bluuebunny/crossref_metadata_2025 huggingface dataset:
The olfactory pathway for individual recognition in the American lobsterHomarus americanus
Authors: Johnson Meg E. , Atema Jelle
Published: July 2005

Individual recognition in the lobster Homarus americanus(Milne-Edwards), is based on detection of urine pheromones viachemoreceptors of the lateral antennular flagellum. The specific sensory pathway mediating this recognition is not known. Most of the chemoreceptor cells of this flagellum are found in the unimodal aesthetasc sensilla and project specifically to the glomeruli of the olfactory lobe in the brain. Additional chemoreceptor cells are located among mechanoreceptor cells in bimodal sensilla, including the guard hairs; they do not project to the olfactory lobe. This neuroanatomy suggested that aesthetascs were essential to all complex chemosensory tasks until it was shown that spiny lobsters Panulirus argus can still perform complex food odor discrimination and localization tasks without aesthetascs. Here, we demonstrate that the aesthetascs of H. americanus contain the chemoreceptors necessary for individual recognition of familiar opponents. In contrast to intact and guard hair-shaved animals, lobsters with aesthetascs removed did not recognize previous opponents as shown by second encounters statistically similar in length and aggression to first-encounter fights. Non-aesthetasc chemosensory pathways were incapable of rescuing opponent recognition. Subsequent lesion of all remaining chemoreceptor cells (by immersion in distilled water) abolished recognition and renewed fighting.
Effects of series elasticity and activation conditions on muscle power output and efficiency
Authors: Lichtwark G. A. , Wilson A. M.
Published: July 2005

The activation of a muscle depends on the function that it is performing and on the architectural properties of that muscle; the two are inextricably linked. Activation conditions such as activation timing, duration and amplitude can be varied throughout a cyclical movement (such as locomotion)and the length change of the whole muscle tendon unit (MTU) can also be varied. Architecturally, muscles have a range of fibre lengths, maximum force-producing capabilities and stiffness of the series elastic element(SEE). In the present work we use a model to explore the relationship between power output and efficiency of a muscle across a range of contraction conditions. We have also examined the mechanical and energetic effects of changing muscle architecture within the model. Our results indicate that whilst there are clear optimal conditions for achieving maximum power output and maximum efficiency, the design of the muscle allows high levels of both to be achieved over a range of activation conditions. This range changes with both SEE compliance and the amplitude of the cyclical length change. The results suggest that a compliant SEE allows a muscle to function closer to the maximum of both power output and efficiency. In addition, by varying the amplitude of the activation level, the efficiency can theoretically remain unchanged, whilst the power output can be modulated.
Temporal organization of bi-directional traffic in the antLasius niger(L.)
Authors: Dussutour Audrey , Deneubourg Jean-Louis , Fourcassié Vincent
Published: July 2005

Foraging in ants is generally organized along well-defined trails supporting a bi-directional flow of outbound and nestbound individuals and one can hypothesize that this flow is maximized to ensure a high rate of food return to the nest. In this paper we examine the effect of bottlenecks on the temporal organization of ant flow. In our experiments ants had to cross a bridge to go from their nest to a food source. Two types of bridges were used:one with and one without bottlenecks. Traffic counts show that, in spite of the bottlenecks and the reduction of path width, the volume of traffic and the rate of food return were the same on both bridges. This was due to a change in the temporal organization of the flow: when path width decreases alternating clusters of inbound and outbound ants were observed crossing the bridge. This organization limits the number of head-on encounters and thus allows to maintain the same travel duration as on the wide bridge. A model is proposed to assess in various conditions the importance of the behavioural rules observed at the individual level for the regulation of traffic flow. It highlights how the interplay between the value of the flow and cooperative behaviours governs the formation and size of the clusters observed on the bridge.
Nitric oxide in control of luminescence from hatchetfish(Argyropelecus hemigymnus) photophores
Authors: Krönström Jenny , Holmgren Susanne , Baguet Fernand , Salpietro Lorenza , Mallefet Jerome
Published: July 2005

Nitric oxide synthase-like immunoreactivity (NOS-LI IR) was detected by immunohistochemistry in ventral light organs of the mesopelagic fish, Argyropelecus hemigymnus. Strong NOS-LI IR was present in nerve fibres and in other cells central for production or modulation of light:immunoreactive fibres surrounded the photophores, and were also present in the filter area. Filter cells, particularly in the outer layers, showed strong IR throughout the cytoplasm. Pharmacological studies suggested that nitric oxide(NO) modulates adrenaline-stimulated light emission, and that the modulation is correlated to the ability of the light organ to respond to adrenaline. Adrenaline is known to produce two different types of light response in isolated photophores from Argyropelecus: a slow, long-lasting, high intensity response, or a fast and weak response of short duration. Incubation of photophores in the NO donors sodium nitroprusside or S-nitroso-N-acetylpenicillamine prior to adrenaline stimulation reduced the intensity of the strong and long-lasting type of response, but had little or even a potentiating effect on the weakly responding photophores. Hydroxylamine, which is converted to NO if catalase activity is present in the tissue, reduced the duration and the intensity of the adrenaline response in all tested organs. The NOS-inhibitor l-thiocitrulline potentiated the adrenaline response in the weakly responding organs; the weaker the adrenaline effect, the stronger the potentiation caused by l-thiocitrulline. The strongly responding organs were instead inhibited by l-thiocitrulline. The results suggest that NO has an important role in the control of light emission from Argyropelecus hemigymnus photophores. The cGMP analogue dibutyryl cGMP, the guanylate cyclase inhibitor ODQ and the phosphodiesterase inhibitor pentoxiphylline had no effect, indicating that the NO effect does not involve cGMP.
Intraspecific variation of venom injected by fish-hunting Conussnails
Authors: Jakubowski Jennifer A. , Kelley Wayne P. , Sweedler Jonathan V. , Gilly William F. , Schulz Joseph R.
Published: July 2005

