bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of the formation and conversion of unstable thionyl isocyanate: Gas-phase spectroscopic studies
Authors: Wang Weigang , Yao Li , Zeng Xiaoqing , Ge Maota , Sun Zheng , Wang Dianxun , Ding Yihong
Published: December 2006

Thionyl diisocyanate which is unstable at ambient temperature is generated from a heterogeneous reaction of gaseous thionyl dichloride with silver cyanate and studied for the first time in the gas phase at 298K. N-isocyanatoformyl sulfinylimide is also observed with photoelectron spectroscopy in the gas phase for the first time. The conversion of thionyl diisocyanate to N-isocyanatoformyl sulfinylimide via 1,3 shift at different temperatures is studied by using photoelectron spectroscopy and mass spectroscopy with the help of theoretical computations. On the basis of combined observations and quantum chemical calculations, possible 1,3-isocyanato shifts and dissociation processes for thionyl isocyanate and its cation have been discussed in detail.
Hydrogen bond and residence dynamics of ion–water and water–water pairs in supercritical aqueous ionic solutions: Dependence on ion size and density
Authors: Mallik Bhabani S. , Chandra Amalendu
Published: December 2006

We have carried out a series of molecular dynamics simulations to investigate the hydrogen bond and residence dynamics of X−–water (X=F, Cl, and I) and pairs in aqueous solutions at a temperature of 673 K. The calculations are done at six different water densities ranging from 1.0 to 0.15 g cm−3. The hydrogen bonds are defined by using a set of configurational criteria with respect to the anion(oxygen)–oxygen and anion(oxygen)–hydrogen distances and the anion(oxygen)–oxygen–hydrogen angle for an anion(water)–water pair. The F−–water hydrogen bonds are found to have a longer lifetime than all other hydrogen bonds considered in the present study. The lifetime of Cl−–water hydrogen bonds is shorter than that of F−–water hydrogen bonds but longer than the lifetime of water–water hydrogen bonds. The lifetimes of I−–water and water–water hydrogen bonds are found to be very similar. Generally, the lifetimes of both anion–water and water–water hydrogen bonds are found to be significantly shorter than those found under ambient conditions. In addition to hydrogen bond lifetimes, we have also calculated the residence times and the orientational relaxation times of water molecules in ion(water) hydration shells and have discussed the correlations of these dynamical quantities with the observed dynamics of anion(water)-water hydrogen bonds as functions of the ion size and density of the supercritical solutions.
Driving forces behind ion-ion correlations
Authors: Lund Mikael , Jönsson Bo
Published: December 2006

Within the primitive model of electrolytes, partitioning the system free energy into contributions from entropy and energy requires an explicit description of the temperature dependence of the dielectric constant ϵr. Taking this into account, the authors find that the ion-ion correlation attraction between like charged macroions is governed by entropy and not energy as often argued. The authors have exemplified this via Monte Carlo simulations and show how ∂ϵr∕∂T turns the “traditional” picture upside down.
Atmospheric-pressure hybrid plasma with combination of ac and microwave
Authors: Hong Yong Cheol , Uhm Han Sup
Published: December 2006

A hybrid plasma system with combination of ac and microwave at atmospheric pressure was developed. The hybrid plasma is initiated by ac capillary plasma, is stabilized by a flowing channel of working gas through common electrodes, and is expanded by the dissipation of microwave energy, revealing two distinguishable plasma columns of about 1m in length and a transition point. The capillary in the hybrid plasma system is working as a common electrode for the microwave and ac plasmas. Optical emission spectroscopy is used to characterize and monitor the argon and nitrogen excited species produced in different plasma columns.
Effect of dual frequency on the plasma characteristics in an internal linear inductively coupled plasma source
Authors: Kim K. N. , Lim J. H. , Yeom G. Y. , Lee S. H. , Lee J. K.
Published: December 2006

An internal-type linear inductive antenna, referred to as a “double comb-type antenna,” was used as a large area plasma source with a substrate size of 880×660mm2 (fourth generation glass size). The effects of the dual frequency (2 and 13.56MHz) radio frequency (rf) power to the antenna as well as the power ratio on the plasma characteristics were investigated. High-density plasma on the order of 1.7×1011cm−3 could be obtained with a dual frequency power of 5kW (13.56MHz) and 1kW (2MHz) at a pressure of 15mTorr Ar. This plasma density was lower than that obtained for the double comb-type antenna using a single frequency alone (5kW, 13.56MHz). However, the use of the dual frequency with a rf power ratio of approximately 1(2MHz):5(13.56MHz) showed better plasma uniformity than that obtained using the single frequency. Plasma uniformity of 6.1% could be obtained over the substrate area. Simulations using FL2L code confirmed the improvement in the plasma uniformity using the dual frequency to the double comb-type antenna.
Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided optical fiber
Authors: Siegman A. E. , Chen Ying , Sudesh Vikas , Richardson Martin C. , Bass Michael , Foy Paul , Hawkins Wade , Ballato John
Published: December 2006

The authors report laser oscillation in what appears to be a single transverse mode with very large mode area in optical fibers having heavily Nd-doped 100μm diameter cores with refractive index significantly lower in the core than in the surrounding cladding. Since fibers of this type cannot support conventional index-guided modes, their results appear to confirm a recent analysis which predicts gain-guided single-mode propagation in index antiguided fibers, provided the gain coefficient in the core exceeds a threshold value. Fibers of this type may be of significant interest for amplifiers and oscillators having large power outputs and/or small nonlinear pulse distortion.
Ultrafast ion emission from metallic tip excited by femtosecond laser pulses
Authors: Vella A. , Gilbert M. , Hideur A. , Vurpillot F. , Deconihout B.
Published: December 2006

