bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization and development of rotational behavior in Helisoma embryos: Role of endogenous serotonin
Authors: Diefenbach Thomas J. , Koehncke Niels K. , Goldberg Jeffrey I.
Published: May 2005

Cilia‐driven rotational behavior displayed by embryos of the pond snail Helisoma trivolvis was characterized in terms of its behavioral subcomponents, developmental changes, and response to exogenous serotonin. Rotation was found to be a complex behavior characterized by four parameters; rotational direction, rotation rate, rotational surges, and periods of inactivity. These parameters all exhibited characteristic developmental changes from embryonic stage E15 through stage E30. Notably, both rotation rate and frequency of rotational surges increased from stage E15 to E25 and declined to an intermediate level by stage E30. It appeared that the developmental increase in overall rotation rate was caused primarily by an increase in surge frequency, rather than an increase in the rate of nonsurge rotation. Immersion of embryos inserotonin‐containing pond water resulted in a dose‐dependent, reversible increase in rotation rate as well as a dose‐dependent, reversible decrease in surge frequency. The serotonin antagonist, mianserin, abolished the excitatory effect of exogenous serotonin. Furthermore, application of mianserin alone reduced rotation rate and virtually abolished rotational surges. Taken together, these pharmacological results suggest that endogenous serotonin is responsible for generating rotational surges. Given that early embryos contain only a single pair of serotonergic neurons (Goldberg and Kater, 1989) during the stages when rotational surges are expressed, these results also prompt the hypothesis that these neurons, embryonic neurons C1, act as cilioexcitatory motor neurons during embryonic development.
Nitric oxide and carbon monoxide as possible retrograde messengers in hgippocampal long‐term potentiation
Authors: Hawkins R. D. , Zhuo M. , Arancio O.
Published: May 2005

We have been investigating the hypothesis that the membrane‐permeant molecules nitric oxide (NO) and carbon monoxide(CO) may act as retrograde messengers during long‐term potentiation (LTP). Inhibitors of either NO synthase or heme oxygenase, the enzyme that produces CO, blocked induction of LTP in the CA1 region of hippocampal slices. Brief application of either NO or CO to slices produced a rapid and long‐lasting increase in the size of synaptic potentials if, and only if, the application occurred at the same time as weak tetanic stimulation of the presynaptic fibers. The long‐term enhancement by NO or CO was spatially restricted to synapses from active presynaptic fibers and appeared to involve mechanisms utilized by LTP, occluding the subsequent induction of LTP by strong tetanic stimulation. The enhancement by No or CO was not blocked by the NMDA receptor blocker APV, suggesting that NO and CO act downstream for the NMDA receptor. In other systems, both NO and CO produce many of their effects by activation of soluble guanylyl cyclase nd cGMP‐dependent protein kinase. An inhibitor of soluble guabylyl cyclase blocked the induction of normal LTP. Conversely, membrane‐permeabel analog 8‐Br‐cGMP produced a rapid onset and long‐lasting synaptic enhancement if, and only if, it was applied at the same time as weak presynaptic stimulation. Similarly, two inhibitors of cGMP‐dependent protein kinase blocked the induction of normal LTP, and a selective activator of cGMP‐dependent protein kinase produced activity‐dependent long‐lasting synaptic enhancement. 8‐Br‐cGMP also produced and activity‐dependent, long‐lasting increase in the amplitude of evoked synaptic current between pairs of hippocampal neurons in dissociated cell culture. In addition, 8‐Br‐cGMP, like NO, produced a long‐lasting increase in the frequency of spontaneous miniature synaptic currents. These results are consistent with the hypothesis that NO and CO, either alone or in combination, serve as retrograde messengers that produce activity‐dependent presynaptic enhancement, perhaps by stimulating soluble guanbylyl cyclase and cGMP‐dependent protein kinase, during LTP in hippocampus. 1994 John Wiley & Sons, Inc.
The negative ion mass spectra of mixtures of sulphur and organic compounds. II—the formation of [C5H5 + Sn]− from the mixture of sulphur and ferrocene
Authors: Hirata Yukio , Matsumoto Kozo , Takeuchi Tsugio
Published: May 2005

The negative ion mass spectra of ferrocene and of a mixture of ferrocene with sulphur were studied. In the spectrum of the mixture, characteristic peaks of [C5H5 + Sn]− (n = 1, 2, 3 etc.) were observed. The structures of these ions are discussed.
Mass spectrometry of some triphenylcyclopropenium salts. Competition between dimerisation and adduct formation
Authors: Györösi Peter , Hvistendahl Georg , Undheim Kjell
Published: May 2005

The triphenylcyclopropenium chloride, bromide and iodide evaporate in the mass spectrometer mainly as the covalent cation‐halide adduct, the fluoroborate as the corresponding fluoride adduct and boron trifluoride. In addition di‐3,3′‐triphenylcyclopropene is formed, presumably via triphenylcyclopropenyl radicals.
Dual mechanisms for the fragmentation of 1‐benzoylbenzotriazole upon electron impact
Authors: Yamada Shuzo , Kamiyama Yojiro , Ohashi Mamoru
Published: May 2005

The electron impact induced fragmentation of 1‐benzoylbenzotriazole has been studied by 13C labelling experiments. It has been found that the loss of CO from the [M  N2]+˙ ions proceeds by two routes; about 78% of the ions decompose via the molecular ions of the corresponding thermal fragmentation product, 2‐phenylbenzoxazole, and 22% via those of the corresponding photochemical fragmentation product, 6‐phenanthridone.
Mass spectral rearrangements of N,N‐bis(4′‐arylthio‐2′‐butynyl)anilines and N,N‐bis(4′‐arylsulfonyl‐2′‐butynyl)anilines
Authors: Thyagarajan B. S. , Glaspy Phillip E. , Brown Peter
Published: May 2005

