Na-feldspar: temperature, pressure and the state of order

In feldspars, mean tetrahedral T–O bond lengths (T = Al,Si) are the standard measure of the tetrahedral Al content. However, for a sophisticated assessment of the Al,Si distribution, factors have to be accounted for (1) that cause individual T–O bond lengths to deviate from their tetrahedral means and (2) that cause mean tetrahedral lengths to deviate from values specified by the Al content. We investigated low albite, Na[AlSi3O8], from six X-ray crystal structure refinements available in the literature. The Al,Si distribution of low albite is fully ordered so that Al,Si–O bond length variations result only from bond perturbing factors. For the intra-tetrahedral variation ΔT–O≡T–O−⟨T–O⟩, only two factors turned out to be effective: (1) the sum of bond critical point electron densities in the Na–O and T–O bonds neighbouring the T–O bond under consideration and (2) the fractional s-bond character of the bridging oxygen atom. This model resulted in a root mean square (rms) value for ΔT–O of only 0.002 Å, comparable to the estimated standard deviations (esd\u27s) routinely quoted in X-ray and neutron structure refinements. In the second step, the inter-tetrahedral differences Δ⟨T–O⟩≡⟨T–O⟩−⟨⟨T–O⟩⟩ were considered. Here, apart from the tetrahedral Al content, the only size-perturbing factor is the difference between the tetrahedral and the grand mean fractional s-characters. The resulting rms value was as small as 0.0003 Å. From this analysis, Al site occupancies, t, can be derived from observed mean tetrahedral distances, 〈T–O〉$_{obs}$, as t =0.25(1+n$_{An}$)+(⟨T–O⟩$_{adj}$−⟨⟨T–O⟩⟩)/0.12466(17), with the observed distance 〈T–O〉$_{obs}$ adjusted for the influence of the fractional s-character, ⟨T–O⟩$_{adj}$=⟨T–O⟩$_{obs}$+0.1907(51)[⟨f$_{s}$(O)⟩−⟨⟨fs(O)⟩⟩]. This equation served to determine the site occupancies of 16 intermediate to high albites and one analbite from their mean tetrahedral distances. It was found that the individual site occupancies t$_{1}$0, t$_{1}$m and t$_{2}$0= t$_{2}$m all vary linearly with the difference Δt$_{1}$= t$_{1}$0− t$_{1}$m. Δt$_{1}$, in turn, varies linearly with the length difference, Δtr[110], between the unit cell repeat distances [1∕2a, 1∕2b, 0] and [1∕2a, −1/2b, 0]. Then, from the Δtr[110] indicator, values of t were obtained as t$_{1}$0=(1−b$_{0}$)+b$_{0}$(b$_{1}$+b$_{2}$Δtr[110]) t$_{1}$m =(1−b$_{0}$)−(1−b$_{0}$)(b$_{1}$+b$_{2}$Δtr[110]) t$_{2}$0 = t$_{2}$m=(b$_{0}$−0.5)−(b$_{0}$−0.5)(b$_{1}$+b$_{2}$Δtr[110]), with b$_{0}$=0.7288(16), b$_{1}$=0.1103(59) and b$_{2}$=3.234(32) Å$^{-1}$. Finally, from an expression that converts the Δ2θ(131) measure of order into Δtr[110] and thus into site occupancies, it was possible to obtain from the unique suite of bracketed high-pressure experiments performed on albites by Goldsmith and Jenkins (1985) the evolution with equilibrium temperature of the thermodynamic order parameter Qod and of the individual Al site occupancies t at a pressure of 1 bar. For that purpose, since the Goldsmith and Jenkins experiments were performed at ≈18 kbar, a procedure was devised that accounts for the effect of pressure on the state of order. At 1 bar, low albite is stable up to 590 ∘C, where it begins to disorder, turning into high albite above 720 ∘C. The highly though not fully disordered monoclinic state (monalbite) is reached at 980 ∘C, 1 bar, and 1055 ∘C, 18 kbar, respectively. Eventually, when applying the determinative equations given above to low microcline, full order is predicted as in low albite

Average chemical properties and potential formation pathways of highly oxidized organic aerosol