Using femtosecond time resolved measurements of the ion evaporation flux from a metal tip, the authors study the temporal behavior of ion emission a few femtoseconds after the incident ultrashort laser pulse. The authors show that the ultrafast response of surface electrons generates a very short and intense ion emission. Also a weak heating of the specimen was observed leading to the increase of the ion emission rate. The observed ultrafast ion emission is consistent with the model based on the rectification of the optical field at the surface of the material.
Optical in situ size determination of single lanthanide-ion doped oxide nanoparticles
Authors: Casanova Didier , Giaume Domitille , Beaurepaire Emmanuel , Gacoin Thierry , Boilot Jean-Pierre , Alexandrou Antigoni
Published: December 2006

We show that the size of a lanthanide-ion doped nanoparticle can be accurately determined from its luminosity. The optically determined size distribution is in very good agreement with the distribution obtained from transmission electron microscopy. These data confirm that single nanoparticles are visualized in microscopy experiments. Nanoparticles as small as 13nm are detectable with integration times of 500ms.
Evolution of buried semiconductor nanostructures and origin of stepped surface mounds during capping
Authors: Katsaros G. , Rastelli A. , Stoffel M. , Costantini G. , Schmidt O. G. , Kern K. , Tersoff J. , Müller E. , von Känel H.
Published: December 2006

The authors apply selective wet chemical etching and atomic force microscopy to reveal the three-dimensional shape of SiGe∕Si(001) islands after capping with Si. Although the “self-assembled quantum dots” remain practically unaffected by capping in the temperature range of 300–450°C, significant morphological changes take place on the Si surface. At 450°C, the morphology of the capping layer (Si matrix) evolves toward an intriguing semifacetted structure, which we call a “ziggurat,” giving the misleading impression of a stepped SiGe island shape.
Polymeric waveguide biosensors with calixarene monolayer for detecting potassium ion concentration
Authors: Oh Min-Cheol , Kim Kyung-Jo , Lee Jae-Hyun , Chen Hong-Xia , Koh Kwang-Nak
Published: December 2006

Biophotonic sensors based on a polymer waveguide with Bragg reflection gratings are proposed in this work. For developing low-cost disposable sensors, UV curable polymer materials are utilized to demonstrate the waveguide sensors. The grating pattern is formed on the core layer of a polymer waveguide by exposing a laser interference pattern on a photoresist. To detect a small amount of analyte molecule through a specific binding, a calixarene crown molecule is immobilized on a sensing interface. Bragg reflection peak movement is observed depending on the potassium ion concentration dissolved in phosphate buffered saline solution. It has been confirmed experimentally that the sensor could detect the potassium ion concentration on the order of 1pM.
Temperature dependence of working pressure of a nanoporous liquid spring
Authors: Qiao Yu , Punyamurtula Venkata K. , Han Aijie , Kong Xinguo , Surani Falgun B.
Published: December 2006

The thermal effect on nanofluidic behaviors in a hydrophobic zeolite is investigated experimentally. At a constant temperature, water can be forced to infiltrate into the nanopores as an external pressure is applied and defiltrate as the pressure is lowered, leading to a springlike pressure-volume relationship. As temperature varies, due to the variation in solid-liquid interfacial tension, the infiltration pressure changes significantly. Consequently, the system exhibits a thermally controllable volume memory characteristic, with the energy density higher than that of ordinary shape-memory solids by more than one order of magnitude, providing a promising way for developing high-performance intelligent devices.
Beyond the Galaxy Luminosity Function
Authors: Driver Simon
Published: December 2006

With the advent of large-scale surveys (i.e. Legacy Surveys) it is now possible to start looking beyond the galaxy luminosity function (LF) to more detailed statistical representations of the galaxy population, i.e multivariate distributions. In this review I first summarise the current state-of-play of the B-band global and cluster LFs and then briefly present two promising bivariate distributions: the luminosity–surface brightness plane (LSP) and the colour–luminosity plane (CLP). In both planes galaxy bulges and galaxy disks form marginally overlapping but distinct distributions, indicating two key formation/evolutionary processes (presumably merger and accretion). Forward progress in this subject now requires the routine application of reliable bulge–disk decomposition codes to allow independent investigation of these two key components.
Substructure in Dwarf Galaxies
Authors: Coleman Matthew
Published: December 2006

Recent years have seen a series of large-scale photometric surveys with the aim of detecting substructure in nearby dwarf galaxies. Some of these objects display a varying distribution of each stellar population, reflecting their star formation histories. Also, dwarf galaxies are dominated by dark matter, therefore luminous substructure may represent a perturbation in the underlying dark material. Substructure can also be the effect of tidal interaction, such as the disruption of the Sagittarius dSph by the Milky Way. Therefore, substructure in dwarf galaxies manifests the stellar, structural, and kinematic evolution of these objects.
Luminosity Functions from the 2dF Galaxy Redshift Survey
Authors: Colless Matthew
Published: December 2006

A summary of the main results from the 2dF Galaxy Redshift Survey of over 221 000 galaxies on the galaxy luminosity function and its dependence on surface brightness, spectral type, environment, and local density.
The Stellar Populations of dE Galaxies in Nearby Groups
Authors: Da Costa G. S.
Published: December 2006