The title compounds display unusual modes of fragmentation under electron impact. One of the dominant modes is the concerted elimination of the two arylthio and arylsulfonyl moieties followed by further extrusion of the C6H4 unit as a cumulene. No elimination of SO2 is observed from any of the sulfones nor an expulsion of the C4H4 fragment. Such behavior contrasts strikingly with that of 1,4‐diarylsulfonyl‐2‐butynes and of the 1,6‐diarylsulfonyl‐2,4‐hexadiynes.
Fast atom bombardment mass spectra of involatile monophosphonated and mixed sulphonated/monophosphonated azo dyestuffs
Authors: Monaghan John J. , Barber Michael , Bordoli Robert S. , Sedgwick R. Donald , Tyler Andrew N.
Published: May 2005

Fast atom bombardment mass spectra of a range of involatile monophosphonated and mixed sulphonated/monophosphonated azo dyestuffs are presented. Good spectra are obtained and the fragmentations are discussed with special reference to the ions formed by cleavage of the azo linkage. The negative ion spectra are shown to be superior in terms of signal to background and structural information to those obtained in the positive ion mode. The results are compared with those obtained from sulphonated azo dyestuffs.
Photodissociation of gaseous [C4H5N]+˙ ions
Authors: Weger E. , Brand W. A. , Levsen K.
Published: May 2005

The photodissociation of [C4H5N]+˙ ions generated by ionization of pyrrole (1), allyl cyanide (2), crotonitrile (3), cyclopropyl cyanide (4) and methacrylonitrile (5) has been studied using ion beam techniques. At least four different stable ion structures have been distinguished, which is in contrast to earlier CAD studies. In addition it has been shown that [C2H3N]+˙ fragment ions formed by dissociative ionization of the same precursors have structures which are distinct from that of ionized acetonitrile.
Mass spectra of 17ξ‐hydroxy‐5ξ‐androstane C(3) ketone and C(3ξ) alcohol isomers
Authors: Jackson Chung‐Ja Choi , Templeton John F. , Reimer Mark L. J. , Westmore John B.
Published: May 2005

Positive ion electron impact mass spectral data for the four isomeric 17ξ‐hydroxy‐17ξ‐methyl‐5ξ‐androstane C(3) ketones and the eight isomeric C(3ξ) alcohols are reported. In contrast to earlier reports, no general correlation was observed between the [MH2O]+˙/[M]+˙ ratio and the configuration at C(17). The ratios of the intensity of several fragment ions to that of the molecular ion do differentiate between the 5α‐ and 5β‐isomers in both C(3) ketones and alcohols, the extent of fragmentation being greater for 5β‐steroids. All of these fragments probably involve elimination of a water molecule at some stage in their formation. Elimination of water is also enhanced for 3α‐ v. 3β‐hydroxysteroids, particularly in a 5β‐isomer.
The question of cyclic versus acyclic ions: The structure of [C10H12]+˙ gas phase ions
Authors: Dass Chhabil , Gross Michael L.
Published: May 2005

The extent of isomerization of acyclic and cyclic gas phase radical cations of composition [C10H12]+˙ has been investigated by using collisionally activated dissociation spectroscopy. Both electron and charge exchange ionizaiton were employed to form the ions with various internal energies. The [C10H12]+˙ ions investigated consisted of ionized phenylbutenes, ring‐substituted methyl derivatives of allylbenzene and phenylpropene, 1‐methyl‐2‐isopropenylbenzene, benzylcyclopropane, phenylcyclobutane, tetralin and 1‐methylindan. The 1‐methylindan and tetralin radical cations are the most stable of the C10H12 isomeric radical ions. The [C10H12]+˙ formed from acyclic olefins having the double bond in conjugation with the aromatic ring retain the initial structure to a significant extent. However, ions derived from olefins with the double bond out of conjugation with the benzene ring preferentially cyclize to stable five‐ and six‐membered cyclic ions. Ring opening of small‐ring cyclic ions, such as ionized benzylcyclopropane and phenylcyclobutane, occurs, followed by ring closure to the tetralin radical cation.
Adduct ion formation by metal complexes under methane negative chemical ionization conditions
Authors: Dillow G. W. , Gregor I. K. , Guilhaus M.
Published: May 2005

Negative chemical ionization mass spectrometry is used as a probe to examine reactions between hydrocarbon radicals and metal complexes in the gas phase. The methane negative chemical ionization mass spectra of 27 complexes of cobalt(II), nickel(II) and copper(II) in the presence of O4, O2N2 and N4 donor atom sets are characterized by two dominant series of adduct ions of the form [M + CnH2n]− and [M + CnH2n+1]− at m/z values above the molecular ion, [M]−. Insertion of the CH radical into the ligand followed by radical/radical recombination and electron capture is proposed as the major mechanism leading to the formation of [M + CnH2n]− adduct ions. A second pathway involves ligand substitution by CnH2n+1 radicals concomitant with H elimination and electron capture. Oxidative addition at the metal followed by ionization is suggested as the principal pathway for the formation of [M + CnH2n+1]− adduct ions.
Does the dieckmann condensation occur in the gas phase?
Authors: Raftery Mark J. , Bowie John H.
Published: May 2005

