bluuebunny/crossref_metadata_2025 huggingface dataset:
PSEUDO-DETERMINISTIC CHAOTIC SYSTEMS
Authors: VIANA R. L. , DE S. PINTO S. E. , BARBOSA J. R. R. , GREBOGI C.
Published: December 2003

We call a chaotic dynamical system pseudo-deterministic when it does not produce numerical, or pseudo-trajectories that stay close, or shadow chaotic true trajectories, even though the model equations are strictly deterministic. In this case, single chaotic trajectories may not be meaningful, and only statistical predictions, at best, could be drawn on the model, like in a stochastic system. The dynamical reason for this behavior is nonhyperbolicity characterized either by tangencies of stable and unstable manifolds or by the presence of periodic orbits embedded in a chaotic invariant set with a different number of unstable directions. We emphasize herewith the latter by studying a low-dimensional discrete-time model in which the phenomenon appears due to a saddle-repeller bifurcation. We also investigate the behavior of the finite-time Lyapunov exponents for the system, which quantifies this type of nonhyperbolicity as a system parameter evolves past a critical value. We argue that the effect of unstable dimension variability is more intense when the invariant chaotic set of the system loses transversal stability through a blowout bifurcation.
NONLINEAR DYNAMIC RESPONSE AND CHAOS OF A CRACKED ROTOR WITH TWO DISKS
Authors: QIN WEIYANG , MENG GUANG
Published: December 2003

In this paper, the nonlinear response and chaos of a cracked rotor with two disks are studied. Considering the breadth of crack in one rotor revolution, the motion equations of the system are derived and then solved. The results show that the rotor response is sensitive to the crack depth, rotating speed, damping ratio and imbalance. When a crack occurs, the frequency of swing vibration is a multiple of rotating speed (NΩ,N=2,3,…). There are three main routes for response to chaos, that is from quasi-periodic to chaos, from quasi-periodic to quasi-periodic bifurcation and then to chaos and the intermittence to chaos. The intermittence chaos occurs even for a small crack. With the intermittence chaos range there exists the periodic-doubling bifurcation with time. Larger imbalance parameter and damping ratio can suppress chaos. The diagram of time-phase is a useful way to analyze the nonlinear response.
STEADY-STATE ANALYSIS OF NONLINEARLY COUPLED CHUA'S CIRCUITS WITH PERIODIC INPUT
Authors: SAVACI F. A. , YALÇIN M. E. , GÜZELIŞ C.
Published: December 2003

In this paper, nonlinearly coupled identical Chua's circuits, when driven by sinusoidal signal have been analyzed in the time-domain by using the steady-state analysis techniques of piecewise-linear dynamic systems. With such techniques, it has become possible to obtain analytical expressions for the transfer functions in terms of the circuit parameters. The proposed system under consideration has also been studied by analog simulations of the overall system on a hardware realization using off-the-shelf components as well as by a time-domain analysis of the synchronization error.
BIFURCATION STRUCTURES OF PERIOD-ADDING PHENOMENA IN AN OCEAN INTERNAL WAVE MODEL
Authors: TANAKA GOUHEI , MURASHIGE SUNAO , AIHARA KAZUYUKI
Published: December 2003

In this paper, we study bifurcation structures of period-adding phenomena in an internal wave model that is a mathematical model for ocean internal waves. It has been suggested that chaotic solutions observed in the internal wave model may be related to the universal property of the energy spectra of ocean internal waves. In numerical bifurcation analyses of the internal wave model, we illustrate bifurcation routes to chaos and parameter regions where chaotic behavior is observed. Furthermore, it is found that the chaotic solutions are related to the period-adding sequence, that is, successive generations of periodic solutions with longer periods as a control parameter is changed. Considering the period-adding sequence as successive local bifurcations, we discuss a mechanism of the phenomena from the viewpoint of bifurcation analysis. We also consider similarity between period-adding phenomena in the internal wave model and ones in the Lorenz model.
RECONSTRUCTING DIFFERENTIAL EQUATION FROM A TIME SERIES
Authors: PETROV VALKO , KURTHS JUERGEN , GEORGIEV NIKOLA
Published: December 2003

This paper treats a problem of reconstructing ordinary differential equation from a single analytic time series with observational noise. We suppose that the noise is Gaussian (white). The investigation is presented in terms of classical theory of dynamical systems and modern time series analysis. We restrict our considerations on time series obtained as a numerical analytic solution of autonomous ordinary differential equation, solved with respect to the highest derivative and with polynomial right-hand side. In case of an approximate numerical solution with a rather small error, we propose a geometrical basis and a mathematical algorithm to reconstruct a low-order and low-power polynomial differential equation. To reduce the noise the given time series is smoothed at every point by moving polynomial averages using the least-squares method. Then a specific form of the least-squares method is applied to reconstruct the polynomial right-hand side of the unknown equation. We demonstrate for monotonous, periodic and chaotic solutions that this technique is very efficient.
CONTROLLING HYPERRADIANCE FROM CHAOTIC SOLITON OSCILLATOR IN JOSEPHSON JUNCTIONS
Authors: ZHANG XILI , HAI WENHUA , CHONG GUISHU
Published: December 2003

Using direct perturbation technology we study how to control the hyperradiance from chaotic soliton oscillator in two weakly coupled long Josephson junctions, by adjusting the bias current. The results reveal that the single soliton in a junction perturbed by a periodic solution of another junction possesses chaotic behavior. When the soliton is approximately synchronized with the periodic solution, the emitted power from the system rapidly increases. Although the boundedness conditions limit its maximal value, the chaotic soliton oscillator may emit much greater power than the soliton pair. Theoretical analysis and numerical simulation both demonstrate the results.
TWO MOMENT SYSTEMS FOR COMPUTING MULTIPHASE SEMICLASSICAL LIMITS OF THE SCHRÖDINGER EQUATION
Authors: GOSSE LAURENT , JIN SHI , LI XIANTAO
Published: December 2003

