161 research outputs found
Promising tensile mechanical properties of the flax fibre reinforced vitrimer matrix composites – seeking sustainable opportunities for automotive
No full textunder the agreement number 451-03-137/2025-03/200105
AUTHOR CONTACT
Milan Jankovic, MSc
email: [email protected]
Promising tensile mechanical properties of the flax fibre reinforced vitrimer matrix composites – seeking sustainable opportunities for automotive
No full textunder the agreement number 451-03-137/2025-03/200105
AUTHOR CONTACT
Milan Jankovic, MSc
email: [email protected]
SAFE EXTUBATION AND REINTUBATION IN OPERATORY ROOM AND ICU PATIENTS
No full textEach intubation should result in an extubation at end of procedure, and each extubation, theoretically, could represent a potential reintubation due
to extubation manoeuvre failure. There are many and different reasons for extubation to fail, starting from mechanical iatrogenic lesions due to difficult intubation up to patient’s inhability to sustain spontaneous breathing and unassisted ventilation, going through extubation associated respiratory and cardiovascular complications, local mechanic or
inflammatory factors, surgical techniques and accidental events. Recent literature has clearly shown that if critical events associated with difficult intubation have lower
incidence thanks to guidelines diffusion and implementation, extubation related accidents did not change incidence and consequences in last couple of decades. This observation has led to developement of dedicated extubation guidelines and to attention from Scientific Community to promote culture of safety and anticipation, with predicted difficult extubation concept and protected extubation strategies, by using pharmacological and technical approach. Aim of this paper is to review data for extubation related accidents, to provide overview with existing guidelines and description of approaches to predict difficult extubation, techniques to provide best extubation
strategies including pharmacologic, non pharmacologic and instrumental techniques
Nondestructive determination of drying deformations in cement paste by means of ESEM and digital image analysis
No full textNovel modifications of an environmental scanning electron microscope (ESEM) were made in order to measure the local deformations in drying cement paste. These nondestructively determined moisture-induced plane strains, obtained in 1 mm thick cement paste samples, are orthotropic. They vary with variations of relative humidity between 70%-80% and 40%-50%, being the highest at 20% RH. Both drying shrinkage and expansion of cement paste microstructure occur in early-age and mature samples. Microcracking due to moisture gradient could not be avoided, although very thin samples were examined with gradual reduction of relative humidity in drying steps of 10%. The coefficient of deformation of cement paste is directly proportional to shrinkage/expansion. It depends on variations of relative humidity during drying in ESEM and the sample age.Micro Mechanic LaboratoryCivil Engineering and Geoscience
ESEM drying tests: Microcracking initiation in thin cement paste due to early age drying
No full textScattered and discontinues microcracking as a subsequent side-effect of deformations due to early age drying, occurs in thin (approximately 1 mm thick) cement paste samples, when stepwise dried in ESEM. Microcracking of cement paste and restrains appear to be practically unavoidable. They are related to a phenomenon of interfaces (‘matrix’ and ‘inclusion’), which exists at every scale. The combined effects of sample age, curing conditions and w/c ratio, influence development of microstructure at an early age as well as appearance of microcracks and their width (0.1-2.5 ?m). However, rapid change of environmental conditions in cycles of drying-wetting induces full fracture of thin cement paste samples, regardless of the mentioned effects.Structural EngineeringCivil Engineering and Geoscience
Study of ‘real’ shrinkage by ESEM observations and digital image analysis
No full textDefining the 'real' shrinkage values of concrete is still a subject of much debate. In shrinkage experiments size effects are inherently present. Through an attempt to determine the real shrinkage of cement-based materials, these size effects have to be eliminated or at least reduced as much a possible. In this contribution drying shrinkage experiments on thin cement paste samples are discussed. Thin-cast Portland cement paste specimens (2 mm) are used, polished to 1 mm with specially designed tools. Samples with and without aggregate inclusions (glass pearls) are considered. The specimens are dried in Environmental Scanning Electron Microscope (ESEM) from 100% to 20% relative humidity (RH). ESEM images are acquired during drying and analyzed by means of Digital Image Analysis. Both drying shrinkage and microcracking are determined. The analyses show a non-linear relation between RH and shrinkage deformations in the whole drying range (from 100% to 20%).Structural EngineeringCivil Engineering and Geoscience
Moisture flow and microstructure development of the interface zone
No full textDesign & ConstructionCivil Engineering and Geoscience
Enhanced hot-liquid water pretreatment of biomass with recovery and valorization of side products
No full textLignocellulosic biomass potentially represents a great feedstock for biofuel production, but its’ pretreatment needs to be enhanced in order to make biorefineries competitive with fossil fuel based alternatives. One way to make biorefineries more economically viable is to recover and valorize all generated by-products during the biomass pretreatment step. The main goal of this original research is to design an optimal process for recovering valuable by-products after hot-liquid water pretreatment of poplar biomass. Rigorous models for all operations included in the recovery process are developed using Aspen Plus as a CAPE tool. An optimal downstream processing sequence, consisting of multiple distillation steps, is designed to recover several valuable components, such as acetic acid, formic acid, furfural and 5-hydroxymethylfurfural (HMF).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Bioprocess EngineeringChemE/Product and Process Engineerin
A perspective on downstream processing performance for recovery of bioalcohols
No full textEven though industrial biotechnology is successfully used for the production of some chemicals, for many other chemicals it is not yet competitive with conventional petrochemical production. Usually, fermentation as well as downstream processing requires improvement. Downstream processing has to deal with low product concentrations, microorganisms, impurities and thermodynamic constraints (e.g., azeotropes), which often makes it very challenging and expensive, especially on a large scale. However, downstream processing of biochemicals has not attracted as much attention as upstream fermentation processes. In that context, this perspective paper offers a lightly referenced scholarly opinion about the downstream processing performance of different bioalcohols after fermentation. Due to the stronger toxicity effects on microbes, the achievable concentrations of monohydric aliphatic alcohols in the fermentation broth decrease with the increasing chain length. Specifically, the concentrations used here are 6.14, 5.00, 1.61 and 0.24 wt% of ethanol, isopropanol, isobutanol and hexanol, respectively. More dilute fermentation broths lead to more complex recovery processes. According to our previous work, the total purification costs increase from 0.080 USD kg−1 for ethanol, 0.109 USD kg−1 for isopropanol and 0.161 USD kg−1 for isobutanol to 0.529 USD kg−1 for hexanol. A similar trend is noticeable for the energy usage (0.960, 1.348, 2.018 and 3.069 kWthh kg−1, respectively) and the related CO2 emissions (0.164, 0.221, 0.449 and 0.555 kgCO2 kg−1, respectively). This work shows that advanced separation and purification based on process intensification principles are crucial for overall efficient production processes. The achievable product concentration in the fermentation broth – and not so much the alcohol chain length – has the biggest influence on the performance of downstream processing. Therefore, simultaneous development of both upstream and downstream processing is necessary to ensure the competitiveness and viability of industrial fermentation processes. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).BT/Bioprocess EngineeringChemE/Process Systems Engineerin
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