Burinsky and Cooks1 have reported that deprotonated dimethyl adipate eliminates methanol via a gas‐phase Dieckmann condensation. This is in contrast to the behaviour of simple methyl ester enolates which lose MeOH by a different mechanism, e.g. MeOCOC̄HCH2R → [MeO(OCCHCH2R)] → OCCHC̄HR + MeOH. Evidence is presented which supports the Dieckmann mechanism for adipates. For example, MeOCOC̄(Me)CH2CH2CD(Me)CO2Me should eliminate MeOD in a Dieckmann condensation, but MeOH by the alternative mechanism outlined above. Experimentally, MeOD is lost exclusively. Similarly, MeOCOC̄DCH2CH2C(Me)2CO2Me also loses MeOD, consistent with a Dieckmann process.
Ring opening of the molecular ion of 5(4H)‐oxazolone
Authors: Császár Attila G. , Somogyi Árpád , Pócsfalvi Gabriella , Traldi Pietro
Published: May 2005

Quantum chemical calculations were carried out at several theoretical levels (semi‐empirical, MNDO; ab initio, 3–21G SCF, 6–311G** SCF and DZP CISD) to investigate the ring‐opening process of and the loss of CO from the molecular ion of 5(4H)‐oxazolone. The ring‐opening process is predicted to be slightly endothermic and the loss of CO from the open‐ring molecular ion to be slightly exothermic. Detailed population analysis calculations suggest the weakening of the lactonic CO bond in the closed‐ring molecular ion and weak carbon—carbon and nitrogen—(formy)—carbon bonds in the open form. Both the open‐ring molecular ion and the [M–CO]+· ion are suggested to be of distonic type.
The viscoelastic behavior of the principal compliance matrix of a unidirectional graphite/epoxy composite
Authors: Morris D. H. , Brinson H. F. , Yeow Y. T.
Published: May 2005

A testing program was conducted to determine the time‐temperature response of the principal compliances of a unidirectional graphite/epoxy composite. It is shown that two components of the compliance matrix are time and temperature independent. In addition, the compliance matrix is found to be symmetric for the viscoelastic composite. The time‐temperature superposition principle is used to determine shift factors. It is shown that shift factors are independent of fiber orientation for fiber angles that vary from 10 to 90° with respect to the load direction.
Improved epoxy‐amine matrices for composites
Authors: McLean P. D. , Garton A. , Stevenson W. T. K. , Macphee K. E.
Published: May 2005

The physical and mechanical properties of epoxy‐amine matrices can be improved by the use of additives known as epoxy fortifiers. The tensile strength of a typical aminecured epoxy increased from 82 MPa to 123 MPa, the tensile modulus form 2.5 GPa to 4.1 GPa, and the tensile test specimens also failed in a ductile fashion. The improvements in matrix properties translated into improved performance for filament‐wound and cloth‐reinforced composites. For example, the transverse moduli and compression strengths of carbon fiber/epoxy filament‐wound tubes and plates increased at least 20 percent with the addition of fortifiers, while the compression strength of glass cloth/epoxy laminates increased by up to 41 percent.
Blends containing liquid crystalline polymers: Preparation and properties of melt‐drawn fibers, unidirectional prepregs, and composite laminates
Authors: Dutta D. , Weiss R. A. , Kristal K.
Published: May 2005

This paper discusses the effect of melt drawing on the mechanical properties and morphology of liquid crystalline polymer (LCP) and thermoplastic polymer blends. Extruded fibers and films of LCP/polymer blends were melt drawn to develop uniaxial orientation of the dispersed LCP phase. The longitudinal modulus increased with increasing draw. The increase in modulus was due to higher aspect ratio of the LCP fibrils and improved molecular orientation of the LCP chains within the fibrils. Laminated composites were prepared using the extruded sheets as prepregs. The mechanical properties and the coefficient of thermal expansion (CTE) of the prepreg and the laminates agreed well with predictions from conventional composite lamination theories.
Thermodynamic behavior of solid polymers in uniaxial deformation
Authors: Lyon R. E. , Farris R. J.
Published: May 2005

The heat and work of uniaxial deformation were measured for two commercial polyurethane elastomers and a low density polyethylene using a new deformation calorimeter. Internal energy changes in the materials resulting from deformation were calculated from the difference between the heat and work according to the first law of thermodynamics. The elastomers were found to exhibit complete reversibility for small and large strain deformation cycles as determined from the absence of a permanent internal energy change, even though one of these undergoes strain‐induced crystallization and melting. The low density polyethylene behaves irreversibly even at small strains, and will store 30 percent of the deformation work as internal energy during drawing at room temperature.
Statistical entropy model for relaxation in stressed polymer glasses
Authors: Chow T. S.
Published: May 2005

The molecular kinetic theory near the glass transition, bused on the existence of free volume distribution, is extended to incorporate the effects of stress and stress rate. The fundamental equations for the volume relaxation and recovery in stressed amorphous polymers are derived in accordance with the balance of nonequilibrium statistical entropy. Using these kinetic equations, an earlier nonequilibrium criterion for the glass transition temperature, Tg, is generalized to include the effects of stress and stress rate. In contrast to the prevalent thinking toward free volume theories, an explicit expression between Tg and stress is developed and reveals that Tg does not continue to increase at all pressures but levels off to a “universal” asymptote at very high pressure (>10 K bars). The expression is applicable to any tension and compression stress conditions. A comparison between theory and experiment under constant stresses determines the activation volume tensor which reveals the molecular mechanism relating Tg and the plastic yield of glassy polymers.
A simple model of nonisothermal coextrusion
Authors: Nordberg M. E. , Winter H. H.
Published: May 2005

