532 research outputs found

    A coating from nature

    Get PDF
    For almost a century, petrochemical-based monomers like acrylates have been widely used as the basis for coatings, resins, and paints. The development of sustainable alternatives, integrating the principles of green chemistry in starting material, synthesis process, and product function, offers tremendous challenges for science and society. Here, we report on alkoxybutenolides as a bio-based alternative for acrylates and the formation of high-performance coatings. Starting from biomass-derived furfural and an environmentally benign photochemical conversion using visible light and oxygen in a flow reactor provides the alkoxybutenolide monomers. This is followed by radical (co) polymerization, which results in coatings with tunable properties for applications on distinct surfaces like glass or plastic. The performance is comparable to current petrochemical-derived industrial coatings

    Contribution to a ranking procedure for polymeric caotings and hydrophobic agents for concrete

    Get PDF
    One of the possible ways to protect the concrete is using coatings and hydrophobic agents that act as a barrier against the environment. When selecting the material for concrete protection, importance should be given to these properties of diffusion and permeability. The coatings and the hydrophobic agents must stop the penetration of water and delay the influence of aggressive agents, allowing the structure to breathe by a water vapour diffusion mechanism. An evaluation of the surface layer transport properties gives information on the durability of a particular concrete. In order to make the selection of coatings and hydrophobic agents for concrete protection, it is important to analyse the compoundā€™s technical and economical performances. A ranking procedure, developed by Czarnecki and Lukowski, is applied on a series of concrete protection products. The ranking procedure is applied to evaluate durability experiments, carried out on some commercially available silicone, acrylic and epoxy compounds for surface treatment of concrete. The ranking procedure transforms experimental data of properties into one numerical value, by which the products can be classified according to the way on which their properties present an optimised or even best buy combination. The paper shows the use of the ranking procedure methodology, and points at the importance of the choice of the criteria and of their relative weight factor in the evaluation. The method is a valuable tool for the ranking of similar materials, whose performance is based on the same or similar physical or chemical processes

    Increasing repeat chlamydia testing in Family Planning clinics depends on perception of value and availability of low-burden flexible reminder systems.

    Get PDF
    Reā€infection after a chlamydia infection is common: 22% of young Australian women are reā€infected within 4ā€5months (Walker, et al, 2012). Reā€infections increase the risk of pelvic inflammatory disease (PID) by 4ā€6 fold (Bowring, et al, 2011). Retesting is an important strategy to detect reā€infection. Clinical guidelines note that repeat testing at least three months after a positive diagnosis be considered. AIM: To understand Australian Family Planning cliniciansā€™ practices and perceptions of repeat chlamydia testing.CONCLUSION: Reminder systems to support repeat testing of positive chlamydia tests had been implemented in some FPCs, with low workload impact. It was too early for evaluation of clinical success. These FPCs could share locally developed systems and positive experiences with FPCs skeptical about their value. This may also enhance awareness of the clinical value of retesting and the consequences of reā€ infection. Audits may help determine if clients are indeed being caught through repeat visits and opportunistic testing

    Increasing repeat chlamydia testing in Family Planning clinics depends on perception of value and availability of low-burden flexible reminder systems.

    Get PDF
    Reā€infection after a chlamydia infection is common: 22% of young Australian women are reā€infected within 4ā€5months (Walker, et al, 2012). Reā€infections increase the risk of pelvic inflammatory disease (PID) by 4ā€6 fold (Bowring, et al, 2011). Retesting is an important strategy to detect reā€infection. Clinical guidelines note that repeat testing at least three months after a positive diagnosis be considered. AIM: To understand Australian Family Planning cliniciansā€™ practices and perceptions of repeat chlamydia testing.CONCLUSION: Reminder systems to support repeat testing of positive chlamydia tests had been implemented in some FPCs, with low workload impact. It was too early for evaluation of clinical success. These FPCs could share locally developed systems and positive experiences with FPCs skeptical about their value. This may also enhance awareness of the clinical value of retesting and the consequences of reā€ infection. Audits may help determine if clients are indeed being caught through repeat visits and opportunistic testing

    Effect of paracetamol (acetaminophen) and ibuprofen on body temperature in acute ischemic stroke PISA, a phase II double-blind, randomized, placebo-controlled trial [ISRCTN98608690]

