179 research outputs found
H(3)tren (3+) and H(4)tren (4+) fluoride zirconates or tantalates
Four new [H(3)tren](3+) or [H(4)tren](4+) fluoride zirconates and two new [H(3)tren](3+) fluoride tantalates are evidenced in the (ZrF4 or Ta2O5)-tren-HFaq.-ethanol systems at 190 degrees C: the structurally related phases [H(4)tren]center dot(Zr2F12)center dot H2O and alpha-[H(4)tren](center dot)(Zr2F12) (P2(1)2(1)2(1)). beta-[H(4)tren]center dot(Zr2F12) (P2(1/c)), [H(3)tren](4)center dot(ZrF8)(3)center dot 4H(2)O (123). beta-[H(3)tren](2)center dot(Ta3O2F16)center dot(F) (R32) and its monoclinic distortion alpha-[H(3)rren](2)center dot(Ta3O2F16)center dot(F) (C2/m). alpha and beta-[H(4)tren]center dot(Zr2F12) and [H(4)tren]center dot(Zr2F12)center dot H2O are built up from (Zr2F12) dimers of edge sharing ZrF7 polyhedra while isolated ZrF8 dodecahedra are found in [H(3)tren](4)center dot(ZrF8)(3)center dot 4H(2)O. Linear (Ta3O2F16) trimers build et and beta-[H(3)tren](2)center dot(Ta3O2F16)center dot(F); they consist of two (TaOF6) pentagonal bipyramids that are linked to two opposite oxygen atoms of one central (TaO2F4) octahedron. A disorder affects the equatorial fluorine atoms of the trimers and eventually carbon or nitrogen atoms of [H(3)tren](3+) cations. (C) 2011 Elsevier B.V. All rights reserved
2,4,6-Triamino-1,3,5-triazine-1,3-diium aquaÂpentaÂfluoridoaluminate
The title compound, (C3H8N6)[AlF5(H2O)], was obtained by solvothermal synthesis from the reaction of aluminium hydroxide, 1,3,5-triazine-2,4,6-triamine (melamine), aqueous HF and water at 323â
K for 48â
h. The structure consists of [AlF5(H2O)]2â octaÂhedra and diprotonated melaminium cations. Cohesion is ensured by a three-dimensional network of hydrogen bonds
X-band dual-polarization radar-based hydrometeor classification for Brazilian tropical precipitation systems
The dominant hydrometeor types associated with Brazilian tropical
precipitation systems are identified via research X-band dual-polarization
radar deployed in the vicinity of the Manaus region (Amazonas) during both
the GoAmazon2014/5 and ACRIDICON-CHUVA field experiments. The present study
is based on an agglomerative hierarchical clustering (AHC) approach that
makes use of dual polarimetric radar observables (reflectivity at horizontal
polarization ZH, differential reflectivity ZDR, specific
differential-phase KDP, and correlation coefficient ÏHV) and
temperature data inferred from sounding balloons. The sensitivity of the
agglomerative clustering scheme for measuring the intercluster
dissimilarities (linkage criterion) is evaluated through the wet-season
dataset. Both the weighted and Ward linkages exhibit better abilities to
retrieve cloud microphysical species, whereas clustering outputs associated
with the centroid linkage are poorly defined. The AHC method is then applied
to investigate the microphysical structure of both the wet and dry seasons.
The stratiform regions are composed of five hydrometeor classes: drizzle,
rain, wet snow, aggregates, and ice crystals, whereas convective echoes are
generally associated with light rain, moderate rain, heavy rain, graupel,
aggregates, and ice crystals. The main discrepancy between the wet and dry
seasons is the presence of both low- and high-density graupel within
convective regions, whereas the rainy period exhibits only one type of
graupel. Finally, aggregate and ice crystal hydrometeors in the tropics are
found to exhibit higher polarimetric values compared to those at
midlatitudes.</p
Impact of comorbidity indexes on non-relapse mortality.
