Search results for "MIDI"

Photosensitization of DNA by β-carbolines: Kinetic analysis and photoproduct characterization

2012

β-Carbolines (βCs) are a group of alkaloids present in many plants and animals. It has been suggested that these alkaloids participate in a variety of significant photosensitized processes. Despite their well-established natural occurrence, the main biological role of these alkaloids and the mechanisms involved are, to date, poorly understood. In the present work, we examined the capability of three important βCs (norharmane, harmane and harmine) and two of its derivatives (N-methyl-norharmane and N-methyl-harmane) to induce DNA damage upon UV-A excitation, correlating the type and extent of the damage with the photophysical characteristics and DNA binding properties of the compounds. The r…

Nucleoside phosphotransferase of chick embryo

1979

This paper describes a purification procedure and some properties of a nonspecific nucleoside phosphotransferase of chick embryo, an activity which catalyzes the transfer of chick embryo, an activity which catalyzes the transfer of the phosphate ester from a deoxyribonucleotide or a pyrimidine ribonucleotide to a deoxyribonucleoside acceptor. The enzyme is very unstable to heat, dilution and dialysis and it is almost entirely inactivated by DEAE-cellulose chromatography or gel filtration. A marked enhancement in its stability is caused by numerous nucleotides. In these experiments at least 920-fold purification was obtained by using dTTP (50 microM) as nucleotide protector. The enzyme, puri…

Topology and Spin Polarization in Sheetlike Metal(II) Polymers: [ML2X2] (M ˭ Mn, Fe, Co or Ni, L = Pyrimidine or Pyrazine and X = NCS or NCO)

1999

The preparation and the structural and magnetic characterization of a series of sheetlike transition metal polymers of formula [ML2X2] [M ˭ Mn(II), Fe(II), Co(II) and Ni(II): L = pyrazine (pyz) and...

Heterogeneous oxidation of pyrimidine and alkyl thioethers in ionic liquids over mesoporous Ti or Ti/Ge catalysts.

2004

Heterogeneous catalytic oxidation of a series of thioethers (2-thiomethylpyrimidine, 2-thiomethyl-4,6-dimethyl-pyrimidine, 2-thiobenzylpyrimidine, 2-thiobenzyl-4,6-dimethylpyrimidine, thioanisole, and n-heptyl methyl sulfide) was performed in ionic liquids by using MCM-41 and UVM-type mesoporous catalysts containing Ti, or Ti and Ge. A range of triflate, tetrafluoroborate, trifluoroacetate, lactate and bis(trifluoromethanesulfonyl)-imide-based ionic liquids were used. The oxidations were carried out by using anhydrous hydrogen peroxide or the urea-hydrogen peroxide adduct and showed that ionic liquids are very effective solvents, achieving greater reactivity and selectivity than reactions p…

Temperature influence on moisture transfer through synthetic films

2000

Abstract Water transfer through films was investigated as a function of the temperature, the physical state of water and the relative humidity (RH) difference. The films were two synthetic packagings: a hydrophobic one, the polyethylene, a hydrophilic one, the cellophane. Some phenomena which could occur at low temperatures were discussed, such as polymer structure change due to mechanical relaxation or network plasticisation and modification of the penetrant diffusion at its melting temperature. But it seems that the comparison of water permeabilities (WPs) with temperature, especially at subzero temperatures, requires the correction of their calculation with the difference of water chemic…

A new equipment to measure the combined effect of humidity, temperature, mechanical stress and UV exposure on the creep behaviour of polymers

2008

To be able to study and predict the physical properties of a polymeric material under different environmental conditions is very important. Moisture, UV irradiation, thermal and mechanical stresses can dramatically change the characteristics of the material and hinder some specific applications. In this work, a new equipment able to perform creep tests under different environmental conditions (temperature, humidity, stress) is presented. Some preliminary results are also presented using a sample of polyamide 6. As this polymer is sensitive to all these variables, it is appropriate to verify the effectiveness of the new instrument.

Pyrrolo[3,4-e][1,2,3]triazolo[1,5-a]pyrimidine and pyrrolo[3,4-d] [1,2,3]triazolo[1,5-a]pyrimidine. New tricyclic ring systems of biological interest

2000

Derivatives of the new ring system pyrrolo[3,4-e][1,2,3] triazolo[1,5-a]pyrimidine 6 were prepared in high yields in one step by reaction of 3-azidopyrrole 3 and substituted acetonitriles. Compound 6b rearranged, upon heating in dimethyl sulfoxide in the presence of water, to pyrrolo[3,4-d][1,2,3]triazolo-[1,5-a]pyrimidine 7.

ChemInform Abstract: Pyrrolo[3,4-e][1,2,3]triazolo[1,5-a]pyrimidine and Pyrrolo[3,4-d][1,2,3]triazolo[1,5-a]pyrimidine. New Tricyclic Ring Systems of…

2001

Derivatives of the new ring system pyrrolo[3,4-e][1,2,3] triazolo[1,5-a]pyrimidine 6 were prepared in high yields in one step by reaction of 3-azidopyrrole 3 and substituted acetonitriles. Compound 6b rearranged, upon heating in dimethyl sulfoxide in the presence of water, to pyrrolo[3,4-d][1,2,3]triazolo-[1,5-a]pyrimidine 7.

Spin Polarization and Ferromagnetism in Two-Dimensional Sheetlike Cobalt(II) Polymers: [Co(L)2(NCS)2] (L=Pyrimidine or Pyrazine)

1998

Imidazolsynthesen, Mitt. Synthese α-substituierter 4(5)-Methoxymethyl-5(4)-methyl-imidazole

1977

Methoxymercurierung der α,β-ungesattigten Ketone 1 ergibt α-Acetoxymercuri-β-methoxy-ketone 2, die direkt zu α-Brom-β-methoxy-ketonen 3 bromo- demercuriert werden. Cyclisierung von 3 mit Formamidinacetat in flussigem Ammoniak fuhrt zu α-substituierten 4(5)-Methoxy-methyl-5(4)-methyl-imidazolen 4, deren Struktur 13C-NMR-spektroskopisch gesichert ist. Synthesis of α-Substituted 4(5)-Methoxymethyl-5(4)-methylimidazoles Methoxymercuration of the α,β-unsaturated ketones 1 produces the α-acetoxymercury-β-methoxyketones 2, which are bromo-demercurised without isolation to give the α-bromo-β-methoxyketones 3. Cyclisation of 3 with formamidine acetate in liquid ammonia leads to α-substituted 4(5)-me…