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We have reported the energies and transition parameters for allowed transition (electric dipole, E1), and forbidden transitions (electric quadrupole, E2, and magnetic dipole, M1) for quadruply ionized radon (Rn V, Z = 86) for energetically low lying levels. The present results were performed using two independent computational strategies of the Hartree-Fock calculation with relativistic corrections and superposition of configurations (Cowan's HFR method) and the general-purpose relativistic atomic structure package based on the fully relativistic multiconfiguration Dirac-Fock (MCDF) method. We have compared our results with the results available in the literature to assess the accuracy of the data. We predict that new energy levels and transition parameters, where no other experimental or theoretical results are available, will form the basis for future experimental work. [ABSTRACT FROM AUTHOR]

The energies and lifetimes for 5p 6 , 5p 5nf (n = 4-10), 5p 5np (n = 6-10), 5p 5nh (n = 6-10), 5p 5nd (n = 5-10), 5p 5ns (n = 6-10), 5p 5ng (n = 5-10), and 5p 5ni (n = 7-10) configurations and the transition parameters for allowed transition (electric dipole E1), and forbidden transitions (electric quadrupole E2, and magnetic dipole M1) are presented for triply ionized lanthanum (La IV, Z = 57). The present results are obtained from a Hartree-Fock calculation with relativistic corrections and superposition of configurations (Cowan's HFR method) and generalpurpose relativistic atomic structure package based on a fully relativistic multiconfiguration Dirac-Fock method. Comparisons are made with experimental and other available theoretical results to assess the reliability and accuracy of the present calculations. Moreover, some new wavelengths, oscillator strengths and transition probabilities of E1, E2, and M1 transitions have been obtained using these methods. These results are reported for the first time in this work. [ABSTRACT FROM AUTHOR]

We have reported the energies and radiative lifetimes of levels for doubly ionized xenon (Xe III) and radon (Rn III). The calculations have been performed using the general-purpose relativistic atomic structure package based on fully relativistic multiconfiguration Dirac–Fock method. We have compared the results obtained from this work for (Xe III) with previous works in available literature. For (Rn III), there is no data except a few energy levels. Hence, we have presented new values on the energy levels of (Rn III). [ABSTRACT FROM AUTHOR]

Objectives: To investigate the role of anti-human heat shock protein 60 (hHsp60) antibody positivity in the pathogenesis of ectopic pregnancy, following Chlamydia trachomatis (CT) infection.Study Design: In a case-control study, serological tests for anti-hHsp60 were performed in ectopic pregnancies (study group) and parturients with normal reproductive histories (control group). All participants in both groups were CT IgG(+). hHsp60 IgG(+) prevalences were compared between the two groups, by semiquantitative ELISA. Data were evaluated using nonparametric and parametric tests and multivariable regression.Results: After an initial pilot study, two groups were formed: 63 ectopic gestations (study group) and 95 normal parturients (control group), all CT IgG(+). Blood samples from all cases were tested for anti-hHsp60 IgG. Age, gravidity, and practising contraception were higher in the control group, while a history of pelvic infections were more common in the study group. Hsp60 IgG(+) was found to be significantly higher in the control group (63/95, 66.3%) compared to study group (30/63, 47.6%). Regression analysis revealed anti-hHsp60 positivity was an independent factor delineating the two groups.Conclusion: Immunity to hHsp60 is less common in CT IgG(+) ectopic pregnancies than CT IgG(+) fertile subjects without a history of ectopic pregnancies. Hence, our findings suggest that hHsp60 seropositivity may decrease the probability of an ectopic gestation in subjects with previous CT infections. [ABSTRACT FROM AUTHOR]

Using the general-purpose relativistic atomic structure package based on the fully relativistic multiconfiguration Dirac–Fock method, we have reported the electric dipole transition (E1) parameters such as wavelengths, weighted oscillator strengths, transition rates (or probabilities) and line strengths for 5s-5p and 5p-5d transitions in Xe2+. In calculations, the Breit interaction and quantum electrodynamic effects have been included as perturbations. The calculated values for energy levels including valence and core-valence correlation have been compared with other available experimental and theoretical values in literature. Our transition results can provide useful data for, in particular, experimental works in future. [ABSTRACT FROM AUTHOR]

A chromium(I) dinitrogen complex reacts rapidly with O2 to form the mononuclear dioxo complex [TptBu,MeCrV(O)2] (TptBu,Me=hydrotris(3-tert-butyl-5-methylpyrazolyl)borate), whereas the analogous reaction with sulfur stops at the persulfido complex [TptBu,MeCrIII(S2)]. The transformation of the putative peroxo intermediate [TptBu,MeCrIII(O2)] (S=3/2) into [TptBu,MeCrV(O)2] (S=1/2) is spin-forbidden. The minimum-energy crossing point for the two potential energy surfaces has been identified. Although the dinuclear complex [(TptBu,MeCr)2(µ-O)2] exists, mechanistic experiments suggest that O2 activation occurs on a single metal center, by an oxidative addition on the quartet surface followed by crossover to the doublet surface. [ABSTRACT FROM AUTHOR]

