Contents and localization of heavy metals in human placentae

The placenta was used as an exposure index for the risk evaluation of prenatal fetal chemical exposure. Full-term placenta samples collected at maternity hospitals in 4 regions of different environmental pollutants and traffic density were examined for lead and cadmium contents using atomic absorption spectrometry (AAS). The results showed similar lead contents in placental samples from all selected regions, except for a small town with a lower traffic density. The findings may implicate traffic-related environmental lead pollution, rather than industrial sources. The highest concentration of cadmium was shown to be in the samples collected from the region with the highest proportion of smoking mothers (including passive smoking). Simultaneously, the placental samples were processed histochemically to determine the location of lead in the placental tissue (using light microscopy). The degree of placental metal contamination was done semiquantitatively, and the difference between the rural and industrial region was statistically compared. Parallel quantitative AAS analyses and semiquantitative histochemical lead analyses of human placental samples revealed analogous results regarding the level of placental contamination with metals. Received: 30 June 1997 / Revised: 21 December 1997 / Accepted: 30 December 1997     

Sorption properties of technical lignins. III. IR-spectral investigation of the sorption capacity of technical lignins and their derivatives in relation to bile acids

It has been established by IR-spectral investigations that the sorption of bile acids by technical lignins takes place through the formation of hydrogen bonds between the functional groups of thelignins and the bile acids, the form of these bonds being determined by nature of the lignins and acids concerned. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (371) 240 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 545–547, July–August, 1998.     

Complexation of Ni (II) and Zn(II) ions by 3-(1-naphthyI)-2-mercaptopropenoic acid

The complexation equilibria between Ni(II) and Zn(II) metal ions with 3-(1-naphthyl)-2-mercaptopropenoic acid (H₂NMP) were studied by glass electrode potentiometry, at 25 °C and 1.0 mol·dm^–3 in NaClO₄ as constant ionic medium in 50% (v/v) water-ethanol solutions. Formation constants for the complexes Ni(NMP), Ni(NMP) ₂ ^2– , Zn(NMP) and Zn(NMP) ₂ ^2– , refined by the MINIGLASS program, are reported.     

The structure of the 1-1-difluoroethylene radical anion and the factors determining the hyperfine interaction with 19F

A structure with a pyramidal -CF₂ group is shown to desribe satisfactorily hyperfine interactions in CH₂CF_$\text{2}$ radical anions within the framework of the INDO method. The factors responsible for the substantial difference in the degree of spin density delocalization on F in CH₂CF_$\text{2}$ and C₂F_$\text{4}$ are analyzed.     

Molecular orbital study of gas phase basicities of carbofunctional derivatives of group IVB elements; stereochemical control

The gas phase basicities of a series of carbofunctional derivatives H₃M(CH₂)_nX (M = C, Si, Ge; X = NH₂, OH, F; n = 1–3) were investigated by the semiempirical CNDO/2 method. The calculations indicate that the electronic effects of silyl- and germyl-substituents differ greatly from the effect of simple alkyls. Moreover, in contrast to simple carbon derivatives, the overall nature of the electronic effects of siliyl- and germyl-substituents is crucially influenced by the molecular conformation.     

Nachweis von Oxoverbindungen. IV

Zusammenfassung Enolisierende Oxoverbindungen, die eine - CH₂-CO- oder eine- CO-NH-NH-Gruppe enthalten, geben mit Diazoniumsalz eine Farbreaktion. Formaldehyd, Benzaldehyd, Nitrobenzaldehyde, Benzoin, Benzophenon usw. reagieren dabei nicht. 1,3-Diketone geben mit diazotiertem p-Nitroanilin zweierlei Färbungen, bei geringer Diazoniumsalzkonzentration eine rote, bei großem Überschuß eine blaue oder grüne Färbung. Die Reaktionsgeschwindigkeit ändert sich auch nach der Art des Diazoniumsalzes. Mit dieser Methode wurden selektive Nachweise für Oxoverbindungen ausgearbeitet. Acetonspuren können in Äthanol bzw. in Wasser oder in Methyläthylketon mit diazotiertem Anilin, 10^–3 % Acetessigsäureäthylester in Äthylacetat mit diazotiertem p-Phenetidin, 10^–5 % Acetylaceton in Aceton mit diazotiertem p-Nitroanilin, außerdem Acetaldehyd neben Formaldehyd, Acetylphenylhydrazin neben Acetanilid, mbzw. o- neben p-Nitroanilin nachgewiesen werden. Nach dem Absorptionsspektrum erwies sich das Reaktionsprodukt von Aceton mit diazotiertem p-Nitroanilin als eine Azoverbindung.

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Detection of Oxocompounds. IV

Summary Enolizing oxo-compounds, that contain a -CH₂-CO- or a -CO-NH-NH-group, yield a color reaction with diazonium salt. Formaldehyde, benzaldehyde, nitrobenzaldehyde, benzoin, benzophenone etc. however do not show this reaction. 1,3-diketones yield two kinds of color reactions with diazotizedp-nitraniline; a slight diazonium salt concentration yields a red coloration, while a large excess gives a blue or green coloration. Selective detections for oxo-compounds were developed with this method. Traces of acetone may be detected in ethanol or water or in methylethyl ketone by means of diazotized aniline, 10^–3% of acetoacetic ester can be detected in ethyl acetate by means of diazotizedp-phenetidine, 10^–5% acetylacetone in aldehyde, acetylphenylhydrazine in the presence of acetanilide,m- oro- in the presence ofp-nitraniline. Judging from the absorption spectrum, the reaction product from acetone and diazotizedp-nitraniline is an azo compound.

     

2-arylfuro [2,3-b] quinoxalines

2-Arylfuro[2,3-b]quinoxalines were obtained by cyclization of 2-phenacyl-3-quinoxalones in the presence of polyphosphoric acid or a mixture of phosphorus oxychloride and phosphorus pentachloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–260, February, 1973.     

Solution properties of poly p-isopropyl α-methylstyrene

Two series (S and F) of poly p-isopropyl α-methylstyrene were characterized by viscometry, light scattering (LS), osmometry and gel permeation chromatography (GPC). S-samples were prepared by bulk anionic polymerization whereas F-samples were obtained on fractionation by preparative GPC of a polymer also prepared in bulk but with a different initiator. The K parameter in the Mark-Houwink relation was 5.55 × 10^?4 for series-S and 4.50 × 10^?4 for series-F, whereas the exponent a was 0.55 for both series. The Mark-Houwink equations for series-S and -F hold good at 25 and 30° for both toluene and tetrahydrofuran as solvents and have been corrected for polydispersity. The chain dimensions obtained with LS were much higher than those computed from the viscosity data indicating that the hydrodynamic theories in their present state should not be used for the calculation of chain dimensions. The deviations from the GPC universal calibration curve of polystyrene observed with some samples were attributed to structural differences among the polymers and to their high polydispersity.     

Prompt gamma activation analysis using a chopped neutron beam

A beam chopper has been developed at the cold neutron PGAA facility of the Budapest Research Reactor. In the open phase of the chopper the usual prompt gamma-spectrum is recorded, while in the decay phase short-lived decay lines can be collected with good counting statistics on an extremely low baseline. A series of elements has been measured with the chopped beam technique to assess the capabilities of the new technique. An archaeological sample was also examined, to demonstrate how spectral interferences can be resolved.     

Me2ESiMe3 (E = As,N, P) Compounds—Efficient Reagents for Replacement of the Fluorine Atom by Me2E Group in the Complex [(η6-1-F-3,5-Me2C6H3)(η5-C5EtMe4)Rh](CF3SO3)2 >

Russian Journal of Organic Chemistry -