A numerical method has been developed that takes the streamline finite difference method for modeling fully developed multilayer polymer flows and adds to it a simple means of accounting for nonisothermal conditions. In industrial practice, temperature control is often used to match material viscosities and, thereby, to avoid flow instabilities. By numerically calculating both viscosity ratios and normal stress difference ratios, the numerical method allows one to judge the relative stability of different flows and to choose an intelligent set of experiments when designing a coextrusion process. The algorithm has been successfully tested for a number of polymer melt constitutive equations in flows where the viscosity jumps no more than two orders of magnitude between fluids. Results for a rheologically well characterized polystyrene low‐density polyethylene system and for an industrially interesting high‐density polyethylene/Ultem system show that the common practice of matching zero‐shear viscosities is overly simplistic when interface shear rate, conduction, normal stress, and flow rate effects are taken into account.
Structural analysis and electrical properties of halogen substituted poly(paraphenylene)
Authors: Mertens R. , Krikor H. , Nagels P. , Callaerts R. , Remaut G.
Published: May 2005

Poly(tetrafluoro‐p‐phenylene) was prepared by the modified Ullmann reaction. The average degree of polymerization was determined from electron impact mass spectrometry and was found to be n = 8. The structure of the polymer was studied using infrared, Raman, ultraviolet absorption spectroscopy and differential scanning calorimetry. Polymerization of 1,4‐diiodo‐2,3,5,6‐tetrafluorobenzene resulted in the disappearance of the characteristic C‐I vibrations and the appearance of new absorption bands in the infrared and Raman spectra. At room temperature poly(tetrafluorophenylene) is an insulator. Attempts to increase the dc conductivity on FeCl3 and sodium doping were unsuccessful until now.
Critical review of the molecular topology of semicrystalline polymers: The origin and assessment of intercrystalline tie molecules and chain entanglements
Authors: Seguela Roland
Published: May 2005

Intercrystalline molecular connections in semicrystalline polymers have been the subject of numerous discussions and controversies. Nevertheless, there is one point of agreement: such intercrystalline tie molecules have a prime role in the mechanical and use properties of the materials, notably the resistance to slow crack growth. This article is a critical review of the mechanisms of generation of the tie molecules during the stage of crystallization and of the experimental and theoretical assessment of their concentration. Polyethylene and related materials are mainly studied. The contribution of chain entanglements is also discussed in parallel with tie molecules. Particular attention is paid to Huang and Brown's statistical approach, which appears to be the most appropriate one for predictive purposes and has aroused much interest from various authors. Attempts are made to provide solutions to the shortcomings of this model. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1729–1748, 2005
Copper‐Tungsten Shaped Charge Liner and its Jet
Authors: Tie‐Fu Wang , He‐Rong Zhu
Published: May 2005

The use of copper‐tungsten alloys for shaped charge liners leads to an improving of the jet penetrability into an homogeneous steel target. In comparison with copper jets, the penetration depth can be increased by a factor 1.3. The improving is due to the increasing of both the density and the break‐up time. Copper‐tungsten shaped charge jets and their aspect of break‐up were investigated by flash radiography. Both the effect of rotation of copper‐tungsten jets and their standoff performance were examined.
Liquid‐phase nucleation and evolution as a cause of superplasticity in alloys of the Al–Ge system
Authors: Bryukhovetsky V. V. , Kuznetsova R. I. , Zhukov N. N. , Poida V. P. , Klepikov V. F.
Published: May 2005

The kinetics of phase transformations taking place under conditions of superplastic flow in the matrix alloys of the Al–Ge system was studied. It has been found that these alloys manifest superplasticity in the nonequilibrium state that is characterized by the presence of the metastable liquid phase in their structure. It is shown that the liquid‐phase formation in the Al–Ge alloys is due to the effect of contact melting. The time of existence of the liquid phase in these alloys correlates with the time of superplastic deformation. The liquid‐phase formation is considered as a cause of superplasticity in the alloys under study. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new polymer thin film with electrical bistable states
Authors: Jiang Yiming , Wan Xinggong , Guo Feng , Xie Hengbo , Liu Ping , Li Jin
Published: May 2005

Thin film polyethylene naphthalate (PEN) with electrical bistable states at room temperature has been obtained by vacuum deposition. The grain size of the film was less than 100 nm with a roughness of a few nanometers. This film showed a good thermal stability up to 150 °C. The impedance of the film can be changed from a high‐impedance state to a conductive state when a voltage higher than 3.5 V is applied, and the transition time was less than 20 ns. This material is suitable for producing ultrahigh‐capacity memory. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measuring the junction temperature of III‐nitride light emitting diodes using electro‐luminescence shift
Authors: Cho Jaehee , Sone Cheolsoo , Park Yongjo , Yoon Euijoon
Published: May 2005

The junction temperature rise of light emitting diodes due to self‐heating effects during operation of the LED is measured using the electro‐luminescence of the band‐to‐band recombination. This method is useful for the junction temperature monitoring of small geometry devices, indirectly. The junction temperature measured in InGaN/GaN multi‐quantum well LEDs with 1 mm2 device size rises to 180 °C when the input current is 380 mA. The relationship between the junction temperature and the LED efficiency is clarified with experimental results. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, characterization and ESR measurements of CoNiO nanoparticles
Authors: Köseoğlu Y. , Yıldız F. , Slazar‐Alvarez G. , Toprak M. , Muhammed M. , Aktaş B.
Published: May 2005

