Impact modifiers als high-tech toepassing van RAFT polymerisatie

Schokweerstand is één van de belangrijkste eigenschappen van een kunststof voor succesvol gebruik in allerlei toepassingen. Om de schokweerstand te boosten, kan een impact modifier (zie Figuur 1) in de vorm van core-shell nanodeeltjes toegevoegd worden aan kunststoffen. De productie van deze core-shell nanodeeltjes is echter niet vanzelfsprekend en vergt het gebruik van een gecontroleerde polymerisatietechniek, namelijk reversibele additie-fragmentatie ketentransfer (RAFT) polymerisatie, in emulsie. Als RAFT-specifiek reagens worden xanthaten aangewend. Ondanks een verminderde controle over de ketengroei, hebben xanthaten als specifiek voordeel dat ze oppervlakteactief zijn en daarom kunnen gebruikt worden voor de productie van core-shell nanodeeltjes

From catalyst to process : bridging the scales in modeling the OCM reaction

Process simulations for catalyzed reactions generally do not incorporate model equations based on the fundamentals of catalyst and reactor configuration. Yet, doing so could significantly enhance the reliability of predictions and designs. An easy-to-use solution to integrate catalyst-dependent kinetics into industrially-relevant reactor models within the environment of a process simulator is proposed and illustrated step-by-step for the Oxidative Coupling of Methane (OCM). A multi-stage adiabatic configuration with intermediate cooling and distributed oxygen feed is selected as case study. Results for three different OCM catalysts (Sn-Li/MgO, NaMnW/ SiO2, Sr/La2O3) revealed that a multi-stage configuration can be beneficial in terms of methane conversion and C2+ yield compared to a single stage. Remarkably, the addition of multiple stages led to more significant increases in yield for the more active but less selective Sr/La2O3 catalyst. For this catalyst, the impact of oxygen feed in the successive stages on the C2+ selectivity was found negligible. This was rationalized via a microkinetic contribution analysis of the prevailing oxidation routes, i.e. of methane (primary) and ethylene (consecutive). This case study highlights the importance of catalyst-tailored process evaluations of different scenarios for the industrial implementation of a complex chemical reaction such as OCM

Long-term Clinical Effectiveness of Ustekinumab in Patients with Crohn's Disease Who Failed Biologic Therapies: A National Cohort Study

BACKGROUND: Ustekinumab [UST] was recently approved in Europe for the treatment of moderate to severe Crohn's disease [CD]. Long-term real-world data are currently scarce for CD patients previously exposed to several biologics. METHODS: This is an observational, national, retrospective multicentre study. Patients received intravenous UST ~6 mg/kg at baseline, with 90 mg subcutaneously thereafter every 8 weeks. Response and remission rates were assessed at Weeks 8, 16, and 52. RESULTS: Data from 152 patients were analysed. All patients were exposed to at least one anti-TNFα agent, with 69.7% were exposed to even two anti-TNFα and vedolizumab. After 1 year, 42.1% and 25.7% of patients had experienced clinical response and clinical remission, respectively, and 38.8% and 24.3% had achieved steroid-free clinical response and remission, respectively; 38.8% of patients discontinued therapy during the 12 months of follow-up. Colonic location was predictive of clinical response at 1 year, and low body mass index [BMI] at baseline was a negative predictor of clinical remission. Resolution of arthralgia was associated with clinical response over time. De novo arthralgia was reported by 17.9% of patients at Week 8 and 13.5% of patients at Week 52. No impact of UST on arthralgia was observed in patients with concomitant ankylosing spondylitis [n = 17]. Others adverse events were reported in 7.2% of patients. CONCLUSIONS: This real-world cohort study confirms the effectiveness of UST in CD patients previously exposed to several biologics. Ustekinumab was well tolerated with respect to adverse events. PODCAST: This article has an associated podcast which can be accessed at https://academic.oup.com/ecco-jcc/pages/podcast.status: publishe

Long-term Clinical Effectiveness of Ustekinumab in Patients with Crohn's Disease Who Failed Biologic Therapies: A National Cohort Study.

BACKGROUND: Ustekinumab [UST] was recently approved in Europe for the treatment of moderate to severe Crohn's disease [CD]. Long-term real-world data are currently scarce for CD patients previously exposed to several biologics. METHODS: This is an observational, national, retrospective multicentre study. Patients received intravenous UST ~6 mg/kg at baseline, with 90 mg subcutaneously thereafter every 8 weeks. Response and remission rates were assessed at Weeks 8, 16, and 52. RESULTS: Data from 152 patients were analysed. All patients were exposed to at least one anti-TNFalpha agent, with 69.7% were exposed to even two anti-TNFalpha and vedolizumab. After 1 year, 42.1% and 25.7% of patients had experienced clinical response and clinical remission, respectively, and 38.8% and 24.3% had achieved steroid-free clinical response and remission, respectively; 38.8% of patients discontinued therapy during the 12 months of follow-up. Colonic location was predictive of clinical response at 1 year, and low body mass index [BMI] at baseline was a negative predictor of clinical remission. Resolution of arthralgia was associated with clinical response over time. De novo arthralgia was reported by 17.9% of patients at Week 8 and 13.5% of patients at Week 52. No impact of UST on arthralgia was observed in patients with concomitant ankylosing spondylitis [n = 17]. Others adverse events were reported in 7.2% of patients. CONCLUSIONS: This real-world cohort study confirms the effectiveness of UST in CD patients previously exposed to several biologics. Ustekinumab was well tolerated with respect to adverse events. PODCAST: This article has an associated podcast which can be accessed at https://academic.oup.com/ecco-jcc/pages/podcast