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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 36 (1997), S. 299-302 
    ISSN: 1436-6215
    Keywords: Energy retention ; protein retention ; fat retention ; growth ; body composition ; broilers ; Energieansatz ; Proteinansatz ; Fettansatz ; Wachstum ; Körperzusammensetzung ; Broiler
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Mit steigender Aufnahme erhöht sich der Körperfettgehalt und der Körperproteingehalt nimmt ab. Es wird oft angenommen, daß jede Zunahme im Ansatz mit mehr Fett und weniger Protein verbunden ist. Experimentelle Ergebnisse widerlegen jedoch diese Annahme. In zwei Experimenten mit männlichen Broilerhühnern wurden die Tiere auf einem Niveau von 60 % und 100 % der empfohlenen Energieaufnahme gefüttert. Die Körperzusammensetzung bei 1500 g zeigte, wie erwartet, daß sich bei steigenden Aufnahmen der Körperfettgchalt vergrößert und der Körperproteingehalt abnimmt. Fettund Proteinansatz waren linear mit der totalen Energieretention (ER) korreliert. Das bedeutet, daß jede Zunahme im Ansatz den gleichen Protein- und Fettgehalt besitzt. Wenn der Fettansatz gleich Null ist wird nur Protein, etwa 50 % des maximalen Ansatzes, retiniert. Wenn ER=O ist, wird Protein angesetzt und Fett mobilisiert. Energie-und N-Bilanzuntersuchungen bestätigen die konstante Zusammensetzung jeder Vergrößerung des Ansatzes. Die Ergebnisse beider Experimente zeigen, daß die ER aus zwei Komponenten besteht: einem basalen konstanten täglichen Proteinansatz und einer variablen zusätzlichen ER, die hauptsächlich aus Fett besteht. Der basale Proteinansatz beträgt etwa 50 % des maximalen Ansatzes. Mit steigenden Energieaufnahmen wird der basale Proteinansatz mit einer zusätzlichen Menge von Protein und Fett im konstanten Verhältnis ergänzt.
    Notes: Summary With increasing intakes the body fat content increases and that of protein decreases. It is most often assumed that this is brought about because each increment in retention contains more fat and less protein. Experimental results, however, showed that this explanation is not true. In two experiments male broiler chickens were fed at levels between 60 and 100 % of recommended energy intake. Body composition at 1500 g showed, as expected, that with increasing intakes body fat content increased and protein content decreased. Both fat and protein retention per day were linearly related to total energy retention (ER). This means that each increment in retention has the same protein and fat content. At zero fat retention only protein was retained, about 50 % of maximal retention. At zero ER protein was retained and fat mobilized. Energy and N balance experiments confirmed the constant composition of each increment in retention. The results of both experiments show that total ER consisted of two components: a basic constant daily protein retention and a variable additional ER, mainly consisting of fat. The basic protein retention is about half of maximal retention. With increasing energy intakes the basic protein retention is combined with an additional amount of protein and fat in a constant ratio.
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  • 2
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    European journal of nutrition 36 (1997), S. 332-335 
    ISSN: 1436-6215
    Keywords: Nutrient intake ; protein metabolism ; protein synthesis ; growth ; energy expenditures ; Nährstoffaufnahme ; Proteinstoffwechsel ; Proteinsynthese ; Wachstum ; Energieaufwand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Eine Zunahme von fettfreiem Gewebe tritt auf, wenn die Proteinsynthese größer ist als der Proteinabbau. Obwohl während des Wachstums von der Geburt bis zur Reife die absoluten Proteinsynthese- und -abbauraten ansteigen, nehmen dagegen die fraktionellen Raten ab. Bcide Prozesse reagieren auf die Nährstoffaufnahme. Es gibt aber deutliche Unterschiede zwischen den verschiedenen Geweben. Protein, Kohlenhydrate und Fett können den Proteinansatz bei unreifen Tieren und Kindern stimulieren. Die zugrundeliegenden Mechanismen und die Energieaufwendungen scheinen jedoch unterschiedlich zu sein.
    Notes: Summary Lean tissue growth occurs when the rate of protein synthesis exceeds the rate of protein breakdown. Althoughabsolute rates of protein synthesis and breakdown rise during growth from birth to maturityfractional rates fall. Both these processes are sensitive to nutrient intake but responses to feeding vary greatly amongst different tissues. Protein, carbohydrate and fat can all stimulate body protein accretion in immature animals and in children but the mechanisms by which they do so, and the energy expenditures involved, seem to be different.
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  • 3
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    European journal of nutrition 36 (1997), S. 205-213 
    ISSN: 1436-6215
    Keywords: Frying ; growth ; liver lipids ; lipaemia ; olive oil ; pregnancy ; rat ; Fritierung ; Wachstum ; Leberfett ; Olivenöl ; Schwangerschaft ; Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Um Informartionen über den Zusammenhang zwischen der Aufnahme von Fett, das zum Fritieren benutzt wurde, und dem Fetthaushalt während Perioden starken Körperaufbaus zu haben, wurde der Einfluß der Aufnahme von frischem Olivenöl (Gehalt polarer Verbindungen, 2 %; Ölsäure 78,9 mg/100 mg Öl, und Linolsäure 7 mg/100 mg Öl) und von Olivenöl, das 15 mal in Folge für das Fritieren von Kartoffeln benutzt worden war (Gehalt polarer Verbindungen 9 %; Ölsäure 75,8 mg/100mg Öl und Linolsäure 6,2 mg/100mg Öl) während der Gravidität, untersucht. Dazu wurden trächtige Wistar Ratten in zwei Gruppen geteilt, die beide eine isokalorische Diät bekamen, deren Fettanteil 15 % von frischem (unbenutztem) (P1) bzw. fritiertem (benutztem) (P2) Olivenöl stammte mit nicht trächtigen Ratten verglichen. Die Gravidität erhöhte (p〈0,01) die Futteraufnahme, das Körpergewicht, die Gewichtszunahmen und die Futterverwertung. Die Ölqualität beeinflußte dagegen diese Parameter nicht. Während der Gravidität stiegen die Serumwerte der Triglyceride (TG) (p〈0,01) und des Cholesterins (TC) (p〈0,05) an, während die der Phosphatide (PH) sanken (p〈0,01). Ein signifikanter Effekt der Ölqualität und eine Wechselwirkung zwischen Gravidität und Öl wurde für TG und PH festgestellt. Das Gewicht und der Fettgehalt der Leber der trächtigen Ratten stiegen signifikant an (p.〈0.05), Leber TC, TG und PH stiegen während der Gravidität (ungefähr um das 3-fache der Ausgangswerte), aber es traten keine signifikanten Unterschiede zwischen der Aufnahme von benutztem und nicht benutztem Öl (P2 vs P1) auf. Die Ergebnisse zeigen, daß die Aufnahme von leicht verdorbenem Olivenöl als alleinige Fettquelle der Nahrung keine besonderen Folgen für die Gravidität hat, was die Gewichtszunahme der Mütter und der Feten, die Lipämie und die Zusammensetzung des Leberfetts betrifft.
    Notes: Summary The effect of the consumption of unused olive oil (polar content, 2 %; oleic acid, 78.9 mg/100 mg oil, and linoleic acid 7 mg/100 mg oil) and olive oil used discontinuously for frying potatoes 15 times (polar content, 9 %; oleic acid, 75.8 mg/100 mg oil and linoleic acid 6.2 mg/100 mg oil) was studied in pregnant rats with the aim of better understanding the relationship between the consumption of fat used in frying and lipid metabolism during periods of intense anabolism. Trials were performed in pregnant Wistar rats, divided into 2 groups and fed isocaloric diets in which the fat content (15 % wt/wt) consisted of unused olive oil (P1) or oil previously used for frying (P2), and the results were compared with those of nonpregnant rats fed unused olive oil (NP1) and olive oil used for frying (NP2). Pregnancy increased (p〈0.01) food intake, body weight, weight gain, and food efficiency ratio (P2 vs NP2 and P1 vs NP1, respectively), but the treatment of oil included in the diets did not alter these parameters. Gestation significantly increased the serum triglyceride (TG) (p〈0.01) and total cholesterol (TC) (p〈0.05) concentrations and diminished that of phospholipids (PH) (p〈0.01). A significant effect of the type of oil consumed and a pregnancy x oil interaction on Tg and PH levels was observed. The weight of the liver and its fat content increased significantly (p〈0.05) as a result of pregnancy. Liver TC, TG, and PH increased (approximately 3 times the original values) during gestation, but no significant differences due to the intake of used or unused oil (P2 vs P1) were observed. The results indicate that the consumption of moderately altered olive oil, as the sole source of fat, does not alter the effect of pregnancy on the mothers' weight gain, lipaemia, and hepatic fat composition to any important degree.
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  • 4
    ISSN: 1436-6215
    Keywords: Body composition ; fat ; growth ; somatotropin ; pig ; Körperzusammensetzung ; Fett ; Wachstum ; Somatotropin -Schwein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung An 78 männlichen Kastraten und weiblichen Schweinen der Kreuzung Pietrain x (Deutsches Edelschwein x Deutsche Landrasse) wurden Untersuchungen zum Einfluß einer porcinen Somatotropin (pST)-Behandlung während des Wachstums auf die chemische Körperzusammensetzung der Tiere, das Adipozyten-Wachstum und das Fettsäure-Profil des Rückenspecks untersucht. Die intramuskulären Injektionen (1 oder 3 mg pST) wurden täglich ab durchschnittlich 65 kg Lebendgewicht bis zum Schlachten verabreicht. Nach der pST-Behandlung wurden bei den Kastraten in allen untersuchten Merkmalen signifikante Unterschiede festgestellt, während sich bei den weiblichen Tieren nur leichte Reaktionen zeigten. Das pST verursachte eine Zunahme des Wasserund Proteingehaltes bei gleichzeitiger Reduzierung des Lipidgehaltes besonders in den fettreichen Körperteilen der Tiere. Im Rückenspeck war der Gehalt an ungesättigten Fettsäuren erhöht und der Fettzelldurchmesser erniedrigt.
    Notes: Summary Seventy eight growing-finishing pigs (male castrates and females) of the cross-breed Pietrain x (Large White x German Landrace) were used to investigate the effects of pST treatment on the chemical composition of the body, the growth of adipocytes, and the fatty acid profile of the backfat. Intramuscular injections (1 or 3 mg pST) were administered daily from an average weight of 65 kg up to slaughter. After pST treatment significant changes in all studied characteristics were observed in barrows, whereas the females exhibited very small responses. The pST caused an increase of water and protein contents and a simultaneous decrease of lipid content especially in body parts rich in fat. Furthermore, the proportion of unsaturated fatty acids increased and the fat cell diameter decreased in the backfat.
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  • 5
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    Journal of productivity analysis 8 (1997), S. 293-310 
    ISSN: 1573-0441
    Keywords: growth ; USagriculture ; externalities ; spill-overs ; public R and D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Growth in U.S. agriculture is linked to the non-farm economy through domestic terms of trade and factor market adjustments. With almost stable input growth, the relatively large contributions from growth in Total Factor Productivity (TFP) are passed on to intermediate and final consumers in the form of declining real prices for primary farm products. The resulting net growth in the real value of farm output (GDP) is relatively low (0.25% per annum). The decomposition of TFP suggests that public agricultural stock of knowledge and infrastructure are “robustly” associated with TFP growth, while spill-overs from private agricultural and economy wide research and development (R and D) are positive but, relatively small.
