Heat Capacities of Three Isomeric Chlorobenzenes and of Three Isomeric Chlorophenols

Isobaric heat capacities C _p in the liquid and in the solid phase of 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2,4-trichlorobenzene, 3-chlorophenol and 4-chlorophenol and in the liquid phase of 2-chlorophenol were measured by commercial Setaram heat conduction and power compensated calorimeters. Results obtained cover the following temperature range (depending on the compound and state of aggregation): 1,2-dichlorobenzene 208 to 323 K,1,3-dichlorobenzene 183 to 323 K, 1,2,4-trichlorobenzene 133 to 323 K, 2-chlorophenol from293 to 353 K, 3-chlorophenol and 4-chlorophenol from 133 to 353 K. The heat capacity data obtained in this work were merged with available experimental data from literature, critically assessed and sets of recommended data were developed by correlating selected data as a function of temperature. Temperature and enthalpy of fusion of two isomeric chlorophenols and of 1,2,4-trichlorobenzene were also determined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Utilization of radiochemical and mass-spectrometric analysis of the spent fuel of the A-1 power plant for non-destructive burn-up determination

During the burning-up fuel in a nuclear reactor, changes in the isotopic composition of the fuel as well as in the reactor power generation take place. To explain these effects, destructive radiochemical analyses of the spent fuel were carried out. The results obtained have been used for the calibration of non-destructive burn-up determination and for the evaluation of simple computer codes. The main results of the codes as well as the methods applied for the separation of radionuclides studied are presented.     

Osmylated macroporous resins: safe,highly efficient and recyclable catalysts for asymmetric aminohydroxylation of olefins

Osmylated macroporous resins displayed excellent catalytic performances in the asymmetric aminohydroxylation of olefins and, moreover, these resins were easily recovered and reused without any significant decrease in catalytic efficiencies.     

32P-postlabelling and mass spectrometric methods for analysis of bulky, polyaromatic carcinogen-DNA adducts in humans.

There has been significant recent progress toward the development of human carcinogen-DNA adduct biomonitoring methods. 32P-Postlabelling is a technique which has found wide application in human studies. 32P-Postlabelling involves enzymatic preparation and labelling of DNA samples, followed by chromatographic separation of carcinogen-nucleotide adducts from unadducted nucleotides. Thin-layer ion-exchange and high-performance liquid chromatography (HPLC) have been utilized. This paper critically reviews 32P-postlabelling methods for analysis of bulky, polyaromatic carcinogen-DNA adducts and details a strategy to optimize this technique for monitoring human samples. Development of a human carcinogen biomonitoring method requires that the biomarker meet certain criteria: that the biomarker be responsive to exposures known to increase human cancer risk, to reductions in those exposures, and to the influence of metabolic differences. In addition, reliable samples must be available by non-invasive means. The ability of 32P-postlabelling to meet these criteria is traced in the literature and discussed. Identification of specific carcinogen-DNA adducts is a difficult task due to the low (femtomole) levels in human target tissues. Because co-chromatography in thin-layer chromatography (TLC) is generally not considered to be proof of chemical identity, both synchronous fluorescence and HPLC in conjunction with 32P-postlabelling and TLC are used to confirm the identity of specific carcinogen-DNA adducts in human samples. Mass spectrometry is a highly specific method, the sensitivity of which has been improved to the point which may allow its use to confirm the identity of carcinogen-DNA adducts isolated by 32P-postlabelling and other methods. The literature relating to the use of mass spectral techniques in carcinogen-DNA adduct analysis is reviewed.     

Investigation of sulfhydryl groups in cabbage phospholipase D by combination of derivatization methods and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

All eight cysteine residues in 92 kDa cabbage phospholipase D (PLD), deduced from the cDNA sequence, were shown to have free sulfhydryl groups by analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) of tryptic peptides of PLD derivatized with p-chloromercurybenzoate, iodoacetic acid, and N-ethylmaleimide, as well as of underivatized PLD. Assignment of sulfhydryl groups by any one method was not conclusive. However, complementary information derived from tryptic peptides derivatized with different reagents made full assignment of sulfhydryl groups possible.     

