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Only Slight Differences (only + slight_difference)
Selected AbstractsElectron ionization mass spectra of phosphorus-containing heterocycles.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2006The electron ionization mass spectra of 27 cis - and trans -annelated 1,4,4a,5,6,7,8,8a-octahydro-2H -3,1,2-benzoxazaphosphinine 2-oxides were recorded to clarify the effects of the ring heteroatom (O or N), ring annelation, the P configuration and the substituents attached to the ring or to the N and P atoms. For compounds 1,12 different alkyl radical and alkene losses and the cleavage of the P,heteroatom bonds, instead of the P,C bonds, were representative and dependent mainly on the substitution on the N and P atoms. The replacement of Ph and OPh by N(CH2CH2Cl)2 on the P atom had a dramatic influence on the fragmentation process: new fragment ions were obtained and very little M+. (1,3%) was formed. Only slight differences were found between some of the corresponding isomers, but interestingly the compounds formed clear groups on the basis of the differences in their fragmentation, depending on the ring-N and ring-P substituents. Copyright © 2006 John Wiley & Sons, Ltd. [source] Toxicokinetics of sediment-associated polybrominated diphenylethers (flame retardants) in benthic invertebrates (Lumbriculus variegatus, oligochaeta)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2004Matti T. Leppänen Abstract Polybrominated diphenylethers (PBDEs) are ubiquitous environmental contaminants showing rapid temporal increase in some sample types. The compounds are known to biomagnify in aquatic food webs and are assumed to archive into sediments and soils. Currently, no direct evidence indicates whether sediment-associated PBDEs are available for biota. The aim of the present study was to explore the uptake and elimination of two common congeners (47 and 99) in sediment-inhabiting invertebrates to shed light on possible bioavailability of sediment-associated PBDEs. Two clean lake sediments were spiked with environmentally relevant concentrations of 14C-labeled tetra- and pentabromo diphenylether, and oligochaetes (Lumbriculus variegatus) were exposed for three or four weeks to allow kinetic accumulation calculations. Subsequent depuration tests were performed after three weeks of exposure to obtain depuration rates. Both congeners were clearly bioavailable, and only slight differences in steady-state tissue concentrations were found between the four sediment-ingesting oligochaete treatments (biota sediment accumulation factors [BSAFs], 3.0,3.7). The tetrabromo diphenylether-exposed oligochaetes that did not ingest sediment had clearly lower influx rates (0.1 vs 1,3 nmol h -1) than sediment-ingesting worms. Also, the estimated BSAF (1.8) was statistically different from that of the sediment-ingesting oligochaetes. These findings support the significance of feeding behavior in bioaccumulation of very hydrophobic organic contaminants. Depuration of both congeners was biphasic, indicating two kinetically different compartments in L. variegatus. Compartment A made up 73 to 92% of total radioactivity in tissues and had relatively fast depuration rates (half-lives, 10.5,47.5 h); the smaller compartment B had very slow depuration rates. No significant biotransformation of PBDEs was evident. The present study clearly demonstrates that the sediment-associated PBDEs, like other hydrophobic organic contaminants of environmental concern, are not totally sequestered from sediment-inhabiting oligochaetes and are subject to trophic transfer. [source] Seed characters and testa sculptures of some Iranian Allium L. species (Alliaceae)FEDDES REPERTORIUM, Issue 5-6 2009Fatemeh Neshati Seeds taken from herbarium specimens of 20 Allium taxa were investigated. The seeds of all species were black ranging from 1.7 mm (A. lamondiae) to 4 mm (A. altissimum and A. stipitatum) in length and 1 mm (A. lamondiae) to 3 mm (A. altissimum) in width. So, A. lamondiae had the smallest and A. altissimum the largest seeds. In the mean, the members of subg. Melanocrommyum had somewhat larger and the species of sect. Avulsea somewhat smaller seeds than most species belonging to other groups. The shape was generally ovate or variants of it and showed only slight differences between members of different sections. The seed coat pattern was more variable. Most common were convex, granulate periclinal walls bearing several verrucae. Only A. borszczowii showed flat, densely granulate periclinal walls without verrucae, and A. bungei and A. joharchii had somewhat verruca-like aggregating grana. The majority of the species investigated showed S-like, rarely Omega-like, undulated anticlinal walls with variable wavelengths and amplitudes. The testa cells of A. joharchii showed transitions to straight anticlinal walls. More or less straight anticlinal walls in A. kopetdagense, A. paradoxum, A. barsczewskii, and A. scabriscapum were connected with the presence of a strip-like widened and transversally striated intercellular region covering these walls. The seed coat pattern of most species corresponded well to earlier reports of the same or closely related species, or was at least already reported for not related Allium species. Only A. borszczowii and A. monophyllum displayed testa types earlier not reported. