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Thin 33S samples for the study of the 33S(n, α)30Si cross-section at the n_TOF facility at CERN were made by thermal evaporation of 33S powder onto a dedicated substrate made of kapton covered with thin layers of copper, chromium and titanium. This method has provided for the first time bare sulfur samples a few centimeters in diameter. The samples have shown an excellent adherence with no mass loss after few years and no sublimation in vacuum at room temperature. The determination of the mass thickness of 33S has been performed by means of Rutherford backscattering spectrometry. The samples have been successfully tested under neutron irradiation.

One of the most puzzling problems in Nuclear Astrophysics is the “Cosmological Lithium Problem”, i.e the discrepancy between the primordial abundance of \(^{7}\)Li observed in metal poor halo stars (Asplund et al. in Astrophys J 644:229–259, 2006, [1]), and the one predicted by Big Bang Nucleosynthesis (BBN). One of the reactions that could have an impact on the problem is \(^{7}\)Be(n,p)\(^{7}\)Li. Despite of the importance of this reaction in BBN, the cross-section has never been directly measured at the energies of interest for BBN. Taking advantage of the innovative features of the second experimental area at the n\(\_\)TOF facility at CERN (Sabate-Gilarte et al. in Eur Phys J A 53:210, 2017, [2]; Weiss et al. in NIMA 799:90, 2015, [3]), an accurate measurement of \(^{7}\)Be(n,p) cross section has been recently performed at n\(\_\)TOF, with a pure \(^{7}\)Be target produced by implantation of a \(^{7}\)Be beam at ISOLDE. The mesurement started in April 2016 and lasted for two months. The experimental procedure, the setup used in the measurement and the results obtained so far will be here presented.

Type 2 diabetes is characterised by impaired glucose-stimulated insulin secretion (GSIS) from pancreatic islets. Since erythropoietin-producing hepatoma (Eph)-ephrin bidirectional signalling fine-tunes GSIS from pancreatic beta cells, we investigated Eph receptor tyrosine kinases (RTK) as potential drug targets for selectively increasing GSIS.Insulin secretion assays were carried out using mouse and human pancreatic islets as well as mouse insulinoma (MIN6) cells in the presence or absence of two Eph RTK inhibitors. Furthermore, the most potent inhibitor was injected into mice to evaluate its effects on glucose tolerance and plasma insulin levels.We showed that the Eph RTK inhibitors selectively increased GSIS from MIN6 cells as well as mouse and human islets. Our results also showed that the insulin secretory effects of these compounds required Eph-ephrin signalling. Finally, pharmacological inhibition of Eph receptor signalling improved glucose tolerance in mice.We showed for the first time that Eph RTKs represent targets for small molecules to selectively increase GSIS and improve glucose tolerance.

The aim of this study was to investigate the effect of an organic cannabis extract on β-cell secretory function in an in vivo diet-induced obese rat model and determine the associated molecular changes within pancreatic tissue. Diet-induced obese Wistar rats and rats fed on standard pellets were subcutaneously injected with an organic cannabis extract or the vehicle over a 28-day period. The effect of diet and treatment was evaluated using the intraperitoneal glucose tolerance tests (IPGTTs) and qPCR analysis on rat pancreata harvested upon termination of the experiment. The cafeteria diet induced an average weight difference of 32g and an overall increase in body weight in the experimental groups occurred at a significantly slower rate than the control groups, irrespective of diet. Area under the curve for glucose (AUC(g)) in the obese group was significantly lower compared to the lean group (p

