Carbon dioxide (CO2) gas is the main contributor to climate change. CO2 storage in underground brines and oil‐field brines by mineral trapping has been considered as a promising alternative in order to reduce CO2 emissions. However, permanent storage of CO2 in stable carbonate minerals is greatly dependent on brine pH, being favored over an alkaline pH. The effect of alkaline additives (NaOH, KOH, CaO) and buffer solutions (NaHCO3/NaOH, Na2HPO4/NaOH, NH4Cl/NH4OH) on the mineral trapping of CO2 under mild conditions using a synthetic brine is investigated. The results indicate that both NaOH+NH4Cl/NH4OH and KOH+NH4Cl/NH4OH mixtures promote precipitation mainly of calcium carbonate (CaCO3). 相似文献
The development of new polymeric and polymeric based materials is fundamental to meet the market demands. This work aims the synthesis and characterization of polyurethane/titanium dioxide nanocomposite, using low cost commercial raw materials. Nanocomposites were synthesized by in situ polymerization reactions in which titanium dioxide were added in the following proportions, by weight, in relation to the mass obtained from the pure polymer: 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 10.0 %. These reactions were based in poli (ε-caprolactone) and 1,6-diisocyanatohexane. The materials were characterized by infrared spectroscopy Fourier transform, scanning electron microscopy, differential scanning calorimetry analysis, thermogravimetric analysis, dynamic mechanical thermal analysis, and UV–Vis spectroscopy. Based on the obtained results it was concluded that the nanocomposites synthesized by in situ polymerization presented, in general, thermal properties (degradation temperature) and mechanical properties higher than the pure polymer. 相似文献
The direct synthesis of dimethyl carbonate (DMC) using carbon dioxide as solvent and reagent for its fixation to methanol was explored with di-n-butyldimethoxystannane in order to get insight into the reaction mechanism for activity improvement. Catalytic runs including recycling experiments allowed isolation and characterization by NMR, IR, and single-crystal X-ray diffraction of a new tin complex containing 10 tin atoms. This compound could be prepared independently and is considered as a resting species. The yield of DMC is highest under 20 MPa pressure that fits with a monophasic supercritical medium in agreement with fluid phase equilibria calculations. In line, preliminary kinetics and initial rate determination show a positive order in carbon dioxide and a first-order dependence on the stannane. The initial rates were lower with the deca-tin complex than with the stannane precursor, but the turnover numbers (TONs) were higher. Water, the co-product of the reaction, was found to reversibly poison the active centers. Its in situ trapping had a beneficial effect. This study provides new mechanistic clues as to the reactive species and DMC formation. Further kinetics work is in progress to determine the rate-limiting step(s) at the initial stage of the reaction for more active catalyst design. 相似文献
Waterborne polyurethane (WPU) is receiving great attention in recent decades mainly due to the possibility of the replacement of organic solvents by the water. However, this change causes a decrease in the properties (mechanical, thermal, adhesion, among others) of the films obtained by this technique. Therefore, studies have been carried out in the development of polymeric matrix with the incorporation of inorganic fillers. This work presents the synthesis by the in situ polymerization technique and the characterization of waterborne polyurethane/ZnO composites. These composites were based on isophorone diisocyanate, 2,2-bis(hydroxymethyl) propionic acid and a polyester diol (MM = 1,000 g/mol). The filler–polymer interaction, chemical structure, morphology, thermal and mechanical properties of the WPU/ZnO composites were investigated by Fourier transform infrared spectroscopy, Ultraviolet–visible spectroscopy, Thermogravimetric analysis, Differential scanning calorimetry, Scanning electron microscopy and Tensile testing. The results showed an improvement in thermal and mechanical properties of the PU/ZnO composites when compared with pure PU as well as good homogeneity of the filler into the polymer matrix. 相似文献
As experience with peritoneal dialysis (PD) has improved and peritonitis rates have decreased, more patients are surviving for long periods on PD. Associated with this has been the recognition that there are unique complications of PD, specifically sclerosing syndromes and membrane failure that are most common in the long-term patient. Although anecdotal data would suggest that the long-term exposure to "bio-incompatable" fluids and or the occurrence of severe episodes of peritonitis are contributory in the pathogenesis of these diseases, cause and effect have not been proven. Normal peritoneal structure, changes that occur over time, and how the normal resident immune defense systems are altered with PD are reviewed. It is known that the continued loss of macrophages in the PD fluid results in an ever increasing percentage of immature cells in the peritoneum, which paradoxically are more reactive in terms of cytokine generation and less effective in host defense. The potential harmful effects of glucose and advanced glycosylation end products are also explored. The review concludes stating that further research is needed to better link the clinical syndromes with alterations in membrane structure/function. 相似文献
Polypropylene (PP) has been widely used industrially in several sectors, mainly in the use of packaging of different products. Thus, this has been accumulated in our environment due to the incorrect disposal and its high resistance toward degradation, causing an array of environmental impacts. With this, one alternative that has been explored to minimize the problems intensified by these residues is the use of pro-degrading additives. Therefore, the aim of this work is to evaluate the degradation process of PP blends in soil using enzymatic additive. The soil degradation experiment was done for 6 months; monthly collected samples were checked for alterations on the material properties during that time. The extent of PP degradation with enzymatic additive was compared to an organic additive by techniques of FTIR, TGA, DSC, carbonyl index (CI), and crystallinity. From the obtained results it was observed that the additives influenced the degradation of PP. In addition, the enzymatic additive caused more significant changes in the CI (increase of 3693%), crystallinity (variation of 18.7%), and structural characteristics, indicating a greater influence on the degradation process in relation to the organic additive. In this way, this work has had an important role in the research and development of biodegradable materials with the aim of minimizing the effects induced by plastic waste in the environment.
Humans are the product of biologic and cultural adaptation to our Planet achieved over million years of Primates and Hominids
species evolution which has led us to a specific development of intelligence, speech, and manual capability. Interface usability
mainly depends on human characteristics that are also modified by variations in the environment. In outer space, body shapes
may be different, things may not be in the expected place and models of conventional social relationships may be hardly transferred
to prolonged missions. The process known as exaptation, according to which traits developed by a species as a response to a specific need are later “recycled” with new functions
in a different environment, will be considered. Biologic and cultural built-in mechanisms belonging to our past cannot be
left out in the analysis of design and man–machine interface in the Outer Space. 相似文献
Water treatment system and dialysis monitors are susceptible to microbial contaminations and periodical disinfection procedures are mandatory to obtain results requested from international standards and guidelines. Several chemical germicides or some physical treatments are on the market validated by device manufacturer according to medical device directives. With time, interfering substances from dialysis device or water are able to modify disinfection efficiency. Simulating-use testing is not a common procedure to validate disinfectants and recent data document as biofilm represents the most important cause of disinfection inefficacy. Some international standards include tests in the presence of various interfering substances but their use is not widespread. When using a disinfectant, residue toxicity, material compatibility and potential risks for the staff also have to be considered. A quality assurance program has to be implemented to obtain adequate performances and to improve results on patients. 相似文献