In this contribution Gemini-North NIRI J,K-observations are used to investigate the upper-Asymptotic Giant Branch (AGB) intermediate-age population in the M81 Group dwarf elliptical (dE) F8D1. Hubble Space Telescope (HST) ‘snapshot’ V,I-observations are also analysed to investigate the upper-AGB populations in two other M81 Group dEs, DDO 71 and kk077. In all three dEs, significant intermediate-age populations are found. Further, there are sizeable dE-to-dE differences in these populations: F8D1 contains relatively more, and relatively more luminous, upper-AGB stars. These results are compared with existing information for Local Group and Sculptor group dwarfs. It is suggested that ‘environmental harrassment’ plays an important role in governing dwarf galaxy evolution.
Large Scale Structure in the Local Universe — The 2MASS Galaxy Catalog
Authors: Jarrett Thomas
Published: December 2006

Using twin ground-based telescopes, the Two-Micron All Sky Survey (2MASS) scanned both equatorial hemispheres, detecting more than 500 million stars and resolving more than 1.5 million galaxies in the near-infrared (1–2.2 μm) bands. The Extended Source Catalog (XSC) embodies both photometric and astrometric whole sky uniformity, revealing large scale structures in the local Universe and extending our view into the Milky Way's dust-obscured ‘Zone of Avoidance’. The XSC represents a uniquely unbiased sample of nearby galaxies, particularly sensitive to the underlying, dominant, stellar mass component of galaxies. The basic properties of the XSC, including photometric sensitivity, source counts, and spatial distribution, are presented here. Finally, we employ a photometric redshift technique to add depth to the spatial maps, reconstructing the cosmic web of superclusters spanning the sky.
The 2dF Galaxy Redshift Survey as a Cosmological Laboratory
Authors: Lahav Ofer
Published: December 2006

The 2dF Galaxy Redshift Survey (2dFGRS) of 230 000 redshifts of nearby (z ~ 0.1) galaxies is now complete. It has allowed the 2dFGRS Team and others to estimate fundamental cosmological parameters and to study galaxy intrinsic properties. Here we highlight three recent key results from the survey: (a) an upper limit of about 2 eV on the total mass of the three neutrino flavours, and an intriguing reasonable fitting of the 2dFGRS power spectrum to a Mixed Dark Matter model without a Cosmological Constant but with a low Hubble constant; (b) the bimodality of the galaxy population in both spectral parameterisation and in colour; and (c) the clustering of different galaxy types and evidence for relative stochastic biasing.
Light on Dark Matter
Authors: Tully R. Brent
Published: December 2006

Galaxies are lighthouses that sit atop peaks in the density field. There is good observational evidence that these lighthouses do not provide a uniform description of the distribution of dark matter.
Resonance Rayleigh Scattering for the Determination of Chlorpromazine and Promethazine
Authors: An Lanxiang , Liu Shaopu , Liu Zhongfang , Kong Ling , Hu Xiaoli
Published: December 2006

Chlorpromazine (CPZ) and promethazine (PZ) can react with potassium ferrioxalate (PF) to form 3:1 ion-association complexes, which can result in a significant enhancement of resonance Rayleigh scattering (RRS) intensity. The maximum scattering peaks are located at 368 nm for CPZ-PF and 370 nm for PZ-PF. The RRS spectroscopic characteristics, the optimum conditions of reactions, and influencing factors have been studied for CPZ-PF and PZ-PF. There is a linear relationship between the RRS intensity and the drug concentration in the range of 0.02–8.00 μg mL–1 for CPZ and 0.04–9.00 μg mL–1 for PZ, and the detection limits (3σ) are 6.6 ng mL–1 for CPZ and 10.6 ng mL–1 for PZ. The proposed method has been applied to determine CPZ in urine and serum samples with satisfactory results. Moreover, the reaction mechanism and the reasons for intensity enhancement of RRS have been discussed.
Efficient Synthetic Method for β-Enamino Esters Catalyzed by Yb(OTf)3 under Solvent-Free Conditions
Authors: Varala Ravi , Nuvula Sreelatha , Adapa Srinivas R.
Published: December 2006

A wide range of β-enamino esters have been synthesized in moderate to excellent yields by reacting 1,3-dicarbonyl compounds with amines in the presence of catalytic amounts of Yb(OTf)3 (2 mol%). The reaction proceeds smoothly at ambient temperature under solvent-free conditions. The catalyst can be recovered and reused.
The System ABXY in Nuclear Magnetic Resonance Spectroscopy
Authors: Riggs NV
Published: December 2006

The 4 x 4 secular
determinant that arises in the quantum mechanical treatment of the system ABXY
in N.M.R. spectroscopy can be solved exactly under one of three limiting
conditions. A close approximate extension of one of these allows the general
ABXY spectrum to be analysed. The exact solution for JXY = 0 is
applied to the pyridine-ring protons of nicotine.
Mono- and Bis-(2,2'-bipyridine) and -(1,10-phenanthroline) Chelates of Ruthenium and Osmium. II. Bischelates of Bivalent and Tervalent Ruthenium
Authors: Dwyer FP , Goodwin HA , Gyarfas EC
Published: December 2006

Bis(phenanthro1ine) and
bis(bipyridine)ruthenium(~~) chelates have been prepared by the pyrolysis, at
300�C, of phenanthrolinium tetrachlorophenanthrolineruthenate(III) and
bipyridinium tetrachlorobipyridineruthenate(III). In the complexes [RuB2Cl2]
the chelating base molecules are firmly bound but the chlorine atoms are
replaceable by a variety of ligands such as water, pyridine, or acetylacetone.
The complexes are spin-paired and show no tendency to disproportionation to the
tris complexes, under normal experimental conditions.
Faradaic Admittance and Migration in the Diffuse Double-Layer: Effect on the Phase Angle
Authors: Narayanan K , Rangarajan SK
Published: December 2006