Two systems of hyperbolic equations, arising in the multiphase semiclassical limit of the linear Schrödinger equations, are investigated. One stems from a Wigner measure analysis and uses a closure by the Delta functions, whereas the other relies on the classical WKB expansion and uses the Heaviside functions for closure. The two resulting moment systems are weakly and non-strictly hyperbolic respectively. They provide two different Eulerian methods able to reproduce superimposed signals with a finite number of phases. Analytical properties of these moment systems are investigated and compared. Efficient numerical discretizations and test-cases with increasing difficulty are presented.
WAVE OPERATORS FOR THE NONLINEAR SCHRÖDINGER EQUATION WITH A NONLINEARITY OF LOW DEGREE IN ONE OR TWO SPACE DIMENSIONS
Authors: MORIYAMA KAZUNORI , TONEGAWA SATOSHI , TSUTSUMI YOSHIO
Published: December 2003

In this paper, we study the asymptotic behavior of solutions to the cubic and the quadratic nonlinear Schrödinger equations in one and two space dimensions, respectively. When the nonlinearity is of a form f = |u|p-1u, it is known that there exist scattered states if p > 1+2/n and there does not otherwise. Therefore we may consider the nonlinearities treated in the present paper to be of critical order for the existence of scattered states though their forms differ slightly from that given above. We prove, however, that there exist scattered states for these critical nonlinear Schrödinger equations, in other words, that the wave operators exist on a certain set of final states. Our proof is mainly based on the construction of suitable approximate functions that approach to solutions of nonlinear Schrödinger equations at t = ∞.
Serum Progastrin and Its Products, Gastric Acid Secretion and Serum Pepsinogen I in Gastric Cancer
Authors: Konturek Stanislaw J. , Konturek Peter C. , Bielanski W. , Karczewska Elzbieta , Zuchowicz Monika , Hartwich Artur , Rehfeld Jens F. , Goetze Jens P. , Hahn Eckhart G.
Published: December 2003

Background: Numerous studies have shown an association between Helicobacter pylori (Hp) infection and gastric cancer (GC). Study: This study was designed to determine the role of cytotoxin-associated gene A (CagA)-positive Hp infection, serum amidated gastrins and their precursor, progastrin, gastric acidity and serum pepsinogen I (PG-I) levels in gastric cancerogenesis in 74 cancer patients and in 77 age- and gender-matched controls. Serum IgG antibodies to Hp and CagA and levels of IL-8 and PG-I were measured by ELISA, while progastrin and amidated gastrin by specific radioimmunoassay. Results: The overall Hp and CagA seropositivity in GC patients were significantly higher (82 and 60%) than in matched controls (61 and 27%, respectively). Progastrin and amidated gastrin levels over their cutoff points (122 and 32 pM, respectively) were found in a significantly larger number of GC (59.4 and 44.5%) than in controls (9.0 and 16.8%, respectively). Histologically, all these GCs with increased serum progastrin and amidated gastrins were of intestinal type and showed CagA and Hp seropositivity. Serum IL-8 and gastric pH, above their cutoff points (pH >4.5), and serum PG-I level below its cutoff point (44.2 µg/l) were observed in a significantly higher number of GC patients as compared to controls. Conclusions: (1) GC patients have higher Hp and CagA seroprevalence than matched controls, confirming that CagA-positive Hp infection is associated with higher risk of GC; (2) serum levels of amidated gastrins and their precursor, progastrin, as well as IL-8 are significantly higher, while serum PG-I levels are reduced in intestinal type GC compared to controls, and (3) determination of high serum progastrin, amidated gastrins and IL-8 combined with low serum PG-I may be useful biomarkers of GC.
Arterial Structural Changes in Hypertension: A Consideration of Methodology, Terminology and Functional Consequence
Authors: Bund Stuart J. , Lee Robert M.K.W.
Published: December 2003

Alteration of resistance artery geometric design is a hallmark of established hypertension. In particular, there is an increased media thickness: lumen diameter ratio. In this review, consideration is given to the methods available for assessment of vascular structure, the terminology used to describe vascular structural changes in hypertension and the possible functional consequences of altered arterial design in the maintenance of the hypertensive state. In light of these considerations, a number of proposals are made concerning quantification strategies and descriptor terminologies. In particular, a simple descriptor terminology is proposed that describes such structural differences but makes no assumptions concerning the underlying processes that account for altered arterial structure in hypertension.
Metabolic activity and water vapour absorption in the mealwormTenebrio molitorL. (Coleoptera, Tenebrionidae): real-time measurements by two-channel microcalorimetry
Authors: Hansen Lars L. , Ramløv Hans , Westh Peter
Published: December 2003

This work describes a new calorimetric method in which the metabolic heat production and water exchange rates of an insect larva are measured simultaneously and in real time. The experimental set-up is based on two independent calorimetric cells, which are perfused by a stream of air at controlled relative humidity (RH). The resolution for metabolic heat flow and water flux is 1 μW and 5 μg h-1, respectively. The method was used to investigate water vapour absorption (WVA) in drought-stressed larvae of the common mealworm Tenebrio molitor. It was found that during exposure to a linear increment in RH of 3% per hour, the larvae initiated WVA upon passing a threshold value of 92.7±0.6%RH. The rate of water absorption subsequently increased to reach a maximal level of 86±6μg h-1, 10-15 h after passing the threshold value. Concomitantly, the RH in the calorimetric cell was reduced to 88.6±0.5%.

