VUV photon induced fluorescence study of SF5CF3

The interaction of SF$_5$CF$_3$ with vacuum-UV radiation has been investigated by photon induced fluorescence spectroscopy. Total fluorescence yield and dispersed fluorescence spectra of SF$_5$CF$_3$ were recorded in the 200-1000 nm fluorescence window. In all cases, the fluorescence spectra resemble those of CF$_3$X (X=H, F, Cl, and Br) molecules. At photon energies below 20 eV, the emission is attributed to the excited CF$_3$ and CF$_2$ fragments. The threshold for the CF$_3$ emission is 10.2 ± 0.2 eV, giving an upper-limit estimate for the SF$_5$-CF$_3$ bond dissociation energy of 3.9 ± 0.3 eV. The excitation functions of the CF3 and CF2 emissions were measured in the photon energy range 13.6 – 27.0 eV. The resonant structures observed in SF$_5$CF$_3$ are attributed to electronic transitions from valence to Rydberg orbitals, following similar assignments in CF$_3$X molecules. The photoabsorption spectrum of SF$_5$CF$_3$ shows features at the same energies, indicating a strong contribution from Rydberg excitations

Community Foundations: Learning from a Collective Experience: Process of Systematization

The report of a community foundation strengthening program involving eight Mexican community foundations: Tecate CF, Frontera Norte CF, Matamoros CF, Oaxaca CF, Puebla CF, Fundación Comunidad, Fundación del Empresariado Chihuahuense (FECHAC), and Fundación Internacional de la Comunidad (FIC). The report is also available in Spanish

Biatrial Remodeling in Patients with Cystic Fibrosis

BACKGROUND: Previous studies have focused on left and right ventricular remodeling in cystic fibrosis (CF), whereas atrial function has not been assessed in detail so far. We sought to investigate left and right atrial (LA and RA) function in patients with CF. METHODS: This retrospective investigation included 82 CF patients (64 survivors and 18 non-survivors) who were referred to CF department over the period of four years, as well as 32 control subjects matched by age and gender. All participants underwent an echocardiographic examination including a strain analysis, which was performed offline and blinded for groups. RESULTS: LA and RA volume indexes were significantly higher in CF patients than in controls and were particularly high in CF non-survivors. LA conduit and reservoir functions were significantly worse in CF survivors and non-survivors, compared with control subjects. RA phasic function was not different between controls, CF survivors and non-survivors. The parameters of lung function (forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1)) and the LA and RA volume indexes were predictors of mortality in CF patients. However, in a multivariate analysis, only FVC was an independent predictor of mortality in CF patients. CONCLUSIONS: Our results suggest that both atria are enlarged, but only LA function is impaired in CF patients. LA reservoir and conduit function is particularly deteriorated in CF patients. Though statistical significance was not reached due to our limited sample size, there was a trend of deterioration of LA and RA function from controls across CF survivors to CF non-survivors. LA and RA enlargement represented predictors of mortality in CF patients

Vacuum-UV negative photoion spectroscopy of CF3Cl, CF3Br and CF3I

Using synchrotron radiation negative ions have been detected by mass spectrometry following vacuum-UV photoexcitation of trifluorochloromethane (CF$_3$Cl), trifluorobromomethane (CF$_3$Br) and trifluoroiodomethane (CF$_3$I). The anions F$^-$, X$^-$, F$_2^-$, FX$^-$, CF$^-$, CF$_2^-$ and CF$_3^-$ were observed from all three molecules, where X = Cl, Br or I, and their ion yields recorded in the range 8-35 eV. With the exception of Br$^-$ and I$^-$, the anions observed show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation. Dissociative electron attachment, following photoionization of CF$_3$Br and CF$_3$I as the source of low-energy electrons, is shown to dominate the observed Br$^-$ and I$^-$ signals, respectively. Cross sections for ion-pair formation are put on to an absolute scale by calibrating the signal strengths with those of F$^-$ from both SF$_6$ and CF$_4$. These anion cross sections are normalized to vacuum-UV absorption cross sections, where available, and the resulting quantum yields are reported. Anion appearance energies are used to calculate upper limits to 298 K bond dissociation energies for $D^0$(CF$_3$-X) which are consistent with literature values. We report new data for $D^0$(CF$_2$I$^-$-F) ≤ 2.7 ± 0.2 eV and $\Delta_fH^0_{298}$ (CF$_2$I$^+$) ≤ (598 ± 22) kJ mol$^{-1}$. No ion-pair formation is observed below the ionization energy of the parent molecule for CF$_3$Cl and CF$_3$Br, and only weak signals (in both I$^-$ and F$^-$) are detected for CF$_3$I. These observations suggest neutral photodissociation is the dominant exit channel to Rydberg state photoexcitation at these lower energies

Comparative frequency of Coagulation Factor II and Coagulation Factor V Alleles among new-born and senior citizens

Resistance to activated protein C is one of the most common inherited disorders associated with hereditary thrombophilia. A missense mutation in the gene coding for coagulation factor V (CF V Leiden) and which renders this procoagulant factor resistant to inactivation by activated protein C results in an inherited risk for venous thrombosis. Recently, another mutation has been identified in the prothrombin gene (CF II G20210A) which was also associated with increased risk for venous thrombosis. In this study, we sought to establish the frequency of the two alleles in a random sample of Maltese newborn and compare these with the frequencies of the same alleles among senior citizens and patients with clinical thrombophilia. The control population of 554 newborn samples processed for the same point mutations gave 13 (2.3%) who were CF V Leiden heterozygotes and 7 (2.7%) who were CF II G20210A heterozygotes. Neither homozygotes nor trans-heterozygotes (i.e. CF V Leden and CF II2 0210A heterozygotes) were observed. The 348 senior citizens gave 9 (2.6%) CF V Leiden heterozygotes and 8 (2.4%) CF II G20210A heterozygotes. Neither homozygotes nor trans-heterozygotes (i.e. CF V Leden and CF II20210A heterozygotes) were observed. The 328 patients referred to the Laboratory of Molecular Genetics, University of Malta, with clinical thrombosis gave 23 (7.01%) CF V Leiden heterozygotes and 24 (7.31%) CF II G20210A heterozygous. One patient was found to be trans-heterozygous for the two mutations. The data suggested that although CF V G1691A and CF II G20210A may increase risk for thrombophilia, they do not impact on the survival of the carriers, but the transheterozygozity may also confer increased risk. The high allele frequency may be best explained by positive natural selection.peer-reviewe

Effects of corrective feedback on EFL speaking task complexity in China’s university classroom

Corrective feedback (CF) and task complexity are two important pedagogical topics in second language acquisition research in recent years, but there is few research investigating effects of CF on speaking task complexity in China’s university classroom settings. This research, through conducting different versions of speaking task experiments among 24 university students in China, explores the effect of teachers’ CF on English as a Foreign Language (EFL) speaking task complexity. According to the analysis of first-hand data, this research finds CF has different effects on EFL oral production with different task complexity. In simple speaking task, the effects of five kinds of CF (from largest to smallest) are listed as follows: clarification quest, metalinguistic feedback, recast, repetition and confirmation check. Regarding complex speaking task, the effects of five categorized CF are ranked from largest to smallest as follows: metalinguistic feedback, confirmation check, recast, clarification request and repetition. Improving to provide CF in pedagogical practice is an important contribution to promote EFL speaking task, so, on the basis of above research results, appropriate ways and forms of providing CF are expected to promote efficiency of CF in EFL classroom under the context of Chinese university classroom