    Get PDF
    BACKGROUND: Body temperature is a strong predictor of outcome in acute stroke. In a previous randomized trial we observed that treatment with high-dose acetaminophen (paracetamol) led to a reduction of body temperature in patients with acute ischemic stroke, even when they had no fever. The purpose of the present trial was to study whether this effect of acetaminophen could be reproduced, and whether ibuprofen would have a similar, or even stronger effect. METHODS: Seventy-five patients with acute ischemic stroke confined to the anterior circulation were randomized to treatment with either 1000 mg acetaminophen, 400 mg ibuprofen, or placebo, given 6 times daily during 5 days. Treatment was started within 24 hours from the onset of symptoms. Body temperatures were measured at 2-hour intervals during the first 24 hours, and at 6-hour intervals thereafter. RESULTS: No difference in body temperature at 24 hours was observed between the three treatment groups. However, treatment with high-dose acetaminophen resulted in a 0.3Ā°C larger reduction in body temperature from baseline than placebo treatment (95% CI: 0.0 to 0.6 Ā°C). Acetaminophen had no significant effect on body temperature during the subsequent four days compared to placebo, and ibuprofen had no statistically significant effect on body temperature during the entire study period. CONCLUSIONS: Treatment with a daily dose of 6000 mg acetaminophen results in a small, but potentially worthwhile decrease in body temperature after acute ischemic stroke, even in normothermic and subfebrile patients. Further large randomized clinical trials are needed to study whether early reduction of body temperature leads to improved outcome

    Effect of paracetamol (acetaminophen) and ibuprofen on body temperature in acute ischemic stroke PISA, a phase II double-blind, randomized, placebo-controlled trial [ISRCTN98608690]

    Get PDF
    BACKGROUND: Body temperature is a strong predictor of outcome in acute stroke. In a previous randomized trial we observed that treatment with high-dose acetaminophen (paracetamol) led to a reduction of body temperature in patients with acute ischemic stroke, even when they had no fever. The purpose of the present trial was to study whether this effect of acetaminophen could be reproduced, and whether ibuprofen would have a similar, or even stronger effect. METHODS: Seventy-five patients with acute ischemic stroke confined to the anterior circulation were randomized to treatment with either 1000 mg acetaminophen, 400 mg ibuprofen, or placebo, given 6 times daily during 5 days. Treatment was started within 24 hours from the onset of symptoms. Body temperatures were measured at 2-hour intervals during the first 24 hours, and at 6-hour intervals thereafter. RESULTS: No difference in body temperature at 24 hours was observed between the three treatment groups. However, treatment with high-dose acetaminophen resulted in a 0.3Ā°C larger reduction in body temperature from baseline than placebo treatment (95% CI: 0.0 to 0.6 Ā°C). Acetaminophen had no significant effect on body temperature during the subsequent four days compared to placebo, and ibuprofen had no statistically significant effect on body temperature during the entire study period. CONCLUSIONS: Treatment with a daily dose of 6000 mg acetaminophen results in a small, but potentially worthwhile decrease in body temperature after acute ischemic stroke, even in normothermic and subfebrile patients. Further large randomized clinical trials are needed to study whether early reduction of body temperature leads to improved outcome

    The Diagnostic Accuracy of Serum Alpha-Fetoprotein Levels in Follow-up for Recurrence of Sacrococcygeal Teratoma; a Nationwide Review of SCT Cases in the Netherlands

    Get PDF
    Background:Ā Serum alpha-fetoprotein (AFP) is often used as tumour marker for recurrent sacrococcygeal teratoma (SCT). We aimed to assess the normal dynamics of serum AFP levels after initial resection and diagnostic accuracy of serum AFP levels the follow-up for recurrence in SCT.Ā Methods:Ā This retrospective study included 57 patients treated for SCT in the six pediatric surgical centers in the Netherlands from 1980 to 2018.Ā Main results:Ā 57 patients were included in the study of whom 19 children developed 20 recurrences at a median of 14.0 months after initial resection. No significant difference was found in serum AFP level dynamics between the recurrence and non-recurrence group after initial resection (p = 0.950). Serum AFP levels did not significantly increase before recurrence (p = 0.106) compared to serum AFP levels of children without recurrence at the same time. However, serum AFP levels did significantly increase in malignant recurrences (n = 7) (p = 0.03) compared to patients without recurrence. A cut-off value of 55 Ī¼g/L was found to be predictive for recurrent SCT with an Area Under the Curve (AUC) of 0.636 with sensitivity of 50% and specificity of 100%.Ā Conclusion:Ā Dynamics of serum AFP levels are not different between patients with and without recurrence after initial resection of SCT. Serum AFP levels are not predictive for mature or immature recurrent SCT and normal AFP levels do not rule out recurrent SCT. However, serum AFP levels exceeding 55 Ī¼g/L can indicate recurrent SCT, especially malignant recurrences.</p

