bluuebunny/crossref_metadata_2025 huggingface dataset:
1,2‐Bis(dimethylamino)‐3,4,5‐triphenyl‐3,4,5‐triphospha‐1,2‐diborolan und 1,2‐Bis(dimethylamino)‐3,4,5,6‐tetra‐tbutyl‐3,4,5,6‐tetraphospha‐1,2‐diborin: Synthese und Struktur sowie Berechnungen zur Molekülstruktur
Authors: Riegel B. , Hausen H.‐D. , Schwarz W. , Heckmann G. , Binder H. , Fluck E. , Dransfeld A. , Schleyer P. V. R.
Published: December 2004

Die Diphosphide K2[(C6H5)P(C6H5)PP (C6H5)], 4, bzw. K2[(tBuP)(tBuP)2P(tBu)], 5, reagieren mit (ClBNMe2)2 zu dem binären Fünfringsystem 1,2‐Bis(dimethylamino)‐3,4,5‐triphenyl‐3,4,5‐triphospha‐1,2‐diborolan (C6H5P)3(BNMe2)2, 2a, bzw. dem Sechsringsystem 1,2‐Bis(dimethylamino)‐3,4,5,6‐tetra‐tbutyl‐3,4,5,6‐tetraphospha‐1,2‐diborin, (tBuP)4(BNMe2)2, 3a. 2a und 3a konnten in reiner Form isoliert, NMR‐spektroskopisch und durch Röntgenstrukturanalysen charakterisiert werden. Beide Ringsysteme sind gefaltet; 2a zeigt eine „envelope”︁‐ 3a eine „Wannen”︁‐Konformation.

Ab initio Berechnungen an 3,4,5‐Triphospha‐1,2‐diborolan M5 zeigen, daß im globalen Minimum eine BP‐Doppelbindung mit annähernd planarem σ3‐Phosphor vorliegt. Die Geometrie der Stammverbindung des Sechsringes M6 weist „durch‐den‐Ring”︁‐Bindung in der PHBHBHPH‐Baugruppe auf, welche sich von jenen im Vier‐ und Fünfring M5 d unterscheidet. Durch die explizite Berechnung des Einflusses von Aminosubstituenten an Bor auf die Geometrien des Fünf‐ und Sechsringes verbessert sich die Übereinstimmung der Bindungslängen mit den Daten der Röntgenstrukturanalyse.
Neue Fluoride MIIIMIVF7 mit MIII = SE, Tl und MIV = Sn, Pb, Pt
Authors: Graudejus O. , Müller B. G.
Published: December 2004

Die farblosen Fluoride MSnF7 (M = La, Sm, Gd, Yb, Lu, Tl) und TlPbF7 sowie die gelben Verbindungen MPtF7 (M = Eu, Y, Lu) wurden erstmals in Form von Einkristallen oder mikrokristallin erhalten. Alle sind isotyp zu SmZrF7 (monoklin, Raumgruppe P21/c‐C2h5, Nr. 14; Aufstellung P21/n), mit Z = 4, mit

a = 1148,4(4), b = 573,1(3), c = 925,7(3), β = 107,83(4)°, LaSnF7;

a = 1124,9(4), b = 563,8(2), c = 905,3(3) pm, β = 107,35(3)°, SmSnF7;

a = 1119,3(2), b = 561,76(6), c = 898,36(9) pm, β = 107,40(1)°, GdSnF7;

a = 1098,5(2), b = 552,00(8), c = 876,5(2) pm, β = 107,58°, YbSnF7;

a = 1103,1(3), b = 547,4(2), c = 867,4(2) pm, β = 107,46(3)°, LuSnF7;

a = 1102,5(3), b = 546,5(2), c = 866,3(2) pm, β = 107,43(2)°, TlSnF7;

a = 1110,9(3), b = 552,1(2), c = 894,1(2) pm, β = 107,25(2)°, EuPtF7;

a = 1097,6(4), b = 546,0(2), c = 876,4(3) pm, β = 107,33(4)°, YPtF7;

a = 1090,0(5), b = 542,3(2), c = 866,8(4) pm, β = 107,46(4)°, LuPtF7;

a = 1138,6(4), b = 544,9(2), c = 876,5(3) pm, β = 107,27(3)°, TlPbF7.
Darstellung von Trifluormethylhalogen‐Iodaten(I) des Typs (CH3)4N+CF3IX− (X = F, Cl, Br) und Trifluormethyltrifluormethoxyiodat(I) (CH3)4N+CF3IOCF3−
Authors: Minkwitz Rolf , Bröchler Raimund , Berkei Michael
Published: December 2004

Es wird über die Darstellung einer Reihe neuer Iodate(I) des Typs CF3IX− (X = F, Cl, Br, OCF3) berichtet. (CH3)4N+CF3ICl− und (CH3)4N+CF3IBr− werden durch Additionsreaktion von CF3I an die entsprechenden Tetramethylammoniumhalogenide dargestellt. (CH3)4N+CF3IOCF3− erhält man durch Komproportionierung von (CH3)4N+CF3ICl− mit CF3OCl bei −78°C. CF3IF− entsteht sowohl, durch die Thermolyse von (CH3)4N+ CF3IOCF3− unter Abspaltung von COF2 bei −20°C, als auch durch Umsetzung von CF3I mit (CH3)4N+OCF3− bei −20°C.

Die thermolabilen Verbindungen werden durch IR‐, Raman‐sowie Multikern‐NMR‐Spektroskopie charakterisiert.
Beiträge zum thermischen Verhalten und zur Kristallchemie von wasserfreien Phosphaten. XV. Darstellung, Kristallstruktur und Eigenschaften von Kupfer(II)‐ultraphosphat CuP4O11 (≙ Cu2P8O22)
Authors: Glaum R. , Weil M. , Özalp D.
Published: December 2004

Die Synthese von CuP4O11 gelingt aus Cu2P4O12 und P4O10. In direkt anschließenden chemischen Transportexperimenten (600 → 500°C, Zusatz von Iod und wenigen mg CuP2 oder Phosphor als Transportmittel) werden wohlausgebildete, farblos‐transparente Kristalle mit Kantenlängen bis 4 mm erhalten (Transportrate ca. 2 mg/h).

Anhand von Röntgenbeugungsdaten eines pseudomeroedrisch nach (010) verzwillingten Kristalls konnte die Kristallstruktur von Kupfer(II)‐ultraphosphat (C1; Z = 8; a = 13,084(3) Å, b = 13,024(2) Å, c = 40,533(2) Å, α = 89,28(2)°, β = 118,42(2)°, γ = 90,30(2)°, Gitterkonstanten aus Guinier‐Aufnahmen) bestimmt und verfeinert werden (Volumenverhältnis 17/3; 3063 symmetrieunabhängige Reflexe mit 2θ ⩽ 53,4° und F ⩾ 4σ(F); 291 freie Parameter; konventioneller R‐Wert R1 = 0,038, wR2 = 0,101, GooF = 1,10).