Venom peptides from two species of fish-hunting cone snails (Conus striatus and Conus catus) were characterized using microbore liquid chromatography coupled with matrix-assisted laser desorption/ionization-time of flight-mass spectrometry and electrospray ionization-ion trap-mass spectrometry. Both crude venom isolated from the venom duct and injected venom obtained by milking were studied. Based on analysis of injected venom samples from individual snails, significant intraspecific variation (i.e. between individuals) in the peptide complement is observed. The mixture of peptides in injected venom is simpler than that in the crude duct venom from the same snail, and the composition of crude venom is more consistent from snail to snail. While there is animal-to-animal variation in the peptides present in the injected venom, the composition of any individual's injected venom remains relatively constant over time in captivity. Most of the Conus striatus individuals tested injected predominantly a combination of two neuroexcitatory peptides (s4a and s4b),while a few individuals had unique injected-venom profiles consisting of a combination of peptides, including several previously characterized from the venom duct of this species. Seven novel peptides were also putatively identified based on matches of their empirically derived masses to those predicted by published cDNA sequences. Profiling injected venom of Conus catus individuals using matrix-assisted laser desorption/ionization-time of flight-mass spectrometry demonstrates that intraspecific variation in the mixture of peptides extends to other species of piscivorous cone snails. The results of this study imply that novel regulatory mechanisms exist to select specific venom peptides for injection into prey.
A year in the thermal life of a free-ranging herd of springbokAntidorcas marsupialis
Authors: Fuller Andrea , Kamerman Peter R. , Maloney Shane K. , Matthee André , Mitchell Graham , Mitchell Duncan
Published: July 2005

We used miniature data loggers implanted in the abdominal cavity to measure core body temperatures at 30 min intervals in eight (three males, five females) adult free-ranging springbok Antidorcas marsupialis in their natural habitat, over a period of 11–13 months. The animals were subjected to a nychthemeral range of air temperature that often exceeded 20°C, with an absolute minimum temperature of –6°C and a maximum of 34°C. Abdominal temperature exhibited a low amplitude (∼1.2°C)nychthemeral rhythm, with a temperature peak near sunset and a trough shortly after sunrise. The amplitude of the nychthemeral rhythm of body temperature was not correlated with the 24 h range of air temperature. Although mean 24 h body temperatures were positively correlated with corresponding air temperatures, mean daily body temperature increased, on average, by only 0.02°C per 1°C increase in air temperature, so that it was only∼0.3°C higher in summer than in winter. Mean monthly body temperatures were strongly positively correlated with photoperiod and, in parallel with changes in the time of sunrise, the times at which the minimum and maximum body temperatures occurred were shifted ∼1.2 h earlier in summer than in winter. Annual and daily variations in body temperature of springbok, like those of other free-living African ungulates, therefore appear to reflect an endogenous rhythm, entrained by the light:dark cycle, but largely independent of fluctuations in the environmental thermal load. Springbok exhibit remarkable homeothermy and do not employ adaptive heterothermy to survive in their natural environment.
Mechanical properties of the integument of the common gartersnake,Thamnophis sirtalis(Serpentes: Colubridae)
Authors: Rivera Gabriel , Savitzky Alan H. , Hinkley Jeffrey A.
Published: July 2005

The evolution of the ophidian feeding mechanism has involved substantial morphological restructuring associated with the ability to ingest relatively large prey. Previous studies examining the morphological consequences of macrophagy have concentrated on modifications of the skull and cephalic musculature. Although it is evident that macrophagy requires highly compliant skin, the mechanical properties of the ophidian integument have received limited attention, particularly in the context of feeding. We examined mechanical properties of skin along the body axis in Thamnophis sirtalis (Colubridae). Data were collected from tensile tests and were analyzed using a multivariate analysis of variance (MANOVA) and post-hoc multiple comparison tests. Significant differences in mechanical properties were detected among regions of the body. In general,prepyloric skin is more compliant than postpyloric skin, consistent with the demands of macrophagy.
Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses
Authors: Yancey Paul H.
Published: July 2005

