bluuebunny/crossref_metadata_2025_split huggingface dataset:
Norbornane Mimics of Distorted β‐D‐Glucopyranosides – Inhibitors of β‐D‐Glucopyranosidases?
Authors: Buser Stephan , Vasella Andrea 
Published: April 2006

AbstractThe racemic gluco‐configured norbornanes 4 and 16 were prepared and tested as inhibitors of β‐glucosidases. The known alcohol 5 was deprotected to provide the triol 6. Silylation (→ 7), monobenzoylation (→ 8/9), and oxidation provided the regioisomeric ketones 10 and 11. Reduction of 10 gave the desired endo‐alcohol 13, albeit in low yield, while reduction of the isomeric ketone 11 provided mostly the altro‐configured endo‐alcohol 12. The alcohol 13 was desilylated to 14. Debenzoylation to 15 followed by hydrogenolytic deprotection gave the amino triol 4 that was reductively aminated to the benzylamine 16. The amino triols 4 and 16 proved weak inhibitors of the β‐glucosidase from Caldocellum saccharolyticum (4: IC50 = 5.6 mm; 16: IC50 = 3.3 mm) and from sweet almonds (16: IC50 = 5.5 mm). A comparison of 4 with the manno‐configured norbornane 3 shows that 3 is a better inhibitor of snail β‐mannosidase than 4 is of β‐glucosidases, in keeping with earlier results suggesting that these β‐glycosidases enforce a different conformational itinerary.
Separation of triacylglycerols in a complex lipidic matrix by using comprehensive two‐dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection
Authors: Dugo Paola , Kumm Tiina , Chiofalo Biagina , Cotroneo Antonella , Mondello Luigi 
Published: April 2006

AbstractThe present investigation describes the employment of a comprehensive 2‐D HPLC system, based on the combination of a silver ion and an RP column, for the characterization of the triacylglycerol (TAG) fraction of a very complex lipidic sample: donkey milk fat. The TAGs were grouped on the resulting bidimensional contour plot according to their double bond numbers (aligned along vertical bands) and according to their partition numbers (aligned along horizontal bands). Peak assignment was supported by using atmospheric pressure chemical ionization mass spectrometric (APCI‐MS) detection. The combination of the enhanced resolving power of comprehensive multidimensional LC, the formation of ordered 2‐D patterns, and APCI‐MS detection proved to be an effective tool for the characterization of the complex matrix, enabling the separation and identification of nearly 60 TAGs.
On the nature of unsteady three-dimensional laminar boundary-layer separation
Authors: Williams James C. 
Published: April 2006

Solutions have been obtained for a family of unsteady three-dimensional boundary-layer flows which approach separation as a result of the imposed pressure gradient. These solutions have been obtained in a co-ordinate system which is moving with a constant velocity relative to the body-fixed co-ordinate system. The flows studied are those which are steady in the moving co-ordinate system. The boundary-layer solutions have been obtained in the moving co-ordinate system using the technique of semi-similar solutions. The behaviour of the solutions as separation is approached has been used to infer the physical characteristics of unsteady three-dimensional separation.In the numerical solutions of the three-dimensional unsteady laminar boundary-layer equations, subject to an imposed pressure distribution, the approach to separation is characterized by a rapid increase in the number of iterations required to obtain converged solutions at each station and a corresponding rapid increase in the component of velocity normal to the body surface. The solutions obtained indicate that separation is best observed in a co-ordinate system moving with separation where streamlines turn to form an envelope which is the separation line, as in steady three-dimensional flow, and that this process occurs within the boundary layer (away from the wall) as in the unsteady two-dimensional case. This description of three-dimensional unsteady separation is a generalization of the two-dimensional (Moore-Rott-Sears) model for unsteady separation.
Turbulent buoyant convection from a source in a confined region
Authors: Manins P. C. 
Published: April 2006

