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171.
Natrophosphate is a common trace mineral in alkaline rocks and a major salt in alkaline nuclear waste that complicates waste processing. Natrophosphate has historically been assigned the composition Na7F(PO4)2·19H2O, but this conflicts with a more recent solubility study that claimed natrophosphate is a solid solution of NaF and Na3PO4. It is not possible to model the solubility of natrophosphate in nuclear waste until this controversy is resolved. The present study mixed stock solutions of 0.9 M NaF and Na3PO4 at different ratios at 8 °C. The compositions of the liquid phase and wet natrophosphate sample were measured by ion chromatography. Plotting the tie-lines between the solid and liquid phase composition showed convergence on a single composition, indicating that natrophosphate is not a solid solution. The resulting composition is approximately the same as the composition first reported more than 140 years ago. Thus, this study resolves the long-standing controversy in the literature concerning the composition of natrophosphate. 相似文献
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173.
The functioning of a honeybee colony relies on the coordination of colony activities via inter-individual interactions. While
the structure of this interaction network keeps the young individuals relatively isolated from the rest of the colony, there
are two possible mechanisms that can generate this organizational immunity. A spatial segregation that restricts the young
bees to the center of the colony can shield them with equal effectiveness as a behavioral segregation in which old bees choose
to interact with young bees less frequently. We test the role of these two mechanisms by determining the interaction frequency
between different age groups and testing their correlation with the olfactory sensitivity of different age groups to the cuticular
odor of each other. Young bees were found to interact with bees of all age groups with equal frequency, which correlates with
their lack of olfactory bias for any specific age, while old bees interacted more with other old bees, which correlates with
their higher olfactory sensitivity toward the cuticular odor of old bees. The distribution of olfactory responsiveness was
found to be positively skewed for old bees, which provides a mechanistic basis for the heterogeneous connectivity of the interaction
network observed in an earlier study. As old bees are more likely to be responsible for introducing a potential disease into
the colony from the outside and spreading it via the interaction network, these results suggest that behavioral segregation,
mediated by olfactory discrimination, plays an important role in generating the organizational immunity within the honeybee
colony. 相似文献
174.
Ammini Parvathi Seetha Radhakrishnan M. P. Sajila Breezy Jacob 《Environmental monitoring and assessment》2011,177(1-4):227-231
Accurate measurement of bacterial and viral abundance in coastal marine environments is important to understand the dynamics of microbial communities in these ecosystems. In this study, the effect of formaldehyde preservation on the abundance of bacteria and viruses in water samples from Cochin Backwater was determined by SYBR Green I staining and epifluorescence microscopy. The counts were determined for 45 days in samples fixed with 1?C6% formaldehyde. The results suggest rapid decline in counts of bacteria and viruses in samples preserved in formaldehyde, and the decline increased with increase in the final concentration of formaldehyde in the sample. The initial bacterial and viral counts in the sampling site were 5.2 × 106/ml and 3.9 × 107/ml, respectively. The bacterial count dropped by 5.1%, 53.3%, 55.7%, and 85% after 1, 7, 15, and 45 days, respectively, in sample fixed with 1% formaldehyde. The decline in viral counts was higher, being 32.4%, 47.9%, 68.1%, and 93% after 1, 7, 15, and 45 days, respectively. Storage of fixed samples at ??20°C did not halt the decline in microbial counts, suggesting that, irrespective of storage temperature, formaldehyde-fixed samples lead to underestimation of microbial counts. 相似文献
175.
Leif G. Salford Henrietta Nittby Arne Brun Gustav Grafström Jacob L. Eberhardt Lars Malmgren Bertil R. R. Persson 《The Environmentalist》2007,27(4):493-500
The environment in which biology exists has dramatically changed during the last decades. Life was formed during billions of years, exposed to, and shaped by the original physical forces such as gravitation, cosmic irradiation and the terrestrial magnetism. The existing organisms are created to function in harmony with these forces. However, in the late 19th century mankind introduced the use of electricity and during the very last decades, microwaves of the modern communication society spread around the world. Today one third of the world’s population is owner of the microwave-producing mobile phones. The question is: to what extent are living organisms affected by these ubiquitous radio frequency fields? Since 1988 our group has studied the effects upon the mammalian blood-brain barrier (BBB) by non-thermal radio frequency electromagnetic fields (RF-EMF). These have been revealed to cause significantly increased leakage of albumin through the BBB of exposed rats as compared to non-exposed animals—in a total series of about two thousand animals. One remarkable observation is the fact that the lowest energy levels give rise to the most pronounced albumin leakage. If mobile communication, even at extremely low energy levels, causes the users’ own albumin to leak out through the BBB, also other unwanted and toxic molecules in the blood, may leak into the brain tissue and concentrate in and damage the neurons and glial cells of the brain. In later studies we have shown that a 2-h exposure to GSM 915 MHz at non-thermal levels, gives rise to significant neuronal damage, seen 28 and 50 days after the exposure. In our continued research, the non-thermal effects (histology, memory functions) of long-term exposure for 13 months are studied as well as the effects of short term GSM 1,800 MHz upon gene expression. Most of our findings support that living organisms are affected by the non-thermal radio frequency fields. Studies from other laboratories in some cases find effects, while in other cases effects are not seen. Our conclusion is that all researchers involved in this field have the obligation to intensify this research in order to reduce, or avoid, the possible negative effects of the man made microwaves! 相似文献
176.
