Electrostatic Accumulation Furnace for Electrothermal Atomic Spectrometry (E. A. F. E. A. S.)

Abstract

A new technique is described for rapid elemental analysis of atmospheric particulates. The basic principle is direct deposition of atmospheric particulate matter in a furnace for electrothermal atomization and analysis by atomic absorption spectrometry. A prototype instrument has been tested by analyzing the lead content in the laboratory atmosphere.     

Eriochrome blue S.E. as indicator in chelatometric titrations

Summary The use of eriochrome blue S. E. as a metal indicator for the EDTA titrations of zinc, cadmium, magnesium, lead, nickel and manganese is described. Spot tests for the determination of the sensitivity limits of dectection of the end points are given.     

E.S.R. investigation of helix inversion in induced cholesteric phases

The phenomenon of a reversible helix inversion in induced cholesteric mesophases caused by variation of the temperature has been investigated by E.S.R. spectroscopy using the nitroxide radical tempone as spin probe. Chiral esters of optically active (R)-(+)-2,2'-dihydroxy-1,1'-binaphthyl were added as dopants to the nematic mixture RO-TN 404. The inversion temperatures and the handedness of the helices were determined. In addition to the distortion parameter which is a measure of the helix pitch, order parameters and rotational correlation times of the spin probe were obtained from line-shape analyses.     

E.S.R. of hydrazoxyl radicals: Evidence for conformational isomers.

Thermolysis of azocarboxylates has been investigated by e.s.r. Experimental evidence for the existence of conformational isomerism in acylnitroxides has been obtained.     

两种细菌的毛细管电泳分离及其与药物相互作用的研究

通过对大肠杆菌与金黄色葡萄球菌的毛细管电泳行为的研究,包括对细菌样品预处理、缓冲液、检测波长以及聚合物添加剂对分离度的改进等的考察,在优化的实验条件下,实现了大肠杆菌与金黄色葡萄球菌的快速分离,从而建立一种新的细菌辅助识别与定性的补充方法。将抗菌药物阿奇霉素与金黄色葡萄球菌混合培育,发现由于阿奇霉素抑制细菌表面蛋白合成,造成与金黄色葡萄球菌作用后,细菌表面电荷密度降低,表现为阿奇霉素对金黄色葡萄球菌的电泳淌度的影响,而且培育时间与金黄色葡萄球菌的淌度线性相关。     

Post-gamma-irradiation grafting of polypropylene. Part II. Butadiene: E.S.R. experiments

ESR spectra of gamma irradiated annealed and quenched forms of polypropylene film have been studied at the temperatures used for post-irradiation grafting experiments with butadiene, described in Part I. On warming from low temperature there is radical loss by termination and some radical transformation to radicals with optimum stability in annealed polypropylene at approximately 45°C. These radicals, which may be allyl type, are sited at the crystal faces, and decay more rapidly at higher temperatures in annealed polypropylene; in quenced polypropylene their concentration never exceeds one third the optimum observed in annealed polypropylene. Correlation with the grafting experiments suggests that allyl radicals are important for long-term grafting. Effects on the ESR spectrum of adding butadiene to the system show that in the long-term butadiene adds exclusively to the allyl radicals and that alkyl radicals still present at that stage are precursors to the allyl radicals. They do not react directly with butadiene presumably because they are sited in the inaccessible crystal core. Experiments at lower temperature show that butadiene does react with alkyl radicals in accessible regions.     

An E.S.R. study of spin-trapping by azodicarboxylates to give hydrazyl radicals

Addition of photochemically- or thermally-generated radicals (X·) to dialkyl azodicarboxylates gives hydrazyl radicals [RCO₂(X)N·CO₂R] which are readily detected by e.s.r. spectroscopy.     

An E.S.R. study of radicals obtained by the oxidation of 3,6-dihydroxypyridazines

One electron oxidation of the plant growth substance 3,6-dihydroxypyridazine (maleic hydrazide) gives a cyclic α-carbonylhydrazyl, the e.s.r. parameters of which are assigned by comparison with five related radicals.     