Die Kristallstruktur enthält vier kristallographisch unterschiedliche zehngliedrige Polyphosphatringe ähnlicher Konformation, die zu zweidimensionalen Netzen parallel zu (−2 0 1) verknüpft sind. Kupfer ist auf zwei kristallographischen Lagen (Cu2P8O22) gestreckt‐oktaedrisch von Sauerstoff koordiniert (deq(CuO) ≈︁ (1,96 Å; dax(CuO) ≈︁ (2,34 Å).

Die Hauptachsen des g‐Tensors für CuP4O11 wurden an pulverförmigen Proben bestimmt zu g1 = 2,09, g2 = 2,24 und g3 = 2,36. Diese Werte stehen bei Annahme einer Austauschkopplung in sehr guter Übereinstimmung mit molekularen g‐Tensoren für die beiden unabhängigen CuO6‐Oktaeder (Cu2+(1): gx = 2,09, gy = 2,10, gz = 2,52; Cu2+(2): gx = 2,08, gy = 2,11, gz = 2,52) wie sie aus Berechnungen im Rahmen des „angular overlap model”︁ für CuP4O11 abgeleitet werden. Diese Betrachtungen geben auch das beobachtete Remissionsspektrum (4000–28000 cm−1) mit einer breiten Bande zwischen 7000 cm−1 und 13000 cm−1 sowie die magnetische Suszeptibilität μexp = 1,99 μB gut wieder.
Die Kristallstrukturen von SeCl3+SbCl6−, SeBr3+GaBr4−, PCl4+SeCl5− und (PPh4+)2SeCl42− · 2 CH3CN
Authors: Neumüller B. , Lau C. , Dehnicke K.
Published: December 2004

Die Kristallstrukturen der Titelverbindungen wurden röntgenographisch ermittelt.

SeCl3+SbCl6−: Raumgruppe P21/m, Z = 4, Strukturlösung mit 1795 beobachteten unabhängigen Reflexen, R = 0,022. Gitterkonstanten bei −80°C: a = 940,9; b = 1066,3; c = 1234,9 pm; β = 102,79°. Die Verbindung bildet Ionenpaare mit der Struktur eines flächenverknüpften Doppeloktaeders.

SeBr3+GaBr4−: Raumgruppe Pc, Z = 2, Strukturlösung mit 1461 beobachteten unabhängigen Reflexen, R = 0,058, Gitterkonstanten bei −60°C: a = 660,1; b = 655,3; c = 1431,3 pm; α = 101,17°. Die Verbindung kristallisiert im SCl3[AlCl4]‐Strukturtyp. Zwischen den Ionen bestehen zwei relativ kurze Se … BrGa‐Kontakte.

PCl4+SeCl5−: Raumgruppe Ima2, Z = 8, Strukturlösung mit 1757 beobachteten unabhängigen Reflexen, R = 0,029. Gitterkonstanten bei −50°C; a = 1651,6; b = 1201,2; c = 1166,4 pm. Die SeCl5− ‐Ionen sind über interionische SeCl … Se‐Kontakte entlang der kristallographischen c‐Achse zu Ketten assoziiert.

(PPh4+)2SeCl42− · 2CH3CN: Raumgruppe P21/n, Z = 2, Strukturlösung mit 2578 beobachteten unabhängigen Reflexen, R = 0,050. Gitterkonstanten bei −80°C: a = 1288,5; b = 726,0; c = 2585,8 pm; β = 101,65°. Die Verbindung enthält planar‐quadratische SeCl42−‐Ionen, die nahezu D4h‐Symmetrie erfüllen.
Darstellung und spektroskopische Charakterisierung der Monofluorohydro‐closo‐Borate [B6H5F]2− und [B12H11F]2−
Authors: Thomsen H. , Haeckel O. , Krause U. , Preetz W.
Published: December 2004

Bei der Umsetzung von [B6H6]2− mit 1‐(Chloromethyl)‐4‐fluoro‐1,4‐diazabicyclo[2.2.2]octan‐bis(tetrafluoroborat) in Acetonitril entsteht Monofluorohydro‐closo‐Hexaborat [B6H6F]− (1) in guten Ausbeuten. [B12H12]2− reagiert mit wasserfreiem HF zum entsprechenden Monofluorododecaborat [B12H11F]2− (2). Die Verbindungen werden durch Ionenaustauschchromatographie an Diethylaminoethyl(DEAE)‐Cellulose von Nebenprodukten getrennt. Die 11B‐NMR‐Spektren weisen die charakteristischen Signalmuster (1 : 4 : 1) für ein monosubstituiertes B6‐Oktaeder bzw. (1 : 5 : 5 : 1) für ein monosubstituiertes B12‐Ikosaeder mit starken Tieffeldshifts der ipso‐B‐Kerne bei +9,3 ppm für (1) und bei +9,0 ppm für (2) auf. Die in den 19F‐NMR‐Spektren bei −212 ppm für (1) und −209 ppm für (2) auftretenden Quartetts beweisen eine direkte BF‐Bindung. In den IR‐Spektren, für (1) auch im Raman‐Spektrum, werden vom F‐Substituenten abhängige Gerüstschwingungen bei 1195 (1) bzw. 1182 und 1154 cm−1 (2) und in den Raman‐Spektren die B6F‐Valenzschwingung bei 535 cm−1 sowie die B12F‐Valenzschwingung bei 445 cm−1 beobachtet.
Cadmium in tetragonal pyramidaler Koordination im Barium‐Cadmium‐Oxovanadat: Ba2Cd3(VO4)2(V2O7)
Authors: Mertens B. , Müller‐Buschbaum Hk.
Published: December 2004

Einkristalle von Ba2Cd3(VO4)2(V2O7) wurden durch Kristallisation aus einer Schmelze von BaCO3, CdO und V2O5 dargestellt. Sie zeigen orthorhombische Symmetrie, Raumgruppe DP212121 mit a = 7,206(2), b = 9,978(1), c = 19,617(3) Å, Z = 4. Die Kristallstruktur zeichnet sich durch VO4‐Tetraeder, V2O7‐Tetraederdoppel, CdO6‐Oktaeder, BaO12− und BaO9−Polyeder und für Cd unübliche tetragonale Pyramiden aus. Die beobachteten [CdO4]‐Zick‐zack‐Ketten werden durch VO4−Tetraeder, V2O7‐Tetraederdoppel und CdO5−Pyramiden unter Ausbildung einer längs [100] orientierten Tunnelstruktur vernetzt. Die Tunnel sind mit Ba2+ aufgefüllt.
Darstellung, Kristallstruktur, Schwingungsspektren und Normalkoordinatenanalyse von K2[OsCl5(CO)] · H2O
Authors: Bernhardt E. , Preetz W.
Published: December 2004

