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1.
Somatic embryo formation was induced from cotyledon explants of Styrian pumpkin (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) by using a solid MS medium supplemented with 16.11M NAA and 4.44M BA or 26.85M NAA and 13.32M BA. The callus proliferation was more efficient on medium supplemented with 26.85M NAA and 13.32M BA. In contrast, the embryogenic response was higher on medium with lower concentrations of growth regulators (16.11M NAA and 4.44M BA). The time needed for embryo induction did not depend on medium composition. Embryos in globular stage were transferred to three different maturation media, containing 2.89M GA3 in combination with 0.54M NAA, 11.42M IAA and growth regulator-free medium. The germination rate was the highest when embryos were cultured on medium with 11.42M IAA. Plantlets grown on this medium achieved maturity suitable for transplantation into soil within 9 to 10weeks. The regenerated plants were successfully transferred into field and developed fertile flowers and set fruits. Biochemical analysis showed significant lower total glutathione levels among in vitro grown plantlets compared to seedlings grown in soil. When the plantlets were transferred into soil, they reached a normal size within a month and the glutathione concentration was comparable to seed-derived plants at the same developmental stage. Transmission electron microscopy was used to investigate possible differences in the ultrastructure of cells from callus cultures, and leaf cells of regenerated and seed-derived plants. Differences in the ultrastructure were found within chloroplasts which contained only single thylakoids, large starch grains and small plastoglobuli in callus cells in comparison to leaf cells, which possessed a well developed thylakoid system, small starch grains and large plastoglobuli. 相似文献
2.
The Effects of Hypoxia on Three Sympatric Shark Species: Physiological and Behavioral Responses 总被引:1,自引:0,他引:1
Behavioral and physiological responses to hypoxia were examined in three sympatric species of sharks: bonnethead shark Sphyrna tiburo, blacknose shark, Carcharhinus acronotus, and Florida smoothhound shark, Mustelus norrisi, using closed system respirometry. Sharks were exposed to normoxic and three levels of hypoxic conditions. Under normoxic conditions (5.5–6.4mg l–1), shark routine swimming speed averaged 25.5 and 31.0cm s–1 for obligate ram-ventilating S. tiburo and C. acronotus respectively, and 25.0cm s–1 for buccal-ventilating M. norrisi. Routine oxygen consumption averaged about 234.6 mg O2kg–1h–1 for S. tiburo, 437.2mg O2kg–1h–1 for C. acronotus, and 161.4mg O2 kg–1 h–1 for M. norrisi. For ram-ventilating sharks, mouth gape averaged 1.0cm whereas M. norrisi gillbeats averaged 56.0 beats min–1. Swimming speeds, mouth gape, and oxygen consumption rate of S. tiburo and C. acronotus increased to a maximum of 37–39cm s–1, 2.5–3.0cm and 496 and 599mg O2 kg–1 h–1 under hypoxic conditions (2.5–3.4mg l–1), respectively. M. norrisi decreased swimming speeds to 16cm s–1 and oxygen consumption rate remained similar. Results support the hypothesis that obligate ram-ventilating sharks respond to hypoxia by increasing swimming speed and mouth gape while buccal-ventilating smoothhound sharks reduce activity. 相似文献
3.
S. M. Dawis 《Biological cybernetics》1978,30(4):187-193
An adaptation model having two stages is introduced and its mathematical properties are examined. The two stages are the adaptive process (parameter K
b), which has bleaching-type kinetics, and the response function (parameters K
r and n), which incorporates response saturation. In order to study the increment threshold functions generated by the adaptation model the concept of a detector is required. It is demonstrated that without an adaptive process the compression hypothesis, in the form of the difference equation, produces increment threshold functions which saturate and do not obey Weber's law. It is then shown that an adaptive process with bleaching-type kinetics can prevent saturation and produce Weber's law behavior provided that the adaptive strength of the system exceeds the detector sensitivity. 相似文献
4.
American ginseng, Panax quinquefolius L., is one of the most heavily traded medicinal plants in North America. The effect of harvest on genetic diversity in ginseng was measured with a single generation culling simulation program. Culling scenarios included random harvest at varying levels, legal limit random harvest and legal limit mature plant harvest. The legal limit was determined by the proportion of legally harvestable plants per population (% mature plants per population). Random harvest at varying levels resulted in significant loss of genetic diversity, especially allelic richness. Relative to initial levels, average within-population genetic diversity (H
e) was significantly lower when plants were culled randomly at the legal limit (Mann–Whitney U=430, p<0.001) or when only mature plants were culled (Mann–Whitney U=394, p<0.01). Within-population genetic diversity was significantly higher with legal limit mature plant harvest (H
e=0.068) than when plants were culled randomly at the legal limit (H
e=0.064; U=202, p<0.01). Based on these simulations of harvest over one generation, we recommend that harvesting fewer than the proportion of mature plants could reduce the negative genetic effects of harvest on ginseng populations. 相似文献
5.
