ADCP测流在巢湖流域水资源监测中的应用

为满足巢湖湖(河)长制考核验收的需要,需对巢湖43个考核断面建设水资源监测站,对ADCP测流技术,以及走航式、水平式和垂线式3种测流设备进行介绍和比较,根据各种测流设备的适用范围和测流断面的特征,选择合适的建设方案,方案实施后,可以实现水质和水量同步监测,控制河流入湖污染总量,为湖(河)长制考核验收提供数据支持。     

Modulation of Alkyl Chain Length on the Thiazole Side Group Enables Over 17% Efficiency in All-Small-Molecule Organic Solar Cells

Molecular innovation is highly desirable to achieve efficient all-small-molecule organic solar cells (SM-OSCs). Herein, three small-molecule donors (SMDs) with alkylated thiazole side groups (namely BO-1, HD-1, and OD-1), which differ only in the alkyl side chain are reported. Although these SMDs possess similar absorption profiles and molecular energy levels, their crystallinity and miscibility with BTP-eC9 slightly decrease along with the elongation of the alkyl side chain. After blending with BTP-eC9, different miscibility leads to different degrees of phase separation. Among these SM-OSCs, the HD-1-based device shows a decent bulk-heterojunction (BHJ) morphology with proper phase separation and more dynamic carrier behavior. Thus, compared to the BO-1 and OD-1-based devices, the HD-1-based device achieves a higher short-circuit current of 26.04 mA cm⁻² and a fill factor of 78.46%, leading to an outstanding PCE of 17.19%, which is one of the highest values among SM-OSCs. This work provides a rational design strategy of SMDs for highly efficient SM-OSCs.     

Unlocking dynamics of compact methanol reformers during on-line catalyst activation using transient computational fluid dynamics simulation

On-board methanol reforming is a practical solution to supply hydrogen for fuel cell vehicles (FCVs). For commonly employed Cu-based reforming catalysts, activation has a profound influence on subsequent reaction performance. However, tailoring of this process at the reformer level has received little research attention. Herein, we present the dynamics of compact methanol reformers with Cu/ZnO/Al₂O₃ catalysts during in situ H₂/N₂ pre-activation as a preliminary step of online catalyst activation by computational fluid dynamics simulations. Raising inlet temperatures or hydrogen fractions is demonstrated to accelerate activation while generating a high-temperature band within the catalyst bed, which hampers effective activation. Increasing the reductant flow rates improves the homogeneity of activation thanks to enhanced convective heat and mass transfer. Notably, we revealed that inlet reductants exceeding 453 K trigger temperature runaway that may severely damage the reformer. These new insights will enlighten optimization of operation and control of on-board methanol reforming for FCVs.     

蓝靛果汁加工过程中褐变机理及防控技术

目的:探究蓝靛果汁在加工过程中的褐变反应机理。方法:测定蓝靛果汁在杀菌过程中褐变度、维生素C(V_C)含量、5-羟甲基糠醛(5-HMF)含量的变化，并进行动力学模型拟合；优化蓝靛果汁褐变抑制工艺条件，并测定优化后蓝靛果汁在4,25,37℃下贮藏30 d过程中微生物、理化、感官指标的变化。结果:褐变度、V_C含量、5-HMF含量变化分别符合联合、一级、零级反应动力学模型。最优褐变抑制工艺条件为葡萄糖氧化酶添加量0.21%、作用温度39℃、作用时间45 min,此条件下果汁非酶褐变抑制率为95.13%。蓝靛果汁在4℃下测试指标变化相对迟缓，贮藏末期，其菌落总数<100 CFU/mL,可溶性固形物、总酚、花色苷、V_C、还原糖含量相对较高，分别为14.15%、262.02 g/100 g、380.50 mg/L、65.37 mg/L、9.62 g/100 g,感官评分为82.3分，具有蓝靛果的果香与果味、颜色均一、质地均匀。结论:试验方法显著抑制了蓝靛果汁在贮藏期间的褐变。     

Preparation of SiCf/Si–O–C composites by impregnation pyrolysis of polysiloxane and its electromagnetic wave absorption properties

High-temperature structural electromagnetic wave (EMW) absorption materials are increasing in demand because they can simultaneously possess the functions of mechanical load-bearing, heatproof, and EMW absorption. Herein, SiC_f/Si–O–C composites were prepared by precursor impregnation pyrolysis using continuous SiC fibers needled felt as reinforcement and polysiloxane as a precursor, respectively. The phase composition, microstructure, complex permittivity, and EMW absorption properties of SiC_f/Si–O–C composites after annealing at various temperatures were investigated. The annealing at 1400–1500°C affects positively the EMW absorption performance of the composites, because the β-SiC microcrystals and SiC nanowires were generated by the activation of carbothermal reduction reaction in the composites, and the aspect ratio of SiC nanowires increased with the rise of temperature. The composites exhibit optimal EMW absorption performance, with the effective absorption bandwidth covering the entire X-band and the minimum reflection loss (RL_min) of −32.8 dB at 4.0 mm when the annealing temperature is raised to 1500°C. This is because that the impedance matching is improved as the rising of ε′ and decreasing of ε″ due to the conversion of free carbon in the composite into SiC nanowires.     