The metabolic heat production of the larvae was 5-6 J h-1g-1 wet mass in the initial part of the experiment. However, this value doubled 2-3 h prior to the onset of WVA, when the RH had reached 88%. This increase in metabolic heat production gradually tapered off over the following 24 h of WVA, during which time WVA remained high. Animals exposed to RH protocols that did not induce WVA showed no such anomalies in metabolic heat flow. This may suggest that the increased metabolism reflects the preparation of the WVA apparatus. Finally, the method was used to quantify water losses in the microgram range associated with wriggling and tracheal ventilation.
Development of respiratory function in the American locustSchistocerca americana
Authors: Greenlee Kendra J. , Harrison Jon F.
Published: December 2003

We hypothesized that oxygen delivery becomes more difficult for insects and tracheate arthropods as they progress throughout an intermolt period. During this time, body mass can more than double, yet the major tracheae and spiracles cannot be increased in size until molting. Also, tissue growth could compress air sacs used for convective gas exchange. To test these possibilities, we investigated the effect of within-instar growth on respiratory parameters, including CO2 emission rate, ventilation frequency, tidal volume and critical oxygen partial pressure(PO) for first-, third- and fifth-instar juveniles and adults of the American locust Schistocerca americana. We found that late-stage grasshoppers tended to have 40% higher total CO2emission rates but 15% lower mass-specific CO2 emission rates and 35% higher ventilation frequencies than early-stage animals. Maximal tracheal system conductance decreased by 20-33% at the end of an instar, possibly due to compression of air sacs. In addition, animals nearing the end of an instar had higher critical PO values for abdominal pumping, and late-stage adults had 50% lower tidal volumes, suggesting that increases in tissue mass throughout an instar may hinder the ability of animals to breathe deeply. Late-stage adults had lower critical PO values for CO2 emission, although this pattern was not found in any juvenile instars, indicating that late-stage juveniles compensate for decreased conductance by increasing ventilation frequency or the use of diffusive gas exchange. Our data suggest that late-stage arthropods are more vulnerable to hypoxia and may have reduced aerobic capacities and lower tissue PO s than early-stage arthropods.
Effects of leucokinin-VIII onAedesMalpighian tubule segments lacking stellate cells
Authors: Yu Ming-Jiun , Beyenbach Klaus W.
Published: December 2003

The diuretic peptide leucokinin is known to increase fluid secretion in Malpighian tubules of the yellow fever mosquito Aedes aegypti by increasing a transepithelial Cl- conductance. The present study sought to examine whether stellate cells provided this transepithelial conductance in Aedes Malpighian tubules as they do in Drosophila Malpighian tubules. Aedes Malpighian tubule segments with and without stellate cells were perfused in vitro for measurements of the transepithelial voltage (Vt),resistance (Rt) and Cl- diffusion potentials(DPCl). In 11 tubule segments containing both principal cells and stellate cells, 1 μmol l-1 leucokinin-VIII added to the peritubular bath immediately and significantly decreased Vt from 39.3±14.3 mV to 2.3±0.7 mV,decreased Rt from 12.4±2.6 kΩcm to 2.4±0.3 kΩcm, and increased DPCl from 8.2±1.2 mV to 42.1±5.4 mV. These effects of leucokinin-VIII were qualitatively and quantitatively similar in six tubule segments containing no stellate cells; Vt decreased from 37.8±7.0 mV to 3.4±0.6 mV, Rt decreased from 8.8±2.1 kΩcm to 1.7±0.2 kΩcm, and DPClincreased from 5.8±2.6 mV to 50.0±2.1 mV. Thus, stellate cells are not required for signaling or mediating the effects of leucokinin in Malpighian tubules of Aedes aegypti. The results further support previous observations that principal cells signal the effects of leucokinin to increase the Cl- conductance of the paracellular pathway through septate (or tight) junctions.
Future migratory behaviour predicted from premigratory levels of gill Na+/K+-ATPase activity in individual wild brown trout(Salmo trutta)
Authors: Nielsen Christian , Aarestrup Kim , Nørum Ulrik , Madsen Steffen S.
Published: December 2003

The relationship between premigratory gill Na+/K+-ATPase activity, determined at two dates during spring, and future migratory behaviour was investigated using non-lethal gill biopsies and PIT-tagging in wild brown trout (Salmo trutta) from two tributaries. No significant relationship between future migratory strategy(individuals eventually becoming migrants or residents) and gill Na+/K+-ATPase activity was found in late February–early March. By contrast, in mid-April, a highly significant logistic regression equation identifying the migratory strategy in 93% of the 75 individuals was obtained. The ability of this regression model from the tributaries to predict future migratory behaviour in an independent group of trout caught in early April in the mainstream was evaluated. A threshold probability of migration was used to predict the behaviour of the mainstream individuals as either future migrants or residents. The maximum percentage of correct predictions of future migratory behaviour in mainstream fish was observed at threshold probabilities between approximately 0.15 and 0.45(corresponding to threshold gill Na+/K+-ATPase activities between 2.7 and 3.7 μmol ADP mg–1 protein h–1), with an average of 91% of the predictions being correct. The present study shows that a non-lethal premigratory biochemical measurement can successfully select individual brown trout with high probability of migration.
Surface Acidity of Cesium Hydrogen Salts of 12-Tungstophosphoric Acid Characterized by Low-Temperature CO Adsorption
Authors: Saito Takaya , Koyano Gaku , Misono Makoto
Published: December 2003

The surface acidity of cesium hydrogen salts of 12-tungstophosphoric acid, CsxH3−xPW12O40 (Csx; x = 2 - 3), has been characterized by FT-IR measurements of the low-temperature adsorption of CO. In the region of the CO stretching, CO adsorbed on H+ (2165 cm−1) and CO on Cs+ (2154 cm−1) were distinguished. The relative intensity of 2165 cm−1 band to 2154 cm−1 band increased linearly with the formal H+/Cs+ ratio, (3−x)/x. The integrated intensity of 2165 cm−1 changed in parallel with the catalytic activity for the surface-type reactions.
Absolute Stereochemistry and CD Spectra of Resolved Enantiomers of the Colored Form of a Photochromic Dithienylethene
Authors: Yokoyama Yasushi , Hosoda Naoya , Osano Yasuko T , Sasaki Chizuko
Published: December 2003

