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1.
A.S. Fraser 《Journal of Great Lakes research》1980,6(1):83-87
An apparent decrease in total phosphorus concentrations of approximately 4.l μgP/L has been reported recently for the spring values of 1977 and 1978 in Lake Ontario. Investigation of the loading reduction for this period independent of sedimentation factors can account for only 10% of the change. The results indicate that changes in the sedimentation rate of total phosphorus during this period offer an explanation for the majority of the change in concentration. 相似文献
2.
Summary The equilibrium water contents of linear poly(acrylic acid) sodium salts with different degrees of neutralisation were found to be dependent on temperature and relative humidity. An octahedral model for the primary hydration of poly(acrylic acid) sodium salts (HIRAOKA and YOKOYAMA 1980) was critically evaluated in the light of these findings and an anomaly in the water uptake versus neutralisation curve at approximately 33% neutralisation was explained by the counterion condensation theory. (MANNING 1979). 相似文献
3.
A new simultaneous synthesis approach for mass exchange networks (MENs) is presented. The technique is adapted from the interval based mixed integer non-linear program (MINLP) superstructure (IBMS) synthesis of heat exchanger networks (HENs). The superstructure interval boundary compositions are defined by the supply and target compositions of either the rich or lean set of streams. Each rich and lean stream in the superstructure has the potential of exchanging mass with streams of opposite kind in each interval based on mass transfer feasibility. The model harnesses the strengths of the stagewise superstructure and the pinch technology methods for mass exchange network synthesis (MENS). The IBMS approach simultaneously trades-off the capital and operating costs for MENs. The superstructure composition interval defining approach introduced in this paper enforces the mixing of split streams at equal compositions, hence there is no need to include mixing equations in the model. Fixing the interval boundaries helps to eliminate the complexities involved in initialisations, thus the region of search for the optimum solution is reduced. The IBMS model is applied to MENS problems involving continuous contact and staged columns. It is also extended to problems involving multiple mass separating agents (MSAs) and regeneration. The results obtained compare well with those in the literature. 相似文献
4.
Voltage switching induced by long-wavelength infrared light from a CO2 laser was observed using a double-barrier resonant tunneling diode (RTD) biased in the bistable region and the intersubband transition (IT) between the quantum confined states. Possible optoelectronic and all-optical switching applications involving hysteresis are proposed and discussed 相似文献
5.
6.
The fatty acid compositions of total polar and total neutral lipids of Atlantic herring eggs and larvae were determined immediately
before fertilization, after fertilization and at various times during subsequent embryonic and early larval development. Within
3 hr after fertilization the percentage of total PUFA in neutral lipid decreased from 33% to 20%, with a reciprocal increase
in monoenes. Thereafter the percentage of PUFA in the neutral lipids increased progressively, attaining the original level
in ripe eggs by the time of yolk sac absorption. During the larval stages the percentage of PUFA continued to increase in
the neutral lipid, reaching almost 44% of the total by day 32 after fertilization, although it was reduced to 32% by day 36.
The percentage of monoenes in the neutral lipid displayed a progressive decrease during the whole period of development from
3 hr after fertilization. Throughout all the developmental periods the fatty acid composition of total polar lipids remained
essentially constant. The polar lipids of the yolk sac displayed virtually the same fatty acid composition as the larval bodies,
but the neutral lipids of the yolk sac were low in PUFA compared to the larval bodies. The results are discussed with reference
to changes in lipid class composition during development. The conservation of high levels of PUFA in lipids during embryogenesis
and early larval development reflects the importance of these fatty acids during development. 相似文献
7.
GR Buchanan 《Canadian Metallurgical Quarterly》1993,23(6):219-29; discussion 218
8.
F. Kusmanto G. Walker Q. Gan P. Walsh F. Buchanan G. Dickson M. McCaigue C. Maggs M. Dring 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2008,139(2):398-407
The aims of this work were to investigate the conversion of a marine alga into hydroxyapatite (HA), and furthermore to design a composite bone tissue engineering scaffold comprising the synthesised HA within a porous bioresorbable polymer. The marine alga, Phymatolithon calcareum, which exhibits a calcium carbonate honeycomb structure, with a natural architecture of interconnecting permeable pores (microporosity 4–11 μm), provided the initial raw material for this study. The objective was to convert the alga into hydroxyapatite while maintaining its porous morphology using a sequential pyrolysis and chemical synthesis processes. Semi-quantitative XRD analysis of the post-hydrothermal material (pyrolised at 700–750 °C), indicated that the calcium phosphate (CaP) ceramic most likely consisted of a calcium carbonate macroporous lattice, with hydroxyapatite crystals on the surface of the macropores. Cell visibility (cytotoxicity) investigations of osteogenic cells were conducted on the CaP ceramic (i.e., the material post-hydrothermal analysis) which was found to be non-cytotoxic and displayed good biocompatibility when seeded with MG63 cells. Furthermore, a hot press scaffold fabrication technique was developed to produce a composite scaffold of CaP (derived from the marine alga) in a polycaprolactone (PCL) matrix. A salt leaching technique was further explored to introduce macroporosity to the structure (50–200 μm). Analysis indicated that the scaffold contained both micro/macroporosity and mechanical strength, considered necessary for bone tissue engineering applications. 相似文献
9.
This paper discusses how Britain's privatized energy market is working to ensure that there is enough gas and electricity to meet the demand. Since privatization, there has been around #30 billion invested in Britain's gas and electricity networks. This investment in unregulated infrastructure particularly demonstrates the response the market makes to deliver security of supply. Significant investment has also been made to build new plant when it is needed with the Renewables Obligation also leading to considerable investment in new renewable generation. There are also moves to address the upgrade and repair of networks that are more than 40 years old. 相似文献
10.
We have measured the proton-induced single-event upset (SEU) cross section of Xilinx XC4036XLA field programmable gate arrays. The threshold energy for SEU was determined to be (22/spl plusmn/2) MeV. The upset cross section saturated at a value of (2.7/spl plusmn/0.2)/spl times/10/sup -9/ cm/sup 2//device. We have demonstrated that Bendel models are unable to describe the upset cross section. The effects of the radiation environment of the liquid argon calorimeter of the ATLAS detector on the XC4036XLA were estimated. 相似文献