氨蒸发诱导法制备纳米结构LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2及其作为高功率型锂离子电池正极材料的性能

采用氨蒸发诱导法成功制备出纳米结构LiNi1/3Co1/3Mn1/3O2正极材料,借助X射线衍射(XRD)分析、扫描电镜(SEM)、透射电镜(TEM)、高分辨率透射电镜(HRTEM)、能量分散谱(EDS)和比表面测试等表征手段及恒电流充放电测试研究了其晶体结构、微观形貌和电化学性能.研究表明该方法制备出的材料具有良好的α-NaFeO2层状结构,阳离子混排程度低.纳米片交错堆积而成核桃仁状形貌,片与片之间形成许多纳米孔,而且纳米片的侧面属于{010}活性面,能够提供较多的锂离子的脱嵌通道.在室温下及3.0-4.6 V充放电范围内,该材料在电流密度为0.5C、1C、3C、5C和10C时放电比容量分别为172.90、153.95、147.09、142.16和131.23mAh?g-1.说明其具有优异的电化学性能,非常有潜力用于动力汽车等高功率密度锂离子电池中.     

Capillary electrophoresis with laser-induced fluorescence detection of main polyamines and precursor amino acids in saliva

A hollow-fiber liquid-phase microextraction （HF-LPME） method has been developed for the purification and preconcentration of biogenic polyamines and their precursor amino acids in human saliva. Putrescine （Put）, cadaverine （Cad）, spermidine （Spe）, ornithine （Orn）, lysine （Lys）, and arginine （Arg） were determined by the CE-LIF detection after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, six analytes could achieve baseline separation within 30 min, exhibiting a linear calibration at three orders of magnitude （r2 〉 0.998）; the obtained enrichment factors of HF-LPME were between 19 （for Orn） and 2] 8 （for Cad）, and the LODs were in the range of 0.0072-0.26 nmol/L. The proposed HF-LPME/CE-LIF method has been successfully applied for the sensitive analyses of the real-world saliva samples collected from healthy volunteers and different patients with oral diseases, providing a potential method for primary non-invasive diagnosis of some oral diseases.     

Complexation of 1,3-Diamino-2-hydroxypropane- N,N , N ', N '-tetraacetic Acid (DHPTA) with Heavy Lanthanides (Tb 3+ , Ho 3+ , Lu 3+ ) in Aqueous Solution

Thermodynamic equilibria of complexes of 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (DHPTA) with heavy lanthanides (Tb3+, Ho3+ and Lu3+) in aqueous solution have been investigated with potentiometry, spectrophotometry, luminescence spectroscopy and nuclear magnetic resonance spectroscopy (NMR). The results identified three 1:1 Ln/DHPTA (Ln: Tb3+, Ho3+ and Lu3+) complexes with different degrees of deprotonation, LnL−, Ln(H−1L)2−, and Ln(OH)(H−1L)3−, where H−1 represents the deprotonation of the hydroxyl group between two methyliminodiacetate groups in the DHPTA structure. The alkoxide form of the DHPTA hydroxyl group directly binds to the lanthanide atom, forming highly strong chelation. The complex of Ln(H−1L)2− could be present as a dimeric or polymeric complex in solution.     

基于正电荷和光热协同效应的新型半导体聚合物纳米抗菌材料

由于抗生素的不当使用和细菌多药耐药的出现, 迫切需要开发新的抗菌剂. 本文制备了具有光热转换性能的正电荷半导体高分子材料及具有协同抗菌活性的半导体聚合物纳米粒子(SP-PPh₃ NPs). SP-PPh₃ NPs的光热转化效率为43.8%. 带正电荷的SP-PPh₃ NPs可以附着在细菌上, 有助于将热量有效传递给细菌. 在热和正电荷的协同作用下, SP-PPh₃ NPs对革兰氏阴性大肠杆菌(E. coli)和革兰氏阳性金黄色葡萄球菌(S. aureus)均具有抗菌活性, 其对二者的体外抑菌率分别为99.9%和98.6%. 此外, SP-PPh₃ NPs具有良好的生物相容性, 对小鼠的主要器官几乎无副作用. 对细菌感染的小鼠皮肤伤口用SP-PPh₃ NPs治疗12 d后, 伤口可以很好地愈合.     

Photoinduced Single‐Electron Transfer as an Enabling Principle in the Radical Borylation of Alkenes with NHC–Borane

A photoinduced SET process enables the direct B?H bond activation of NHC–boranes. In contrast to common hydrogen atom transfer (HAT) strategies, this photoinduced reaction simply takes advantage of the beneficial redox potentials of NHC–boranes, thus obviating the need for extra radical initiators. The resulting NHC–boryl radical was used for the borylation of a wide range of α‐trifluoromethylalkenes and alkenes with diverse electronic and structural features, providing facile access to highly functionalized borylated molecules. Labeling and photoquenching experiments provide insight into the mechanism of this photoinduced SET pathway.     