Powders of cobalt core with a nickel (II) oxide shell (CoNiO) have been studied by Electron Spin Resonance (ESR) technique in the temperature range of 10–300 K. A strong and broad (1300 G) single ESR peak in X‐, K‐ and Q‐band spectra has been observed at all the temperature ranges. While the resonance field remains almost constant, both the ESR line intensity and the line width were seen to increase first slowly down to Tc = 160 K. And then both the resonance field and the ESR signal intensity decrease and the line width increase with decreasing temperature. Below Tc the intensity smoothly decrease down to 10 K. This kind of behavior is attributed to a typical spin‐glass like behavior. Some small and relatively smooth changes at about 60 K, 90 K, 210 K, and 250 K are appeared as well. A linear dependence of resonance field to microwave frequency is observed at room temperatures and the effective g‐value and internal field are theoretically found as 2,17 and 90 G, respectively. The experimental data indicate a very strong spin disorder (spin frustration) due to antiferromagnetic exchange interactions among the spins. This is attributed to the D‐M anisotropy on the particle surfaces that it is expected to enhance due to increment of surface‐to‐volume ratio. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and transport properties of coherently strained La2/3Ca1/3MnO3/SrTiO3superlattices
Authors: Lu Yafeng , Klein J. , Herbstritt F. , Philipp J. B. , Marx A. , Alff L. , Gross R. , Zhang H.
Published: May 2005

We have prepared high quality, coherently strained La2/3Ca1/3MnO3/SrTiO3superlattices with different modulation periods by laser molecular beam epitaxy on (001) SrTiO3and NdGaO3substrates. A detailed structural characterization was performed by high‐angle X‐ray diffraction (HAXRD) and low‐angle X‐ray reflectivity (LAXRR). All superlattices are very flat, show excellent structural coherence and very small mosaic spread (0.02°). The in‐plane coherency strain was varied by changing the thickness ratio of the constituent layers allowing for a systematic variation of the resulting tetragonal distortion of LCMO. Thec‐axis lattice parameter of LCMO could be continuously changed from 3.87 Å to 3.79 Å. The interface roughness was analyzed by offset low‐angle X‐ray reflectivity and low‐angle rocking curve measurements. It was found to be of the order of one unit cell with a significant part of the roughness being vertically correlated. The strain induced tetragonal distortion of LCMO was found to cause strong reduction of the paramagnetic to ferromagnetic transition temperature from about 260 to 120 K and an increase of resistivity. The transport properties in the paramagnetic regime could be well described by a small polaron hopping model. The lattice distortions were found to result in a significant increase of the polaron trapping energy. Our results show that coherently strain superlattices are an interesting model system for the systematic study of the effect of lattice distortions on the magnetic and electronic properties of the doped manganites. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure, stability and electronic properties of TiO2 nanostructures
Authors: Enyashin Andrey N. , Seifert Gotthard
Published: May 2005

The front cover of this issue depicts a view of two types of lepidocrocite‐based cylindrical nanotubes (TiO2, light grey – titanium, red – oxygen). These structures represent examples of a manifold of stable tubular forms of the titania layer modifications anatase and lepidocrocite. These structures were obtained using density‐functional based calculations and characterize the essen‐tial structural features of synthesized titania nanotubes.

Andrey Enyashin is a PhD student at the Institute of Solid State Chemistry at the Ural Branch of the Russian Academy of Sciences in Ekaterinburg. He performed this study during a visit at the Institute of Physical Chemistry and Electrochemistry (IPEC) of the TU Dresden together with Gotthard Seifert. Professor Seifert is head of the theory group at the IPEC. His research interests are in the areas of quantum chemistry, cluster physics and computational materials research.
Study of clusters by mass spectrometry
Authors: Stamatović A. S. , Maerk T. D.
Published: May 2005

A review of mass spectrometric methods used to study different kinds of clusters is presented. These methods have proved to be indispensable in the cluster field owing to their great flexibility, sensitivity and wide dynamic range. This reviews presents new mass spectrometric methods and techniques such as quadrupole analysers and RF lenses, different ion‐trap geometries, time‐of‐flight (TOF) methods including the reflectron geometry). A variety of ionization methods, both for the production of positive and negative ions, with different amounts of released excess energy, are discussed in detail. Special attention is given to different degree of post‐ionization fragmentaqtion and metastability of ions produced by the respective ionization methods. The ability to follow the metastable decay processes in rather different time‐windows is also one of the salient features of the mass spectrometric methods reviewed here, involving both classical and new geometries. Detection of very large cluster ions by conventional methods is not always effective, and alternative methods like post‐acceleration and using a conversion dynode in front of the multiplier will be included here. Moreover, mass spectrometric methods offer the possibility of producing beams of mass‐selected cluster ions necessary for the study of a whole line of process like optical spectrometry, photodetachment, photofragmentation, photoionization, electron beam ionization, and charge‐exchange processes. Examples of these processes are also discussed in this review.
An apple II based datasystem for AES depth profiling on a varian spectrometer
Authors: Hazell L. B. , Baker C. , Dearden D. P.
Published: May 2005

A description is given of an Apple II based Auger spectroscopy datasystem specifically designed for depth profiling applications. Software features which are not available on commercial systems are emphasized. In particular, the utility of peak overlap and noise threshold subtraction routines are demonstrated with reference to two examples of practical profiling.
Characterization of buried interfaces in electroplated bronze wires by SIMS
Authors: Wilhartitz P. , Grasserbauer M. , Hiesböuck H. G. , Bartl C.
Published: May 2005