A -amylase (EC 3.2.1.2) was identified in the outer pericarp (P) of developing seeds of wheat (Triticum aestivum L.) and compared with the well known -amylase which is synthesized during seed development in the starchy endosperm (E). The enzyme P already exists in the tissues before anthesis and vanishes at the time when E starts to accumulate. The isoelectric-focusing patterns of P and E are very similar. The relative molecular weight (Mr) of P is slightly higher than that of E (66 and 64.5 kDa, respectively). Both P and E exhibit common epitopes in addition to epitopes specific for each of them. The two enzymes were identified in small amounts in the green tissues of the developing seeds (inner pericarp and testa). No antigenic difference was detected between P and the -amylases of roots and leaves.Abbreviations
P
pericarp -amylase
-
E
endosperm -amylase
- IS1
anti--amylase immune serum
- IS2
anti- and anti- amylase immune serum
- IS3
anti- amylase immune serum
- IEF
isoelectric focusing
- IgG
immunoglobulin G
The authors thank Dr. P. Ziegler (Universität Bayreuth, FRG) for stimulating discussion and for useful suggestions during the writing of the text. The authors thank Miss C. Mayer for her skillful technical assistance. 相似文献
6.
Summary In this paper, the results of the preceding electrophysiological study of sodium-alanine cotransport in pancreatic acinar cells are compared with kinetic models. Two different types of transport mechanisms are considered. In the simultaneous mechanism the cotransporterC forms a ternary complexNCS with Na+ and the substrateS; coupled transport of Na+ andS involves a conformational transition between statesNCS andNCS with inward- and outward-facing binding sites. In the consecutive (or ping-pong) mechanism, formation of a ternary complex is not required; coupled transport occurs by an alternating sequence of association-dissociation steps and conformational transitions. It is shown that the experimentally observed alanine- and sodium-concentration dependence of transport rates is consistent with the predictions of the simultaneous model, but incompatible with the consecutive mechanism. Assuming that the association-dissociation reactions are not rate-limiting, a number of kinetic parameters of the simultaneous model can be estimated from the experimental results. The equilibrium dissociation constants of Na+ and alanine at the extracellular side are determined to beK
N
<-64mm andK
S
<-18mm. Furthermore, the ratioK
N
/K
N
S
of the dissociation constants of Na+ from the binary (NC) and the ternary complex (NCS) at the extracellular side is estimated to be <-6. This indicates that the binding sequence of Na+ andS to the transporter is not ordered. The current-voltage behavior of the transporter is analyzed in terms of charge translocations associated with the single-reaction steps. The observed voltage-dependence of the half-saturation concentration of sodium is consistent with the assumption that a Na+ ion that migrates from the extracellular medium to the binding site has to traverse part of the transmembrane voltage. 相似文献
7.
Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata 总被引:2,自引:0,他引:2
Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb1, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[-d-glucopyranosyl-(1,2)--d-glucopyranosyl]- 20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ene (1), 3-O-[-d-glucopyranosyl-(1,2)--d- glucopyranosyl]-20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ol (2), 3-O-[-d-gluco- pyranosyl-(1,2)--d-glucopyranosyl]-3, 12, 20(S)-trihydroxydammar-24-ene (3), and 3-O--d-glucopyranosyl-3, 12, 20(S)-trihydroxydammar-24-ene (4), identified by TOF-MS, 1H- and 13C-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound. 相似文献
8.
E. C. K. Pang G. M. Halloran 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,92(3-4):382-387
The genetic control of adult-plant blackleg (Leptosphaeria maculans) resistance in a Brassica napus line (579NO48-109-DG-1589), designated R13 possessing Brassica juncea-like resistance (JR), was elucidated by the analysis of segregation ratios in F2 and F3 populations from a cross between R13 and the highly blackleg-susceptible B. napus cultivar Tower. The F2 segregration ratios were bimodal, demonstrating that blackleg resistance in R13 was controlled by major genes. Analysis of the segregation ratios for 13 F3 families indicated that blackleg resistance in these families was controlled by three nuclear genes, which exhibited a complex interaction. Randomly sampled plants of F3 progeny all had the normal diploid somatic chromosome number for B. napus. The similarities between the action of the three genes found in this study with those controlling blackleg resistance in B. juncea is discussed. 相似文献
9.