Objective Tissue-engineered blood vessels (TEBVs) represent an innovative approach for overcoming reconstructive problems associated with extended vascular diseases by providing small-calibre vascular grafts. This study aimed to evaluate a novel biomaterial of bacterially synthesised cellulose (BC) as a potential scaffold for TEBV. Methods Highly crystalline cellulose was produced by a bacterium ( Acetobacter xylinum ) using glucose as a source of carbon. Using a patented process, hollow-shaped segments of BC were created with a length of 10mm, an inner diameter of 3.0–3.7mm and a wall thickness of 0.6–1.0mm. These grafts were used to replace the carotid arteries of eight pigs, and after a follow-up period of 3 months, the grafts were removed and analysed, both macro- and microscopically. Results Seven grafts (87.5%) remained patent, whereas one graft was found to be occluded. Scanning electron microscopic examination revealed rapid re-cellularisation by recipient endothelial cells. Light microscopic examination showed a three-layered wall structure of the BC segments, with cellulose still being present in the media. Conclusion These data indicate that the innovative BC-engineering technique results in the production of stable vascular conduits, which exhibit attractive properties for their use in future TEBV programmes for vascular surgery.

The fluoride complexation of the group-4 elements Zr, Hf and Rf, and of the pseudo-homolog Th, has been investigated in mixed HNO3/HF solutions by studying Kd values on both cation exchange resins (CIX) and anion exchange resins (AIX) using the automated rapid chemistry apparatus ARCA. On the CIX, the four elements are strongly retained as cations below 10-3M HF. For Zr and Hf, the decrease of the Kd values due to the formation of fluoride complexes occurs between 10-3M HF and 10-2M HF. For Rf and Th, this decrease is observed at one order of magnitude higher HF concentrations. On the AIX, for Zr and Hf, a rise of the Kd values due to the formation of anionic fluoride complexes is observed between 10-3M HF and 10-2M HF, i.e. in the same range of HF concentrations where the decrease of the Kd values on the CIX is observed, yielding a consistent picture. For Rf and Th, on the AIX, no rise of the Kd values is observed even if the HF concentration is increased up to 1 M. By varying the concentration of the counter ion NO3-which is competing for the binding sites on the AIX resin, it could be shown, nevertheless, that Rf does form anionic fluoride complexes. Apparently, there is a more specific competition of NO3-with respect to [RfFx](x-4)-than with [ZrFy](y-4)-and [HfFz](z-4)-.

The sorption was studied of element 104 (rutherfordium, Rf) and thorium on the strongly acidic cation exchanger DOWEX 50×8. The experiments were carried out on-line. Rf is strongly retained on cation exchange resins from diluted HCl/HF solutions in a concentration range of 0.05 to 0.1 M HCl and HF concentrations up to 0.01 M. This behaviour is similar to its pseudohomologue thorium and very different from its lighter homologue hafnium which is desorbed from DOWEX 50×8 at HF concentrations above 10 −3 M. The tested ion exchange system is suitable for fast on-line separation of element 106 (seaborgium, Sg) from all other contaminations and its decay product Rf. It, therefore, allows the indirect identification of Sg.

In the II-VI compound ZnTe perturbed angular correlation and tracer diffusion experiments with the nuclear probe 100 Pd/ 100 Rh revealed the formation of a defect complex by the observation of a well-defined quadrupole interaction in tellurium-rich crystals. The defect complex is tentatively interpreted as a Pd A-centre with Pd on the chalcogen lattice site. Using the DLTS method no deep levels correlated to implanted palladium could be detected in the range of 0.2 to 0.8 eV above the valence band edge.

The sorption behavior of microamounts of Hf and Ta on DOWEX 50×8 and DOWEX 1×8 from aqueous HCl/HF solutions has been investigated. Suitable separation conditions for these two elements on cation exchange resins were found in solutions containing 1.5M HCl/10−4M HF and 0.05M HCl/10−3M HF. Kinetic experiments showed that the system can be applied in high speed on-line separations.

Perturbed angular distribution experiments on19F implanted into fullerites revealed a large fraction of fluorine atoms which are not subject to static quadrupole interactions in contrast to other allotropic forms of carbon.