An extension of the model first proposed by Baines & Turner (1969) is derived with careful attention to the conditions required for its application. The most important of these are that the Prandtl number ν/kis of order unity or greater, the ratio of the lengthLto depthHof the region is greater than about 1·2 for the two-dimensional region considered andRis so large thatR[gsim ]L/HandR[Gt ] 1/α. The characteristic group\[ R\equiv \alpha^{\frac{2}{3}}F_0^{\frac{1}{3}}H/\nu. \]R2is a Grashof number based on the source strengthF0of the buoyant convection which is modelled using turbulent plume theory and the entrainment constant α, the ratio of inflow velocity across the edge of the plume to mean local plume velocity. The conditions onRensure that the source of buoyant convection is the dominant transportive mechanism in the region and the restrictions on the aspect ratio ensure that there is clear separation between the passive motions in the bulk of the region and the intense highly confined buoyant convection.The manner in which the convective fluid recirculates to become part of the passive interior is studied and shown to be controlled by the same dynamics as fluid intrusion into a stably stratified environment.Several new solutions are obtained, including cases of steady conditions involving only one source.
The distortion of turbulence by a circular cylinder
Authors: Britter R. E. , Hunt J. C. R. , Mumford J. C. 
Published: April 2006

The flow of grid-generated turbulence past a circular cylinder is investigated using hot-wire anemometry over a Reynolds number range from 4·25 × 103 to 2·74 × 104 and a range of intensities from 0·025 to 0·062. Measurements of the mean velocity distribution, and r.m.s. intensities and spectral energy densities of the turbulent velocity fluctuations are presented for various radial and circumferential positions relative to the cylinder, and for ratios of the cylinder radius a to the scale of the incident turbulence Lx ranging from 0·05 to 1·42. The influence of upstream conditions on the flow in the cylinder wake and its associated induced velocity fluctuations is discussed.For all measurements, detailed comparison is made with the theoretical predictions of Hunt (1973). We conclude the following.
The amplification and reduction of the three components of turbulence (which occur in different senses for the different components) can be explained qualitatively in terms of the distortion by the mean flow of the turbulent vorticity and the ‘blocking’ or ‘source’ effect caused by turbulence impinging on the cylinder surface. The relative importance of the first effect over the second increases as a/Lx increases or the distance from the cylinder surface increases.Over certain ranges of the variables involved, the measurements are in quantitative agreement with the predictions of the asymptotic theory when a/Lx [Lt ] 1, a/Lx [Gt ] 1 or |k| a [Gt ] 1 (where k is the wavenumber).The incident turbulence affects the gross properties of the flow in the cylinder wake, but the associated velocity fluctuations are probably statistically independent of those in the incident flow.The dissipation of turbulent energy is greater in the straining flow near the cylinder than in the approach flow. Some estimates for this effect are proposed.
Experiments on an aerofoil at high angle of incidence in longitudinal oscillations
Authors: Maresca C. , Favier D. , Rebont J. 
Published: April 2006

Details of flow visualization, aerodynamic forces and pitching moment, static pressure and skin friction measurements have been carried out on a symmetrical aerofoil at fixed angle of incidence in longitudinal oscillations parallel to the uniform airstream of a wind-tunnel.This investigation shows weak unsteady effects at incidences below that of static stall. For higher incidences, strong unsteady effects appear and depend on the frequency and amplitude of the oscillations. The measurements indicate an overshoot of the instantaneous lift and drag which is explained by a strong vortex shedding process occurring during the dynamic stall encountered by the aerofoil in decelerated motion, as observed for profiles oscillating in pitch through stall. When the aerofoil is going forward in accelerated motion dynamic reattachment may be observed at very high incidence over a short part of the period of oscillation.Dynamic stall and dynamic reattachment contribute to a favourable effect of unsteadiness on the mean lift coefficient, which increases as compared to the steady state one, and which is expressed through an empirical formula involving incidence, frequency and amplitude of oscillations. At given incidence, optimization of this feature is achieved by matching the frequency and the amplitude of oscillation, respectively with the frequency linked with the highest peak of energy in the wake, and with the distance between two consecutive vortices in the mean wake when modelled as a von Kármán's vortex street.
A high-order cnoidal wave theory
Authors: Fenton J. D. 
Published: April 2006