Organic osmolytes are small solutes used by cells of numerous water-stressed organisms and tissues to maintain cell volume. Similar compounds are accumulated by some organisms in anhydrobiotic, thermal and possibly pressure stresses. These solutes are amino acids and derivatives,polyols and sugars, methylamines, methylsulfonium compounds and urea. Except for urea, they are often called `compatible solutes', a term indicating lack of perturbing effects on cellular macromolecules and implying interchangeability. However, these features may not always exist, for three reasons. First, some of these solutes may have unique protective metabolic roles, such as acting as antioxidants (e.g. polyols, taurine, hypotaurine),providing redox balance (e.g. glycerol) and detoxifying sulfide (hypotaurine in animals at hydrothermal vents and seeps). Second, some of these solutes stabilize macromolecules and counteract perturbants in non-interchangeable ways. Methylamines [e.g. trimethylamine N-oxide (TMAO)] can enhance protein folding and ligand binding and counteract perturbations by urea (e.g. in elasmobranchs and mammalian kidney), inorganic ions, and hydrostatic pressure in deep-sea animals. Trehalose and proline in overwintering insects stabilize membranes at subzero temperatures. Trehalose in insects and yeast,and anionic polyols in microorganisms around hydrothermal vents, can protect proteins from denaturation by high temperatures. Third, stabilizing solutes appear to be used in nature only to counteract perturbants of macromolecules,perhaps because stabilization is detrimental in the absence of perturbation. Some of these solutes have applications in biotechnology, agriculture and medicine, including in vitro rescue of the misfolded protein of cystic fibrosis. However, caution is warranted if high levels cause overstabilization of proteins.
Optical studies of nicotinic acetylcholine receptor subtypes in the guinea-pig enteric nervous system
Authors: Obaid A. L. , Nelson M. E. , Lindstrom J. , Salzberg B. M.
Published: July 2005

Nicotinic transmission in the enteric nervous system (ENS) is extensive,but the role of individual nicotinic acetylcholine receptor (nAChR) subtypes in the functional connectivity of its plexuses has been elusive. Using monoclonal antibodies (mAbs) against neuronal α3-, α4-,α3/α5-, β2-, β4- and α7-subunits, combined with radioimmunoassays and immunocytochemistry, we demonstrate that guinea-pig enteric ganglia contain all of these nAChR-subunits with the exception ofα4, and so, differ from mammalian brain. This information alone,however, is insufficient to establish the functional role of the identified nAChR-subtypes within the enteric networks and, ultimately, their specific contributions to gastrointestinal physiology. We have used voltage-sensitive dyes and a high-speed CCD camera, in conjunction with specific antagonists to various nAChRs, to elucidate some of the distinct contributions of the individual subtypes to the behaviour of enteric networks. In the guinea-pig,the submucous plexus has the extraordinary advantage that it is virtually two-dimensional, permitting optical recording, with single cell resolution, of the electrical activity of all of its neurones. In this plexus, the block of α3β2-, α3β4- and/or α7-nAChRs always results in a decrease in the magnitude of the synaptic response. However, the magnitude of the fast excitatory post-synaptic potentials (epsps) evoked by electrical stimulation of a neighbouring ganglion varies from cell to cell,reflecting the differential expression of subunits already observed using mAbs, as well as the strengths of the activated synaptic inputs. At the same time, we observe that submucous neurones have a substantial mecamylamine(Mec)-insensitive (non-nicotinic) component to their fast epsps, which may point to the presence of purinergic or serotonergic fast epsps in this system. In the myenteric plexus, on the other hand, the antagonist-induced changes in the evoked synaptic response vary depending upon the location of the stimulating electrode with respect to the ganglion under study. The range of activity patterns that follows sequential pharmacological elimination of individual subtypes suggests that nAChRs may be capable of regulating the activity of both excitatory and inhibitory pathways, in a manner similar to that described in the central nervous system.
Aquatic wing flapping at low Reynolds numbers: swimming kinematics of the Antarctic pteropod,Clione antarctica
Authors: Borrell Brendan J. , Goldbogen Jeremy A. , Dudley Robert
Published: July 2005

We studied swimming kinematics of the Antarctic pteropod, Clione antarctica, to investigate how propulsive forces are generated by flexible oscillating appendages operating at low Reynolds numbers(10<Re<100). We filmed ten ascending individuals at 125 frames s–1 from two orthogonal views, and reconstructed three-dimensional coordinates of the wing tip and body. Each half-stroke of flapping consisted of distinct power and recovery phases, which were of approximately equal duration in both the upstroke and the downstroke. As pteropods ascended, the body traced a sawtooth path when viewed laterally. The magnitude of these oscillations decreased with body mass, and larger animals(operating at Re>25) exhibited gliding during the recovery phase of each half-stroke. Maximum translational and rotational accelerations of the body occurred at the initiation of each power phase, suggesting that rotational circulation, the acceleration reaction, and wake recapture may all potentially contribute to vertical force production. Individual contributions of these mechanisms cannot, however, be assessed from these kinematic data alone. During recovery phases of each half-stroke, C. antarcticaminimized adverse drag forces by orienting the wings parallel to flow and by moving them along the body surface, possibly taking advantage of boundary layer effects. Vertical force production was altered through changes in the hydrodynamic angle of attack of the wing that augmented drag during the power phase of each half-stroke. At higher translational velocities of the body, the inclination of the power phase also became more nearly vertical. These results indicate that, in addition to serotonin-mediated modulation of wingbeat frequency reported previously in Clione, geometric alteration of wingbeat kinematics offers a precise means of controlling swimming forces.
Metabolic responses to cold in subterranean crustaceans
Authors: Issartel Julien , Renault David , Voituron Yann , Bouchereau Alain , Vernon Philippe , Hervant Frédéric
Published: July 2005