Die Röntgenstrukturanalyse von K2[OsCl5(CO)] · H2O (monoklin, Raumgruppe P21/c a = 13,600(2), b = 7,122(1), c = 22,186(11) Å, β = 98,66(3)°, Z = 8) hat gezeigt, daß zwei kristallographisch unabhängige aber sehr ähnliche Komplexanionen [OsCl5(CO)]2− mit annähernd C4v‐Punktsymmetrie vorliegen. Durch den größeren trans‐Einfluß der Carbonylgruppe sind die Bindungsabstände in der ClOsCO Achse OsCl = 2,449(2), 2,430(2) Å länger als in der Oktaederbasis: OsCl = 2,340‐2,370 Å. Das Kristallwasser ist an Kalium koordiniert (KOH2 = 2,625‐2,815 Å). Mit den röntgenographisch bestimmten Molekülparametern lassen sich die IR‐ und Raman‐Spektren durch Normalkoordinatenanalyse zuordnen. Die Valenzkraftkonstanten betragen fd(CO) = 15,30, fd(OsC) = 3,88, fd(OsCl) = 1,81, fd(OsCl) = 1,36, fd(OH) = 7,65, 7,82, 7,79 mdyn/Å. Die Festigung der OsC‐Bindung durch stärkere Rückbindung in dem OsIII(d5)‐Komplex im Vergleich zur isostrukturellen OsIV(d4)‐Verbindung wird diskutiert.
Reactions of Hexanuclear Niobium and Tantalum Halide Clusters with Mercury(II) Halides. I. Synthesis and structures of the semiconducting compounds [M6Br12(H2O)6][HgBr4] · 12H2O, MNb, Ta
Authors: Vojnović M. , Antolić S. , Kojić‐Prodić B. , Brničević N. , Miljak M. , Aviani I.
Published: December 2004

A method for the preparation of new solvated clusters of the composition [M6Br12(H2O)6][HgBr2X2] · 12H2O (MNb, Ta; XCl, Br, I) is given. The cubic crystals of [Nb6Br12(H2O)6][HgBr4] · 12H2O 1 and [Ta6Br12(H2O)6][HgBr4] · 12H2O 2 were characterized by the X‐ray structure analysis: 1: cubic, space group Fd3m, a = 21.0072(6) Å, Z = 8, R = 0.051 (Rw = 0.066); 2: cubic, space group Fd3m, a = 20.9698(1) Å, Z = 8, R = 0.038 (Rw = 0.050). 1 and 2 contain octahedral cluster cation [M6Br12(H2O)6]2+ and tetrahedrally arranged [HgBr4]2− anion. The MM bond distances are 2.949(1) Å for 1 and 2.9000(8) Å for 2. The HgBr bond distances in [HgBr4]2− anion are 2.614(2) Å in 1 and 2.622(2) Å in 2. The crystal packing patterns of the isostructural clusters 1 and 2 involve the three‐dimensional hydrogen bond network; the crystalline water molecules act as donors of hydrogen to the bromine atoms of the cluster and [HgBr4]2− units, whereas the coordinated water molecules form hydrogen bonds to the crystalline water molecules. [Nb6Br12(H2O)6][HgBr4] · 12H2O is diamagnetic and semiconducting with the activation energy, Ea = 0.20 eV.
Heterobimetallische phosphanido‐verbrückte Zweikern‐Komplexe ‐ Synthese von cis‐rac‐[(η‐C5H4R)2Zr{μ‐PH(2,4,6−iPr3C6H2)}2M(CO)4] (RMe, MCr, Mo; RH, MMo)
Authors: Senff Uwe , Kurz Stefan , Hey‐Hawkins Evamarie
Published: December 2004

Die Zirconocen‐Bisphosphanido‐Komplexe [(η‐C5H4R)2Zr{PH(2,4,6−iPr3C6H2)}2] (RMe, H) setzen sich mit [(NBD)M(CO)4] (NBDNorbornadien, MCr, Mo) zu den diastereomeren‐reinen phosphanido‐verbrückten heterobimetallischen Zweikern‐Komplexen cis‐rac‐[(η‐C5H4R)2Zr{μ‐PH(2,4,6‐iPr3C6H2)} 2M(CO)4] [RMe, MCr (1), Mo (2); RH, MMo (3)] um. Hingegen wird keine Reaktion von [(η‐C5H5)2Zr{PH(2,4,6‐t Bu3C6H2)}2] mit [Pt(PPh3)4] beobachtet. 1—3 wurden spektroskopisch charakterisiert. NMR‐spektroskopisch kann für 1—3 das Vorliegen des racemischen Isomers gezeigt werden. 3 reagiert bei Raumtemperatur nicht mit CS2, (NO)BF4, Me3NO und PH(2,4,6‐Me3C6H2)2. Mit Et2AlH und PhCCH wird Zersetzung beobachtet.
Sr3GdRhO6 ‐ The First RhIII Compound with the K4CdCl6 Structure‐type: Synthesis, Crystal Structure, and Magnetic Properties
Authors: Núñez Pedro , Rzeznik Maria A. , zur Loye Hans‐Conrad
Published: December 2004

The compound Sr3GdRhO6 has been synthesized and structurally characterized by Rietveld refinement of powder X‐ray diffraction data. (space group R3c; Z = 6; a = 9.7840(5) Å; c = 11.4196(7) Å) This compound is isostructural with K4CdCl6. The structure consists of infinite one‐dimensional chains of alternating face‐shared RhO6 octahedra and GdO6 trigonal prisms. The strontium cations are located in a distorted square antiprismatic environment. Magnetic susceptibility data show that Sr3GdRhO6 obeys the Curie law with ηeff = 7.80 B.M., consistent with an oxidation state of +3 for both rhodium and gadolinium.
Silylen‐Reaktionen mit Selenophen und einem Tellurophen: Bildung und Strukturen eines 1,3‐Diselena‐2,4‐disiletans und eines 1,3‐Ditellura‐2,4‐disiletans [1]
Authors: Weidenbruch Manfred , Kirmaier Lars , Kroke Edwin , Saak Wolfang
Published: December 2004

