D.H. Christensen

The structure of thiophene

Abstract The microwave spectra of 2- C 13 -thiophene and of 3- C 13 -thiophene have been recorded and analyzed. In addition, three lines from the S 34 -thiophene were found and identified. Taken together with earlier published data for thiophene, thiophene-2 d , and thiophene-3 d , an unambiguous calculation of the (‘ r 8 ’-) structure of thiophene is now possible, the structural parameters being: (distances) CS = 1.714 A; CC = 1.370A; CC = 1.423 A; C(2)H(2) = 1.078 A; C(3)H(3) = 1.081 A; (angles) C(5)SC(2) = 92°10′; SC(2)C(3) = 111°28′; C(2)C(3)C(4) = 112°27′; SC(2)H(2) = 119°51′; C(4)C(3)H(3) = 124°16′.

The complete structure of furan

Abstract Microwave spectra of [2- 13 C] furan, [3- 13 C] furan, and [ 18 O] furan are reported. Moments of inertia of these species are combined with earlier data on furan and deuterated furans to give the r s -structure of furan. The final structure is: OC(2) = 1.362 A, C(2)C(3) = 1.361 A, C(3)C(4) = 1.431 A, C(2)H(2) = 1.075 A, C(3)H(3) = 1.077 A, C(5)OC(2) = 106°33′, OC(2)C(3) = 110°41′, C(2)C(3)C(4) = 106°3′, OC(2)H(2) = 115°55′, C(4)C(3)H(3) = 127°57′.

Molecular Structure of Propylene

The microwave spectra of seven isotopic species of propylene have been studied in order to obtain an accurate molecular structure. The complete rs (substitution) structure has been calculated. The more important parameters are: r(C=C)=1.336±0.004 A,r(C–C)=1.501±0.004 A, ≰CCC=124.3∘±0.3∘. The structure is compared with those of related molecules. It is concluded that no difference can be detected in the double‐bond lengths in ethylene, propylene, and the vinyl halides. The CC single‐bond length in propylene is indistinguishable from that in acetaldehyde and other acetyl compounds, and is 0.025 A shorter than the CC distance in saturated hydrocarbons. In the =CH2 group in propylene, the CH bond trans to the methyl group appears slightly shorter than the cis CH bond; a similar effect occurs in the vinyl halides.

Distinctive molecular abnormalities in benign and malignant skin lesions: studies by Raman spectroscopy.

Abstract— Near‐infrared Fourier transform Raman spectroscopy is an analytical, nondestructive technique that provides information about the molecular structure of the investigated sample. The molecular structure of proteins and lipids differs between neoplastic and normal tissues and therefore Raman spectroscopy has been considered promising for the diagnosis of cancer. We aimed to compare the molecular structure of normal skin, benign and malignant skin lesions by the near‐infrared Fourier transform Raman spectroscopy. Biopsies were obtained from the following skin lesions: skin tag, dermatofibroma, seborrhoeic keratosis, actinic keratosis, keratoacan‐thoma, basal cell carcinoma, squamous cell carcinoma, nevus intradermal, nevus compositus, dysplastic nevus and lentigo maligna. Control skin was harvested from the vicinity of these lesions. In the Raman spectra, the secondary structure of the proteins was reflected by the amide vibrations of peptide bonds. The principal lipid vibrations were twisting and wagging (CH2) and CH stretching vibrations. Histologically distinguishable lesions showed specific combinations of band changes indicating alterations in the protein conformation and in the molecular structure of the lipids. Histogenetically related lesions (actinic keratosis and sqamous cell carcinoma) produced similar but not identical patterns of spectral changes. Because the examined skin lesions produced reproducible and unique spectra, we suggest that Raman spectroscopy will be useful for diagnosis of skin lesions.