Changes in polyol, sugar and free amino acid (FAA) body contents were investigated in the aquatic, subterranean (i.e. hypogean) crustaceans Niphargus rhenorhodanensis and Niphargus virei and in a morphologically close aquatic, surface-dwelling (i.e. epigean) crustacean Gammarus fossarum acclimated to 12°C, 3°C and –2°C. With decreasing temperature, G. fossarum significantly increased its alanine and glutamine levels, while trehalose body content was found to increase above control levels only at –2°C. N. virei showed moderate increases of alanine and glycine, and no change in trehalose level was observed in this species. By contrast, N. rhenorhodanensis was the only species showing a significant rise in its total FAA pool, mainly explained by alanine, glycine, arginine and glutamine accumulations. This species also gradually increased its trehalose body content with decreasing temperature. Several cold-hardy ectotherms show metabolic responses to cold that are identical to those observed in N. rhenorhodanensis. A previous comparative study showed that the hypogean N. rhenorhodanensis exhibited a survival time (Lt50) at–2°C that was 26.3 times and 2.6 times higher than the hypogean N. virei and the epigean G. fossarum, respectively. Thus,crustacean levels of FAA and trehalose were correlated with their respective cold tolerances. Such differences in metabolic responses to cold in both hypogean organisms were unexpected since they both live in thermally buffered biotopes. Considering the current distribution areas of the two subterranean crustaceans studied, we assume that the cold hardiness found in the hypogean N. rhenorhodanensis could be correlated with its biogeography history during the quaternary glaciations.
Flow and conduit formation in the external fluid-transport system of a suspension feeder
Authors: von Dassow Michelangelo
Published: July 2005

To what extent is the development of a fluid-transport system related to flow within the system? Colonies of the bryozoan Membranipora membranacea have a simple external fluid-transport system with three components: the canopy of lophophores (crowns of ciliated tentacles), the edge of the canopy, and chimneys (raised openings in the canopy). The lophophores pump seawater into the colony and capture food particles from the seawater. The chimneys and canopy edge let the water back out of the colony. New chimneys form at the canopy edge as the colony grows. I tested whether there was a correlation between chimney formation and excurrent flow speed at the canopy edge by measuring excurrent flow speeds prior to chimney formation. Excurrent flow speeds were higher in regions that produced chimneys than in regions that did not form chimneys. Observations of changes in chimney shape after anesthetization with MgCl2 suggest that both growth and behavior determine chimney shape. Together, the results suggest that there is a strong correlation between growth and flow in this external fluid-transport system, with new chimneys forming at sites of high flow.
Substructural Multiobjective H∞ Controller Design for Large Flexible Structures: A Divide-and-Conquer Approach Based on Linear Matrix Inequalities
Authors: Toker O , Sunar M
Published: July 2005

In this paper, a novel substructural approach is proposed and successfully implemented for H∞ robust controller design for large flexible structures. It is assumed that sensors and actuators are discrete and located at some nodal points of the structure. In general, a finite element method (FEM)-based modelling approach results in a matrix differential equation of large dimensions. As the dimension becomes larger and larger controller design algorithms require more and more computation time, and start to have numerical problems. To cope with these difficulties, there are many known techniques in the literature, including the decentralized- and substructural-type methods. In this paper, a substructural-type approach based on the static condensation principle is adopted and the H∞ optimal controller design problem for large flexible structures is studied. The key point in the present approach is that the static condensation is performed in the abstract state space. Geometric information about the flexible structure is utilized in deciding how to do the state decomposition, then H∞ optimal controllers are designed at the substructure level, and finally a global controller is assembled for the whole structure. To improve the convergence of the algorithm, a multi-objective H∞ optimization approach is adopted. More precisely, while forcing the closed-loop poles to be in a given convex region to ensure fast dynamics, and hence improve the convergence of the substructural iterations, the H∞ objective function is minimized to achieve maximum robustness. The main advantage of this approach is that both the H∞ objective and the constraints on closed-loop poles can be expressed as a convex problem and formulated as linear matrix inequalities (LMIs), which can be solved easily, e.g. by LMI Toolbox of MATLAB. Overall, the proposed approach results in a reduction in computation time and improvements in numerical reliability as the problem of large size is decomposed into several smaller-size problems. The accuracy and effectiveness of the substructural H∞ control technique are tested on benchmark problems, and effects of structural non-linearities are studied.
Active Damping of Chatter in Machine Tools - Demonstration with a ‘Hardware-in-the-Loop’ Simulator
Authors: Ganguli A , Deraemaeker A , Horodinca M , Preumont A
Published: July 2005