Conversion of methanol to CH4 has a large isotope effect so that a small contribution of methanol-dependent CH4 production may decrease the 13CH4 of total CH4 production. Therefore, we investigated the role of methanol for CH4 production. Methanol was not detectable above 10 M in anoxic methanogenic rice field soil. Nevertheless, addition of 13C-labeled methanol (99% enriched) resulted in immediate accumulation of 13CH4. Addition of 0.1 M 13C-methanol resulted in increase of the 13CH4 from –47 to –6 within 2 h, followed by a slow decrease. Addition of 1 M 13C-methanol increased 13CH4 to +500 within 4 h, whereas 10 M increased 13CH4 to +2500 and continued to increase. These results indicate that the methanol concentrations in situ, which diluted the 13C-methanol added, were 0.1 M and that the turnover of methanol contributed only about 2% to total CH4 production at 0.1 M. However, contribution increased up to 5 and 17% when 1 and 10 M methanol were added, respectively. Anoxic rice soil that was incubated at different temperatures between 10 and 37 °C exhibited maximally 2–6% methanol-dependent methanogenesis about 1–2 h after addition of 1 M 13C-methanol. Only at 50 °C, contribution of methanol to CH4 production reached a maximum of 10%. After longer (7–10 h) incubation, however, contribution generally was only 2–4%. Methanol accumulated in the soil when CH4 production was inhibited by chloroform. However, the accumulated methanol accounted for only up to 0.7 and 1.2% of total CH4 production at 37 and 50 °C, respectively. Collectively, our results show that methanol-dependent methanogenesis was operating in anoxic rice field soil but contributed only marginally to total CH4 production and the isotope effect observed at both low and high temperature. 相似文献
10.
Structures of mitochondrial bc
1 complex have been reported based on four different crystalforms by three different groups. In these structures, the extrinsic domain of the Rieske [2Fe–2S]protein, surprisingly, appeared at three different positions: the c
1 position, where the [2Fe–2S]cluster exists in close proximity to the heme c
1; the b position, where the [2Fe–2S] clusterexist in close proximity to the cytochrome b; and the intermediate position where the[2Fe–2S] cluster exists in between c
1 and b positions. The conformational changes betweenthese three positions can be explained by a combination of two rotations; (1) a rotation of theentire extrinsic domain and (2) a relative rotation between the cluster-binding fold and thebase fold within the extrinsic domain. The hydroquinone oxidation and the electron bifurcationmechanism at the QP binding pocket of the bc
1 complex is well explained using theseconformational changes of the Rieske [2Fe–2S] protein. 相似文献
11.
The capacity of a soil to supply roots with water and nutrients for crop growth is important when defining sustainable land management which implies maintenance of production and reduction of production risks. Not only the amount of available water is important but also its accessibility, which differs among different soil structures. Different structures within one soil series were associated with three types of management: (i) conventional, temporary grassland (Conv), (ii) biodynamic, temporary grassland (Bio) and (iii) conventional permanent grassland (Perm). Transpiration of barley plants, under identical circumstances, and the associated rooting patterns, were measured in five large undisturbed cores from each of the three soil structures. Management had significantly changed bulk density, organic matter content and porosity. Measured transpiration showed significant differences with highest amounts for Perm followed by Conv and lowest amounts for Bio. Rooting pattern characteristics, defined as the relation between a series of hypothetical extraction zones around each root and the volumes of excluded soil were determined for the three structures. These rooting pattern characteristics were most favourable for Perm, followed by Bio and Conv, respectively. The water supply characteristics, defined as the number of days the soil can satisfy a transpiration demand of 5 mm d-1 as a function of a hypothetical extraction zone, reflects the capacity of the soil to supply roots with water. These water supply characteristics combined with the rooting pattern characteristics were used to quantify the accessibility of soil water. Accessibility was highest for Perm and Conv with 95% and 94% respectively, followed by Bio with 68%. When used in a simulation model and compared with simulations implicitly assuming total accessibility, measured transpirations were better simulated by introducing the expression for water accessibility. 相似文献
12.
