bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass loss and blunting during high-speed penetration
Authors: Davis R N , Neely A M , Jones S E 
Published: September 2004

A new analytical model of high-speed friction was developed to account for the observed velocity dependence in sliding friction at high speeds and was successfully applied to the analysis of data previously reported by Jones et al. for a number of concrete penetration tests using ogive-nose projectiles of high-strength steel alloy. The model permitted very consistent predictions of penetrator performance and target strength based on the experimental data. The subsequent development by Davis et al. of a stepwise incremental approximation to the velocity-dependent coefficient of sliding friction simplified the implementation of the model, while preserving the quality of the linear approximation to the assumed velocity dependence in sliding friction at high speeds. The stepwise function further led to an engineering model for mass loss, neglecting the effects of blunting, which successfully related the work done by friction to the mass loss due to surface melting of the nose. In this paper, a generalized dimensionless nose equation is developed, allowing these results to be applied to geometries other than the ogival case. Furthermore, the effects of blunting and progressive mass loss from the nose are incorporated into the existing model of high-speed penetration and applied to the analysis of previously reported penetration data. By incorporating changing nose mass and geometry due to frictional wear, the performance characteristics of steel alloys and selected nose geometries can be better evaluated, and the processes governing high-speed penetration and mass loss better understood. Given penetrator material, impact velocity and target properties, it is also possible to predict the performance of various nose geometries.
Endoscopic dacrocystorhinostomy: long-term results and evolution of surgical technique
Authors: Durvasula V.S.P. , Gatland D.J. 
Published: September 2004

This study evaluated the long-term results of endoscopic dacrocystorhinostomy (DCR) performed as a day-case procedure under local anaesthesia. It assessed the patient satisfaction with the procedure by retrospective review and a questionnaire survey.Seventy patients were referred for endoscopic DCR to the senior author between 1997 and 2000. A success rate of 92 per cent was achieved at three months and it was possible to perform 85 per cent of cases under local anaesthetic; 91 per cent were discharged on the same day. Long-term follow up by postal survey revealed that the watering eye had improved following surgery in 83 per cent (follow up range = eight to 66 months; mean = 28.6 months). Eighty-eight per cent were satisfied with the tolerability of the procedure under local anaesthesia.The authors describe changes in technique, which evolved with their experience of the procedure. Endoscopic dacrocystorhinostomy can be performed safely and successfully as a day-case procedure under local anaesthesia with excellent results and with great satisfaction to the patients.
Granuloma annulare presenting as multiple nodules on the pinna
Authors: Raghava N. , Mitchard J.R. , Youngs R.P. 
Published: September 2004

Granuloma annulare is a benign, idiopathic, inflammatory dermatosis characterized clinically by dermal papules and annular plaques. We describe the case of a 40-year-old man who presented with a long history of multiple nodules on the left pinna. Histological examination revealed the typical necrobiotic granulomas of granuloma annulare. The condition predominantly affects the extremities of children and young adults; cases involving the pinna are extremely rare.Nodular lesions are common in otolaryngological practice, and this case illustrates the need for careful clinical assessment and appropriate biopsy in diagnosing lesions of the outer ear
Frontal sinus obliteration
Authors: Murphy J. , Jones N.S. 
Published: September 2004

This article highlights the indications for frontal sinus obliteration and suggests some intra-operative points to aid the surgeon in performing the operative procedure. It also reiterates the three principal points that need to be followed. There must be:(1) Meticulous removal of all visible mucosa and the inner bony cortex of the sinus wall.(2) Permanent occlusion of the nasofrontal duct.(3) The correct choice of material for the obliteration.
Ximelagatran: An Oral Direct Thrombin Inhibitor
Authors: Dager William E , Vondracek Thomas G , McIntosh Bruce A , Nutescu Edith A 
Published: September 2004

