,when applying the detailed room RC model to multi-zone buildings,conventional studies mostly consider the heat transfer among neighboring rooms,which contributes little to the prediction accuracy improvement,but leads to complicated model structure and heavy computation.Thus,a distributed RC model is developed for multi-zone buildings in this study.Compared to conventional models,the proposed model considers the total heat transfer between the building and the air,and ignores the heat transfer among indoor air in neighboring rooms through internal walls with heavy thermal mass,thereby having comparable temperature prediction accuracy,simpler structure,and stronger robustness.Based on the model,the effectiveness of passive pre-cooling strategies in reducing the air conditioning loads during peak periods is investigated.Results indicate that the thermal insulation performance of opaque building envelope is quite important to the flexibility enhancement of air conditioning loads.With an uninsulated building envelope,passive pre-cooling is useless for the peak load shaving.In comparison,well insulated opaque building envelope enables the building thermal mass to be utilized through passive pre-cooling,which leads to the air conditioning loads during peak periods being further reduced by about 12%.

Global hydraulic stability analysis for dynamic regulation in multi-zone variable air volume air-conditioning system

Variable air volume air-conditioning system(VAV system)has multiple control loops that interfered with each other,which has serious impacts on its actual operation effect.To solve this problem,the index of global hydraulic stability,which takes the physical quantity of the pipe network pressure and the air flow rate as reference,is proposed based on Graph theory,and a pipe network model for the hydraulic calculation is built.Then,the simulation study based on the actual operation data is carried out in MATLAB.The distribution of the pressure and the air flow in the pipe network is obtained,and the action interferences among adjacent terminal boxes are analyzed based on global hydraulic stability under damper position regulation strategy(DP strategy)and fan frequency regulation strategy(FF strategy).Results indicate that the FF strategy can decrease the total change distance of the damper position compared with the DP strategy,and then the fluctuation of the pressure and the air flow can be reduced.The contribution of this study is to provide an evaluation index of global hydraulic stability,which can also be used in other air-conditioning systems with multiple terminals and multiple control loops.

Self-recoverable semi-crystalline hydrogels with thermomechanics and shape memory performance

Stimuli-responsive hydrogels have become one of the most popular artificial soft materials due to their excellent adaption to complex environments. Thermoresponsive hydrogels triggered by temperature change can be efficiently utilized in many applications. However, these thermoresponsive hydrogels mostly cannot recover their mechanical states under large strain during the process. Herein, we utilize the heterogeneous comb-type polymer network with semicrystalline hydrophobic side chains to design self-recovery semi-crystalline hydrogels. Based on hydrophilic/hydrophobic cooperative complementary interaction and heterogeneous polymer network, hydrogels can be endowed with excellent thermosensitive properties and mechanical performance. The hydrogels exhibit high compressive strength(7.57 MPa) and compressive modulus(1.76 MPa) due to the semi-crystalline domains formed by association of the hydrophobic poly(ε-caprolactone) PCL. The melting-crystalline transition of PCL and elastic polymer network provide the hydrogels excellent thermomechanical performance and self-recovery property. Furthermore, the hydrogels exhibit shape memory behavior, which can be realized by simple process and smart surface patterning. With these excellent properties, our hydrogels can be applied in sensors, flexible devices and scaffolds for tissue engineering.

Super-tough and strong nanocomposite fibers by flow-induced alignment of carbon nanotubes on grooved hydrogel surfaces

Nanocomposite fibers have attracted intensive attentions owing to their promising applications in various fields. However, the fabrication of nanocomposite fibers with super toughness and strong strength under mild conditions remains a great challenge. Here we present a facile flow-induced assembly strategy for the development of super-tough and strong nanocomposite fibers with highly ordered carbon nanotubes (CNTs), which can be induced by directional and fast flow on a grooved hydrogel surface. The prepared nanocomposite fibers show excellent mechanical properties, with a tensile strength up to 643±27 MPa and toughness as high as 77.3±3.4 MJ m^-3 at ultimate strain of 14.8±1.5%. This versatile and efficient flow-induced alignment strategy represents a promising direction for the development of high-performance nanocomposites for practical applications.

Anisotropic nanocomposite hydrogels with enhanced actuating performance through aligned polymer networks

Anisotropic composite hydrogels have wide applications in the fields of materials for actuators and sensors.Herein,we report an anisotropic composite hydrogel prepared by a mechanical-strain-induced method.Polymer networks including poly(N-isopropylacrylamide)(PNIPAM)and sodium alginate(SA),as well as carbon nanotubes(CNTs)are found to align simultaneously by stretching,and then fixed by physical crosslinking through non-covalent bonds.Composite hydrogels with doubly aligned polymer networks showed anisotropic optical and mechanical properties.The actuation performance of the anisotropic composite hydrogels as compared with the isotropic ones was found to be enhanced,which showed the capability of lifting 100 times its weight with 20%contraction strain.Besides,a bilayer hydrogel was designed to bend with a maximum of 390°to mimic the tendril behavior of plants.

