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  • 1
    ISSN: 1573-5133
    Keywords: Batoidea ; Chondrichthyes ; Elasmobranchii ; Amazon ; Magdalena ; Maracaibo ; Orinoco ; Paraná-Paraguay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The number of venomous caudal spines and their length and position relative to one another were determined in seven species of South American freshwater rays (Potamotrygonidae) and eight marine or euryhaline species of four families from the Caribbean Coast of South and Central America. Most species have two visible spines at certain stages in the shedding-replacement cycle and only one visible spine at other stages (following shedding). If we include the embryological beginnings of the spines before they erupt and become visible, the spine counts of most rays are actually 2 rather than 1 or 2. Since most species apparently follow this pattern, spine counts are of little use in distinguishing between species except in the relatively few that may have only one, or no spines. Eight captive Potamotrygon specimens maintained in simulated tropical temperature conditions over 12 months showed periodic shedding and replacement of spines. The molts were biannual for a given ray but annual for a given spine. They alternated between two spine loci and their cycles were approximately six months out of phase with each other. Recent studies on Dasyatis sabina by others report only one molt per year, with replacement spines forming always posterior to the primary spine rather than alternating between posterior and anterior. Supernumerary spines (counts of more than two, up to five) are also discussed, as are counts of one and zero.
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  • 2
    ISSN: 1573-5133
    Keywords: Elasmobranchii ; Euryhalinity ; Freshwater adaptation ; Dam lake ; Osmoregulation ; Central America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The Río Bayano in eastern Panama is one of many tropical rivers in which bull sharks (Carcharhinus leucas) and largetooth sawfish (Pristis perotteti) have been known to occur. Since both species can osmoregulate in fresh water throughout life, theoretically, both could survive in landlocked situations for many years.P. perotteti reproduces in fresh water, butC. leucas ordinarily does not, so only the former would appear to have the potential for establishing a breeding stock in such a landlocked freshwater body. The damming of the Rio Bayano and the creation of a large impoundment in 1976 provides a test of the ability of members of both species trapped there to survive and to establish breeding stocks. In 1980 and 1981 three mature femaleC. leucas were found dead in Lake Bayano and three sub-adult femaleP. perotteti were taken by trammel net. These events confirm the ability of both to survive in fresh water for long periods, but the establishment of breeding stocks appears doubtful and the question may not be answered for many years.
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  • 3
    ISSN: 1573-5133
    Keywords: Amazonia ; Batoidea ; Brazil ; Captive breeding ; Chondrichthyes ; Colombia ; Elasmobranchii ; Freshwater adaptation ; Growth rate ; Potamotrygonidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Observations of reproductive features and body measurements were made on wild-caught, freshwater stingrays, Potamotrygon circularis and P. motoro, from the Amazon drainage of western Brazil and southern Colombia. Further observations were made in Detroit's Belle Isle Aquarium on a captive pair of P. motoro and their descendants, which constitute the first known captive breeding colony of potamotrygonids. The gross structure and function of female and male reproductive systems are described. There is no obvious difference between those of the two species. They are aplacentally viviparous, the young being nourished in advanced stages by uterine milk secreted by trophonemata. Size at onset and completion of sexual maturation, breeding season and behavior, gestation period, litter size and sex ratios are discussed. Up to 21 proportional measurements were made on several fetal and postnatal stages of both species. Several proportional changes occur in very early fetal life, but most body proportions undergo only minor changes from advanced fetal through adult stages. A growth curve is proposed for P. motoro based on observations of the captive colony.
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  • 4
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N.M.R. Spectroscopic Investigations of Thiophosphazenes. I. Reactions of Sodium Ethylthiolate with Hexachlorocyclotriphosphazatriene and OctachlorocyclotetraphosphazatetraeneBy reactions of hexachlorocyclotriphosphazatriene with an excess of sodium ethylthiolate as a suspension in ether all of the possible geminal derivatives N3P3Cl6-n(SEt)n; n = 1-6, are formed in different quantities. Products from reactions of octachlorocyclotetraphosphazatetraene with sodium ethylthiolate, N4P4Cl8-n(SEt)n, likewise contain all of the geminally substituted derivatives up to n = 8 with the exception of the derivatives with n = 1 and n = 7. Compounds with n = 3, 4, or 5 exist in two geminal isomers respectively. Nongeminal ethylthiochlorophosphazenes were not found by any reaction. The formed compounds were isolated by chromatographic methods and studied by 31P n.m.r. spectroscopy.