OBJECTIVE To present the chemistry, pharmacology, and pharmacokinetics of ximelagatran, an oral direct thrombin inhibitor (DTI), and to review available comparative clinical trial data evaluating its efficacy and safety relative to other antithrombotic agents in the prevention and treatment of thromboembolism. DATA SOURCES A search of the PubMed and Cochrane databases (1995–August 2004), supplemented by a manual search of article bibliographies, conference abstracts, and data on file from the manufacturer, was conducted. Key search terms were ximelagatran, melagatran, H376/95, and direct thrombin inhibitors. STUDY SELECTION AND DATA EXTRACTION Pertinent information from available clinical trials, including study design, patient demographics, dosing regimens, anticoagulant comparators, methods for evaluating effectiveness, treatment outcomes, adverse events, and pharmacokinetic and pharmacodynamic evaluations, was extracted. DATA SYNTHESIS Ximelagatran is an orally administered DTI under development for use in the treatment of venous thromboembolism (VTE), long-term prevention of a second VTE event, stroke secondary to atrial fibrillation, prevention of VTE after orthopedic procedures, and recurrent ischemic events after acute myocardial infarction. CONCLUSIONS Ximelagatran, in twice-daily doses of 24 or 36 mg, is an alternative to low-molecular-weight heparins or warfarin in thromboprophylaxis following orthopedic knee replacement, atrial fibrillation, or initial treatment of VTE. Improved outcomes versus placebo were seen in the long-term prevention of VTE in patients who completed an initial 6 months of treatment. Liver-related effects need further clarification.
Clay minerals in the Meuse-Haute Marne underground laboratory (France): Possible influence of organic matter on clay mineral evolution
Authors: Claret Francis , Sakharov Boris A. , Drits Victor A. , Velde Bruce , Meunier Alain , Griffault Lise , Lanson Bruno 
Published: September 2004

AbstractA clay-rich Callovo-Oxfordian sedimentary formation was selected in the eastern Paris Basin (MHM site) to host an underground laboratory dedicated to the assessment of nuclear waste-disposal feasibility in deep geological formations. As described initially, this formation shows a mineralogical transition from an illite-smectite (I–S) mixed-layered mineral (MLM), which is essentially smectitic and randomly interstratified (R = 0) in the top part of the series to a more illitic, ordered (R ⩾ 1) I–S in its deeper part.This description has been challenged by using the multi-specimen method developed by Drits et al. (1997a) and Sakharov et al. (1999). It is shown that all samples contain a physical mixture of an unusually (?) illitic (∼65% I) randomly interstratified I-Exp (illite-expandable MLM) and of a discrete smectite, in addition to discrete illite, kaolinite and chlorite. Structural parameters of the different clay phases vary little throughout the series. According to the proposed model, the mineralogical transition corresponds to the disappearance of smectite with increasing burial depth.Comparison with clay minerals from formations of similar age (Oxfordian-Toarcian) throughout the Paris Basin shows that the clay mineralogy in the deeper part of the series originates from a smectite-to-illite transition resulting from a low-temperature burial diagenesis. The anomalous lack of evolution of clay minerals in the upper part of the series is thought to be related to specific interactions between organic matter and clay minerals.
Smectite-to-illite alteration in salt-bearing bentonites (The East Slovak Basin)
Authors: Honty M. , Uhlík P. , Šucha V. , Čaplovičová M. , Franců J. , Clauer N. , Biroň A. 
Published: September 2004

AbstractThe effect of a saline environment on illitization in volcanoclastic rocks is examined in deep boreholes in the East Slovak Basin. Based on X-ray diffraction analysis, it is concluded that illite-smectite (I–S) expandability is always less in the salt-bearing bentonites (SBB) than in the salt-free bentonites (SFB) for a given depth interval. These two lithologies can be distinguished easily by water-leachate chemistry. Within the depth interval 2100–2500 m, the expandability in SBB varies within the range 25–10% expandable with R1 and R3 ordering in SBB and 68–35% expandable with R0 ordering in SFB. In two shallow SBB samples the expandability is close to that of SFB, suggesting that salinity alone does not enhance the illitization; but salinity may enhance it when combined with higher burial temperature. Vitrinite reflectance and Tmax of RockEval pyrolysis measured in adjacent shales confirm that the increased illitization in SBB is not due to heating and/or erosion. The model of burial and thermal history calibrated by organic maturity suggests that the same thermal history produces two different expandabilities in the two lithologies (SBB and SFB). Particle thickness measurements and K-Ar data were used to deduce the crystal growth mechanism of illitization in SBB. Whereas surface-controlled growth is typical for SFB, simultaneous nucleation and growth played a more important role in the case of SBB. The effect of a salty environment on the illitization is not yet fully understood and may have severe consequences for the utilization of bentonites as engineering barriers in radioactive waste disposal sites if salt formations used as host rocks are taken into account.
Modeled shale and sandstone burial diagenesis based on the K-Ar systematics of illite-type fundamental particles
Authors: Clauer Norbert , Rousset Davy , Środoń Jan 
Published: September 2004