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  • 6
    ISSN: 1432-1939
    Keywords: Key words Agrostis canina ; CO2 vents ; photosynthesis ; lignification ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The aim of this study was to characterise growth and photosynthetic capacity in plants adapted to long-term contrasting atmospheric CO2 concentrations (C a). Seeds of Agrostis canina L. ssp. monteluccii were collected from a natural CO2 transect in central-western Italy and plants grown in controlled environment chambers at both ambient and elevated CO2 (350 and 700 μmol mol−1) in nutrient-rich soil. Seasonal mean C a at the source of the plant material ranged from 610 to 451 μmol CO2 mol−1, derived from C4 leaf stable carbon isotope discrimination (δ13C). Under chamber conditions, CO2 enrichment stimulated the growth of all populations. However, plants originating from elevated C a exhibited higher initial relative growth rates (RGRs) irrespective of chamber CO2 concentrations and a positive relationship was found between RGR and C a at the seed source. Seed weight was positively correlated with C a, but differences in seed weight were found to explain no more than 34% of the variation in RGRs at elevated CO2. Longer-term experiments (over 98 days) on two populations originating from the extremes of the transect (451 and 610 μmol CO2 mol−1) indicated that differences in growth between populations were maintained when plants were grown at both 350 and 700 μmol CO2 mol−1. Analysis of leaf material revealed an increase in the cell wall fraction (CWF) in plants grown at elevated CO2, with plants originating from high C a exhibiting constitutively lower levels but a variable response in terms of the degree of lignification. In vivo gas exchange measurements revealed no significant differences in light and CO2 saturated rates of photosynthesis and carboxylation efficiency between populations or with CO2 treatment. Moreover, SDS-PAGE/ LISA quantification of leaf ribulose bisphosphate carboxylase/oxygenase (Rubisco) showed no difference in Rubisco content between populations or CO2 treatments. These findings suggest that long-term adaptation to growth at elevated CO2 may be associated with a potential for increased growth, but this does not appear to be linked with differences in the intrinsic capacity for photosynthesis.
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  • 7
    ISSN: 1573-4919
    Keywords: NADH oxidase ; plasma membranes ; growth ; retinol ; retinoids ; HeLa cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Several retinoids, both natural and synthetic, were evaluated for their ability to modulate NADH oxidase activity of plasma membranes of cultured HeLa cells and the growth of HeLa cells in culture. Both NADH oxidase activity and the growth of cells were inhibited by the naturally-occurring retinoids all trans-retinoic acid (tretinoin) and retinol as well as by the synthetic retinoids, trans-acitretin, 13-cis-acitretin, etretinate and arotonoid ethylester (Ro 13-6298). For all retinoids tested, inhibition of NADH oxidase activity and inhibition of growth were correlated closely. With tretinoin, etretinate and arotonoid ethylester, NADH oxidase activity and cell growth were inhibited in parallel in proportion to the logarithm of retinoid concentration over the range of concentrations 10-8 to 10-5 M. Approximately 70% inhibition of both NADH oxidase activity and growth was reached at 10 µM. With retinol, trans-acitretin and 13-cis-acitretin, inhibition of NADH oxidase activity and growth also were correlated but maximum inhibition of both was about 40% at 10 µM. The possibility is suggested that inhibition of the plasma membrane NADH oxidase activity by retinoids may be related to their mechanism of inhibition of growth of HeLa cells in culture. (Mol Cell Biochem 166: 101-109, 1997)
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  • 8
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    Journal of applied phycology 9 (1997), S. 19-24 
    ISSN: 1573-5176
    Keywords: Chaetoceros ; growth ; neutral lipid ; total lipid ; nitrogen deprivation ; Nile Red
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chaetoceros muelleri (Schütt) was cultured on a thermal gradient plate, subjected to two media types with a range of specific conductances, and evaluated for growth and neutral lipid accumulation. Growth was measured directly by daily changes in cell numbers and indirectly by changes in optical density at 750 nm. C. muelleri exhibited a growth rate of at least two doublings day-1 over broad temperature (20 to 35 °C) and conductance ranges (10 to over 60 mS cm-1) and the optimum growth rate approached 4.0 doublings day-1 at 30 °C and a conductance of 25 mS cm-1. Intracellular neutral lipid storage was evaluated with fluorometry and epifluorescent microscopy using the fluorochrome Nile Red. Gravimetric analysis revealed a total lipid content in nitrogen-depleted cultures of C. muelleri of over 400 mg L-1, five to seven times that observed in nitrogen-replete cultures. Based on its high growth rate, tolerance to a broad range of temperatures and specific conductances, and large quantity of intracellular lipid, C. muelleri may have potential for exploitation as a renewable precursor to liquid fuels or as a lipid source.
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  • 9
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    Journal of applied phycology 9 (1997), S. 437-444 
    ISSN: 1573-5176
    Keywords: Haematococcus pluvialis ; experimental design ; optimization ; culture medium ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A central composite rotatable design was used to examine the effects of five components of the medium on the growth of Haematococcus pluvialis in batch culture. The medium components considered were: sodium acetate,potassium nitrate, major elements, trace elements and vitamins. Within the range of the concentrations tested, a moderate concentration of the major elements significantly enhanced algal growth, both in terms of specific growth rate and cell dry weight, whereas the vitamins had no significant effect. Based on the response surface contour plots and the results of numerical analyses, the optimal nutrient concentrations for growth in terms of specific growth rate were 0.51 g L-1 sodium acetate, 0.25 g L-1 potassium nitrate, 0.63 mL L-1 of the major element stock solution and 0.2 mL L-1 of the trace element stock solution. The optimal nutrient concentrations for biomass production were 1.64 g L-1 sodium acetate, 0.37 g L-1potassium nitrate, 2.52 mL L-1 of the major element stock solution and 0.03 mL L-1 of the trace element stock solution.
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  • 10
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    Journal of applied phycology 9 (1997), S. 551-558 
    ISSN: 1573-5176
    Keywords: Spirulina ; Arthrospira ; growth ; salinity ; quantum yield ; nutrient status ; Chitu ; Ethiopia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spirulina platensis (=Arthrospira fusiformis) was isolated from Lake Chitu, a soda crater lake in the Ethiopian Rift Valley, where it formsa dense and almost unialgal population. Growth experiments were run in turbidostats under constant light, to assess growth response and tolerance to salinity, as well as to the component anions. Salinity was tested over the range 13–88 g L-1 using additions of NaHCO3, NaCl or Na2SO4. A maximum specific growth rate (µmax d-1) of 2.14 was achieved at the lowest salinity, but quantum yield (Φ%) was highest between 33 to 51 g L-1. Increasing salinity of the medium reduced the specific growth rate (µ) to a minimum of 0.33 d-1, and Φ to 〈 0.5%. Growth response in terms of µ and Φ was best in HCO 3 - , less in Cl-, and least in SO 4 2- series. Cultures showed obvious differences in cellular morphology, pigment, nitrogen and phosphorus contents in response to treatment with the different anions. Results indicate that the species has a wide range of tolerance to salinity from NaHCO3. Some degree of tolerance is also shown to high concentrations of Cl- and SO 4 2 , but with an overall lower performance of cells in terms of growth rate, light utilization efficiency, and nutrient status to cells grown in high HCO 3 - concentrations and the same levels of salinity and light.
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  • 11
    ISSN: 1573-5125
    Keywords: Marenzelleria ; Polychaetes ; macrozoobenthos ; abundance ; biomass ; population dynamics ; growth ; secondary production ; Baltic Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The propagation of an immigrant from North America, viz. the spionid Marenzelleria cf. viridis in the Darss-Zingst Bodden (DZB) (southern Baltic Sea), was studied at three stations from March 1992 to December 1995. Highest mean abundances (over 28 000 ind. m-2) and wet weights (400 g m-2) were recorded at station 2 in 1994. The spionid also reached its highest dominances in terms of biomass (40 to 90%) at this station, which was selected for the population dynamics, growth and secondary production studies. The spionid has a life span of about 3 years, and many individuals achieved sexual maturity after one year. Their growth curve is steepest during the first year of life, during which the animals grow to a length of about 180 segments. However, growth depression was observed during the ripening of the gametes in April, May and June. Secondary production was in the region of 55 to 85 g AFDW m-2 y-1. Productivity (P/B) varied considerably from generation to generation, ranging between 0 and 4.8 with an average between 1.2 and 1.6.
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  • 12
    ISSN: 1573-5125
    Keywords: Marenzelleria cf. viridis ; Polychaetes ; food limitation ; food selection ; growth ; gut passage time ; food quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytoplankton 〈 20 µm was a principal dietary component of the larvae of Marenzelleria cf. viridis. Maximum ingested particle size increased as animal size increased, reaching a maximum diameter of 80 µm for larvae with 6 to 10 setigers. The larvae started ingesting particulate matter at the 1-setiger stage and were able selectively to ingest phytoplankton and polystyrene particles of various sizes. Larvae in the 6 to 10-setiger size group did not differ from those in the 11 to 17-setiger size group in respect of size selectivity for polystyrene particles. The gut passage time for Chlorella vulgaris was ≥ 20 min. The ingestion rate was limited by food concentrations even at concentrations much higher than those encountered in the natural biotope, saturation being reached at a concentration of 28.5 times 106 cells ml-1 (117.7 mg C l-1. The low maximum filtration rate of only 1.19 µl ind.-1 h-1 indicates that the filtering capacity of the larvae is low. The larvae are still capable of food uptake at 1 °C. Further experiments demonstrated that larval growth and survival were strongly dependent on both food concentration and quality. Larval growth was food-limited under biotope conditions of the Darss–Zingst Boddens and even more so under Baltic Sea conditions. The results indicate that Marenzelleria cf. viridis is a species adapted to eutrophic conditions prevailing in brackish waters.
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  • 13
    ISSN: 1573-5176
    Keywords: Lyngbya wollei ; paralytic shellfish poisons ; growth ; toxin production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Collections of Lyngbya wollei were taken from Guntersville Reservoir, Alabama, over a period of three years. Healthy filaments were isolated and transferred to agar plates of Z-8 and LM6E media. Unialgal isolates were cultured for the study of growth and paralytic shellfish poison (PSP) production. Filaments were extracted and the toxins were detected using high performance liquid chromatography (HPLC) with post column oxidation followed by fluorescence detection. HPLC profiles show that laboratory cultures of L. wollei produced decarbamoyl gonyautoxin 2 and 3, plus several other PSP like toxins whose structures are under investigation. At 26 °C and a light intensity of 11 or 22 µmol m-2 s-1 optimum production of both biomass and toxins occurred. A decrease or increase in temperature or light flux caused a reduction in dry weight or toxicity. Compared to control levels, lower PO4-P and NO3-N and higher calcium levels gave rise to higher biomass and toxicity. Lower calcium, calcium- or PO4-P deficient medium and high NO3-N or PO4-P caused a large decrease in dry weight and toxicity.
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  • 14
    ISSN: 1573-1448
    Keywords: anaesthetic ; growth ; Haemulidae ; 2-phenoxyethanol ; Pomadasys commersonnii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 15
    ISSN: 1573-5117
    Keywords: microcrustacean zooplankton ; tropical limnology ; laboratory cultures ; growth ; development rates ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Length growth, instar durations, fecundity and mortality rates of fivespecies of microcrustacean zooplankton from a tropical reservoir weremeasured in relation to food quantity and temperature in laboratorycultures. Three cladocerans (Ceriodaphnia cornuta, Moina micrura,Diaphanosoma excisum), one calanoid copepod (Heliodiaptomus viduus), and onecyclopoid copepod (Mesocyclops thermocyclopoides) were studied. Filteredseston (45 µm mesh) from a local pond was used for food. Two foodconcentrations were employed: (1) 10 µg chlorophyll l−1(ca 0.25 mg Cl−1), and (2) 50 µg chlorophylll−1 (ca 1.25 mg C l−1). Food levels and watertemperature (22.5, 27.5, and 32.5 °C) used, roughly covered the rangesfound in the reservoir. Although all the three growth parameters were oftenaffected to some degree by temperature and food, the quantitative responseof the species differed. Also, the species reacted differently to the threepossible interactions (i.e. food × temperature,food × instar, andtemperature × instar). This contributed to the overalldifferences in the species responses. For the cladocerans, instar durationswere always affected by temperature. The food did not affect the durationtime of the adults and that of the combined juvenile instars, the latterexcept in one case significantly. For the two copepods food level affectedthe duration times of naupliar and copepodite instars, but the effect oftemperature was only significant for H. viduus. The development timesobserved for H. viduus were extraordinary long compared with values reportedin the literature for other tropical calanoids. This suggests that foodconditions in our culture were adversely affecting its growth rates.