A Nd:YAG laser with a phase-conjugating mirror based on stimulated Brillouin scattering in a SF(6) cell is described. The output energy was up to 300 mJ in 15-ns pulses with shot-to-shot fluctuations of less than 3%. The repetition rate could be varied between 15 and 45 Hz without changes in the spatial-beam profile, which was close to a TEM(00) mode.

The overall hydrolytic constant β3 for the Ac3+ ion has been determined in aqueous solution containing NaClO4 (μ=0.1) by means of the electromigration technique in free electrolyte solution.

The hydrolytic behavior of trace quantities of tetra- and pentavalent vanadium has been studied by the zone electrophoresis method in a wide pH range (2–12). For the first time, the mobilities of all hydrolytic vanadium forms were determined in dilute nitric acid solutions of ionic strength 0.1M at 298 K.

A good separation of the pair Md-Fm was performed on a spheroidal cation exchanger OSTION by means of ammonium α-hydroxy-α-methylbutyrate. The sepation factors and the position of elution peaks for elements of pairs Md-Fm and Ho-Dy are similar.

The corrosion behaviour of iron and steel in aerated neutral NaCl and Na 2 SO 4 solutions in mainly determined by the transport-controlled cathodic oxygen reduction. Its reaction zone depends on the physical and chemical properties of the 3-D layer formed on the corroding surface. The influence of hydrodynamics is restricted to the transport of the dissolved oxygen to the reaction zone. The obtained results are independent of laminar or turbulent flow conditions

Objective: Tissue engineered blood vessels (TEBV) represent an innovative approach to overcome reconstructive problems associated with extended vascular diseases by providing small calibre vasular grafts. The aim of this study was to evaluate a novel biomaterial of bacterially synthesized cellulose (BC) as a potential scaffold for TEBV. Methods: Crystalline cellulose was produced by a bacterium (Acetobacter xylinum) using glucose as carbon source. Tubes of BC were created with a length of 10mm an inner diameter of 3.0–3.7mm and a wall-thickness of 0.6–1.0mm. These grafts were used to replace the carotid arteries of 8 pigs. After a follow-up period of 3 months grafts were removed and analyzed both macro- and microscopically. Results: After 3 months, seven grafts (87.5%) were patent whereas one graft was occluded. Scanning electron microscopy revealed complete recellularization by recipient endothelial cells. Light microscopy showed a three-layered wall structure of the BC-segments with cellulose still being present in the media. Conclusion: These data demonstrate the potential of BC engineered grafts for small calibre vessel substitution. As the innovative BC engineering technique can provide stable small calibre vascular conduits of any desired size and length it offers a highly attractive approach for future TEBV programs in cardiovascular surgery.

The synthesis, via nuclear fusion reactions, of elements heavier than the actinides, allows one to probe the limits of the periodic table as a means of classifying the elements. In particular, deviations in the periodicity of chemical properties for the heaviest elements are predicted as a consequence of increasingly strong relativistic effects on the electronic shell structure1,2,3,4,5,6,7. The transactinide elements have now been extended up to element 112 (ref. 8), but the chemical properties have been investigated only for the first two of the transactinide elements, 104 and 105 (refs 9,10,11,12,13,14,15,16,17,18,19). Those studies showed that relativistic effect render these two elements chemically different from their lighter homologues in the same columns of the periodic table (Fig. 1). Here we report the chemical separation of element 106 (seaborgium, Sg) and investigations of its chemical behaviour in the gas phase and in aqueous solution. The methods that we use are able to probe the reactivity of individual atoms, and based on the detection of just seven atoms of seaborgium we find that it exhibits properties characteristic of the group 6 homologues molybdenum and tungsten. Thus seaborgium appears to restore the trends of the periodic table disrupted by relativistic effects in elements 104 and 105.