Fumito Matsuura Masaya Ohta Khoichi Murakami Yujirou Matsuki 《Glycoconjugate journal》1993,10(3):202-213
Structures of the Asn linked oligosaccharides of quail egg-yolk immunoglobulin (IgY) were determined in this study. Asn linked oligosaccharides were cleaved from IgY by hydrazinolysis and labelled withp-aminobenzoic acid ethyl ester (ABEE) afterN-acetylation. The ABEE labelled oligosaccharides were then fractionated by a combination of Concanavalin A-agarose column chromatography and anion exchange, normal phase and reversed phase HPLC before their structures were determined by sequential exoglycosidase digestion, methylation analysis, HPLC, and 500 MHz1H-NMR spectroscopy. Quail IgY contained only neutral oligosaccharides of the following categories: the glucosylated oligomannose type (0.6%, Glc1-3Glc1-3Man9GlcNAc2; 35.6%, Glc1-3Man7–9GlcNAc2). oligomannose type (15.0%, with the structure Man5–9GlcNAc2) and biantennary complex type with core structures of-Man1-3(-Man1-6)Man1-4GlcNAc1-4GlcNAc (9.9%),-Man1-3(GlcNAc1-4)(-Man1-6)Man1-4GlcNAc1-4GlcNAc (25.1%) and-Man1-3(GlcNAc1-4)(-Man1-6)Man1-4GlcNAc1-4(Fuc1-6)GlcNAc (11.4%). Although never found in mammalian proteins, glucosylated oligosaccharides (Glc1Man7–9GlcNAc2) have been located previously in hen IgY.Abbreviations IgG, IgM, IgA, IgY
immunoglobulin G, M, A and Y, respectively
- ABEE
p-aminobenzoic acid ethyl ester 相似文献
13.
Rudolf Geyer Silvia Diabaté Hildegard Geyer Hans-Dieter Klenk Heiner Niemann Stephan Stirm 《Glycoconjugate journal》1987,4(1):17-32
Fowl plague virus, strain Dutch, was metabolically labeled withd-[2-3H]mannose, or withd-[6-3H]glucosamine, and the small subunit (HA2; 0.8 mg in total) of the viral hemagglutinin was isolated by preparative sodium dodecylsulfate-polyacrylamide gel electrophoresis. After proteolytic digestion, the radioactive oligosaccharides were sequentially liberated from the glycopeptides by treatment with different endo--N-acetylglucosaminidases and with peptide:N-glycosidase or, finally, by hydrazinolysis. In this manner, four groups of glycans could be obtained by consecutive gel filtrations and were subfractionated by HPLC. The structures of the individual oligosaccharides were analyzed by micromethylation, by acetolysis or by digestion with exoglycosidases. The major species amongst the high mannose glycans at Ans-406 of the viral glycopolypeptide were found to be Man1-2Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNac1-4GlcNAc and Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNAc1-4GlcNAc, while the complex glycans at Asn-478 are predominantly GlcNAc1-2Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc (lacking, in part, one of the outerN-acetylglucosamine residues) and GlcNAc1-2Man1-3(Gal1-4GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc.Abbreviation BSA
bovine serum albumin
- endo D (F,H)
endo--N-acetyl-d-glucosaminidase D (F,H)
- HA
hemagglutinin (HA1, large subunit of HA
- HA2
small subunit
- FPV
fowl plague virus
- PNGase F
peptide:N-glycosidase F
- SDS
sodium dodecylsulfate 相似文献
14.
The geometrical structures of phenylthiosemicarbazone (HAPhTSC) conformers have been obtained by geometry optimizations using density functional theory (DFT) calculations at the B3LYP/6-31G(d) and B3LYP/6-311G(d,p) levels of theory. Six thioamino and 24 thioimino tautomers of HAPhTSC have been found. Six tautomerization reactions between thioamino and thioimino tautomers occurring via transition states and their corresponding activation energies have been obtained. Conformational pathways for tautomerizations and interconversions of HAPhTSC conformers have been presented. Tautomerization between the most stable species of thioamino (Atttcc) and its thioimino (Itttcct) tautomer is an endothermic reaction, H0=18.17 kcal mol–1 and its log K=–13.74, at 298.15 K. Thermodynamic quantities of tautomerizations, interconversions of HAPhTSC conformers and their equilibrium constants are reported. The geometry of the zinc complex with HAPhTSC, found as a Zn(HAPhTSC)2Cl2 structure, has been obtained using B3LYP/6-31G(d) calculations. Binding of the Zn(HAPhTSC)2Cl2 complex is an exothermic and spontaneous reaction.Figure Conformational notation defined as a name consisting of a letter A for a thioamino tautomer followed by c for cis or t for trans isomerism of five dihedral angles of (C4-C3-C2-N3), (C3-C2-N3-N2), (C2-N3-N2-C1), (N3-N2-C1-N1) and (N2-C1-N1-H2), serially, or a letter I for b thioimino tautomer followed by c for cis or t for trans isomerism of six dihedral angles of (C4-C3-C2-N3), (C3-C2-N3-N2), (C2-N3-N2-C1), (N3-N2-C1-N1), (N2-C1-N1-H2) and (N2-C1-S-H1), serially.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
15.