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  • 16
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    Hydrobiologia 352 (1997), S. 287-293 
    ISSN: 1573-5117
    Keywords: Undaria pinnatifida ; translocation ; photoassimilates ; growth ; cultivation ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Undaria cultivation on a commercial scale began in China only in the last decade. Today, Undaria pinnatifida is the main species under cultivation concentrated in two provinces, Liaoning and Shandong. The annual production in the early nineties was 8000-13 000 tons dry weight, which is two or three times the pre-1980 figures. The raft cultivation method maintaining the alga at the desired depths generally ensures the light saturated rate of photosynthesis on clear days, and enhances production. Under the cultivated condition, the calculated annual primary productivity of this alga is 160 gC m−2 y−1. Translocation of 14C-labelled photoassimilates in rapidly growing sporophyte of Undaria pinnatifida was studied in the open sea. Samples from different parts of the blade with counterparts exposed to tracer (NaH14CO3) showed that the translocation that occurred mainly from the tip of the blade to the growing region had obvious source-sink relationship. It took 20 minutes to translocate the labelled photoassimilates from the epidermis, via cortex, to the medulla of the midrib, where rates of translocation averaging 42–48 cm h−1 were observed in the open sea. Production experiments of tip-cutting of the blades showed an increased production of 9%.
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  • 17
    ISSN: 1573-5117
    Keywords: stream ; disturbance ; caddisfly ; shredder ; diet ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diet and growth of leaf-shredding caddisfly larvae, Pycnopsyche spp.,were examined in streams draining a reference catchment and a 16-year-oldclear-cut (disturbed) catchment at Coweeta Hydrologic Laboratory insouthwestern North Carolina, USA. The objective was to explain why shredderproduction is higher in the disturbed streams despite the larvae having lessfood (i.e., leaves) available. We predicted larvae would grow faster onfast-decaying leaf material representative of the disturbed streams. Larvaeconsumed mostly leaf detritus in three streams draining each catchment overthree seasons (fall, winter, and spring), which showed larvae did notconsume higher quality foods (e.g., algae and animal material) in disturbedstreams. When fed 2-month-old conditioned black birch (Betula lenta L.) (afast-decaying leaf species) and white oak (Quercus alba L.) (a slow-decayingleaf species) leaves in the laboratory, larvae grew significantly faster onthe birch leaves. However, when larvae were fed the same leaf types after3-months conditioning, larvae grew significantly faster on oak leaves. Afield growth experiment conducted for 42 d using mixed-species leaf dietsrepresentative of each catchment and initially conditioned for 2 monthsfound that Pycnopsyche grew significantly better on the diet representativeof the reference catchment. The ’reference diet‘ contained more oak leaveswhich apparently became a more acceptable food as the experiment proceeded.High shredder production in the disturbed streams could not be explained byhigh Pycnopsyche growth rates on fast-decaying leaves. Instead, larvae grewbetter on leaves that were apparently conditioned optimally regardless ofconditioning rate.
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    ISSN: 1573-5117
    Keywords: grouper larvae ; live foods ; growth ; fatty acid
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    Topics: Biology
    Notes: Abstract Fertilized oyster eggs, S-rotifer (Brachionusrotundiformis) and SS-rotifer (Brachionus sp.),were tested either solely or in combination fortheir suitability as feed for early stage grouper (Epinephelus coioides) larvae. Sizes ofS-rotifers ranged between 143-224 µm lorica lengthwith mean 182±21µm, and SS-rotifersbetween 122-176µmlorica length with mean 154±13µm. Theresults indicated that both fertilized oyster eggs andSS-rotifers were suitable as feed at F1 (first feedingday). However, poor growth was recorded when providing oyster eggs solely for the periodsF1-F3. Although growth of larvae at F6 had nodifference between the sole SS-rotifers and the oystereggs additionally provided for F1-F3, better survivalof larvae at F15 was obtained when providingcombinations of SS-rotifers with oyster eggs for F1-F3.Besides, better growth and survival of larvae at F15was found when providing S-rotifers enriched withKirin yeast for F7-F15. The highest survival andfastest growth of larvae at F15 was found whenproviding oyster eggs for F1-F3, SS-rotifers forF1-F6, S-rotifers for F7-F15, both rotifers enrichedwith Kirin yeast, and Isochrysis for F1-F15.Total fatty acid (TFA), EPA, DHA content, and DHA/EPA(D/E) ratio of larvae changed with their sizes andcorresponded to that of their feeds. The F15 larvaehaving a higher TFA grew faster, having higher DHA orEPA survived better.
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    Plant molecular biology 35 (1997), S. 433-442 
    ISSN: 1573-5028
    Keywords: chickpea ; epicotyls ; growth ; tissue-specific gene expression
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    Topics: Biology
    Notes: Abstract Two cDNAs, CanST-1 and CanST-2, encoding two different growth-related organ-specific sequences have been isolated from a cDNA library from growing epicotyls of Cicer arietinum. An intriguing property of these two clones is the presence in their coding region of a repeated sequence which is highly conserved except for the number of repeats. The corresponding genes of CanST-1 and CanST-2 encode for proteins related to elongation processes. CanST-1 and CanST-2 are up-regulated during epicotyl growth, the transcript levels of both clones decrease when the growth of epicotyls is inhibited by several treatments and their expression increases when epicotyls resume growth. Furthermore, clones CanST-1 and CanST-2 are tissue-specific and are only expressed in epicotyls, mesocotyls, roots and stem tissues whose cells undergo elongation processes. Neither clone was found to be expressed in other organs such as cotyledons, leaves, flowers, pods and immature seeds. The results of auxin (IAA) and brassinolides (BR) treatments suggest that the processes in which the proteins encoded by CanST-1 and CanST-2 are involved are not mediated by these hormones.
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    International journal of primatology 18 (1997), S. 683-701 
    ISSN: 1573-8604
    Keywords: capuchins ; chimpanzees ; growth ; reproduction ; weaning
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    Topics: Biology
    Notes: Abstract We examined growth and development in capuchins and chimpanzees in relation to weaning, onset of reproduction, and reproductive life span. Striking differences are evident in neurobehavioral status at birth (more mature in capuchins), the relative duration of infancy (longer in chimpanzees), and the proportional weight of the infant at the time of weaning (greater in capuchins). Although capuchins and chimpanzees spend a similar proportion of life in a weaned but reproductively immature state, chimpanzees spend so much more of their lives as nursing infants that reproductive output per individual is much lower than in capuchins. Discussion centers around tolerated transfers of food (food-sharing) as a potential adaptation to limited foraging success by immature foragers. Perhaps food transfers from adult to infant, which is a more prominent feature of behavior in chimpanzees than in capuchins in natural environments, allow a very small weanling chimpanzee to survive.
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    Pharmaceutical research 14 (1997), S. 1122-1126 
    ISSN: 1573-904X
    Keywords: dissolution ; model ; growth ; fraction absorbed ; in vitro-in vivocorrelations
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop a new approach for describing drug dissolution which does not require the presuppositions of time continuity and Fick's law of diffusion and which can be applied to both homogeneous and heterogeneous media. Methods. The mass dissolved is considered to be a function of a discrete time index specifying successive 'generations' (n). The recurrence equation: Φ n+1 = Φ n + r(l − Φn)(1 − Φn X 0/θ) was derived for the fractions of dose dissolved Φ n and Φn +1, between generations n and n + 1, where r is a dimensionless proportionality constant, X 0 is the dose and θ is the amount of drug corresponding to the drug's solubility in the dissolution medium. Results. The equation has two steady state solutions, Φ ss = 1 when (X 0/θ) ≤ 1 and Φ ss = θ/X 0 when (X 0/θ) 〉 1 and the usual behavior encountered in dissolution studies, i.e, a monotonic exponential increase of Φ n reaching asymptotically the steady state when either r 〈 θ/X 0 〈 1 or r 〈 1 〈 θ/X 0. Good fits were obtained when the model equation was applied to danazol data after appropriate transformation of the time scale to 'generations'. The dissolution process is controlled by the two dimensionless parameters θ/X 0 and r, which were found to be analogous to the fundamental parameters dose anddissolution number, respectively. The model was also used for the prediction of fraction of dose absorbed for highly permeable drugs. Conclusions. The model does not rely on diffusion principles and therefore it can be applied under both homogeneous and non-homogeneous conditions. This feature will facilitate the correlation of in vitro dissolution data obtained under homogeneous conditions and in vivo observations adhering to the heterogeneous milieu of the GI tract.
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    Plant and soil 189 (1997), S. 33-48 
    ISSN: 1573-5036
    Keywords: development ; Elaeis guineensis ; growth ; oil palm ; root architecture ; root system
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The growth dynamics and architecture of the oil-palm root system are described. Following a transitional juvenile phase, eight different morphological types of roots have been distinguished according to their development pattern and state of differentiation: primary vertical and horizontal roots, secondary horizontal roots, upward growing secondary vertical roots and downward growing secondary vertical roots, superficial and deep tertiary roots and quaternary roots. The relative position of these types of roots determines a morphological and functional unit of the root system called 'root architectural unit' of the oil palm. This root polymorphism enabled us to define a morphogenetic gradient, which reflected the oil-palm root-system ontogenesis.
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    Plant and soil 189 (1997), S. 189-196 
    ISSN: 1573-5036
    Keywords: growth ; potassium deficiency ; potassium ; sodium ; tomato
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of potassium deficiency on hydroponically grown tomato were investigated at the early production stage (23 leaves, 3 trusses). Two types of potassium deficiency were applied : the permanent deficiency lasted for 23 days whereas the 10-day temporary deficiency was followed by a 7-day period of potassium supply resumption. Growth was assessed through non-destructive measurements. Permanent potassium deficiency resulted in growth slow-down before visual symptoms appeared on the adult leaves (leaves 12 to 17), but the older leaves (next to the first truss) were not affected. Temporary potassium deficiency reduced the growth rate, but, after potassium supply resumption, the plants recovered a growth pattern which was similar to that of the control plants. The potassium of the older leaves appeared to be less mobilizable than that present in the adult leaves where the visual deficiency symptoms appeared. Potassium uptake kinetics during the potassium supply resumption period were investigated on the plants submitted to temporary deficiency. In tomato plants which had been temporarily deprived of potassium before being transferred onto a standard nutrient solution, potassium uptake was faster than in the control plants. This result is to be related to the plant ability to recover a normal growth pattern. As a result of the occurrence of K-Mg and K-Na antagonisms, the sum of the cations was maintained at a constant value in some plant organs.
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    ISSN: 1573-5036
    Keywords: growth ; nodulation ; P supply ; symbiotic N2 fixation
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract P requirements of Casuarina cunninghamiana seedlings inoculated with Frankia and reliant on symbiotic N2 fixation were compared with those of uninoculated seedlings grown with 4 levels of fertilizer N in a solution culture system. Growth responses to increasing P supply depended on the N treatment that had been imposed. At the two lowest levels of N supply (0 μt M and 100 μt M) growth was relatively poor and there was no response to increasing P supply above 10 μt M and 50 μt M P respectively. In contrast, inoculated seedlings and those with higher levels of combined N (500 μt M and 1000 μt M) had significantly greater shoot dry weights (except at 0.1 μt M P), and they responded to increasing P supply to between 50 and 100 μt M P. At each level of P supply, the dry weights of seedlings in these 3 N treatments were similar. Nitrogen concentrations in shoots of seedlings provided with fertilizer N decreased with increasing P supply to 50 μt M and then remained unchanged. In contrast, N concentrations in shoots of inoculated seedlings increased with increasing P supply to 25 μt M P. At the 2 highest levels of P supply, N concentrations in shoots of inoculated plants were significantly higher than those in seedlings provided with fertilizer N. In all N treatments, P concentrations in shoots increased with increasing P supply; concentrations were similar in inoculated seedlings and those with the 2 highest levels of fertilizer N across all levels of P supply. Alleviation of P deficiency in inoculated seedlings increased nodule number, nodule dry weight, N2 fixation g-1 nodule dry weight (nodule 'efficiency'), P concentration in nodules, proportion of total seedling biomass allocated to nodules and average nodule size. However, all these parameters reached their maximum values at levels of P supply at, or below, those required for maximum host-plant growth (50 to 100 μt M P). The results indicate that the P requirement for host plant growth per se is similar to, or higher than, that required for symbiotic N2 fixation processes.