A survey is given about efforts undertaken during the HINDAS project to investigate the energy dependence of residual nuclide production by proton‐induced reactions from thresholds up to 2.6 GeV. For proton‐induced reactions, our experiments aimed to further develop and complete the cross‐section database that was established by our collaboration in recent years. It was extended to the heavy‐target elements Ta, W, Pb, and Bi for energies up to 2.6 GeV. In addition, new measurements for the target element iron were performed up to 2.6 GeV and for natural uranium for energies from 21 MeV to 69 MeV. For the target element lead, a comprehensive set of excitation functions published recently was completed by AMS‐measurements of cross sections for the production of the long‐lived radionuclides Be‐10, Al‐26, Cl‐36, and I‐129 and by mass spectrometric measurements for stable and radioactive rare gas isotopes of He, Ne, Ar, Kr, and Xe. Comprehensive tests of the nuclear‐reaction codes TALYS and INCL4+ABLA, which were developed within the HINDAS project, were performed with the new experimental results over the entire energy range.

Chemical separation procedures were developed that allow isolating the iodine, chlorine, aluminium, and beryllium fraction from lead targets irradiated with protons in an energy range up to 2.6 GeV. The cross sections of the four nuclides 10Be, 26Al, 129I, and 36Cl were determined; their excitation functions were calculated and compared with theoretical predictions developed within the HINDAS collaboration (EC 5th framework).

The local magnetic behavior of recoil-implanted isolated Sc ions has been studied in II–VI and other semiconducting compounds. In all cases nonmagnetic configurations were observed consistent with an empty d-shell of the Sc ion. Additionally a different influence of nearby defects on the Sc probe ion was observed in the various types of compound semiconductors.

Essential techniques that allow further scaling of trench DRAMs beyond 100 nm have been developed. Al/sub 2/O/sub 3/ was implemented as a high-k node dielectric in silicon-insulator-silicon trench capacitors. Al/sub 2/O/sub 3/ films were deposited by ALD with excellent step coverage at aspect ratios of up to AR/spl ap/60. Even after thermal stressing at 1050/spl deg/C an effective oxide thickness (=capacitance equivalent thickness) of t/sub ox/=3.6 nm and a leakage current of well below 1 fA/cell were obtained. Both selective and non-selective HSG Si was formed inside high-aspect ratio straight and bottled trenches. On fully integrated 0.17 /spl mu/m trench DRAMs, a storage capacitance of 45 fF/cell with acceptable leakage current was achieved. Both the aluminum oxide node dielectric and the HSG silicon have thus been proven to withstand the high thermal budget required for integration into trench DRAMs. In addition, a silicon etch process was developed that allows trench aspect ratios of AR/spl ap/60 at critical dimensions of CD=80 nm.

Ion mobilities of silver, cobalt, zinc, gadolinium and europium and their complexonates with NTA, EDTA and DTPA are determined. It is shown that – contrary to the published data the ion mobility of complexonates does not depend on the mobility of the central cation; – complexonates with equal charges show similar mobilities, the deviation being not more than 15% of the average value; – a tendency for the ion mobility to decrease with increasing molecular weight of the complexonate is observed.

FMRFamide is a molluscan peptide that has shown antiopiate activity in a number of mammalian test systems. Peptidomimetics of FMRFamide substituted with conformationally constrained stereoisomers of Z -2,3-methanomethionine or E -2,3-methanomethionine precipitated abstinence syndrome far more potently than FMRFamide itself. The current study determined the effect on antiopiate potency of an additional rigid substitution. A peptidomimetic containing a stereoisomer of E -2,3-methanomethionine was compared with a peptidomimetic additionally substituted at the C -terminal with E -2,3-methanophenylalanine. Morphine abstinence signs were observed after varying doses (0.125–25.0 μg) of these two peptidomimetics were injected into the third ventricle of morphinedependent rats. The peptidomimetic containing both rigid substitutions was far more potent than the peptidomimetic of FMRFamide containing methanomethionine alone. The increased potency appears to be related to enzyme resistance rather than receptor affinity.

Using the electromigration method the monopositive astatine ion has been shown to form EDTA [H4L] complexes in 0.1M NaClO4 solution at pH=3–10. The ion mobility of the AtL3− complex is 5.60/23/x10−4 cm2.V−1.s−1.