Measurements of ambient organic aerosol indicate that a substantial fraction is highly oxidized and low in volatility, but this fraction is generally not reproduced well in either laboratory studies or models. Here we describe a new approach for constraining the viable precursors and formation pathways of highly oxidized organic aerosol, by starting with the oxidized product and considering the possible reverse reactions, using a set of simple chemical rules. The focus of this work is low-volatility oxidized organic aerosol (LV-OOA), determined from factor analysis of aerosol mass spectrometer data. The elemental composition and volatility of the aerosol enable the determination of its position in a three-dimensional chemical space (defined by H/C, O/C, and carbon number) and thus its average chemical formula. Consideration of possible back-reactions then defines the movement taken through this chemical space, constraining potential reaction pathways and precursors. This approach is taken for two highly oxidized aerosol types, an average of LV-OOA factors from ten field campaigns (average formula C[subscript 10.5]H[subscript 13.4]O[subscript 7.3]), and extremely oxidized LV-OOA (from Mexico City, average formula C[subscript 10]H[subscript 12.1]O[subscript 8.4]). Results suggest that potential formation pathways include functionalization reactions that add multiple functional groups per oxidation step, oligomerization of highly oxidized precursors, and, in some cases, fragmentation reactions that involve the loss of small, reduced fragments.National Science Foundation (U.S.) (Grant CHE-1012809)National Science Foundation (U.S.) (Grant AGS-1056225

Towards the synthesis of selective CDK7 inhibitors as potential anti-cancer drugs

Cyclin-dependent kinase 7 (CDK7) exhibits an interesting target for an anti-cancer therapy approach. CDK7’s triple role in phosphorylation (cell cycle, transcription, estrogen receptor (ER)) in cell regulation makes this kinase interesting. Phosphorylation of cell cycle CDK’s via its CAK-complex, of Ser-5 in RNA-PolII as part of the TFIIH-complex and phosphorylation of Ser-118 in ER all show the importance of this enzyme. Given that CDKs are over-expressed in many cancers, selective inhibition of CDK7 should result in cell cycle arrest and apoptosis predominately in tumour cells. Previously, BS-181 (Figure 0.1) has been reported as the first CDK7 selective inhibitor, which displayed a good in vitro and in vivo profile.1 Based on this initial lead compound, a library of rational-designed analogues was synthesised. Much of this library was based on a computer-aided-drug-design (CADD) approach by docking, which gave valuable insights in possible binding modes and helped to focus targeting the whole active site. [Molecular structure diagrams appear here. To view, please open pdf attachment] Figure 0.1: BS-181 and new analogues. Several of these novel inhibitors showed excellent selectivity versus CDK2 in particular, and potency against CDK7 in the 30 – 60 nM range for their IC50-values. Cellular assays confirmed the growth inhibitory properties of these new compounds, with GI50-values in the low μM range. This work also demonstrates what functional groups were tolerated in the 3-,5- and 7-position. 1 Ali, S.; Heathcote, D. A.; Kroll, S. H. B.; Jogalekar, A. S.; Scheiper, B.; Patel, H.; Brackow, J.; Siwicka, A.; Fuchter, M. J.; Periyasamy, M.; Tolhurst, T. S.; Kanneganti, S. K.; Snyder, J. P.; Liotta, D. C.; Aboagye, E. O.; Barrett, A. G. M.; Coombes, R. C. Cancer Research 2009, 69, 6208.Imperial Users onl

Radiative Decays of Hyperons in the Skyrme Model: E2/M1 Transitions

We study the radiative decays of $J^\pi=\frac{3}{2}^+$ baryons in the framework of the SU(3) collective approach to the Skyrme model. We present the predictions for the decay widths and the corresponding $E2/M1$ ratios. We find that all considered ratios are negative and of the order of a few percent only. We discuss the effects of flavor symmetry breaking and compare our results to those obtained in related models.Comment: 10 pages LaTeX, no figure

Automated detection of residual cells after sex-mismatched stem-cell transplantation – evidence for presence of disease-marker negative residual cells