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Analysis of suspended sediment yields after low impact forest harvestingHYDROLOGICAL PROCESSES, Issue 26 2007Norifumi Hotta Abstract Disturbances to forest catchments have profound effects on the environment of headwater streams and have an impact on suspended sediment (SS) management. Forest harvesting is a dominant factor in increasing SS yields. Road construction, skidder activity and ploughing associated with harvesting cause serious soil disturbance that results in SS increases. However, few studies have shown whether harvesting itself increases SS yields. This study examined how harvesting influenced SS yields in a steep forested area. During harvesting, soil surface disturbance was prevented as much as possible by using skyline logging treatments and piling branches and leaves at selected locations in the watershed. Using these methods, the representative SS rating curve did not change significantly after harvesting. The results also show that the characteristics of SS transport were related to the SS source area, and reveal that the riparian zone/stream bank was a dominant SS source area at the study site. Annual SS yields did not increase despite increasing annual water yields after harvesting. The limited water capacity of the soil at the study site likely led to only slight differences in pre- and post-harvest water discharge from heavy rainfall events. Most SS was transported during heavy rainfall events, and increases in SS yields were not detected after harvesting. We concluded that it is possible to prevent post-harvest SS increases by performing careful, low-impact harvesting procedures. Copyright © 2007 John Wiley & Sons, Ltd. [source] A Comparison of Statistical Approaches for Predicting Stream Temperatures Across Heterogeneous Landscapes,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2009Kevin E. Wehrly Abstract:, Estimating stream temperatures across broad spatial extents is important for regional conservation of running waters. Although statistical models can be useful in this endeavor, little information exists to aid in the selection of a particular statistical approach. Our objective was to compare the accuracy of ordinary least-squares multiple linear regression, generalized additive modeling, ordinary kriging, and linear mixed modeling (LMM) using July mean stream temperatures in Michigan and Wisconsin. Although LMM using low-rank thin-plate smoothing splines to measure the spatial autocorrelation in stream temperatures was the most accurate modeling approach; overall, there were only slight differences in prediction accuracy among the evaluated approaches. This suggests that managers and researchers can select a stream temperature modeling approach that meets their level of expertise without sacrificing substantial amounts of prediction accuracy. The most accurate models for Michigan and Wisconsin had root mean square errors of 2.0-2.3°C, suggesting that only relatively coarse predictions can be produced from landscape-based statistical models at regional scales. Explaining substantially more variability in stream temperatures likely will require the collection of finer-scale hydrologic and physiographic data, which may be cost prohibitive for monitoring and assessing stream temperatures at regional scales. [source] Perceptions and practices on the management of gastro-oesophageal reflux disease: results of a national survey comparing primary care physicians and gastroenterologistsALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2007J.-F. BRETAGNE Summary Background Literature comparing generalist and specialist care is accumulating in many disease areas, but very few studies focussed on gastrointestinal diseases and little is known about gastro-oesophageal reflux disease. Aim To compare the management of gastro-oesophageal reflux disease (GERD) by French primary care physicians and gastroenterologists. Methods A postal survey was conducted in a representative sample of French physicians who were asked to complete a questionnaire that consisted of 44 questions relating to their usual medical practice for the diagnostic and therapeutic management of frequent GERD. Results 136 primary care physicians and 91 gastroenterologists participated in the survey (54%). Alarm symptoms were identified more frequently by primary care physicians than gastroenterologists, but the appraisal of their seriousness was less acute by primary care physicians than gastroenterologists. Upper endoscopy was prescribed more frequently by gastroenterologists (64% vs. 38%, P < 0.01). Physicians in both groups mainly recommended lifestyle modification. For GERD treatment, most respondents declared using a ,step-down' strategy with proton pump inhibitors, and only slight differences in drug prescription were identified between primary care physicians and gastroenterologists. Both groups of physicians