Comorbidity indexes (CI) have been reported to predict non-relapse mortality (NRM) and overall survival after allogeneic hematopoietic stem cell transplantation (HSCT) (Charlson's comorbidity index (CCI), hematopoietic cell transplantation CI (HCT-CI) and the pre-transplantation assessment of mortality (PAM) score). Which of these indexes best predict survival is unknown yet. We retrospectively studied 286 patients who underwent allogeneic HSCT. HCT-CI and PAM scores required grading according to pre-transplant pulmonary function tests (PFTs), which were lacking for some patients. We thus designed a reduced HCT-CI and an adjusted PAM, without results of PFTs. Using CCI, 25% of patients had indexes of 1 or more; median reduced HCT-CI score was 1; median adjusted PAM score was 24. The discriminative properties of the three CIs were rather low in our population. Comparison of patients and transplant characteristics between our and Seattle group's cohorts, however, revealed significant differences in more children, in more cord blood HSCT and in HSCT for Fanconi anemia in St Louis. Finally, multivariate analysis of scoring items revealed that age, matched unrelated or mismatched donor and hepatic disease were associated with NRM in our cohort. Translating use for patient's counseling or decision to proceed to transplant of these CIs will need prospective studies in a large independent cohort
Silicon CMOS photonics platform for enabling high-speed DQPSK transceivers
In this work we review the results obtained under the framework of FP7-HELIOS project for integrated DQPSK transceivers in silicon photonics. A differential DQPSK receiver with balanced zero biased Germanium photodiodes has been demonstrated at 10Gbit/s with an error floor around 10(-15). Furthermore, DPSK modulation up to 10Gbit/s with a bit error rate below 10(-9) is also demonstrated using a silicon push-pull operated dual-drive Mach-Zehnder modulator (MZM) based on carrier depletion. The results indicate the potential of the silicon CMOS photonics platform for boosting next-generation optical networks based on advanced modulation formats
Global existence for a system of non-linear and non-local transport equations describing the dynamics of dislocation densities
In this paper, we study the global in time existence problem for the
Groma-Balogh model describing the dynamics of dislocation densities. This model
is a two-dimensional model where the dislocation densities satisfy a system of
transport equations such that the velocity vector field is the shear stress in
the material, solving the equations of elasticity. This shear stress can be
expressed as some Riesz transform of the dislocation densities. The main tool
in the proof of this result is the existence of an entropy for this syste
Advances in the Direct Study of Carbon Burning in Massive Stars
The C12+C12 fusion reaction plays a critical role in the evolution of massive stars and also strongly impacts various explosive astrophysical scenarios. The presence of resonances in this reaction at energies around and below the Coulomb barrier makes it impossible to carry out a simple extrapolation down to the Gamow window-the energy regime relevant to carbon burning in massive stars. The C12+C12 system forms a unique laboratory for challenging the contemporary picture of deep sub-barrier fusion (possible sub-barrier hindrance) and its interplay with nuclear structure (sub-barrier resonances). Here, we show that direct measurements of the C12+C12 fusion cross section may be made into the Gamow window using an advanced particle-gamma coincidence technique. The sensitivity of this technique effectively removes ambiguities in existing measurements made with gamma ray or charged-particle detection alone. The present cross-section data span over 8 orders of magnitude and support the fusion-hindrance model at deep sub-barrier energies
Postoperative complications after pancreatoduodenectomy for malignancy: results from the Recurrence After Whippleâs (RAW) study
Background
Pancreatoduodenectomy (PD) is associated with significant postoperative morbidity. Surgeons should have a sound understanding of the potential complications for consenting and benchmarking purposes. Furthermore, preoperative identification of high-risk patients can guide patient selection and potentially allow for targeted prehabilitation and/or individualized treatment regimens. Using a large multicentre cohort, this study aimed to calculate the incidence of all PD complications and identify risk factors.
Method
Data were extracted from the Recurrence After Whippleâs (RAW) study, a retrospective cohort study of PD outcomes (29 centres from 8 countries, 2012â2015). The incidence and severity of all complications was recorded and potential risk factors for morbidity, major morbidity (ClavienâDindo grade > IIIa), postoperative pancreatic fistula (POPF), post-pancreatectomy haemorrhage (PPH) and 90-day mortality were investigated.
Results
Among the 1348 included patients, overall morbidity, major morbidity, POPF, PPH and perioperative death affected 53 per cent (n = 720), 17 per cent (n = 228), 8 per cent (n = 108), 6 per cent (n = 84) and 4 per cent (n = 53), respectively. Following multivariable tests, a high BMI (P = 0.007), an ASA grade > II (P II patients were at increased risk of major morbidity (P < 0.0001), and a raised BMI correlated with a greater risk of POPF (P = 0.001).
Conclusion
In this multicentre study of PD outcomes, an ASA grade > II was a risk factor for major morbidity and a high BMI was a risk factor for POPF. Patients who are preoperatively identified to be high risk may benefit from targeted prehabilitation or individualized treatment regimens
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