Fumiaki Nakatsubo T. Kent Kirk Mikio Shimada Takayoshi Higuchi 《Archives of microbiology》1981,128(4):416-420
The degradation of the phenylcoumaran substructure model compound methyl dehydrodiconiferyl alcohol by the white-rot wood decay fungus Phanerochaete chrysosporium was investigated using culture conditions optimized for lignin oxidation. Initial attack was in the cinnamyl alcohol side chain, which was oxidized to a glycerol structure. This was subsequently converted by loss of the two terminal carbon atoms, C and C, to yield a C-aldehyde structure, which was further oxidized to the C-acid compound. The next detected intermediate, a phenylcoumarone, was produced by double bond formation between C and C, and oxidation of the C-alcohol to an aldehyde group. Further oxidation of C to an acid yielded the next intermediate. The final identified degradation product was veratric acid. No products from the 5-substituted aromatic ring, and no phenolic products, were found. The initial glycerol-containing intermediate was a mixture of the threo and erythro forms, and no optical activity could be found, suggesting that its formation might have involved nonstereospecific C-C epoxidation followed by non-enzymatic hydrolysis of the epoxide.Abbreviations TLC
thin layer chromatography
- LDA
lithium diisopropyl amide
- DDQ
2,3-dichloro-5,6-dicyanobenzoquinone
- MS
mass spectrometry
- UV
ultraviolet spectroscopy 相似文献
16.
Defining patch contribution in source-sink metapopulations: the importance of including dispersal and its relevance to marine systems 总被引:1,自引:1,他引:0
In metapopulations, individual patch contribution (source or sink) is typically calculated as a patch growth rate (the intrinsic lambda, I) dependent only upon local demographics. We demonstrate that when dispersal is explicitly included in the model, the growth rates for all patches calculated in an analogous manner (the observed lambda, O) equilibrate to the overall metapopulation growth rate and thus no longer serve as a useful reflection of the demographic and dispersive characteristics of a given patch. In these situations we suggest an alternative method of estimating patch contribution (the contribution lambda, C) in which a patch is decremented for losses that occur within it and credited for gains that occur anywhere in the metapopulation because of it. We compare values of I, O, and C for individual patches in discrete-time density-independent metapopulation models of two organisms with very different life histories, mayflies with adult dispersal, and reef fish with larval dispersal. Results confirm that when dispersal is included only C clearly indicates the contribution of a particular patch. I–C comparisons indicate that inclusion of dispersal in the mayfly model was only important if connectivity patterns were random or directional. In the reef fish model, however, results were very different when dispersal was included and there were many cases of patches being misidentified (e.g., as a source when it was really a sink) depending upon the metric used (I or C). Our results demonstrate the importance of including dispersal in metapopulation models when considering the contribution of individual patches. 相似文献
17.
Shafer FE Dropulic B Ely C Schaefer CA Freas D Witkowska HE Schechter AN Noguchi CT Dewey M Karlsson S 《Journal of biomedical science》1994,1(3):147-153
Two transgenic lines of mice were produced which contained the S
Antilles- and 2-hemoglobin genes trandemly coupled to the micro locus control region (LCR). The LCRS
Antilles2-hemoglobin transgenic mice expressed high levels of 2-hemoglobin while S
Antilles-hemoglobin expression was virtually undetectable. Abundant 2-hemoglobin protein was observed in the blood of transgenic mice, while S
Antilles-hemoglobin chains could not be detected. Transgenic red blood cells had substantially decreased sensitivity to osmotic lysis. Attempts to produce homozygotes containing the transgene were unsuccessful. The phenotype of these mice closely resembles that of -thalassemic mice. The LCRS
Antilles2 transgenic mice demonstrate that if the LCR is coupled to the S
Antilles- and 2-hemoglobin genes in tandem, only the distal 2-hemoglobin gene is selected for expression to significant levels in adult mice. These results support a reciprocally competitive model for LCR-hemoglobin developmental switching. 相似文献
18.