Photolytisch aus Hexa‐tert‐butylcyclotrisilan erzeugtes Di‐tert‐butylsilylen reagiert mit Selenophen oder 2,5‐Dimethyltellurophen unter Chalkogenabstraktion zum 1,3‐Diselena‐2,4‐disiletan 6 und 1,3‐Ditellura‐2,4‐disiletan 7. Die Röntgenstrukturanalysen von 6 und 7 zeigen das Vorliegen planarer Vierringe mit den kleineren endocyclischen Winkeln an den Chalkogen‐ und den größeren an den Siliciumatomen.
Ternäre Chloride in den Systemen NaCl/HoCl3 und NaCl/ErCl3
Authors: Seifert H. J. , Sandrock J.
Published: December 2004

Die Zustandsdiagramme der Systeme NaCl/HoCl3 und NaCl/ErCl3 wurden mittels DTA und Hochtemperatur‐Guinieraufnahmen untersucht. Es existieren Verbindungen Na3LnCl6 und NaLnCl4 (Ln  Ho, Er) sowie NaHo2Cl7. NaHoCl4 wandelt sich bei 374° vom NaGdCl4− in den NaErCl4‐Typ um. Mittels Lösungskalorimetrie und EMK‐Messungen in galvanischen Feststoffzellen wurden die thermodynamischen Funktionen der ternären Chloride bezüglich der Bildung aus NaCl und LnCl3 bestimmt. Die Verbindungen NaLnCl4 weisen die größte Stabilität auf.
Synthese und Eigenschaften von Eisen(II)‐Komplexen mit vier‐ und fünfzähnigen N,S‐Chelatliganden. Kristallstruktur von [Fe(GBMA)py] · py (GBMA2− = Glyoxal‐bis‐(2‐mercaptoanil))
Authors: Karsten P. , Maichle‐Mössmer C. , Strähle J.
Published: December 2004

Die Komplexe Glyoxal‐bis‐(2‐mercaptoanil)eisen(II), [Fe(GBMA)], Diacetyl‐bis‐(2‐mercaptoanil)eisen(II), [Fe(DBMA)] und o‐Phthaldialdehyd‐bis‐(2‐mercaptoanil)eisen(II), [Fe(PhBMA)] wurden durch direkte Umsetzung der entsprechenden protonierten Liganden mit wasserfreiem Eisen(II)‐acetat dargestellt. Die Synthese von Pyridin‐2,6‐dialdehyd‐bis‐(2‐mercaptoanil)eisen(II), [Fe(PyBMA)] erfolgte mit Hilfe einer Templatsynthese aus 2,6‐Pyridindialdehyd, 2‐Aminothiophenol und Eisen(II)‐acetat. Durch Umkristallisieren in Pyridin wurden aus [Fe(GBMA)] und [Fe(DBMA)] die Verbindungen [Fe(GBMA)py] · py und [Fe(DBMA)py] · py erhalten. Von allen Komplexen wurden die magnetischen Eigenschaften bestimmt und die Mössbauer‐Spektren bei 82 K registriert. [Fe(GBMA)] und [Fe(DBMA)] zeigen im Cyclovoltammogramm quasireversibles Redoxverhalten, während bei [Fe(PhBMA)] eine irreversible Oxidation beobachtet wird. [Fe(GBMA)py] · py kristallisiert monoklin in der Raumgruppe P21 mit a = 1288,7(1), b = 1242,63(5), c = 1396,0(1) pm, β = 98,24(1)° und Z = 4. Im Neutralkomplex ist das Fe‐Atom quadratisch‐pyramidal mit dem Pyridin‐Stickstoffatom in apikaler Position koordiniert. Die Pyramidenbasis wird von den zwei Stickstoff‐ und Schwefelatomen des Liganden GBMA2− aufgespannt. Das Fe‐Atom befindet sich 40 pm oberhalb der Pyramidenbasis. Die Abstände zu den Donoratomen des GBMA‐Liganden betragen im Mittel FeN = 190 pm und FeS = 222 pm. Der FeN‐Abstand zum Pyridinstickstoffatom liegt bei 207 pm.
Synthese und spektroskopische Charakterisierung einiger Pentacarbonylwolfram(0)‐Komplexe mit verschiedenen 1H‐Phosphiren‐Liganden, Kristallstrukturen von , und
Authors: Ostrowski Annette , Jeske Jörg , Ruthe Frank , Jones Peter G. , Streubel Rainer
Published: December 2004

Der Wolfram(0)‐Komplex 1 reagiert beim Erwärmen mit den Acetylenderivaten 2a–f in Toluol zu Benzonitril und den Komplexen 4a–f (4a: R1  Ph, R2  H; 4b: R1  Ph, R2  CH3; 4c: R1  OEt, R2  H; 4d: R1  Ph, R2  CO2Et; 4e: R1, R2  CO2Me; 4f: R1, R2  SiMe3), die chromatographisch gereinigt und isoliert wurden. Spektroskopische und massenspektrometrische Daten der Komplexe 4a‐f werden angegeben und diskutiert. Die Strukturen der Komplexe 4a, b und d konnten durch Einkristall‐Röntgenstrukturanalyse aufgeklärt werden (4a: Raumgruppe P21/n, Z = 4, a = 937,5(2) pm, b = 2202,4(6) pm, c = 1266,3(4) pm, β = 108,94(4)°; 4b: Raumgruppe P21/c, Z = 4, a = 1293,9(2) pm, b = 923,5(1) pm, c = 2223,4(3) pm, β = 92,385(6)°; 4d: Raumgruppe P21/c, Z = 4, a = 955,2(2) pm, b = 3190,9(4) pm, c = 930,7(2) pm, β = 99,64(1)°).
Metallkomplexe mit biologisch wichtigen Liganden. XCV. η5‐ Pentamethylcyclopentadienyl‐Rhodium‐, ‐Iridium‐, (η6‐Benzol)‐Ruthenium‐ und Phosphan‐Palladium‐Komplexe von Prolinmethylester und Prolinamid
Authors: Hoffmüller Winfried , Polborn Kurt , Knizek Jörg , Nöth Heinrich , Beck Wolfgang
Published: December 2004

