Relationships of Surfactant Head Group Weight Fraction and Some Polarity Terms by Gas Chromatography

 Polarity, partition coefficient (K), methanol carbon number of surfactant ((CMeOH)S), and methanol carbon number of surfactant head group ((CMeOH)HG) are measured on six alkanolamides and five polyoxyethylenated long chain amines as stationary phases. From the measured methanol carbon numbers, polarity indices, (IP)S and (IP)HG, are calculated. The determined polarity terms are plotted against the head group weight fraction ( fHG ) of the investigated surfactants and several equations have been developed. The study reveals that the molecular structural gap between alkanolamides and polyoxyethylenated long chain amines diminished when HLB numbers of these surfactant classes are plotted against fHG values. Consequently, a general equation relating HLB and fHG is obtained.     

丙烯酸甲酯/4-丙烯酰胺基-2,2,6,6-四甲基哌啶光共聚合体系的竞聚率和序列分布研究

以丙烯酸甲酯(MA,M1)和4-丙烯酰胺基-2,2,6,6-四甲基哌啶(AATP,M2)溶液光共聚合体系为研究对象,采用1H-NMR手段测定了MA/AATP共聚物的组成,用Mayo-Lewis积分法和扩展Kelen-Tüdos方法计算的竞聚率分别为0.88相似文献   

SOLID STATE HIGH RESOLUTION ~(13)C NMR STUDY OF CHINESE MUDSTONE KEROGENS

Using ~(13)C CP MAS TOSS DD NMR, some rules governing the variations of structureparameter and fractional contents for various aliphatic carbon in the mudstone kerogensburied in different depths in China are first reported in this paper, and the preliminarystudies on their natural evolution as well for the formation of oil and gas have been made.The influence of T_(CP), T_(CH), f_(rsc) on quantity measurement of CP in kerogens is discussed.     

微环电极理论

近几年来,微电极的应用得到迅速发展,但由于混合边界条件的存在,微电极稳态和暂态问题的数学处理极为复杂.过去,微电极上不可逆和准可逆过程主要采用近似方法研究.自文献利用贝塞尔级数处理微盘电极稳态行为以后,两种可用来精确处理微     

Effect of wine and vinegar processing of Rhizoma Corydalis on the tissue distribution of tetrahydropalmatine, protopine and dehydrocorydaline in rats

Vinegar and wine processing of medicinal plants are two traditional pharmaceutical techniques which have been used for thousands of years in China. Tetrahydropalmatine (THP), dehydrocorydaline (DHC) and protopine are three major bioactive molecules in Rhizoma Corydalis. In this study, a simple and reliable HPLC method was developed for simultaneous analysis of THP, DHC and protopine in rat tissues after gastric gavage administration of Rhizoma Corydalis. The validated HPLC method was successfully applied to investigate the effect of wine and vinegar processing on the compounds' distribution in rat tissues. Our results showed that processing mainly affect the T(max) and mean residence time (MRT) of the molecules without changing their C(max) and AUC(0-24)( )(h) Vinegar processing significantly increased the T(max) of DHC in heart, kidney, cerebrum, cerebrellum, brain stem and striatum and prolonged the T(max) of protopine in brain. No significant changes were observed on the T(max) of THP in rat tissues after vinegar processing. Wine processing reduced the T(max) of protopine and DHC in liver and spleen and T(max) of protopine in lung, but increased the T(max) of THP in all the rat tissues examined. To our knowledge, this is the first report on the effects of processing on the tissue distribution of the bioactive molecules from Rhizoma Corydalis.     

