Kinetic treatment of unsegmented flow systems : Part 2. Detailed Treatment of Flow-Injection Systems with Gradient Chamber

A kinetic model is utilized for a detailed mathematical treatment and experimental evaluation of single-channel and dual-channel flow injection systems that include a gradient chamber. The kinetic model includes three distinct stages in the process, namely clearing reactant from the gradient chamber by first portions of sample, continued entry of sample into the gradient chamber, and decrease of determinant concentration in the gradient chamber via dilution and reaction with reagent. Equations predict entirely different behavioral patterns for different conditions and these predictions are verified experimentally for a wide range of conditions. The data show that the variable-time kinetic model is superior to the titration models previously utilized to describe these flow systems. The principal limitation of the kinetic equations involves an assumption of plug flow that is not completely valid. The extent of deviations from ideal behavior depend on conditions, but are negligible at low concentrations (0–50 mmol l^-1) and can be 10% or larger at higher concentrations (100 mmol l^-1). While equations are not exact, they are useful in predicting performance characteristics for a variety of conditions and experimental approaches.     

计算机模式识别法在类风湿中医证侯的研究

根据计算机模式识别的马氏(Mahalanobis)距离判别法，用BASIC等语言缩制的IBM-PC等徽机适用的多元统计判别程序将健康人分别与类风湿性关节炎的寒热错杂型、寒湿阻络型及肝肾两虚型的发样徽量元素Zn、Fe、Cu、Cd及Zn／Cu五种因素进行分类判别．结果表明以Zn、Ft、Zn／Cu为特征参量．健康人与寒热情杂型类风温性关节炎患者分类准确亭为95．6%，而分别以Zn、Cu和Zn，Fe、Cu为特征参量．健康人与寒湿阻络型和肝肾两虚型患者分类准确率分别为100％和90．2％．说明以Fe、Cu、Zn(或Zn／Cu)组成的微量元素谱含量，在不同中医证型的类风温性关节炎和健康中是有差异的。     

Vibronic spectra of charge transfer excitons and of mixed charge transfer and Frenkel excitons

The linear absorption spectra in the excitonic and vibronic regions in the case of mixing of Frenkel excitons (FEs) and charge-transfer excitons (CTEs) have been theoretically studied for the exciton parameters of the crystals of MePTCDI and PTCDA. Two coupling parameters for the exciton–phonon coupling are introduced: the FE–phonon coupling and the CTE–phonon coupling. The main features of the vibronics in the absorption spectra are the following: (a) the existence of a doublet structure in the vibronic spectra of CTEs; (b) the vibronic levels of the FE at intermediate values of both coupling parameters are located in the continuum of the many-particle exciton–phonon states which makes its absorption line wide and flat; (c) in the case of strong coupling (coupling constants larger than 1) a doublet of bound states appears above this continuum; (d) in the case of vanishing CTE–phonon coupling the vibronics of the charge transfer excitons practically disappear in the absorption spectra.     

Wannier-type atomic orbitals for periodic systems

The results of an application of Wannier-type atomic orbitals for calculations of local properties of electronic structure for periodic systems (atomic charges and covalencies, bond orders and total valencies), published earlier by the authors, are summarized. The numerical results are given for bulk crystals with the perovskite structure ATiO₃, A=Sr,Ba,Pb and LaMnO₃ (the Bloch functions are calculated in LCAO basis), for bulk MgO crystal (the Bloch functions are calculated both in LCAO and PW basis) and for the two periodic slab models of surfaces (001) of MgO and (110) of rutile TiO₂.     

The use of fluorescence in determining formation constants of complexes : Part II. Complexes which fluoresce

Four different methods for the calculation of the formation constants of fluorescing complexes are discussed. The methods were used to determine constants for the complexes of aluminum(III), gallium(III) and indium(III) with 8-quinolinol-5-sulfonate anion.     