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    ISSN: 1573-5036
    Keywords: arbuscular mycorrhizal fungi ; growth ; nutrition ; preinoculated seedlings ; wetland rice ; yield
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We examined the effect of arbuscular mycorrhizal fungi inoculation at the nursery stage on the growth and nutrient acquisition of wetland rice (t Oryza sativa L.) under field and pot conditions. Seedlings were grown on γ-ray sterilized paddy soil in two types of nurseries, namely dry nursery and wet nursery, with or without arbuscular mycorrhizal fungi (AMF) inoculation which was a mixture of indigenous AMF (t Glomus spp.) spores collected from the paddy field. Five-to-six week old seedlings were transplanted to the unsterilized soil under field and pot, respectively. Mycorrhizal seedlings had higher shoot biomass under both nursery conditions 5 weeks after sowing. Mycorrhizal colonization and sporulation were 2 to 3 times higher in the dry nursery than the wet nursery at the transplanting stage. Mycorrhizal colonization of plants inoculated in the nursery remained higher than those not inoculated under both field and pot conditions. Sporulation after transplanting to field conditions was about 10 times higher than in the pot. Inoculated plants produced higher biomass at maturity under field conditions, and the grain yield was 14-21% higher than those not inoculated. Conversely, grain yield and shoot biomass were not significantly influenced by AMF colonization under pot conditions. For plants originating from the dry nursery, N, P, Zn and Cu concentrations of field-grown plants at harvest were significantly increased by preinoculation with AMF over those left uninoculated. We conclude that the AMF inoculation at the nursery stage under both dry and wet conditions increased growth, grain yield and nutrient acquisition of wetland rice under field conditions.
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    Plant growth regulation 21 (1997), S. 37-42 
    ISSN: 1573-5087
    Keywords: abscisic acid ; growth ; methyl jasmonate ; Oryza sativa
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of abscisic acid (ABA) and methyl jasmonate (MJ) on growth of rice seedlings were compared. The lowest tested concentration of ABA and MJ that inhibited seedling growth was found to be 4.5 and 0.9 µM, respectively. Growth inhibition by ABA is reversible, whereas that by MJ is irreversible. GA3 was found to be more effective in reversing inhibition of shoot growth by ABA than by MJ. KCl partially relieved MJ-inhibited, but not ABA-inhibited, growth of rice seedlings. The beneficial effect of K+ on growth of rice seedlings in MJ medium could not be replaced by Li+, Na+ or Cs+. MJ treatment caused a marked release of K+ into the medium. In order to understand whether cell wall-bound peroxidase activity was inversely related to rice seedling growth, effects of ABA and MJ on cell wall-bound peroxidase activity were also examined. Results indicated that both ABA and MJ increased cell wall-bound peroxidase activity in roots and shoots of rice seedlings. Although MJ (4.5 µM) was less effective in inhibiting root growth than ABA (9 µM), MJ was found to increase more cell wall-bound peroxidase activity in roots than ABA.
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    Environmental biology of fishes 49 (1997), S. 351-359 
    ISSN: 1573-5133
    Keywords: reproduction ; investment ; growth ; trade-off ; DNA ; RNA ; GSI ; LSI ; Barbus sclateri
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the nucleic acid levels of different tissues during a regular gonadal maturation were used to investigate the sex-related size differences in Iberian barbel, Barbus sclateri. Gonadal DNA concentration was associated with gonadal development in both sexes. There was a decline in DNA when ovaries were ripe. In contrast, the maximum size of the testes was related with highest gonadal DNA concentrations. Gonadal growth was not related with liver RNA : DNA ratios of male, while it was with female ratios. White muscle DNA concentrations indicate that somatic cell volume decreased during gonadal growth in both sexes. This suggests the translocation of several elements toward the gonad. Moreover, during gonadal maturation period adult barbel showed no change in their somatic growth. However, males apparently were in poorer metabolic condition (lower muscle RNA : DNA ratio) than females. Females may have allocated additional energy to self-maintenance rather than to breeding effort and it might influenced the cumulative annual growth. One might reasonably assume that there is a trade-off between investment in current versus future reproductive success in female. This result was not seen in males.
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    Environmental biology of fishes 50 (1997), S. 309-318 
    ISSN: 1573-5133
    Keywords: growth ; consumption ; metabolism ; body weight
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    Topics: Biology
    Notes: Abstract Food consumption, standard metabolism, and growth of juvenile snakehead, Channa striatus, a cannibalistic and air-breathing fish were measured at 24–26 °C under controlled laboratory condition. Snakehead weighing 3.2–29.5 g were evaluated, and were fed smaller snakehead. Based on our observations, we determined bioenergetics relationships between specific food consumption, metabolic rates, and body weight. These values, along with other published parameter values allowed us to construct a bioenergetics model for snakehead. We then verified our model with growth and food consumption measurements from an independent feeding trial. Predicted fish growth closely matched observed growth. Our model underestimated cumulative food consumption when a constant activity value was used, but consumption estimates improved when we used non-constant activity values (1-5 times of standard metabolism). Predicted fish maintenance ration was 1.7% of body weight per day. Food conversion efficiency was greatest (0.59) when fed 2% body weight daily, but declined when daily consumption exceeded 6% body weight. This model provides a useful approach for assessing food requirements of snakehead under controlled condition.
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    Environmental biology of fishes 48 (1997), S. 347-358 
    ISSN: 1573-5133
    Keywords: Acipenseridae ; Acipenser oxyrinchus ; Acipenser brevirostrum ; distribution ; habitat use ; movements ; size ; maturity ; age ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Hudson River estuary supports substantial number of Atlantic sturgeon, Acipenser oxyrinchus, and shortnose sturgeon, Acipenser brevirostrum. Both species have complex life cycles that have been studied sporadically in the past 50 years. The life cycle of the shortnose sturgeon may be divided into four life intervals: non-spawning adults, spawning adults, eggs and larvae, and juveniles. The life cycle of the Atlantic sturgeon is reviewed in six intervals: non-spawning adults, female spawners, male spawners, eggs and larvae, early juveniles, and late juveniles. Both species are long-lived, mature at advanced age, have rapid and similar growth during the first few years of life, feed on generally similar taxa, use deep channel habitats for all life intervals, and have complex migratory patterns with distinct, seasonal, concentration areas. Atlantic and shortnose sturgeons differ, however, in ages and sizes at maturity, maximum size, timing and location of spawning, migratory behaviors, and management. Use of marine habitats and long-distance coastal migrations are restricted to Atlantic sturgeon, but some evidence indicates that large Atlantic sturgeon juveniles reside in riverine habitats along the Atlantic coast during warm months. Movements and habitat use by both sturgeons in the Hudson River estuary contrasts with the spatial segregation of the species reported in other river systems. Juvenile shortnose sturgeon and early juvenile Atlantic sturgeon have almost the same distributions in the Hudson River estuary during all seasons. During this period of co-occurrence, both species are very similar in size, grow at about the same rate, feed on similar foods, and share deep, channel habitats. Adult shortnose sturgeon distribution overlaps with the distribution of juvenile Atlantic sturgeon, and the latter commence river emigration at a size comparable to co-occurring adult shortnose sturgeon. Life history information on the Hudson River sturgeons substantiates the need to carefully conserve these species because of vulnerability to exploitation and habitat disruption.
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    Plant cell, tissue and organ culture 49 (1997), S. 45-52 
    ISSN: 1573-5044
    Keywords: growth ; mannitol ; NaCl ; Nicotiana tabacum ; proline ; viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth, viability and proline content of adapted and unadapted calluses of Nicotiana tabacum L. var. Jayasri, affected due to osmotic stresses and particularly to stress-shocks treated with different osmotica like NaCl (ionic-penetrating), mannitol (non-ionic-penetrating) and polyethylene glycol, (PEG) (non-ionic-non penetrating) were studied to evaluate the physiological differences of stress effects. The tissues adapted to a low concentration of NaCl (85 mM) showed low growth with high proline content compared to the tissues adapted to a low concentration of mannitol (165 mM). Proline content was similar in tissues adapted to high concentrations of NaCl (171 mM) and mannitol (329 mM) but growth in the latter case was relatively low. Growth and viability were subsequently correlated with the pattern of retention in or diffusion of proline out of the tissues after shock-treatments. The loss of tissue viability of the adapted calluses was comparatively less than the unadapted callus even after shock-treatments with 1282 mM NaCl and 823 mM mannitol. The former calluses retained the capability of regrowth though at a slow rate. Such adapted tissues also retained more proline. The mannitol-adapted tissues, when shocked with PEG (200 g l-1), showed low viability with more diffusion and a very little retention of proline while, in the unadapted tissue, all the proline was leached out. The results indicated that the effects of different osmotica on plant tissue varied depending upon the physico-chemical nature of the compounds used as stress-inducing-agents, and retention and diffusion of proline was altered when the tissues were shocked with high concentrations of all these compounds.
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    Fish physiology and biochemistry 17 (1997), S. 231-236 
    ISSN: 1573-5168
    Keywords: growth ; salmon ; smoltification ; insulin ; insulin-like growth factor I (IGF-I) ; growth hormone ; thyroxine ; photoperiod ; temperature ; nutrition
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    Journal of economic growth 2 (1997), S. 155-168 
    ISSN: 1573-7020
    Keywords: growth ; taxation ; capital flight ; multiple equilibria ; redistribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This article shows that multiple growth paths may occurin a politico-economic model of endogenous growth. This multiplicityis characterized by the coexistence of the low-tax, low-capital-flightequilibrium and a high-tax, high-capital-flight equilibrium.The likelihood of multiplicity is crucially related to the structureof power in society—namely, it is necessary that the politicallydecisive agents have a greater access to international capitalmarkets than the average in the economy.
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    Journal of economic growth 2 (1997), S. 93-124 
    ISSN: 1573-7020
    Keywords: Income distribution ; human capital ; growth ; overlapping-generations ; Kuznets hypothesis
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    Topics: Economics
    Notes: Abstract This paper analyzes the interaction between the distributionof human capital, technological progress, and economic growth.It argues that the composition of human capital is an importantfactor in the determination of the pattern of economic development.The study demonstrates that the evolutionary pattern of the humancapital distribution, the income distribution, and economic growthare determined simultaneously by the interplay between a local home environment externality and a global technologicalexternality. In early stages of development the local home environmentexternality is the dominating factor and hence the distributionof income becomes polarized; whereas in mature stages of developmentthe global technological externality dominates and the distributionof income ultimately contracts. Polarization, in early stagesof development may be a necessary ingredient for future economicgrowth. An economy that prematurely implements a policy designedto enhance equality may be trapped at a low stage of development.An underdeveloped economy, which values equality as well as prosperity,may confront a trade-off between equality in the short-run followedby equality and stagnation in the long-run, and inequality inthe short-run followed by equality and prosperity in the longrun.
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    Journal of economic growth 2 (1997), S. 185-209 
    ISSN: 1573-7020
    Keywords: growth ; human capital ; development ; transition ; learning ; genetic algorithm
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    Topics: Economics
    Notes: Abstract This article develops the first model in which, consistentwith the empirical evidence, the transition from stagnation toeconomic growth is a very long endogenous process. The modelhas one steady state with a low and stagnant level of incomeper capita and another steady state with a high and growing levelof income per capita. Both of these steady states are locallystable under the perfect foresight assumption. We relax the perfectforesight assumption and introduce adaptive learning into thisenvironment. Learning acts as an equilibrium selection criterionand provides an interesting transition dynamic between steadystates. We find that for sufficiently low initial values of humancapital—values that would tend to characterize preindustrialeconomies—the system under learning spends a long periodof time (an epoch) in the neighborhood of the low-income steadystate before finally transitioning to a neighborhood of the high-incomesteady state. We argue that this type of transition dynamic providesa good characterization of the economic growth and developmentpatterns that have been observed across countries.