The motivation of the work is twofold: (a) understand the physics behind regenerative chatter and the influence of structural damping and (b) demonstrate an active damping technique based on collocated actuator/sensor pairs. A numerical stability analysis is performed using the root locus method and it is shown that, along with the structural poles, eigenvalues due to the delay parameter may contribute to instability. Since experimental demonstration of chatter in real machines is difficult, an alternative way of demonstration via a mechatronic simulator is presented, using the ‘hardware-in-the-loop’ concept. The mathematical model of the regenerative cutting process in turning is simulated in a computer and this is interfaced to a beam, representing the structural dynamics of the machine, via a displacement sensor and force actuator. In this way, a hardware and a software loop are combined. In a second step, an additional control loop is added, consisting of an accelerometer sensor and a collocated inertial actuator. Numerical and experimental stability lobe diagrams are compared, with and without active damping.
Vibration Reduction of a Lightly Damped System Using a Hybrid Input Shaping Method
Authors: Kapucu S , Kaplan M , Bayseç S
Published: July 2005

This paper describes three different methods for generating a command profile for a lightly damped second-order system to manoeuvre it from one position to another, eliminating the residual vibrations likely to occur after the completion of the manoeuvre. The first method is a preshaped command input obtained by superimposing a cycloid onto a ramped versine + ramp function, and the second method is a reshaping of the input of any profile by convolving it with a sequence of two impulses. The third method, the ‘hybrid input method’, combines the first two methods to obtain a better robustness. The methods are tested on simulations, and the robustness of each is examined. The results show that the hybrid input shaping method is more robust to uncertainties in system parameters, namely the natural frequencies and damping ratio. The applicability of the methods is shown by experimental results.
Virtual Actuators with Virtual Sensors
Authors: Gawthrop P J
Published: July 2005

The virtual actuator approach to bond graph based control is extended to use virtual sensor inputs; this allows relative degree conditions on the controller to be relaxed. Furthermore, the effect of the transfer system can be eliminated from the closed-loop system. Illustrative examples are given.
A Study of Weaving ‘Turkish Knots’ in Handmade Carpets with an Electromechanical System
Authors: Topalbekiroğlu M , Kirecci A , Dülger L Canan
Published: July 2005

To form a Turkish knot in a handmade carpet, a study for a computer-controlled prototype loom and its drive system has been presented. The mechanisms involved in the prototype are described separately and the design considerations for each mechanism are given with the function requirements needed. The control of the knotting system is achieved with the actuators applied. The research on the subject is still continuing at the Department of Textile Engineering, University of Gaziantep.
An Improved Substructuring Control Strategy based on the Adaptive Minimal Control Synthesis Control Algorithm
Authors: Neild S A , Drury D , Stoten D P
Published: July 2005

The use of the minimal control synthesis (MCS) adaptive control algorithm in substructuring experiments is examined in this paper. Substructuring is a method of dynamically testing a system by splitting it into two parts, one of which contains the region of particular interest and is tested experimentally. The rest of the system is contained in the second part and is modelled numerically. These two parts interact in real-time to emulate the complete system. For an accurate representation of the whole system, control of the displacements imposed on the experimental test specimen is crucial. In this paper, the performance of the MCS algorithm at controlling an actuator used to impose the displacement on the experimental specimen is examined for a one-degree-of-freedom system. Based on these results, an improvement to the MCS control strategy is proposed and tested. Finally, a comparison between the modified MCS-based control strategy and a linear controller is conducted to demonstrate the potential advantage of this adaptive strategy.
Modelling and Simulation of a System of Mobile Service Units for the Large-Scale Event Industry
Authors: Othman F , Parkin R M
Published: July 2005

A proposed system of mobile service units (MSUs) is modelled and simulated for the mega-scale event of the Hajj, where millions of visitors move about in four nearby cities for about two weeks and the proposed MSUs will be transported accordingly to serve them. The model consists of subsystems that represent the master plan for the four cities, the event programme of the Hajj, the MSUs, the transportation system, and the control centre. Simulation results show that the proposed system can be modelled and the MSUs can be used successfully for the Hajj. Simulation results also show that a significant reduction in resources, compared with the fixed service centres currently in operation, can be achieved using the proposed MSUs.
Novel Water-soluble Light-emitting Materials Prepared by Noncovalently Bonded Self-assembly
Authors: Qiang Liang-Liang , Fan Qu-Li , Ma Zhun , Zheng Zhe , Wang Yun-Yun , Zhang Guang-Wei , Huang Wei
Published: July 2005

Novel noncovalently connected water-soluble nanoparticles containing hydroxyl-capped polyfluorene (PFOH) and poly(acrylic acid) (PAA) were obtained and characterized. These nanoparticles were quite stable in water and no precipitate was observed after weeks. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and laser light scattering (DLS) were used to confirm the morphology of the PFOH/PAA nanoparticles. Their optical properties were investigated and showed the similar optoelectronic properties with PFOH solid film.
Direct Synthesis and Intense Luminescence of Y2O3:Eu Nanophosphors by Complexation Combustion
Authors: Xia Guodong , Zhou Shengming , Zhang Junji , Wang Sumei , Xu Jun
Published: July 2005

In this paper, we report the synthesis of high-luminance Y2O3:Eu nanocrystal through a citrate–nitrate complexation combustion method at a low temperature of 200–280 °C. The as-combusted Y2O3:Eu phosphors are almost equiaxed crystallites with an average size of 30–40 nm, and have an intense red luminescence. The present fuel-deficient method suggests that by control of the ratio of citric acid to nitrates, it is valuable for the fabrication of Y2O3 nanoparticles without heat treatment. This process should be applicable to a wide range of nanocrystal oxides.
Microwave-assisted Preparation of Titanate Nanotubes
Authors: Wang Yan-an , Yang Jianjun , Zhang Jingwei , Liu Huijuan , Zhang Zhijun
Published: July 2005