Simultaneous determination of chromium and silicon in steel by 14-mev neutron activation analysis

Chromium and silicon are determined simultaneously in steel by 14-MeV neutron activation analysis. The activities of ⁵²V(E_γ=1.43 MeV,T_{$\text{1}\text{2}$}=3.76 min) from ⁵²Cr(n,p)⁵²V and ²⁸Al (E_γ=1.78 MeV; T_{$\text{1}\text{2}$}=2.24 min) from ²⁸Si(n,p)²⁸Al are evaluated by mixed γ-ray spectrometry. The influence of manganese and phosphorus, the main interfering elements, is negligible for most stainless steels. The count rate should be limited, to avoid ⁵²V pulse pile-up effects interfering in the ²⁸Al energy region. Precisions in the 2-10% range are reached, depending on the concentrations, for a 10-min analysis time. Results for a series of steel samples are compared with industrial analyses.     

甲状腺机能亢进症头发锌、硒、钒、锂、锗5种微量元素的动态变化

测定了２４例甲亢治疗前后及３０例健康对照的头发锌、硒、钒、锂及锗的含量，发现未治疗的甲亢头发锌、硒、钒、锂及锗含量较对照组低，Ｚｎ、Ｓｅ、Ｌｉ、Ｇｅ，Ｐ＜０．００１，Ｖ，Ｐ＜０．０１．甲亢经６～１２周抗甲亢药物治疗后．头发中５种元素均较治疗前上升（Ｐ＜０．００１），且头发钒和锂含量治疗后已达到对照组水平，Ｖ，Ｐ＞０．２，Ｌｉ，Ｐ＞０．１，而头发锌、晒及锗含量治疗后仍低于对照组（Ｐ＜０　．００１）．结论：甲亢头发锌、硒、钒、锂及锗含量降低．经６～１２周抗甲亢治疗可使头发钒及锂含量恢复正常水平，而其余３种元素则可能需要更长时间的抗甲亢治疗才能恢复至正常水平。     

Recherche d'une description structurale des de´compositions endothermique Solide 1 → Solide 2 + gaz. I. Structure cristalline de l'oxalate de baryum 2BaC2O4, H2O

2BaC₂O₄ · H₂O (M = 468.73) is triclinic, space group P1, with a = 9.312(1) A?, b = 9.649(1) A?, c = 6.188(1) A?, α = 90.13(2)°, β = 95.36(2)°, γ = 125.18(2)°, Z = 2, D_m = 3.48; C_x = 3.51g · cm^?3. The position of the Ba atom was determined from a Patterson function. A subsequent Fourier synthesis clearly revealed the position of all C and O atoms in the structure. Refinement of the MoKα diffractometer data by a least-squares method using full matrix gave R = 0.065. The structure presents two remarkable characteristics: (a) We distinguish two types of (C₂O₄)^2? ions. The first are planar, the second are notably separated from the plane configuration (deviation = 30°); this deformation is of a steric origin. (b) The water molecules are located in channels parallel to [001]. They enter in the coordination of one of the Ba²⁺ ions but do not exchange any strong hydrogen bond with oxygen atoms which surround them.     

The electronic structure of heteroaromatic molecules; non-empirical calculations and photoelectron spectra for the isomeric-thiazoles and -thiadiazoles

The He(I) and MgKα photoelectron spectra are reported for the isomeric thiazoles, and He(I) spectra for the isomeric-thiadiazoles. Marked fine structure is apparent on some of the spectra. Comparison with the earlier spectra for thiophen and the azoles, and with ab initio calculations for the seven compounds, has led to assignment of the spectra. The calculations suggest that 1,3,4-thiadiazole is less aromatic than the other title compounds. As expected, the role of the 3d_s orbitals is found to be that of polarisation functions for all of the compounds, but inclusion of these orbitals leads to much better agreement with the observed dipole moments, both in magnitude and direction.     

On the mechanism of ion evaporation from solutions with the help of strong electric field

Mechanism of ion evaporation from solutions with help of strong electric field has been studied in detail. The mechanism includes the following steps: (1) the crests of capillary waves at a surface of liquid are drawn in liquid needles (Tonks–Frenkel’s instability), (2) strong local electric fields are originated at the tips of these needles, which are centers of evaporation of ions from solutions, (3) the potential barrier at the tips of these needles is lowered essentially because of Shottky’s effect, which leads to the essential increase of the probability of ion evaporation from solutions.     