Prolinmethylester (L1) und Prolinamid (L2) bilden mit den chlorverbrückten Komplexen [(η5‐C5Me5)MCl2]2 (M  Rh, Ir), [(η6‐p‐Cymol)RuCl2]2 und [Et3PPdCl2]2 Verbindungen mit N‐ und N,O‐Koordination: (η5‐C5Me5)M(Cl2)L1 (1, 2 M  Rh, Ir), [(η5‐C5Me5) Rh(Cl) (L2)]+Cl− (5), [(η6‐ C6Me6)Ru(Cl) (L2)]+Cl− (6), [(η6‐p‐ Cymol)Ru(Cl)(L2)]+Cl− (7), [(η5‐ C5Me5)M(Cl)(L2‐H+)] (9, 10 M  Rh, Ir), (Et3P)Pd(Cl)2L1 (3) und [(Et3P)Pd(Cl)(L2)]+Cl− (8). Die NMR Spektren weisen darauf hin, daß von 5 und 6 jeweils nur ein Diastereoisomeres entsteht. Die Komplexe 1, 2, 3 und 5 wurden durch Röntgenstrukturanalyse charakterisiert.
Training in consultation
Authors: Meyers Joel
Published: December 2004

Conclusions

This paper has pointed out some important goals, techniques, and dilemmas associated with consultation training and it has reviewed some of the relevant literature. A variety of ideas have been presented that should be useful to the trainer devising a workshop, a course, or a series of programmatic training experiences. In addition to describing key goals for training, the training techniques included readings, writing projects, and other didactic exercises, as well as modeling, role‐playing with feedback, andin vivo practice with feedback. However, it should be noted that one important issue that has been ignored in the literature on consultation training is theconsultee (Meyers, Note 2). Effective consultation would be more likely if consultees receiving training regarding the knowledge base of consultation and the skills necessary to be an effective consultee.
Seafloor geomorphology of convergent margins: Implications for Cascadia seismic hazard
Authors: McAdoo Brian G. , Capone Mark K. , Minder Justin
Published: December 2004

We compare the geomorphology of several convergent continental margins to constrain the seismic hazard of the Cascadia margin offshore Oregon, and present the possibility of a slow earthquake mechanism for a characteristic Cascadia event. The Cascadia seafloor has a very delicate bathymetry, with well‐preserved landslides and noneroded slopes approaching 20°, unusual for a margin that produces M∼9 earthquakes. Three‐dimensional seismic and multibeam bathymetry data from the Nankai Trough suggest ubiquitous erosion over the entire margin with a smooth lower slope, devoid of large landslides, as would be expected on an accretionary margin that produces M∼8.5 earthquakes. The accretionary Makran (Pakistan) and Kodiak (Alaska) margins have evidence of mass wasting and smooth lower slopes that lack large landslides. The nonaccreting Nicaraguan, Sanriku, and Aleutian margins have large, well‐preserved landslides that add roughness elements to the slope, and have produced anomalously large tsunami, suggesting a slow source mechanism. Quantitative analysis of the lower slope roughness suggests the Cascadia has a characteristic geomorphology substantially different than the other sedimented convergent margins. The geomorphology, heat flow, pore pressure regime, and accounts of the 1700 “megathrust” event suggest a possible characteristic earthquake with a slow source mechanism. Rupture velocity would be high enough to be tsunamigenic, but accelerations would be low such that downslope erosion is minimal. To make the distinction between a slow and rapid source mechanism is critical in planning for seismic hazard in the Pacific Northwest.
Can finite‐frequency effects be accounted for in ray theory surface wave tomography?
Authors: Sieminski Anne , Lévêque Jean‐Jacques , Debayle Eric
Published: December 2004

We present a series of synthetic tests showing that regional surface wave tomographies with a dense path coverage of the target region can be safely conducted under ray theory because the shortcomings of ray theory in considering finite‐frequency effects can be counterbalanced by a physically‐based regularization of the inversion. In particular, we show that with ray theory applied under the above conditions, it is possible to detect heterogeneities with length scales smaller than the wavelength of the data set.
The use of mutually exclusive categories for atopic sensitization: A contrasting effect for family size on house dust mite sensitization compared with ryegrass sensitization
Authors: Ponsonby Anne‐Louise , Dwyer Terence , Kemp Andrew , Lim Lynette , Cochrane Jennifer , Carmichael Allan
Published: December 2004

Our aim was to examine the relative importance of family size on sensitization to two different allergens: ryegrass and house dust mite (HDM), using a mutually exclusive classification for allergen‐specific sensitization. An 8‐year follow‐up birth cohort study of children born between 1988–89 was conducted. The follow‐up sample consisted of 498 children residing in Northern Tasmania in 1997 (84% of eligible). Outcome measures included skin prick test (SPT) reaction to nine aeroallergens and parental questionnaire. Family size was defined as sibling number in 1997. Children with a positive SPT to either Der p or Der f house dust mite but not ryegrass were classified as HDM‐exclusive (n = 84). Children with a positive SPT to ryegrass but not HDM were classified as ryegrass‐exclusive (n = 43). Family size was associated with reduced ryegrass‐exclusive sensitization [AOR 0.57 (0.39, 0.84) per increase in sibling number] but not HDM‐exclusive sensitization [AOR 0.97 (0.77,1.23)]. The difference in the family size effect on these sensitization outcomes was significant (p = 0.02). Similarly, family size tended to be associated with reduced asthma among ryegrass‐exclusive sensitized children [AOR 0.45 (0.18,1.12)] but not HDM‐exclusive sensitized children [(AOR 1.46(0.80–2.65)]. Large family size was strongly associated with reduced sensitization for ryegrass allergens but not HDM allergens using mutually exclusive sensitization categories. If this difference is confirmed in other studies, the contrasting effect of family size may reflect differences between these allergens with regard to level or timing of early life exposure, differences in allergen ‐specific potentiation for sensitization or unidentified confounding. The use of mutually exclusive categories for allergen sensitization will assist future work on child atopic disease.
Flow dependency and off‐line measurement of exhaled NO in children
Authors: Van Amsterdam J. G. C. , Zanen P. , Somer S. , Van Loveren H. , Opperhuizen A. , Steerenberg P. A.
Published: December 2004

Levels of exhaled nitric oxide (eNO) are flow‐dependent, and the choice of an optimal flow rate for off‐line and on‐line eNO measurement has raised much debate. Recently, a flow rate of 50 ml/s was recommended, but children younger than 5–6 years are not capable of stabilizing their expiratory flow at low flow rates. The power of off‐line eNO values to discriminate between normal and atopic children was therefore evaluated at different exhalation flow rates. At flow rates of both 8.3 ml/s and of 350 ml/s, children (8–12 years) sensitive to house dust mite have two‐fold higher eNO values (p < 0.001) as compared with children lacking such a sensitivity. The power of eNO to discriminate between normal and atopic subjects was similar at the two flow rates (no difference in AUC of receiver operation curves, p = 0.89). All children from 4.5 to 5 years of age (n = 29) could perform a single off‐line exhalation manoeuvre at high (>350 ml/s) but not at low (8.3 ml/s) flow rates. At high exhalation flow rate, eNO was 7.1 ± 2.4 (mean ± SD) median, 6.5 p.p.b. with a mean variation coefficient of 5.5%. Depending on their developmental level, about half of the younger children (35–46 months of age) could perform an off‐line exhalation manoeuvre at high flow rate with good reproducibility (mean variation coefficient of 6.6%). It is concluded that an exhalation flow rate of 350 ml/s is feasible to determine off‐line eNO‐values in children from 3.5 years of age, and that this high flow rate does not compromise the power of eNO to detect allergic disease.
Comparison of cytokinin‐binding proteins from wheat and oat grains
Authors: Kamínek Miroslav , Trčková Marie , Fox J. Eugene , Gaudinová Alena
Published: December 2004