Coordination chemistry of polyoxomolybdates: The versatile behavior of amidoximes

The reactions of 2-thienylamidoxime and 2-thienylmethylamidoxime with [MoO₂(acae)₂] or x-(NBu₄ [Mo₈O₂₆]. in alcohols or acetonitrile, yield a number of compounds with different nuclearities and various molybdenum cores, such as the compact {Mo₄O₁₀(OMe)₂}²⁺ the cyclic {Mo₄O₁₂}, and the open {Mo₁₁On_211-1}²⁺ (n= 2 or 4) cores. Addition of NH₂OH to the reaction mixtures results in the formation of nitrosyl complexes containing either the Mo(NO)³ or the Mo(NO) ₂ ² units. The amidoxime component may be present either as RC(NH₂)NHO. RC(NHi2), RC(NH)NHO or RC(NH)NO²: ligands, or as hydrogen-bonded RC(NH₂)NOH molecules. The crystal structures of [MoO(acac)RIC'(NH₂)NO] {R^JC(NH)NO}](1), [Mo(NO)(acae)₂ {R^IC(NH₂)NO}] (4), (NBu₄)₂[Mo₄O₁₀(OMe)₂{R^IC(NH) NO}₂] (12a),(NBu₄)₂(H₃O)[Mo₅O₁₃(OMe)₄(NO)].2R¹C(NH₂)NOH(13b) and [R¹C(NH₂)₂)]₃[Mo₅O₁₃(OEt)₄(NO)] (14) (R¹=2-thienyl) are reported. The cryslallographic data for these compounds are as follows:1, mono-clinic. P2₁ a.a=24.547(4)A. b=8.188(4)A. c=9.607(3)A, ß=96.18(3)^c, R=0.046. R₁₀=0.050: 4. monoclinic, P2₁c.a=8.265(2)A, b=9.381(2)A,_c=24.770(4)A, c = 24.7701(4) A, ß=93.99(2). R=0.039. R=0.042;12a, monoclinic, C2/c, a= 19.570(5)A. b=16.883(4)A, c = 19.82(l)A. ß= 114.36(5)°, R=0.064,R.=0.074;13b monoclinic;. P2₁ c.a=18.197(5)A, b=15.857(14) A, c = 23.075(17) A, =93.20(3). R=O.050. R_w=0.057;14, trictinic PI, a = 9.871(3),b= 14.138(3).c= 14.781(8)A. =92.67(2)^c =99.36(1)° =90.52(2)°. R = 0.044. R_w = 0.049. Particular attention is focused on the various coordination modes that the different ligand forms adopt: µ- O, ²N,O, ₂N',O, µ-N: ²O. and ₃- N:N:₂O.     

Cytochrome C-dependent Fas-independent apoptotic pathway in HeLa cells induced by delta12-prostaglandin J2

Cyclopentenone prostaglandins (PGs) have antiproliferative activity on various tumor cell growth in vitro. Particularly, 9-deoxy-delta(9,12)-13,14-dihydro PGD(2) (delta(12)-PGJ(2)) was reported for its antineoplastic and apoptotic effects on various cancer cells, but its mechanism inducing apoptosis is still not clear. In this study, we have characterized apoptosis induced by delta(12)-PGJ(2) in HeLa cells. Treatment of delta(12)-PGJ(2) induced apoptosis as indicated by DNA fragmentation, chromatin condensation, and formation of apoptotic body. We also observed release of cytochrome c from mitochondria and activation of caspase cascade including caspase-3, -8, and -9. And the pan-caspase inhibitor z-Val-Ala-Asp (OMe) fluoromethyl-ketone (z-VAD-fmk) and Q-Val-Asp (OMe)-CH(2)-OPH (Q-VD (OMe)-OPH) prevented cell death induced by delta(12)-PGJ(2) showing participation of caspases in this process. However, protein expression level of Bcl-2 family was not altered by delta(12)-PGJ(2), seems to have no effect on HeLa cell apoptosis. And ZB4, an antagonistic Fas-antibody, exerted no effect on the activation of caspase 8 indicating that Fas receptor-ligand interaction was not involved in this pathway. Treatment of delta(12)-PGJ(2) also leads to suppression of nuclear factor kappaB (NF-kappaB) as indicated by nuclear translocation of p65/RelA and c-Rel and its DNA binding ability analyzed by EMSA. Taken together, our results suggest that delta(12)-PGJ(2)-induced apoptosis in HeLa cell utilized caspase cascade without Fas receptor-ligand interaction and accompanied with NF-kappaB inactivation.     