AbstractThe clay fraction of the sedimentary succession beneath the Mahakam Delta (eastern Kalimantan, Indonesia) consists mainly of mixed-layer illite-smectite, with minor amounts of kaolinite and/or dickite, discrete detrital illite and chlorite. On the near-shore anticline, evolution of this mixed-layer material is characterized by a decrease in expandability with depth. The mechanism of conversion of smectite to illite layers depends on the lithology of the host rocks: it evolves along a solid-state transformation in the shales and a dissolution-precipitation in the sandstones.Illite fundamental particles from two sandstones buried at ∼4000 m in the Tambora field next to the Handil field on the same near-shore anticline yield a mean K-Ar age of 15.7±1.6 Ma (2σ), which is younger than the stratigraphic age but still slightly biased by minute amounts of discrete detrital illite. Recalculated after modeling, which takes into account the occurrence of the discrete detrital illite, this K-Ar age becomes 14.4±0.7 Ma. The K-Ar values of the fundamental particles from associated buried shales are significantly older, which can be explained by a mixture of (1) a precursor material similar to that presently deposited in the delta of the Mahakam River, and (2) authigenic fundamental particles incorporating Ar with a 40Ar/36Ar ratio above atmospheric value during nucleation and growth on the same detrital precursor.Application of the modeling to the burial evolution of <0.4 µm particles from both the shales and the sandstones of the basin points to a contribution of detrital micaceous material in both lithologies, (1) in the sandstones as a detrital component dissolving progressively and mixed mechanically with the authigenic fundamental particles, and (2) in the shales as a detrital precursor progressively releasing radiogenic 40Ar by burial alteration, and at the same time acting as a support for the fundamental particles for the growth of authigenic fundamental particles that were found to incorporate Ar characterized by an excess of 40Ar.
Parallel intergrowths in cronstedtite-1T: Implications for structure refinement
Authors: Ďurovič Slavomil , Hybler Jiří , Kogure Toshihiro 
Published: September 2004

AbstractCronstedtite is a member of the kaolin-serpentine group. It yields a wealth of more or less disordered polytypes. The crystals of polytype 1T (space group P31m, a = 5.512, c = 7.106 Å) contain, within coherently scattering blocks, variable concentrations of stacking faults so that domains of the basic 3D periodic structure can be shifted by 1/3 (a2 − a1) or 1/3(a1 − a2). These so-called OD parallel intergrowths have been confirmed by high-resolution transmission electron microscopy. The effect manifests itself in the diffraction pattern so that reflections with h-k = 3n — the family reflections — are always sharp, whereas remaining reflections — the characteristic polytype reflections — may be smeared out parallel to c*. The intensities of the latter are thus underestimated during diffractometer measurements. An analysis of such multiple OD intergrowths reveals that the moduli of structure factors for all characteristic (i.e. non-family) polytype reflections are reduced relative to those calculated for the non-intergrown basic structure, by a common factor. This fact usually leads to the appearance of ghost peaks in Fourier maps and to their erroneous interpretation. The structure of the basic model can, however, be refined much better if two scale factors are assigned to the family and non-family reflections, respectively.
Very low-temperature alteration of sideromelane in hyaloclastites and hyalotuffs from Kilauea and Mauna Kea volcanoes: Implications for the mechanism of palagonite formation
Authors: Drief Ahmed , Schiffman Peter 
Published: September 2004