Amphiphilic Pd@micro-organohydrogels with controlled wettability for enhancing gas-liquid-solid triphasic catalytic performance

The wettability of catalyst plays an important role in regulating catalytic performance in heterogenous catalysis because the microenvironment around the catalytic sites directly determines the mass transfer process of reactants.Inspired by gas trapped on the surface of subaquatic spiders,amphiphilic micro-organohydrogels with tunable surface wettabilities were developed by anchoring various alkane chains onto a poly(2-(dimethylamino)ethyl methacrylate)(p(DMAEMA))hydrophilic microgel network.Palladium nanoparticles(Pd NPs)were encapsulated in amphiphilic microgels(amphiphilic Pd@M)to catalyze hydrogenation reaction,achieving higher activities than pristine monohydrophilic Pd@M composite.The underwater oleophilicity and aerophilicity of Pd@M composites were quantified by oil/gas adhesion measurements and computational simulations.The higher amphiphilic catalytic activities are attributed to the formation of a gas-oil-solid reaction interface on the catalyst surfaces,allowing rapid transport of H2 and organic substrates through water to the Pd catalytic sites.Additionally,amphiphilic Pd@M composites also exhibit more superior catalytic performance in multi-substrates reaction.

A multi-functional polymer coating that is heat-resistant,hydrophobic and transparent

A multi-functional polymer film with high hydrophobicity and transparency was formed by simple casting of a polycarbonate solution onto a substrate having micro-scale roughness.The high hydrophobicity was heat-resistant,which can be retained up to 390 ℃.The polymer film may have potentially wide-ranging applications in industry and high technology.

Magnetic-programmable organohydrogels with reconfigurable network for mechanical homeostasis

Synthetic materials with tunable mechanical properties have great potential in soft robotics and biomedical engineering.However,current materials are limited to the mechanical duality altering their mechanical properties only between soft and hard states and lack of consecutively programmable mechanics.Herein,the magnetic-programmable organohydrogels with heterogeneous dynamic architecture are designed by encasing oleophilic ferrofluid droplets into hydrogel matrix.As magnetic field increases,the mechanical properties of organohydrogels can be consecutively modulated owing to the gradual formation of chain-like assembly structures of nanoparticles.The storage modulus G'increases by 2.5 times when magnetic field goes up to 0.35 T.Small-Angle X-ray Scattering(SAXS)confirms the reconfigurable orientation of nanoparticles and the organohydrogels show reversible modulus switching.Besides,the materials also exhibit high stretchability,magnetic actuation behavior and effective self-healing capability.Furthermore,the organohydrogels are applied into the design of effectors with mechanical adaptivity.When subjected to serious external perturbations,the effector can maintain mechanical homeostasis by regulating modulus of organohydrogel under applied magnetic field.Such materials are applicable to homeostatic systems with mechanically adaptive behaviors and programmed responses to external force stimuli.

Insights into reactive oxygen species formation induced by water-soluble organic compounds and transition metals using spectroscopic method

Ambient particulate matter(PM)can cause adverse health effects via their ability to produce Reactive Oxygen Species(ROS).Water-Soluble Organic Compounds(WSOCs),a complex mixture of organic compounds which usually coexist with Transition Metals(TMs)in PM,have been found to contribute to ROS formation.However,the interaction between WSOCs and TMs and its effect on ROS generation are still unknown.In this study,we examined the ROS concentrations of V,Zn,Suwannee River Fulvic Acid(SRFA),Suwannee River Humic Acid(SRHA)and the mixtures of V/Zn and SRFA/SRHA by using a cell-free 2’,7’-Dichlorodihydrofluorescein(DCFH)assay.The results showed that V or Zn synergistically promoted ROS generated by SRFA,but had an antagonistic effect on ROS generated by SRHA.Fluorescence quenching experiments indicated that V and Zn were more prone to form stable complexes with aromatic humic acid-like component(C1)and fulvic acidlike component(C3)in SRFA and SRHA.Results suggested that the underlying mechanism involving the fulvic acid-like component in SRFA more tending to complex with TMs to facilitate ROS generation throughπelectron transfer.Our work showed that the complexing ability and complexing stability of atmospheric PM organics with metals could significantly affect ROS generation.It is recommended that the research deploying multiple analytical methods to quantify the impact of PM components on public health and environment is needed in the future.

Online differential pressure reset method with adaptive adjustment algorithm for variable chilled water flow control in central air-conditioning systems

Central air-conditioning systems predominantly operate under partial load conditions.The optimization of a differential pressure setpoint in the chilled water system of a central air-conditioning system leads to a more energy-efficient operation.Determining the differential pressure adjustment value based on the terminal user's real-time demand is one of the critical issues to be addressed during the optimal control process.Furthermore,the online application of the differential pressure setpoint optimization method needs to be considered,along with the stability of the system.This paper proposes a variable differential pressure reset method with an adaptive adjustment algorithm based on the Mamdani fuzzy model.The proposed method was compared with differential pressure reset methods with reference to the chilled water differential temperature,outdoor temperature,and linear model based on the adjustment algorithm.The energy-saving potential,temperature control effect,and avoidance of the most unfavorable thermodynamic loop effects of the four methods were investigated experimentally.The results indicated that,while satisfying the terminal user's energy supply demand and ensuring the avoidance of the most unfavorable thermodynamic loop,the proposed adaptive adjustment algorithm also decreased the differential pressure setpoint value by 25.1%—59.1%and achieved energy savings of 10.6%-45.0%.By monitoring the valve position and supply air temperature of each terminal user,the proposed method exhibited suitable online adaptability and could be flexibly applied to buildings with random load changes.

Clinical correlations with disease-associated auto-antibodies in a Chinese cohort with systemic sclerosis

To the Editor:Systemic sclerosis(SSc)is an autoimmune disease characterized by,progressive skin and visceral fibrosis,microvasculopathy,and autoimmunity.Circulating auto-antibodies(AAbs)are detectable in 90%to 95%of patients with SSc.