Expedient Synthesis of Epigoitrin From L-Ascorbic Acid

Epigoitrin is the main bioactive constituent of an important traditional Chinese herbal medicine, Radix isatidis. Reported pharmacological effects of epigoitrin include antiviral, anticancer, and antithyroid activities. Extensive biological exploration of epigoitrin was constrained by the limited natural source. This article describes our continued effort toward chemical preparation of epigoitrin from the readily available L-ascorbic acid. Our new developed synthetic route is composed of nine steps, with an overall yield of 17%.     

高效液相色谱-电感耦合等离子质谱法分析海洋沉积物中有机锡的形态

建立了高效液相色谱-电感耦合等离子质谱(HPLC-ICP-MS)测定海洋沉积物中二丁基锡(DBT)、三丁基锡(TBT)、二苯基锡(DPhT)及三苯基锡(TPhT)的形态分析方法。通过改变流动相组分比例,使4种有机锡达到基线分离。比较不同提取方法对标准参考物质PACA-2中有机锡的提取效率。以V(乙腈)∶V(H2O)∶V(乙酸)=55∶33∶12(含5%三乙胺,pH 3.0)为提取剂时,超声提取效率最高(>91.5%),其加标回收率均大于96%。本方法对DBT,TBT,DPhT和TPhT的检出限分别达到0.7,0.75,0.45和0.4μg/kg。对浓度范围为0.5～100μg/kg有机锡混合标准溶液进行测定,4种有机锡回归系数均大于0.998。利用本方法对几种海洋沉积物样品和海产品中的有机锡进行测定,在部分沉积物样品中检测到了DBT和TBT,部分海产品中测到了少量TBT和TPhT。     

Synthesis and Crystal Structure of a Novel Ethyl 5-(4-(2-Phenylacetamido)phenyl)-1H-pyrazole-3-carboxylate as an Acrosin Inhibitor

The title compound (ethyl5-(4-(2-phenylacetamido)phenyl)-1H-pyrazole-3-carboxy- late, C20H19N3O3) was synthesized by the reaction of Claisen condensation, cyclization, reduction and acylation. The structure was characterized by X-ray diffraction, MS, NMR and IR. It belongs to the monoclinic system, space group C2/c with a = 22.723(9), b = 9.324(4), c = 18.890(8) , β = 114.259(6)°, V = 3649(3) 3, Dc = 1.272 Mg·m-3, Z = 8, Mr = 349.38, μ = 0.087 mm-1, F(000) = 1472, the final R = 0.0615 and wR = 0.1643. The biological test shows that the title compound has a moderate acrosin inhibition activity.     

Multifunctional manganese carbonate microspheres with superparamagnetic and fluorescent properties: synthesis and biological application

Multifunctional manganese carbonate microspheres with superparamagnetic and fluorescent properties were fabricated and used as biological labels. The Fe(3)O(4)@MnCO(3) microspheres were synthesized by direct co-precipitation without any linker shell. The Fe(3)O(4)@MnCO(3) microspheres have uniform size distribution and rough surface, which provides a promising template for the assembly of polyelectrolytes (PEs) and CdTe quantum dots (QDs). A luminescent CdTe shell was observed in Fe(3)O(4)@MnCO(3)@PE-CdTe spheres by confocal fluorescence imaging. With excellent solubility in water and rough surfaces, the multifunctional microsphere offers a friendly microenvironment for immobilization of α-fetoprotein (AFP) antibodies (Ab(2)) to fabricate Fe(3)O(4)@MnCO(3)@PE-CdTe-Ab(2) architecture. By using the Fe(3)O(4) @MnCO(3)@PEs-CdTe-Ab(2) bioconjugate as a label, a promising and versatile platform for fluorescence imaging and electrochemical immunosensing of cancer biomarker AFP was developed. The prepared electrochemical immunosensor shows high sensitivity and selectivity with a detection limit of 0.3 pg mL(-1).     

Enantioselective intramolecular Rauhut-Currier reaction catalyzed by chiral phosphinothiourea

Chiral organophosphine-catalyzed enantioselective Rauhut-Currier reaction has been disclosed for the first time. With L-valine-derived phosphinothiourea, the intramolecular Rauhut-Currier reaction of bis(enones) was achieved in good yields (up to 99%) with excellent enantioselectivities (up to 99.4% ee).     

