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11.
The regular associated solution model for binary systems has been modified by incorporating the size of the complex as an
explicit variable. The thermodynamic properties of the liquid alloy and the interactions between theA
μB type of complex and the unassociated atoms in anA-B binary have been evaluated as a function of relative size of the complex using the activity coefficients at infinite dilution
and activity data at one other composition in the binary. The computational procedure adopted for determining the concentration
of clusters and interaction energies in the associated liquid is similar to that proposed by Lele and Rao. The analysis has
been applied to the thermodynamic mixing functions of liquid Al-Ca alloys believed to contain Al2Ca associates. It is found that the size of the cluster significantly affects the interaction energies between the complex
and the unassociated atoms, while the equilibrium constant and enthalpy change for the association reaction exhibit only minor
variation, when the equations are fitted to experimental data. The interaction energy between unassociated free atoms remains
virtually unaltered as the size of the complex is varied between extreme values. Accurate data on free energy, enthalpy, and
volume of mixing at the same temperature on alloy systems with compound forming tendency would permit a rigorous test of the
proposed model. 相似文献
12.
Using information from our database, a review of mortality for the Newborn Intensive Care Unit at Providence Alaska Medical Center was conducted for 1987-1996. There has been a significant decline in mortality over the last decade (p = 0.003). An analysis of mortality by birthweight and gestational age groups demonstrated a decline in mortality (p = 0.005) for infants with birthweight < 2 kg and infants < or = 34 weeks gestation, but no change for infants > or = 2 kg and > or = 35 weeks gestation. As a result, larger and more mature babies now account for an increasing proportion of NICU deaths. For 1995 and 1996 the major contributors to mortality for the smaller neonates were respiratory distress syndrome and congenital and nosocomial sepsis/pneumonia. The major contributors to mortality for larger neonates were persistent pulmonary hypertension of the newborn, congenital heart disease, congenital diaphragmatic hernia, and primary birth asphyxia. A majority of deaths in the larger neonates were due to non-lethal causes. We contend that improved survival in the larger neonate is an important and achievable goal. The introduction of ECMO (Extracorporeal Membrane Oxygenation) for the NICU and a focused review of the neonatal cardiac program offers the best possible potential for achieving this goal. 相似文献
13.
Concentrations of benzo[a]pyrene and benzo[e]pyrene in the atmosphere as markers for the class of PAHs decreased by about 70% within one decade in clean air as well as in industrially polluted areas of Germany when measured with passive samplers (spruce sprouts, poplar and beech leaves). The same trend has been found for East-Germany during 1991-1995. Mussels (Mytilus edulis) were found to accumulate PAHs from the aquatic environment and exhibited a seasonal periodicity of the PAH concentration. After an initial decline from 1985 to 1990, the PAH concentration remained constant until 1995 in the North Sea area investigated. 相似文献
14.
T. F. Moura D. Gaudy M. Jacob A. Terol B. Pauvert A. Chauvet 《Drug development and industrial pharmacy》1996,22(5):393-400
Temperature variation in the spray drying method has no effect on the ascorbic acid molecule. No chemical interaction between the colloidal silica and the ascorbic acid could be determined, but a physicochemical interaction “absorption” was determined. Colloidal silica improved the final yield of spray drying in proportion to its concentration. No polymorphic forms could be determined in the spray-dried ascorbic acid. Drug release from the ascorbic acid spray dried was found to be dependent on the Aerosil content: highest release rates were obtained with Aerosil. 相似文献
15.
C Jurinke B Z?llner HH Feucht D van den Boom A Jacob S Polywka R Laufs H K?ster 《Canadian Metallurgical Quarterly》1998,14(3):97-102
DNA preparations from three different groups of serum samples were examined for HBV-DNA via a nested polymerase chain reaction assay (lower detection limit: 10 viral genomes in 100 microliters serum): Group I consisted of 11 uninfected control sera, group II consisted of sera obtained from 11 HBV infected patients and group III consisted of 21 isolated anti-HBc positive samples. The 21 samples from group III were HBV-DNA negative according to a conventional non-nested PCR assay and hybridization with a 32P-labelled probe. Using nested PCR and mass spectrometry, HBV-DNA was detected in none of group I and in all of group II samples. In 11 out of 21 (52%) of the isolated anti-HBc positive sera from group III, HBV-DNA was detected. No correlation was observed between HBV-DNA positivity and anti-HBc titers. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry provided a fast, sensitive and non-radioactive assay for the detection of PCR products without the need for gel electrophoresis or hybridization with labelled probes. 相似文献
16.