SIMS was applied to characterize contaminations on concealed interfaces between bronze and lead–tin alloys. Carbon contaminations were found to cause diminished soldering properties whereas oxygen showed no influence. The existence of intermetallic phases at the interface zone was proved by measuring molecular ion signals of copper and tin. Sophisticated identification procedures allowed the interpretation of the complex high resolution mass spectra encountered at mass 60.
Oxygen adsorption on Ni3Al(001) by low‐energy ion beams
Authors: Shen Y. G. , O'Connor D. J. , MacDonald R. J.
Published: May 2005

The interaction of O with the Ni3Al(001) surface has been studied using low‐energy He+ scattering. Oxygen adsorption at an exposure of 10 L and a temperature of 700°C results in the total disappearance of the Ni ISS signal, indicating the formation of a monolayer AlOx overlayer. This oxide AlOx overlayer has been examined by measuring the azimuthal angle dependence of the scattered ion yield at fixed scattering angle under different coverages of oxygen. The azimuthal variations of the Ni and Al ISS signals from the O‐covered surface are compared with those of Ni and Al from the clean surface, and the results used to derive a value for the fractional coverage of oxygen on the surface. The analysis supports the model that the oxide initially grows in the form of islands, with no influence on remaining areas of the crystal. No evidence of the ordering of the oxide islands was observed. Further evidence of the growth of the AlOx surface. The results indicate that the remaining (uncovered) Ni3Al surface retains the crystal structure of a clean surface. The rate of growth of the AlOx islands on the Ni/3Al(001) surface was also found to be related to temperature.
Compatibility between PVC and plasticizer blends and its relation with processing
Authors: Ramos‐Devalle L. , Gonzalez‐Roa C. , Sanchez‐Adame M. , Rodriguez J. Zamora
Published: May 2005

The compatibility of suspension PVC with various plasticizer blends was determined by means of calculated compatibility predictors, such as solubility parameters and polarity parameters, as well as actual measurements of compatibility. Then, with a torque rheometer, the temperature at the fusion peak was obtained for various PVC/plasticizer blend compositions. Finally, empirical equations were derived to relate compatibility parameters with the temperature at the fusion peak, predicting the effect of plasticizer blend on processability.
Molders' perceptions of vinyl injection molding compounds
Authors: Gruber C. M. , Gockowski N. L.
Published: May 2005

As a result of advances in such properties as processability and thermal stability, vinyl may now compete with ABS and many engineering resins in a broad number of injection molding applications. However, do past experiences with PVC compounds prevent molders from quoting on new vinyl jobs? What do molders think of vinyl's physical properties and molding characteristics versus other resins? Independent research conducted in 1989 questioned a broad range of molders in the United States regarding their perception of vinyl versus other resins as an injection molding material. The results highlight the fact that molders are aware of the benefits of vinyl in finished part applications, but require training to overcome the perceptions of past molding experiences. This paper shares the results of this survey.
Vinyl bottle performance with the addition of vinyl bottle flake
Authors: Fazey Tony
Published: May 2005

The effect of adding recycled vinyl bottle flake to virgin bottle compound has been studied. Vinyl bottles contains 10 to 50% recycled vinyl bottle flake were produced on a Bekum extrusion blow molding machine. The performance properties of the vinyl bottles were evaluated, and the optimum level of recycled flake was determined.
Fluorescence yields, ωK (12 ≤ Z ≤ 42) and ω (38 ≤ Z ≤ 79), from a comparison of literature and experiments (SEM)
Authors: Hanke Wolfgang , Wernisch Johann , Pöhn Christian
Published: May 2005

A presentation of fluorescence yields, ωK and ω, in terms of dependence on Z is developed from theory, valid for x‐ray excitation by electrons, from literature data and from experiments. The results

and

are a contribution to computer‐supported quantitative x‐ray analysis.
Determination of tin in silicate rocks by energy‐dispersive X‐ray fluorescence spectrometry
Authors: Evans John R. , Jackson John C.
Published: May 2005

An accurate and precise method was developed for the determination of tin in geological materials using energydispersive x‐ray fluorescence spectrometry. Previously analyzed silicate rocks were treated as unknowns in order to evaluate statistically the precision and accuracy of the method.
Influence of non‐flat sample surface on α‐coefficients
Authors: Kuczumow A. , Helsen J. A.
Published: May 2005

The application of the Lachance‐Traill α‐correction algorithm assumes homogeneous samples with flat surfaces. In this paper a mathematical approach is presented describing the influence of non‐flatness of sample surfaces on the value of the α‐coeffficient. The calculation is performed on a surface consisting of regular prismatic or pyramidal grooves. The α‐coefficient is found to have a hyperbolic dependence on the slope of the solid with respect to the macroscopic surface.
Yeast mutants affected in viability upon starvation have a modified phospholipid composition
Authors: Desfarges L. , Durrens P. , Juguelin H. , Cassagne C. , Bonneu M. , Aigle M.
Published: May 2005