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    Journal of economic growth 2 (1997), S. 251-278 
    ISSN: 1573-7020
    Keywords: exploitation ; growth ; property rights ; taxation
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    Topics: Economics
    Notes: Abstract I develop a model of exploitation—coercive wealthtransfer—and growth based on social importance. Exploitationreduces growth since the return to capital falls with exploitationcosts. Initial relative wealth across groups—the measureof social importance—determines which group is the exploiterand how costly exploitation will be. The exploiter selects anexploitation path that maintains its dominant position and rarelymaximizes current transfers. Productive minorities and fast-growinggroups are most prone to exploitation. International sanctions,if strong, end exploitation; otherwise they increase exploitationand reduce growth. Segregation and apartheid are broadly consistentwith the theory.
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    Journal of economic growth 2 (1997), S. 305-329 
    ISSN: 1573-7020
    Keywords: growth ; income distribution ; tax and transfer policy ; human capital investment ; school effort
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    Topics: Economics
    Notes: Abstract The distortion in educational investment in poorer childrenis often attributed to credit market imperfections and henceto the unequal access of children to educational opportunity.However, the distortion might also be attributable to disincentiveeffects that cause children to make inefficient use of educationalopportunities. This possibility is demonstrated for an overlappinggenerations economy with multiple family dynasties in which childrenhave random unobservable abilities and base their school efforton their parents‘ after-tax returns to schooling. Income redistributioncan result in suboptimal effort choices that offset the beneficialeffects of income transfers and sharply lower social welfare.
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    Open economies review 8 (1997), S. 245-270 
    ISSN: 1573-708X
    Keywords: income distribution ; human capital ; growth ; complementarity
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    Topics: Economics
    Notes: Abstract This paper studies the role of income distribution and technology transfer in the process of economic development. A novel aspect of the model is that the composition of human capital as well as the level affect economic growth. Utilizing an overlapping-generations model in which income distribution changes endogenously, we present an economic explanation for why some countries could not start modern economic growth; why some countries took off but have apparently stopped growing after some time; and why some countries have successfully developed and continue to grow.
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    Review of industrial organization 12 (1997), S. 593-607 
    ISSN: 1573-7160
    Keywords: New information technology ; communication and business services ; innovation ; productivity ; growth
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    Topics: Economics
    Notes: Abstract This work analyses the outcome of the interaction between: 1) the diffusion of new information technologies; 2) their effects on the tradability, divisibility and transportability of information; 3) the growing role of business service industries in the introduction of new technologies; 4) the interaction between receptivity and connectivity of learning agents in the generation of localized technological change based upon both tacit and generic knowledge, and 5) the parallel increase in total factor productivity. The empirical results provide some support, with respect to the Italian economy, to two hypotheses: 1) The co-evolution of usage of business and communication services. Our empirical analysis has shown the strong correlation between the levels and rates of growth in the use of communication and business services. 2) The productivity enhancing effects of the co-evolution in the use of business and communication.
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    Journal of economic growth 2 (1997), S. 399-418 
    ISSN: 1573-7020
    Keywords: growth ; international spillovers ; spatial economics ; openness
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    Topics: Economics
    Notes: Abstract Does a country‘s long-term growth depend on what happensin countries that are nearby? Such linkages could occur for avariety of reasons, including demand and technology spillovers.We present a series of tests to determine the existence of suchrelationships and the forms that they might take. We find thata country‘s growth rate is closely related to that of nearbycountries and show that this correlation reflects more than theexistence of common shocks. Trade alone does not appear responsiblefor these linkages either. In addition, we find that being neara large market contributes to growth.
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    Journal of economic growth 2 (1997), S. 1-26 
    ISSN: 1573-7020
    Keywords: growth ; technology ; diffusion ; convergence ; adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract We construct a model that combines elements of endogenousgrowth with the convergence implications of the neoclassicalgrowth model. In the long run, the world growth rate is drivenby discoveries in the technologically leading economies. Followersconverge toward the leaders because copying is cheaper than innovationover some range. A tendency for copying costs to increase reducesfollowers‘ growth rates and thereby generates a pattern of conditionalconvergence. We discuss how countries are selected to be technologicalleaders, and we assess welfare implications. Poorly defined intellectualproperty rights imply that leaders have insufficient incentiveto invent and followers have excessive incentive to copy.
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    Journal of economic growth 2 (1997), S. 61-92 
    ISSN: 1573-7020
    Keywords: search ; matching ; mismatch ; human capital ; growth ; wage inequality ; income inequality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This paper analyzes a model in which firms and workershave to engage in costly search to find a production partner,and endogenizes the skill, job, and wage distributions in thiscontext. The presence of search frictions implies that thereare two redistributive forces in the labor market. The firstis mismatch relative to the Walrasian economy; skilled workerstend to work with lower physical to human capital ratios, andthis compresses the earnings differentials. The second is theopportunity cost effect; because the opportunity cost of acceptingan unskilled worker, which is to forgo the opportunity to employa skilled worker, is high, unskilled wages are pushed down. Theinteraction between these two forces leads to a non-ergodic equilibriumprocess for wage and income inequality. Further, the presenceof mismatch reduces the rate of return to physical capital andthus depresses growth. A key prediction of the analysis is thatincreasing wage inequality is more likely to arise in economieswith less frictional labor markets, which is in line with thediverse cross-country patterns observed over the past two decades.Finally, the paper predicts that, as is largely the case withU.S. data, between group and within group wage inequality shouldmove in the same direction.
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    Journal of economic growth 2 (1997), S. 169-183 
    ISSN: 1573-7020
    Keywords: growth ; democracy ; education ; inequality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract We use an OLG model to examine democratic choice betweentwo modes of government support for education: subsidies forprivately purchased education and free uniform public provision.We find little conflict between democracy and growth: the samefactors that generate popular support for subsidization overfree uniform provision—large external benefits, a largeexcess burden, and little inequality—also favor its relativegrowth performance. Furthermore, restricting the franchise toan upper-income elite may also reduce growth. Two extensionsexamine the effect of intergenerational mobility and indicatethe theoretical possibility of periodic swings in the balancebetween public and private spending.
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    Hydrobiologia 359 (1997), S. 191-197 
    ISSN: 1573-5117
    Keywords: Conchostraca ; branchiopod ; growth ; survival ; reproduction ; carapace rings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several life history measures (growth rate, egg production, molt frequency, age at maturity and lifespan) were measured on several clam shrimp hermaphrodites (Eulimnadia texana Packard) grown in a laboratory setting under optimal growth conditions. Growth rates were high early in life, and then dropped dramatically when egg production began (day 5–6). Early egg production was low, and increased until approximately day 7, after which production leveled off for several days. Reproductive senescence was noted after day 17, with clutch sizes continuously dropping until death. Average molts per day was approximately 1.1, and molting seemed to be more closely associated with egg production than with growth. Growth and egg production were negatively correlated, indicating a possible trade-off between these two traits. No other trade-offs were detected. These shrimp show typical early-colonist life history traits, displaying high initial growth, early reproduction at a high rate, and then early senescence and death.
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    World journal of microbiology and biotechnology 14 (1997), S. 113-118 
    ISSN: 1573-0972
    Keywords: Aspergillus ; continuous culture ; glucoamylase ; growth ; fungi ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Maltose-limited continuous culture of Aspergillus niger was carried out with potassium nitrate to investigate growth and glucoamylase formation characteristics. Glucoamylase production was dependent on the specific growth rate. The maximal amount of glucoamylase (units/l and U/g dry weight) was obtained at μ=0.08h−1, and the maximum specific rate of production (units/g/dry weight per hour) was at μ=0.2h−1. The maintenance coefficients (ms and mATP) were higher than for some other fungi. Maximal growth yields on substrate, oxygen and ATP (Yxsm, YxO2m and Yxam) were very efficient (high) and the value of Yxam, which cannot exceed the theoretical maximal value, is obtained when a P/O ratio of 1:1 is assumed. This indicates that biomass formation is energetically inexpensive and most of the expended energy has to be invested in the process of glucoamylase excretion.
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    Journal of chemical ecology 23 (1997), S. 543-551 
    ISSN: 1573-1561
    Keywords: Temperature ; photoperiod ; hydroxamic acids ; growth ; defense ; secondary metabolites ; wheat ; Gramineae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effects of temperature and photoperiod on accumulation of hydroxamic acids (Hx) in wheat (Triticum aestivum L.) seedlings were evaluated under laboratory conditions. Hx concentrations were significantly higher at higher temperatures. No such clear trend was found for the photoperiod effect. The significant effect of temperature and photoperiod on growth rate of seedlings and the significant positive correlation between growth rate prior to analysis and levels of Hx, suggested that environmental effects on Hx accumulation were at least partially mediated through their effect on plant growth rate. After uncoupling the effect of environmental conditions from the effect of plant growth rate by statistical means the effect of temperature on Hx was no longer significant. Therefore, temperature effect was fully mediated by plant growth rate. Implications of the patterns found are discussed in issues of plant-defense general theories.
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    Journal of statistical physics 87 (1997), S. 607-611 
    ISSN: 1572-9613
    Keywords: Scaling ; percolation ; growth ; intermittency ; moments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Havlin-Bunde multifractal hypothesis for the probability density of a random walker is used to obtain the scaling law of thepth-order correlation function of the concentration (for percolation) and of the height (for growing surfaces) differences:c p (r)=〈|Θ(x+r)−Θ(x)| p 〉∼r ς p in intermittent media. It is shown that near the transition to homogeneity σ p =A p In(p/p o)(whereA andp 0 are some constants). Good agreement with recent experiments and computer simulations of different authors is established.
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    Hydrobiologia 363 (1997), S. 13-27 
    ISSN: 1573-5117
    Keywords: Copepods ; growth ; mortality ; grazing ; vertical flux
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Copepods constitute the majority of the mesozooplankton in the oceans.By eating and being eaten copepods have implications for the flow of matterand energy in the pelagic environment. I first consider populationregulation mechanisms in copepods by briefly reviewing estimates of growthand mortality rates and evidence of predation and resource limitation. Theeffects of variations in fecundity and mortality rates for the demography ofcopepod populations are then examined by a simple model, which demonstratesthat population growth rates are much more sensitive to variations inmortality than to variations in fecundity. This is consistent with theobserved tremendous variation in copepod fecundity rates, relatively low andconstant mortality rates and with morphological and behavioralcharacteristics of pelagic copepods (e.g., predator perception and escapecapability, vertical migration), which can all be considered adaptations topredator avoidance. The prey populations of copepods, mainly protozoa(ciliates) and phytoplankton, may be influenced by copepod predation tovarying degrees. The highly variable morphology and the population dynamics(e.g., bloom formation) of the most important phytoplankton prey populations(diatoms, dinoflagellates) suggest that predation plays a secondary role incontrolling their dynamics; availability of light and nutrients as well ascoagulation and sedimentation appear generally to be more important. Thelimited morphological variation of planktonic ciliates, the well developedpredator perception and escape capability of some species, and the oftenresource-unlimited in situ growth rates of ciliates, on the other hand,suggest that copepod predation is important for the dynamics of theirpopulations. I finally examine the implications of mesozooplankton activityfor plankton food webs, particularly their role in retarding vertical fluxesand, thus, the loss of material from the euphotic zone.