Titanate nanotubes were successfully prepared for the first time by using microwave irradiation as the heating resource. The process is mild, quick, and easy to control. The morphology and structure of the product were checked by TEM, HRTEM and XRD.
Hydrothermal Synthesis of ZnO Long Fibers
Authors: Zhang Wuxing , Yanagisawa Kazumichi
Published: July 2005

ZnO fibers are synthesized by hydrothermal method from Zn(OH)42− starting solution. The morphologies of obtained ZnO fibers are closely related to the hydrothermal treatment temperature and Zn2+/OH− ratio, and the bunch-like growth phenomenon is revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Formation of Highly Reactive Species at the Interface Fe°–Iron Oxides Particles by Mechanical Alloying and Thermal Treatment: Potential Application in Environmental Remediation Processes
Authors: Moura Flávia Cristina Camilo , Oliveira Grazielli Cristina , Araujo Maria Helena , Ardisson José Domingos , Macedo Waldemar Augusto de Almeida , Lago Rochel Montero
Published: July 2005

In this work, the formation of highly reactive species at the interface of Fe°/iron oxides mixtures, i.e., Fe3O4, γ-Fe2O3, or α-Fe2O3 prepared by mechanical alloying and thermal treatment at 200–800 °C was studied. Mössbauer spectroscopic, XRD, SEM, BET, and magnetization measurements suggest a strong interaction between the metal and the oxides producing highly reactive surface species which can readily react with gas phases, i.e., O2, and with aqueous phase, i.e., H2O2, molecules.
Facile Fabrication of Nickel Oxide Hollow Spheres and Amorphous Carbon/Nickel Nanoparticles Composites Using Colloidal Carbonaceous Microspheres as Template
Authors: Zheng Mingbo , Cao Jieming , Chen Yongping , Ma Xianjia , Deng Shaogao , Tao Jie
Published: July 2005

Core/shell structure with colloidal carbonaceous microspheres as core and nanowhisker-like Ni(OH)2 as shell was synthesized by a facile precipitation method. NiO hollow spheres with hierarchical nanostructure and amorphous carbon/nickel nanoparticles composites were obtained by heat treatment in air and nitrogen, respectively. Nitrogen adsorption and desorption analysis indicated that these two novel products are both nanoporous materials with high specific surface area and large pore volume.
Colorless Transparent Fluorescence Material at the VUV Excitation: The Leached Sintered Glass with Impregnation of Tb3+ Ions
Authors: Liu Wei , Chen Danping , Miyoshi Hiroshi , Kadono Kohei , Akai Tomoko
Published: July 2005

First sample of VUV-excited intensely luminescent glass is successfully prepared using the leached sintered glass with impregnation of Tb3+ ions which is colorless, transparent and gives intense emission 5D4 → 7F5 at 543 nm under the 160 nm VUV excitation.
Soft Laser Desorption/Ionization Mass Spectrometry Using a Pyroelectric Ceramic Plate
Authors: Sato Hiroaki , Seino Teruyuki , Yamamoto Atsushi , Torimura Masaki , Tao Hiroaki
Published: July 2005

A novel matrix-free soft laser desorption/ionization mass spectrometry using a pyroelectric ceramic plate with a flat surface as an ionization platform was developed. Molecular-related ions of thermally unstable compounds such as peptides, oligosaccharides, and surfactants could be observed on the mass spectra with almost no fragmentation of the analytes.
Synthesis of Novel Dendritic α-Glycol Ligands Derived from Dl-Dithiothreitol and Their Application to Ring-opening Polymerization of ε-Caprolactone
Authors: Fujita Ken-ichi , Muraki Takahito , Sakurai Takayuki , Oishi Akihiro , Taguchi Yoichi
Published: July 2005

A series of dendritic ligands with an α-glycol core was synthesized through the coupling of Dl-dithiothreitol with poly(arylether) dendron in high yields. The corresponding aluminum dendrimers were applied as initiator to ring-opening polymerization of ε-caprolactone. A dendritic effect on the polydispersity (Mw/Mn) of poly(ε-caprolactone) was observed.
Estimation of Thermodynamic Parameters on Enantioselective Complexation Equilibria by Temperature-dependent FAB Mass Spectrometry
Authors: Shizuma Motohiro , Yamada Hitoshi , Takai Yoshio , Sawada Masami
Published: July 2005

The relative thermodynamic parameters, ΔΔG°enan(R/S), ΔΔH°enan(R/S), and ΔΔS°enan(R/S), on the enantioselective host–guest complexation equilibria were estimated easily using the temperature-dependent FAB mass spectrometry coupled with the enantiomer labeled guest method.
Novel Imidazolium-based Ionic Liquids with a Crown-ether Moiety
Authors: Liu Hui , Wang Han-zhi , Tao Guo-hong , Kou Yuan
Published: July 2005