AbstractThree petrographically distinct styles of altered glasses in two hyaloclastites and one hyalotuff were studied. The texture and chemistry of these samples were investigated using electron probe microanalysis, scanning electron microscopy and transmission electron microscopy in order to understand better the mechanism by which alteration of sideromelane and formation of palagonite occurred in these samples. The results show that clay minerals (primarily smectites) are present in three different microenvironments: (1) coating the surfaces of glass and crystals or vesicle walls; (2) as a relatively heterogeneous, but well crystallized, replacement product (i.e. reddened smectite grain replacement or RSGR) of glass or; (3) as a relatively homogeneous, amorphous to poorly crystalline replacement product (i.e. palagonite). Both the grain size and composition of these smectite-like materials vary considerably.Crystalline smectites occur in both hyaloclastites and have an intermediate composition between the two end-members nontronite and saponite. This composition could correspond to a mechanical intergrowth and/or an interstratification of two different smectites: one dioctahedral (i.e. nontronite) and one trioctahedral (i.e. saponite or stevensite) or simply to a true di-trioctahedral smectite. The coating smectite appears to have precipitated by a paragenetically-early, dissolution-precipitation mechanism prior to the formation of the RSGR. The high Ti content found in RSGR is attributable to an amorphous Ti-rich material which is intergrown with smectite and which behaves as a sink for immobile elements and those not included in smectite.Palagonite from both hyaloclastites and hyalotuff is poorly to non-crystalline and more aluminous than the coating smectites. Palagonite from the hyalotuff has an Fe-rich montmorillonite-like composition. The TEM images show a 30–50 nm thick leached layer formed by selective (non-stoichiometric) dissolution that takes place in the fracture domain. The hydration and replacement of glass during the palgonitization process is accompanied by the loss of Fe, Mg and Ca with a concomitant gain of Al. Both palagonites (from hyaloclastites and hyalotuff) show smilar textural and chemical characteristics.
Interactions of two sulfonylurea herbicides with organoclays
Authors: Carrizosa Maria Jose , del Carmen Hermosin Maria , Koskinen William C. , Cornejo Juan 
Published: September 2004

AbstractThe sorption of two sulfonylurea herbicides (SU), metsulfuron methyl and nicosulfuron, on pure clays and organoclays was investigated. Three clays (Arizona smectite, SAz-1, Wyoming smectite, SWy-2, and hectorite, SHCa-1), were treated with amounts of octadecylammonium (ODA) or dioctadecyldimethylammonium (DODMA) cations equal to ∼50 and 100% of the clays’ cation exchange capacity (CEC). Sorption isotherms were fitted to the Freundlich equation. While no measurable sorption was found on the pure clays (Kf = 0), organoclays prepared using both primary and quaternary amines were effective as SU sorbents. The metsulfuron methyl Kf values ranged between 196 and 1498 µmol1−1/n kg−1 L1/n, and Kf values for nicosulfuron, which were lower than those of metsulfuron methyl, ranged from 35 to 198 umol1−1/n kg−1 L1/n. As shown by sorption coefficients, Kd and KOC, SWy-2 treated with DODMA at ∼100% of the CEC was the most effective sorbent for metsulfuron, Kd = 684 L kg−1 and KOC = 2138 L kg−1. For nicosulfuron the most effective sorbent was SAz-1 with ODA at ∼ 50% of the CEC (Kd = 147 L kg−1 and KOC = 1233 L kg−1). In contrast to other weak-acid herbicides, such as phenoxy and picolinic acids, no clear relationships were found between sorption and layer charge, organic carbon content, and basal spacing of the organoclays for both sulfonylurea herbicides. Sorption of both herbicides on organoclays was assumed to involve hydrophobic and polar interactions for which the availability of interlayer room between organocations was a very important factor.
Chronic Haloperidol Promotes Corticostriatal Long-Term Potentiation by Targeting Dopamine D2L Receptors
Authors: Centonze Diego , Usiello Alessandro , Costa Cinzia , Picconi Barbara , Erbs Eric , Bernardi Giorgio , Borrelli Emiliana , Calabresi Paolo 
Published: September 2004