Summary Peracetic acid Wofasteril®) is increasingly made use of as a disinfecting fluid. Because of its high effectiveness it has found widespread use in medical practice. The action of Wofasteril® on the oral mucosa during long-term action is studied by aid of an “oral tank”. After a test period of 11 months peracetic acid only caused a slight ballooning of the superficial layers and enhanced vascularization of the submucous tissue. The results of the experiment suggest the intraoral administration of peracetic acid in oral surgery and stomatology.

Es werden die RAMAN-Spektren der Methan- und Athanseleninsaure in verschiedenen Zustanden (fest, in H2O, in CH3OH) sowie die IR-Spektren in KBr mitgeteilt und diskutiert. Starke H-Bruckenbindungskrafte, die in der Methanverbindung etwas starker sind, bewirken sowohl im festen Zustand als auch in Losung Assoziation. Die Athanseleninsaure existiert in Losung (in H2O, in CH3OH, in KBr) in zwei rotationsisomeren Strukturen. Keine der Sauren wird durch Methanol im Gegensatz zur selenigen Saure und den alkylselenigen Sauren verestert. Einige chemische, physikalische und physiologische Eigenschaften werden angegeben. The RAMAN-spectra of CH3SeO2H and C2H5SeO2H in different states (solid, in H2O, in CH3OH) and the IR-spectra in KBr are given and discussed. Strong H-bonds, which are strongest in CH3SeO2H, cause association in solid and in solved state. The molecule C2H5SeO2H forms in solution (in H2O, in CH3OH, in KBr) two rotational isomeric configurations. In contrast to the compounds H2SeO3 and RO · SeO · OH, methanol does no esterify CH3SeO2H and C2H5SeO2H. Some chemical, physical, and physiologic properties are given.

Am Beispiel der Schmelzepolykondensation von Polyathylenterephthalat (PETP) wird gezeigt, das die Gesamtreaktionsgeschwindigkeit vom Abtreiben des Reaktionsglykols bestimmt wird. Vorliegende Untersuchungen beschrankten sich auf das erste Stadium der Polykondensation, in dem die Turbulenz infolge des freiwerdenden Glykols ziemlich gros ist. In einem vorgegebenen Reaktor ohne bewegte Innenteile wurde das Fortschreiten der Polykondensation von PETP durch volumetrisches Erfassen des Reaktionsglykols verfolgt. Auser der Schichtdicke wurde der Unterdruck (von etwa 40 bis 100 Torr) variiert, wobei bei einigen Versuchen zur besseren Durchmischung bzw. zur Keimbildung auserdem Stickstoff eingeleitet wurde (bis 10 l/h). Nach differentieller kinetischer Auswertung schwankt die Ordnung der Bruttoreaktion je nach Turbulenz des Systems zwischen etwa 2 und 7,5. Bei derartig grosen Zahlen mus es sich um eine formale Ordnung handeln, und der Gedanke liegt nahe, das die Gesamtreaktionsgeschwindigkeit der Polykondensation vom Stofftransport des Reaktionsglykols bestimmt wird. Dies wurde unter einigen vereinfachenden Annahmen nach der Zweifilmtheorie untersucht. In Analogie zur Ermittlung der SHERWOOD-Zahl wurde ein Potenzansatz zugrundegelegt: F · β = C · Re′m; in dem F die Phasengrenzflache, β der Stoffubergangskoeffizient und Re′ die (modifizierte) REYNOLDS-Zahl sind. Wahrend die Werte des rein chemischen Mechanismus, namlich die Ordnung und die Reaktionsgeschwindigkeitskonstante, auserordentlich schwanken, liegen die Konstanten C und vor allem m, der sog. REYNOLDS-Index, ziemlich dicht beieinander. Die Vorkondensation kann demnach innerhalb der Grenzen der Variablen gut mit dem Stoffubergangs-Ansatz beschrieben werden. Russian Abstract. By considering the melt polycondensation of polyethylene terephthalate as an example, the overall reaction rate is shown to be determined by expelling the glycol formed in the reaction. The investigations performed are limited to the first stage of the polycondensation process, the pre-condensation, in which the turbulence caused by the given off glycol is comparatively high. In a reactor having only stationary internal parts the polycondensation process of PETP was traced by volumetric measurement of the glycol given off. Besides the layer thickness, the pressure was varied between 40 and 100 Torr. In some experiments up to 10 l/h nitrogen was injected for more intimate mixing and nucleation. In evaluating the kinetic equations the order of the overall reaction was found to vary between about 2 and 7.5, depending on the turbulence in the system. These high values suggest the overall rate of reaction to depend on the mass transport of the glycol evolved. The validity of this suggestion was investigated by a double layer method base on some simplified assumptions. In analogy to the determination of the SHERWOOD number the expression F. β = C. Re′m, with Re′ as modified REYNOLDS number to the power m, F area of the phase interface and β mass transfer coefficient, was used. While the values of the chemical mechanism, as expressed in the order of the rate constant, are subject to extremely high variation, the values of C and particularly those of the REYNOLDS index m keep fairly close to one another. This leads to results allowing to describe the precondensation within the variables of the expression proposed for the mass transfer.