The effect of migration in the diffuse
double-layer on the phase angle between the alternating components of the
faradaic current and voltage is discussed. It is shown that the cot � v. √ω
relationship is nonlinear and the modified equation for this case (i.e. when
migration is taken into account) is given. Equations derived already by Matsuda
are discussed. Theoretical studies on the variation of ((Io)app/(Io)ms
with Gouy potential are also reported.
Studies in Mass Spectrometry. VII. Triterpenoids: Ifflaionic Acid
Authors: Shannon JS
Published: December 2006

The mass spectra of the methyl ester of
the new unsaturated pentacyclic triterpenoid ifflaionic acid
(urs-12-en-3-on-30-oic acid) and some of its chemical derivatives are
presented. These may be used to assign position C-20 to the carbomethoxy and C-3
or C-7 to the keto group. Mechanistic proposals for, and the effect of
functional groups on, the main fragmentation of the molecular ions (cleavage
through ring C) are discussed.
Isomerism in Alkyltin Compounds
Authors: Cummins RA
Published: December 2006

The origin of two bands, one near 500 cm-1
and the other near 600 cm-1 found in liquid alkyltin compounds has
been studied. They are shown to arise from two isomeric forms. The isomerism
arises from the conformation of the alkyl chain with respect to the tin atom.
Both bands are assigned to tin-carbon stretching frequencies, the higher
frequency to the trans-isomer and the lower to the gauche.
The Stereochemistry of Rings A and B in 6-Substituted Δ4-3-Oxosteroids: A Study of H1 Allylic Spin-Spin Coupling in Systems with Defined Geometry
Authors: Collins DJ , Hobbs JJ , Sternhell S
Published: December 2006

The preparation of some
6-substituted A4-3-oxosteroids is described. As previously announced, the
stereochemistry at the 6-position, which is of importance in connection with
biological activity, may be deduced from examination of the N.M.R. signal due
to the vinylic proton at C4 which appears as a singlet (WH
= 1.5 - 1.8 c/s)in the 6β-substituted series and as a doublet (J = 1.6
- 1.8 c/s) in the 6α-substituted series. The general dependence of the
allylic coupling constants on stereochemistry is examined and an empirical
angular relation shown to exist, with the coupling constant at a maximum when
the angle subtended between the allylic and vinylic protons is 90� and at a
minimum when it is 0 or 180�. Theoretical implications are briefly considered.
Proton Magnetic Resonance Spectra of Nitronaphthalenes in Dimethylacetamide Solution
Authors: Wells PR , Alcorn PGE
Published: December 2006

Examination of the proton magnetic
resonance spectra of some methyl and dimethyl derivatives of 1- and
2-nitronaphthalene has allowed assignments of spectral regions to the various
ring protons to be made. The individual proton resonances and overall spectral
patterns correspond well with those predicted from studies of the dinitronaphthalenes
and dimethylnaphthalenes. Steric crowding in 2-methyl-1-nitronaphthalenes
appears to reverse the proximity effect of the nitro group on the
peri-hydrogen.
Organoaluminium compounds. IX. Inhibition by coordinating solvents of the reaction of trimethylaluminium with triethylaluminium
Authors: Mole T
Published: December 2006

Reaction of trimethylaluminium with
triethylaluminium to give dimethylethylaluminium and methyldiethylaluminium is
complete within a few seconds in mixtures of benzene with ether or
tetrahydrofuran at 40�. Reaction in pyridine occurs more slowly and requires
several minutes at 90�.
Studies of aromaticity by nuclear magnetic resonance spectroscopy. IV. The proton chemical shifts in Cycl[3,2,2]azine
Authors: Jackman LM , Porter QN , Underwood GR
Published: December 2006

The n.m.r, spectra of cycl[3,2,2,]azine
and some derivatives have been examined. The spectral assignments made by
Boekelheide at al. for cycl[3,2,2]azine hare been confirmed by arguments which
are independent of MO calculations.

SCFMO calculations of the proton chemical
shifts in cycl[3,2,2]azine are in reasonable agreement with the observed
values.
The structure and formation of voaluteine
Authors: Guise GB , Ritchie E , Taylor WC
Published: December 2006

Voaluteine is shown to be the ψ-spiro-indoxyl
related to voacangine and is thus probably an artefact. Its formation from
voacangine by oxidation reactions has been investigated. Experiments on the
formation of β-hydroxyindolenines from indoles via their Grignard
derivatives and oxygen are described.
The absolute stereochemistry of piptoside and dihydropiptosidin
Authors: Lowry JB , McAlpine JB , Riggs NV
Published: December 2006

The absolute
stereochemistry of piptoside and dihydropiptosidin has been determined at C5,
C6 and C7 by comparison of dihydropiptosidin and leucodrin by means of
molecular-rotation changes and p.m.r. spectroscopy,
and by application of Horeau's method. Examination of
p.m.r. parameters of some piptoside derivatives
allows a tentative formulation at C4 and, together with previous results,
allows the absolute stereochemistry of piptoside to be written as
2S,3S,4S,5S,6R,7S.
An on-line ultraviolet photoelectron spectrometer for high-resolution studies of molecular structure
Authors: Dromey RG , Peel JB
Published: December 2006

A high-resolution
photoelectron spectrometer incorporating a He I 58.4- nm photon source has been
constructed. A 127� 17? cylindrical electrostatic analyser of 10 cm mean radius
is used for electron energy analysis. A description is given of the interfacing
of the spectrometer to a PDP-9 computer. An on-line configuration has been
developed to enable pulse counting, signal averaging, and digitization of
spectra.
Electronic aspects of fungicidal activity in transition metal dithiocarbamate complexes
Authors: Golding RM , Lehtonen K , Ralph BJ
Published: December 2006