肿瘤患者放疗前后血清八种微量元素含量的研究

对临床、病理、放射线或CT检查确诊的82名癌肿患者，在放疗前后和对42名健康人进行了微量元素铁、锌、铜、锰、硒，铬、钴、镍的分析。研究结果显示：1．癌肿患者血清铜、镍、锰、铬、钴的含量比健康人高，而血清锌、铁、硒的含量却比健康人低；2．血清Cu／Zn、Cr／Zn、Co／Zn、Ni／Zn的比值癌肿患者均比健康人高，而Fe、Zn、Se／Zn的比值却相反。因此，可根据血清铜升高、血清锌降低，血清铜／锌比值升高的特点。用于癌肿的早期诊断；3．癌肿患者放疔后血清铁、锌含量进一步下降，铜、锰、铬的含量也出现降低，唯有硒的含量有所上升。因此，放疗时应注意补充铁、锌、铜元素。     

Seed Oils of Fifteen Ebenus Taxa Growing in Turkey

Oil yields and compositions from seeds of 15Ebenustaxa growing in Turkey were investigated. The yields were found between 4.0% and 13.0%. The seeds ofE. Barbigerashowed the highest whileE. Plumosavar.plumosashowed the lowest yield of oil among the 15 taxa investigated. GC/MS showed that linoleic acid (42.8-55.6%), palmitic acid (13.8-23.6%), and oleic acid (15.9-23.6%) are the main fatty acid components of all the species     

Early petroleum chemists and the beginnings of chromatography

Summary The activities of D. T. Day (1859–1915, J. E. Gilpin (1866–1924) and C. Engler (1842–1925) connected with the adsorptive filtration of petroleum oil samples are discussed. As indicated, their methodology can be considered as precursor of the chromatographic technique; however, it should not be envisaged as the beginnings of chromatography.     

Syntheses, Crystal Structures, and Conformations of 10,10-Spiro-Bilirubins

Summary. Crystal structure determinations of two novel bilirubin analogs with spirocyclohexyl and spirofluorenyl groups at C(10) are reported. Conformation-determining torsion angles and key hydrogen bond distances and angles are compared to those from molecular dynamics calculations, and to the corresponding data from X-ray determinations and molecular dynamics calculations of bilirubin. Like bilirubin, the component dipyrrinones of spirocyclohexyl and spirofluorenyl rubins are present in the bis-lactam form with (Z)-configuration double bonds at C(4) and C(15). Their crystal structures show considerable similarity to that of bilirubin: both pigments adopt a folded, intramolecularly hydrogen-bonded ridge-tile conformation stabilized by six hydrogen bonds. The interplanar angle of the spirocyclohexyl ridge-tile is nearly the same (94°) as that of bilirubin (95°), but the interplanar angle of the spirofluorenyl ridge-tile is noticeably smaller (84°). The hydrogen bond distances of both spiro-rubin crystal structures are generally longer by 0.1–0.2Å than those in bilirubin. Both new pigments exhibit excellent lipophilicity and, unlike bilirubin, are soluble in methanol.     

Fractional sublimation of some metal chelates of thenoyltrifluoroacetone

Studies on the fractional sublimation of various metal β-diketone chelates have been extended to include the chelates of thenoyltrifluoroacetone (TTA). Many of the common metal chelates were found to be stable, to sublime readily, and to form well-defined zones in the vacuum fractional sublimator. Of the 17 chelates reported only those of manganese (II) and iron(II) were not volatile. The chelates of UO₂(II), Zr(IV), Pb(II), and Cr(III) partially decomposed during sublimation and their recovery was incomplete. The recovery of the sublimed chelates of Ni(II), Mg(II), Al(III), Pd(II), Co(II), Cu(II). Fe(III), Tl(III), Zn(II) and Be(II) ranged from 87 to 100%, with most recoveries being quantitative. The sublimation recrystallization zone temperatures of the various chelates are compared to those of the metal acetylacetonates and the benzoyltrifluoroacetonates; in general, the metal chelates of TTA sublime more readily than those of benzoyltrifluoroacetone but are potentially less useful for fractional sublimation separations than the corresponding metal acetylacetonates. Even so, a quantitative separation of iron(III) from Ni(II), Al(III), Mn(II), and Fe(II) is proposed that depends upon the fractional sublimation of the TTA chelates.     

