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1H nuclear magnetic resonance characterization of Portland cement: molecular diffusion of water studied by spin relaxation and relaxation time-weighted imaging (1998)

Wang, Pu Sen ; Ferguson, M. M ; Eng, G ; [et al.]

Springer

Journal of materials science 33 (1998), S. 3065-3071

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ISSN: 1573-4803

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Water molecular dynamics in a hardened Portland cement were characterized by proton Fourier transform nuclear magnetic resonance (NMR) at 400 MHz. Three different types of water molecule (physically bound, chemically bound and porous trapped) were observed. When the hardened cement sample was heated at 105 °C, the physically bound water diffused out of the sample as a function of the heating time while the chemically bound water remained in a stable form. A trace amount of the porously trapped water was also detected to remain in the cavities of the hardened cement even after heating for up to 20 h at this temperature. The loss of the physically bound water proved to be a diffusion-controlled process as evidenced from the NMR data and from a gravimetric technique. A Pake doublet was observed in the NMR spectra. This is a result of the oscillation of the water molecules with hindered molecular motions due to their entrapment in the cement pores. Soaking the dried samples in water resulted in the diffusion of water back into the hardened cement as physically bound water. Nuclear spin–spin relaxation time, T2-weighted imaging showed that the distribution of the physically bound water inside the cylindrical sample formed a doughnut shape after overnight soaking. The residual air in the cement pores may have slowed down the diffusion rate of the water molecules back into the dried cement. © 1998 Kluwer Academic Publishers

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004331403418

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Synthesis, characteristic spectral studies and in vitro antimicrobial and antitumour activities of organotin(IV) complexes of Schiff bases derived from amino-acids (1997)

Nath, Mala ; Yadav, Rakesh ; Gielen, Marcel ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Applied Organometallic Chemistry 11 (1997), S. 727-736

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ISSN: 0268-2605

Keywords: organotin(IV) ; Schiff base ; amino-acid ; antimicrobial activity ; antitumour activity ; Chemistry ; Industrial Chemistry and Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Equimolar reactions of dibutyltin(IV) oxide with Schiff bases derived from amino-acids led to the formation of a new series of dibutyltin(IV) complexes of general formula, Bu2SnL [L=dianion of tridentate Schiff bases derived from the condensation of 2-hydroxy-1-naphthaldehyde or acetyl acetone with glycine (L-1), L-β-alanine (L-2), DL-valine (L-3), DL-4-aminobutyric acid (L-4), L-methionine (L-5), L-leucine (L-6) and phenylglycine (L-7)]. An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analyses, conductance measurements and electronic, IR, multinuclear magnetic resonance (1H, 13C and 117Sn) and 119Sn Mössbauer spectral studies. The complexes have been tested against various bacteria [Streptococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus penicillin resistance (2500 units)] and fungi (Candida albicans, Cryptococcus neoformans, Sporotrichum schenckii,Trichophyton mentagrophytes and Aspergillus fumigatus). All the complexes showed moderate activity. The cytotoxicity of a few compounds has been screened in vitro against seven human tumour cell lines, viz. MCF-7, EVSA-T, WiDr, IGROV, M19 MEL, A498 and H226. The activities found experimentally were better than those obtained for cisplatin and carboplatin © 1997 John Wiley & Sons, Ltd.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

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Fungicidal Activity of Some Organotin Compounds against Ceratocystis ulmi (1996)

Eng, G. ; Whalen, D. ; Zhang, Y. Z. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Applied Organometallic Chemistry 10 (1996), S. 501-503

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ISSN: 0268-2605

Keywords: Ceratocystis ulmi ; dialkyltin ; Dutch elm disease ; fungicide ; organotin ; triphenyltin ; Chemistry ; Industrial Chemistry and Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Three series of organotin compounds were screened in vitro against Ceratocystis ulmi, the causative agent of Dutch elm disease. The series that were most active against this deadly fungus were those that contained the triphenyltin moiety. In addition, the fungicidal activity of the triphenyltin compounds were found to be independent of the anionic group attached to the tin atom. However, there was a marked increase in the activity of the triphenyltins when a biologically active group which did not dissociate upon dissolution was incorporated into the overall molecule.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

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