Morphology and interference color in spherulite of poly(trimethylene terephthalate) copolyester with bulky linking pendent group

A novel phosphorus-containing copolyester (PTTP), poly(trimethylene terephthalate) (PTT) copolyester with a bulky linking pendent group of 9,10-dihydro-10-[2,3-di(hydroxycarbonyl) propyl]-10-phosphaphenanthrene-10-oxide (DDP) was prepared, and its crystallization, crystal morphology and interference color were investigated in this article for the first time. Differential scanning calorimeter (DSC) results showed that with the increase of DDP content, the melting point (T(m)) and crystallization ability of PTTP decreased. WAXD results suggests that the three samples share one crystal structure, however the crystallinity decreases with increasing DDP content. Polarized optical microscope (POM) observation indicated that the samples showed non-banded spherulites at a lower and higher temperature, and banded spherulites at the middle temperature range. From the micrographs obtained from scanning electronic microscopy (SEM) and atomic force microscopy (AFM), ringed patterns with many defects could be found for samples with higher DDP contents, which crystallized at a lower temperature, and a transformation from square-shaped spherulites to circular spherulites was noted for samples with higher DDP contents, which crystallized at a higher temperature. The interference color of the spherulites was also studied and it was shown that with the increase of film thickness or decrease of DDP content, the spherulites became more colorful under POM observation, indicating that the hindering effect and randomness caused by incorporating the DDP monomer with a bulky pendent group into the PTT molecular chain exhibited a negative influence on the molecular mobility and crystallization ability of the copolyester, and led to the formation of the defective band morphology and the less colorful interference color of the PTTP spherulites.     

Computations of wall distances by solving a transport equation

Computations of wall distances still play a key role in modern turbulence modeling. Motivated by the expense involved in the computation, an approach solving partial differential equations is considered. An Euler-like transport equation is proposed based on the Eikonal equation. Thus, the efficient algorithms and code components developed for solving transport equations such as Euler and Navier-Stokes equations can be reused. This article provides a detailed implementation of the transport equation in the Cartesian coordinates based on the code of computational fluid dynamics for missiles (MICFD) of Beihang University. The transport equation is robust and rapidly convergent by the implicit lower-upper symmetric Gauss-Seidel (LUSGS) time advancement and upwind spatial discretization. Geometric derivatives must also be upwind determined to ensure accuracy. Special treatments on initial and boundary conditions are discussed. This distance solving approach is successfully applied on several complex geometries with 1-1 blocking or overset grids.     

共振和非共振情况下非简并双光子Tavis-Cummings模型中原子与原子之间的纠缠演化

针对共振和非共振情况讨论了非简并双光子Tavis-Cummings(T-C)模型中原子与原子之间的纠缠演化,得到纠缠度的解析表达式.基于两类型不同的初态,详细分析了光场本征频率、原子跃迁频率以及原子与原子间偶极相互作用对纠缠的影响,并比较了共振和非共振情况下的纠缠演化行为.     

Bremsstrahlung neutrino energy loss for ~(24)Mg, ~(28)Si, ~(32)S, ~(40)Ca, ~(56)Fe in strong electron screening

Based on WeinbergoSalam theory the bremsstrahlung neutrino energy loss for nuclei ~(24)Mg, ~(28)Si, ~(32)S, ~(40)Ca and ~(56)Fe are investigated in strong electron screening. Our results are compared with those of Dicus' and show that the latter are higher by 2 orders of magnitude in the density-temperature region of 10~8 g/cm~3 ≤ρ/μ_e≤10~(11) g/cm~3 and 2.5 ≤ T_9 ≤4.5. On the other hand, the factor C shows that the maximum differences are 99.16%, 99.13%, 99.12%, 99.055%, 99.040% corresponding to the nuclei ~(24)Mg, ~(28)Si, ~(32)S, ~(40)Ca and ~(56)Fe.     

Bremsstrahlung neutrino energy loss for ^24Mg, ^28Si, ^32S, ^40Ca, ^56Fe in strong electron screening

Based on Weinberg-Salam theory the bremsstrahlung neutrino energy loss for nuclei ^24Mg, ^28Si,^32S, ^40Ca and ^56Fe are investigated in strong electron screening. Our results are compared with those of Dicus＇ and show that the latter are higher by 2 orders of magnitude in the density-temperature region of 10^8 g/cm^3 ≤p/μe ≤ 10^11 g/cm^3 and 2.5≤ T9≤ 4.5. On the other hand, the factor C shows that the maximum differences are 99.16%, 99.13%, 99.12%, 99.055%, 99.040% corresponding to the nuclei ^24Mg, ^28Si, ^32S, ^40Ca and ^56Fe.