Benzene Ring Distortion by One Substituent. Microwave Determination of the Complete Structure of Benzonitrile

Microwave spectra of benzonitrile, C6H5CN, and 9 isotopic species are reported. Moments of inertia of these 10 molecules are combined to give the rs structure of benzonitrile. The final structure is: C(1)C(2) = 1.391 A, C(2)C(3) = 1.393 A, C(3)C(4) = 1.400 A, C(1)C(7) = 1.455 A, C≡N = 1.159 A, C(2)H(2) = 1.069 A, C(3)H(3) = 1.082 A, C(4)H(4) = 1.081 A, C(6)C(1)C(2) = 122.5°, C(1)C(2)C(3) = 118.45°, C(2)C(3)C(4) = 120.3°, C(3)C(4)C(5) = 120.0°, C(1)C(2)H(2) = 121.8°, C(4)C(3)H(3) = 119.9°.

Microwave Spectra of Thiophene, 2‐ and 3‐Monodeutero, 3,3′‐Dideutero, and Tetradeuterothiophene. Structure of the Thiophene Molecule

2‐ and 3‐monodeutero, 3,3′‐dideutero, and tetradeuterothiophene have been prepared and their microwave spectra recorded together with the microwave spectrum of ordinary thiophene (C4H4S). Lines originating from the 4% content of C4H4S34 and the 2% content of C3C13H4S in ordinary thiophene (both the 2‐ and the 3‐C13 species) were also identified. For all isotopic species rotational constants of high accuracy were obtained. The total material is sufficient for a complete determination of all the 8 geometrical parameters of thiophene.

An improved structure determination for vinyl fluoride

Abstract The previously published rotational constants of eight isotopic species of vinyl fluoride have been used to calculate an rs (substitution) structure for the molecule. The results are: r(CC) = 1.329 ± 0.006 A, r(CF) = 1.347 ± 0.009 A, ⦠ (FCC = 120.8° ± 0.3°, ∡FCH = 110° ± 1°, r(CH) = 1.082 ± 0.004 A; in the CH2 group : r(CH) = 1.077 ± 0.003 A and ∡HCC = 119.0° ± 0.3° for the CH bond trans to F; r(CH) = 1.087 ± 0.003 A and ∡HCC = 120.9° ± 0.3° for the CH bond cis to F.

Microwave Determination of the Structure of Fluorobenzene

3D‐, 4D‐, and 2,4,6 D3‐fluorobenzene have been prepared. Their microwave spectra have been recorded and analyzed. Values of their rotational constants together with known values of the rotational constants of ordinary fluorobenzene do not suffice for an unambiguous calculation of the 11 geometrical parameters of the molecule but by assistance from valence theory a small number of fairly probable models may be pointed out.

NIR-FT Raman spectroscopy as a diagnostic probe for mummified skin and nails

Abstract Raman spectroscopy is able to provide novel information non-destructively in the analysis of ancient skin tissue samples. The technique is well-suited to partially desiccated or wet samples of skin, which may have been subjected to varying degrees of degradation, depending on the burial environment. Suitable selection of wavelength of excitation and use of a Raman microscope offer a means of accessing information from small samples, which may be required for study afterwards using destructive analytical methods. From comparisons with the Raman spectra of healthy and diseased contemporary skin specimens, it is possible to discover whether the skin preservation has been natural or assisted by chemicals used in mummification processes. Such information is of importance in archaeological conservation and can shed light on historical practices. In this study will be presented the results from Raman spectroscopic analysis of the skin of the 5200-year-old “ice-man” of the Alps and, skin and nail samples from the mediaeval Qilakitsoq ice-mummies (500-year-old) and skin from the hot-desert Chiribaya Mummies (1000-year-old).

Plasticizers in P.V.C. and the Occurence of Hefatitis in A Haemodialysis Unit: A Preliminary Communication

In a four-year period three isolated cases of hepatitis were observed within a period of 2 months in a haemodialysis unit. The cases occurred in 3 patients during testing of new haemodialysis equipment. Liver biopsy in 2 patients showed non-specific hepatitis and changes as in “viral hepatitis” respectively. From the tested blood tubings, manufactured from polyvinylchloride (P.V.C.), diaethylphthalate was washed out in an amount of 10–20 mg per litre aqueous perfusate. From the tubings normally used in the department this compound was not released on perfusion, and the symptoms disappeared rapidly when treatment with the use of these tubings was resumed.