The colored form of photochromic 1,2-bis(5-hydroxymethyl-2-methyl-3-thienyl)hexafluorocyclopentene was resolved into enantiomers by HPLC. The absolute stereochemistry of an enantiomer was determined on its bis(4-chlorobenzoate). The CD spectra and optical rotation of the resolved colored form were measured.
Isolation and Molecular Structure of Persilyalated [5]Radialene: Intramolecular Cyclization of a Macrocyclic Pentayne with Mn(CO)3(Me-Cp)
Authors: Matsuo Tsukasa , Fure Hidetoshi , Sekiguchi Akira
Published: December 2003

Persilyl-substituted [5]radialene (2) was isolated as orange crystals by the intramolecular cyclization of 3,3,6,6,8,8,11,11,14,14,16,16,19,19,21,21-hexade camethyl-3,6,8,11,14,16,19,21-octasilacyclohenicosa-1,4,9,12,17-pentayne (1) with an excess molar amount of [Mn(CO)3(Me-Cp)] by irradiation (λ > 300 nm) under reflux in THF. The molecular structure and properties of the persilyated [5]radialene 2 are described.
Solvothermal Preparation of Silver Chalcogenides Ag2E (E = S, Se, Te)
Authors: Yu Shu-Hong , Han Zhao-Hui , Yang Jian , Yang Ru-Yi , Xie Yi , Qian Yi-Tai
Published: December 2003

Well crystallized silver chalcogenides were synthesized by a solvothermal reaction of silver oxalate Ag2C2O4 with chalcogens in organic solvents at relatively low temperature (140 °C-180 °C). It was found that both solvents and temperature have significant influence on the synthesis of silver chalcogenides.
Effect of Support Texture on Enantioselective Hydrogenation of (E)-α-Phenylcinnamic Acid with Cinchonidine-Modified Palladium Catalysts
Authors: Nitta Yuriko , Okamoto Yasuaki
Published: December 2003

The texture of support materials has decisive influence on the behavior of cinchonidine-modified palladium catalysts in the enantioselective hydrogenation of (E)-α-phenylcinnamic acid, which suggests an important role of pore diffusion in the determination of the selectivity. Palladium metal particles located in micropores of the support have detrimental effect; nonporous ultra fine materials are preferable.
Remarkable Addition Effect of In and Ga in the NO-CO Reaction over Pd/SiO2
Authors: Naito Shuichi , Hasebe Tohoru , Miyao Toshihiro
Published: December 2003

Addition of In or Ga to Pd/SiO2 accelerated the rate of NO-CO reaction dramatically, and N2O and CO2 were formed steadily even at room temperature. XRD measurements revealed that a Pd-In intermetallic compound plays an important role. The ensemble effect of In atoms weakened the adsorption of CO and NO, which may open a new reaction route for N2O formation.
Preparation of a New π-Conjugated Polymer Chelating Ligand, Poly(2,2′-bipyridimidine-5,5′-diyl), and Its Metal Complexes
Authors: Yamamoto Takakazu , Hayashida Naoki , Maruyama Tsukasa , Kubota Kenji
Published: December 2003

A New π-conjugated chelating polymer ligand, poly(2,2′-bipyrimidine-5,5′-diyl), with a molecular weight higher than 1800 has been prepared. The polymeric ligand forms complexes with Ru(bpy)22+ and Os(bpy)22+.
Crystal Structures and Conducting Properties of PF6 and AsF6 Salts of a Novel Benzo[c]furan-Extended Donor: The Role of Inter-Column Interactions
Authors: Takahashi Kazuko , Ise Toshihiro , Mori Takehiko , Mori Hatsumi , Tanaka Shoji
Published: December 2003

The PF6 and AsF6 salts of a new benzo[c]furan-extended donor have been prepared. It has been clarified that the inter-column interactions connecting the tetrameric donor columns play an important role in the conduction of these salts.
Photochemistry and Absolute Stereochemistry of Unique Chiral Olefins, trans- and cis-1,1′,2,2′,3,3′,4,4′-Octahydro-3,3′-dimethyl-4,4′-biphenanthrylidenes
Authors: Koumura Nagatoshi , Harada Nobuyuki
Published: December 2003

Photochemistry of unique chiral olefins, (3R,3′R)-(P,P)-(E)-(−)-1,1′,2,2′,3,3′,4,4′-octahydro-3,3′-dimethyl-4,4′-biphenanthrylidene 3 and its isomers (3R,3′R)-(P,P)-(Z)-(+)-4 and (3R,3′R)-(M,M)-(E)-(+)-5, was studied and the absolute stereostructure of (+)-5 was determined by X-ray crystallographic and chemical correlation studies.
Be Careful When You Want to Use Buffers in Aqueous Solutions of Cyclodextrins. Effect of Buffers on the Formation Constants of 3-Hydroxy-2-Naphthoic Acid with β-Cyclodextrin
Authors: Yi Zhengping , Huang Zhengzi , Yu Junsheng , Chen Huilan
Published: December 2003

Formation constants of 3-hydroxy-2-naphthoic acid with β-cyclodextrin were determined in aqueous solutions without and with almost all the buffers usually used by steady-state fluorescence Benesi-Hildebrand method. The results show that buffers have influence on the formation constants and we suggest that buffers should no be used in aqueous solutions of cyclodextrins unless the experimental error is unacceptable.
Formation and Structure of Mixed Quaternary Chelates with Late-Lanthanide Metal Ions
Authors: Hayashi Katsura , Nagao Noriharu , Harada Kazumasa , Haga Masa-aki , Fukuda Yutaka
Published: December 2003

