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Highly active MgP catalyst for biodiesel production and polyethylene terephthalate depolymerization
(2022)
A highly active heterogeneous catalyst was designed and employed for two relevant transesterification reactions. i. e. biodiesel production and depolymerization of polyethylene terephthalate (PET). The material was prepared in the presence of pectin by the co-precipitation method followed by calcination at 600°C (MgP). MgP is efficient for biodiesel production, with a yield of ≈99% in 6 h/65°C, and with a molar ratio methanol: oil of 21:1. The reference material (MgR, prepared in absence of pectin) showed a poor catalytic performance in the same experimental conditions. For the methanolysis of PET, 100% PET conversion was obtained with 3 wt% catalyst, 200:1 methanol: PET molar ratio at milder conditions 160°C/4 h, compared to a 33% conversion without the presence of a catalyst. The catalyst showed remarkable stability and negligible deactivation after five consecutive runs. Materials were characterized by SEM, XRD, IR, TGA, and BET.
The intelligent recycling of plastics waste is a major concern. Because of the widespread use of polyethylene terephtalate, considerable amounts of PET waste are generated that are ideally re-introduced into the material cycle by generating second generation products without loss of materials performance. Chemical recycling methods are often expensive and entail environmentally hazardous by-products. Established mechanical methods generally provide materials of reduced quality, leading to products of lower quality. These drawbacks can be avoided by the development of new recycling methods that provide materials of high quality in every step of the production cycle. In the present work, oligomeric ethylene terephthalate with defined degrees of polymerization and defined molecular weight is produced by melt-mixing PET with different quantities of adipic acid as an alternative pathway of recycling PET with respect to conventional methods, offering ecofriendly and economical aspects. Additionally, block-copolyesters of defined block length are designed from the oligomeric products.
Ethylene terephthalate and ethylene naphthalate oligomers of defined degree of polymerization were synthesized via chemical recycling of the parent polymers. The oligomers were used as defined building blocks for the preparation of novel block-co-polyesters having tailored sequence compositions. The sequence lengths were systematically varied using Design of Experiments. The dispersive surface energy and the specific desorption energy of the co-polymers were determined by inverse gas chromatography. The study shows that polyethylene terephthalate-polyethylene naphthalate (PET-PEN) block-co-polyesters of defined sequence lengths can be prepared. Furthermore, the specific and dispersive surface energies of the obtained block-co-polyesters showed a linear dependence on the oligomer molecular weight and it was possible to regulate and control their interfacial properties. In contrast, with the corresponding random-block-co-polyesters no such dependence was found. The synthesized block-co-polyesters could be used as polymeric modifying agents for stabilizing PET-PEN polymer blends.
The interfacial compatibility between polymers and nanoclay fillers as well as the thermostability of both components are important characteristics for processing them into polymer composites. While the polymer component is often grafted using common polymerization reactions, the nanoclay component is usually surface modified by surfactant treatment to improve compatibility. In the present study, the polymer ethylene vinyl alcohol and a nanoclay filler based on natural bentonite are both surface modified by different silanes, 3-glycidoxypropyltrimethoxysilane and methacryloxymethyltrimethoxysilane and their interfacial properties are investigated by inverse gas chromatography. The silane-modified samples had improved interfacial properties as reflected by a significant increase in dispersive and specific surface energies. Lewis acidities were determined using chloroform and 1,4-dioxane as polar probes and showed a good match between polymer and nanofiller interfaces. Lewis acidity was generally lower after silane-modification. Silanization yielded increased thermal stability of the treated samples. Thus, silanization led to improved compatibility and enhanced thermal stability which facilitates further processing.
Relocation of production to countries with low labour costs has induced increased labour market flexibility, which has been praised as a silver bullet for economic growth and low unemployment. Within a unionised oligopoly framework, in which a multinational firm has the option to relocate its production to a foreign country, we analyse the welfare implications of both centralised and flexible wage-setting regimes. For very low foreign wages, wage flexibility leads to higher welfare than a rigid centralised regime. In contrast, for ‘intermediate’ wage levels in the foreign country, an industry-wide uniform wage leads to higher social welfare than flexible wages.