Es werden die RAMAN-Spektren der Verbindungen CH3SeOOH · HCl und C2H5SeOOH · HCl im festen Zustand und in wasriger Losung sowie die IR-Spektren dieser Verbindungen suspendiert in Nujol und geprest in KCl mitgeteilt und diskutiert. Es ergibt sich eine Struktur der allgemeinen Formel [R–Se(OH)2]Cl mit 2 SeO-Einfachbindungen. Die Ionen sind im Gitter uber H-Brucken miteinander verbunden. In wasriger Losung findet geringe Dissoziation des Kations zur freien Saure statt. Das [C2H5Se(OH)2]⊕-Ion liegt in wasriger Losung in zwei rotationsisomeren Konfigurationen vor. The RAMAN-spectra of the compounds CH3SeOOH · HCl and C2H5SeOOH · HCl in solid state and in aqueous solutions as well as the IR-spectra of these compounds suspended in nujol or pressed in KCl are given and discussed. It results a structure with the general formula [R–Se(OH)2] Cl with two SeO-single bonds. The ions are connected in the lattice by H-bonds. Low dissociation of the cation occurs in aqueous solution. The ion [C2H5Se(OH)2]⊕ exists in aqueous solution in two rotational isomeric configurations.

From the leaves of Pleiocarpa tubicina STAPF (+)-Quebrachamine ((+)-I), (−)-1,2-Dehydroaspidospermidine (( −)-II), and (−)-Aspidofractinine (IV), have been isolated in small quantities. The interesting conversion of (−)-Quebrachamine ((−)-I) into(+)-1,2-Dehydroaspidospemidine ((+)-II) has been achieved by controlled per-manganate oxidation.

Zusammenfassung Δ 9 -N-Methyloctahydrochinolin addiert Butadiencarbonester unter Bildung von zwei epimeren ungesattigten Estern 7a und 7b . Die Addition erfolgt ausschliesslich an das Δ 8 -Isomere 6b .

