Templated synthesis and assembly with sustainable cellulose nanomaterial for functional nanostructure

Cellulose - Templated synthesis and assembly for nanostructured materials with tailored properties have received considerable attention. The powerful templates with predefined structures can guide...     

The First One‐Pot Synthesis of Metal–Organic Frameworks Functionalised with Two Transition‐Metal Complexes

The synthesis of a metal–organic framework (UiO‐67) functionalised simultaneously with two different transition metal complexes (Ir and Pd or Rh) through a one‐pot procedure is reported for the first time. This has been achieved by an iterative modification of the synthesis parameters combined with characterisation of the resulting materials using different techniques, including X‐ray absorption spectroscopy (XAS). The method also allows the first synthesis of UiO‐67 with a very wide range of loadings (from 4 to 43 mol %) of an iridium complex ([IrCp*(bpydc)(Cl)Cl]^2?; bpydc=2,2′‐bipyridine‐5,5′‐dicarboxylate, Cp*=pentamethylcyclopentadienyl) through a pre‐functionalisation methodology.     

Determination of five sesquiterpenoids in Xingnaojing injection by quantitative analysis of multiple components with a single marker

A quantitative analysis of multiple components with a single‐marker method was established for the simultaneous determination of five sesqutiterpenoids in Xingnaojing injection. This method was established with Xingnaojing injection determined by high‐performance liquid chromatography coupled with diode array detection. The durability and system suitability of the established method were evaluated, and the reliable relative correction factors were obtained with curdione selected as an internal reference. The contents of the five components in all Xingnaojing injections were determined by external standard method and the contents of curcumenone, curcumenol, curzerenone, and germacrone were also calculated with the obtained relative correction factors. Then, relative error was investigated to estimate the difference of the two methods. As a result, the established new method possesses good adaptability, and there is no significant difference between the two methods, except for the content of curzerenone in eight samples. To put the established method into practice, the limits of quantitation of the established method of the five components were proposed and defined. Thus, the developed methodology can also be utilized to the quality evaluation of Xingnaojing injection, in spite of the difference found in the content of curzerenone between the external standard method and the newly established method.     

Numerical Investigation on 1,3-Butadiene/Propyne Co-pyrolysis and Insight into Synergistic Effect on Aromatic Hydrocarbon Formation

A numerical investigation on the co-pyrolysis of 1,3-butadiene and propyne is performed to explore the synergistic effect between fuel components on aromatic hydrocarbon formation.A detailed kinetic model of 1,3-butadiene/propyne co-pyrolysis with the sub-mechanism of aromatic hydrocarbon formation is developed and validated on previous 1,3-butadiene and propyne pyrolysis experiments.The model is able to reproduce both the single component pyrolysis and the co-pyrolysis experiments,as well as the synergistic effect between 1,3-butadiene and propyne on the formation of a series of aromatic hydrocarbons.Based on the rate of production and sensitivity analyses,key reaction pathways in the fuel decomposition and aromatic hydrocarbon formation processes are revealed and insight into the synergistic effect on aromatic hydrocarbon formation is also achieved.The synergistic effect results from the interaction between 1,3-butadiene and propyne.The easily happened chain initiation in the 1,3-butadiene decomposition provides an abundant radical pool for propyne to undergo the H-atom abstraction and produce propargyl radical which plays key roles in the formation of aromatic hydrocarbons.Besides,the 1,3-butadiene/propyne co-pyrolysis includes high concentration levels of C3 and C4 precursors simultaneously,which stimulates the formation of key aromatic hydrocarbons such as toluene and naphthalene.     