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178.
Staffan Jacob Léa Colmas Nathalie Parthuisot Philipp Heeb 《Die Naturwissenschaften》2014,101(11):929-938
Parasites are known to exert selective pressures on host life history traits since the energy and nutrients needed to mount an immune response are no longer available to invest in other functions. Bird feathers harbour numerous microorganisms, some of which are able to degrade feather keratin (keratinolytic microorganisms) and affect feather integrity and colouration in vitro. Although named “feather-degrading” microorganisms, experimental evidence for their effects on feathers of free-living birds is still lacking. Here, we tested whether (i) keratinolytic microorganisms can degrade feathers in vivo and thus modify the colour of feathers during the nesting period and (ii) whether feather microorganisms have a long-term effect on the investment in colouration of newly moulted feathers. We designed treatments to either favour or inhibit bacterial growth, thus experimentally modifying plumage bacterial communities, in a wild breeding population of great tits (Parus major). Our analyses revealed no significant effects of the treatments on feather colours. Moreover, we found that differences in bacterial exposure during nesting did not significantly affect the colouration of newly moulted feathers. Our results suggest that significant feather degradation obtained during in vitro studies could have led to an overestimation of the potential of keratinolytic microorganisms to shape feather colouration in free-living birds. 相似文献
179.
Getting to the First Handshake: Enhancing Security by Initiating Cooperation in Transboundary River Basins 下载免费PDF全文
Jacob D. Petersen‐Perlman Aaron T. Wolf 《Journal of the American Water Resources Association》2015,51(6):1688-1707
How does transboundary water cooperation begin at the initial stages, and how can third parties help to foster said cooperation? Many nations with transboundary waters do not cooperate or have ceased cooperation. Yet cooperation often prevails, resulting in 688 water‐related treaties signed from 1820 to 2007. We address the following: by which practices can development partners best design and implement cooperative projects at the state level to enhance basin water security in the earliest stages? This article identifies strategies for initiating cooperation and lessons drawn from reviewing select cases. We compiled from the Oregon State University Transboundary Freshwater Dispute Database all transboundary water resources projects over the last decade with multinational participation. We selected 10 case studies that enhance water security that fit the following filtering criteria: (1) Funding exclusively/primarily from outside sources, (2) Including nonofficial stakeholders in project design/implementation, (3) Absence of formal relations around water resources between or among the riparian nations before the project was discussed, (4) Project design possibly enhancing hydropolitical relations. Findings suggest that to enhance water security, project designs should respect participating riparians' autonomies, create basin‐wide networks of scientists, allow for each partner to garner responsibility for project activities, and consult a diverse group of stakeholders. 相似文献
180.
Perceived failure to reduce greenhouse gas emissions has prompted interest in avoiding the harms of climate change via geoengineering, that is, the intentional manipulation of Earth system processes. Perhaps the most promising geoengineering technique is stratospheric aerosol injection (SAI), which reflects incoming solar radiation, thereby lowering surface temperatures. This paper analyzes a scenario in which SAI brings great harm on its own. The scenario is based on the issue of SAI intermittency, in which aerosol injection is halted, sending temperatures rapidly back toward where they would have been without SAI. The rapid temperature increase could be quite damaging, which in turn creates a strong incentive to avoid intermittency. In the scenario, a catastrophic societal collapse eliminates society’s ability to continue SAI, despite the incentive. The collapse could be caused by a pandemic, nuclear war, or other global catastrophe. The ensuing intermittency hits a population that is already vulnerable from the initial collapse, making for a double catastrophe. While the outcomes of the double catastrophe are difficult to predict, plausible worst-case scenarios include human extinction. The decision to implement SAI is found to depend on whether global catastrophe is more likely from double catastrophe or from climate change alone. The SAI double catastrophe scenario also strengthens arguments for greenhouse gas emissions reductions and against SAI, as well as for building communities that could be self-sufficient during global catastrophes. Finally, the paper demonstrates the value of integrative, systems-based global catastrophic risk analysis. 相似文献