Es werden von (CH3)2AsO2H (zum Teil deuteriert) und (C3H5)2AsO2H sowie von deren Reaktionsprodukten mit HCl die IR- und RAMAN-Spektren, fest und in konzentrierter wasriger Losung, mitgeteilt. Das Dialkylarsinsauregerust besitzt die Raumgruppe Cs, das Arsinatacidiumion mit groser Wahrscheinlichkeit C2V. Wahrend die Kakodylsaure mit HCl lediglich ein Anlagerungsprodukt (CH3)2AsO2H · HCl (Bindung uber H-Brucken) ergibt, vermag die schwachere Diathylarsinsaure ein Acidiumsalz [(C2H5)2As(OH)2]Cl zu bilden. Die Wasserstoffbrucken in den Verbindungen werden diskutiert. RAMAN and IR Spectroscopic Investigation on Alkyl Derivatives of Arsenic-Acid. V. Vibrational Spectra of Dimethyl and Diethyl Arsinic Acid and their Reaction Products with HCl The RAMAN and IR spectra of (CH3)2AsO2H–partially deuterated–and (C2H5)2AsO2H and of the reaction products of these acids with HCl (solid and in concentrated aqueous solution) are discussed. The symmetry of the R2AsO2H skeleton is Cs. of the [R2As(OH)2]+ ion very probably C2v. Whereas (CH3)2AsO2H gives with HCl only a compound (CH3)2ACO2H · HCl (connected by H bonds), the weaker (C2H5)2AsO2H is able to form a salt [(C2H5)2As(OH)2]Cl. The H bonds in the substances are discussed.

Es werden die RAMAN-Spektren von CH3AsO3H2, C2H5AsO3H2 und CH3AsO3HNa · 3/2 H2O (fest und in gesattigter bzw. konzentrierter wasriger Losung) sowie die IR-Spektren (400–4000 cm−1) der festen, zum Teil deuterierten Sauren und des Hydrogenarsonates mitgeteilt und diskutiert. Diese Verbindungen weisen mit sehr groser Wahrscheinlichkeit die Symmetrie Cs auf. Aus dem IR-Spektrum (zwei starke, breite OH-Valenzbanden um 2820 wad 2350 cm−1, die OH-Deformationsschwingung um 1220 cm−1) mus auf die Ausbildung ziemlich starker Wasserstoffbruckenbindungen geschlossen werden. RAMAN and IR-spectroscopic Investigation of Alkyl Derivatives of Arsenic Acid. III. The Vibrational Spectra of Methane and Ethanearsonic Acid and Sodium Hydrogenmethanearsonate. The RAMAN spectra of CH3AsO3H2, C2H5AsO3H2 CH3AsO3HN2. 3/2 H2O (solid and in concentrated aqueous solution) and the IR spectra (400 -4000 cm−1) of these solid acids – partially deuterated – and of the hydrogenarsonate are discussed. The very probable symmetry of these compounds is Cs. As the IR spectra show (two strong broad OH valence bands at 2820 and 2350 cm−1; OH deformation frequency at 1220 cm−1), rather strong H-bonds exist in these acid substances.

Es werden die RAMAN- und IR-Spektren des Lithium-, Natriumund Kaliummethanarsonates sowie die des Natrium- und Kaliumathanarsonates (zum Teil mit Kristallwasser) mitgeteilt und diskutiert. Die Spektren zeigen kaum Kopplung zwischen Alkyl- und AsO3-Gruppe, so das beide getrennt behandelt warden konnen. Fur die AsO3-Gruppe ergibt sich die Symmetire C3v, wobei jedoch entartete und symmetrische AsO3-Valenzfrequenz sehr dicht beieinander liegen, so das sie nur im festen Zustand sichtbar gemacht werden konnen. Im Lithiumsalz werden Frequenzen um 500 cm−1 beobachtet, die als O…LiO-Valenzchwingungen gedeutet werden mussen (Elektronenmangeleffekt). RAMAN and IR-spectroscopic investigation of alkyl derivatives of arsenic acid. I. Vibrational spectra of some alkali metal alkanearsonates The RAMAN and IR spectra of Lim, Na and K methanearsonate and those of Na and K ethanearsonate (some of them being in the hydrated form) are communicated group. For the latter, symmetry C3v is established, with the degenerate and the symmetric AsO3 valence frequencies lying in direct neighbourhood and being resolved only in the solid state spectra. LiO valence modes are observed at about 500cm−1.