In this study of the
fungicidal activity of a series of transition metal ion dithiocarbamates in
relation to their electronic structure, a model is presented to interpret the biological
activity of these complexes, namely the ability of the complex to fit into a
receptor site and its ability to undergo reversible redox reactions at suitable
potentials. It is shown that in the case of the iron(III) dithiocarbamate
complexes these properties are manifested in the spin state of the iron ion.
The hydrazinolysis of heterocyclic compounds. II. 6-Amino-4-hydroxy-1-methylpyrimidine-2(1H)-thione and related compounds
Authors: Dickinson RG , Jacobsen NW
Published: December 2006

The reaction of
6-amino-4-hydroxy-1-methylpyrimidine-2(1H)-thione (3) with hydrazine is shown
to follow at least three pathways to give 4-
amino-5-hydrazino-1,2,4-triazole-3-thiol (1), 5-hydrazino-pyrazol-3- ol(5; R = NH2), (4-amino-5-mercapto-1,2,4-triazol-3-yl)acetohydrazide
(4) and triamino-guanidine (6). Similarly,
4,6-dihydroxy-1- methylpyrimidine-2(1H)-thione (18) yields (1) and malonyl dihydrazide (19), and (4). By contrast
4,6-diamino-1-methylpyrimidine-2(1H)-thione (21) does not follow any of these
pathways. Formation of (4) represents a new type of ring transformation of
pyrimidines. Mechanisms of the reactions are discussed.
The amidomethylation of some N,N-dialkylanilines (Tscherniac-Einhorn reaction)
Authors: Gale DJ , Wilshire JFK
Published: December 2006

The reaction of some
representative N,N-dialkylanilines with N- hydroxymethylphthalimide in concentrated
sulphuric acid solution (the Tscherniac-Einhorn
reaction) has been studied and the structures of the resultant phthalimide
derivatives elucidated (principally by means of p.m.r.
spectroscopy). In some instances, when two equivalents of the reagent were
used, the in corporation of two phthalimidomethyl groups into the
N,N-dialkylaniline molecule was achieved. Similar results were obtained when
the less reactive N-hydroxymethylchloroacetamide was
used as the amidomethylating reagent.
The sorption of copper species by clays. I. Kaolinite
Authors: Farrah H , Pickering WF
Published: December 2006

The effect of changes in pH
and the presence of ligands on the uptake of copper ions by kaolin has been
investigated. In alkaline media the clay suspension acts as a nucleation centre
for hydroxy-bridged copper species, and the major role of many ligands is to
'mask' this precipitation reaction. Uncharged and negatively charged complex
species are not sorbed to any measurable extent. In
acidic media, the adsorption capacity of the clay for cationic species
increases with pH. Probable mechanisms are discussed and the feasibility of
predicting the effects of ligands on sorption considered.
Potential wool growth inhibitors. Improved syntheses of mimosine and related 4(1H)-Pyridones
Authors: Harris RLN
Published: December 2006

Improved syntheses for DL-u-amino-β-(3-hydroxy-4-oxo-1,4-dihydro-l-pyridyl)propionic acid (DL- mimosine) and
related 3-hydroxy-4(1H)-pyridones are described. The
condensation of α, β -diamino- propionic acid with 4-pyrones involves preferential
reaction at the β-amino group at pH > 12, obviating the necessity to
mask the α-amino function during the syntheses.
The thermal decomposition of ethyl chloroformate
Authors: Johnson RL , Stimson VR
Published: December 2006

Elimination of ethylene
from ethyl chloroformate at 286-353� follows the rate
equation:

ke = 1012,64exp(-183600/8.314T) S-1

and is homogeneous and
molecular. We consider the production of ethyl chloride to be heterogeneous.
Chemistry of the Group IB metals. IX. Preparation of a complex containing a copper-molybdenum bond
Authors: Salah OMA , Bruce MI
Published: December 2006

The reaction between
Cu(CO)[HB(pz)3] and MoH2(C5H5)2
affords (C5H5)2Mo(H)2Cu[HB(pz)3], containing a Cu-Mo bond.
Some 3-halogenopyridazines
Authors: Barlin GB , Yap CY
Published: December 2006

Synthetic routes to some
hitherto inaccessible 3-halogenopyridazines are described. These include 3-fluoro-6-methyl-
and 3-iodo-pyridazines; methyl 3-fluoro-, 3-bromo- and
3-iodo-pyridazine-6-carboxylate; and some intermediates.
Lichens and fungi. XV. Revised structures for hopane triterpenoids isolated from the lichen Pseudocyphellaria mougeotiana
Authors: Corbett RE , Wilkins AL
Published: December 2006

The hopane triterpenoid in
the extractives from P. mougeotiana, reported in Part
VII1 of this series as hopane-6α,7α,22-triol, is now shown
to be hopane-6α,7β,22-triol (1j). There is a consequential revision
of the two triol diacetate structures to hopane-6α,7β,22-triol
7-acetate (1i) and hopane-6α,7β,22-trio1 7-acetate (1h). In addition
the diol reported as hopane-11β,22-diol has now been shown to be a mixture
of hopane-7β,22-diol (1b) and hopane-15α,22-diol (1e). Hopane-
7β,22-diol 7-acetate (1f) and hopane-15α,22-diol 15-acetate (1g) have
also been identified in the extractives.
Relative Reactivities of Various Sulfides, Selenides and Halides Towards SH2 Attack by Tributyltin Radicals
Authors: Beckwith ALJ , Pigou PE
Published: December 2006

