Effect of high-temperature crystallization on the electrochemical properties of LiNi<Subscript>0.5</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.3</Subscript>O<Subscript>2</Subscript> synthesized from a lithiated transition metal oxide precursor

The lithiated transition metal oxide precursor (LNCMO) with typical α-NaFeO₂ structure and imperfect crystallinity, obtained from a hydrothermal process, was pretreated at 500 °C and then subjected to sintering at 800–920 °C to synthesize the ternary layered LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523). X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge testing were used for investigating the effect of the high-temperature crystallization on the properties of the NCM523 cathode materials. The results show that the materials heated at 880–900 °C possess superior cation ordering, perfect crystallinity, and excellent electrochemical performances, among which the material heated at 900 °C delivers better performances, with the initial discharge capacity of 152.6 mAh g^?1 at 0.5 C over 3.0 to 4.3 V and the capacity retention of 95.5% after 50 cycles. Furthermore, the effect of the high-temperature crystallization on the Li⁺ diffusion coefficient, potential polarization, and electrochemical resistance are discussed.     

Sensing and fluorescence behaviors of complex formation between new lariat crown ethers bearing fluorescence sidearm and metal ions in methanol solution

Fluorescence spectroscopic properties of the complex formation between six new C-pivot16-crown-5 ethers bearing fluorescence side arms and metal ions are studied. Six new C-pivot 16-crown-5 ethers that carry fluorescence side arms were synthesized. The research also included the examination of different fluorescent behavior of the new lariat ethers in the presence of silver and sodium ions (Ag⁺ and Na⁺) in methanol. Because of the good fit of the cavity size of these 16-crown-5 ethers with the Ag⁺ and Na⁺ ions, remarkable change in fluorescent spectra were observed. The results showed that the new lariat crown ethers exhibited enhanced selectivity towards sodium ion, but silver ion show quenching abilities towards the ligands. Cooperative participations of the C-pivot side arm oxygen with the ring oxygen molecules in complexation was also confirmed by the single crystal X-ray crystallography of the complex, (C₂₇H₃₀O₇)·NaClO₄. The freezing of crown ring conformation and the diminishment of the chance of sidearm oscillation that occurred upon complexation with sodium ion are the main causes of fluorescent enhancement. The quenching caused by the addition of silver ion was found to explainable by the photo-induced electron transfer that results in the reduction of silver ions.     

蚜虫胁迫下棉叶光谱特征及其遥感估测

在棉蚜危害棉花的主要生育期测试蚜害后不同严重度叶片的理化参数和光谱,分析并比较了不同时期、不同品种蚜害棉叶理化参数和光谱反射率特征,确定了蚜害棉叶光谱敏感波段,建立了蚜害棉叶严重度估测模型。结果表明:蚜害棉叶的理化参数和光谱特征明显,蚜害棉叶平均厚度,含水量,温度和叶片CHL.b均增加,叶片而平均CHL.a,CHL.a+b和Cars含量减少。不同时期、不同品种蚜害棉叶光谱反射率在可见光均表现先升后降的特征,但不同品种蚜害棉叶在近红外波段反射率不同。434～727和648nm可分别作为蚜害棉叶的光谱敏感波段和最佳波段。基于敏感波段建立的蚜害棉叶遥感估测模型均达到显著相关,其中以(R1589-R648)/(R1589+R648)为自变量建立的估算模型精度最高,相对误差最小(0.128),可作为蚜害棉叶严重度最佳识别模型。该研究为遥感大面积监测棉花蚜虫提供了理论依据及参考。     

Fabrication of polymer compound microlens by lens-on-lens microstructures

We proposed a novel method for fabricating polymer compound microlenses (PCMLs) using micro-inkjet technique and subsequent curing process. Two different types of PCMLs with sandwich microstructure (PDMS-Glycerol-PDMS), concave and convex PCMLs, have been designed and fabricated in experiments. Convex PCML has two real images and two foci. The concave PCML has one real and one virtual focal planes, which can generate one real image and one virtual image respectively. Moreover, the diameter of concave PCML can be controlled by adjusting the curing time and temperature. The proposed method is simple, efficient and suitable for realizing large-scale high numerical aperture PCMLs array, which has potential applications in diverse optical systems such as optical storage and three-dimensional imaging.     

One-step hydrothermal synthesis of feather duster-like NiS@MoS<Subscript>2</Subscript> with hierarchical array structure for the Pt-free dye-sensitized solar cell

Novel feather duster-like nickel sulfide (NiS) @ molybdenum sulfide (MoS₂) with hierarchical array structure is synthesized via a simple one-step hydrothermal method, in which a major structure of rod-like NiS in the center and a secondary structure of MoS₂ nanosheets with a thickness of about 15–55 nm on the surface. The feather duster-like NiS@MoS₂ is employed as the counter electrode (CE) material for the dye-sensitized solar cell (DSSC), which exhibits superior electrocatalytic activity due to its feather duster-like hierarchical array structure can not only support the fast electron transfer and electrolyte diffusion channels, but also can provide high specific surface area (238.19 m² g^?1) with abundant active catalytic sites and large electron injection efficiency from CE to electrolyte. The DSSC based on the NiS@MoS₂ CE achieves a competitive photoelectric conversion efficiency of 8.58%, which is higher than that of the NiS (7.13%), MoS₂ (7.33%), and Pt (8.16%) CEs under the same conditions.

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Graphical abstract Novel feather duster-like NiS@MoS₂ hierarchical structure array with superior electrocatalytic activity was fabricated by a simple one-step hydrothermal method.

     

A Study on Photoacoustic Phase Spectra of Rare Earth Complexes with Oxine

Photoacoustic phase is the time delay that occurs from light to acoustic signal. the phase includes two components: one is the time delay that occurs during the process in which light absorbed by a sample converts into heat; the other is the time delay caused from heat to acoustic signal. a modified formula of PA phase is presented based on the R-G theory considering the phase caused by non-radiative relaxation processes. the phase is associated with absorption coefficient (β), thermal diffusion length of sample (μ_s), the longest lifetime of all excited states (r), and the ratio of rapid to slow heat component (R). When the photoacoustic signal is saturated the phase is associated with only T and R. the effect of different rare earth ions on the PA phase spectra of the ligand (oxine) in the rare earth complexes are reported and are well explained by using the phase formula of PA saturation.     

优化几何构型对高级别从头算能量的影响

对《ＣＲＣ物理与化学手册》（第７７版）中第三周期以前的无机双原子分子,当其理论优化构型的相对误差大于２％时,分别在实验构型和最大偏差的理论构型下,计算了ＱＣＩＳＤ（Ｔ）／６－３１１＋Ｇ（３ｄｆ,２ｐ）能量并作了比较。结果表明,大多数能量的差别在４．２ｋＪ．ｍｏｌ＾－１以内。由此说明,目前一般采用的构型优化理论方法,多数情况下不至于明显影响单点高级别从头算的计算精度。同时还发现,Ｇ２（ＱＣＩ）的高级     

关于中心原子杂化轨道数的计算方法

对于HmABn型的共价分子（或离子）,本文提出用公式G=V／2-3n计算中心原子A的杂化轨道数,并由此确定对应的杂化轨道类型。该方法简单、直接、有效。     

4-氨基丁醇的高效合成方法

以2, 3-二氢呋喃为原料,先用酸性水溶液处理,得到的粗品再直接与盐酸羟胺发生反应,得到4-羟基丁基肟,再与还原试剂发生还原反应,最终高效得到4-氨基丁醇产品。此合成方法步骤短且易操作,产率高,可用于大量生产。