<p>Abstract</p> <p>Background</p> <p>A new chimerism analysis based on automated interphase fluorescence in situ hybridization (FISH) evaluation was established to detect residual cells after allogene sex-mismatched bone marrow or blood stem-cell transplantation.</p> <p>Cells of 58 patients were characterized as disease-associated due to presence of a bcr/abl-gene-fusion or a trisomy 8 and/or a simultaneous hybridization of gonosome-specific centromeric probes. The automatic slide scanning platform Metafer with its module MetaCyte was used to analyse 3,000 cells per sample.</p> <p>Results</p> <p>Overall 454 assays of 58 patients were analyzed. 13 of 58 patients showed residual recipient cells at one stage of more than 4% and 12 of 58 showed residual recipient cells less than 4%, respectively. As to be expected, patients of the latter group were associated with a higher survival rate (48 vs. 34 month). In only two of seven patients with disease-marker positive residual cells between 0.1–1.3% a relapse was observed. Besides, disease-marker negative residual cells were found in two patients without relapse at a rate of 2.8% and 3.3%, respectively.</p> <p>Conclusion</p> <p>The definite origin and meaning of disease-marker negative residual cells is still unclear. Overall, with the presented automatic chimerism analysis of interphase FISH slides, a sensitive method for detection of disease-marker positive residual cells is on hand.</p

Elemental ratio measurements of organic compounds using aerosol mass spectrometry: characterization, improved calibration, and implications

Elemental compositions of organic aerosol (OA) particles provide useful constraints on OA sources, chemical evolution, and effects. The Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is widely used to measure OA elemental composition. This study evaluates AMS measurements of atomic oxygen-to-carbon (O : C), hydrogen-to-carbon (H : C), and organic mass-to-organic carbon (OM : OC) ratios, and of carbon oxidation state ([bar over OS][subscript C]) for a vastly expanded laboratory data set of multifunctional oxidized OA standards. For the expanded standard data set, the method introduced by Aiken et al. (2008), which uses experimentally measured ion intensities at all ions to determine elemental ratios (referred to here as "Aiken-Explicit"), reproduces known O : C and H : C ratio values within 20% (average absolute value of relative errors) and 12%, respectively. The more commonly used method, which uses empirically estimated H[subscript 2]O[superscript +] and CO[superscript +] ion intensities to avoid gas phase air interferences at these ions (referred to here as "Aiken-Ambient"), reproduces O : C and H : C of multifunctional oxidized species within 28 and 14% of known values. The values from the latter method are systematically biased low, however, with larger biases observed for alcohols and simple diacids. A detailed examination of the H[subscript 2]O[superscript +], CO[superscript +], and CO[subscript 2][superscript +] fragments in the high-resolution mass spectra of the standard compounds indicates that the Aiken-Ambient method underestimates the CO[superscript +] and especially H[subscript 2]O[superscript +] produced from many oxidized species. Combined AMS–vacuum ultraviolet (VUV) ionization measurements indicate that these ions are produced by dehydration and decarboxylation on the AMS vaporizer (usually operated at 600 °C). Thermal decomposition is observed to be efficient at vaporizer temperatures down to 200 °C. These results are used together to develop an "Improved-Ambient" elemental analysis method for AMS spectra measured in air. The Improved-Ambient method uses specific ion fragments as markers to correct for molecular functionality-dependent systematic biases and reproduces known O : C (H : C) ratios of individual oxidized standards within 28% (13%) of the known molecular values. The error in Improved-Ambient O : C (H : C) values is smaller for theoretical standard mixtures of the oxidized organic standards, which are more representative of the complex mix of species present in ambient OA. For ambient OA, the Improved-Ambient method produces O : C (H : C) values that are 27% (11%) larger than previously published Aiken-Ambient values; a corresponding increase of 9% is observed for OM : OC values. These results imply that ambient OA has a higher relative oxygen content than previously estimated. The [bar over OS][subscript C] values calculated for ambient OA by the two methods agree well, however (average relative difference of 0.06 [bar over OS][subscript C] units). This indicates that [bar over OS][subscript C] is a more robust metric of oxidation than O : C, likely since [bar over OS][subscript C] is not affected by hydration or dehydration, either in the atmosphere or during analysis.National Science Foundation (U.S.) (CHE-1012809)National Science Foundation (U.S.) (ATM-1238109

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30