We have newly obtained two series of late-lanthanide metal complexes with three different kinds of chelating ligands (quaternary system), [Ln(dike)3−n(NO3)n(terpy)] where Ln(III) = Er(III) or Yb(III), dike = β-diketonate such as acetylacetonate (acac) or 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac), and terpy = 2,2′:6′,2″-terpyridine; n = 2 (for acac) or 1 (for hfac). Crystal structures for the Yb(III) complexes show that in both series the pentagonal plane around the central Yb3+ ion with terpy and one dike ligand is formed. The other chelating ligands coordinate up and down from the plane to form totally 9 coordination around Yb3+.
The Syntheses of (Chloro) Iron(II) Complexes by Using Tridentate Polypyridine Ligands
Authors: Ito Masami , Takita Yu-saku , Sakai Ken , Tubomura Taro
Published: December 2003

Two (chloro)iron(II) complexes have been synthesized and characterized by crystallography.
New Clay-Supported Chiral Rhodium Complexes: Interlayer Modification with Structural Tuning Guests and Asymmetric Hydrogenation
Authors: Sento Tadashi , Shimazu Shogo , Ichikuni Nobuyuki , Uematsu Takayoshi
Published: December 2003

The novel host-guest catalysts, in which a chiral rhodium complex was intercalated into structural tuning guests modified smectites, were synthesized, and drastic change in catalysis was observed depending on the orientation of guest molecules.
Catalytic Activity for Methanol Synthesis over a Copper-Lanthanide Oxide Complex System Prepared from a Copper-Lanthanide Complex Oxide of Cu6O8Yb(NO3)
Authors: Sakata Yoshihisa , Nobukuni Satoshi , Hashimoto Taiji , Takahashi Fumiyoshi , Imamura Hayao , Tsuchiya Susumu
Published: December 2003

High catalytic performance for methanol production from CO and H2 was confirmed over copper-lanthanide oxide binary catalyst which was prepared from a characteristic copper-lanthanide complex oxide of Cu6O8Ln(NO3). The catalyst exhibited high activity from lower temperatures compared with copper-zinc catalyst systems under the same condition.
Anion Exchange between Sulfate Ion and Hydrogenphosphate Ion to Form Mesoporous Zirconium-Phosphorus Complex Oixde
Authors: Wu Peng , Iwamoto Masakazu
Published: December 2003

Formation of zirconium-phosphorus complex oxide with stable hexagonal pore structure has been clarified to result from anion exchange of HPO42− ions for SO42− ions in surfactant-assisted zirconium oxide during phosphoric acid treatment.
Electromotive Force Measurement for an Iron-Oxygen Cell in High Magnetic Field
Authors: Shinohara Kenji , Aogaki Ryoichi
Published: December 2003

Using iron-oxygen reaction in sodium chloride solution, a new type of electrochemical cell operated by high magnetic field was fabricated. The electromotive force (EMF) of this cell reached about 8 mV. This value was about 100 times larger than expected by the magnetic energy.
Interfacial Recognition between Reconstituted Myoglobin Having Charged Binding Domain and Electron Acceptor via Electrostatic Interaction
Authors: Hayashi Takashi , Tomokuni Atsushi , Mizutani Tadashi , Hisaeda Yoshio , Ogoshi Hisanobu
Published: December 2003

Myoglobins reconstituted with synthetic zinc porphyrins having multiple carboxylic acid or alkylamine groups bound to the terminal of peripheral side chains can bind cationic methyl viologen or anionic hexacyanoferrate, respectively, via electrostatic interaction, where the distribution of the charged amino acid residues on the myoglobin surface has an influence on complex formation between the protein and its partner.
Ladder-Type Phthalocyanine Conductor, [PXX][Co(Pc)(CN)2] (PXX = peri-xanthenoxanthene, Co(Pc)(CN)2 = dicyano(phthalocyaninato)cobalt(III))
Authors: Takano Susumu , Naito Toshio , Inabe Tamotsu
Published: December 2003

Electrochemical oxidation of PXX and [Co(Pc)(CN)2]− in acetonitrile gives a highly conducting crystal containing two-leg ladder chains of the partially oxidized Co(Pc)(CN)2 units. The doubling of the one-dimensional chains makes the electrical properties quite different from those in the single chain conductor.
High Enantioselectivity in the Electron Transfer Reaction between a Ru(II) Complex of Menbpy Anion Radical, [Ru(menbpy)3]+ [menbpy = 4,4′-di{(1R,2S,5R)-(−)-menthoxycarbonyl}-2,2′-bipyridine] and [Co(acac)3]: A Pulse Radiolysis Study
Authors: Hamada Taisuke , Sakaki Shigeyoshi , Brunschwig Bruce S , Fujita Etsuko , Wishart James F
Published: December 2003

One-electron reduction of [Ru(menbpy)3]2+ [menbpy = 4,4′-di{(1R,2S,5R)-(−)-menthoxycarbonyl}-2,2′-bipyridine] by pulse radiolysis produces a Ru(II) complex of a menbpy-centered anion radical, which reduces Δ-[Co(acac)3] more rapidly than Λ-[Co(acac)3] with an enantioselectivity of 2.7 in 85% EtOH/H2O.
Synthesis of Dihydropyrroles by the Intramolecular Addition of Alkylideneaminyl Radicals Generated from O-2,4-Dinitrophenyloximes of γ,δ-Unsaturated Ketones
Authors: Uchiyama Katsuya , Hayashi Yujiro , Narasaka Koichi
Published: December 2003