一种抗偏头痛复方制剂体外溶出度的比较研究

 A novel in vitro dissolution profile was developed for formulated drug in combinational form containing naproxen sodium (NAP) and sumatriptan succinate (SUMA). This study was performed to understand the dissolution of the drug in the physiological temperature and pH. Dissolution testing was performed using USP 29 type II testing apparatus rotating at 50 r/min, in 900 mL deaerated buffer （pH 1.2, 4.5 and 6.8） which was maintained at (37±0.5) ℃. Quantification was performed using a developed and validated high performance liquid chromatographic (HPLC) method. Aceclofenac (ACE) was used as internal standard. SUMA, ACE and NAP were eluted at 4.8, 5.7 and 7.9 min, respectively. As expected for enteric coated immediate release (IR) tablets, the dissolution of NAP and SUMA was rapid and essentially complete within 2 h using phosphate buffer (pH 6.8). The comparison of the dissolution profiles was realized by model independent approach using a difference factor (f1), similarity factor (f2) and dissolution efficiency (DE). Statistical results showed the profiles were similar to the reference and the test products. Hence, this method demonstrated to be adequate for in vitro studies of NAP and SUMA in the combinational dosage form, since there is no official monograph, collaborating to the official codes.     

Two-photon absorption properties of 2,6-bis(styryl)anthracene derivatives: effects of donor-acceptor substituents and the pi center

A series of 2,6- and 2,7-bis(styryl)anthracene derivatives with the donors at the styryl group and acceptors at the 9,10-positions have been synthesized, and their two-photon cross sections (Phidelta(max)) were determined. These compounds exhibit a peak two-photon absorptivity (delta(max)) in the range of 700-2500 GM at 780-1030 nm. Values of lambda(max) and Stokes shifts increase as the acceptor is changed to a stronger one. There is also a parallel increase in lambda(2)max and delta(max) with the same variation of the chromophore structure. Both lambda (2)(max)and Phidelta(max) have been optimized by introducing donor-substituted styryl groups at the 2,6-positions and p-cyanophenyl groups at the 9,10-positions, respectively. The effect of a pi center on the two-photon absorption properties has been assessed by comparing the existing data for a variety of D-pi-D derivatives.     

Bioluminescence color determinants of Phrixothrix railroad-worm luciferases: chimeric luciferases, site-directed mutagenesis of Arg 215 and guanidine effect

Chimeric proteins were produced using the green light-emitting luciferase of Phrixothrix vivianii (PxGr: lambda max = 548 nm) and the red light-emitting luciferase of Phrixothrix hirtus (PxRe: lambda max = 623 nm). Constructs containing residues 1-344 of the red light-emitting luciferase with residues 345-545 of the green light emitting one emitted red light (PxReGr; lambda max = 613 nm), while the reverse emitted green light (PxGrRe; lambda max = 552 nm). From these results we conclude that the region 1-344 determines the color of bioluminescence (BL) in railroad-worm luciferases, and that residues above 344 are not involved. The substitution R215S in the green light-emitting luciferase (PxGr) resulted in a approximately 40 nm redshift on the BL spectrum (lambda max = 585 nm) and an associated decrease of activity, whereas the same mutation in PxRe luciferase had little effect. Guanidine was shown to cause blueshifts in the BL spectra and stimulate the activity of the red-emitting luciferases (from lambda max = 623 to lambda max = 600 nm) and in PxGr R215S (from lambda max = 585 to lambda max = 560 nm) mutant luciferase, but not in the green-emitting luciferases, suggesting that guanidine can simulate positively charged residues involved in BL color determination.     

Synthesis and optical properties of all-trans-oligodiacetylenes

A new series of pure and highly soluble oligodiacetylenes (ODAs) was synthesized in high yield and on a multi-milligram scale by a sequence of Sonogashira reactions with a strongly reduced level of homocoupling. The lambda(max) and epsilon(max) of these ODAs show an increase with both chain elongation and solvent polarity. A plot of lambda(max) absorption versus 1/CL (CL=conjugation length) was shown to be linear. The lambda(max) converges to 435 nm for the longest members of the series at micromolar concentration. This reveals that the longest wavelength absorption observed for PDA chains (lambda(max) up to 700 nm) is due to aggregation effects. The fluorescence quantum yield increased from monomer to trimer and decreased for longer ODAs. A similar trend is found for the lifetime of fluorescence with a maximum of 600 ps for the trimer. The observed linearity of the rotational correlation time with the oligomer length implies that the ODA chains in solution lack significant geometrical changes. This implies that the ODAs in solution are fully stretched molecular rods of up to 4 nm in length.     