A method is outlined by which high-order solutions are obtained for steadily progressing shallow water waves. It is shown that a suitable expansion parameter for these cnoidal wave solutions is the dimensionless wave height divided by the parameter m of the cn functions: this explicitly shows the limitation of the theory to waves in relatively shallow water. The corresponding deep water limitation for Stokes waves is analysed and a modified expansion parameter suggested.Cnoidal wave solutions to fifth order are given so that a steady wave problem with known water depth, wave height and wave period or length may be solved to give expressions for the wave profile and fluid velocities, as well as integral quantities such as wave power and radiation stress. These series solutions seem to exhibit asymptotic behaviour such that there is no gain in including terms beyond fifth order. Results from the present theory are compared with exact numerical results and with experiment. It is concluded that the fifth-order cnoidal theory should be used in preference to fifth-order Stokes wave theory for wavelengths greater than eight times the water depth, when it gives quite accurate results.
Vortex pairing in a circular jet under controlled excitation. Part 1. General jet response
Authors: Zaman K. B. M. Q. , Hussain A. K. M. F. 
Published: April 2006

Hot-wire and flow-visualization studies have been carried out in three air jets subjected to pure-tone acoustic excitation, and the instability, vortex roll-up and transition as well as jet response to the controlled excitation have been investigated. The centreline fluctuation intensity can be enhanced by inducing stable vortex pairing to a level much higher than even that at the ‘preferred mode’, but can also be suppressed below the unexcited level under certain conditions of excitation. The conditions most favourable to vortex pairing were determined as a function of the excitation Strouhal number, the Reynolds number (ReD), and the initial shear-layer state, i.e. laminar or turbulent. It is shown that the rolled-up vortex rings undergo pairing under two distinct conditions of excitation: ‘the shear layer mode’ when the Strouhal number based on the initial shear-layer momentum thickness (Stθ) is about 0·012, and ‘the jet column mode’ when the Strouhal number based on the jet diameter (StD) is about 0·85. The former involves pairing of the near-exit thin vortex rings when the initial boundary layer is laminar, irrespective of the value of StD. The latter involves pairing of the thick vortex rings at x/D ≅ 1·75, irrespective of Stθ or whether the initial boundary layer is laminar or turbulent. For laminar exit boundary layer, pairing is found to be stable, i.e., occurring regularly in space and time, for ReD < 5 × 104, but becomes intermittent with increasing ReD or fluctuation intensity in the initial boundary layer.The trajectories of the vortex centres and their convection velocities during a pairing event have been recorded through phase-locked measurements. In the presence of stable vortex pairing, the time average profiles of fluctuation intensities and Reynolds stress show noticeable deviations from those in the unexcited jet. The vortex pairing phenomenon produce considerably larger excursions of the $\widetilde{uv}(t)$ signal than the time-average Reynolds stress reveals, suggesting that only certain phases of the pairing process may be important in entrainment, and production of Reynolds stress and jet noise.
Visualization of actin cytoskeletal dynamics during the cell cycle in tobacco (Nicotiana tabacum L. cv Bright Yellow) cells
Authors: Yu Miaomiao , Yuan Ming , Ren Haiyun 
Published: April 2006