The order of reactivity towards SH2 attack by tributyltin radicals on various groups X in four different molecular environments (RCO2CH2X, RCH2OCH2X, XCH2CO2Et and RCH2X) has been found by competition experiments to be Br > PhSe > Cl > p-CNC6H4S > PhS > p-MeC6H4S > MeS . The mechanism of the reaction of chloromethyl phenyl sulfide with alkoxides is discussed.
Heavy-Metal Complexes With (2-Chlorophenoxy)acetic Acid: The Crystal Structures of Polymeric Mercury(II) (2-Chlorophenoxy)acetate and the Thallium(I) (2-Chlorophenoxy)acetate(2-Chlorophenoxy)acetic Acid Adduct
Authors: Mak TCW , Yip WH , Kennard CHL , Smith G
Published: December 2006

The crystal structures of the mercury(II) and thallium(I) complexes with (2-chlorophenoxy)acetic acid have been determined by X-ray diffraction, and refined to residual values R 0.040 and 0.060 for 1130 and 1612 observed reflections respectively. catena-[ Bis {(2- chlorophenoxy ) acetato }mercury(II)] is monoclinic, space group Cc with Z 4 in a cell of dimensions a 25.449(7), b 7.335(2), c 10.154(1) Ǻ, β 112.83(2)°. Mercury is bonded linearly to two carboxylate oxygens [Hg-O, 2.02(1), 2.04(1)Ǻ; O-Hg-O, 175.5(6)°] and forms a polymer link to a third oxygen [Hg-O, 2.60(2)Ǻ; O-Hg-O, 88.8(6), 87.6(7)°] giving triangular coordination about the mercury. The complex adduct {(2-chlorophenoxy) acetato }thallium(I)-(2-chlorophenoxy)acetic acid is monoclinic, space group C2/c with a 27.97(1), b 4.798(1), c 13.389(6) Ǻ, β 94.23(3)° and Z 4. This is an example of an ML.LH compound, having twofold rotational symmetry with the acid proton not located. The Tl -O bonds to each ligand molecule are 2.826(7)Ǻ with two longer bonds to adjacent carboxylate oxygens [3.002(7)Ǻ] completing a distorted square-planar stereochemistry about thallium. This results in a linear polymer structure.
Structural and Stereochemical Studies on Brominated Meroterpenoids From the Dictyoceratid Sponge Cacospongia sp.
Authors: Bali DKL , Liokas V , Garson MJ , Faulkner DJ
Published: December 2006

The structures of seven minor metabolites, (5)-(11), from the encrusting sponge Cacospongia sp. Were deduced by 1H, 13C and mass spectrometric data. Compounds (5)-(7) are hydroxy derivatives of the previously isolated tribromocacoxanthene (1); their relative stereochemistry was determined from 1H-1H coupling information. Compounds (8)-(11) represent an alternative cyclization mode of a cyclocymopol-related precursor (15) and possess a spiro-fused bicyclic ring system; the relative stereochemistry of (8)-(10) was deduced by 1H n.O.e. difference spectroscopy. The biological role of brominated meroterpenoids in Cacospongia sp. is discussed.
Septanose Carbohydrates. III. Oxidation-Reduction Products From 1,2-3,4-Di-O-isopropylidene-α-D-glucoseptanose: Preparation of L-Idose Derivatives
Authors: Driver GE , Stevens JD
Published: December 2006

Oxidation of 1,2:3,4-di-O-isopropylidene-α-D-glucoseptanose (1a) with dimethyl sulfoxide and acetic anhydride has yielded methylthiomethyl ether (1b), ketone (2), and a novel product (3). Reduction of (2) gave (1a) and its L-ido isomer (4a) which yielded the mono-O-isopropylidene compound (5a) on aqueous acid hydrolysis. Treatment of (5a) with acidified acetone gave (4a) and 1,2:4,5-di-O-isopropylidene-β-L- idoseptanose (7a). Reaction of (2) with methylmagnesium iodide yielded the two 5-C-methyl compounds (8) and (9). Hydrolysis of (8) and (9) gave 5-C-methyl-D-glucose (10) and 5-C-methyl-L-idose (11), respectively, as crystalline compounds which yielded crystalline pentaacetates on acetylation. Treatment of the p-toluenesulfonate (1c) with lithium benzoate in dimethylformamide gave the benzoate of (4a) and an elimination product (17). Reaction of (1c) with sodium methoxide in methanol yielded (17) and the isomeric elimination product (18).
β-Cyclodextrin Inclusion of Adamantane Derivatives in Solution
Authors: Palepu R , Reinsborough VC
Published: December 2006

The binding constants for β- cyclodextrin inclusion in aqueous solution of a few simple adamantane salts have been determined by a conductimetric technique at 25°C over the pH range 4-10. Binding was largely dictated by the closeness of fit of the adamantyl moiety within the β- cyclodextrin cavity with the charge on the substituent group playing a minor role. The strongest binding occurred when the charge was neutralized by protonation or deprotonation.
Synthesis of Cyclopropyl Amino Acid Derivatives
Authors: Easton CJ , Tan EW , Ward CM
Published: December 2006

Derivatives of α,β-methanovaline, α,β-methanophenylalanine and β-methyl-αβmethanoalanine have been prepared by regioselective side-chain functionalization of suitably protected amino acid derivatives, followed by cyclization with either sodium hydride or 1,8-diazabicyclo[5.4.O]undec-7-ene. The approach used in this work illustrates a method for the synthesis of cyclopropyl amino acid derivatives which is complementary to existing procedures.
On the Reaction of Thiochroman-4-one and 3-(Hydroxymethylene)thiochroman-4-one With N-Chlorosuccinimide
Authors: Giles PR , Marson CM
Published: December 2006

