Study of the δ− → π +π−π− Decay Mode

No enhancement in δ^? → π ⁺π^?π^? decay mode appeared at mass 962 MeV or at 996 MeV produced in π^?p → δ^?p interaction near its production threshold in a missing mass counter experiment. This finding fully supports the fact that the δ^? → π ⁺π^?π^? decay mode is not allowed by the conservations of the angular momentum and the parity.     

Characterization of the Metrology beamline at the SOLEIL synchrotron and application to the determination of mass attenuation coefficients of Ag and Sn in the range 3.5 ≤ E ≤ 28 keV

This work presents the new Metrology beamline at the SOLEIL synchrotron facility and a first attempt to quantitative measurements of mass attenuation coefficients for Ag and Sn performed on the hard X‐ray branch. We first describe the beamline itself and the characterization performed of the unfocused monochromatic beam running mode. We performed a first experimental measurement of mass attenuation coefficients in the range 3.5 ≤ E ≤ 28 keV and we also derived the K‐absorption and L‐absorption jump ratios. The results are compared with theoretical values as well as with other experimental data and agree well with previous published values. Copyright © 2011 John Wiley & Sons, Ltd.     

A new method for functionalizing α,γ‐dinitro compounds at the β‐position: application to the cyclization of β‐alkoxy‐α,γ‐dinitro compounds

Treatment of 2,4‐dinitropentane with bromine and sodium methoxide in methanol, affords formation of an ether product, 2,4‐dibromo‐3‐methoxy‐2,4‐dinitropentane, in 59% yield as a mixture of three diastereomers. This observation has led to a general synthesis of 3‐alkoxy‐2,4‐dibromo‐2,4‐dinitropentanes, obtained in 75‐86% yield from 2,4‐dibromo‐2,4‐dinitropentane as the preferred reactant. 4‐Bromo‐2,4‐dinitro‐2‐pentene has been identified as an intermediate in these reactions. The nitroalkene has been isolated and undergoes conjugate addition with alkoxides to afford the same ether products after brominative work‐up. The nitroalkene undergoes conjugate addition with sodium azide to give 3‐azido‐2,4‐dibromo‐2,4‐dinitropentane in 38% yield as a mixture of two isomers in which the (R*,R*) isomer predominates. Sequential treatment of 2,4‐dibromo‐2,4‐dinitropentane with sodium methoxide followed by sodium iodide and acetic acid gives 3‐methoxy‐2,4‐dinitropentane in 63% yield, the overall product of simple methoxylation of 2,4‐dinitropentane. However, attempted complete debromination of 2,4‐dibromo‐3‐methoxy‐2,4‐dinitropentane with excess sodium iodide and acetic acid results only in monodebromination to give 2‐bromo‐3‐methoxy‐2,4‐dinitropentane in 86% yield. Likewise, 2‐bromo‐3‐ethoxy‐2,4‐dinitropentane is formed in 93% yield from the ethoxy analog. A mechanistic rationale is offered for condition‐specific removal of the second Br atom in these reactions. Treatment of 3‐methoxy‐2,4‐dinitropentane with potassium acetate/iodine in dimethyl sulfoxide affords formation of 4,5‐dihydro‐3,4‐dimethyl‐3‐methoxy‐4‐nitroisoxazole 2‐oxide in 30% yield as a single diastereomer. Conversion of 2‐bromo‐3‐methoxy‐2,4‐dinitropentane in 15% yield to 4,5‐dihydro‐3,4‐dimethyl‐3‐methoxy‐4‐nitroisoxazole 2‐oxide is also possible by using potassium acetate in dimethyl sulfoxide. The mechanistic pathways for formation of 4,5‐dihydro‐3,4‐dimethyl‐3‐methoxy‐4‐nitroisoxazole 2‐oxide apparently involve unstable 3‐methoxy‐1,2‐dimethyl‐1,2‐dinitrocyclopropane as the common intermediate. Similarly, 2‐bromo‐3‐ethoxy‐2,4‐dinitropentane affords 4,5‐dihydro‐3‐ethoxy‐3,4‐dimethyl‐4‐nitroisoxazole 2‐oxide in 13% yield. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental study of the time-dependent rate of K → πππ

The time-dependence of the decay rate of initially pure K⁰ into the final state (π⁺π⁻π⁰) has been studied in search for the decay k_S⁰→π⁺π⁻π⁰. No evidence is found in a sample of 384 observed events. The ratio of the CP -violating K_S⁰ amplitude and the K_L⁰ amplitude is η₊₋₀ = (0.13_−0.20^+0.17) + i(0.17_−0.26^+0.27); the ratio of the CP-conserving K_S⁰ amplitude and the K_L⁰ amplitude is < 0.4. The energy dependence of the K⁰→π⁺π⁻π⁰ matrix element is found to be a₊₋₀ = −0.31 ± 0.03.     

