5 research outputs found
Inhibition effects in the partial oxidation of cyclohexane on polymer supported Co(II) catalysts
No full textPolymer supported catalysts with different contents of metal ions where synthesized by wet impregnation of the degassed support from ethanolic solutions of cobalt(II) nitrate. Amacroreticular copolymer of poly-4-vinylpyridine with divinylbenzene was used as the support. The prepared catalysts were tested in the partial oxidation of cyclohexane to cyclohexanol and cyclohexanone. Activity tests were performed in a stainless steel, laboratory scale, stirred autoclave, in the semi batch regime under isothermal and non-isothermal conditions. Isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal conditions. isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal experiments, a constant heating rate of 0.3 degree/min was used in the range between 110 °C and 170 °C. Non-linear, least-squares analysis with the simplex optimization method and numerical simulation of the reaction model in each iterative step was used for the kinetic characterization of the process in a non-stationary, semi-batch regime. Apparent rate constants were obtained as an invariant measure of the catalytic system. Anon-linear effect of the content of metal ions on the reaction rate and on the ratio of the yield of the products was observed, which is attributed to a complex interactions between the reaction medium and the heterogeneous catalyst, including a catalyst-inhibition effect
Inhibition effects in the partial oxidation of cyclohexane on polymer supported Co(II) catalysts
No full textPolymer supported catalysts with different contents of metal ions where synthesized by wet impregnation of the degassed support from ethanolic solutions of cobalt(II) nitrate. Amacroreticular copolymer of poly-4-vinylpyridine with divinylbenzene was used as the support. The prepared catalysts were tested in the partial oxidation of cyclohexane to cyclohexanol and cyclohexanone. Activity tests were performed in a stainless steel, laboratory scale, stirred autoclave, in the semi batch regime under isothermal and non-isothermal conditions. Isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal conditions. isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal experiments, a constant heating rate of 0.3 degree/min was used in the range between 110 °C and 170 °C. Non-linear, least-squares analysis with the simplex optimization method and numerical simulation of the reaction model in each iterative step was used for the kinetic characterization of the process in a non-stationary, semi-batch regime. Apparent rate constants were obtained as an invariant measure of the catalytic system. Anon-linear effect of the content of metal ions on the reaction rate and on the ratio of the yield of the products was observed, which is attributed to a complex interactions between the reaction medium and the heterogeneous catalyst, including a catalyst-inhibition effect.Katalizatori na polimernom nosaču, sa različitim sadržajem metalnih jona, sintetisani su impregnacijom degaziranog nosača iz alkoholnog rastvora kobalt(II) nitrata. Makroretikularni kopolimer poli-4-vinilpriridina sa divinilbenzenom je korišćen kao nosač. Pripremljeni katalizatori su testirani u reakciji parcijalne oksidacije cikloheksana do smeše cikloheksanola i cikloheksanona. Katalitički testovi su izvedeni u laboratorijskom, autoklavu od nerđajućeg čelika, pod izotermalnim i neizotermalnim uslovima. Izotermalni eksperimenti su izvođeni na 170 °C tokom 120 min. U neizotermalnim eksperimentima korišćena je konstantna brzina grejanja od 0,3 °C/min, u intervalu 110 - 170 °C. Nelinearna analiza najmanjih kvadrata sa simpleks metodom optimizacije u numeričkom simulacijom u svakom iteracionom koraku, je korišćena za kinetičku karakterizaciju procesa u nestacionarnom režimu. Dobijene su prividne konstante brzine kao invarijantna karakteristika katalitičkog sistema. Uočeni su nelinearni efekti sadržaja metalnih jona na brzine reakcija i na odnose koncentracija proizvoda. Ovi efekti su pripisani složenoj interakciji reakcione sredine i heterogenog katalizatora, koja uključuje i inhibiciju
Early Bleeding After Laparoscopic Roux-en-Y Gastric Bypass: Incidence, Risk Factors, and Management — a 21-Year Experience