A chromium(I) dinitrogen complex reacts rapidly with O2 to form the mononuclear dioxo complex [TptBu,MeCrV(O)2] (TptBu,Me=hydrotris(3-tert-butyl-5-methylpyrazolyl)borate), whereas the analogous reaction with sulfur stops at the persulfido complex [TptBu,MeCrIII(S2)]. The transformation of the putative peroxo intermediate [TptBu,MeCrIII(O2)] (S=3/2) into [TptBu,MeCrV(O)2] (S=1/2) is spin-forbidden. The minimum-energy crossing point for the two potential energy surfaces has been identified. Although the dinuclear complex [(TptBu,MeCr)2(μ-O)2] exists, mechanistic experiments suggest that O2 activation occurs on a single metal center, by an oxidative addition on the quartet surface followed by crossover to the doublet surface. [ABSTRACT FROM AUTHOR]

Dinitrogen complexes of the type TpR,RCr–N2–CrTpR,R are not the most labile precursors for Cr(i) chemistry, as they are sterically protected from obligatory associative ligand substitution. A mononuclear alkyne complex – TptBu,MeCr(η2-C2(SiMe3)2) – proved to be much more reactive. [ABSTRACT FROM AUTHOR]

Pancreatic ductal adenocarcinoma (PDAC) is almost universally fatal. The annual number of deaths equals the number of newly diagnosed cases, despite maximal treatment. The overall 5-year survival rate of <5% has remained stubbornly unchanged over the last 30 years, despite tremendous efforts in preclinical and clinical science. There is unquestionably an urgent need to further improve our understanding of pancreatic cancer biology, treatment response and relapse, and to identify novel therapeutic targets. Rigorous research in the field has uncovered genetic aberrations that occur during PDAC development and progression. In most cases, PDAC is initiated by oncogenic mutant KRAS, which has been shown to drive pancreatic neoplasia. However, all attempts to target KRAS directly have failed in the clinic and KRAS is widely assumed to be undruggable. This has led to intense efforts to identify druggable critical downstream targets and nodes orchestrated by mutationally activated KRAS. This includes context-specific KRAS effector pathways, synthetic lethal interaction partners and KRAS-driven metabolic changes. Here, we review recent advances in oncogenic KRAS signalling and discuss how these might benefit PDAC treatment in the future. [ABSTRACT FROM AUTHOR]

Metal coordination complexes of the sterically hindered β-diketonate, 2,6-dimesitylbenzoyl pinacolone (esac), are reported for Co, Ni, Cu, and Zn. All four form ML2-type complexes with typical coordination behavior for late-metal β-diketonates, however the effects on established electrochemistry and reactivity vary somewhat per metal. For example, the striking chemical and electrochemical inertness of CoII(esac)2 to oxidation and disproportionation is atypical. Conversely, the behavior of CuII(esac)2 is rather typical relative to other CuII(β-diketonate)2 complexes. These data suggest a relative disfavoring of certain reaction pathways, and represent an important step in modulating the catalysis of the base metals via sterically hindered β-diketonates. [ABSTRACT FROM AUTHOR]

A Kumada cross-coupling reaction catalyzed by iron acac was investigated using bulky acac ligands. Experimental data and DFT calculations support oxidative addition of an aryl-chloride to a high-spin FeII (acac)(alkyl) complex to give an FeIV intermediate Coordinating solvents THF and NMP appear to break apart catalytically-inactive halide-bridged metal dimers. [Display omitted] Iron β-diketonate compounds are reported using the hindered 2,6-dimesitylbenzoyl pinacolone (Aracac), which sterically precludes formation of tris-Aracac complexes. Fe(Aracac) 2 (1), Fe(Aracac) 2 Cl (2) were synthesized and characterized using crystallographic, spectroscopic, elemental analysis, and electrochemical techniques. Iron complexes with only one Aracac ligand form dimers [Fe(Aracac)(THF) 2 ] 2 (μ-OTf) 2 (3) and [(Aracac)Fe(μ-mesityl)] 2 (4). Complexes 1–4 were evaluated in a Kumada cross-coupling reaction and compared with the parent FeIII(acac) 3 complex. Whereas the bis-acac complexes 1 and 2 show only modest activity (∼50 % yield after 60 min), the mono-acac complexes 3 and 4 are nearly as effective as the parent compound (∼90 % yield). DFT computations, in conjunction with catalytic results and electrochemical observations, suggest a catalytic cycle involving an oxidative addition of an aryl-chloride to Fe(II) to produce a high-spin Fe(IV) complex that could alternately be described as a high-spin Fe(II) stabilizing two coordinated organoradicals. These results suggest that a unique aspect of acac as a ligand for this reaction is its ability to support high-spin organoiron complexes, which can provide low-barrier pathways for C–Cl bond cleavage and C C bond formation reactions. [ABSTRACT FROM AUTHOR]

