Periodic density functional calculations have been used to investigate the structure and stability of epitaxial vanadium oxide films grown on the TiO2(001) anatase surface. The formation energy of ...films of V2O5 stoichiometry, initially low, is found to rapidly increase with the film thickness, at variance to what is obtained for reduced pseudomorphic VO2 films. This is in tune with results of oxygen-assisted molecular beam epitaxy. The oxidation of thick, viz. >2 monolayers (ML), VO2 films yields a c(2 × 2) reconstructed surface, in agreement with low energy electron diffraction. These films are composed by partially reduced inner V atoms in a distorted-octahedral environment, and by isolated surface dioxovanadium centers exhibiting a distorted trigonal-bipyramidal coordination. Single scattering simulations of X-ray photoelectron diffraction patterns have also been performed, taking both 2- and 3-ML surface surface-oxidized films as models. Results are in fair agreement with experiments referring to films grown in oxidizing conditions, which suggests that coherent vanadia ultrathin films could be formed in vanadia−titania catalysts. The electronic structure of the films has been finally studied, finding that the terminal oxygens carried by the surface dioxovanadium species have a strong nucleophilic character, which makes them potential active centers for selective oxidation catalysis.
To compare perioperative and long-term outcomes related to laparoscopic and open abdominal surgical management of cervical cancer.
Propensity-matched comparison of prospectively collected data ...(Canadian Task Force classification II-1).
University teaching hospital.
Sixty-five propensity-matched patient pairs (130 patients) undergoing either laparoscopy or open abdominal surgical procedures to treat cervical cancer.
Radical hysterectomy plus lymphadenectomy was performed via the laparoscopic (LRH) or open abdominal approach (RAH).
Baseline characteristics of the study populations were similar. In the LRH group the procedure was converted to open surgery in 2 patients (2%). Compared with the RAH group, patients undergoing LRH experienced less blood loss (200 vs 500 mL; p < .001), a lower transfusion rate (6% vs 22%; p = .02), similar operative time (245 vs 259.5 minutes; p = .26), and shorter length of hospital stay (4 vs 8 days; p < .001). No between-group differences in intraoperative complications were recorded (p = 1.0); however, a trend toward a lower postoperative complication rate (Accordion system grade ≥ 3) was observed for LRH compared with RAH (4 patients 6%) vs 12 patients 18%; p = .06). Five-year disease-free survival (p = .6, log-rank test) and overall survival (p = .31, log-rank test) did not differ statistically between women undergoing LRH or RAH.
Laparoscopy ensures the same results as open surgery insofar as radicality and long-term survival. Use of the laparoscopic approach is associated with improved short-term results, minimizing the occurrence of severe postoperative complications.
Density functional molecular cluster calculations are combined with X-ray photoelectron spectroscopy (XPS), quadrupolar mass spectrometry (QMS), and diffuse reflectance infrared Fourier transform ...(DRIFT) spectroscopy to investigate the interaction of CO2 with α-Al2O3 and partially reduced α-Al2O3. The electronic structure of the stoichiometric and partially reduced substrate, adsorbate geometries, chemisorption enthalpies, and adsorbate vibrational parameters are computed and discussed. Theoretical results agree quite well with experimental data and previous theoretical investigations. As far as the adsorbate−substrate interaction is concerned, the results of our calculations indicate that CO2 forms bidentate-chelating carbonate species. The bonding scheme of this surface complex implies a significant substrate → adsorbate transfer of charge (from the occupied dangling bond of a surface Lewis base site into one component of the CO2 2πu LUMO) assisted by a definitely weaker adsorbate → substrate donation (from one component of the CO2 1πg HOMO into an empty dangling bond of a surface Lewis acid site). Our estimate of the chemisorption enthalpy (−15 kcal/mol) agrees quantitatively with calorimetric data reported for CO2 adsorbed on high surface area α-alumina (−16.0 kcal/mol). Mao, C.-F.; Vannice, M. A. Appl. Catal. A 1994, 111, 151. According to XPS and QMS outcomes, theoretical results predict that the interaction of CO2 with partially reduced α-Al2O3 gives rise to the reduction of the adsorbate to CO and to the concomitant substrate reoxidation.
Density functional molecular cluster calculations have been used to investigate the interaction of SO2 with defect-free TiO2(110) and Ti2O3(101̄2) surfaces. Adsorbate geometries and chemisorption ...enthalpies have been computed and discussed. Several local minima have been found for TiO2(110), but only one seems to be relevant for the catalytic conversion of SO2 to S. In agreement with experiment, the bonding of SO2 to Ti2O3(101̄2) is much stronger than that on TiO2(110). Moreover, our results are consistent with the surface oxidation and the formation of strong Ti−O and Ti−S bonds. On both substrates, the bonding is characterized by a two-way electron flow involving a donation from the SO2 HOMO into virtual orbitals of surface Lewis acid sites ( ), assisted by a back-donation from surface states into the SO2 LUMO. However, the localization of surface states and the strength of back-donation are very different on the two surfaces. On TiO2(110), back-donation is weaker, and it involves unsaturated bridging O atoms, while on Ti2O3(101̄2), it implies the -based valence band maximum and significantly weakens the S−O bond.
To present our experience with laparoscopic hysterectomy (LH) for uteri weighing 1 kilogram or more and to provide a systematic review of the available English literature.
Retrospective analysis and ...review of the literature (Canadian Task Force Classification II-2).
Department of Obstetrics and Gynecology, University of Insubria, Varese, Italy.
All women in whom LH was attempted at the Department of Obstetrics and Gynecology, University of Insubria for uteri weighing ≥1 kg were included in the present study. Demographic characteristics and perioperative details of patients were prospectively recorded in our institutional surgical database. We also performed a systematic review of the English literature to identify studies including at least 1 case of LH for uteri weighing ≥1 kg.
Hysterectomy for uteri ≥1 kg was performed through a total laparoscopic approach with vaginal morcellation of the uterus in the majority of patients and transvaginal closure of the vaginal vault in all cases.
LH was attempted in a total of 71 women. The median uterine weight was 1120 g (1000-2860 g). Three (4.2%) conversions to open surgery were needed. The median operative time and blood loss were 120 minutes (55-360 minutes) and 200 mL (10-1000 mL), respectively. No intraoperative and 2 (2.8%) postoperative complications occurred. Our review identified 6 studies reporting details of LH for uteri weighing ≥1 kg for a total of 62 patients; conversion to open surgery was necessary in 6 (9.7%) patients, and an additional 13 (21%) received a minilaparotomic incision to extract the uterus. The overall complication rate reported in the literature was 11.4%.
LH represents a possibility even in cases of uteri weighing ≥1 kg. In a dedicated setting with high endoscopic experience, conversion and complication rates appear acceptable.
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