Preparation and thermal reliability of <Emphasis Type="Italic">N</Emphasis>-butyl stearate/methyl palmitate composite phase change material

In this study, a series of binary mixtures of N-butyl stearate (nBS) and methyl palmitate (MP) were used to produce a novel composite phase change material (CPCM) for potential application in the eastern China, and their thermal properties were investigated by differential scanning calorimetry (DSC). The results of DSC indicated that the mixture consisting of 10 mass% nBS and 90 mass% MP is optimum as the CPCM in terms of the phase change temperature ranges (T _f = 19.74–5.59 °C; T _m = 18.34–33.80 °C) and latent heats (ΔH _f = 176.8 J g^?1; ΔH _m = 189.3 J g^?1). On the other hand, the thermal reliability and chemical stability of the CPCM after 120, 180, 240, 300, 360 and 500 accelerated thermal cycling tests were studied by DSC and fourier transform infrared (FTIR) analysis. The results demonstrated that the CPCM had good thermal reliability and chemical stability.     

Exact separation theorem for closed sets in Asplund spaces

In this paper, in terms of the Fréchet normal cone, we establish exact separation results for finitely many disjoint closed sets in an Asplund space, which supplement the extremal principle and some fuzzy separation theorems. As an application, we provide a new optimality condition for a constraint optimization problem in terms of Fréchet subdifferential and Fréchet normal cone.     

北京市PM2.5的相关因素研究

选取2016年北京市空气质量指数数据,简述了北京市空气的现状,并根据频率得出PM2.5已经成为北京市空气中的首要污染物的结论.通过计算PM2.5与AQI所监测的其余指标之间的相关程度,进行PM2.5与PM10,CO和NO2的多元回归分析,得到线性回归方程.同时对模型给予改进,建立基于2个主成分的、更为精准的多元回归模型.得出PM10是空气中PM2.5的最主要成因的结论,CO和NO2对PM2.5的影响也不容忽视的结论,对北京市雾霾天气预防提供参考意见.     

Rich-defect carbon nanotubes for highly sensitive detection of Dopamine

Dopamine (DA) plays an essential role in the central nervous, renal, hormonal and cardiovascular systems. Various modified carbon nanotubes (CNT)-based dopamine sensors have been reported, but inexpensive, highly sensitive plain CNT-based ones are seldom studied. In this work, a facile and inexpensive CNT-based DA sensor is made by rich-defect multi-walled carbon nanotubes (RD-CNT) via an ultrasound method. The defect and elemental states of the RD-CNT are systematically studied by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), Raman spectroscopy, X-ray powder diffraction (XRD) and X-ray-photoelectron spectroscopy (XPS). Results show that massive holes and cracks exist in RD-CNT. The level of defects increases from the additional exposed edges. The electrochemical characterizations indicate that the electrochemical sensor has the highest sensitivity of 438.4 μA/(μM ⋅ cm²) among all carbon materials-based DA sensors while well meeting the clinically required detection range and selectivity. The DA sensor was further used to detect live healthy human serum and live PC12 cells with satisfactory results, thus holding great promise for an inexpensive but sensitive DA sensor in practical applications of clinical diagnosis and biological research.     

Electronic Perturbation of Copper Single-Atom CO2 Reduction Catalysts in a Molecular Way

Fine-tuning electronic structures of single-atom catalysts (SACs) plays a crucial role in harnessing their catalytic activities, yet challenges remain at a molecular scale in a controlled fashion. By tailoring the structure of graphdiyne (GDY) with electron-withdrawing/-donating groups, we show herein the electronic perturbation of Cu single-atom CO₂ reduction catalysts in a molecular way. The elaborately introduced functional groups (−F, −H and −OMe) can regulate the valance state of Cu^δ+, which is found to be directly scaled with the selectivity of the electrochemical CO₂-to-CH₄ conversion. An optimum CH₄ Faradaic efficiency of 72.3 % was achieved over the Cu SAC on the F-substituted GDY. In situ spectroscopic studies and theoretical calculations revealed that the positive Cu^δ+ centers adjusted by the electron-withdrawing group decrease the pK_a of adsorbed H₂O, promoting the hydrogenation of intermediates toward the CH₄ production. Our strategy paves the way for precise electronic perturbation of SACs toward efficient electrocatalysis.