Narcolepsy has a 98% association with the DR2-Dw2/DQw1 haplotype. To establish if a disease-specific allele is present in narcolepsy, a cDNA library was made from a B-cell line from a DR2,4/DQw1,3 narcoleptic. Clones encoding the two expressed DR2
chains, along with DQw1 and chains, were isolated and completely sequenced. The coding regions of these four genes were similar to published nucleotide and protein sequences from corresponding healthy controls, with some minor exceptions. The 3 untranslated region of one of the DR2
genes in the narcoleptic was extended by 42 bp. Complete sequences were not available for DQw1.2 or from healthy individuals, but first domain nucleotide sequences showed only a single nonproductive difference in DQ. Partial protein sequences of both DQ and from published data were identical. Although the effects of minor differences cannot be ruled out completely, it is concluded that there are probably no narcolepsy-specific DR
or DQ / sequences, and that the alleles found in narcolepsy are representative of those found in the healthy population. 相似文献
19.
Hydrodynamic characteristics of two-phase inverse fluidized bed 总被引:1,自引:0,他引:1
Hydrodynamic characteristics of a new mode of liquid-solid fluidization, termed as inverse fluidization in which low density floating particles are fluidized with downward flow of liquid, are experimentally investigated. The experiments are carried out with low density particles (<534 kg/m3) which allow high liquid throughputs in the system. During the operation, three regimes, namely, packed, semi-fluidization and fully fluidization are encountered. Empirical correlations are proposed to predict the pressure drop in each regime. A computational procedure is developed to simulate the variation of pressure drop with liquid velocity.List of Symbols
Ar
modified Archimedes number, d
p
3
(–
s)g/2
-
d
p
particle diameter, mm
-
f
friction factor (eq. 2)
-
g
acceleration due to gravity, m/s2
- H
total bed height, m
-
H
c
height of the column, m
- Hf
height of fluidized bed, m
- H0
height of initial bed, m
- Hp
height of the packed bed, m
- (p)
pressure drop across the bed, N/m2
- (p)
f
pressure drop across fluidized bed section, N/m2
- (p)
p
pressure drop across the packed bed section, N/m2
- (p)
sf
total pressure drop in semifluidization regime, N/m2
- Re
Reynolds number, d
pU
1/
- Rem
modified Reynolds number, d
pU
1/(1–
p)
-
U
1
superficial liquid velocity, m/s
- Umf
minimum fluidization velocity, m/s
- Uosf
onset fluidization velocity, m/s
Greek Letters
f
voidage of fluidized bed
- p
voidage of packed bed
-
liquid viscosity, kg/ms
-
liquid density, kg/m3
-
s
particle density, kg/m3 相似文献
20.
Effie W. Petersdorf Robert L. Griffith Henry A. Erlich Eric M. Mickelson Anajane G. Smith Brenda B. Nisperos Paul J. Martin John A. Hansen 《Immunogenetics》1990,32(2):96-103
We have used restriction fragment length polymorphism (RFLP) analysis and DNA sequencing to characterize two distinct DRB1 alleles expressed on DRw52 and DQw7-associated haplotypes but not readily defined by conventional DR serology. These two haplotypes, designated HLA-D HAG and PEV, react variably with DRw13(w6), DRw14(w6), and the more broad DR 3+6 antisera. Analysis of RFLP revealed that HLA-D HAG and PEV are associated with different DRw52 variants, and that HAG is indistinguishable from DRw18(3) haplotypes. Sequencing of the HAG and PEV DRB1 genes showed each to represent novel alleles. Nevertheless, these sequences show similarities with the other alleles of the DR5, w6, and w8 family. HAG (DRB1*1303) appears to have arisen either from two recombinational events involving at least three DRB1 sequences (DRB1*1101, DRB1*0803, DRB1*0401) or from a single recombinational event together with multiple point mutational events. PEV appears to represent a DRB1*1301-1302/DRB1*1101 recombinant allele, with recombination having occured in the region of bases 175 – 198. The results of this study suggest that the DRw52 family haplotypes is derived from a relatively restricted number of ancestral sequences, with diversity among DRB1 alleles within this family arising through gene conversion or recombination events. 相似文献