    Asthma in 9-year-old children of subfertile couples is not associated with in vitro fertilization procedures

    Get PDF
    Asthma is a chronic reversible obstructive airway disease, which is common among children and leads to respiratory impairment. Studies showed that asthma is more common among children born after in vitro fertilization (IVF) than among spontaneously conceived children. However, it is unknown which component of the IVF procedure contributes to this putative link. Therefore, the aim of this prospective follow-up study was to differentiate the possible effect of ovarian hyperstimulation from that of the in vitro culture procedure on asthma and rhinitis in 9-year-old children conceived with IVF. The study comprised three groups of singletons: (I) conceived with ovarian hyperstimulation-IVF (COH-IVF, nā€‰=ā€‰95); (II) conceived with modified natural cycle-IVF (MNC-IVF, nā€‰=ā€‰48); and (III) naturally conceived to subfertile couples (Sub-NC, nā€‰=ā€‰68). Parents filled out the validated Dutch version of the asthma questionnaire of the International Study of Asthma and Allergies. Asthma prevalence in the groups did not differ: COH-IVF nā€‰=ā€‰8 (8%); MNC-IVF nā€‰=ā€‰0 (0%); and Sub-NC nā€‰=ā€‰4 (6%). Adjustment for confounders did not alter the results.Conclusion: Neither ovarian hyperstimulation nor the in vitro culture procedure was associated with asthma and rhinitis at 9 years. IVF children had a similar prevalence of asthma compared with children conceived naturally by subfertile couples.Trial registration: ISRCTN76355836 What is Known: ā€¢ An increased risk for asthma has been observed in children born after in vitro fertilization at preschool and school age. ā€¢ The association between IVF and asthma may be partly explained by parental subfertility. What is New: ā€¢ IVF children do not have a higher prevalence of asthma than children of subfertile couples conceived naturally. ā€¢ Ovarian hyperstimulation used in IVF is not associated with asthma in 9-year-old children of subfertile couples.</p

    <i>In situ</i> EPR and Raman spectroscopy in the curing of bis-methacrylate-styrene resins

    Get PDF
    The curing of bis-methacrylate-styrene resins initiated by the cobalt catalyzed decomposition of cumyl hydroperoxide is monitored at ambient temperatures in situ by EPR and Raman spectroscopy. EPR spectroscopy shows the appearance of organic radicals after ca. 1 h from initiation with an increase in intensity from both polystyrene and methacrylate based radical species over a further ca. 2 h period to reach a maximum spin concentration of ca. 2-3 mM. Alkene conversion to polymer was monitored by Raman spectroscopy in real time in situ with EPR spectroscopy and reveals that the appearance of the radical signals is first observed only as the conversion approaches its maximum extent (70% at room temperature), i.e., the resin reaches a glass-like state. The radicals persist for several months on standing at room temperature. Flash frozen samples (77 K) did not show EPR signals within 1 h of initiation. The nature of the radicals responsible for the EPR spectra observed were explored by DFT methods and isotope labelling experiments (D8-styrene) and correspond to radicals of both methacrylate and polystyrene. Combined temperature dependent EPR and Raman spectroscopy shows that conversion increases rapidly upon heating of a cured sample, reaching full conversion at 80 Ā°C with initially little effect on the EPR spectrum. Over time (i.e. subsequent to reaching full conversion of alkene) there was a small but clear increase in the EPR signal due to the methacrylate based radicals and minor decrease in the signal due to the polystyrene based radicals. The appearance of the radical signals as the reaction reaches completion and their absence in samples flash frozen before polymerization has halted, indicate that the observed radicals are non-propagating. The formation of the radicals due to stress within the samples is excluded. Hence, the observed radicals are a representative of the steady state concentration of radicals present in the resin over the entire timespan of the polymerization. The data indicate that the lack of EPR signals is most likely due to experimental aspects, in particular spin saturation, rather than low steady state concentrations of propagating radicals during polymerization.</p
    • ā€¦
    corecore