Coloured complexes of all-trans-retinal with benzocaine and other local anaesthetics

Coloured Schiff base complexes with lambda max values of 500 nm or above were formed between the visual pigment all-trans-retinal and the local anesthetics procaine (lambda max = 533 nm), benzocaine (4-amino-benzoic acid ethyl ester, lambda max = 535 nm), 3-amino-benzoic acid ethyl ester (lambda max = 500 nm) and 2-amino-benzoic acid ethyl ester (lambda max = 509 nm) in methanol acidified with HCl. The anaesthetics lidocaine and urethane failed to form coloured compounds with lambda max values greater than 500 nm under the same conditions. The relevance of these observations to the effect of anaesthetics on the visual pigments is discussed.     

Letter: correlation between phosphorylation ratios by matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis and enzyme kinetics

To identify the correlation between the phosphorylation ratios by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF MS) analysis and enzyme kinetics (K(m), V(max), and V(max)/K(m)) is important to understand whether MALDI-TOF MS can be applied for monitoring the properties of peptides that are substrates of protein kinases. The correlation between phosphorylation ratios and enzyme kinetics was examined using peptides for protein kinase C (PKC) and for 60 kDa phosphoprotein, encoded by the cellular sarcoma gene (c-Src). Phosphorylation ratios, analyzed by MALDI-ToF MS, showed higher correlation coefficient (r = > +0.7) for V(max)/K(m) compared with that (r = < -/+0.6) for K(m) or V(max). For ion modes, a higher correlation coefficient between phosphorylation ratios and V(max)/K(m) was identified in the positive mode (r = > +0.7) compared to that in the negative mode (r = < +0.5). These results suggest that MALDI-ToF MS is a useful tool to evaluate V(max)/K(m) of peptides for protein kinases.     

Water solubilization capacity of mixed reverse micelles: effect of surfactant component, the nature of the oil, and electrolyte concentration

Solubilization of water in mixed reverse micellar systems with anionic surfactant (AOT) and nonionic surfactants (Brijs, Spans, Tweens, Igepal CO 520), cationic surfactant (DDAB)-nonionic surfactants (Brijs, Spans, Igepal CO 520), and nonionic (Igepal CO 520)-nonionics (Brijs, Spans) in oils of different chemical structures and physical properties (isopropyl myristate, isobutyl benzene, cyclohexane) has been studied at 303 K. The enhancement in water solubilization has been evidenced in these systems with some exceptions. The maximum water solubilization capacity (omega(0,max)) in mixed reverse micellar systems occurred at a certain mole fraction of a nonionic surfactant, which is indicated as X(nonionic,max). The addition of electrolyte (NaCl or NaBr) in these systems tends to enhance their solubilization capacities further both at a fixed composition of nonionic (X(nonionic); 0.1) and at X(nonionic,max) at 303 K. The maximum in solubilization capacity of electrolyte (omega(max)) was obtained at an optimal electrolyte concentration (designated as [NaCl](max) or [NaBr](max)). All these parameters, omega(0,max) vis-a-vis X(nonionic,max) and omega(max) vis-a-vis [NaCl](max), have been found to be dependent on the surfactant component (content, EO chains, and configuration of the polar head group, and the hydrocarbon moiety of the nonionic surfactants) and type of oils. The conductance behavior of these systems has also been investigated, focusing on the influences of water content (omega), content of nonionics (X(nonionic)), concentration of electrolyte ([NaCl] or [NaBr]), and oil. Percolation of conductance has been observed in some of these systems and explained by considering the influences of the variables on the rigidity of the oil/water interface and attractive interactions of the surfactant aggregates. Percolation zones have been depicted in the solubilization capacity vs X(nonionic) or [electrolyte] curves in order to correlate with maximum in water or electrolyte solubilization capacity. The overall results, obtained in these studies, have been interpreted in terms of the model proposed by Shah and co-workers for the solubility of water in water-in-oil microemulsions, as their model proposed that the two main effects that determine the solubility of these systems are curvature of the surfactant film separating the oil and water and interactions between water droplets.     