Alkylideneaminyl radicals are generated from O-2,4-dinitrophenyloximes of γ,δ-unsaturated ketones by treatment with NaH and 3,4-methylenedioxyphenol. The resulting radical species successively add to the olefinic moiety intramolecularly to afford 3,4-dihydro-2H-pyrroles.
Oxidation of Cyclohexane with Molecular Oxygen Efficiently Catalyzed by Di-Iron(III)-Substituted Silicotungstate, γ-SiW10{Fe(OH2)}2O386−, Including Radical-chain Mechanism
Authors: Nozaki Chika , Misono Makoto , Mizuno Noritaka
Published: December 2003

The tetrabutylammonium salt of γ-SiW10{Fe(OH2)}2O386− showed high turnover number of 135-147 for the oxidation of cyclohexane with 1 atm molecular oxygen and the value is of the highest level among silicotungstates with various iron contents and other catalysts reported. Results obtained with radical initiator and scavenger, and the selectivity for oxygenation of adamantane suggest that the reaction involves a radical-chain path.
Efficient and Selective Epoxidation of Alkenes with Sodium Periodate Using Supported Manganese Porphyrins under Ultrasonic Irradiation
Authors: Tangestaninejad Shahram , Mirkhani Valiollah
Published: December 2003

Epoxides are readily obtained in high yields and good selectivities by ultrasonic irradiation of alkenes and sodium periodate in the presence of catalytic amounts of manganese porphyrins supported on polyvinylpyridine and IRA-900 ion-exchange resin.
Selective Oxidation of Propylene to Propylene Oxide or Propionaldehyde over Au Supported on Titanosilicates in the Presence of H2 and O2
Authors: Uphade B S , Tsubota Susumu , Hayashi Toshio , Haruta Masatake
Published: December 2003

Gas phase selective oxidation of propylene to propylene oxide (PO) or propionaldehyde (PA) in the presence of H2 and O2has been carried out with a propylene conversion in the range of 0.5-3.7% over gold deposited on titanosilicates by deposition-precipitation (DP) method; PO was obtained with a selectivity above 90% at the temperature range of 50 °C-120 °C whereas PA was obtained at temperatures higher than 200 °C with a selectivity above 70% over throughly washed catalysts with low Au loadings.
Zirconium Sulfate–Surfactant Micelle Mesostructure as an Effective Remover of Selenite Ion
Authors: Takada Hitoshi , Watanabe Yoshimasa , Iwamoto Masakazu
Published: December 2003

Selenite ion in an aqueous solution could be effectively trapped in the zirconium sulfate–surfactant micelle mesostructure (ZS). The reaction proceeded through anion exchange between HSO4− in ZS and HSeO3−. The maximum sorption capacity of ZS for HSeO3− was 2.47 mmol g−1 at 303 K.
Crystal Structure of Pyrazolato-bridged Copper(I) Polynuclear Complexes
Authors: Fujisawa Kiyoshi , Ishikawa Yoko , Miyashita Yoshitaro , Okamoto Ken-ichi
Published: December 2003

We prepared a series of copper(I) polynuclear complexes bridged by three different alkyl substituted pyrazolate anions. From X-ray analysis, these differences reflected their molecular structures. These structural changes also reflected some properties in their IR, far-IR, UV–vis, and NMR spectra.
Quenching of Peroxynitrite by Lycopene in Vitro
Authors: Yokota Tadashi , Ohtake Teturou , Ishikawa Hajime , Inakuma Takahiro , Ishiguro Yukio , Terao Junji , Nagao Akihiko , Etoh Hideo
Published: December 2003

We investigated in vitro the reactivity of lycopene toward peroxynitrite and identified the reaction products after scavenging peroxynitrite. On the basis of these studies, we propose a mechanism for peroxynitrite scavenging action of lycopene.
The Reduction of Broken Appointments in General Dental Practice
Authors: Patel Piyush , Forbes Michael , Gibson John
Published: December 2003

Purpose of study

Accumulation of time lost because of broken appointments in general dental practice can lead to an inefficiently-run practice and may also lead to reduced financial income. This study assessed the reasons for patients failing to attend and analysed the effect of two simple interventions in reducing the numbers of broken appointments.

Basic procedures

This study audited the causes of broken appointments in a Glasgow dental practice over a four-month period and, in a second four-month period, analysed the effect of using two new methods of patient information in reducing the number of broken appointments in two target groups of the practice population.

Main findings

The majority of patients failing to attend for dental treatment were unemployed. Simple changes to recall letters and appointment cards significantly reduced the rates of failed appointments in patients attending the practice.

Principal conclusions

Simple modification to existing practice systems (recall letters and appointment cards) led to a statistically significant reduction in the number of broken appointments.
Advances in Periodontology
Authors: Tonetti Maurizio S
Published: December 2003

Advances in periodontal science and practice over the last decade have radically changed the understanding of periodontal diseases and have opened new, exciting prospects for both medical and surgical therapy of periodontal diseases. Establishment of the aetiology and pathogenesis of periodontitis, understanding of the unique genetic and environmental susceptibility profile of affected subjects, and recognition of the systemic implications of periodontal infections are the key research findings. The use of randomised, controlled, clinical trials has allowed the development of evidence-based periodontology. Adjunctive antimicrobial therapy, regenerative periodontal surgery, periodontal plastic surgery, bone regeneration surgery in the light of implant treatment, and advanced soft tissue management at implant sites have radically changed practice.
An Analysis of the Qualitative Factors which Influence
Authors: Gray Margaret M , Bradnock Gillian , Gray Helen L
Published: December 2003

Introduction and method

The qualitative data volunteered as responses to open questions in a self-administered questionnaire study we re analysed to identify the psychological factors influencing young people's behaviour in relation to orthodontic care and to gain an understanding of the psychological factors which influence adolescents’ acceptance of orthodontic care. The study was conducted in all Walsall and Dudley secondary schools.

