Dispersion of T1 and T2 Nuclear Magnetic Resonance Relaxation in Crude Oils

Crude oils, which are complex mixtures of hydrocarbons, can be characterized by nuclear magnetic resonace diffusion and relaxation methods to yield physical properties and chemical compositions. In particular, the field dependence, or dispersion, of T₁ relaxation can be used to investigate the presence and dynamics of asphaltenes, the large molecules primarily responsible for the high viscosity in heavy crudes. However, the T₂ relaxation dispersion of crude oils, which provides additional insight when measured alongside T₁, has yet to be investigated systematically. Here we present the field dependence of T₁‐T₂ correlations of several crude oils with disparate densities. While asphaltene and resin‐containing crude oils exhibit significant T₁ dispersion, minimal T₂ dispersion is seen in all oils. This contrasting behavior between T₁ and T₂ cannot result from random molecular motions, and thus, we attribute our dispersion results to highly correlated molecular dynamics in asphaltene‐containing crude oils.     

Blue Luminescence of Dendrimer‐Encapsulated Gold Nanoclusters

Direct evidence for the blue luminescence of gold nanoclusters encapsulated inside hydroxyl‐terminated polyamidoamine (PAMAM) dendrimers was provided by spectroscopic studies as well as by theoretical calculations. Steady‐state and time‐resolved spectroscopic studies showed that the luminescence of the gold nanoclusters consisted largely of two electronic transitions. Theoretical calculations indicate that the two transitions are attributed to the different sizes of the gold nanoclusters (Au₈ and Au₁₃). The luminescence of the gold nanoclusters was clearly distinguished from that of the dendrimers.     

Preparation of stable gold nanoparticles by using diblock copolymer mixture as encapsulating agent

Gold nanoparticles by using the mixture of polystyrene-block-poly(2-vinyl pyridine)/poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PS-b-P2VP/P2VP-b-PEO) block copolymers as encapsulating agent was prepared. The prepared nanoparticles were characterized by transmission electron microscopy, UV-Vis spectroscopy and contact angle. It is demonstrated that the obtained gold nanoparticles are covered with mixed block copolymer shells. The hydrophilic property of the nanoparticles can be varied by the change of the dispersion medium. The obtained gold nanoparticles with mixed block copolymer shells are stable in organic solvents (such as tetrahydrofuran and toluene) and water.     

Peptide prefractionation is essential for proteomic approaches employing multiple‐reaction monitoring of fruit proteomic research

Off‐gel? IEF has become a popular tool in proteomics research to fractionate peptides or proteins. We conducted a detailed investigation on the fruit proteomics of apple, banana, and strawberry fruit employing Off‐gel? electrophoresis (OGE) as a crucial step to improve the proteome coverage and quantitative proteomic workflows including multiple‐reaction monitoring (MRM). We provide technical details concerning the application of Off‐gel?IEF, nano‐LC–MS detection, and MRM optimization and analysis. Our results demonstrated that the application of OGE is an effective method for peptide fractionation and increased significantly the number of proteins identified by at least ten times, with more total peptides detected and collected. Furthermore, we developed a protocol combining OGE and MRM studies to identify and quantitatively investigate monodehydroascorbate reductase, a key enzyme in the redox and antioxidant system of apple fruit during fruit ripening. Using this method, the quantitative changes in this protein during ripening and in response to ethylene treatment was investigated. Our results provide direct and comprehensive evidence demonstrating the benefits of OGE and its application for both shotgun and quantitative proteomics research.     

High‐expression β1 adrenergic receptor/cell membrane chromatography method based on a target receptor to screen active ingredients from traditional Chinese medicines

β‐Adrenergic receptors are important targets for drug discovery. We have developed a new β₁‐adrenergic receptor cell membrane chromatography (β₁AR‐CMC) with offline ultra‐performance LC (UPLC) and MS method for screening active ingredients from traditional Chinese medicines. In this study, Chinese hamster ovary‐S cells with high β₁AR expression levels were established and used to prepare a cell membrane stationary phase in a β₁AR‐CMC model. The retention fractions were separated and identified by the UPLC–MS system. The screening results found that isoimperatorin from Rhizoma et Radix Notopterygii was the targeted component that could act on β₁AR in similar manner of metoprolol as a control drug. In addition, the biological effects of active component were also investigated in order to search for a new type of β₁AR antagonist. It will be a useful method for drug discovery as a leading compound resource.     