Influence of steric factors on exciplex energy and magnetic field effect

With the advent of spin chemistry, magnetic field effect (MFE) on exciplex luminescence has emerged as an important domain of research. MFE is a diffusion controlled phenomenon and hence is solvent dielectric (epsilon) dependent. It maximizes at a particular epsilon (epsilon(max)) for a specific exciplex system. Various attempts have been made to explain the variation of this epsilon(max) from one exciplex to another. In our present work we have succeeded for the first time to enmark the energy of exciplex (E(ex)) as the prime factor in determining the epsilon(max). We have indicated a definite inverse correlation (1:1) between epsilon(max) and E(ex). We have also tried to correlate some parameters that are important in exciplex formation, e.g. Charton's steric constant (nu(c)), repulsive energy (R(e)) and E(ex).     

碳素钢钝化的线性电位扫描法问题

电位扫描法是一种基本的电化学研究方法。前人对此作了大量的研究。对于具有表面转化步骤的复杂电极过程,尤其是阳极过程,Srinivasan等作了扫描电位—电流的理论分析,导出了峰值电流(I_(max)或i_p)与扫描速度的平方根(v~(1/2))成正比的近似数学关系式,可较好地应用于有机物电化学吸附,以及H_2、O_2在某些金属表面的电化学吸附。金属钝化过程是金属阳极溶出过程中含氧金属粒子在金属表面生成化学吸附层并且继续发展形成表面     

Dielectrophoresis microbial characterization and isolation of Staphylococcus aureus based on optimum crossover frequency

Characterization of antibiotic-resistant bacteria is a significant concern that persists for the rapid classification and analysis of the bacteria. A technology that utilizes the manipulation of antibiotic-resistant bacteria is key to solving the significant threat of these pathogenic bacteria by rapid characterization profile. Dielectrophoresis (DEP) can differentiate between antibiotic-resistant and susceptible bacteria based on their physical structure and polarization properties. In this work, the DEP response of two Gram-positive bacteria, namely, Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-susceptible S. aureus (MSSA), was investigated and simulated. The DEP characterization was experimentally observed on the bacteria influenced by oxacillin and vancomycin antibiotics. MSSA control without antibiotics has crossover frequencies ($f_{x0}$) from 6 to 8 MHz, whereas MRSA control is from 2 to 3 MHz. The $f_{x0}$ changed when bacteria were exposed to the antibiotic. As for MSSA, the $f_{x0}$ decreased to 3.35 MHz compared to $f_{x0}$ MSSA control without antibiotics, MRSA, $f_{x0}$ increased to 7 MHz when compared to MRSA control. The changes in the DEP response of MSSA and MRSA with and without antibiotics were theoretically proven using MyDEP and COMSOL simulation and experimentally based on the modification to the bacteria cell walls. Thus, the DEP response can be employed as a label-free detectable method to sense and differentiate between resistant and susceptible strains with different antibiotic profiles. The developed method can be implemented on a single platform to analyze and identify bacteria for rapid, scalable, and accurate characterization.     

稀释稳定剂对有机过氧化物热分解的压力效应

小型密闭压力试验;压力行为;稀释稳定剂对有机过氧化物热分解的压力效应     

N-亚水杨基亮氨酸3d金属配合物的合成及薄层色谱与紫外光谱研究

合成了亮氨酸水杨醛希夫碱及其与Ｍｎ（Ⅱ）,Ｃｏ（Ⅱ）,Ｎｉ（Ⅱ）,Ｃｕ（Ⅱ）,Ｚｎ（Ⅱ）的配合物。元素分析和摩尔电导测定的结果证明,亮氨酸水杨醛希夫碱３ｄ金属配合物配位比为１１,配合物在ＤＭＦ中为非电解质。在硅胶Ｇ板上,以乙酸乙酯－甲醇－丙酮－水－乙酸（４．４４３．３３２．２２０．２５０．１２,Ｖ／Ｖ）为流动相,研究了配合物的薄层色谱行为,各组分配合物的比移值Ｒｆ值相差较大,得到满意的分离,且Ｒｆ值按下列顺序递增Ｍｎ＜Ｚｎ＜Ｎｉ＜Ｃｕ＜Ｃｏ。讨论了系列配合物薄层色谱Ｒｆ与紫外光谱Ｒ带λｍａｘ变化关系的规律     

