Monoterpenoids from the Fruit of Gardenia jasminoides

Eight new monoterpenoids, jasminoside J ( 1 ), jasminoside K ( 2 ), 6′‐O‐trans‐sinapoyljasminoside B ( 3 ), 6′‐O‐trans‐sinapoyljasminoside L ( 4 ), jasminosides M–P ( 5 – 8 ), together with three known analogues, jasminoside C ( 9 ), jasminol E ( 10 ), and sacranoside B ( 11 ), were isolated from the fruit of Gardenia jasminoides Ellis (Rubiaceae). Their structures were elucidated by spectral and chemical methods.     

Theoretical study of mechanism of cycloaddition reaction between dimethylmethylene carbene and formaldehyde

The cycloaddition mechanism of forming a polycyclic compound between singlet dimethylmethylene carbene(R1) and formaldehyde(R2) has been investigated with MP2/6‐31G* method, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated with CCSD(T)//MP2/6‐31G* method. From the potential energy profile, it can be predicted that the dominant reaction pathway of the cycloadditional reaction between singlet dimethylmethylene carbene and formaldehyde consists of two steps: (1) the two reactants(R1, R2) firstly form an energy‐enricheded intermediate (INT1a) through a barrier‐free exothermic reaction of ΔE = 11.3 kJ/mol. (2) Intermediate (INT1a) then isomerizes to a three‐membered product (P1) via a transition state (TS1a) with an energy barrier of 20.0 kJ/mol. The dominant reaction has an excellent selectivity and differs considerably from its competitive reactions in reaction rate. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

顶空进样GC-MS结合保留指数分析墨旱莲挥发性成分

采用顶空-气相色谱-质谱法(HS-GC-MS)对墨旱莲的挥发性成分进行检测,并结合保留指数对其分析鉴定。结果检测到60个组分,鉴定出33个可能的组分,占挥发性成分的70.0%。该研究为墨旱莲药材挥发性成分的指纹图谱研究奠定了基础。     

A comparative theoretical study of the reactivities of the Al+ and Cu+ ions toward methylamine and dimethylamine

A very recent laser ablation‐molecular beam experiment shows that an Al⁺ ion can react with a single methylamine (MA, CH₃NH₂) or dimethylamine (DMA, (CH₃)₂NH) molecule to form a 1:1 ion–molecule complex Al⁺[CH₃NH₂] or Al⁺[(CH₃)₂NH)], whereas a dehydrogenated complex ion Cu⁺[CH₃N] or Cu⁺[C₂H₅N] is detected, respectively, in the similar reaction for a Cu⁺ ion. Here, we show a comparative density functional theory study for the reactivities of the Al⁺ and Cu⁺ ions toward MA and DMA to reveal the intrinsic mechanism. It is found that the interactions of the Al⁺ ion with MA and DMA are mostly electrostatic, leading to the direct ion–molecule complexes, Al⁺? NH₂CH₃ and Al⁺? NH( CH₃)₂, in contrast to the non‐negligible covalent character in the corresponding Cu⁺‐containing complexes, Cu⁺? NH₂CH₃ and Cu⁺? NH( CH₃)₂. The general dehydrogenation mechanism for MA and DMA promoted by the Cu⁺ ion has been shown, and the preponderant structures contributing to the mass spectra of the product ions Cu⁺[CH₃N] and Cu⁺[C₂H₅N] are rationalized as Cu⁺? NHCH₂ and Cu⁺? N( CH₂)( CH₃). The presumed dehydrogenation reactions are also discussed for the Al⁺‐containing systems. However, the involved barriers are found to be too high to be overcome at low energy conditions. These results have rationalized all the experimental observations well. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Enantioselective henry reactions catalyzed by chiral N-metal complexes containing R(+)/S(−)-α-ethylphenyl amines

A series of novel N-metal complexes containing chiral α-ethylphenyl amines was synthesized and they catalyzed asymmetric Henry reactions affording products with high enantioselectivity.     