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  • 48
    ISSN: 1573-5168
    Keywords: amago salmon ; GH ; growth ; GSI ; immature ; IGF-I ; mature ; radioimmunoassay ; smoltification ; thyroxine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seasonal changes in plasma levels of insulin-like growth factor I (IGF-I) in precociously maturing amago salmon (Oncorhynchus masou ishikawai), which matured as 1-year-olds, have been investigated. Profiles of plasma IGF-I levels were compared with changes in growth and maturity, and plasma growth hormone (GH) and thyroxine (T4) concentrations. The maturity of the fish was determined by calculating the gonadosomatic index; in November, 100% of males and 89% females matured. In both males and females, plasma IGF-I levels increased from March to August, and subsequently, plasma IGF-I levels in the early maturing males and females declined gradually and were maintained at lower levels during the spawning period in November. Plasma GH levels were high in April, and then declined gradually through September. Thereafter, in early maturing fish, a slight increase in plasma GH levels was observed in October and November. No significant changes in plasma T4 levels were found in the precociously maturing fish. In sharp contrast, plasma IGF-I levels in immature fish remained elevated through September, reaching a peak in October, and then gradually declined in November. In immature females, plasma T4 and GH levels were elevated in August, reached their maximum in September and then gradually declined until November.
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  • 49
    ISSN: 1573-2932
    Keywords: chlorophyll content ; gas exchange ; growth ; ozone ; redpine ; soil acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract One-year-old seedlings of red pine (Pinus densiflora Sieb. and Zucc.) were grown in typic red-yellow forest soil (Typic Hapludults) artificially adjusted to pH (H2O) 3.15, 3.60 or 3.90 by adding H2SO4 solution to the soil (pH 4.60), and exposed to ozone (O3) at 150±10 ppb (nl⋅L-1) for 8 h a day, 6 days a week, for 16 weeks from June 5 to October 5, 1994. The control seedlings were exposed to charcoal-filtered air (CF) and grown in the soil without the additional supply of H+ as H2SO4 solution during the same period. No significant interactive effects of O3 and soil acidification were observed for the determined seedling parameters in this study. However, O3 caused a reduction in needle dry weight, net photosynthetic rate and chlorophyll contents in the needle tip or on whole-needle weight basis, and stimulated rates of dark respiration and photorespiration. There were no significant effects of O3 on chlorophyll contents in the needle middle and basal parts, transpiration rate or water use efficiency (WUE). On the other hand, the seedlings grown in the soil adjusted to pH 3.60 or 3.90 showed a reduction in needle dry weight, net photosynthetic rate, chlorophyll contents in all the needle parts and WUE, and an increase in the rates of dark respiration and photorespiration. The transpiration rate of the seedlings was not significantly affected by soil acidification. All the seedlings grown in the soil adjusted to pH 3.15 died during the first 4 weeks. Soil and needle analysis suggested that high concentrations of Al and low Ca/Al ratios in the acidified soil were stressors.
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  • 50
    ISSN: 1573-2932
    Keywords: chlorophyll content ; gas exchange ; growth ; ozone ; red pine ; soil acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract One-year-old seedlings of red pine (Pinus densiflora Sieb. and Zucc.) were grown in typic red-yellow forest soil (Typic Hapludults) artificially adjusted to pH (H2O) 3.15, 3.60 or 3.90 by adding H2SO4 solution to the soil (pH 4.60), and exposed to ozone (03) at 150±10 ppb (nl·L−1) for 8 h a day, 6 days a week, for 16 weeks from June 5 to October 5, 1994. The control seedlings were exposed to charcoal-filtered air (CF) and grown in the soil without the additional supply of H+ as H2SO4 solution during the same period. No significant interactive effects of O3 and soil acidification were observed for the determined seedling parameters in this study. However, O3 caused a reduction in needle dry weight, net photosynthetic rate and chlorophyll contents in the needle tip or on whole-needle weight basis, and stimulated rates of dark respiration and photorespiration. There were no significant effects of O3 on chlorophyll contents in the needle middle and basal parts, transpiration rate or water use efficiency (WUE). On the other hand, the seedlings grown in the soil adjusted to pH 3.60 or 3.90 showed a reduction in needle dry weight, net photosynthetic rate, chlorophyll contents in all the needle parts and WUE, and an increase in the rates of dark respiration and photorespiration. The transpiration rate of the seedlings was not significantly affected by soil acidification. All the seedlings grown in the soil adjusted to pH 3.15 died during the first 4 weeks. Soil and needle analysis suggested that high concentrations of Al and low Ca/Al ratios in the acidified soil were stressors.
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    Photosynthetica 34 (1997), S. 293-302 
    ISSN: 1573-9058
    Keywords: amino acids ; 14C photoassimilation ; dark respiration rate ; growth ; Hordeum vulgare ; photoassimilates ; proteins ; transpiration rate ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Barley plants (Hordeum vulgare L. cv. Obzor) were grown as a water culture in a climatic room. One part of them was subjected to a long-term Cd2+ stress - 12 d with 5.4×10−5 M Cd. The Cd2+ stress inhibited formation of the photosynthetic apparatus and its capacity for 14C photoassimilation, decreased the content of soluble proteins, increased the dark respiration rate and the free amino acids content, disturbed plant water relations, as well as the distribution of 14C within primary photoproducts of the treated barley plants.
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    Photosynthetica 34 (1997), S. 321-342 
    ISSN: 1573-9058
    Keywords: genetic apparatus ; growth ; oxidative enzymes ; photosynthetic apparatus ; senescence ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Copper (Cu) is a heavy metal which in recent studies has been attributed an increasing role in metabolic processes of plant cells. It is an indispensable component of oxidative enzymes or of particular structural components of cells. At elevated concentrations, Cu can act strongly on chromatin, the photosynthetic apparatus, growth, and senescence processes. The mechanisms of the metal toxicity depending largely on the growth stage of treated plants are presented in this review.
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  • 53
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    Chemical Engineering & Technology - CET 20 (1997) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Chemical Engineering & Technology - CET 20 (1997), S. 17-22 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mass transfer with chemical reaction by liquid/liquid phase tranfer catalysis (LLPTC) for an isothermal batch reactor was analyzed. The results for the phase transfer catalyzed reaction system can be generally described by a pseudo first-order hypothesis, whereas the reaction system can be controlled by simultaneous mass transfer of the catalysts between two liquid phases and chemical reaction in the organic phase. The mass transfer limitation is mainly from the mass transfer step of QX from the organic phase to the aqueous phase. The concept of catalyst-effectiveness vs. physically meaningful parameters in a liquid/liquid phase transfer catalyzed reaction is introduced. The catalyst effectiveness is increased as the mass transfer factors increase, the ratio of reaction rate coefficients of aqueous forward reaction to organic increases, and the equilibrium constant in the aqueous solution increases.
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    Chemical Engineering & Technology - CET 20 (1997), S. 40-42 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of ozone and hydrogen peroxide for the simultaneous oxidation of nitrogen and sulfur oxides was studied in experiments carried out in a stirred cell. It was found that in a gas mixture, containing both nitrogen and sulfur oxides, only the nitrogen oxides are oxidized by ozone. Contrary to earlier results, sulfur dioxide does not disturb the oxidation of nitrogen oxides under dry conditions. The consumption of ozone in the oxidation of nitric oxide was slightly below the stoichiometric level because the ozone was introduced into the reactor in the oxygen flow. When the molar ratio between ozone and nitric oxide was more than 0.4, some of the nitric oxide was oxidized to higher oxides of nitrogen, the final product being a solid mixture of N2O5 and (NO)2S2O7. Some nitrosyl sulfuric acid was formed in the aqueous solution of hydrogen peroxide in addition to sulfuric acid under wet conditions. Some white solid was found on the walls of the reactor. This solid is said it the literature to consist of H2SO4, HNOSO4 and (NO)2S2O7.
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    Chemical Engineering & Technology - CET 20 (1997) 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Chemical Engineering & Technology - CET 20 (1997), S. 564-570 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The modern urea plants are using a stripping process to reduce the energy consumption. The potential, very severe corrosion problems have been mastered by special grades and strict process control. The different grades are reviewed. After more than 20 years operation the results are very satisfying.In ammonia plants, an often forgotten corrosion problem is found in the heat exchangers. After about 3-6 years failures caused by chloride continuing cooling water may appear on carbon steel or low alloyed austenitic stainless steels. Corrosion mechanism is reviewed. Duplex stainless steels has been used with success and the properties are presented. An example of life-cycle cost shows that duplex stainless steel is an inexpensive way to solve chloride related corrosion problems.Condensation and evaporation of nitric acid in heat exchangers in nitric acid plants cause severe corrosion on conventional stainless steel grades. Low impurity in combination with high chromium content has proved to result in stainless steel with improved corrosion resistance.
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  • 58
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    Chemical Engineering & Technology - CET 20 (1997), S. 550-556 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bubble break-up, gas holdup, and the gas-liquid volumetric mass transfer coefficient are studied in a bubble column reactor with simultaneous injection of a gas and liquid through a T-junction nozzle. The theoretical dependence of bubble break-up and the volumetric mass transfer coefficient on liquid velocity in the nozzle is developed on the basis of isotropic turbulence theory. It is shown that correlations which are developed based on liquid jet kinetic power per nozzle volume explain average gas holdup and the volumetric mass transfer coefficient within an error of 15% for all gas and liquid flow rates and nozzle diameters used. Experiments with a larger scale column, height 4.64 m and diameter 0.98 m, show a transition from homogeneous to heterogeneous flow at a certain liquid flow rate through the nozzle. Liquid composition was found to have a significant effect on gas-liquid mass transfer. A phenol concentration of 10-30 mg/l in water increases the volumetric mass transfer coefficient of oxygen by 100%. This phenomenon may have significance in the chemical oxidation of wastewater.
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    Chemical Engineering & Technology - CET 20 (1997) 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Chemical Engineering & Technology - CET 20 (1997), S. 582-588 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The shape-selective transalkylation of biphenyl with pentamethylbenzene over ultrastable Y-faujasites to produce para-methylated biphenyls was studied in the liquid slurry phase. The reaction was carried out in a discontinuously operated stainless steel autoclave using n-heptane as the solvent with a temperature range of 513 to 533 K and a pressure of 3 MPa. As for the progress of the reaction the presence of strong Brønsted acid sites was essential, an ultrastable faujasite treated with aqueous hydrochloric acid having a high content of those sites was used as the catalyst. Thus, a yield of the target product 4,4′-dimethylbiphenyl of above 11% referring to biphenyl could be achieved. The effect of the operating conditions on the formation of the target product was investigated. The decisive influence was acted out by the molar ratio of biphenyl to alkylating agent, in so far as a surplus of pentamethylbenzene of 7:1 referring to biphenyl enhanced the yield of the target product to 14%. The kinetics of the reaction could be successfully descibed with a lumped reaction scheme, introducing pseudo components, summarizing structural isomers, and pseudo reactions, such as the formation of coke.
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    Chemical Engineering & Technology - CET 20 (1997), S. 624-632 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The oxidation of sulfide in oxygen-saturated aqueous solutions is accelerated by dissolved or silica-bonded cobalt phthalocyanines. On the basis of thermodynamical considerations it is postulated that the catalyst enhances the formation of disulfide as the initial elementary reaction step. The following reaction steps are largely unaffected by the catalyst, as indicated by a product ratio sulfate/thiosulfate=0.86, comparable to that of the uncatalyzed autoxidation. A Langmuir-Hinshelwood formalism is developed for the catalytic reaction step and is demonstrated to fit best with the kinetics. In addition, from the kinetic data free enthalpies for the adsorption of HS- (i) at the dissolved phthalocyanine (ΔG = -17.6 kJ/mole) and (ii) at the immobilized complex (ΔG = -20.0 kJ/mole) are calculated.
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  • 62
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    Chemical Engineering & Technology - CET 20 (1997), S. 641-645 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An In-HZSM 5 honeycomb catalyst is used for the experimental investigations of the NO reduction with methane. The catalyst is prepared by the ion-exchange method. The influence of temperature and concentration of oxygen and methane is studied. In addition to methane, natural gas is used as reductant for the reduction of nitric oxide. The results are compared with those of other authors who use zeolithe pellets.
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  • 63
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chemical engineering is taught at German universities in three different types of curricula: chemical engineering proper, process engineering (“Verfahrenstechnik”), and industrial chemistry (“Technische Chemie”). Independent departments resp. faculties of chemical engineering exist at four universities. At other universities process engineering is offered as a complete curriculum with a smaller amount of chemistry than chemical engineering curricula, mostly by the departments of mechanical engineering. Industrial chemistry is an essential component of chemistry courses at most technical universities and optional subject at several classical universities. The cause of this diversity of approaches to chemical engineering can be traced back to the beginning of the production of high-value organics (dyes, pharmaceuticals) in Germany in the second half of the 19th century.