The study of the structure and bioactivity of the B2O3 • Na2O • P2O5 system

In this study, we have investigated calcium and silicate‐free samples over a wide compositional range in the xB₂O₃·30 Na₂O·(70−x)P₂O₅ system, with 0 ≤ x ≤ 70 mol%, in order to determine the influence of the chemical composition on their structure and bioactive response in simulated body fluid. Information related to the chemical structures present in the network was obtained by means of Raman and infrared spectroscopy. For samples containing small amounts of P₂O₅, boron structures are preponderant. Upon increasing the phosphorus content, the samples' network is based on phosphate chains linked by boron groups through ‘P–O–B’ bridges. For high concentration of P₂O₅, the Q³ units form three‐dimensional network, whereas Q² units assist the chain formation. Regarding the in vitro assessment of bioactivity, the clear print of PO₄ asymmetric bending vibrations of apatite‐like layer in the 540–680 cm⁻¹ spectral domain, the scanning electron micrographs and energy dispersive x‐ray analysis spectra demonstrate that the studied borophosphate samples exhibit good bioactive response only for certain chemical compositions. More exactly, the highest bioactivity is obtained for 30% and 20% B₂O₃ (mol%) after 3 and 11 days of immersion, respectively. Therefore, the samples with 20–30 mol% boron content are valuable candidates that can be used as materials for tissue engineering applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Measurement of the (K → πμν)/(K → πeν) branching ratio

Partial branching ratios $\text{(}\text{K}{}^{\mathrm{+}}\text{→ π}{}^0\text{μ}{}^{\mathrm{+}}\text{ν)}\text{(}\text{K}{}^{\mathrm{+}}\text{→ π}{}^0\text{e}{}^{\mathrm{+}}\text{ν)}$ have been measured in six lepton momentum bins between 120 and 180 MeV/c. From these, six relations between the form factor slopes λ₊ and λ⁰ have been derived. Using the world average value λ₊ = 0.029 ± 0.003 and combining the six partial results on λ₀, we obtain λ₀ = 0.019 ± 0.010. This value is in agreement with the Callan-Treiman relation and other predictions. Together with recent K_$\text{l}$3⁰ results, it supports the $\text{ΔI =}\text{1}\text{2}$ rule. The agreement of our result with the value of λ₀ obtained from K_μ3 Dalitz-plot studies supports muon-electron universality.     

Upper limit on the decay Σ(1385)→Σγ and cross section for γΣ→Λπ

Coherent Λπ⁻ production on Pb of 600 GeV Σ⁻ hyperons has been studied with the SELEX facility at Fermilab. Using the Primakoff formalism, we set a 90% CL upper limit on the radiative decay width Γ[Σ(1385)⁻→Σ⁻γ]<9.5 keV, and estimate the cross section for γΣ⁻→Λπ⁻ at  GeV to be 56±16 μb.     

Note on the angular analysis of the decay J/ψ→f(→ππ)+γ

We derive the general (4-parameter) angular decay distribution for the cascade decay J/ψ→f(→ππ)+γ and determine its angular coefficients from the absorptive and dispersive contributions of the lowest order QCD diagram.     

Observation of χb production in the exclusive reaction ′→γγχb→γγ→γγ(eeorμμ−)

We report on the observation of 1 ³P_J (χ_b) production in the reaction ′→γχ_b→γγ→γγ(e⁺e⁻ or μ⁺μ⁻). The data were recorded with the nonmagnetic CUSB detector at the Cornell Electron Storage Ring, CESR. We observe 124 γγ events with either an electron or muon pair in the final state. In the γγ correlation plot about 40% of the events cluster around (120, 430) MeV.     