Cytokinin‐binding proteins (CBPs) isolated from mature grains of oat (Avena sativa L.) and wheat (Triticum aestivum L.) by acid precipitation, ion‐exchange and affinity chromatography had similar characteristics, although they differed somewhat in apparent molecular weight of the native protein as determined by gel filtration (109 and 133 kDa, respectively) and subunit size as estimated by SDS‐polyacrylamide gel electrophoresis (47 and 55 kDa, respectively). Highly purified oat CBP showed very weak but distinct immunochemical cross‐reactivity with anti‐wheat CBP IgG, indicating different immunogenic properties of the two CBPs. Nevertheless, both CBPs exhibited very similar binding of different cytokinins and were characterized by high affinity for N6‐benzyladenine (BA)‐type and by low affinity for zeatin‐type cytokinins to both wheat and oat CBPs and by somewhat higher binding activities of oat CBP compared to wheat CBP (Kds for BA: 4.6 × 10−7 M and 6.8 × 10−7 M, respectively). The potential role of CBPs in regulating free BA‐type cytokinin levels during cereal grain development and germination is discussed.
New cytokinin metabolites in IPT transgenic Arabidopsis thaliana plants
Authors: Werner Tomáš , Hanuš Jan , Holub Jan , Schmülling Thomas , Van Onckelen Harry , Strnad Miroslav
Published: December 2004

Two novel cytokinin metabolites were identified in transgenic Arabidopsis thaliana (L.) Heynh. plants containing the bacterial IPT gene under the transcriptional control of a heat‐regulated promoter. After cyclic heat‐shock treatment, the endogenous cytokinin concentrations were elevated up to 100‐fold compared to the wild‐type plants. More then 20 different cytokinin metabolites were found, with zeatin‐type cytokinins being the most abundant. The metabolic inactivation of these compounds occurred predominantly through N‐glucosylation. No significant accumulation of isopentenyladenine‐type cytokinins, and only a small increase in dihydrozeatin metabolites, was observed. Subsequent studies of the abundant, unidentified conjugates revealed the presence of zeatin and dihydrozeatin diglucoside conjugates. Structural analysis, utilizing electrospray‐liquid tandem mass spectrometry, identified these as a zeatin‐O‐glucoside‐9‐glucoside and dihydrozeatin‐O‐glucoside‐9‐glucoside, respectively. A third unknown metabolite, was tentatively identified as a phosphorylated form of zeatin‐9‐glucoside. The biological activity of these compounds in three cytokinin bioassays was low. A comparison of the cytokinin pattern in transgenic and wild‐type plants indicates that these specific metabolites accumulate as a consequence of enhanced cytokinin biosynthesis, and are probably involved in the homeostatic mechanisms that control endogenous cytokinin levels.
Molecular events following perception of ultraviolet‐B radiation by plants
Authors: Brosché Mikael , Strid Åke
Published: December 2004

Exposure of plants to UV‐B radiation (280–320 nm) results in changes in expression of a large number of genes. Before UV‐B radiation or light of other wavelengths can give rise to a cellular response, it has to be perceived by some kind of receptor, and the information transduced via a signalling pathway to the target molecules, be it proteins in the cytoplasm or the genetic material in the nucleus. The perception of low levels of UV‐B probably occurs via a UV‐B photoreceptor followed by several different signalling pathways. These pathways include second messengers such as calcium, kinases and the catalytic formation of reactive oxygen species. High levels of UV‐B, on the other hand, probably cause cellular damage and oxidative stress, thus activating a general stress signal transduction pathway which leads to a response similar to that which occurs after pathogen attack and other stresses. Some of the genes identified so far as being regulated by UV‐B encode proteins involved in the biosynthesis of protective pigments, DNA repair and antioxidative enzymes, photosynthetic genes, cell cycle genes, and stress genes induced by other types of stimuli (i.e. pathogenesis‐related proteins and senescence‐induced genes). In the light of the information obtained on components necessary for UV‐B‐induced changes in gene expression, we propose in this mini‐review a working model for UV‐B perception and signal transduction. This model also takes into account dosage differences for the observations, which imply a separation into UV‐B‐specific and more general stress signal transduction.
Transgenically enhanced sorbitol synthesis facilitates phloem‐boron mobility in rice
Authors: Bellaloui Nacer , Yadavc Ram C. , Chern Maw‐Sheng , Hu Hening , Gillen Anne M. , Greve Carl , Dandekar Abhaya M. , Ronald Pamela C. , Brown Patrick H.
Published: December 2004

The tolerance of crops to a shortage of boron (B) in the soil varies markedly among species. This variation in tolerance is due, in part, to a species ability to form phloem mobile B‐sugar‐alcohol complexes (such as B‐mannitol or B‐sorbitol) which enhance the remobilization of B within the plant. Species lacking the capacity to form B‐sugar alcohol complexes are intolerant of even short‐term deficits in soil B supply. Here we have genetically engineered rice (Oryza sativa L.) cultivar Taipei 309 (TP309) with the sorbitol‐6‐phosphate dehydrogenase (S6PDH) gene, a key enzyme for sorbitol production, and determined the effect of this transformation on the physiology of B remobilization. Sorbitol was detected in the S6PDH transgenic plants as well as in vector‐transformed plants and wild‐type (TP 309) plants, although the concentration of sorbitol in the S6PDH transgenic plants was significantly enhanced. Remobilization of B from mature leaves to flag leaves correlated with increased levels of sorbitol. The presence of sorbitol and detection of B remobilization in the wild‐type and vector‐transformed plants suggests that rice utilizes an unknown pathway for sorbitol synthesis and may partly explain the relative insensitivity of rice to B deficits when compared to other graminaceous crops.
Transport and metabolism of xylem cytokinins during lateral bud release in decapitated chickpea (Cicer arietinum) seedlings
Authors: Mader Johanna C. , Turnbull Colin G N. , Emery R. J. Neil
Published: December 2004