Improvements in the syntheses of the carboxamide-substituted tris(pyrazolyl)borate ligands TpCONHPh,Me [tris(3-anilinocarbonyl-5-methylpyrazol-1-yl)borate] and TpCONH t-Bu,Me [tris(3- tert-butylaminocarbonyl-5-methylpyrazol-1-yl)borate] are reported. Their TlI salts, namely [tris(3-anilinocarbonyl-5-methylpyrazol-1-yl-κ N2)borato]thallium(I), [Tl(C33H31BN9O3)], (II), and [tris(3- tert-butylaminocarbonyl-5-methylpyrazol-1-yl-κ N2)borato]thallium(I), [Tl(C27H43BN9O3)], (III), as well as the CuI carbonyl complexes (TpCONHPh,Me)Cu(CO), namely carbonyl[tris(3-anilinocarbonyl-5-methylpyrazol-1-yl-κ N2)borato]copper(I) tetrahydrofuran trisolvate, [Cu(C33H31BN9O3)(CO)]·3C4H8O, (IV), and (TpCONH t-Bu,Me)Cu(CO), namely carbonyl[tris(3- tert-butylaminocarbonyl-5-methylpyrazol-1-yl-κ N2)borato]copper(I) tetrahydrofuran hemisolvate, [Cu(C27H43BN9O3)(CO)]·0.5C4H8O, (V), have been prepared. Their spectroscopic properties and structures are compared with those of related compounds. The molecules of (II)-(V) show hydrogen bonding to either solvent molecules or neighboring complex molecules via amide groups. The title compounds feature the ability to engage other ligands in hydrogen bonding and they show strong electron-withdrawing character. Compound (V) displays voids of ca 800 Å3 in the crystal structure. [ABSTRACT FROM AUTHOR]

This study analyzes the influence of chemical and physical properties of Pd/C and Pt/C hydrodechlorination (HDC) catalysts in the different evolution of their activity during time on stream. Pt/C showed stable activity in the HDC of dichloromethane (DCM) and chloroform (TCM), while Pd/C was deactivated after 90 h of operation, particularly during HDC of DCM. The deactivation of Pd/C catalyst can be attributed to the lower proportion of zero-valent species and larger metal particle size. This appears to hinder the H 2 dissociation, enhance the irreversible chemisorption of reactants and reaction products, and favor coupling reactions (leading to the formation of carbonaceous deposits) and/or metal phase change reactions. The more extensive deactivation of Pd/C in the HDC of DCM is attributed to the stronger chemisorption of the reactant on the catalyst, which leads to the formation of a new PdC x phase by the incorporation of carbon atoms into the metal lattice. [ABSTRACT FROM AUTHOR]

In collaboration with 62 population-based cancer registries contributing to the Automated Childhood Cancer Information System (ACCIS), we built a database to study incidence and survival of children and adolescents with cancer in Europe. We describe the methods and evaluate the quality and internal comparability of the database, by geographical region, period of registration, type of registry and other characteristics. Data on 88,465 childhood and 15,369 adolescent tumours registered during 1978-1997 were available. Geographical differences in incidence are caused partly by differences in definition of eligible cases. The observed increase in incidence rates cannot be explained by biases due to the selection of datasets for analyses, and only partially by the registration of non-malignant or multiple primary tumours. Part of the observed differences in survival between the regions may be due to variable completeness of follow-up, but most is probably explained by resource availability and organisation of care. Further standardisation of data and collection of additional variables are required so that this study may continue to yield valuable results with reliable interpretation. [ABSTRACT FROM AUTHOR]

Abstract: In collaboration with 62 population-based cancer registries contributing to the Automated Childhood Cancer Information System (ACCIS), we built a database to study incidence and survival of children and adolescents with cancer in Europe. We describe the methods and evaluate the quality and internal comparability of the database, by geographical region, period of registration, type of registry and other characteristics. Data on 88,465 childhood and 15,369 adolescent tumours registered during 1978–1997 were available. Geographical differences in incidence are caused partly by differences in definition of eligible cases. The observed increase in incidence rates cannot be explained by biases due to the selection of datasets for analyses, and only partially by the registration of non-malignant or multiple primary tumours. Part of the observed differences in survival between the regions may be due to variable completeness of follow-up, but most is probably explained by resource availability and organisation of care. Further standardisation of data and collection of additional variables are required so that this study may continue to yield valuable results with reliable interpretation. [Copyright &y& Elsevier]