Results and discussion

The responses of the young people who were in year 10 of education with an average age of 15.0 years demonstrated the importance of personal constructs, peer group and media influences, parental influences, conflicting messages, teasing, symptom perception, appearance and self-image, and interpersonal relationships in determining whether or not young people either seek and accept or reject orthodontic treatment.

Conclusion

The study concluded that it is essential that clinicians involve patients fully and honestly in discussions concerning their orthodontic therapy in order to enable them to make a considered consent.
An Overview of Reasons for the Placement and Replacement of Restorations
Authors: Deligeorgi Vassiliki , Mjör Ivar A , Wilson Nairn HF
Published: December 2003

Aim

Surveys on reasons for the placement and replacement of restorations have been conducted in various countries. The purpose of this paper is to bring together and review the data of 10 such surveys with similar methodology.

Method

The studies reviewed are all based on the protocol described by Mjör in 1981.

Results

The surveys reviewed provide data on the reasons for the placement and replacement of a total of 32,777 restorations. Notwithstanding differences between countries, different groups of practitioners and minor variations in methodology, the data included in the selected surveys indicate that everyday clinical practice in Scandinavia, UK and USA during the 1980s and 1990s has involved more replacement than initial restorations, with the ratio of initial to replacement restorations ranging from 1:1.1 to 1:2.4 for amalgam and 1:1.1 to 1:3.8 for composite materials. Primary caries has been consistently found to be the principal reason for the provision of initial restorations of amalgam and composite. The principal reason for the replacement of restorations of amalgam and composite has remained secondary caries as diagnosed clinically. Material failures (marginal degradation, discoloration, bulk fracture and loss of anatomic form) accounted for the replacement of more restorations of composite than amalgam. Recent surveys have reported secondary caries as the principal cause of failure of restorations of glass-ionomer cements and related materials.

Conclusions

The clinical diagnoses of caries may continue to be found to account for the placement and replacement of most intracoronal restorations. Surveys of the type reviewed provide valuable insight into patterns of provision of dental care and highlight research priorities in relation to direct restorations.
Product Complements and Substitutes in the Real World: The Relevance of “Other Products”
Authors: Shocker Allan D. , Bayus Barry L. , Kim Namwoon
Published: December 2003

In the real world, buyer demand for a product can depend directly and indirectly on the marketing efforts of “other products” in different categories. The authors offer a behavioral rationale for the existence of the effects of “other products'” marketing efforts and propose a taxonomy of possible intercategory relationships. The discussion enables the authors to identify several promising new research directions.
Beyond Adoption: Development and Application of a Use-Diffusion Model
Authors: Shih Chuan-Fong , Venkatesh Alladi
Published: December 2003

The study tests a use-diffusion model in the context of home technology use. The authors combine two constructs, variety and rate of use, to yield four user segments. The results show that user segments vary on the basis of social context and technological makeup of the household as well as personal factors and external influences. Furthermore, user segments differ with regard to users’ satisfaction with technology and interest in acquiring future technologies.
Antecedents of Export Venture Performance: A Theoretical Model and Empirical Assessment
Authors: Morgan Neil A. , Kaleka Anna , Katsikeas Constantine S.
Published: December 2003

Both the size and the rapid growth of global exporting have focused the attention of marketing researchers on the factors associated with firms’ export performance. However, knowledge of this increasingly important domain of marketing activity remains limited. To address this knowledge gap, the authors draw on the strategy and marketing literature to develop an integrative theory of the antecedents of export venture performance. The interplay among available resources and capabilities, competitive strategy decisions, and competitive intensity determines export venture positional advantages and performance outcomes in the theoretical model. The authors empirically assess predicted relationships using survey data from 287 export ventures. Results broadly support the theoretical model, indicating that resources and capabilities affect export venture competitive strategy choices and the positional advantages achieved in the export market, which in turn affect export venture performance outcomes. In contrast to structure–conduct–performance theory predictions, the data indicate that the competitive intensity of the export marketplace does not have a direct effect on export venture positional advantages or performance. However, competitive intensity moderates the relationship between export venture competitive strategy choices and the positional advantages realized.
Two Models of Adolescent Self‐Mutilation
Authors: Ross Shana , Lee Heath Nancy
Published: December 2003

Currently little research exists examining the theoretical underpinnings of self‐mutilation (SM) in community samples of adolescents. Two models, the hostility and anxiety reduction models, were simultaneously tested in order to determine whether SM in adolescence was characterized by greater feelings of anxiety and hostility. Four hundred and forty students were screened for the presence of SM. Sixty‐one students who indicated that they hurt themselves as well as a comparison group of non‐SM students completed the Hostility and Direction of Hostility Questionnaire (HDHQ), the Beck Anxiety Inventory (BAI), and an interview. Results indicate support for the hostility model of SM. Students who SM reported significantly more anxiety and more intropunitive and extrapunitive hostility. In addition, prior to self‐mutilating feelings of both hostility and anxiety were described. Results are discussed with reference to both theoretical models.
A Meta‐Analysis of Police Suicide Rates: Findings and Issues
Authors: Loo Robert
Published: December 2003

Meta‐analyses of police suicide rates and ratios to the comparison population were conducted using 101 samples from the literature. The large effect sizes (ES = .74) showed that suicide rates based on short time frames were significantly higher than for long time frames. There were regional differences such that rates in the Americas and Europe were higher than in the Caribbean and Asian regions. There were differences in rates between federal, regional, and municipal police forces. Issues researchers need to address include the use of long time frames; the reporting of more complete suicide statistics, including breakdowns by year, sex, and ethnic groups; and the rates for population comparison groups.
Evaluation of ovotransferrin-matrix metal-affinity metalloprotein chromatography for Pu(IV) separations
Authors: Myers W. K. , Ruggiero C. E. , Reilly S. D. , Neu M. P.
Published: December 2003