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  • 64
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    Chemical Engineering & Technology - CET 20 (1997), S. 293-296 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When mechanical foambreakers are used in chemical engineering processes to control an undesired primary foam, a secondary foam is often produced. Secondary foams consist of small bubbles, have a high liquid hold-up, and cannot be condensed further by mechanical foambreakers. Secondary foams can be converted into liquid and gas in a coalescence column by drainage, diffusion, and breakage of the lamellas. This paper presents a new model to determine the velocity of bubble growth and the time of coalescence of secondary foams. The experimental investigations have been carried out with surfactants in aqueous solutions.
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  • 65
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    Chemical Engineering & Technology - CET 20 (1997), S. 309-312 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Errors caused by the use of sensitivity tables may become very large in some cases because of the tables' total disregard of nonlinearities and interaction effects. We introduce a new and improved approach which calculates the effect of disturbances simultaneously by solving a set of linear equations. The approach offers simplicity, speed, insight and accuracy.
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  • 66
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A ‘carbon source controlled shift technique’ was developed for fermentation medium optimization in continuous culture with the objective to maximize growth rate and growth-linked product formation of a biological system. An automatic culture medium preparation system was operated together with 2 parallel stirred tank reactors and a HPLC system for on-line analysis of the carbon source concentration in the reactors. A genetic algorithm was applied for experimental design. The concentrations of 7 medium components (mineral salts and vitamins) were optimized automatically within 40 continuous experiments to result in a maximum growth rate of the methylotrophic yeast Candida boidinii and growth-linked production of the formate dehydrogenase enzyme (FDH). The specific growth rate of Candida boidinii and the specific activity of the FDH enzyme at a set-point of 420 mM methanol in the reactor were, thus, improved by 19% to 0.16 h-1 and 26% to 164 U g-1, respectively, compared to the previously used medium, which has already been previously optimized in shake flask experiments. The results of the continuous medium optimization were evaluated with a full second order seven-dimensional polynomial model (regression coefficient 96.8%).
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  • 67
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    Chemical Engineering & Technology - CET 20 (1997), S. 414-418 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the present work, we employ a fuzzy logic controller (FLC) to control the unstable state of a nonlinear biological reaction. The state variable vectors consist of cell density and substrate concentration. The dilution rate is used as a manipulated variable to control the reaction dynamics. An analytic form of FLC employing Zadeh AND logic along with Center of Mass defuzzification method is considered. Simulations reveal that for servo response test, the FLC shows satisfactory performance for natural unsteady states for which a conventional PI controller is known to fail. Further simulations also show that the FLC gives satisfactory regulatory response and is relatively insensitive to the deviations in model parameters.
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  • 68
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    Chemical Engineering & Technology - CET 20 (1997), S. 429-433 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When in contact with water, organoalkoxysilanes and other alkoxy metal compounds react to organofunctionalized polysiloxanes or heteropolysiloxanes. A new method for the continuous preparation of porous organopolysiloxane spheres was developed. Droplets of the precursor mixture are injected into the vertical reactor column. Movement of the gelating droplets is controlled by flow of the aqueous reaction medium. Advantages are adjustable residence time, minimized coalescence and low reactor height. An example shows typical product characteristics like narrow particle size distribution and macroporosity.
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  • 69
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    Chemical Engineering & Technology - CET 20 (1997), S. 462-468 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The autoxidation of aqueous sulfide solutions by dioxygen is studied at pH 9 and 14 and at initial sulfide concentrations between 1 and 100 mM. Disulfide as a primarary intermediate is proposed to enhance the sulfide oxidation by autocatalytically forming polysulfies. The postulate is supported by the observed acceleration of the process at increasing pH favoring the presence of disulfide rather than that of sulfur. The final reaction products thiosulfate and sulfate are proposed to result from the hydrolysis of the highly instable intermediate polythiosulfite in parallel parallel reaction pathways, assuming probabilities for breaking the sulfur chain at the α (sulfate) and β (thiosulfate) positions to be responsible for the selectivity. A reaction scheme is proposed, considering all experimental observations.
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  • 70
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    Chemical Engineering & Technology - CET 20 (1997), S. 485-490 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic model of the liquid fluidized bed containing two or more solid particle species of different size and density is presented. The model incorporates the particle mass transport mechanisms of the convection and the dispersion. The movement of the upper interface of the bed subject to a change in the liquid velocity is specified using the mass balance constraint. The particle velocities and dispersion coefficients are evaluated using correlations. The model is capable of describing the bed expansion, concentration profiles of the individual particle species, the bulk density profile, and the occurrence of layer inversion.
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  • 71
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    Chemical Engineering & Technology - CET 20 (1997), S. 221-229 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To review mass transfer trays from a process point of view, the dependence of efficiency on the loadings, the loading range and the maximum loadings with an acceptable tray efficiency have to be known. Comparing the results taken from experiments on Dualflex trays and from other types of trays which have been in industrial applications for many years and which are recognized as “industrial standard”, has been evaluated in this review.
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  • 72
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    Chemical Engineering & Technology - CET 20 (1997), S. 259-267 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, a scale-down approach has been used for the simulation of the imperfect mixing on the growth processes by considering several configurations of continuous stirred tank reactor (CSTR, aerated) and plug flow tubular reactor (PFTR, not aerated). The steady-state concentrations of biomass and enzyme in a continuous culture were calculated as a function of dilution rate using modified Monod growth kinetics. A mathematical model for each combination of two bioreactors was developed to account for growth, substrate utilization (oxygen and glucose) and enzyme synthesis and decay. The model was then used to investigate biomass production and enzyme expression in relation to the volumetric fraction Uf = VPFTR/(VCSTR + VPFTR) and the recirculation ratio R = fr/(f + fr) of the fermentation system. These two mixing parameters were found to be significant factors in the biomass and enzyme production from the fermentation system. This model was also compared with some of the existing models.
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  • 73
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    Chemical Engineering & Technology - CET 20 (1997), S. 23-28 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the present study, a mass transfer model for Type-1 facilitated transport in liquid surfactant membrane is developed by taking into consideration a size distribution of emulsion drops, and analytical solution of the model equations has been presented. The model takes into account the continuous phase and outer liquid membrane phase resistances along with diffusion through composite emulsion drop. Effort has been made to highlight the effect of the various system parameters on the extraction rate including computation of reaction front position. The results of this work are found to be in good agreement with the published experimental results on batch extraction of phenol using NaOH as internal reagent. The model would thus provide an insight of the separation mechanism involved in the mass transfer processes in this type of system.
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  • 74
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    Chemical Engineering & Technology - CET 20 (1997), S. 43-46 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid-phase cyclohexanone ammoximation over titanium silicate was carried out in a batch reactor. The influence of the solvent, duration of kinetic run, catalyst amount and reactant concentrations was investigated. Byproducts were formed in considerable amounts, leading to catalyst deactivation by pore blocking. The values of initial reaction rates were calculated taking into account deactivation phenomenon. Theses values indicated that within the range of studied concentration (Ccyclohexanone = 0.4 to 1.70 mol/l; Cammonia = 1 to 4 mol/l; Chydrogen peroxide = 0.4 to 1.8 mol/l) the reaction rates plotted as a function of all the reagent concentrations go through a maximum. Special experiments on hydrogen peroxide decomposition and cyclohexanone oximation by hydroxylamine demonstrated that the rates of these reactions are essentially higher than the ammoximation rates.A kinetic equation for initial ammoximation rates was developed on the basis of a mechanistic model. The advanced model permits description of the observed kinetic regularities.
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  • 75
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The following deliberations are concerned with the application of economy criteria to the optimization of process-engineering plants. We are therefore not concerned here with criteria for investment decisions, i.e., decisions on the implementation orabandonment of an investment project, nor with criteria for the selection of the most profitable investment options from a series of alternatives. Instead, we are interested here in the question of how a plant, while at the planning stage, can best be designed, i.e., the most rational method of selecting process parameters, such as throughputs, pressures, temperatures, concentrations, etc. The problem of plant optimization only occurs, however, when there are design parameters which can be selected at will or can, at least, be varied within certain limits. This is however, virtually always the case. There is then a need for an optimization strategy in the form of an objective function which is either reduced to a minimum, where lowest possible production costs are the target, for instance, or advanced to a maximum, where high profitability is the aim. The inclusion of engineering economy functions, in the form, namely, of the net present value function and the internal rate of return function for definition of such objective functions, provides better defined information on the best possible choice of process parameters than was possible with methods previosly used, such as the annuity method, for instance. One obtains different values for the process parameters to be optimized, depending on the objective functionused, and therefore different investment costs and utility consumptions. These differences are delineated and quantified using a process-engineering example in the course of the following discussion. The example selected is a gas scrubber, the function of which is to remove and recover useful components from a flow of gas. The specific problem examined is one of heat recovery.
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    Chemical Engineering & Technology - CET 20 (1997), S. 90-92 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of sodium lauryl sulphate (anionic) and Triton X-100 (nonionic) on the solid-liquid mass transfer at a gas-sparged fixed bed of copper Raschig rings was studied by measuring the diffusion-controlled dissolution of copper rings in acidified chromate solution. The variables studied were the nitrogen flow rate, the type of surfactant, and the surfactant concentration. It was found that an increase occurs in the solid-liquid mass transfer coefficient with increasing the nitrogen flow rate. Increasing the surfactant concentration was found to decrease the mass transfer coefficient. For a given surfactant concentration, it was found that Triton X-100 reduces the mass transfer coefficient more than sodium lauryl sulphate.
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  • 77
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    Chemical Engineering & Technology - CET 20 (1997), S. 118-130 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic model is developed for a fluid catalytic cracking (FCC) unit to describe the dynamic behavior of both the riser and the regenerator reactors and their interactions. The cracking reactions are simulated by the four-lumped kinetic model [1]. The reactions in the riser occur in a transported bed with the fluid and the solids in ideal plug flow. The two-phase nature of the regenerator-fluidized bed is considered and the kinetic model for the coke combustion on the cracking catalyst [2,3] is incorporated. The proposed model is validated using steady-state plant data from an industrial unit and the results are found to be in good agreement. One of the main advantages of the model is that it does not include any partial differential equations. This facilitates the solution of the equations and makes the model particularly suitable for control studies. Simulation studies are performed to investigate the effect of changing various process variables, such as catalyst circulation rate, gas oil feed rate, and oxygen feed concentration.
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    Chemical Engineering & Technology - CET 20 (1997) 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Chemical Engineering & Technology - CET 20 (1997), S. 182-191 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The uncatalyzed esterification of acetic acid is described in the literature as a typical example of reactive distillation. Many rigorous models were validated using this esterification as an example. Process proposals for the production of pure ethyl acetate from ethanol and acetic acid have been determined using short-cut methods with the assumption of chemical equilibrium only. In this publication, the limitations of this esterification are clarified, using a rigorous model that was developed. The reasons why reactive distillation appears to be unfavorable for this esterification are explained. It is, however, theoretically possible to obtain ethyl acetate in high purity with different variants of the process. Different process variants are examined in this work. Construction variables that are important for the design of reactive columns, such as the number of reactive separation stages and the holdup in the column, are analyzed. Furthermore, the influence of variables dependent on the component system, such as the phase equilibrium of the reactive system and the reaction kinetics on the conversion in the column, are described. It can be shown that the short-cut methods published so far for reactive distillation, which assume chemical equilibrium, are inadequate.
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    Chemical Engineering & Technology - CET 20 (1997), S. 203-207 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Transient heat transfer in a mechanically agitated vessel is studied in the case of an anchor and an helical ribbon impeller using Newtonian and shear thinning fluids. Temperature stratification is found more pronounced with the anchor, making this impeller clearly inadequate for heat transfer. The impact of natural convection is evaluated first using the classical Gr/Re2 ratio. It is shown that the use of this criterion in viscous mixing is somewhat misleading. A new Grashof number is then proposed to assess the significance of the viscous and buoyancy effects in non-isothermal, non-Newtonian mixing applications. It is shown that the interpretation of this new number is strongly related to the concept of process viscosity.