No full textPURPOSE: Morbidity and mortality associated with bariatric surgery are considered low. The aim of this study is to assess the incidence, clinical presentation, risk factors, and management of early postoperative bleeding (POB) after laparoscopic Roux-en-Y gastric by-pass (RYGB). MATERIALS AND METHODS: Retrospective analysis of prospectively collected data of consecutive patients who underwent RYGB in 2 expert bariatric centers between January 1999 and April 2020, with a common bariatric surgeon. RESULTS: A total of 2639 patients underwent RYGB and were included in the study. POB occurred in 72 patients (2.7%). Intraluminal bleeding (ILB) was present in 52 (72%) patients and extra-luminal bleeding (ELB) in 20 (28%) patients. POB took place within the first 3 postoperative days in 79% of patients. The most frequent symptom was tachycardia (63%). Abdominal pain was more regularly seen with ILB, compared to ELB (50% vs. 20%, respectively, p = 0.02). Male sex was an independent risk factor of POB on multivariate analysis (p < 0.01). LOS was significantly longer in patients who developed POB (8.3 vs. 3.8 days, p < 0.01). Management was conservative for most cases (68%). Eighteen patients with ILB (35%) and 5 patients with ELB (25%) required reoperation. One patient died from multiorgan failure after staple-line dehiscence of the excluded stomach (mortality 0.04%). CONCLUSION: The incidence of POB is low, yet it is the most frequent postoperative complication after RYGB. Most POB can be managed conservatively while surgical treatment is required for patients with hemodynamic instability or signs of intestinal obstruction due to an intraluminal clot. GRAPHICAL ABSTRACT: [Image: see text
Side-to-side magnet anastomosis system duodeno-ileostomy with sleeve gastrectomy: early multi-center results
No full textIntroduction: Gastrointestinal anastomoses with classical sutures and/or metal staples have resulted in significant bleeding and leak rates. This multi-site study evaluated the feasibility, safety, and preliminary effectiveness of a novel linear magnetic compression anastomosis device, the Magnet System (MS), to form a side-to-side duodeno-ileostomy (DI) diversion for weight loss and type 2 diabetes (T2D) resolution. Methods: In patients with class II and III obesity (body mass index [BMI, kg/m2] ≥ 35.0– ≤ 50.0 with/without T2D [HbA1C > 6.5%]), two linear MS magnets were delivered endoscopically to the duodenum and ileum with laparoscopic assistance and aligned, initiating DI; sleeve gastrectomy (SG) was added. There were no bowel incisions or retained sutures/staples. Fused magnets were expelled naturally. Adverse events (AEs) were graded by Clavien-Dindo Classification (CDC). Results: Between November 22, 2021 and July 18, 2022, 24 patients (83.3% female, mean ± SEM weight 121.9 ± 3.3 kg, BMI 44.4 ± 0.8) in three centers underwent magnetic DI. Magnets were expelled at a median 48.5 days. Respective mean BMI, total weight loss, and excess weight loss at 6 months (n = 24): 32.0 ± 0.8, 28.1 ± 1.0%, and 66.2 ± 3.4%; at 12 months (n = 5), 29.3 ± 1.5, 34.0 ± 1.4%, and 80.2 ± 6.6%. Group mean respective mean HbA1C and glucose levels dropped to 1.1 ± 0.4% and 24.8 ± 6.6 mg/dL (6 months); 2.0 ± 1.1% and 53.8 ± 6.3 mg/dL (12 months). There were 0 device-related AEs, 3 procedure-related serious AEs. No anastomotic bleeding, leakage, stricture, or mortality. Conclusion: In a multi-center study, side-to-side Magnet System duodeno-ileostomy with SG in adults with class III obesity appeared feasible, safe, and effective for weight loss and T2D resolution in the short term.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Global attitudes in the management of acute appendicitis during COVID-19 pandemic: ACIE Appy Study
No full textBackground: Surgical strategies are being adapted to face the COVID-19 pandemic. Recommendations on the management of acute appendicitis have been based on expert opinion, but very little evidence is available. This study addressed that dearth with a snapshot of worldwide approaches to appendicitis.
Methods: The Association of Italian Surgeons in Europe designed an online survey to assess the current attitude of surgeons globally regarding the management of patients with acute appendicitis during the pandemic. Questions were divided into baseline information, hospital organization and screening, personal protective equipment, management and surgical approach, and patient presentation before versus during the pandemic.
Results: Of 744 answers, 709 (from 66 countries) were complete and were included in the analysis. Most hospitals were treating both patients with and those without COVID. There was variation in screening indications and modality used, with chest X-ray plus molecular testing (PCR) being the commonest (19·8 per cent). Conservative management of complicated and uncomplicated appendicitis was used by 6·6 and 2·4 per cent respectively before, but 23·7 and 5·3 per cent, during the pandemic (both P < 0·001). One-third changed their approach from laparoscopic to open surgery owing to the popular (but evidence-lacking) advice from expert groups during the initial phase of the pandemic. No agreement on how to filter surgical smoke plume during laparoscopy was identified. There was an overall reduction in the number of patients admitted with appendicitis and one-third felt that patients who did present had more severe appendicitis than they usually observe.
Conclusion: Conservative management of mild appendicitis has been possible during the pandemic. The fact that some surgeons switched to open appendicectomy may reflect the poor guidelines that emanated in the early phase of SARS-CoV-2
