Oil pollution in the marine environment is an unavoidable problem due to chronic input from local sources, particularly in urban areas and oil spills. Oil pollution not only causes immediate physical damages to surrounding wildlife but also some components, including higher molecular weight PAHs, can persist in the environment for many years and pose insidious threats to the ecosystem. Long-term and nontargeted monitoring of oil pollution is important. This paper examines the ability of International Pellet Watch (IPW) for initial identification and monitoring of oil pollution by analysing PAHs and hopanes in plastic pellet samples collected globally by volunteers. PAH concentrations with the sum of 28 parent and methyl PAHs vary geographically, ranging from 0.035 to 24.4 µg/g-pellet, in line with the presence or absence of local oil pollution sources, such as oil refineries or oil spill sites. This suggests that PAHs can be used to monitor petroleum pollution in IPW. A colour-coded categorization for PAH concentrations within IPW monitoring also is established to facilitate data presentation and understanding. PAH concentrations are generally higher in Western Europe, especially around the North Sea shorelines, moderate in East Asia and North America, and lower in South East Asia, Oceania, South America, and Africa. Hopane concentrations, with a smaller spatial variation (1.7-101 µg/g-pellet), showed no spatial pattern. This result and the poor correlation between hopanes and PAHs suggest that hopane concentrations alone are unsuited to identify petroleum pollution. However, hopane compositions can be used for fingerprinting sources of oil pollution. Thus, both PAHs and hopanes in IPW allow for low cost, remote monitoring of global oil pollution.
Purpose: Thermal shrinkage of mouthguard sheet material influenced the thickness after forming. The aim of this study was to investigate the elongation and thickness of mouthguard sheets in relation to the thermal shrinkage of the mouthguard sheet material. Methods:Cross stripes (10×10 mm) were printed on mouthguard sheets. The length in the anteroposterior and bilateral direction was measured using vernier calipers, and the thickness of each cross stripe area was measured using a measuring device. The plaster cast was trimmed to the height of 20 mm at the upper central incisor and 15 mm at the upper first molar. The sheets were heated until they sagged 15 mm from the baseline. Two positions of the sheet were compared: the sheet became parallel (condition A) or vertical (condition B) direction to the thermal shrinkage of the mouthguard sheet material toward the cast. The difference in the ratio of change of the elongation and thickness between two conditions was analyzed by paired t-test and Wilcoxon signed-rank test. Additionally, the relationship between the elongation and thickness of the sheets was investigated by regression analysis. Results:The elongation in the part of the sheet fitted to the anterior teeth and posterior teeth of condition A was smaller than that of condition B. The thickness in the part of the sheet fitted to the palate and posterior teeth of condition A was smaller than that of condition B. The relationship between the elongation and thickness of mouthguard sheets was modeled by a quadratic equation. Conclusion: This study suggests that the thickness of the part of the sheet fitted to the palate and posterior teeth, which was parallel in direction to the thermal shrinkage of the mouthguard sheet material toward the plaster cast, was thinner than that of the vertical direction.
The adaptation to a high protein diet of the concentration and mRNA level of a trypsin-sensitive, cholecystokinin-releasing peptide (monitor peptide), which was proposed to be the mediator of the cholecystokinin release in response to protein intake, was investigated in the rat pancreas. Adult rats were placed on one of two isocaloric diets. One group was fed a 22% casein diet (control diet) and the other a 64% casein diet (high-protein diet) for 14 days. In order to quantify the monitor peptide separately from pancreatic secretory trypsin inhibitor (PSTI-11), which is highly similar in its amino acid and mRNA nucleotide sequences to the monitor peptide but has less cholecystokinin-releasing activity, we used specific assay methods: HPLC was used for determining the monitor peptide concentration in zymogen granules and a synthetic oligonucleotide probe for determining the mRNA of the monitor peptide in the pancreas. The concentrations in the zymogen granules and the mRNA levels in the pancreas of the two peptides increased in parallel during the adaptation to the high protein diet, indicating that these two peptides were under the same control during the adaptation. The concentration and mRNA level of the monitor peptide, which were measured after 0,3, and 14 days, increased throughout the experiment period, as did the concentration of trypsin. This suggested that the monitor peptide and trypsin may respond to similar signals during the adaptation to a high protein diet and that this apparent coordination may facilitate the adaptation of the pancreas to the diet.Prolonged high protein intake leads to increases in the concentrations [l] and mRNA levels [2] of proteases and decreases in those of amylase 11, 31 in the pancreas. Likewise, a lipid-rich diet causes a high content of Iipase [4] and an increase in its mRNA level [5] in the pancreas. This increase in the rate of pancreatic enzymes synthesis is a clever adaptation by the animal to a new diet.There is growing evidence that cholecystokinin (CCK) may be involved in the adaptative increase in pancreatic proteases in response to prolonged intake of a high protein diet [6 -81. The CCK-releasing level is regulated on the basis of a balance between secreted protease activity and the luminal food protein content [9]. Insufficient protease activity for the digestion of food protein in the lumen may cause a signal to be sent to the pancreas to promote the secretion and synthesis of proteases [lo, 111. The release of CCK is mediated by the CCK-releasing peptide (monitor peptide), which is synthesized in pancreas and secreted into the small intestine [9-171. This peptide is an essential factor for CCK secretion, because when it was absorbed with a specific antibody no more pancreatic enzyme secretion was observed in response to food protein intake [9]. Recently, Goke et al. [18] reported that the CCK response to protease inhibitor feeding was increased after the induction of Correspondence to
Carboxylic acids are found in almost all living organisms and are certainly indispensable compounds. They also play an important role in organic chemistry and hence are often utilized in their protective forms for two reasons: (1) The acidic proton of the carboxyl functional group (-COOH) can be masked by conversion to the corresponding esters and amides. (2) The carbonyl group of -COOH can be protected as oxazolines and ortho esters to prevent against nucleophilic attack and/or R-deprotonation. 1 However, the latter carbonyl protection has not been widely utilized due to the troublesome functional group transformation of multifunctional molecules. [2][3][4][5] Here we report that the bowlshaped tris(2,6-diphenylbenzyl)silyl (TDS) group can be successfully utilized as a new and highly effective protector of carboxylic acids against various nucleophilic attacks and R-deprotonation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.