bluuebunny/crossref_metadata_2025_split huggingface dataset:
k-Opioid Receptors Behind the Blood-brain Barrier are Involved in the Anti-hypertensive Effects of Systemically Administered k-Agonists in the Conscious Spontaneously Hypertensive Rat
Authors: Shen S , Ingenito A J 
Published: October 2002

Abstract
We have shown previously that chronic intrahippocampal, intraperitoneal and subcutaneous administrations of non-peptide opioid receptor agonists induced depressor responses in the spontaneously hypertensive rat (SHR). However, it is not clear whether the hypotensive effect of systemic administration involves κ receptors behind the blood-brain barrier. In this study, the relative roles of central vs peripheral κ-opioid receptors in the hypotensive effect of κ-agonists was examined in conscious SHRs following chronic subcutaneous administration of two selective κ-agonists, BRL 52656 which freely penetrates the blood-brain barrier, and BRL 52974 which has only limited ability to do so.
Initial studies determined the dose-response relationship for each of the two drugs given intraperitoneally twice a day, while monitoring systolic arterial pressure (SAP), mean arterial pressure (MAP) and heart rate (HR) measured by the tail-cuff method. Both drugs caused biphasic arterial pressure responses, with lower doses of BRL 52656 causing depressor effects and higher doses resulting in pressor effects. By contrast, lower doses of BRL 52974 caused pressor effects and higher doses depressor effects. The biphasic effects occurred with BRL 52656 from 0.01 to 3.0 mg kg−1 and that for BRL 52974 from 0.1 to 30 mg kg−1. In subsequent studies the drugs were infused chronically, subcutaneously via osmotic minipumps over a 14-day period, BRL 52656 at 0.2 or 0.5 mg kg−1/day and BRL 52974 at 0.2 mg kg−1/day. At lower doses, BRL 52656 decreased SAP, MAP and HR but at higher doses only bradycardia was observed. BRL 52974 given chronically subcutaneously over 14 days had no significant effects on arterial pressure and decreased heart rate only after seven days of treatment.
Collectively, the results established that only the κ-agonist, which gained access to the central nervous system, lowered arterial pressure and heart rate, whereas the compound with limited ability to cross the blood-brain barrier was ineffective at equivalent doses. The complex dose-response pattern found with both drugs suggests that K-agonists have central hypotensive and bradycardic actions at low doses but at higher doses a mixture of both central and peripheral actions leads to hypertension and tachycardia.
Immunomodulatory Effect of Arctigenin, a Lignan Compound, on Tumour Necrosis Factor-α and Nitric Oxide Production, and Lymphocyte Proliferation
Authors: Cho Jae Youl , Kim Ae Ra , Yoo Eun Sook , Baik Kyong Up , Park Myung Hwan 
Published: October 2002

Abstract
We have investigated the immunomodulatory effects of arctigenin, a dibenzyl butyrolactone lignan compound, on tumour necrosis factor (TNF)-α and nitric oxide (NO) production, and lymphocyte proliferation.
Arctigenin inhibited strongly TNF-α production by lipopolysaccharide-stimulated murine macrophage RAW264.7 and differentiated human macrophage U937 with IC50 values of 5.0 and 3.9 μM, respectively, without displaying cytotoxicity. The TNF-α inhibitory effect of arctigenin in lipopolysaccharide-triggered RAW264.7 cells was increased by co-treatment with several known TNF-α inhibitors. It also potently attenuated T and B cell proliferation stimulated by concanavalin A and lipopolysaccharide in a dose-dependent manner with IC50 values of 2.9 and 14.6 μM, respectively. In contrast, the compound showed a different pattern in lipopolysaccharide- and interferon (IFN)-γ-induced NO production from RAW264.7 cells. Arctigenin inhibited NO release by IFN-γ signal, whereas it significantly enhanced lipopolysaccharide-triggered NO production in RAW264.7 cells.
The results suggested that arctigenin may regulate immune responses in activated macrophages and lymphocytes including TNF-α and NO production and lymphocyte proliferation.
Vibrational Energy Distribution of SiO Produced via the Chemical Activation of SiH3OH
Authors: Takahara Atsuko , Araki Ryuta , Tezaki Atsumu , Matsui Hiroyuki 
Published: October 2002