Photo‐excited Oxygen Reduction and Oxygen Evolution Reactions Enable a High‐Performance Zn–Air Battery

The storage of solar energy in battery systems is pivotal for a sustainable society, which faces many challenges. Herein, a Zn–air battery is constructed with two cathodes of poly(1,4‐di(2‐thienyl))benzene (PDTB) and TiO₂ grown on carbon papers to sandwich a Zn anode. The PDTB cathode is illuminated in a discharging process, in which photoelectrons are excited into the conduction band of PDTB to promote oxygen reduction reaction (ORR) and raise the output voltage. In a reverse process, holes in the valence band of the illuminated TiO₂ cathode are driven for the oxygen evolution reaction (OER) by an applied voltage. A record‐high discharge voltage of 1.90 V and an unprecedented low charge voltage of 0.59 V are achieved in the photo‐involved Zn–air battery, regardless of the equilibrium voltage. This work offers an innovative pathway for photo‐energy utilization in rechargeable batteries.     

Dual‐Mode Antibacterial Conjugated Polymer Nanoparticles for Photothermal and Photodynamic Therapy

In this work, dual‐mode antibacterial conjugated polymer nanoparticles (DMCPNs) combined with photothermal therapy (PTT) and photodynamic therapy (PDT) are designed and explored for efficient killing of ampicillin‐resistant Escherichia coli (Amp^r E. coli). The DMCPNs are self‐assembled into nanoparticles with a size of 50.4 ± 0.6 nm by co‐precipitation method using the photothermal agent poly(diketopyrrolopyrrole‐thienothiophene) (PDPPTT) and the photosensitizer poly[2‐methoxy‐5‐((2‐ethylhexyl)oxy)‐p‐phenylenevinylene] (MEH‐PPV) in the presence of poly(styrene‐co‐maleic anhydride) which makes nanoparticles disperse well in water via hydrophobic interactions. Thus, DMCPNs simultaneously possess photothermal effect and the ability of sensitizing oxygen in the surrounding to generate reactive oxygen species upon the illumination of light, which could easily damage resistant bacteria. Under combined irradiation of near‐infrared light (550 mW cm^?2, 5 min) and white light (65 mW cm^?2, 5 min), DMCPNs with a concentration of 9.6 × 10^?4 µm could reach a 93% inhibition rate against Amp^r E. coli, which is higher than the efficiency treated by PTT or PDT alone. The dual‐mode nanoparticles provide potential for treating pathogenic infections induced by resistant microorganisms in clinic.     

Zinc–Organic Battery with a Wide Operation‐Temperature Window from −70 to 150 °C

Aqueous zinc (Zn) batteries have been considered as promising candidates for grid‐scale energy storage. However, their cycle stability is generally limited by the structure collapse of cathode materials and dendrite formation coupled with undesired hydrogen evolution on the Zn anode. Herein we propose a zinc–organic battery with a phenanthrenequinone macrocyclic trimer (PQ‐MCT) cathode, a zinc‐foil anode, and a non‐aqueous electrolyte of a N,N‐dimethylformamide (DMF) solution containing Zn²⁺. The non‐aqueous nature of the system and the formation of a Zn²⁺–DMF complex can efficiently eliminate undesired hydrogen evolution and dendrite growth on the Zn anode, respectively. Furthermore, the organic cathode can store Zn²⁺ ions through a reversible coordination reaction with fast kinetics. Therefore, this battery can be cycled 20 000 times with negligible capacity fading. Surprisingly, this battery can even be operated in a wide temperature range from ?70 to 150 °C.     

碳纤维复合材料冲击模型率相关修正方法与试验研究

目前先进航空发动机的风扇叶片均采用复合材料结构,为了研究其在工作过程中可能受到的冲击损伤,即碳纤维增强树脂基复合材料受到高速冲击后的损伤与破坏过程,对其准静态下的正交各向异性本构模型和失效准则进行修正,建立了应变率相关的三维动态本构及损伤模型．该模型考虑了材料模量、强度和断裂韧性与应变率的相关性,并采用基于断裂韧性的渐进损伤模式对刚度进行折减来控制破坏过程．开展了不同应变率下的动态试验,得到基体方向拉伸与剪切的动态响应数据,拟合得到相应的动态修正因子．将该模型结合修正因子植入数值软件进行仿真计算,分析结果表明,所建立的率相关本构及损伤模型能够更准确地模拟层合板受冲击过程的损伤和破坏,与试验吻合较好．