Selection of mutations, based on the suppression of rvs161Δ defects, was performed. Ten mutants were obtained, ranged amongst four complementation groups, named SUR1, SUR2, SUR3 and SUR4. All sur mutations also suppress a mutation in another gene, RVS167, indicating that all six genes are involved in the same biological pathway. The sur mutant cells have abnormal morphologies in stationary phase, i.e. dumbbell‐like in sur1, sur2 or sur3 strains and multibudded in sur4 strains. Several phenotypic characteristics of the physiological suppressors as well as the rvs161Δ strain itself led us to analyse the phospholipid composition of the mutants. The assays show an overall decrease of the phospholipid amounts and modifications in the relative contents of some phospholipid classes in sur mutant cells.
Synthesis, Structure, and Properties of [Hg6As4][YbBr6]Br, a Supramolecular Assembly Featuring a Discrete [YbBr6]3− Anion
Authors: Olenev Andrei V. , Shestimerova Tatiana A. , Schnelle Walter , Shevelkov Andrei V.
Published: May 2005

A novel supramolecular assembly [Hg6As4][YbBr6]Br has been prepared and its structure determined. It crystallizes in a cubic space group $Pa{\bar 3}$, a = 12.362(1) Å, with Z = 4. The title compound is a bi‐compartmental supramolecular architecture that is built of a three‐dimensional [Hg6As4]4+ cationic framework trapping two types of guest anions, [YbBr6]3− and Br−, in a chessboard‐like order. [Hg6As4][YbBr6]Br is a Curie‐Weiss paramagnet with a magnetic moment of 4.47 μB, which reflects the localized character of the 4f13 electrons of Yb. Thus, the whole assembly behaves as a magnetically dilute compound.
An alarming threat to the red organ pipe coral Tubipora musica and suggested solutions
Authors: Ammar Mohammed S. A.
Published: May 2005

Eighteen sites along the southern Egyptian Red Sea coastline were surveyed for the organ pipe coral Tubipora musica with reference to relative abundance of juveniles, adults, flourishing live, traces of recently collected, traces of older collected and dead colonies. The study was done using a 30‐m long graded tape, throughout the period April 2004 to October 2004. T. musica is categorized as vulnerable according to IUCN (2001) as there is an estimated population size reduction of ≥50% over the last 10 years, based on the index of abundance and the decline in area of occupancy. Sites 3 (1 km south Dorry) and 5 (Northern Sharm El‐Fokairy), having the highest traces of recently collected Tubipora, are characterized by a lot of fishing activity as well as being near the shore, indicating insufficient shore patrolling. Flourishing live Tubipora colonies were found in considerable amounts in Wadi El Mahara, probably because of the very strong waves breaking on the reef crest, the zone containing the Tubipora colonies, making it difficult to access for collection. Juveniles of T. musica were found to be flourishing and attaching to rocks, dead corals and rubble on the reef crest of Wadi El Mahara, an observation that can be used in farming and rehabilitating other reefs denuded of the species.
Adolescent dating experiences described by Latino college students
Authors: Raffaelli Marcela
Published: May 2005

Latino college students (M age=21.4 years) completed self‐report surveys assessing adolescent dating experiences. Compared to young men (), young women () had more limitations placed on them by parents as adolescents and began dating later. No gender difference in timing of the first serious relationship emerged. More young women had their first relationship with a Latino, and having a Latino boyfriend was associated with older partner age. In multivariate analyses, parental level of education was a stronger correlate of early dating experiences than generational status, and stronger findings emerged for young women than young men. The findings highlight the salience of gender as an organizer of early dating experiences among Latino adolescents.
Clinical and Procedural Predictors of Nurse Workload During and After Invasive Coronary Procedures: The Potential Benefit of a Systematic Radial Access
Authors: Amoroso Giovanni , Sarti Mascia , Bellucci Rita , Puma Francesca Li , D'Alessandro Silvia , Limbruno Ugo , Canova Alessia , Petronio Anna Sonia
Published: May 2005

Background: Invasive coronary procedures are increasing in number and complexity over time. This trend translates in an increased need for economical and human resources, among which is nurse staffing the most affected.

Aims: To identify possible predictors of nurse workload, during and after diagnostic and interventional procedures.

Methods: Two hundred and sixty consecutive patients were included: 52 and 208 patients underwent femoral and radial access, respectively. Nurse workload was calculated with a self-developed model.

Results: Cathlab nurse workload was 103 [63–156] min. Independent predictors of increased Cathlab nurse workload were: femoral access, failed radial access and cross-over, interventional procedures, procedural time, urgent procedures. Cathlab nurse workload was 174 [134–218] and 86 [58–126] min, for femoral and radial access, respectively ( p < 0.001).

Among the overall population, 174/260 patients (44 females, mean age 66 ± 11 years) were hospitalised at our Center after the procedure. Fifty-six and 118 patients had femoral and radial access, respectively.

Ward nurse workload was 457 [226–954] min. Independent predictors of increased Ward nurse workload were: access-site complication, length of in-hospital stay, admission to CCU, interventional procedures. Ward nurse workload was 386 [226–652] and 720 [314–1375] min, respectively for radial and femoral access ( p < 0.001).

Conclusions: A systematic radial access is an effective strategy for reducing nurse workload, both during, by simplifying nurse tasks in the CathLab, and after coronary invasive procedures, by preventing access-site complications, shortening in-hospital stays, and reducing admissions to CCU.
Contrast nephropathy post cardiac resynchronization therapy: An under‐recognized complication with important morbidity
Authors: Cowburn Peter J. , Patel Harshna , Pipes Rebecca R. , Parker John D.
Published: May 2005

Objectives

The aim of the study was to define the incidence of contrast nephropathy in patients undergoing cardiac resynchronization therapy (CRT).

Background

CRT is a promising new treatment for advanced heart failure. It is a technically demanding procedure with a recognized failure/complication rate. Contrast nephropathy is a well‐recognized complication of coronary angiography/intervention, but has not been described following CRT.

