Determination of uranium and thorium in Eskişehir-Beylikahir ore samples by delayed neutron counting technique

The Eskiehir-Beylikahir district has the largest and richest thorium and rare earth elements deposits in Turkey. The uranium and thorium concentrations of samples taken from four different parts of this area have been determined by the delayed neutron counting technique. The results are compared with those of previous analyses by other techniques and found to be in good agreement.     

Gas chromatographic method for the determination of N-acetyl-S-(N-methylcarbamoyl)cysteine, a metabolite of N,N-dimethylformamide and N-methylformamide, in human urine

A simple method has been developed for the determination of N-acetyl-S-(N-methylcarbamoyl)cysteine in human urine. Treatment of a urine sample (1 ml) with ethanol (2 ml) and potassium carbonate (1.5 g) produces ethyl N-methylcarbamate, which is extracted into ethanol and measured by packed column gas chromatography with nitrogen-sensitive detection. The limit of quantitation in human urine is 1 microgram/ml and the between-sample coefficient of variation is 5-11%. Simultaneously, N,N-dimethylformamide, N-methylformamide and formamide can also be determined.     

Sulfate Ions in Titania Polymorphs

Sol-gel titania was sulfated by using sulfuric acid as hydrolysis catalyst, or by impregnating with ammonium sulfate fresh samples prepared with nitric acid or ammonium hydroxide as hydrolysis catalyst. Samples were characterized with X-ray powder diffraction, infrared spectroscopy, thermogravimetry and atomic absorption spectroscopy. Sulfate ions were found anchored to brookite and anatase phases, because they have short O—O atomic bond lengths slightly larger than the largest O—O bond length of sulfate ion. Since the shortest O—O atomic bond in anatase is smaller than the one in brookite, the sulfate ions are then less deformed when they are anchored to anatase, and consequently more stable. Therefore when the sample temperature is raised, the brookite with sulfate ions was transformed mainly to anatase and not into rutile, which is the most probably transformation when these ions are not involved. Sulfate ions also hindered anatase and brookite crystallite growing and stabilized the crystalline structure of anatase. When the sulfate ions are lost the crystalline anatase phase is transformed into rutile, leaving a large number of vacancies that favored atom diffusion and consequently the growing of rutile crystallites. The crystalline evolution of the samples as a function of the annealing temperature is almost independent of the sulfating method.     

Calorimetric study of the glassy state XII. Plural glass-transition phenomena of ethanol

Ethanol was found to give a metastable crystalline phase (crystal-II) when the liquid was cooled at a moderate rate. Glassy states of liquid and of newly found crystal-II were obtained in the calorimeter cell by controlling the cooling rate of the liquid. The heat capacities of these phases as well as that of the stable crystal-I were measured by an adiabatic calorimeter in the temperature range between 14 and 300 K. The glass transition temperature T_g, the heat-capacity jump at T_g, and the residual entropy were found to be 97 K, 35.3 J K^?1 mol^?1, and 8.93 J K^?1 mol^?1 for the glassy liquid, and 97 K, 22.8 J K^?1 mol^?1, and 4.24 J K^?1 mol^?1 for the glassy crystal-II, respectively. The values for the residual entropy are referred to the third-law entropy for crystal-I.The heat capacities reported previously for the supercooled liquid by Gibson et al. and by Parks and Kelley agree well with those for the metastable crystal-II. Those of the supercooled liquid connect smoothly with those obtained for the liquid above the melting temperature. Thus, ethanol is found to be another example of a low-molecular-weight compound which shows multiple glass-transition phenomena.     

Selective palladium-catalyzed arylation(s) of benzaldehyde derivatives by N-heterocarbene ligands

The 2- or 2,6-position(s) of aromatic aldehydes were directly and selectively arylated with aryl chlorides or bromides in the presence of a catalytic system prepared in situ from Pd(OAc)₂, imidazolinium chlorides (1-5) and Cs₂CO₃.     

Preparation and characterization of Co(II), Ni(II) and Cu(II) complexes of a ligand containing 1,3,4-thiadiazole groups

(1R,2R)-1,2-bis-(5-amino-1,3,4-thiadiazole-2-yl)ethane-1,2-diol (L) has been prepared by the reaction of thiosemicarbazide with (2R,3R)-(+)-tartaric acid (I) and phosphorous oxychloride, and its complexes with Co(II), Ni(II) and Cu(II) have been obtained. The structures of the ligand and its complexes have been established by i. r., ¹H- and ¹³C-n.m.r. spectra, u.v.–vis–nir spectroscopy, elemental analyses, T.g.-D.t.a. and magnetic susceptibility measurements.     

Phenolic compounds from the aerial parts of Clematis viticella L. and their in vitro anti-inflammatory activities*

Phytochemical investigations on the EtOH extract of Clematis viticella led to the isolation of six flavonoid glycosides, isoorientin (1), isoorientin 3′-O-methyl ether (2), quercetin 7-O-α-L-rhamnopyranoside (3), quercetin 3,7-di-O-α-L-rhamnopyranoside (4), manghaslin (5) and chrysoeriol 7-O-β-D-glucopyranoside (6), one phenylethanol derivative, hydroxytyrosol (7), along with three phenolic acids, caffeic acid (8), (E)-p-coumaric acid (9) and p-hydroxybenzoic acid (10). The structures of the isolates were elucidated on the basis of NMR and HR-MS data. All compounds were isolated from C. viticella for the first time. Compounds 7 and 8 showed significant anti-inflammatory activity at 100 μM by reducing the release of NO in LPS-stimulated macrophages comparable to positive control indomethacin. Compounds 3 and 7 exhibited anti-inflammatory activity through lowering the levels of TNF-α while 1, 3 and 5 decreased the levels of neopterin better than the positive controls.     

Solid-state vibrational spectroscopy: Part VI. An infrared and raman spectroscopic study of transition metal(II)4-methylpyridine complexes

Infrared (4000–200 cm^?1) and Raman (3500–300 cm^?1 ) spectra are reported for metal(II) halide and thiocyanate 4-methylpyridine complexes of the following stoichiometries: (MX₂(4-Mepy)₂) {M = Mn, Co, Cu or Zn, X = Cl or Br; M = Mn, Ni or Zn, X = NCS}; (MX₂(4-Mepy)₄) {M = Mn, Fe, Co or Ni, X = Cl or Br; M = Mn, Fe, Co, W or Cu, X = NCS}. For a given series of isomorphous complexes there is a correlation between the sum of the differences between the liquid and ligand values of the ν₁, ν₂, ν₃, ν₄, ν₅, ν₆, ν₇, ν₈, ν₉, ν₁₀, ν₁₂, ν₁₃ and ν₁₄ modes of 4-methylpyridine and the strength of the metal-nitrogen bond. Comparison of the shift values of pyridine and 4-methylpyridine complexes supports the suggestion that, unlike the situation in the pyridine complexes, back-donation from the metal to the ligand is unimportant in the 4-methylpyridine complexes.     

Thermal characterization of benzylcellulose derivatives prepared from bleached pinus kraft pulp

The thermal characterization (DSC and TG) of benzylcellulose derivatives prepared from the benzylation of bleached Pinus Kraft pulp is described in this paper. The objective of this study was to examine the changes in glass transition temperature (T _g) and the thermal stability of the benzylated product as a function of the benzylation extent (degree of substitution). The DSC analysis showed that the benzylcelluloses can display glass transition temperature at two different regions and that thermal stability is slightly higher than that of the parent cellulose. This revised version was published online in August 2006 with corrections to the Cover Date.