177,096 research outputs found
Thromboxane synthase inhibitors suppress more effectively the aggregation of thromboxane receptor-desensitized than that of normal platelets. Role of adenylylcyclase up-regulation
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Aerobic Biodegradation at a Seawater-Sediment Interface of a New Bioplastic 100% Based on Natural Polymers
No full textBioplastics are a family of sustainable materials, trying to substitute for fossil-based plastic. Despite their growing expansion over the past decade, there are many scientific concerns about their biodegradability, especially if they are accidentally released into the environment. This is because biomass-based bioplastics are in general composed of blended polymers in which the blending material can come from fossil sources or cannot be biodegradable. Furthermore, the production of bioplastics (BPs) is generally made from first generation raw materials that represent food crops. This may generate critical ethical and environmental issues. To avoid these issues, in the last 20 years, many new materials have been developed starting from many different byproducts to valorize biomass. However, in most cases, the percentage of waste in the final BP formulation is very low since they are only added as additives to other BPs. Proteins are a family of natural polymers that have intrinsic plastic properties, so they can be produced without blending with other fossil-based polymers. In this work, a protein-based BP produced from milk (SP Milk®), already tested for biodegradability in soil and compostability in a home composter, was tested for biodegradability at the natural seawater-sediment interface according to ISO 19679:2020 measuring evolved CO2. The aim of this work is to acquire general and preliminary results regarding how much biodegradable a BP 100% based on natural polymers would be in a simulated marine ecosystem. This is very important in view of the recent EU directive in single-use plastics, which admits to this aim only materials based on natural polymers not chemically modified. Our results show that a hypothetical transient anoxia occurred at the beginning of the experiment and that an 83% biodegradation was achieved in 52 days. This adds fundamental information on the aquatic behavior of BPs based only on natural polymers, in particular proteins, which is totally lacking, and encourages the development of those kinds of materials
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Thromboxane does not play a significant role in acute, cold induced vasoconstriction in raynaud’s phenomenon
No full textPlatelet glycohydrolase activities: characterization and release
No full textGranules containing acid hydrolases have been detected in human platelets but have not been thoroughly characterized. We have studied the activity and characteristics of glycohydrolases present in normal human platelets, evaluated their release upon stimulation with thrombin, and assessed the contribution of platelet - released lysosomal contents to the glycohydrolase activity present in normal serum. Platelets contained a remarkable glycohydrolase activity with a prevalence of beta - N-acetylhexosaminidase. All glycohydrolases were released to some extent upon stimulation with thrombin and contributed to the glycohydrolase activity found in human serum. alpha-Mannosidase and alpha-galactosidase were partially inactivated after release by a mechanism as yet undefined. In addition, thrombin stimulation affects the intraplatelet isoenzyme pattern of beta-N-acetylhexosaminidase by producing the appearance of a new form
Model Based Engine Control Development and Hardware-in-the-Loop Testing for the EcoCAR Advanced Vehicle Competition
No full textAerobic biodegradation at seawater-sediment interface of a compostable and food waste-based bioplastic
No full textBioplastics are heterogeneous groups of material with multiple applications in different fields whose future production will increase more and more over the time. Currently their market presence in much lower than
those conventional because of production costs. Bioplastics available nowadays are produced using 1st generation feedstock and they could generate ethical end environmental critical issues related to soil
consumption not for human food production. Thus, efforts are made to develop these materials starting from waste, to increase their upstream sustainability reducing their production costs. [1] Another concern regard
their compostability because they are not always compostable under home composting conditions. This causes the same injuries produced by the environmental dispersion of conventional plastics. Therefore, the
present work was focused on the biodegradation in sea water of a bioplastic material produced By SPlastica srl ©, produced by expired milk and already tested for compostability according to EN 13432:2000. The
experiment was carried out in aerobic and controlled laboratory conditions according to ISO 19679:2020 and [2] to simulate the biodegradation at sediment-water interface in sublittoral coastal zone. The bioplastic milk based (SP-Milk) biodegradability was tested against positive control (filter paper), negative control (LDPE) and blank (seawater and sediment without any other material (blank). Its biodegradation percentage reaches, measuring the CO2 developed, the 83.5% in just 52 days with respect to the endogenous respiration rate represented by the blank. Only few gelatinous-like residues of samples remained and were analyzed by optical microscope. The biodegradation data were supported by visual disappearance of the sample and by optical microscopy results that reveal an intense microorganism presence at water-SP Milk residues interface. To the best of our knowledge, comparable results were not obtained yet in a so tiny timeframe and represents a promising first result for further studies on ecotoxicological effects on marine biota.
[1] https://docs.european bioplastics.org/publications/fs/EuBP_FS_Renewable_resources.pdf
[2] Briassoulis, Demetres & Pikasi, A. & Papardaki, N.G. & Mistriotis, Antonis. (2020). Aerobic biodegradation of bio-based plastics in the seawater/sediment interface (sublittoral) marine environment of the coastal zone – Test method under controlled laboratory conditions. Science of The Total Environment. 722. 137748. 10.1016/j.scitotenv.2020.137748
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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