Metal-Affinity metalloprotein chromatography has been suggested to have potential for selectively removing actinides from solution. To evaluate this potential, characterization of Pu(IV) and Fe(III) binding to an ovotransferrin-Sepharose™ 4B matrix, with oxalate and carbonate synergistic anions, was performed. Metal binding capacity was determined for metal concentrations ranging from 2×10-6 to 1×10-3M Fe(III) and 2.9×10-5 to 2.6×10-4M Pu(IV), where both metals were added as a solution of 10:1 nitrilotriacetic acid:metal. Metal binding capacity was also determined over the pH range 3.0 to 9.2. The metal binding properties of the immobilized ovotransferrin were found to differ from those reported for free-protein studies. Distribution coefficients were low: for metal solution concentrations of 0.02, 0.04, 0.10, and 0.20mM, coefficients were 540, 180, 23, and 12mL/g for Fe(III) and 20, 12, 7.2, and 6.0mL/g for Pu(IV), respectively. The capacity of the material was less dependent on pH than expected, varying by only two μmoles metal/g matrix for both Fe(III) and Pu(IV) over the pH range of 4.2 to 9.5. This study illustrates limitations of metalloprotein chromatography for Pu(IV) separation.
Role of ligand basicity and stereochemistry in the extraction of plutonium(IV) isoxazolonates
Authors: Mohapatra P. K. , Manchanda V. K.
Published: December 2003

The extraction behaviour of plutonium (IV) was investigated from nitric acid and perchloric acid using 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) as well as a mixture of HPBI and tri-n-octyl phosphine oxide (TOPO) in xylene. Studies on the binary extraction system Pu(IV)-HPBI indicated extraction of species of the type Pu(PBI)4. In the presence of TOPO, while species of the type Pu(PBI)3(ClO4)·(TOPO) and Pu(PBI)4·TOPO were co-extracted from perchloric acid medium, a mixture of Pu(PBI)2(NO3)2·2TOPO, Pu(PBI)3(NO3)·(TOPO) and Pu(PBI)4·TOPO were co-extracted from nitric acid medium. In addition to the electronic factors, steric factors were found to play a significant role during the formation of binary/ternary/quaternary complexes. The steric hindrance due to the unusual conformation of the isoxazolone led to lowering of the equilibrium constants for both the binary and ternary extraction systems. Possible steric factor influences are explained with the help of molecular modelling.
Sorption kinetics and impact of temperature, ionic strength and colloid concentration on the adsorption of plutonium-239 by inorganic colloids
Authors: Lu Ningping , Reimus Paul W. , Parker Gary R. , Conca James L. , Triay Inès R.
Published: December 2003

Plutonium (Pu) is one of the primary actinides of concern for long-term disposal and storage of nuclear waste. Strong sorption of Pu onto colloids of iron oxide, clay, and silica could result in colloid-facilitated transport of this actinide in groundwater systems. However, fundamental data on Pu sorption to colloids is sparse, resulting in large uncertainties in long-term predictions of colloid-facilitated Pu transport. This sparseness of data and the potential to significantly reduce uncertainties in predictive models served as a motivation for this study. The authors investigated the sorption and desorption behaviors of239Pu(V) on three types of inorganic colloids (hematite, montmorillonite and silica), with adsorption being measured as a function of temperature, ionic strength and colloid concentration for each colloid. Natural ground water collected from Well-13 near Yucca Mountain, Nevada, and synthetic ground water (SYN.J-13) were used in the experiments. The results indicated that the adsorption of239Pu(V) onto hematite colloids was faster and had a higher partition coefficient (Kp, ml g-1) than onto montmorillonite or silica colloids in both J-13 and SYN.J-13 waters. Temperature did not significantly influence the adsorption of239Pu(V) onto hematite and silica colloids, but the adsorption of239Pu(V) onto montmorillonite colloids increased significantly with increasing temperature. While ionic strength did not significantly influence the adsorption of239Pu(V) onto hematite colloids, an increase in ionic strength decreased the adsorption of239Pu onto montmorillonite and silica colloids. Adsorption of239Pu(V) per unit mass of colloid was much higher at low colloid concentrations than at high colloid concentrations. Desorption of239Pu from239Pu-loaded colloids was considerably slower than the adsorption process.
Sorption of Np(V) by synthetic hydroxyapatite
Authors: Moore Robert C. , Holt Kathleen , Zhao Hongting , Hasan Ahmed , Awwad Nasser , Gasser Mona , Sanchez Charles
Published: December 2003

The sorption of Np(V) to synthetic hydroxyapatite was determined in batch experiments in a 0.1M NaClO4solution. The hydroxyapatite used was of high purity as determined by SEM, EDS, XRD, FT-IR and ICP-MS analysis. Results from kinetic experiments with an initial Np(V) concentration of 1×10-7to 1×10-6M indicate the sorption process is relatively fast with more than 90 of the Np(V) being sorbed in approximately 3 hours. Equilibrium experiments performed over the pH range of 6 to 11 indicated sorption is strongly pH dependent with distribution coefficients,Kdvalues (mL/g), increasing from 123L/mole at pH 6 to 69200L/mole at pH 8.5.Kdvalues are observed to decrease as pH further increases. Data points over a range of Np(V) concentrations were collected at pH 8 and fitted to the Langmuir isotherm model for simple adsorption. The Langmuir equation gave an excellent representation of the data. Langmuir parameters were determined to beCa=0.032mole/mole andK=1.22×106L/mole, indicating the high affinity of hydroxyapatite for Np(V) adsorption.