Treatment of 3-(hydroxymethy1ene)thiochroman-4-one (4) with N-chlorosuccinimide afforded efficient routes to 3-chlorothiochroman-4-one (5), 3-chlorothiochromone (6) and 2,3-dichlorothiochromone (7). Contrary to an earlier report, 3-formylthiochromone was not obtained from this reaction. The products obtained are rationalized in terms of C-chlorination, in contrast to the action of N-chlorosuccinimide on thiochroman-4one (1), for which S-chlorination is postulated.
Enhancing the utility of science: exploring the linkages between a science provider and their end-users in New Zealand
Authors: Kelly T. , Reid J. , Valentine I.
Published: December 2006

Increasingly, publicly funded research is being required to demonstrate its contribution to the public good. In response to this trend, a science provider of soil quality research in New Zealand initiated a research project that set out to identify and characterise its end-users in order to improve the utility of their research. The researchers recognised the complex nature of this problem and adopted an action research approach based on soft systems methodology (SSM). The research process entailed 4 action research cycles, allowing greater levels of problem redefinition and participant learning. The quality of linkages between the science provider and their end-users was found to be crucial for improving the utility of that science, and is determined by: (i) the nature of the personal relationships between them, (ii) how the information meets the needs of the end-users, (iii) the end-users’ perceptions of the science provider, and (iv) the culture and structure of the end-user organisations.
Understanding and promoting adoption of conservation practices by rural landholders
Authors: Pannell D. J. , Marshall G. R. , Barr N. , Curtis A. , Vanclay F. , Wilkinson R.
Published: December 2006

Research on the adoption of rural innovations is reviewed and interpreted through a cross-disciplinary lens to provide practical guidance for research, extension and policy relating to conservation practices. Adoption of innovations by landholders is presented as a dynamic learning process. Adoption depends on a range of personal, social, cultural and economic factors, as well as on characteristics of the innovation itself. Adoption occurs when the landholder perceives that the innovation in question will enhance the achievement of their personal goals. A range of goals is identifiable among landholders, including economic, social and environmental goals. Innovations are more likely to be adopted when they have a high ‘relative advantage’ (perceived superiority to the idea or practice that it supersedes), and when they are readily trialable (easy to test and learn about before adoption). Non-adoption or low adoption of a number of conservation practices is readily explicable in terms of their failure to provide a relative advantage (particularly in economic terms) or a range of difficulties that landholders may have in trialing them.
Distribution of aromatase activity in brain and peripheral tissues of male sheep: effect of nutrition
Authors: Sharma T. P. , Blache D. , Roselli C. E. , Martin G. B.
Published: December 2006

Conversion of testosterone to oestradiol plays a major role in the feedback inhibition of gonadotrophin secretion in male sheep but little is known of the distribution or control of aromatase activity among central and peripheral tissues. Changes in activity at those sites may mediate alterations in the effectiveness of negative feedback following, for example, a change in nutrition. Using a tritiated-water assay, we quantified aromatase in several tissues in mature male sheep, assessed their contribution to oestradiol production, and tested whether activity at each site was affected by a nutritional treatment that stimulates gonadotrophin secretion. Among the brain tissues, the preoptic area had the highest concentration of activity, followed by the hypothalamus, amygdala and cortex. Among the peripheral tissues, liver and testis had the highest activity and, due to their mass, they are the major sources of circulating oestradiol. Pituitary, muscle, kidney and adipose tissues had very low aromatase levels. The nutritional stimulus increased activity in testis but not in liver or brain. We conclude that changes in aromatase activity do not mediate the effects of nutrition on steroid feedback, but aromatisation in testis, liver and brain is important in the endocrine regulation of reproduction in the mature ram.
Cloned horse pregnancies produced using adult cumulus cells
Authors: Vanderwall Dirk K. , Woods Gordon L. , Aston Kenneth I. , Bunch Thomas D. , Li Guanpeng , Meerdo Lora N. , White Kenneth L.
Published: December 2006

The objectives of the present study were to: (1) clone horses using adult cumulus cells; and (2) determine whether the cumulus cell donor affected the outcome. In vivo-matured cumulus–oocyte complexes were obtained using transvaginal ultrasound-guided follicle aspiration; oocytes were used as cytoplasts, whereas cumulus cells (from one of three different mares) were used as donor cells. Immediately following nuclear transfer and activation procedures, cloned embryos were transferred surgically to the oviduct of recipient mares (n = 2–5 embryos per recipient) that had ovulated within 24 h prior to the transfer. An initial pregnancy examination was performed between Days 14 and 16 (Day 0 = surgery); subsequent examinations were then performed every 7–10 days. A total of 136 follicles were aspirated in 96 mares, from which 72 oocytes were recovered (53%). Sixty-two cloned embryos were transferred to recipient mares, which resulted in seven (11.3%) ultrasonographically detectable conceptuses between Days 14 and 16. All seven conceptuses were lost spontaneously between Days 16 and 80. Cumulus cells from Mare 160 tended (P = 0.08) to result in a higher embryo survival rate than cumulus cells from Mare 221 (4/17 v. 1/25 respectively). To our knowledge, this is the first report documenting the establishment of cloned equine pregnancies derived from adult cumulus cells.
Role of the mitochondrial genome in assisted reproductive technologies and embryonic stem cell-based therapeutic cloning
Authors: Brenner Carol A. , Kubisch H. Michael , Pierce Kenneth E.
Published: December 2006