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    Chemical Engineering & Technology - CET 20 (1997), S. 240-246 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rate of the homogenous exothermic hydrolysis reaction of acetic anhydride catalyzed by sulfric acid in solvent acetic acid was estimated from nonisothermal experimental batch reactor transient temperature data. Rate equations based on three different reaction mechanisms of hydrolysis published in the literature were fitted to the experimental rate data. The experimental results on runaway and limit cycle behavior obtained with this reaction were explained by using the mechanism-based rate equations for hydrolysis in the reactor dynamic models, and good agreement was obtained between the predicted and the experimental dynamic data.
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    Chemical Engineering & Technology - CET 20 (1997), S. 282-284 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Chemical Engineering & Technology - CET 20 (1997), S. 268-276 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As an alternative to the existing bioheat transfer models a new system of two energy equations is proposed by considering the human body as a deformable porous medium. One equation is developed for the blood and the other for the peripheral skeletal tissue. It includes such significant factors as the vascular geometry and size, the blood flow and direction, thermal diffusion and the local thermal nonequilibrium between the blood and peripheral tissue. Discussion and application of both equations are given.
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    Chemical Engineering & Technology - CET 20 (1997), S. 285-286 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An ortho-experiment design and the analysis method of mathematical statistics are adopted to study the conversion of gypsum and potassium chloride to potassium sulfate in the system of K+, Ca2+, NH4+ ‖ Cl-, SO42- in H2O. Optimal reaction parameters and engineering mean are acquired to attain a conversion yield of potassium chloride of 94.52%.
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    Chemical Engineering & Technology - CET 20 (1997), S. 297-303 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Electrochemical gas absorption or biotechnical purification processes using structured packing as electrode or as biological support, respectively, may operate in bubble columns in presence of suspended solids. In both systems the knowledge of mass transfer rates from the liquid to the packing is important for the design of equipment. In the present investigation, the fluid dynamic behavior of a simple bubble column and a bubble column containing small size particles, both in presence of structured packing, was studied. Furthermore, mass transfer coefficients between the liquid and the structured packing were obtained by the electrochemical method. The influence of physical properties of the liquid phase, gas flow rate, kind and concentration of the suspended particles on both gas holdup and mass transfer was investigated. Correlations of the experimental data of mass transfer using dimensionless groups were derived and compared to previous correlations. Similarity with a heat transfer expression already used in two-phase systems was found.
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    Chemical Engineering & Technology - CET 20 (1997), S. 333-337 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reaction of anisole hydroxylation with hydrogen peroxide to form methoxyphenols over TS-1 was studied. Four C1-C3 alcohols and the two aprotonic solvents acetone and acetonitrile were used. Product conversion was almost proportional to the titanium content of the catalyst sample. The highest conversion and p-selectivity were observed in ethanol. Some speculations, based on the formation of substrate-solvent or titanium-solvent-oxidant complexes, about the role of the solvent are presented. It was found that in all the solvents studied the p/o ratio increased with time.
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    Chemical Engineering & Technology - CET 20 (1997), S. 378-383 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Catalytic decontamination of waste gases in a fixed bed reactor, operating at non-steady state conditions achieved by periodic gas flow reversal, is simulated on the basis of a mathematical model. The opportunity to utilize a significant part of the reaction heat is discussed and the effect of catalyst inactivation upon reactor performance is analyzed. Stable temperature regime and conversion exceeding 99.5% could be ensured by a more than eightfold reduction of catalyst activity.
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    Chemical Engineering & Technology - CET 20 (1997), S. 396-402 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A packed column has been used to study the absorption of nitrogen oxide in an alkaline solution of potassium permanganate. The reactions taking place during the absorption have been examined and the rate constants have been estimated from experimental data. The experiments show that potassium permanganate is an excellent absorbent for nitrogen oxide. However, to avoid formation of MnO2, the hydroxide concentration has to be very high, i.e. 〉 3 mol/l. It was found that the reaction could be expressed as first-order with respect to NO and with respect to KMnO4. The rate constant may be expressed in terms of the hydroxide concentration as follows: kmn = 6114.9 101.9208 10-4 CNaOH m3 mol-1 s-1.
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    Chemical Engineering & Technology - CET 20 (1997), S. 424-428 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In paper coating make-down, a poor dispersion of pigments in coating colors may lead to coater runnability problems. This is manifested by coat defects at the paper surface, excessive coater blade wear, and an over-consumption of pigments. For this reason, high shear impellers operated at high speed are used, yielding a high energy consumption. A new method to disperse high solids mix at low energy consumption is presented. This method based on the use of a rod impeller scraping the fluid surface in the vessel, is tested on a slurry composed of calcined and delaminated clays up to a solids content of 66.7 wt.% without dispersing aids.
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    Chemical Engineering & Technology - CET 20 (1997), S. 445-454 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two different layouts for the liquid-liquid extraction section of an industrial caprolactam process are evaluated. Laboratory mass transfer measurements on streams obtained from an industrial and a demonstration plant with different extraction sections are interpreted by a model describing the effect of surface contaminants on mass transfer coefficients. Indications of the impact of these layouts on the complexity of the extraction section, quality of products and efficiency of the extraction processes are given.
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    Chemical Engineering & Technology - CET 20 (1997), S. 469-474 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bubble columns are commonly used in industry for polluted gas treatment. Based on the same principle, the droplet column which is not widely known in the literature, uses much higher gas velocities, up to 14 m/s. This study concerns the hydrodynamics and mass transfer in this apparatus, in presence or absence of solid particles. Our results have demonstrated the impact of dusts on mass transfer performance giving rise to an increase in the kL aL coefficient with decreasing particle size. However, no influence of dust on the hydrodynamics of the column has been demonstrated within the studied particle size range.A study of liquid holdups obtained by three different methods is also carried out. Our results are comparable, thus validating the methods used.
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    Chemical Engineering & Technology - CET 20 (1997), S. 491-494 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments were carried out in a conventional circulating fluidised bed to measure the axial pressure profile and total pressure drop, which covered a wide range of operating conditions. Material belonging to the Geldart A (fine material) as well as the Geldart B (course material) categories have been used in the present work. Slip velocity is determined from the total pressure drop and noticed that the slip velocity is much higher than the free fall velocity of single particle for Geldart A type material, while it is approximately equal to the free fall velocity of single particle for the Geldart B type materials.A model is developed for slip velocity taking into account all the hindrance effects: particle-particle, and particle-wall, and particle agglomeration. Predictions of the present model are validated with the data due to present study and the data reported in the literature.
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    Chemical Engineering & Technology - CET 20 (1997), S. 502-509 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dust explosion hazard exists in plants and facilities wherever combustible dusts are hardled. Minimum explosible concentration of dust clouds is an important factor requiring special attention for hazard evaluation if any technological equipment is to be protected by inertisation. The mathematical models available for prediction of this parameter have been analysed for their application to organic dust clouds. Solution of the most general mode for determination of minimum explosible concentration of dust clouds proposed by Mitsui and Tanaka is presented, together with the comparison with experimental data. It has been found that the model is not successful in predicting the minimum explosible concentration for organic dusts. Recommendations on requirement of development of a new model for prediction of minimum explosible concentration of an organic dust such as polyethylen have been given.
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    Chemical Engineering & Technology - CET 20 (1997), S. 557-563 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Capillary viscometry is used to characterize viscosity, entrance pressure loss and apparent wall slip of paper coating colors at high shear rates. Special emphasis is laid on the dependence of these phenomena on solids content in order to account for changes in the rheology due to the dewatering of the color during the coating process. Coating colors with substantially different runnability have been investigated. Differences in apparent wall slip and high shear viscoelasticity (manifesting itself in extremely high entrance pressure losses) are observed at increased concentration, even if these phenomena do not show up at the initial solids content. Poor runnability is observed when viscosity, entrance pressure loss and wall slip increase strongly with increasing solids content. But all rheological features change simultaneously with the coating color recipe and it is not possible to separate out the contribution of the particular rheological features on the runnability of the coating colors or to correlate the runnability to a single rheological prorameter. Future work will have to focus on a numerical analysis of the blade coating process taking into account all the rheological features described here. First simulations including slip at the color/blade interface indicate that wall slip may cause severe runnability problems, at least when the apparent slip velocity exceeds the web velocity.
    Additional Material: 9 Ill.
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  • 95
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 581-581 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 96
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 589-595 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New data of gas-liquid mass transfer for cocurrent downflow through packed beds of non-porous particles are presented. Mass transfer parameters for air/carbon dioxide/water and air/carbon dioxide/sodium hydroxide systems were evaluated by least squares fit of the calculated CO2 concentration profiles in the gas phase to the experimental values. The dependence of kGa on gas and liquid flow rates is caused by the dependence of gas-liquid interfacial area, not by the gas-side mass transfer coefficient kG. In the case of the absorption of dilute carbon dioxide the gas-side resistance is considerably smaller than the liquid-side resistance. In the pulse flow regime, gas-liquid interfacial area calculated from kLa and kL values obtained by physical, respectively, chemical absorption are lower than the gas-liquid interfacial area evaluated from the measurements under reaction conditions.
    Additional Material: 10 Ill.
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  • 97
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 617-623 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Designing an appropriate methanol steam reformer requires detailed knowledge about the processes within such a reactor. Thus, the axial temperature and concentration gradients and catalyst ageing were investigated. It was found that for a fresh catalyst load, the catalyst located in the reactor entrance was most active during the experiment. The activity of this part of the catalyst bed decreased after some time of operation due to ageing. With further operation, the most active zone moved through the catalyst bed. From the results concerning hydrogen production and catalyst degradation, the necessary amount of catalyst for a mobile PEMFC-system can be estimated.
    Additional Material: 7 Ill.
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  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 633-640 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The size-dependent breeding of sodium chlorate crystals can be determined by carrying out experiments with seed crystals of optical antipodes of different sizes that undergo absolutely identical experimental conditions. Small portions of right- and left-handed seed crystals of different sizes were used. The number density distributions of the two opposite forms led to the total numbers of D- and L-crystals. The nucleation from different seed sizes under identical experimental conditions was found to be proportional to L4 in agreement with Clontz et al. [1] and Bennett et al. [2]. A computer program for the modelling of batch crystallization was used to calculate the development of the nucleation process. The data for the supersaturation course and for the development of the population of the right- and left-handed crystals are in good agreement with the experimental results. Only few generations (one or two) of secondary nucleation are being built during the process because of the strong influence of the size of crystals on the nucleation rate. The formation of two generations of secondary nuclei could be observed during three-hour batch crystallization runs.
    Additional Material: 11 Ill.
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  • 99
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 14 (1997), S. 283-289 
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of the surface roughness of solid conducting spheres on the response of a phase-Doppler anemometer (PDA) is described by using a ray theory model. A rough particle surface is modeled as an ensemble of distorted spheres. First- and second-order reflection and diffraction are considered for far-field calculations of the PDA phase difference. The numerical simulations are accompanied and supported by experimental results. Single rough Sn spheres are captured inside an electro-dynamic trap and investigated with a standard phase-Doppler system.
    Additional Material: 11 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 14 (1997), S. 295-303 
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method is introduced to analyze the accuracy of phase-Doppler anemometry (PDA) for sizing large particles in two-phase flows. The method is based on Fourier optics theory (FOT) and geometrical optics theory (GOT) to calculate the intensity ratio of refractive and reflective light scattered by a sphere under a slit constraint. To examine the accuracy in calculating the light intensity, the results from the GOT method were compared with those of the direct simulation based on the generalized Lorenz-Mie theory (GLMT). This newly developed FOT/GOT method also predicts the results of phase jump due to the slit constraint. The performance of dual-mode phase-Doppler anemometry can also be simulated by this method.
    Additional Material: 17 Ill.
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