Abstract
Vibrationally excited SiO has been observed in the 193 nm photolysis of N2O/SiH4 mixtures with and without great excess of H2. While SiH4 + O(1D) (1) has been known to produce SiO in the mixture without H2, present kinetic analyses of SiO and OH indicate that SiH3 + OH (2) is responsible for the SiO production in the mixture with H2. The observed nascent vibrational distributions, approximated by Boltzmann distributions of Tv = 5200 ± 660 K for (1) and 2800 ± 790 K for (2), are reasonably accounted for by a statistical model assuming multi-step unimolecular decomposition of hot silanol.
A Correlation between Boiling Points and Refractive Indices of Organic Compounds : A Possible Role of Fluorine Atoms in Intermolecular Interactions
Authors: Katagiri Toshimasa , Uneyama Kenji 
Published: October 2002

Abstract
Correlations between boiling points and refractive indices of halogenated organic compounds are described. We note fair to excellent linear relationships between the boiling points of the compounds and the refractive indices.
Syntheses of Mycophenolic Acid and Its Analogs by Palladium Methodology
Authors: Lee Youngmin , Fujiwara Yasunari , Ujita Katsuji , Nagatomo Miki , Ohta Hiroshi , Shimizu Isao 
Published: October 2002

Abstract
Syntheses of mycophenolic acid (MPA, 1) and its analogs were carried out using palladium-catalyzed Heck carbonylation and olefination. Thus, the reaction of 2-bromo-3,5-dimethoxybenzyl alcohol (4) in toluene under carbon monoxide at 180 °C in the presence of palladium catalyst using sodium carbonate as a base gave 5,7-dimethoxyphthalide (5) in 88% yield. The phthalide 7 was converted to 6-iodo-5,7-dimethoxy-4-methylphthalide (8). Reaction of aromatic iodide 8 with isoprene and dimethyl malonate in the presence of palladium(0) catalyst gave the three component coupling product 9, which was converted into 1 in three steps. 4-NorMPA (16) and 4-homoMPA (22) were synthesized similarly.
Upper‐tropospheric flow transitions during rapid tropical cyclone intensification
Authors: Davidson Noel E. , Kar Sajal K. 
Published: October 2002

AbstractEvidence is presented of upper‐tropospheric flow transitions during rapid tropical cyclone (TC) intensification. Transitions occur when a mid‐latitude upper trough, with a wind maximum on its eastern flank, located well to the west of a storm, relaxes as anticyclogenesis occurs near to, and east of, its equatorward extremity. During these episodes, the flow is characterized by weak inertial stability. It is proposed that this allows extremely rapid and large‐scale changes to occur in the upper‐level environment of the storm. The new environment provides seemingly favourable conditions of reduced wind shear, development of a downstream trough very near the storm, and access for the storm outflow to the tropical easterlies and mid‐latitude westerlies.A global shallow‐water model, initialized with objective analyses at the 200 hPa level, is used to study the phenomenon, and the interaction between the environmental flow and local sources of mass and momentum. The sources are used to represent the effects of inner‐core deep convection in the outflow layer. Using the technique it seems possible, as a first approximation, to isolate the environment from the vortex development. It is shown that flow transitions are mostly independent of the presence of the TC. Short term, local enhancement of divergence over the TC occurs during superposition of environmentally‐induced divergence with the mass source. However, formation of the upper‐level vortex is the distinguishing feature of the intensification, and this occurs during an upper‐tropospheric flow transition. It is shown: (i) that the reduction in ventilation is associated with flow transitions, (ii) that these transitions directly influence the development of the upper vortex of the TC via downstream development of a weak environmental trough, and (iii) that the transitions indirectly influence the vortex development by allowing the momentum and mass sources to operate more efficiently to assist in both the development of the vortex and the outflow channels at small radii.Several examples of flow transitions during intensification are presented to support the proposed hypothesis. Copyright © 2002 Royal Meteorological Society.
Stratified flow over a mountain with a gap: Linear theory and numerical simulations
Authors: Zängl G. 
Published: October 2002