Atomic Optimization on Pyran-Fused Nonfullerene Acceptor Enables Organic Solar Cells With an Efficiency Approaching 16% and Reduced Energy Loss

Atomic replacement on platforms of nonfullerene acceptor (NFA) with already excellent performance is expected to further optimize the energy levels, absorptions, and even charge transfer dynamics of NFAs effectively without greatly destroying their superior molecular conformations. On the basis of high-performance F-series NFAs, the structural optimization at atomic level is performed by replacing sulfur atoms in FO-2Cl with selenium atoms, thus affording a new NFA labeled as FOSe-2Cl. FOSe-2Cl not only inherits the good planar configuration of FO-2Cl, but also exhibits more suitable energy levels, redshifted absorption, enhanced molecular packing, and accelerative charge transfer/transport dynamics compared with those of FO-2Cl. With a widely used polymer PM6 as the donor, organic solar cell (OSC) based on FOSe-2Cl affords a significantly improved power conversion efficiency (PCE) of 15.94% with a reduced energy loss (E_loss) of 0.670 eV, with respect to that of FO-2Cl-based OSC with a PCE of 14.94% and E_loss of 0.706 eV. The result represents the best performance reported to date for pyran-fused NFAs and F-series NFAs-based binary OSCs, providing another promising platform to achieve the state-of-the-art OSCs in addition to the well-known Y-series NFAs.     

聚对苯乙烯磺酸微球的绿色制备及催化合成生物柴油

以水为介质、苯乙烯（St）为基体单体、二乙烯苯（DVB）为交联单体、对苯乙烯磺酸钠（Na SS）为功能单体、甲基丙烯酸（MAA）为水溶性单体、过硫酸钾（KPS）为引发剂，采用无皂乳液聚合法制备了聚对苯乙烯磺酸微球（PSS）。利用FTIR、XPS、SEM、TGA和DSC对其进行了表征，并对其粒径、Zeta电位、比表面积、酸密度进行了考察，探讨了Na SS、DVB和KPS用量对PSS结构、性能的影响。当H2O为90m L、St为76.9 mmol、MAA为9.3 mmol、NaSS为0.7mmol、DVB为7.7 mmol、KPS为0.7mmol时，制备的PSS-3粒径均匀且酸密度较高。然后，将PSS-3作为固体酸催化剂，用于催化油酸/甲醇酯化合成生物柴油（油酸甲酯）。结果表明，当甲醇/油酸的物质的量比为10∶1、PSS-3用量为油酸质量的2%、反应温度为80℃、反应时间为6h时，油酸的转化率可达86.4%。PSS-3作为固体酸催化剂具有较好的重复使用性能，循环使用4次后油酸转化率没有明显下降。     

Probing the Mysterious Behavior of Tungsten as a Dopant Inside Pristine Cobalt-Free Nickel-Rich Cathode Materials

Nickel-rich cathode materials with small amounts of tungsten (W) dopants have attracted extensive attention in recent years. However, the chemical state, crystalline form, compound chemistry, and location of W in these layered cathodes are still not well-understood. In this study, these missing structural properties are determined through a combination of macro-, to atomic-sensitive characterization techniques and density functional theory (DFT). W-doped LiNiO₂ (LNO) particles, prepared with mechanofusion and coprecipitation methods, are used to probe changes in the structure and location of W-species. The results indicate that W is mainly distributed on the surfaces and inside grain boundaries of the secondary particles, regardless of the doping method. Electron energy loss spectroscopy (EELS) mapping confirms the simultaneous presence of W, O, with and without Ni in the grain boundaries as well as W- and O-rich regions on the very surface. The W-rich areas inside the grain boundaries are found to be in two forms, crystalline and amorphous. This paper suggests the presence of kinetically stabilized-Li_4+xNi_1-xWO₆ (x = 0, 0.1) with the possibility of Li_xW_yO_z phases in LNO which are consistent with the electron microscopy, X-ray absorption and diffraction data. The multiple roles of W in this complex microstructure are discussed considering the W distribution.     

Deformation Rate-Adaptive Conducting Polymers and Composites

Materials are more easily damaged during accidents that involve rapid deformation. Here, a design strategy is described for electronic materials comprised of conducting polymers that defies this orthodox property, making their extensibility and toughness dynamically adaptive to deformation rates. This counterintuitive property is achieved through a morphology of interconnected nanoscopic core–shell micelles, where the chemical interactions are stronger within the shells than the cores. As a result, the interlinked shells retain material integrity under strain, while the rate of dissociation of the cores controls the extent of micelle elongation, which is a process that adapts to deformation rates. A prototype based on polyaniline shows a 7.5-fold increase in ultimate elongation and a 163-fold increase in toughness when deformed at increasing rates from 2.5 to 10 000% min⁻¹. This concept can be generalized to other conducting polymers and highly conductive composites to create “self-protective” soft electronic materials with enhanced durability under dynamic movement or deformation.