The absolute configuration of a number of aspidospermine alkaloids has previously been suggested by a correlation of their molecular rotations with those of some strychnine alkaloids. This correlation is now strengthened and extended by a study of the optical rotatory dispersion (ORD) curves.

Die Alkaloide C-Mavacurin, C-Fluorocurin und C-Alkaloid Y aus Calebassen-Curare und sudamerikanischen Strycknos-Arten sind mit dem Indolalkaloid Pleiocarpamin aus Pleiocarpa mutica BENTH. und Hunteria eburnea PICHON in Beziehung gesetzt worden. Diese Beziehungen erlauben die Festlegung der Natur der Hydroxyl-gruppe in den Curare-Alkaloiden und machen in den fruher abgeleiteten Formelneine Abanderung des Ringes E im Sinne der neuen Formeln 8,16 und 19 notwendig;daraus folgt auch die Strukturformel 1 fur Pleiocarpamin. Weitere chemische Um-wandlungen stutzen diese Formeln und ermoglichen die Ableitung der relativen Stereochemie der Alkaloide. 100-MHz-Protonenresonanz-Spektren zusammen mit Spin-Entkoppelungs-Experimenten erlaubten die Identifizierung aller fur das Ringgerust charakteristischen Protonen und eine unabhangige Ableitung der stereochemischen Verhaltnisse. Schliesslich werden noch die Massenspektren der Alkaloide und ihrer Derivate diskutiert.

Der massenspektrometrische Abbau von Hydroxyderivaten des Sparteins ist in vielen Fallen sehr stark von der Stellung der funktionellen Gruppe abhangig, so das auf Grund der Massenspektren dieser Verbindungen die Lokalisierung des Substituenten in einem bestimmten Molekulteil moglich ist.

Durch Erhitzen large sich das aus Tubotaiwin erhaltliche Indolenin Condyfolin teilweise in Tubifolin und reversibel in 20-epi-Condyfolin um. Tubifolin und Condy-folin liefern mit Kaliumboranat die selbe Indol VIII, das sich durch Dehydrierung mit Sauerstoff wiederum in Tubifolin und Condyfolin zuruckumwandeln lasst. Durch diese Umwandlungen finden die fur Condylocarpin und Tubotaiwin aufgestellten Strukturen eine Bestatigung; gleichzeitig ist damit die absolute Konfi-guration dieser Alkaloide und des Stemmadenins bestimmt. In allen diesen Alka-loiden besitzt das Zentrum 15 dieselbe absolute Konfiguration. Auf die mogliche Bedeutung des Indols X als Vorlaufer fur die Biogenese dieser Alkaloide wird hinge-wiesen.

Es werden die Raman- und IR-Spektren des Natrium- und Kaliumsalzes der Dimethyl-(=Kadodylsaure) und Diathylarsinsaure (zum Teil in Hydratform) mitgeteilt und diskutiert. Das Arsinatgerust C2AsO weist mit sehr groser Wahrscheinlichkeit die Symmetrie C2v auf. Raman and IR-spectroscopic Investigation of Alkyl Derivatives of Arsenic Acid. IV. Vibrational Spectra of Some Dialkylarsinates The Raman and IR spectra of the Na and K salt of the dimethyl- and diethylarsinic acid (in part as hydrate) are discussed. The skeleton C2AsO shows very probably the symmetry C2v.

Derivate von Chinolizidinalkaloiden, die eine Lactamfunktion enthalten, werden im Vergleich zu den Grundkorpern in verschiedener Weise abgebaut: Bei Gegenwart eines basischen Amin-und eines nichtbasischen Amid-stickstoffatoms erfolgt die Ionisation bevorzugt am basischen N-Atom. Dieses induziert also die Hauptabbaureaktionen, in deren Verlauf fast immer der die Lactamgruppe enthaltende Teil des Molekuls eliminiert wird. Aus den Spektren sind daher Ruckschlusse auf die Lage der Lactamgruppierung moglich.