E.S.R. and optical study of VO2+ in lithium zinc-phosphate glasses

The E.S.R. and optical spectra of glasses of basic composition 30% Li₂ O-30% ZnO-40% P₂ O₅ doped with vanadium have been studied.The partial substitution of ZnO with Al₂O₃ and PbO has a great effect on the chemical durability of the glasses but does not affect their magnetic and optical properties.The E.S.R. and optical data suggest that the dxy orbital of the umpaired spin of the V(IV) specie is not bonded with the π orbitals of the in plane ligands while there is a strong σ bonding with the same ligands. The bonding between the vanadium and the vanadyl oxygen is only slightly covalent. The E.S.R. spectra show a large reduction of the line-width when the concentration of the V₂O₅ goes from 1% to 0.1% showing that the dipolar broadening gives the larger contribution to the E.S.R. line-width.     

Inhaltsstoffe des Osmanthus-Absolues 6. Mitteilung. (7S, 10S, 5E)- und (7R, 10S, 5E)-2,6,10-Trimethyl-7,10-epoxy-2,5,11-dodecatrien

Constituents of Osmanthus Absolute, 6th Communication. (7 S , 10 S , 5 E ) - and (7 R , 10 S , 5 E )-2,6,10-Trimethyl-7,10-epoxy-2,5,11-dodecatriene Two novel sesquiterpenoid oxides 1a and 1b from Osmanthus absolute have been identified. Their structural proof is based on pectral data and synthesis starting from the known methyl [5-methyl-5-vinyl-tetrahydrofur-1-yl] ketones ( 4a and 4b , respectively), whose configuration is well established. The thus obtained compounds 1a / 1b identical with the natural products, were accompanied by their corresponding 6-methylidene isomers 3a and 3b which could not be detected in the natural substrate.     

Structure-activity relationships of galabioside derivatives as inhibitors of E. coli and S. suis adhesins: nanomolar inhibitors of S. suis adhesins

Four collections of Gal alpha1-4Gal derivatives were synthesised and evaluated as inhibitors of the PapG class II adhesin of uropathogenic Escherichia coli and of the P(N) and P(O) adhesins of Streptococcus suis strains. Galabiosides carrying aromatic structures at C1, methoxyphenyl O-galabiosides in particular, were identified as potent inhibitors of the PapG adhesin. Phenylurea derivatisation at C3' and methoxymethylation at O2' of galabiose provided inhibitors of the S. suis strains type P(N) adhesin with remarkably high affinities (30 and 50 nM, respectively). In addition, quantitative structure-activity relationship models for E. coli PapG adhesin and S. suis adhesin type P(O) were developed using multivariate data analysis. The inhibitory lead structures constitute an advancement towards high-affinity inhibitors as potential anti-adhesion therapeutic agents targeting bacterial infections.     

Unraveling the protein targets of vancomycin in living S. aureus and E. faecalis cells

Vancomycin is a potent glycopeptide antibiotic that has evolved to specifically bind to the D-Ala-D-Ala dipeptide termini of nascent peptidoglycans. Although this mode of action is well established, several studies indicate that vancomycin and analogues exploit noncanonical target sites. In order to address all vancomycin targets in clinically relevant Staphylococcus aureus and Enterococcus faecalis strains we developed a series of small-molecule photoaffinity probes based on vancomycin. Proteomic profiling revealed the specific labeling of two previously unknown vancomycin targets that are likely to contribute to its antibiotic activity. The specific inhibition of the major staphylococcal autolysin Atl confirms previous observations that vancomycin alters S. aureus cell morphology by interaction with the autolytic machinery. Moreover, in E. faecalis the vancomycin photoprobe specifically binds to an ABC transporter protein, which likely impedes the uptake of essential nutrients such as sugars and peptides. The labeling of these two prominent membrane targets in living cells reveals a thus far unexplored mode of vancomycin binding and inhibition that could allow a rational design of variants with improved activity.     

The E.S.R. Spectrum of the tetra(1-adamantyl)cyclobutadiene radical cation

A revised interpretation is proposed for the ¹H and ¹³C hyperfine coupling in the e.s.r. spectrum of the tetra-1-adamantylcyclobutadiene radical cation, and assumes that free rotation occurs about the 1-adamantyl bond.