also have similar perception of symptom persistence after treatment, but satisfaction with treatments was slightly higher for gastroenterologists than primary care physicians (7.6 vs. 7.1 on a scale from 0 to 10, P < 0.01). Conclusions Overall patterns of GERD diagnosis and management are comparable between primary care physicians and gastroenterologists. Both groups perceive that GERD therapy can still be improved. [source] Strategies providing success in a variable habitat: III.PLANT CELL & ENVIRONMENT, Issue 8 2001Dynamic control of photosynthesis in Cladophora glomerata Abstract Diurnal patterns of photosynthesis were studied in July and April populations of Cladophora glomerata (L.) Kütz. from open and from shaded sites. Summer samples exposed to full sunlight showed decreased efficiency of open photosystem II at noon, and only slight differences were found between samples that had grown at open or at shaded sites. Electron transport rate was limited at highest fluence rates in shade plants, and non-photochemical quenching (NPQ) revealed faster regulation in samples from open sites. Daily course of de-epoxidation was not linearly correlated with the course of NPQ. The comparison of samples from open and from shaded sites revealed a higher capacity of thermal energy dissipation and an increase in the total amount of xanthophyll-cycle pigments (21%) in samples from open sites. In April, down-regulation of the efficiency of open photosystem II was related to lower water temperature, and hence, increased excitation pressure. In April the pool size of xanthophyll-cycle pigments was increased by 21% in comparison with summer and suggested higher levels of thermal energy dissipation via de-epoxidized xanthophylls. In both, summer and spring the amount of xanthophyll-cycle pigments was 20% higher in samples from open sites. Acclimation of C. glomerata to growth light conditions was further shown by experimental induction of NPQ, indicating NPQ increases of 23%, and increases of 77% in the reversible component of NPQ in open site samples. The effect of temperature on photosynthetic rate was non-linear, and different optimum temperatures of electron transport rate and oxygen evolution were exhibited. [source] The nutritional and metabolic indices in rats fed cholesterol-containing diets supplemented with durian at different stages of ripeningBIOFACTORS, Issue 2-3 2007Maria Leontowicz Abstract The aim of this investigation was to assess the nutritional and health properties of Mon Thong durian cultivar at different stages of ripening. The assessment was carried out in vitro and in vivo. The contents of dietary fibers, minerals and trace metals at different stages of ripening were comparable. Total polyphenols (mgGAE/100 g FW) and flavonoids (mg CE/100 gFW) in ripe durian (358.8 ± 31.4 and 95.4 ± 9.3) were significantly higher (p < 0.05) than in mature (216.1 ± 1 and 39.9 ± 3.8) and overripe (283.3 ± 26.2 and 53.5 ± 4.9). Antioxidant capacity (,MTE/100 g FW) in total polyphenol extracts of ripe durian measured by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and [2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) assays (259.4 ± 23.6 and 2341.8 ± 93.2) were significantly higher (p < 0.05) than that of mature (151.6 ± 15.2 and 1394.6 ± 41.5) and overripe (201.7 ± 19.4 and 1812.2 ± 61.4) samples. The correlation coefficients between the bioactive compounds in different stages of ripening and their antioxidant capacities were high (R2 = 0.99). Then 35 male Wistar rats were divided into 5 dietary groups each of 7 and named Control, Chol, Chol/Mature, Chol/Ripe and Chol/Overripe. During 30 days of the experiment the rats of all 5 groups were fed basal diet (BD), which included wheat starch, casein, soybean oil, vitamin and mineral mixtures. The rats of the Control group were fed a BD only. To the BD of the Chol group was added 1% of cholesterol. The BD of the Chol/Mature, Chol/Ripe and Chol/Overripe groups was supplemented with 1% of cholesterol and 5% of the mature, ripe and overripe durian as freeze-dried powder, respectively. Diets containing ripe and to a lesser degree mature and overripe durian significantly hindered the rise in plasma lipids and also hindered a decrease in plasma antioxidant activity. The nitrogen retention in rats of the Chol/Ripe group was significantly higher (63.6%, P < 0.05) than in other diet groups and the level of the plasma glucose remained normal. A decrease in fibrinogen fraction with ripe durian included in rat's diets was shown by electrophoretic separation. These changes were detected mostly in the low molecular weight proteins of rat's serum. Histological examination of aorta showed only slight differences in the tissue. In conclusion, ripe durian contains higher quantity of bioactive compounds, has higher antioxidant capacity and nutritional value. It positively affects the plasma lipid profile, the plasma glucose and the antioxidant activity in rats fed cholesterol enriched diets. Therefore, the ripe durian supplemented diet could be beneficial for patient suffering from hypercholesterolemia and diabetes mellitus. [source] | |||||||||||||