AbstractLinear theory and numerical simulations are used to investigate gap flows. Both gaps embedded in a long mountain ridge and gaps located between two isolated mountain peaks are considered. The study mainly focuses on level gaps so as to isolate three‐dimensional effects from two‐dimensional gravity‐wave propagation. Special attention is given to qualitative differences between the linear and the nonlinear flow regimes, the linear regime being defined by the absence of gravity‐wave breaking.In the linear regime, wind and pressure perturbations along a level gap axis are found to be qualitatively similar to those over a mountain ridge or peak, but of lower amplitude and longer horizontal wavelength. They are caused by vertically propagating gravity waves radiating from the mountain ridges (peaks) towards the gap axis and by low‐level confluence within the gap. In the nonlinear regime, however, these two processes are of minor importance due to upstream blocking and low‐level wave breaking. Instead, the pressure difference across the mountain ridge primarily drives the gap flow, which tends to be decoupled from the flow over the adjacent ridge. In contrast to the linear regime, gap winds are as strong as or even stronger than the winds over the mountain ridge. Surface friction is found to reduce the near‐surface wind speed more strongly for mountain ridges than for gaps. Copyright © 2002 Royal Meteorological Society.
Perspectives on the Future of Oil
Authors: Bentley R.W. , Booth R.H. , Burton J.D. , Coleman M.L. , Sellwood B.W. , Whitfield G.R. 
Published: October 2002

This paper assesses the risk of near-term oil shortages due to resource limits. Part I reviews the basics of the problem, including: • definitions, • broad quantities of oil available, • a simple model of how production develops from a group of fields, • actual production profiles of countries past peak. Part II examines the adequacy of the data available for estimating the total quantity of conventional oil, discussing separately: • the oil in reserves, • oil expected from reserves growth, and • oil yet-to-find. A contrast is made between the data used by the oil industry, and that available in the public domain. Part III outlines approaches taken by a variety of groups to model the future supply of oil. These groups include Campbell/Laherrère, the IEA, USGS, the EU, and some oil economists. Part IV presents oil production forecasts from a number of these groups for some specific countries; for the “Rest-of-the World”, and for the world as a whole. In Part V, the scope for non-conventional oil, and also gas, to offset a decline in conventional oil is examined. Finally, in Part VI, some wider implications of the situation are presented. The general arguments of the paper are: • It is useful to define conventional oil by recovery method. • Oil production in a region goes over peak when flow from new sources cannot compensate for the declining flow from existing sources. • Public domain reserves data hold only proved reserves, and contain serious errors. • Industry data are more reliable, and hold (proved + probable) reserves. • Much of ‘reserves growth’ is simply the increase from proved to (proved + probable). • The world's conventional oil ultimate is probably between 2,000 and 2,700 Gb. • But find rates are low, so peaking dates are not affected by high ultimates. The conclusions of the paper therefore are: • Non-OPEC oil production is currently close to its resource-limited peak. • The world's all-oil resource-limited peak is likely within about a decade. • These resource limits are likely to have serious economic and political repercussions.
Temperature/Pressure Changes Impact Hydrates from Coast to Slope, Northern Gulf of Mexico
Authors: Lowrie Allen , Moffett Susan , Jenkins Linda 
Published: October 2002