Symmetry breaking and the decays ψ′ → J/ψπ(η) and J/ψ → η(η′) γ

The theoretical mechanisms for the decays ψ′ → ψπ⁰ and ψ′ → ψη, which violate SU₂ and SU₃, respectively discussed. It is argued that symmetry breaking in the decay amplitudes may be as important as π⁰ −η −η′ mixing. The π⁰ −η mechanism ψ′ → ψν → ψπ⁰ leads to Γ(ψ′ → ψπ⁰) = (3.3±1.0) × 10⁻³ Γ(ψ′ → ψν), but this number may be enhanced by a factor as large as 12 by π⁰−η′ mixing and isospin violation in the decay amplitude. The related decays ψ → ηγ and ψ → η′γ are also discussed.     

A search for the decay μ → e γ

We report on the final analysis of a search for the decay μ⁺→e⁺γ performed at SIN. No evidence for the existence of the process has been found. An upper limit for the branching ratio of 1.0 × 10^?9 (90% confidence) is presented. The measured positron-photon energy distributions are completely described by the decay $\text{μ}{}^{\mathrm{+}}\text{→}\text{e}{}^{\mathrm{+}}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{ν}{}_{\mathrm{\mu }}\text{γ}$ and accidental coincidences.     

Nanomechanics of single keratin fibres: A Raman study of the α‐helix →β‐sheet transition and the effect of water

The use of micro‐Raman spectroscopy, through chemical‐bond, nano‐scale probes, allows the changes in conformations (α‐helix →β‐sheet), chain orientation, breakage of disulfide bonds (20%) and the increase of intra‐ and inter‐chain distances during the application of stress to be distinguished. The combination of micro‐Raman spectroscopy and a Universal Fibre Tester allows a quantitative measurement of the extension of chemical bonds in the peptide chain during loading. The nano‐structural transformations of keratin during strain of human hair in a dry environment (40–60% relative humidity) and saturated with water have been studied. Water permits the sliding of the chains and decreases the bond energy of the hair. Spectral analyses and 2D correlation are two coherent and independent methods to follow the structural nano‐mechanical (Raman) and micro‐mechanical (strain/stress) analyses, and confirm the validity of the experimental results, tools and principles used, as well as the agreement with the structural model of keratin fibres described by Chapman and Hearle. Copyright © 2006 John Wiley & Sons, Ltd.     

The ν3 − ν4 difference band contribution to the CCl4 symmetric stretch (ν1) mode

The Raman spectrum of the symmetric stretching vibration (ν₁) of liquid carbon tetrachloride observed at 295 K and reported repeatedly over the last 80 years clearly shows four of the five more abundant isotopomers at 440–470 cm⁻¹. At the lower energy end of this spectrum, additional intensity due to isotopomeric contributions from the symmetric stretch for v = 1 → 2 (hotbands) partially overlaps the prominent v = 0 → 1 features, and accounts for about 18% of the integrated intensity at 295 K in agreement with theory. When these two patterns are modeled and subtracted from the experimental spectrum, a feature underlying almost exactly the C³⁵Cl₄ (v = 0 → 1) band at 462.5 cm⁻¹ becomes apparent. We propose that this feature is the ν₃ − ν₄ difference band. Observations at lower temperatures, and of the combination bands, and the polarized Raman spectra are consistent with this hypothesis. Copyright © 2014 John Wiley & Sons, Ltd.     

A measurement of the η radiative width Γη→γγ

The radiative width of the η meson has been measured at PETRA in photon-photon collisions. The resulting value is Γ_η→γγ = 0.53±0.04±0.04 keV.     

Relative stabilities and molecular structures of the isomeric enol ethers and carboxylic esters derived from α‐acetyl‐γ‐butyrolactone and α‐acetyl‐δ‐valerolactone

Recently recorded ¹⁷O NMR spectra of compounds studied in a previous work (Taskinen E. Acta Chem. Scand. 1985; B39 : 489–494) dealing with the thermodynamics of isomerization of the enol ethers of α‐acetyl‐γ‐butyrolactone reveal an error in compound identification, caused by an unexpected isomerization reaction during the synthetic procedure. Thus, acid‐catalyzed treatment of the lactone with HC(OR)₃ in the respective alcohol ROH is shown to lead initially to the desired enol ethers which, however, are gradually isomerized to a mixture of the enol ethers and an ester of 2‐methyl‐4,5‐dihydrofuran‐3‐carboxylic acid. As a result, only one of the two isomeric compounds detected in the previous equilibration study was the expected enol ether (the thermodynamically more stable E isomer) of α‐acetyl‐γ‐butyrolactone, while the other, dominating species was the respective carboxylic ester. In the present work, the evidence provided by the ¹⁷O NMR spectra is presented, and the relative stabilities of the isomeric compounds are discussed on the basis of computational enthalpy data. The treatment is also extended to the respective isomeric compounds derived from α‐acetyl‐δ‐valerolactone. Copyright © 2007 John Wiley & Sons, Ltd.     