A series of novel ionic liquids comprising crown-ether functionalities in cations or anions (crowned ionic liquids) have been prepared and characterized.
Ammonium Carboxylate-catalyzed [2,3]-Wittig Rearrangement of Silyl Enolates Generated from α-Allyloxy Esters
Authors: Sato Yoshinori , Fujisawa Hidehiko , Mukaiyama Teruaki
Published: July 2005

Silyl enolates that were generated from α-allyloxy esters afforded the corresponding [2,3]-Wittig rearrangement products in moderate to good yields on treatment with a catalytic amount of Lewis base such as tetrabutylammonium acetate or tetrabutylammonium 4-methoxybenzoate in DMF at room temperature.
The Importance of Lone Pair Electron Delocalization in the cis–trans Isomers of 1,2-Dibromoethenes
Authors: Yamamoto Takashi , Kaneno Daisuke , Tomoda Shuji
Published: July 2005

The subtle experimental energy difference between isomers of 1,2-dibromoethenes (0.090 ± 0.240 kcal mol−1) has been confirmed by high level MO calculations: the cis isomer is more stable by 0.04 kcal mol−1 than the trans isomer at the MP4(STDQ)/6-311++G(3df,3dp)//MP2/6-311++G(3df,3dp) level. It was strongly suggested that the most important origin of the cis-effect is the stabilizing hyperconjugative (charge-transfer) interaction of Br lone pairs with the πC=C* antibonding orbital.
Electric Field Effects on IR Absorption of α-Helical Polypeptide
Authors: Nakabayashi Takakazu , Ohta Nobuhiro
Published: July 2005

External electric field effects on the IR absorption spectrum of α-helical poly(γ-benzyl-l-glutamate) have been examined with electric field modulation spectroscopy. The electric-field-induced change in each vibrational band is reproduced by a superposition of the absorption spectrum, and its first and second derivative spectra, suggesting that the electric dipole moment and the molecular polarizability change following vibrational excitation. The N–H stretching band at 3291 cm−1 shows the largest change in the magnitude of dipole moment following vibrational excitation.
Synthesis of Well-isolated Barium Titanium Trioxide Nanocubes
Authors: Yan Tao , Shen Zhi-Gang , Chen Jian-Feng , Liu Xiao-Lin , Tao Xia , Yun Jimmy
Published: July 2005

Almost perfectly cubic shaped BaTiO3 nanocrystallites are generated by seed-mediated growth of BaTiO3 nanospheres, which are produced by a low-temperature aqueous synthetic method. The formation mechanism of the nanocubes is also proposed on the basis of dissolution–recrystallization mechanism.
Rapid Reversed-phase Separation Using Methacrylate-based C18 Monolithic Capillary Columns at High Flow Rates and Elevated Temperatures
Authors: Ueki Yuji , Umemura Tomonari , Iwashita Yoshikazu , Tsunoda Kin-ichi , Haraguchi Hiroki
Published: July 2005

Rapid reversed-phase separation in the time-scale of seconds was conducted using methacrylate-based C18 monolithic capillary columns at high flow rates and elevated temperatures. The reversed-phase monolithic columns were prepared by in situ polymerization of octadecyl methacrylate (ODMA) and ethylene dimethacrylate (EDMA) within the confines of a polyimide-coated fused silica capillary. When a mixture of isoamyl alcohol and 1,4-butandiol was employed as a porogenic solvent, highly permeable monolithic stationary phases with adequate separation efficiency were reproducibly produced. The pressure drops of 20 cm-long columns were typically below 0.4 MPa at a normal flow rate of 3 μL/min (linear velocity of 1 mm/s), and the theoretical plate numbers mostly reached 3000 plates/20 cm. These monolithic columns exhibited excellent mechanical strength as well as thermal stability, and they were properly operated even at a temperature of 80 °C and a high linear velocity of 100 mm/s. At 80 °C, the theoretical plate numbers exceeded 6000 plates/20 cm due to the enhanced mass transfer. Consequently, a series of alkylbenzenes, from toluene to amylbenzene, could be efficiently separated within 30 s on the 20 cm-long column by carrying out a ultra-high flow rate gradient at 80 °C.
Negative Ion Chemical Ionization Mass Spectra of C1–C6 n-Alkyl Nitrates
Authors: Sato Keiichi , Tanimoto Hiroshi , Imamura Takashi
Published: July 2005

Negative ion chemical ionization mass spectra were examined for C1–C6  n-alkyl nitrates. In contrast to peroxyacyl nitrates, NO3− ions were minor fragments. Major fragment ions were found to be NO2−, and [RO − H2]−, alkoxy counterparts from which two hydrogen atoms were eliminated. Relative intensity of the two fragment ions largely depends on the speciation, and the [RO − H2]−/NO2− ratio increases with the increasing carbon number.
Preparation of Fe3O4 Thin Films by a Chemical Bath Technique
Authors: Saito Yoichi , Kaga Kunitoshi , Tsutsumida Mei , Unuma Hidero
Published: July 2005

This letter describes a new method to prepare Fe3O4 thin films on glass substrates from aqueous solutions kept in a temperature range from 333 to 343 K. The process includes the deposition of precursor thin films, α-FeOOH, by oxidation of Fe2+ ion in aqueous solutions, and the conversion of the precursor to Fe3O4 in another solution. The film thickness, microstructure and magnetic properties of the resultant Fe3O4 thin films were characterized.
Radar‐duct and boundary‐layer characteristics over the area of The Gulf
Authors: Atkinson B. W. , Zhu M.
Published: July 2005