Background information. The actin cytoskeleton forms distinct actin arrays which fulfil their functions during cell cycle progression. Reorganization of the actin cytoskeleton occurs during transition from one actin array to another. Although actin arrays have been well described during cell cycle progression, the dynamic organization of the actin cytoskeleton during actin array transition remains to be dissected.Results. In the present study, a GFP (green fluorescent protein)‐mTalin (mouse talin) fusion gene was introduced into suspension‐cultured tobacco BY‐2 (Nicotiana tabacum L. cv Bright Yellow) cells by a calli‐cocultivation transformation method to visualize the reorganization of the actin cytoskeleton in vivo during the progression of the cell cycle. Typical actin structures were indicated by GFP—mTalin, such as the pre‐prophase actin band, mitotic spindle actin filament cage and phragmoplast actin arrays. In addition, dynamic organization of actin filaments was observed during the progression of the cell from metaphase to anaphase. In late metaphase, spindle actin filaments gradually shrank to the equatorial plane along both the long and short axes. Soon after the separation of sister chromosomes, actin filaments aligned in parallel at the cell division plane, forming a cylinder‐like structure. During the formation of the cell plate, one cylinder‐like structure changed into two cylinder‐like structures: the typical actin arrays of the phragmoplast. However, the two actin arrays remained overlapping at the margin of the centrally growing cell plate, forming an actin wreath. When the cell plate matured further, an actin filament network attached to the cell plate was formed.Conclusions. Our results clearly describe the dynamic organization of the actin cytoskeleton during mitosis and cytokinesis of a plant cell. This demonstrates that GFP—mTalin‐transformed tobacco BY‐2 cells are a valuable tool to study actin cytoskeleton functions in the plant cell cycle.
Intracellular degradation of insulin and crinophagy are maintained by nitric oxide and cyclo‐oxygenase 2 activity in isolated pancreatic islets
Authors: Sandberg Monica , Borg L.A. Håkan 
Published: April 2006

Background information. Pancreatic β‐cells require an optimal insulin content to allow instantaneous secretion of insulin. This is maintained by insulin biosynthesis and intracellular degradation of insulin. Degradation may be effected by crinophagy, i.e. the fusion of secretory granules with lysosomes. IL‐1β (interleukin 1β) induces distinct changes of β‐cell lysosomes. To study the mechanisms for intracellular insulin degradation and crinophagy, isolated mouse pancreatic islets were exposed to IL‐1β and known pathways for IL‐1β actions were blocked. Intracellular insulin degradation was determined by following the fate of radioactively labelled insulin. Crinophagy was studied by ultrastructural analysis. The effects of blocking pathways for IL‐1β were monitored by measurements of nitrite and PGE2 (prostaglandin E2).Results. IL‐1β caused an enhancement of islet intracellular insulin degradation and an increase in the lysosomal incorporation of β‐cell secretory granules. The effects of IL‐1β were abolished by aminoguanidine, a selective inhibitor of inducible NOS (nitric oxide synthase), or by rofecoxib, a specific inhibitor of COX‐2 (cyclo‐oxygenase 2). In the absence of IL‐1β, nitroarginine, which is a selective inhibitor of constitutive NOS, caused a decrease in intracellular degradation of insulin in parallel with a decreased production of NO and PGE2 by the islets.Conclusions. The correlation between the enhanced intracellular insulin degradation and lysosomal changes caused by IL‐1β suggests that insulin degradation may be effected by crinophagy. Under physiological conditions, significant β‐cell degradation of insulin may depend on the activity of COX‐2, possibly stimulated by endogenous NO.
Angioma serpiginosum: Dermoscopy for diagnosis, pulsed dye laser for treatment
Authors: İLKNUR Turna , FETIL Emel , AKARSU Sevgi , ALTINER Didem Didar , ULUKUŞ Çağnur , GÜNEŞ Ali Tahsin 
Published: April 2006

ABSTRACTAngioma serpiginosum is a rare benign vascular disorder, characterized clinically by multiple minute, red to purple, grouped macules in serpiginous and gyrate patterns and histopathologically by ectatic dilatation of capillaries. Patients can undergo unnecessary hematological tests, because the condition can be confused with chronic purpuric dermatoses. An 18‐year‐old man with angioma serpiginosum of his left arm was evaluated by dermoscopy and treated with pulsed dye laser. Numerous small, relatively well‐demarcated, round to oval red lagoons were determined with dermoscopy, and approximately 75% of the area of his lesion disappeared after four sessions of pulsed dye laser. Our case supports the hypothesis that dermoscopy is beneficial in the diagnosis of angioma serpiginosum and that pulsed dye laser is effective in the treatment of this disorder.
Effect of Bacillus licheniformis and Bacillus subtilis Supplementation of Ewe's Feed on Sheep Milk Production and Young Lamb Mortality
Authors: Kritas S. K. , Govaris A. , Christodoulopoulos G. , Burriel A. R. 
Published: April 2006