On the possibility of using model potentials for collision integral calculations of interest for planetary atmospheres

The interaction energy in systems (atom–atom, atom–ion and atom–molecule) involving open-shell species, predicted by a phenomenological method, is used for collision integral calculations. The results are compared with those obtained by different authors by using the complete set of quantum mechanical interaction potentials arizing from the electronic configurations of separate partners. A satisfactory agreement is achieved, implying that the effect of deep potential wells, present in some of the chemical potentials, is cancelled by the effect of strong repulsive potentials.     

Continuous flow structuring of anisotropic biopolymer particles

We review concepts and provide examples for the controlled structuring of biopolymer particles in hydrodynamic flow fields. The structuring concepts are grouped by the physical mechanisms governing drop deformation and shaping: (i) capillary structuring, (ii) shear and elongational structuring and (iii) confined flow methods. Non-spherical drops can be permanently structured if a solidification process, such as gelation or glass formation in the bulk or at the interface, is superimposed to the flow field. The physical and engineering properties of these processes critically depend on an elaborate balance between capillary phenomena, rheology, gel or glass formation kinetics, and bulk heat, mass and momentum transfer in multiphase fluids. This overview is motivated by the potential of non-spherical suspension particles, in particular those formed from ‘natural’ and ‘sustainable’ biopolymers, as rheology modifiers in food materials, consumer products, cosmetics or pharmaceuticals.     

Shape optimization of a cruciform geometry for biaxial testing of polymers

The presented literature review of cruciform shapes used for biaxial characterization of materials indicates that the majority of shapes can be divided into two large groups when the following selection criteria are taken into consideration: (i) the shape of the outer boundaries and (ii) the load capacity needed to achieve failure in the biaxial region. Manipulation of the outer shape boundaries appears to be essential to bundle the applied loads to the central zone where failure is intended to be built up. For each group, one particular cruciform design is reported whereby the outer boundaries are based on a single curved shape. Although the use of discontinuous double radii edges should be avoided according to earlier reports [1,2], it is shown here through the construction of an optimization algorithm, that the use of a single curve for the outer boundaries leads to strains in the arms that are strongly dependent on these single curved edges. Numerical simulations based on the finite element method as well as experiments performed on polymeric test pieces in combination with DIC measurements, show good agreement on this matter and demonstrate this sensitivity very clearly.     

Kinetic determination of microamounts of some sulphur-containing ligands

Some sulphur-containing ligands have been shown to inhibit the Hg(II)-catalysed substitution of p-nitrosodiphenylamine (p-NDA) for cyanide in hexacyanoferrate(II), by binding the mercury(II). This effect is used for determination of microamounts of cysteine, thioglycollic acid and thiosulphate. The reactions are followed spectrophotometrically at 640 nm (lambda(max) of [Fe(CN)(5).p-NDA](3-)). The determination range depends on the amount of mercury(II) added and the stability of the Hg(II)-ligand complex. Under specified conditions, the detection limits are: thioglycollic acid 1 x 10(-7)M, cysteine 1 x 10(-6)M and thiosulphate 4 x 10(-7)M.     

A question of policy: should tests for the self-disproportionation of enantiomers (SDE) be mandatory for reports involving scalemates?

The self-disproportionation of enantiomers (SDE) is a phenomenon that can lead to the perturbation of the enantiomeric excess (ee) in fractions obtained from a scalemic sample that has been subjected to a physical process. While fractional crystallization is widely appreciated as a means to effect enantiopurification, processes that are potentially able to give rise to the SDE phenomenon, notably chromatography, are greatly underappreciated in this regard. In this exposition we question if sufficient care is being taken by workers to avoid the erroneous reporting of stereochemical outcomes in asymmetric synthesis, natural products work, and other chiral-based areas of study due to ignorance of the SDE phenomenon and recommend the incorporation of SDE tests via sublimation and achiral chromatography as outlined herein to check for the occurrence of the SDE phenomenon in the applied methodology and routine experimental work.