两种红光铱配合物的合成和电致发光性能研究

以二(二苯基磷酰)胺(Htpip)作为辅助配体,与主配体2-(2,4-二氟苯基)异喹啉和2-(4-三氟甲基苯基)异喹啉合成了红光铱磷光配合物Ir(dfpiq)2tpip和Ir(tfmpiq)2tpip并得到了晶体结构。在CH2Cl2中发射光谱主要是MLCT发射,峰位置分别为622和600 nm,量子效率分别为15%和17%,而HOMO/LUMO能级分别是-4.80/-2.58和-4.73/-2.57 eV。在1150~1300(V·cm-1)1/2电场范围,Ir(dfpiq)2tpip的电子迁移率为6.61~8.49×10-6cm2·V-1·s-1,Ir(tfmpiq)2tpip的电子迁移率为6.08~6.61×10-6cm2·V-1·s-1。ITO/TAPC(60 nm)/Ir-complex(15wt%):CBP(50 nm)/TPBi(60 nm)/LiF(1 nm)/Al(100 nm)中基于Ir(dfpiq)2tpip的器件最大安培效率和功率效率分别为4.71 cd·A-1和1.82 lm·W-1,12.0 V时达到的最大亮度为18 195 cd·m-2。基于Ir(tfmpiq)2tpip的器件最大安培效率和功率效率分别为3.47 cd·A-1和1.51 lm·W-1,12.4 V时达到的最大亮度为14 676 cd·m-2。     

硝基基团修饰的金属有机框架化合物的合成及晶体结构表征

分别以2种硝基羧酸配体EBNB(1,2-二(3-硝基苯甲酸)-乙烯)和NPA(3-硝基邻苯二甲酸)与BPY(4,4′-联吡啶)及金属锌反应,配位溶剂热法合成了2种具有硝基基团修饰的二核金属簇为基本构筑单元的金属有机框架化合物[Zn2(EBNB)2(BPY)2·2H2O]n(1)和[Zn2(NPA)2(BPY)2·H2O]n(2)。通过X-射线单晶衍射法测定了2种配合物的结构,其中配合物1属于三斜晶系,P1空间群,a=0.818 62(9)nm,b=1.142 20(14)nm,c=1.428 63(17)nm,α=96.803 0(10)°,β=93.045 0(10)°,γ=102.472(2)°,V=1.290 8(3)nm3,Z=2,Mr=595.81,Dc=1.533 g·cm-3,μ=1.01 mm-1,F(000)=608,T=293(2)K;配合物2属于三斜晶系,P1空间群,a=1.154 06(14)nm,b=1.190 86(16)nm,c=1.459 52(19)nm,α=98.029(1)°,β=98.749(1)°,γ=113.579(2)°,V=1.771 9(4)nm3,Z=2,Mr=879.35,Dc=1.648 g·cm-3,μ=1.43 mm-1,F(000)=892,T=293(2)K。同时也对2种配合物的发光性能进行了测试,测试结果表明2种配合物具有较好的荧光性能。     

A Facile and Practical Process for the Synthesis of Polysubstituted Furans from Alkynes Using Atmospheric Oxygen as a Terminal Oxidant

We present here a facile and practical procedure for the synthesis of tetrasubstituted furans from alkynes catalyzed by palladium acetate together with cupric acetate in acetic acid, using atmospheric oxygen as a terminal oxidant. Various internal aromatic alkynes afforded the target furans in satisfactory yield.     

Synthesis and acaricidal activity of strobilurin-pyrimidine derivatives简

Pyriminostrobin, a new acaricide, was discovered in our previous studies. Because introducing fluorine into organic compounds can increase bioactivity, pyriminostrobin was modified as a series of strobilurin-pyrimidine derivatives for biological screening. The compounds were characterized by 1H NMR, MS and elemental analysis. Preliminary bioassays demonstrated that compounds 7e and 7i exhibited significant control against Tetranychus cinnabarinus （Boisd.） at 0.625 mg L^-1, and their acaricidal potencies were higher than pyriminostrobin in a greenhouse. The relationship between structure and acaricidal activity was also studied.     

A hierarchical porous carbon membrane from polyacrylonitrile/polyvinylpyrrolidone blending membranes:Preparation,characterization and electrochemical capacitive performance

Novel hierarchical porous carbon membranes were fabricated through a simple carbonization procedure of well-defined blending polymer membrane precursors containing the source of carbon polyacrylonitrile （PAN） and an additive of polyvinylpyrrolidone （PVP）, which was prepared using phase inversion method. The as-fabricated materials were further used as the active electrode materials for supercapacitors. The effects of PVP concentration in the casting solution on structure feature and electrochemical capacitive performance of the as-prepared carbon membranes were also studied in detail. As the electrode material for supercapacitor, a high specific capacitance of 278.0 F/g could be attained at a current of 5 mA/cm2 and about 92.90% capacity retention could be maintained after 2000 charge/discharge cycles in 2 mol/L KOH solution with a PVP concentration of 0.3 wt% in the casting solution. The facile hierarchical pore structure preparation method and the good electrochemical capacitive performance make the prepared carbon membrane particularly promising for use in supercapacitor.