η,η′→ππγ with coupled channels

The decays η,η′→π⁺π⁻γ are investigated within an approach that combines one-loop chiral perturbation theory with a coupled channel Bethe–Salpeter equation which satisfies unitarity constraints and generates vector mesons dynamically from composite states of two pseudoscalar mesons. It is furthermore shown that the inclusion of the η′ as a dynamical degree of freedom does not renormalize the Wess–Zumino–Witten term.     

Raman spectroscopy of the transition of α‐gallium oxyhydroxide to β‐gallium oxide nanorods

The thermo‐Raman spectra of synthesised α‐gallium oxyhydroxide nanorod prove that the transition of α‐gallium oxyhydroxide to β‐gallium oxide nanorods occurs above 350 °C but below 400 °C. Scanning electron microscopy proves that the morphology of the α‐gallium oxyhydroxide nanorods is retained upon calcination to β‐gallium oxide. X‐ray diffraction patterns show that the nanorods are α‐gallium oxyhydroxide converting upon calcination to β‐gallium oxide. Intense Raman bands are observed at 190, 262, 275, 430, 520, 605, and 695 cm⁻¹, which undergo a red shift of ∼5 cm⁻¹ upon heating to 350 °C. Upon thermal treatment above 350 °C, the Raman spectrum shows a significantly different pattern. Raman bands are observed at 155, 212, 280, 430, 570, and 685 cm⁻¹. The thermo‐Raman spectra are in harmony with the TG and DTG patterns, which show that the reaction of α‐gallium oxyhydroxide to β‐gallium oxide occurs at 365 °C. Copyright © 2008 John Wiley & Sons, Ltd.     

Theoretical investigation on the excited‐state intramolecular proton transfer mechanism of 2‐(2′‐benzofuryl)‐3‐hydroxychromone

Spectroscopic studies on excited‐state proton transfer of a new chromophore 2‐(2′‐benzofuryl)‐3‐hydroxychromone (BFHC) have been reported recently. In the present work, based on the time‐dependent density functional theory (TD‐DFT), the excited‐state intramolecular proton transfer (ESIPT) of BFHC is investigated theoretically. The calculated primary bond lengths and angles involved in hydrogen bond demonstrate that the intramolecular hydrogen bond is strengthened. In addition, the phenomenon of hydrogen bond reinforce has also been testified based on infrared (IR) vibrational spectra as well as the calculated hydrogen bonding energies. Further, hydrogen bonding strengthening manifests the tendency of excited state proton transfer. Our calculated results reproduced absorbance and fluorescence emission spectra of experiment, which verifies that the TD‐DFT theory we used is reasonable and effective. The calculated Frontier Molecular Orbitals (MOs) further demonstrate that the excited state proton transfer is likely to occur. According to the calculated results of potential energy curves along O―H coordinate, the potential energy barrier of about 14.5 kcal/mol is discovered in the S₀ state. However, a lower potential energy barrier of 5.4 kcal/mol is found in the S₁ state, which demonstrates that the proton transfer process is more likely to happen in the S₁ state than the S₀ state. In other words, the proton transfer reaction can be facilitated based on the photo‐excitation effectively. Moreover, the phenomenon of fluorescence quenching could be explained based on the ESIPT mechanism. Copyright © 2015 John Wiley & Sons, Ltd.     

High‐resolution stimulated Raman spectroscopy and analysis of the ν1, 2ν1–ν1, ν2, 2ν2, and 3ν2–ν2 bands of CF4

The spectra of the ν₁, 2ν₁–ν₁, ν₂, 2ν₂, and 3ν₂–ν₂ bands of CF₄ were obtained with a quasi‐continuous wave stimulated Raman spectrometer. These five bands were studied at a temperature of 135 and 300 K (for the hot bands). The spectrum of ν₁ was obtained at a sample pressure of 2 mbar. For the spectra of the other regions, which are much weaker, higher pressures were used. The analysis has been performed thanks to the xtds and spview softwares developed in Dijon for such highly symmetric molecules. Combining the present results with a previous infrared study, we could determine a very accurate value for the C–F equilibrium bond length, i.e. r_e = 1.31588(6) Å. Copyright © 2013 John Wiley & Sons, Ltd.