A new two-dimensional fluorescence sensor system was developed for in-line monitoring of mammalian cell cultures. Fluorescence spectroscopy allows for the detection and quantification of naturally occurring intra- and extracellular fluorophores in the cell broth. The fluorescence signals correlate the the cells' current redox state and other relevant process parameters. Cell culture pretests with twelve different excitation wavelengths showed that only three wavelengths account for a vast majority of spectral variation. Accordingly, the newly developed device utilizes three high-power LEDs as excitation sources in combination with a back-thinned CCD-spectrometer for fluorescence detection.
Poly(dimethylsiloxane) can be covalently coated with ultrathin NCO-sP(EO-stat-PO) hydrogel layers which permit covalent binding of cell adhesive moieties, while minimizing unspecific cell adhesion on non-functionalized areas. We applied long term uniaxial cyclic tensile strain (CTS) and revealed (a) the preservation of protein and cell-repellent properties of the NCO-sP(EO-stat-PO) coating and (b) the stability and bioactivity of a covalently bound fibronectin (FN) line pattern. We studied the adhesion of human dermal fibroblast (HDFs) on non-modified NCO-sP(EO-stat-PO) coatings and on the FN. HDFs adhered to FN and oriented their cell bodies and actin fibers along the FN lines independently of the direction of CTS. This mechanical long term stability of the bioactive, patterned surface allows unraveling biomechanical stimuli for cellular signaling and behavior to understand physiological and pathological cell phenomenon. Additionally, it allows for the application in wound healing assays, tissue engineering, and implant development demanding spatial control over specific cell adhesion.
Plasma polymerization is used for the modification and control of surface properties of a highly transparent, thermoplastic elastomeric silicone copolymer, GENIOMER® 80 (G80). PEG-like diglyme plasma polymer films were deposited with ether retentions varying between 20% and 70% as measured by X-ray photoelectron spectroscopy analysis which did not affect the transparency of the substrate. Films with ether retentions of greater than 70% inhibit protein binding (bovine serum albumin and fibrinogen) and cell proliferation. A short oxygen plasma pretreatment enhances the adhesion and stability of the film as shown by protein binding and cell adhesion experiments. The transparency of the material and the stability of the coating makes this material a versatile bulk material for technical (e.g., lab-on-a-chip) and biomedical (e.g., intraocular lens) applications. The G80/plasma polymer composite is stable against vigorous washing and storage over 5 months and, therefore, offers an attractive alternative to poly(dimethylsiloxane).
AbstractThrough their procyclical behavior, loan loss provisions have been determined as one of the factors that contribute to financial instability during a crisis. IFRS 9 was introduced in 2018 with an expected credit loss model replacing the incurred loss model of IAS 39 to mitigate the effect in the future. Our study aims to analyze loan loss provisions of major banks in the Eurozone to determine for the first time if the implementation of IFRS 9, as intended by regulators, has a dampening effect on procyclicality, especially during the stressed situation under COVID‐19. We analyze 51 banks from 12 countries of the European Monetary Union using 2856 firm‐year observations. While no robust evidence of less procyclicality can be found after the implementation of IFRS 9 until the pandemic, we find evidence that loan loss provisions moved countercyclical during 2020, indicating an alleviating effect at the beginning of the exogenous shock.
Clinical development is historically the phase in which a potential new medicine is being tested in phase 2 and phase 3 patient trials to demonstrate the new molecules' efficacy and safety to support the regulatory approval of drugs by health authorities. This relatively focused approach has been considerably expanded by a number of forces from within the pharmaceutical industry and equally important by changes in the healthcare systems. The need to identify the optimal patient population, showstoppers leading to discontinuation of clinical programs, the silent but constant removal of surrogate endpoints for registration, and the increased demand for real-life data which are used to demonstrate the patients' benefit and which have an ever-increasing role for pricing and reimbursement negotiations are today an integral part of this phase.
This chapter will review both the nuts and bolts of clinical development but also recent developments in this area which shape the environment and how the different players have reacted and what options might need to be explored in the future.