    Notes: Bei Umsetzungen von Hexachlorocyclotriphosphazatrien mit einem Überschuß an Natriumethylmercaptid in etherischer Suspension entstehen in unterschiedlichen Mengen alle denkbaren geminalen Substitutionsprodukte N3P3Cl6-n(SEt)n; n = 1-6. Im Reaktionsprodukt des Octachlorocyclotetraphosphazatetraens mit Natriumethylmercaptid, N4P4Cl8-n(SEt)n, lassen sich außer den Verbindungen mit n = 1 und n = 7 ebenfalls alle geminalen Substitutionsprodukte biz zu n = 8 nachweisen, wobei sich für die Verbindungen mit n = 3, 4, 5 jeweils beide geminalen Isomeren bilden. Nichtgeminale Mercaptochlorophosphazene waren bei keiner Umsetzung nachweisbar. Die entstandenen Verbindungen wurden säulenchromatographisch isoliert und 31P-NMR-spektroskopisch untersucht.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 490 (1982), S. 121-128 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: NMR Spectroscopic Studies of 15N Labelled OxocyclophosphazanesThe completely 15N labelled cyclophosphazanes (15NMeP(OMe)O)3, (15NEtP(OEt)O)3, and (15NMeP(OMe)O)4 were prepared by rearrangement of the corresponding alkoxyphosphazenes and their 31P- and 15N-NMR spectra were investigated. On the case of the trimer compounds spectra of the ABB′XX′Y spin type were obtained; all coupling constants are relevant, and like the 15N chemical shifts they are found only by means of spectra simulations. The relative signs of the coupling constants 1JPN, 2JPP, 2JNN, and 3JPN were also obtained.
    Notes: Die vollständig 15N-markierten Cyclophosphazane (15NMeP(OMe)O)3, (15NEtP(OEt)O)3 und (15NMeP(OMe)O)4 wurden aus den entsprechenden Alkoxyphosphazenen dargestellt und sowohl 31P- als auch 15N-NMR-spektroskopisch untersucht. Bei den trimeren Verbindungen wurden Spektren vom Spintyp ABB'XX'Y erhalten; alle Kopplungskonstanten sind relevant, sie können wie die 15N-chemischen Verschiebungen nur auf dem Wege der Spektrensimulation erhalten werden. Es ergeben sich auch die relativen Vorzeichen für die Kopplungskonstanten 1JPN, 2JPP, 2JNN und 3JPN.
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  • 6
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N.M.R. Spectroscopic Studies of 15N Labelled N-Phosphorylphosphazenes and Imidodiphosphoric Acid Derivatives15N labelled compounds were prepared and investigated by means of 31P- and 15N-NMR spectroscopy. The chemical shift values δP and δN, and the coupling constants 1JPN and 2JPP are discussed and interpreted qualitatively by semiempirical quantumchemical calculations (CNDO/2) using POPLE'S ΔE-model.
    Notes: 15N-markierte Verbindungen der Substitutionsreihen wurden synthetisiert und mit Hilfe der 31P- und 15N-NMR-Spektroskopie untersucht. Die chemischen Verschiebungen δP und δN sowie die Kopplungskonstanten 1JPN und 2JPP werden diskutiert und qualitativ mit Hilfe halbempirischer quantenchemischer Rechnungen (CNDO/2) im Rahmen des POPLE-schen ΔE-Modells interpretiert.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 525 (1985), S. 7-13 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: NMR Spectroscopic Studies of 15N Labelled N-Methyl-imidodiphosphoric Acid Derivatives15N labelled compounds (EtO)mCl2-m(O)P—NMe—P(O)(OEt)nCl2-n (m = 0-2, n = 0-2) were prepared as a mixture and investigated by means of 31P and 15N NMR spectroscopy. The chemical shift values δP and δN, and the coupling constants 1JPN and 2JPP are discussed and interpreted qualitatively by semiempirical quantumchemical calculations (CNDO/2) using POPLE'S ΔE-model.
    Notes: 15N-markierte Verbindungen der Substitutionsreihe (EtO)mCl2-m(O)P—NMe—P(O)(OEt)nCl2-n (m = 0-2, n = 0-2) wurden im Reaktionsgemisch synthetisiert und mit Hilfe der 31P- und 15N-NMR-Spektroskopie untersucht. Die chemischen Verschiebungen δP und δN sowie die Kopplungskonstanten 1JPN und 2JPP werden diskutiert und qualitativ mit Hilfe halbempirischer quantenchemischer Rechnungen (CNDO/2) im Rahmen des POPLE-schen ΔE-Modells interpretiert.
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Methyl-N-Diethoxyphosphorylamido Derivatives of Hexachlorocyclotriphosphazatriene. I. The Reaction of Hexachlorocyclotriphosphazatriene with Sodium N-Methylamidophosphoric Acid Diethyl Ester.The reaction of hexachlorocyclotriphosphazatriene with the sodium salt of 0, 0-diethyl-N-methylamido-phosphate in the molar ratios 1:1, 1:2, and 1:3 gives a mixture of partially substituted compounds. The N-methyl-N-diethoxyphosphorylamidoderivatives, N3P3Cl6-n[NCH3P(O)(OC2H5)]n (n = 1, 2, 3) were isolated in a pure form by preparative column chromatography. Compounds with a higher degree of substitution are not formed. The compounds are characterized by their molecular weights, elementary analysis, and TLC-Rf values.