Structure and Catalytic Properties of Ceria-based Nickel Catalysts for CO<Subscript>2</Subscript> Reforming of Methane

Carbon dioxide reforming (CDR) of methane to synthesis gas over supported nickel catalysts has been reviewed. The present review mainly focuses on the advantage of ceria based nickel catalysts for the CDR of methane. Nickel catalysts supported on ceria–zirconia showed the highest activity for CDR than nickel supported on other oxides such as zirconia, ceria and alumina. The addition of zirconia to ceria enhances the catalytic activity as well as the catalyst stability. The catalytic performance also depends on the crystal structure of Ni–Ce–ZrO₂. For example, nickel catalysts co-precipitated with Ce_0.8Zr_0.2O₂ having cubic phase gave synthesis gas with CH₄ conversion more than 97% at 800 °C and the activity was maintained for 100 h during the reaction. On the contrary, Ni–Ce–ZrO₂ having tetragonal phase (Ce_0.8Zr_0.2O₂) or mixed oxide phase (Ce_0.5Zr_0.5O₂) deactivated during the reaction due to carbon formation. The enhanced catalytic performance of co-precipitated catalyst is attributed to a combination effect of nano-crystalline nature of cubic Ce_0.8Zr_0.2O₂ support and the finely dispersed nano size NiO _x crystallites, resulting in the intimate contact between Ni and Ce_0.8Zr_0.2O₂ particles. The Ni/Ce–ZrO₂/θ–Al₂O₃ also exhibited high catalytic activity during CDR with a synthesis gas conversion more than 97% at 800 °C without significant deactivation for more than 40 h. The high stability of the catalyst is mainly ascribed to the beneficial pre-coating of Ce–ZrO₂ resulting in the existence of stable NiO _x species, a strong interaction between Ni and the support, and an abundance of mobile oxygen species in itself. TPR results further confirmed that NiO _x formation was more favorable than NiO or NiAl₂O₄ formation and further results suggested the existence of strong metal-support interaction (SMSI) between Ni and the support. Some of the important factors to optimize the CDR of methane such as reaction temperature, space velocity, feed CO₂/CH₄ ratio and H₂O and/or O₂ addition were also examined.     

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Exploratory synthesis in the K–In–Ge–As system has yielded the unusual layered compounds K₈In₈Ge₅As₁₇(1) and K₅In₅Ge₅As₁₄(2), both of which contain In–Ge–As layers with interleaved potassium ions, Ge–Ge bonds, InAs₄tetrahedra, As–As bonds, and rows of Ge₂As₆dimers. Compound 1 has As₃groups, while compound 2 has infinite As ribbons on both faces of each layer. Unlike compound 1, compound 2 has substitutional defects where indium partially occupies each of the three independent germanium sites in the ratio of 1:5 for In:Ge. This partial occupancy makes 2 an electron-precise compound. The Ge(In)–Ge(In) bond of 2 is longer than the Ge–Ge bond of 1, and this bond lengthening effect was confirmed by performing DFT-MO calculations on the model compounds H₃Ge–GeH₃and H₃Ge–InH⁻₃. Possible implications of electron imprecise formulas determined by X-ray crystal structure determinations are discussed. Compound 1: space groupP2₁/cwitha=18.394 (8) Å,b=19.087 (7) Å,c=25.360 (3) Å,β=105.71 (2)°,V=8571 (4) ų, andD_calcd=4.45g/cm³forZ=4. Refinement on 4455 reflections yieldedR(R_w)=6.8%(7.8%). Compound 2: space groupC2/mwitha=40.00 (1) Å,b=3.925 (2) Å,c=10.299 (3),β=99.97 (2)°,V=1592 (1) ų, andD_calcd= 4.55g/cm³forZ=8. Refinement on 1206 reflections yieldedR(R_w)=5.6% (5.7%).