Although cytokinins (CKs) are widely thought to have a role in promoting shoot branching, there is little data supporting a causative or even a correlative relationship between endogenous CKs and timing of bud outgrowth. We previously showed that lateral bud CK content increased rapidly following shoot decapitation. However, it is not known whether roots are the source of this CK. Here, we have used shoot decapitation to instantaneously induce lateral bud release in chickpea seedlings. This treatment rapidly alters rate and direction of solvent and solute (including CK) trafficking, which may be a passive signalling mechanism central to initiation of lateral bud release. To evaluate changes in xylem transport, intact and decapitated plants were infiltrated with [3H]zeatin riboside ([3H]ZR), a water‐soluble blue dye or [3H]H2O by injection into the hypocotyl. All three tracers were recovered in virtually all parts of the shoot within 1 h of injection. In intact plants, solute accumulation in the lateral bud at node 1 was significantly less than in the adjacent stipule and nodal tissue. In decapitated plants, accumulation of [3H]ZR and of blue dye in the same bud position was increased 3‐ to 10‐fold relative to intact plants, whereas content of [3H]H2O was greatly reduced indicating an increased solvent throughput. The stipule and cut stem, predicted to have high evapotranspiration rates, also showed increased solute content accompanied by enhanced depletion of [3H]H2O. To assess whether metabolism modifies quantities of active CK reaching the buds, we followed the metabolic fate of [3H]ZR injected at physiological concentrations. Within 1 h, 80–95% of [3H]ZR was converted to other active CKs (mainly zeatin riboside‐5′phosphate (ZRMP) and zeatin (Z)), other significant, but unconfirmed metabolites some of which may be active (O‐acetylZR, O‐acetylZRMP and a compound correlated with sites of high CK‐concentrations) and inactive catabolites (adenosine, adenine, 5′AMP and water). Despite rapid metabolic degradation, the total active label, which was indicative of CK concentration in buds, increased rapidly following decapitation. It can be inferred that xylem sap CKs represent one source of active CKs appearing in lateral buds after shoot decapitation.
Effects of nutrient availability on biomass allocation as well as constitutive and rapid induced herbivore resistance in poplar
Authors: Glynn Carolyn , Herms Daniel A. , Egawa Marie , Hansen Robert , Mattson William J.
Published: December 2004

Many studies have examined effects of nutrient availability on constitutive herbivore resistance of plants, but few have addressed effects on expression of rapid induced resistance (RIR). We quantified effects of two levels of nutrient availability on growth, biomass allocation, photosynthesis, and constitutive secondary metabolism of black poplar (Populus nigra). We also examined effects of nutrient availability on expression of constitutive resistance of poplar to gypsy moth (Lymantria dispar) and whitemarked tussock moth (Orgyia leucostigma), as well as RIR to both folivores in response to localized herbivory by gypsy moth.

The high nutrient treatment had no effect on photosynthetic rate of poplar, but dramatically increased relative growth rate, total biomass, and total leaf area, while foliar phenolic concentrations and root:shoot ratio decreased. Plant growth was negatively correlated with foliar phenolic concentrations, which is consistent with predictions of the Growth/Differentiation Balance Hypothesis when increased nutrient availability increases growth without affecting photosynthesis. These responses of root:shoot ratio and constitutive secondary metabolism to nutrient availability are consistent with those proposed by models of adaptive phenotypic plasticity in resource allocation patterns.

Nutrient availability affected constitutive resistance of poplar to first and fifth instar gypsy moth larvae, which grew much faster on high fertility plants. However, nutrient availability had no effect on constitutive resistance to whitemarked tussock moth. Localized herbivory elicited systemic RIR in poplar within 72 hours. However, the magnitude of RIR was dependent on nutrient availability, with differing effects on the two insect species. Expression of RIR to gypsy moth was most dramatic in the high fertility treatment. In contrast, RIR to whitemarked tussock moth was expressed only in the low fertility treatment. The idiosyncratic nature of effects of nutrient availability on constitutive and induced resistance challenges the value of using insect bioassays as surrogate measures of secondary metabolism for testing allocation models of plant defense, as well as the value of generalized plant defense models for predicting effects of environmental variation on resistance to specific herbivores. These results also suggest that the effects of nutrient availability on the expression of RIR may represent a largely over‐looked source of variation in plant/herbivore interactions.
Control of plant species diversity and community invasibility by species immigration: seed richness versus seed density
Authors: Brown Rebecca L. , Fridley Jason D.
Published: December 2004

Immigration rates of species into communities are widely understood to influence community diversity, which in turn is widely expected to influence the susceptibility of ecosystems to species invasion. For a given community, however, immigration processes may impact diversity by means of two separable components: the number of species represented in seed inputs and the density of seed per species. The independent effects of these components on plant species diversity and consequent rates of invasion are poorly understood. We constructed experimental plant communities through repeated seed additions to independently measure the effects of seed richness and seed density on the trajectory of species diversity during the development of annual plant communities. Because we sowed species not found in the immediate study area, we were able to assess the invasibility of the resulting communities by recording the rate of establishment of species from adjacent vegetation. Early in community development when species only weakly interacted, seed richness had a strong effect on community diversity whereas seed density had little effect. After the plants became established, the effect of seed richness on measured diversity strongly depended on seed density, and disappeared at the highest level of seed density. The ability of surrounding vegetation to invade the experimental communities was decreased by seed density but not by seed richness, primarily because the individual effects of a few sown species could explain the observed invasion rates. These results suggest that seed density is just as important as seed richness in the control of species diversity, and perhaps a more important determinant of community invasibility than seed richness in dynamic plant assemblages.
Oestrogenic Steroids and Melanoma Cell Interaction with Adjacent Skin Cells Influence Invasion of Melanoma Cells In Vitro
Authors: MAC NEIL SHEILA , EVES PAULA , RICHARDSON BEN , MOLIFE RHODA , LORIGAN PAUL , WAGNER MARK , LAYTON CHRIS , MORANDINI RENATO , GHANEM GHANEM
Published: December 2004

The invasion of melanoma is complex and multi‐staged and involves changes in both cell/extracellular matrix (ECM) and cell/cell interactions. Female steroids and α‐MSH have also been reported to influence metastatic melanoma progression, but their mechanisms of action are unknown. Accordingly, our aim was to establish in vitro models to examine (a) the influence of sex steroids and α‐melanocyte‐stimulating hormone (α‐MSH) on tumour invasion and the influence of (b) ECM proteins and (c) adjacent cells on melanoma invasion.