Radar‐duct characteristics and the associated atmospheric boundary layer over the The Gulf (50 ° N, 28 ° E) on 28 April 1996 were simulated with the NCAR–Penn State MM5V3 numerical model. The model was validated against meteorological observations and duct data gathered in a special observational programme. A benchmark study with horizontal grid‐length of 5 km revealed complete coverage of The Gulf by ducts throughout the whole twenty‐four hours. Over land, ducts existed only at night. Over The Gulf, meso‐β scale variation occurred: shallow (250 m) surface ducts existed within about 200 km of the north coast; elevated ducts, over 500 m deep, near the southern coast, and S‐shaped ducts (about 400 m deep) over the majority of the area. Duct strength also increased from north to south. These features were related to the marine internal boundary layer (MIBL) that formed over The Gulf in the ambient north‐west wind. Meso‐γ scale variations in duct‐top height occurred within 200 km of the north coast, immediately downwind of Qatar and off the central east and west coasts. Duct characteristics were influenced at the meso‐γ scale by coastal configuration and at the meso‐β scale by sea surface temperature (SST), land–sea temperature difference, orography and ambient wind. An increase in grid length to 25 km lost much of the meso‐γ scale structure but retained the meso‐β scale features. At the meso‐β scale, duct‐top height and strength were consistently lower in the sensitivity runs than those in the control run because of changes in the depth of the MIBL. Elimination of the north–south SST gradient resulted in a shallower and more stable MIBL. Maximizing the land–sea temperature difference increased the subsidence associated with the stronger sea‐breeze circulation in the sensitivity case and therefore decreased the depth of the MIBL. When the orography was much reduced the lower wind‐speeds in the sensitivity run were again associated with a shallower MIBL. The lower wind‐speeds resulted from the lack of the thermal‐wind effect induced by the high orography around much of The Gulf. The explicit reduction of the ambient wind also led to a reduction in depth of the MIBL. Duct type also changed in the sensitivity studies, surface ducts replacing S‐shaped ducts in those areas where the depth of the MIBL decreased. Of the meso‐β scale factors influencing the ducts, ambient wind speed was most important, closely followed by orography. The distribution of SST had the smallest effect. Copyright © 2005 Royal Meteorological Society.
Gravity wave drag estimation from global analyses using variational data assimilation principles. I: Theory and implementation
Authors: Pulido M. , Thuburn J.
Published: July 2005

A novel technique to estimate gravity wave drag from global‐scale analyses is presented. It is based on the principles of four‐dimensional variational data assimilation, using a dynamical model of the middle atmosphere and its adjoint. The global analyses are treated as observations. A cost function that measures the mismatch between the model state and observations is defined. The control variables are the components of the three‐dimensional gravity wave drag field, so that minimization of the cost function gives the optimal gravity wave drag field. The minimization is performed using a conjugate gradient method, with the adjoint model used to calculate the gradient of the cost function.

In this work, we present the theory behind the new technique and evaluate extensively the ability of the technique to estimate the gravity wave drag using so‐called twin experiments, in which the ‘observations’ are given by the evolution of the dynamical model with a prescribed gravity wave drag. The results show that the technique can estimate accurately the prescribed gravity wave drag. When the cost function is suitably defined, there is good convergence of the minimization scheme under realistic atmospheric conditions. We also show that the cost function gradient is well approximated taking into account only adiabatic processes. We note some limitations of the technique for estimating gravity wave drag in tropical regions if satellite temperature measurements are the only observational information available. Copyright © 2005 Royal Meteorological Society.
Neutral turbulent flow over forested hills
Authors: Ross A. N. , Vosper S. B.
Published: July 2005

Numerical simulations of neutral, turbulent flow over periodic forested hills are carried out using a first‐order turbulence closure scheme. The forest is represented by the inclusion in the model of a canopy near the surface where additional drag is exerted on the flow as a result of the trees. Simulations with a more traditional roughness‐length parametrization of the surface, which does not explicitly model the flow within the forest, are also carried out for comparison. Comparison of simulations with existing wind‐tunnel data shows that the simple mixing‐length canopy closure scheme provides a good estimate of the mean flow over a forested hill and is a significant improvement on a traditional roughness‐length parametrization in this case.

The numerical results are seen to be in close agreement with existing linear analytical solutions for flow over a low and wide forested hill. The model is used to investigate the breakdown of the analytical solution when the hill becomes steep and the perturbations to the flow are no longer linear. Even in the case of a gentle slope, the analytical solution can break down when the hill is narrow or the canopy is deep and the vertical velocities near the top of the canopy become large. This leads to a downwind shift in the surface pressure perturbation and an enhanced drag compared to a roughness‐length model. Model results also show enhanced flow separation in the presence of a canopy. These results are important for a range of meteorological problems including the interpretation of flux measurements, parametrization of orographic drag, predicting wind damage to trees and calculating the yield from wind turbines. © Royal Meteorological Society, 2005. S. B. Vosper's contribution is Crown copyright.