Ab initio study of mechanism of forming germanic bis-heterocyclic compound between germylene carbene (H2GeC:) and acetone

The mechanism of the cycloaddition reaction of forming germanic bis-heterocyclic compound between singlet germylene carbene and acetone has been investigated with MP2/6-31G* method, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by CCSD (T)//MP2/6-31G* method. From the potential energy profile, it can be predicted that the dominant reaction pathway of the cycloadditional reaction of forming germanic bis-heterocyclic compound consists of three steps: (1) the two reactants firstly form an intermediate INT4 through a barrier-free exothermic reaction of 181.4 kJ/mol; (2) INT4 further reacts with acetone (R2) to form an intermediate (INT5), which is also a barrier-free exothermic reaction of 148.9 kJ/mol; (3) INT5 then isomerizes to a germanic bis-heterocyclic product P5 via a transition state TS5 with an energy barrier of 53.3 kJ/mol.     

Controllable preparation and fluorescence properties of Y and Eu co-doped mesoporous silica

The controllable preparation and forming mechanism of rare-earth Y³⁺ and Eu³⁺ chemically co-doped fluorescent mesoporous silica were studied in detail. Their structures, morphologies, chemical compositions and emission properties were characterized and evaluated by small angle X-ray scattering, nitrogen adsorption/desorption measurements, high resolution transmission electron microscopy, inductive coupled plasma-atomic emission, X-ray photoelectron spectra and fluorescent spectroscopy. The results show that chemical composition of the resultant mesoporous materials were significantly affected by solution acidity condition, and can be effectively adjusted by varying the feed ratio of raw materials at a suitable solution acidity condition. These materials with a well-ordered two-dimensional hexagonal mesoporous structure and high specific surface area exhibit significantly broadened emission band from 526 to 682 nm and the fluorescent emission mechanism and influence of materials structure on optical properties were investigated.     

N-bromosuccinimide-fluorescein system for the determination of protein by flow injection chemiluminescence

A method for flow injection with chemiluminescence (CL) detection has been developed for the determination of proteins. It is based on the luminescence of the N-bromosuccinimide-fluorescein-protein system, where fluorescein is used as an energy transfer reagent in alkaline medium. The CL of the system is strongly enhanced by hexadecyl trimethyl ammonium bromide. Optimum conditions and possible mechanisms have been investigated. Under optimum experimental conditions, the linear range is from 0.4 to 40 µg·mL^?1 for egg albumin, 0.2 to 20 µg·mL^?1 for bovine serum albumin, and from 1 to 100 µg·mL^?1 for bovine hemoglobin. The detection limits are 37, 62, and 240 ng·mL^?1, respectively.     

Microfluidic techniques for dynamic single-cell analysis

Dynamic single-cell analysis is a very important and frontier research field of single-cell analysis. Microfluidic techniques have become new and effective tools for precise, high-throughput, automatic analysis of single-cell dynamic process. This review aims to give an overview of dynamic single-cell analysis methods based on microfluidic platforms, with emphasis on the recent developments of microfluidic devices and its application to real-time dynamic monitoring of the signal molecules release from single living cell with temporal and spatial resolution, dynamic gene expression in single cells, the cell death dynamic events at the level of a single cell, and direct cell—cell communication between individual cell pairs.     

A sensitive immunosorbent bio-barcode assay combining PCR with icELISA for detection of gonyautoxin 2/3

In the current study, we developed a nanosphere bio-barcode technology to detect trace gonyautoxin 2/3 (GTX 2/3). GTX 2/3-glucose oxidase (GOX) conjugates were first prepared as the coating antigen in a periodate reaction. Subsequently, gold nanoparticles (NP) dual-labeled with anti-GTX 2/3 monoclonal antibodies (Mab) and DNA oligonucleotides were synthesized via a one-step preparation method. Combining PCR with indirect competitive ELISA (icELISA), a novel immunosorbent bio-barcode assay was established utilizing the Mab-NP-dsDNA complex to convert enzymatic signals to DNA signals. Importantly, the limit of detection of the method was lower than 0.74 μg mL⁻¹. Thus, the immunosorbent bio-barcode assay is a rapid and high-throughput screening tool to detect GTX 2/3 in aquatic products.