In the first model, melanoma cell invasion through fibronectin over 20 hr under serum‐free conditions was used to investigate the effects of 17β‐oestradiol and oestrone on the invasion of human melanoma cell lines, A375‐SM and HBL. A375‐SM, but not HBL cells, proved very susceptible to inhibition by female steroids. However, invasion of the HBL line was inhibited by α‐MSH. Using the second model of reconstructed human skin based on de‐epidermised acellular dermis, we found that the HBL cells on their own failed to invade into the dermis (irrespective of the presence or absence of the basement membrane). However, there was a significant synergistic interaction between keratinocytes, fibroblasts and HBL cells, such that a modest invasion of HBLs into the dermis was seen within 2 weeks when other skin cells were present. In contrast, A375‐SM cells showed a significant ability to invade the dermis in the absence of other cells, with less invasion when other skin cells were present.

In summary, these models have provided new information on the extent to which melanoma cell invasion is sensitive to oestrogenic steroids and to α‐MSH and to interaction, not only with adjacent skin cells but also to the presence of basement membrane antigens.
Evolution and Development of Pigment Cells: At the Crossroads of the Discipline
Authors: MASON KENNETH A. , FROST MASON SALLY K.
Published: December 2004

The following is a summary of the current state of comparative biology with respect to pigmentation. Recent results from molecular analyses of genes involved in pigmentation in lower vertebrates are compared with similar data from mouse and man. Particular emphasis has been placed on evolutionary and developmental aspects of pigmentation. Recent advances in molecular biology of lower vertebrate pigmentation allow for the comparison of orthologous molecules across a wider range of species than ever before; some of these results are summarized and used to highlight the current state of pigmentation from a comparative perspective. A more cellular, organismal approach is also explored to highlight some important lessons from comparative biology. Lastly, large‐scale evolutionary questions are put into a framework that highlights both the differences and similarities between mammals/birds and other vertebrates. It is the opinion of the authors that important, long‐standing questions in these areas can now be addressed in ways that have not been possible before. Thus, the discipline is at an exciting crossroads where developmental and evolutionary data can be used to create a unified view of pigment cells and pigments across many species.
The Melanocortin‐1 Receptor is a Key Regulator of Human Cutaneous Pigmentation
Authors: ABDEL‐MALEK ZALFA , SCOTT M. CATHY , SUZUKI ITARU , TADA AKIHIRO , IM SUNGBIN , LAMOREUX LYNN , ITO SHOSUKE , BARSH GREG , HEARING VINCENT J.
Published: December 2004

The cloning and characterization of the human melanocortin‐1 receptor (MC1R) and the demonstration that normal human melanocytes respond to the melanocortins, α‐melanocyte stimulating hormone (α‐MSH) and adrenocorticotrophic hormone (ACTH), with increased proliferation and eumelanogenesis had put an end to a long‐standing controversy about the role of melanocortins in regulating human cutaneous pigmentation. We have shown that α‐MSH and ACTH bind the human MC1R with equal affinity, and are equipotent in their mitogenic and melanogenic effects on human melanocytes. We also showed that the activation of the MC1R is important for the melanogenic response of human melanocytes to ultraviolet radiation (UVR). The MC1R is also the principal mediator of the inhibitory effects of agouti signaling protein (ASP) on melanogenesis. Expression of the MC1R is subject to regulation by its own ligands α‐MSH and ACTH, as well as by UVR and endothelin‐1. Recent studies that we conducted on the expression of MC1R variants by human melanocytes and the implications of these variants on the function of the MC1R revealed the following. Human melanocytes homozygous for Arg160Trp mutation in the MC1R demonstrated a significantly reduced response to α‐MSH. Also, this culture responded poorly to ASP and exhibited an exaggerated cytotoxic response to UVR. Another culture, which was homozygous for Val92Met mutation in the MC1R, demonstrated a normal response to α‐MSH. Heterozygous mutations that are frequently expressed in various melanocyte cultures did not disrupt MC1R function. These results begin to elucidate the significance of MC1R variants in the function of the receptor. Our data emphasize the significance of a normally functioning MC1R in the response of melanocytes to melanocortins, ASP, and UVR.
Hypertension Due to Blockade of Adenosine Receptors*
Authors: Guimarães Serafim , Morato Manuela , Sousa Teresa , Albino‐Teixeira António
Published: December 2004

Abstract: Chronic treatment of rats with 90 μg/kg/day DPSPX (1,3‐dipropyl‐8‐sulphophenylxanthine) during seven days leads to a hypertensive state which is characterized by marked morphological changes of the blood vessel walls as well as by important functional alterations. While the angiotensin‐converting enzyme (ACE) inhibitor captopril and the antagonist of angiotensin II AT 1 receptors losartan prevent the development of both hypertension and morphological changes, the selective β1‐adrenoceptor antagonist atenolol could prevent only the increase in blood pressure. It is concluded that at least two factors are involved in the development of the hypertensive state.
Diurnal and seasonal variations of the UV cut‐off wavelength and most erythemally effective wavelength of solar spectra
Authors: Kollias N. , Baqer A. H. , Ou‐Yang H.
Published: December 2004

Background Biologically effective solar ultraviolet radiation is defined as the product of the intensity of the solar spectrum and the erythema action spectrum at each wavelength. In this way we may arrive at the weighted effectiveness of each wavelength of solar radiation to produce a sunburn reaction. There have been many measurements of the variation of the solar spectrum with the time of the day and the time of the year, but questions remain as to the variation of the quality of the spectrum and the contribution of the shortest wavelengths of solar terrestrial radiation. The purpose of the present study was to determine the variation of the biologically effective solar spectrum with the time of the day and the time of the year and to determine the variation of the shortest wavelength that contributes to the sunburn reaction with the time of the day and the time of the year.

Methods Spectroradiometric measurements were made at ground level over the period of one year (1988–1989) and at different times of the day at latitude 29.5° north. The measured spectral irradiance was multiplied wavelength by wavelength by the erythema action spectra.

Results We determined that the biologically effective solar spectrum remains essentially the same over the times of the day that sunburn may be experienced. The maximally effective wavelength of biologically effective solar radiation was determined to be 308 nm. The cut‐off wavelength for biologically effective solar radiation (defined as the wavelength at which the biologically effective solar radiation is at 1% of its maximum) varied from 291 to 295 nm over the time of the year and from 292 to 296 nm over the day.

Conclusion For all practical purposes the biologically effective spectrum of solar ultraviolet radiation may be considered to remain constant over the period when sunburn may occur and the minimal wavelength of sunlight that contributes to sunburn is in the range of 291–296 nm.