SummaryThe purpose of this pilot study was to evaluate under field conditions the effect of a probiotic containing Bacillus licheniformis and Bacillus subtilis on young lamb mortality and sheep milk production when administered in the late pregnancy and lactation feed of ewes. In a sheep farm, two groups of milking ewes with identical genetic material, management, nutrition, health status and similar production characteristics were formed. One group (46 ewes) served as control, while the other one (48 ewes) served as a probiotic‐treated group. Both groups of ewes received a similar feeding regiment, but the ewes of the second group were additionally offered a probiotic product containing B. licheniformis and B. subtilis (BioPlus 2B, Chr. Hansen, Denmark) at the approximate dose of 2.56 × 109 viable spores per ewe per day. Lamb mortality during the 1.5 months suckling period, and milk yield during the 2 months of milk collection for commercial purposes have been recorded. In the non‐treated control group, 13.1% mortality was observed versus 7.8% in the probiotic‐treated group (P = 0.33), with mortality being mainly due to diarrhoea. Microbiological examination of diarrhoeic faeces from some of the dead lambs in both groups revealed the presence of Escherichia coli. The average daily milk yield per ewe was significantly lower in the control group (0.80 l) than that in the probiotic‐treated group (0.93 l) (P < 0.05). Fat and protein content of milk in ewes that received probiotics was significantly (P < 0.05) increased compared with untreated ewes. It was concluded that supplementing ewe's feed with probiotics may have beneficial effect on subsequent milk yields, fat and protein content.
Chlorophyll fluorescence technique as a rapid diagnostic test of the effects of the photosynthetic inhibitor chlorotoluron on two winter wheat cultivars
Authors: KORRES N E , FROUD‐WILLIAMS R J , MOSS S R 
Published: April 2006

SummaryA modified chlorophyll fluorescence technique was evaluated as a rapid diagnostic test of the susceptibility of wheat cultivars to chlorotoluron. Two winter wheat cultivars (Maris Huntsman and Mercia) exhibited differential response to the herbicide. All of the parameters of chlorophyll fluorescence examined were strongly influenced by herbicide concentration. Additionally, the procedure adopted here for the examination of winter wheat cultivar sensitivity to herbicide indicated that the area above the fluorescence induction curve and the ratio FV/FM are appropriate chlorophyll fluorescence parameters for detection of differential herbicide response between wheat cultivars. The potential use of this technique as an alternative to traditional methods of screening new winter wheat cultivars for their response to photosynthetic inhibitor herbicide is demonstrated here.
ANALYSIS OF PARABOLIC PROBLEMS ON PARTITIONED DOMAINS WITH NONLINEAR CONDITIONS AT THE INTERFACE: APPLICATION TO MASS TRANSFER THROUGH SEMI-PERMEABLE MEMBRANES
Authors: CALABRÒ FRANCESCO , ZUNINO PAOLO 
Published: April 2006

In this work we address a problem governed by linear parabolic partial differential equations set in two adjoining domains, coupled by nonlinear interface conditions of Neumann type. In particular, we address the existence and uniqueness of strong solutions by applying the strong maximum principle, the Schauder fixed point theorem and the fundamental solutions of linear parabolic partial differential equations. In the first part of this work, we consider the properties of a linear parabolic partial differential equation set on a single domain with a nonlinear boundary condition. After having addressed the well-posedness and some comparison results for the problem on one domain, in the second part of this work we address the case of coupled problems on adjoining domains. In both cases, we complete the understanding of the behavior of the solution of the problems at hand by means of numerical simulations. The theoretical results obtained here are applied to study the behavior of a biological model for the transfer of chemicals through thin biological membranes. This model represents the dynamics of the concentration u of a chemical solution separated from the exterior by a semi-permeable membrane. The analysis of the two-domain problem that we carry out could also be used to investigate the convergence property of iterative substructuring methods applied to the approximation of multidomain problems with nonlinear coupling of Neumann type.