    Notes: Die Reaktion von Hexachlorocyclotriphosphazatrien mit dem Natriumsalz des N-Methylamidophosphorsäurediäthylesters führt bei Raumtemperatur in den Molverhältnissen 1:1, 1:2 und 1:3 zu einem Gemisch partiell substituierter Verbindungen. Mit Hilfe der präparativen Säulenchromatographie konnten die N-Methyl-N-diäthoxyphosphorylamido-Derivate, N3P3Cl6-n[NCH3P(O)(OC2H5)2]n (n = 1, 2, 3); in reiner Form isoliert werden. Verbindungen höheren Substitutionsgrades wurden nicht erhalten. Die Verbindungen wurden durch ihre Molmassen, Elementaranalysen und die dünnschichtchromatographischen Rf-Werte charakterisiert und gesichert.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 437 (1977), S. 269-274 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation and Constitution of a Heterocyclic Phosphorus BetaineThe zwitter ionic 2,2,6,6-tetrakis(diethylamido)-4,4-Dioxo-1,3,5,2λ5,4λ5,6λ5-azadioxatriphosphorin (3) is formed as a cristalline byproduct in the reaction of octaethyl imidodiphosphoryl tetramide derivatives, {[(Et2N)2P(O)]2N}Y (Y = H, Na, SiMe3), with phosphorus(V) chlorides (PCl5, POCl3, ClP(O)(OEt)2). It is obtained from the primary reaction products in a secondary reaction. Its constitution was revealed by 31P-n.m.r.-spectroscopy and by synthesis of the 15N-labeled compound. From O-Diethoxyphosphorylated octaethyl imidodiphosphoryl tetramide the compound 3 is obtained only in presence of water traces and agents providing HCl like e. g. ClSiMe3 or ClP(O)(OEt)2.
    Notes: Bei der Umsetzung von Octaäthylimidodiphosphoryltetramid-Derivaten, {[(Et2N)2P(O)]2N}Y (Y = H, Na, SiMe3), mit Phosphor(V)-chloriden (PCl5, POCl3, ClP(O)(OEt)2) entsteht aus den primären Reaktionsprodukten in einer Folgereaktion das zwitterionische 2,2,6,6-Tetrakis(diäthylamido)-4,4-Dioxo-1,3,5,2λ5,4λ5,6λ5-azadioxatriphosphorin (3) als kristallines Nebenprodukt. Die Konstitutionsermittlung erfolgte mittels 31P-NMR-Spektroskopie und durch Synthese der 15N-markierten Verbindung. Aus dem O-Diäthoxyphosphorylierten Octaäthylimidodiphosphoryltetramid bildet sich 3 nur in Gegenwart von Wasserspuren und HCl-liefernden Reagenzien, wie ClSiMe3 oder ClP(O)(OEt)2.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 448 (1979), S. 107-114 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N.M.R. Spectroscopic Investigations of Thiophosphazenes. II. N.M.R. Spectroscopic Investigations of 15N Labelled ThiophosphazenesCompletely 15N labelled compounds of the type 15N3P3Cl6-n(SR)n, R = Et or Ph; n = 0, 2, 4, or 6, and of the type 15N4P4Cl8-n(SR)n, R = Et; n = 0, 4, or 8, were prepared and investigated by means of both 31P n.m.r. spectroscopy and 15N n.m.r. spectroscopy respectively. The coupling constants 2JPP, in some cases only found by simulating the spectra, and the coupling constants 1JPN are given. The values of these coupling constants and their relation are discussed. The general tendency is visible, that with increasing coupling constant 1JPN the coupling constant 2JPP decreases. With increasing grade of substitution n the 15N chemical shifts are changed to higher fields.
    Notes: Vollständig 15N-markierte Verbindungen des Typs 15N3P3Cl6-n(SR)n, R = Et, Ph; n = 0, 2, 4, 6, und des Typs 15N4P4Cl8-n(SR)n, R = Et; n = 0, 4, 8, wurden synthetisiert und mit Hilfe der 31P-NMR-Spektroskopie und der 15N-NMR-Spektroskopie untersucht. Die Kopplungskonstanten 2Jpp, die in einigen Fällen nur auf dem Wege der Spektrensimulation gefunden werden, sowie die Kopplungskonstanten 1JPN werden angegeben und ihre jeweilige Änderung und ihr Verhältnis zueinander diskutiert. Es wird die allgemeine Tendenz sichtbar, daß bei zunehmender Kopplungskonstante 1JPN die Kopplungskonstante 2JPP abnimmt. Mit zunehmendem Substitutions-grad n ändern sich die 15N-chemischen Verschiebungen nach höherem Feld.
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