Mitochondria play a pivotal role in cellular metabolism and are important determinants of embryonic development. Mitochondrial function and biogenesis rely on an intricate coordination of regulation and expression of nuclear and mitochondrial genes. For example, several nucleus-derived transcription factors, such as mitochondrial transcription factor A, are required for mitochondrial DNA replication. Mitochondrial inheritance is strictly maternal while paternally-derived mitochondria are selectively eliminated during early embryonic cell divisions. However, there are reports from animals as well as human patients that paternal mitochondria can occasionally escape elimination, which in some cases has led to severe pathologies. The resulting existence of different mitochondrial genomes within the same cell has been termed mitochondrial heteroplasmy. The increasing use of invasive techniques in assisted reproduction in humans has raised concerns that one of the outcomes of such techniques is an increase in the incidence of mitochondrial heteroplasmy. Indeed, there is evidence that heteroplasmy is a direct consequence of ooplasm transfer, a technique that was used to ‘rescue’ oocytes from older women by injecting ooplasm from young oocytes. Mitochondria from donor and recipient were found in varying proportions in resulting children. Heteroplasmy is also a byproduct of nuclear transfer, as has been shown in studies on cloned sheep, cattle and monkeys. As therapeutic cloning will depend on nuclear transfer into oocytes and the subsequent generation of embryonic stem cells from resulting blastocysts, the prospect of mitochondrial heteroplasmy and its potential problems necessitate further studies in this area.
Mammalian diversity: gametes, embryos and reproduction
Authors: Behringer Richard R. , Eakin Guy S. , Renfree Marilyn B.
Published: December 2006

The class Mammalia is composed of approximately 4800 extant species. These mammalian species are divided into three subclasses that include the monotremes, marsupials and eutherians. Monotremes are remarkable because these mammals are born from eggs laid outside of the mother’s body. Marsupial mammals have relatively short gestation periods and give birth to highly altricial young that continue a significant amount of ‘fetal’ development after birth, supported by a highly sophisticated lactation. Less than 10% of mammalian species are monotremes or marsupials, so the great majority of mammals are grouped into the subclass Eutheria, including mouse and human. Mammals exhibit great variety in morphology, physiology and reproduction. In the present article, we highlight some of this remarkable diversity relative to the mouse, one of the most widely used mammalian model organisms, and human. This diversity creates challenges and opportunities for gamete and embryo collection, culture and transfer technologies.
Habitat utilisation by small mammals in a coastal heathland exhibiting symptoms of Phytophthora cinnamomi infestation
Authors: Laidlaw W. Scott , Wilson Barbara A.
Published: December 2006

Phytophthora cinnamomi is a soil-inhabiting ‘water mould’ that is pathogenic to many native plant species in Australia, and has been shown to alter plant species abundance and richness, as well as the structure of vegetation in sclerophyllous vegetation. This study investigated the effects of P. cinnamomi-induced vegetation disturbance and habitat degradation on microhabitat associations of small mammals in a coastal heathland in southern Australia. Seven small mammal species were trapped in a P. cinnamomi-infested heathland community over four years. Trap stations were classified into three disease classes (non-diseased, active disease and post-disease) and structural and floristic aspects of the vegetation were recorded at each station. The mean number of species captured was greatest in non-diseased areas and least in post-disease areas. The total capture frequency of small mammals was lower in post-disease areas except where they were covered by thick stands of tall tea-tree (Leptospermum sp.). Combined small mammal captures were associated with thick vegetation and floristic factors. Captures of Antechinus agilis, Rattus fuscipes, Rattus lutreolus and Sminthopsis leucopus were greatest in non-diseased vegetation and were less frequent in areas of diseased vegetation. A. agilis and R. fuscipes captures were correlated with a floristic factor associated with non-diseased vegetation, while R. lutreolus was associated with structural factors, preferring thick vegetation. The impact on Cercartetus nanus and Isoodon obesulus could not be assessed owing to low captures of these species. Modification of vegetation structure and floristics associated with P. cinnamomi infestation is having a significant impact on the habitat utilised by the small mammal communities in the area. This impact highlights the need to identify and protect those areas that remain free of P. cinnamomi infestation. Continued spread of the pathogen will reduce the area of suitable small-mammal habitat able to support the diverse communities of the eastern Otway Ranges, Victoria, Australia.
Dietary preferences of juvenile green turtles (Chelonia mydas) on a tropical reef flat
Authors: Fuentes Mariana M. P. B. , Lawler Ivan R. , Gyuris Emma
Published: December 2006

We offer the first published description of the feeding choices made by juvenile green turtles on a tropical feeding ground, in this case a reef flat environment. We collected 85 lavage samples from 76 turtles and compared the food eaten to the food resources available. Resampling of some individuals enabled us to gain preliminary insights into diet switching by juvenile turtles. The area of the reef flat at Green Island, Queensland, Australia, had similar proportions of coverage by seagrasses (52%) and by algae (48%). Seven species of seagrass and at least 26 species of algae were identified. The dominant seagrasses, on an area basis, were Cymodocea sp. (29.7%), Halodule sp. (11.1%), Thalassia sp. (6.4%) and Syringodium sp. (4.5%). The most dominant algae were Halimeda spp. (10.2%). and Galaxaura sp. (7.25%). Most juvenile green turtles ate primarily seagrass, but some individuals ate predominantly algae. The turtles showed clear preferences for the seagrass Thalassia hemprichii and the algae Gracilaria spp., Gelidiella sp., Hypnea spp. despite their low abundance in many cases. Ways to improve our understanding of preferences and possible diet switching, and potential factors affecting them, are discussed.