The northern Gulf of Mexico's passive margin is interrelated and synergistic with both regional and local inputs. Regional inputs may be thought of as deterministic and may include eustatic sea-level oscillations, sediment deposition from erosion of uplifted areas, climate above and below sea level, compression and dewatering of sediments once deposited, and related tectonics. The synergistic sum of these deterministic processes impacts the occurrence of natural gas and their hydrate phases. Along the foot of the continental slope, compression is transmitted to the sediment beneath and down-dip. Hydrates occur when suitable cold temperatures and high pressures are present. In water depths of ∼4 km, the hydrate stability zone (HSZ) may be up to 1 km thick. A prograding slope imparts regional pressures. Local pressures may be sufficient to catalyze the gas-to-hydrate phase change. Further compression may cause the zone to heat and/or to generate fractures, promoting hydrate disassociation and/or escape. The impact of a salt/shale lateral wedge or diapir (or both) entering the zone can be observed in several ways. Increased salinity raises the gaseous phase, thereby reducing hydrate existence. Increased heat also augments gaseousness. Note that shales dissipate heat and that the top of a salt diapir can be cool, even though overall salt is a heat conductor relative to sediments. Migrating salt/shale can promote fracturing, where the size and rate of migration determine the dimensions and frequency of fractures. As gases enterfractions, gas may expand and possibly block further gas entrance. Local sediment shattering and thermal anomalies could obviate the gas expansion effect. As the Louann Salt, which is located over the slope-sediment wedge, advances basinward, the amount of compression rises. Thus, temperatures and pressures change and the pattern of gases/hydrates are dynamic. Specific local predictions are subtle and may be regarded as probabilistic in model development. Equal subtlety is experienced along the ocean/land contact. Hydrate existence is determined by gas chemistry, whether methane or ethane is present. As the sea level oscillates, temperatures and pressures also oscillate. Landward, the HSZ limit during sea-level highs is disassociated, and a new, more basinward HSZ is established. Specific landward HSZ limit is determined by the gas chemistry.
Energy Exploitation of Agricultural Residues in Crete
Authors: Vamvuka D. , Tsoutsos T.D. 
Published: October 2002

The island of Crete is a typical Mediterranean area with a high biomass potential, the major part of which is still unexploited or irrationally exploited, but at the same time has a problematic energy supply during the high touristic season. In this paper the energy content of the biomass potential is estimated, as a parameter to alleviate the energy system of the island. The exploitation of biomass is studied with reference to the following aspects: The major residue production (olive kernel, husks – citrus fruits, grapes), branches (olive tree, citrus tree, grape tree); The qualitative analysis (proximate, ultimate, calorific value, ash analysis) of samples of basic agricultural residues of the Cretan production (vineshoots, olive tree wood and citrus, olive kernel).
Removal of Pollutants from Water Using Untreated and Treated Sawdust and Water Hyacinth
Authors: El-Nabarawy Th. , Khedr S.A. 
Published: October 2002

Sawdust and water hyacinth are waste products which have no economical application in Egypt. They even constitute a solid waste as far as the environment is concerned. As-received sawdust and water hyacinth were treated with phosphoric acid, phosphoric acid + urea or phosphoric acid + urea + dimethylformamide. The as-received and treated samples were used for the removal of Methylene Blue, iodine, phenol and ammonia from their aqueous solutions. The optimum conditions for the maximum adsorption of each pollutant were determined. The isotherms obtained obeyed the Freundlich and Langmuir equations in a satisfactory manner. The initial stages of adsorption follow first-order kinetics as predicted from the Lagergren equation. Sawdust and water hyacinth show promising potentialities for the removal of pollutants from water and can, at least, be used as precursors for the preparation of efficient adsorbents for the removal of pollutants from water.
Investigation into the Use of Macroporous Anion Exchangers for the Sorption and Separation of Iminodiacetate Complexes of Lanthanum(III) and Neodymium(III)
Authors: Hubicka Halina , Kolodyńska Dorota 
Published: October 2002

Rare earth element complexes with iminodiacetic acid (IMDA) of the Ln(IMDA)−2 type exhibit an unusual sequence of affinities for anion exchangers. In this work, the applicability of strongly basic gel and macroporous polystyrene anion exchangers to the sorption and separation of rare earth element complexes with iminodiacetic acid has been investigated. It was shown that the acetate forms of both the macroporous and gel anion exchangers were most effective and cheapest for this type of separation. As far as their applicability to the purification of lanthanum(III) IMDA from the corresponding neodymium(III) complexes is concerned, the anion exchangers investigated may be arranged in the following sequence: strongly basic gel anion exchangers ≈ strongly basic macroporous anion exchangers > weakly basic macroporous anion exchangers.
Removal of Ni2+ and Cu2+ Ions from Aqueous Solution on to Lignite-Based Carbons
Authors: Samra S.E. 
Published: October 2002