Methods

We performed a retrospective chart review of patients who had undergone CRT at Mount Sinai Hospital, a tertiary referral center for heart failure management, to define the incidence of contrast nephropathy in patients undergoing CRT. Contrast nephropathy was defined as the occurrence of a 25% or greater increase in serum creatinine within 48 h after contrast administration.

Results

Sixty‐eight patients underwent a total of seventy‐three procedures between October 1st 2000 and December 31st 2003. Ten patients (14%) developed contrast nephropathy. Three of these patients (4%) required hemofiltration and one died. Patients with creatinine ≥200 μmol/l (2.26mg/dl) were more likely to develop contrast nephropathy than those with creatinine <200 μmol/l (6/14 patients [43%] v 4/59 patients [7%], p<0.01). The mean length of hospital stay post‐procedure in patients developing contrast nephropathy was 19±18 (SD) days versus 4±5 days for those patients with stable renal function (p<0.01).

Conclusions

Contrast nephropathy is a frequent, but under‐recognized complication of CRT with important morbidity/mortality. The extended hospital stay associated with contrast nephropathy has important clinical and health care implications. Patients and physicians need to be aware of this potential risk.
The validity of a diagnosis of heart failure in a hospital discharge register
Authors: Ingelsson Erik , Ärnlöv Johan , Sundström Johan , Lind Lars
Published: May 2005

Background and aims

The accuracy of a diagnosis of heart failure (HF) in hospital discharge registers is largely unknown. We aimed to determine the validity of such a diagnosis in the Swedish hospital discharge register.

Methods and results

In a population‐based study of 2322 middle‐aged men (the ULSAM study), 321 participants were diagnosed with HF according to the Swedish hospital discharge register, during a median follow‐up time of 29 years. A review board examined the validity of the diagnosis according to the European Society of Cardiology definition of HF.

Eighty‐two percent of the possible cases were classified as having definite HF. An echocardiographic examination increased the validity to 88%. For patients treated at an internal medicine or cardiology clinic the validity was 86% and 91%, respectively. If HF was the primary diagnosis, the validity was 95%, irrespective of clinic type.

Conclusion

The HF diagnosis in the Swedish hospital discharge register appears slightly less precise than for acute myocardial infarction and stroke. For population‐based research, only those with a primary diagnosis of HF in the hospital discharge register should be regarded as definite HF cases, or alternatively the cases should be validated individually.
Tumour marker levels in patients with chronic heart failure
Authors: Varol Ercan , Ozaydin Mehmet , Dogan Abdullah , Kosar Feridun
Published: May 2005

Background

Carbohydrate Antigen 125 (CA 125), a marker for ovarian cancer has been reported to increase in relation to the severity of heart failure.

Objective

To evaluate the serum levels of CA 125 and other tumour markers, in patients with chronic heart failure.

Methods

Blood levels of CA 125 and other tumour markers were determined in 44 heart failure patients (16 males and 28 females; age 66.3±6.5 years) before and after optimal medical treatment. Levels were also evaluated in 30 healthy volunteers (11 males and 19 females; age 65.7±9.8 years). The results in the heart failure patients were grouped according to clinical status (New York Heart Association Class). The mean duration of follow‐up was 3±1.5 months.

Results

The mean serum level of CA 125 was 81.9±91 in the patient group and 7.5±4.8 in control group (p<0.001). The mean CA 19‐9 level in the patient group (16.8±16.6) was significantly higher than in the control group (4.5±2.6) (p<0.001). CA 125 levels increased as the New York Heart Association (NYHA) functional class increased (Class I/II: 17.7±22.4 U/ml; Class III: 99.6±92.1 U/ml; Class IV 136.4±102.8 U/ml; p<0.05). There were no significant differences in serum CA 125 and other tumour marker levels before and after optimisation of treatment. Significantly higher serum CA 125 levels were found in patients with pericardial effusion (p=0.002) when compared to patients without pericardial effusion.

Conclusion

Among the tumour markers evaluated, only CA 125 seems to be specifically related to the presence and severity of heart failure and also the presence of pericardial fluid. Therefore, measurements of CA 125 serum levels might be proposed for the serial assessment of heart failure. Whether CA 125 has a specific biological role in heart failure requires further investigation.
Hypotension is associated with diuretic resistance in severe chronic heart failure, independent of renal function
Authors: De Pasquale C.G. , Dunne J.S. , Minson R.B. , Arnolda L.F.
Published: May 2005

Background

Diuretic resistance and systemic hypotension are common in chronic heart failure (CHF), however, the two have not been associated.

Aims

Since blood pressure (BP) might be an important determinant of sodium excretion, we searched for an association between BP and diuretic dosage in severe CHF.

Methods

Our heart failure database was retrospectively reviewed for patients with severe left ventricular systolic dysfunction. The 54‐patient cohort was divided on the basis of frusemide dosage (high‐dose ≥250 mg daily, n=26).

Results

Patients taking high‐dose frusemide had higher serum creatinine, and lower systolic and diastolic BP. On logistic regression analysis, increased serum creatinine and reduced diastolic BP were independent predictors of the use of high‐dose frusemide. Grouping these variables into tertiles, the odds ratio for the use of high‐dose frusemide was 4.0 as diastolic BP decreased (p<0.01), and 6.8 as serum creatinine increased (p<0.001).

Conclusions

We have found an association between hypotension and the use of high‐dose frusemide in severe CHF, which is independent of renal function, and which may be an important physiologic mechanism of diuretic resistance in severe CHF.