Two photon absorption properties of 1,3,5-tricyano-2,4,6-tris(styryl)benzene derivatives

Two-photon absorption (TPA) properties of 1,3,5-tricyano-2,4,6-tris(styryl)benzene derivatives have been investigated. Comparison of the absorption and fluorescence spectra reveals that these compounds show large Stokes shifts, which increase gradually as the conjugation length increases. One-photon absorption and excitation spectra are similar except that the latter exhibit several peaks near lambda(max). It is also found that the one- and two-photon-induced fluorescence excitation spectra are quite similar, which indicates that the one- and two-photon allowed-excited states are the same. The peak TPA cross section values (delta(max)) measured with nanosecond pulses by the two-photon-induced fluorescence method are in the range (50-2620) x 10(-50) cm4 s/photon. The delta(max) value increases as the donor strength and conjugation length increase. A linear relationship is observed between delta(max) and beta, and this delta-beta relationship is found to serve as a useful synthetic strategy for the design of novel TPA dyes with the octupolar structure.     

Thiophene-containing Pechmann dyes and related compounds: synthesis, and experimental and DFT characterisation

Attaching 2-thienyl residues to the Pechmann dye core chromophore (5,5-exo-dilactone situated around a C-C double bond) results in a novel magenta-coloured compound (UV/Vis spectroscopy λ(max) =570 nm in CHCl(3)), which can be rearranged to a yellow 6,6-endo-dilactone (λ(max) =462 nm in CHCl(3)). Single and double amidation results in pronounced redshift in the 5,5-exo series (violet, λ(max) =570 nm and blue, λ(max) =606 nm in CHCl(3), respectively) but pronounced blueshift in the 6,6-endo series (yellow, λ(max) =424 nm and pale yellow bordering on colourless, λ(max) =395 nm in CHCl(3), respectively). Incorporation of a 3-alkyl substituent on the thiophene ring allows for sharp increase of solubility in organic solvents concomitant with fine-tuning of the colour: a redshift in 5,5-exo-dilactones but a blueshift in 5,5-exo-dilactams. DFT computations demonstrate that both lactone classes are planar regardless of the presence of a 3-alkyl group. The lactam derivatives are non-planar: the thiophene-core chromophore dihedral angles increase on going from 5,5-exo to 6,6-endo and from thiophene to 3-alkyl thiophene. Depending on the core heteroatom (O vs. N-alkyl), ring junction (5,5-exo vs. 6,6-endo) and 3-thiophene substituent (H vs. alkyl), two, three, four or six conformers are possible. All of these conformers were characterised by DFT and were found to be very close in energy at both IEFPCM/B3LYP/DGDZVP and SMD/M06/DGDZVP levels of theory. Within each conformer set, the HOMO and LUMO energies were within 0.05 eV and the predicted λ(max) values (TD-DFT) within 10 nm, and this implies low sensitivity of the optical and electronic properties to conformation. Cyclic voltammetry measurements of selected compounds demonstrated good matching to the HOMO and LUMO energies from IEFPCM/B3LYP/DGDZVP computations. M06-2X was the best DFT functional for TD-DFT, giving predicted λ(max) values within about 20 nm.     

胶束形成的分形研究

提出了测定胶束质量分维的两种新方法即粘度法和GPC－LALLS联机法，随后从动态光散射数据计算了离子型胶束SDS的分维，这些实验数值之间能互相印证．建立了放束形成过程的Laplace分形理论，计算得分维D＝1.54（二级），作高级计算的分维D＝1.67与前面实测值基本相符，另外，从唯象理论角度，讨论了胶束的多重分形及其热力学行为，发现有两个相变点β_c＝-4和β_c＝-1．并认为这两个转折分别对应着单分子<=>分形胶束<=>经典胶束结构之间的转变．