Non-activated lignites were prepared by the carbonization of Egyptian lignite in a limited quantity of air at 500°C, 700°C and 900°C, respectively. Zinc chloride-activated carbons were also prepared by the carbonization of lignite with 20 wt%, 40 wt% and 60 wt% zinc chloride in a limited quantity of air at 600°C. The surface areas of the resulting samples were determined from nitrogen adsorption studies at 77 K and from carbon dioxide adsorption studies at 298 K. The functional acidic groups on the surface were determined by neutralization with aqueous solutions of NaHCO3, Na2CO3 and NaOH, respectively. The sorption of Ni2+ and Cu2+ ions on the prepared carbons as well as on the as-received lignite (L) were investigated. The influence of the time of contact, the initial ion concentration and the temperature was studied and the kinetics of the process were investigated. Equilibrium sorption isotherms were determined and the results interpreted by applying the Freundlich and Langmuir equations. The surface area was found to generally increase with increasing carbonization temperature. For activated carbons, the surface area increased with an increase in the amount of zinc chloride used in the activation process. The chemisorption of Ni2+ and Cu2+ ions on lignite-based carbon was found to be a pseudo-second order process. The acid sites on the surface provide active sites for the chemisorption of Ni2+ and Cu2+ ions and a qualitative relationship was found to exist between the maximum sorption capacity of these metal ions and the total surface acidity.
Analysis of the Potentiometric Titration Curves of Weakly Basic Anionites
Authors: Mamchenko A.V. , Chernova L.G. 
Published: October 2002

An analysis of the experimental potentiometric titration curves for various classes of weakly basic anionites has been made from the basis of the exchange equilibrium theory. When the NaCl concentration in the external solution differed by more than two orders of magnitude, two curves were obtained for each ionite. Reference to the activities of the chloride ions allowed these two curves to be combined satisfactorily. The acrylic anionite, Amberlite IRA 67, fulfilled the model of ideal exchange in the gel phase. Systematic deviations from such ideal behaviour were observed for the polystyrene–divinylbenzene anionite, Lewatit MP 62, while the experimental data for Lewatit AP 49 exhibited an essential deviation from a linear dependence when plotted in terms of the extended Henderson–Hasselbalch equation. Comparative analyses of the titration curves for weakly basic Amberlite IRA 67, strongly basic AB 17-8 and Lewatit AP 49 anion exchangers led to the suggestion that Lewatit AP 49 contained weak and strong basic groups whose behaviour may be described by the extended Henderson–Hasselbalch equation using various effective equilibrium constants but the same value of n (= 1). An equation for calculating the quantity of strong and weak basic groups in an acrylic anionite has been obtained. An explanation of ideality in terms of weakly dissociating (basic) and strongly dissociating (salt) resinates of weakly basic acrylic anion-exchange resins has been proposed.
Physicochemical and Catalytic Properties of Vanadia/Titania Catalysts. III. Acidic Properties
Authors: El-Nabarawy Th. , Alaya M.N. , Ahmed S.A. Sayed , Youssef A.M. 
Published: October 2002

FT-IR spectral studies of titania calcined at 400°C or 600°C indicated the presence of four important absorption bands with maxima located at 1630, 2920, 3670 and 3740 cm−1, respectively. These absorption bands have been ascribed to undissociated, coordinated water, hydrogen-bonded OH, acidic OH and basic OH groups, respectively. For vanadia/titania samples containing 6 wt% and 12 wt% V2O5 calcined at 400°C or 600°C, the band at 1630 cm−1 still existed in the corresponding spectra whereas that at 2920 cm−1 disappeared, thereby indicating an interaction between the vanadia and the hydrogen-bonded OH groups. The FT-IR spectra of pyridine adsorbed on to titania or titania/vanadia samples exhibited bands at 1420 cm−1 and 1540 cm−1, respectively, the former being ascribed to Lewis acidity and exhibiting a shift to lower wavenumbers with increasing vanadia content, while the latter was ascribed to the presence of Brönsted acid sites. Temperature programmed desorption (TPD) of pyridine from titania exhibited three desorption peaks extending over the temperature ranges 267–288°C, 335–370°C and 480–510°C, respectively. Impregnation of the initial titania samples with vanadia led to an increase in both the amount of acid sites present on the surfaces of the samples and in the acid strength. Besides reacting with Brönsted and Lewis acid sites, pyridine also underwent hydrogen bonding, with the hydrogen atom serving as a bridge between two electronegative nitrogen atoms.