In this paper, a novel stochastic method is developed for despeckling transrectal ultrasound (TRUS) images of the prostate. By incorporating the circular probe acquisition particularities and speckle noise statistics of TRUS images of the prostate into a likelihood-weighted Monte Carlo estimation scheme, the proposed method can better remove speckle noise while preserving image structures and details that are relevant for image screening, allowing for a better delineation of the lesion contour. Our in silico and in vivo experimental results are promising, which was confirmed by a clinical evaluation of the in vivo test cases by experienced clinicians, and indicate that our method potentially can perform better than other previously proposed methods. 相似文献
17.
18.
Amanda Jacob 《Reinforced Plastics》2003,47(8):1
This issue contains a preview of the CFA’s annual trade show, which this year takes place in Anaheim, California. Those of you who also attend the JEC Composites Show in Paris will see a vast difference between these two events, not only in cultural terms but also in focus. CFA is an association for US manufacturers and its show places a high emphasis on education and networking. JEC’s slant is to the end-user and it strives to be a showcase for composites technology. Both of these approaches are to the ultimate benefit of the composites industry, but as companies continue to look at ways of spending their money more effectively, show attendance is one area coming under increasing scrutiny. Many have been saying that it is too expensive to attend JEC every year and now a group of major resin suppliers, including DSM, Reichhold, Ashland and Cray Valley, have taken the step of staying away from next year’s show (see page 64). This will surely dent the show’s profits and it will be interesting to see how the organisers, as well as other exhibitors, will respond to this development. 相似文献
19.
The aqueous eluate from fruits ofAmmi majus (Bishop's weed, Umbelliferae) remarkably inhibited germination of adjacent seeds ofAnastatica hierochuntica, lettuce, or tomato but had no effect on intact fruits ofAmmi. Similar inhibition was found in dark or in light, except that seeds ofA. hierochuntica were significantly more inhibited in the dark than in the light. Xanthotoxin was isolated, identified, and found to account for about a sixth of the inhibitory activity of the eluate. After fruits ofAmmi were submerged in a large volume of water for 4 days, the fruits still exuded enough inhibitors to prevent germination ofA. hierochuntica, lettuce, or tomato. Data support also the proposal that the phytotoxins are compartmentalized between the inner and the outer fruit envelopes. The inner layer excludes inhibitors from the embryo and autotoxicity is thus avoided, whereas the outer one ensures a gradual liberation of the phytotoxic compounds. This, as well as the high reactivity of the eluate, the high densities ofAmmi fruits in nature, and their relatively limited annual germination, suggest chemical inhibition of neighboring plant species other thanAmmi. Hence, in addition to their chemical protection against predators of either lower or higher organisms, furanocoumarins in fruits ofAmmi majus may contribute to its success as a weed. 相似文献
20.
The e.m.f. of a concentration cell for SO x (x=2,3)-O2 incorporating Nasicon as the main solid electrolyte has been measured in the temperature range 720 to 1080 K. The cell arrangement can be represented as, $$Pt, O'_2 + SO'_2 + SO'_3 \left| {Na_2 SO_4 \left\| {\left. {Nasicon} \right\|} \right.} \right.\left. {Na_2 SO_4 } \right|SO''_3 + SO''_2 + O''_2 , Pt$$ The Na2SO4 acts both as an auxiliary electrode, converting chemical potentials of SO x and O2 to equivalent sodium potentials, and as an electrolyte. The presence of Na2SO4 provides partial protection of Nasicon from chemical reaction with gas mixtures containing SO x . The open circuit e.m.f. of the cell is in close agreement with values given by the Nernst equation. For certain fixed inlet gas compositions of SO2+O2, the e.m.f. varies non-linearly with temperature. The intrinsic response time of the cell to step changes in gas composition is estimated to vary from ~2.0 ksec at 723K to ~ 0.2 ksec at 1077K. The cell functions well for large differences in partial pressures of SO3(p″SO 3/p′SO 3≈104) at the electrodes. 相似文献