Reduced glutamate-mediated synaptic transmission has been implicated in the pathophysiology of schizophrenia. Because antipsychotic agents might exert their beneficial effects against schizophrenic symptoms by strengthening excitatory transmission in critical dopaminoceptive brain areas, in the present study we have studied the effects of acute and chronic haloperidol treatment on striatal synaptic plasticity. Repetitive stimulation of corticostriatal terminals in slices induced either long-term depression or long-term potentiation (LTP) of excitatory transmission in control rats, whereas it invariably induced NMDA receptor-dependent LTP in animals treated chronically with haloperidol. Haloperidol effects were mimicked and occluded in mice lacking both D2L and D2S isoforms of dopamine D2 receptors (D2R-/-), in mice lacking D2L receptors and expressing normal levels of D2S receptors (D2R-/-;D2L-/-), and in mice lacking D2L receptors and overexpressing D2S receptors (D2L-/-). These data indicate that the blockade of D2L receptors was responsible for the LTP-favoring action of haloperidol in the striatum. In contrast, overexpression of D2S receptors uncovered a facilitatory role of this receptor isoform in LTP formation because LTP recorded from D2L-/- mice, but not those recorded from wild-type, D2R-/-, and D2R-/-;D2L-/- mice, was insensitive to the pharmacological blockade of D1 receptors.The identification of the cellular, molecular, and receptor mechanisms involved in the action of haloperidol in the brain is essential to understand how antipsychotic agents exert their beneficial and side effects.
Spectroscopy: Applications
Authors: Serrano‐Andrés Luis , Merchán Manuela 
Published: September 2004

AbstractRecent years have seen an extraordinary development in the applicability and accuracy ofab initiomethods to compute molecular excited states, which are now generally determined with a precision of 0.1–0.2 eV. The size and character of the problems have increased to make the calculations competitive and complementary to the experimental determinations involving medium and large molecular systems. Many examples can be provided of this new era in the quantum chemistry of the excited state where the multiconfigurational methods, in particular, CASPT2, have been the main protagonists. The present article contains an account of the types and nature of excited states, a compilation of methods, strategies, and problems to be solved in the calculation of molecular excited states, particularly to obtain electronic transition energies and properties, such as band intensities and state lifetimes. Finally, a number of examples and achievements in the field give an overall view of what can be computed nowadays and how the computations can be performed. Illustrative examples include the calculation of dark states, vibrational resolution of electronic bands, novel assignments, interplay between theoretical spectroscopy and experiment, and adiabatic and nonadiabatic photochemical processes.
The Use of N‐Alkyl‐2,2′‐bipyrrolidine Derivatives as Organocatalysts for the Asymmetric Michael Addition of Ketones and Aldehydes to Nitroolefins
Authors: Andrey Olivier , Alexakis Alexandre , Tomassini Axel , Bernardinelli Gerald 
Published: September 2004

AbstractThe direct Michael addition of aldehydes and ketones to nitroolefins, catalyzed by N‐i‐Pr‐2,2′‐bipyrrolidine, is described. The desired 1,4‐adducts are obtained in excellent yields with enantioselectivities up to 95% ee and dr up to 95 : 5 of the syn aldehyde addition product. An unexpected inversion of diastereoselectivity was observed for the addition of α‐hydroxy ketones to β‐arylnitroolefins with enantioselectivities up to 98% ee. The formation of an internal hydrogen bond between the OH group of the α‐hydroxy ketone and the tertiary nitrogen of the catalyst leads to the formation of a rigid cis enamine intermediate that accounts for the inversion of the expected diastereoselectivity and the very high ees.
A New Approach to Axially Chiral Bipyridine N,N′‐Dioxides Bearing Aromatic Substituents and their Use for Catalytic Asymmetric Allylation of Aldehydes with Allyl(trichloro)silane
Authors: Kina Asato , Shimada Toyoshi , Hayashi Tamio 
Published: September 2004

AbstractPalladium‐catalyzed cross‐coupling of bipyridine N,N′‐dioxide 6,6′‐dichloride (Rnap,Rpyr)‐1 with the aryl Grignard reagents opened a new approach to axially chiral bipyridine N,N′‐dioxides (R)‐2 bearing a variety of aryl groups at the 6 and 6′ positions. One of the N,N′‐dioxides (R)‐2d which is substituted with 3,5‐dimethyl‐4‐methoxy groups was found to be highly catalytically active and enantioselective for the asymmetric allylation of aldehydes with allyl(trichloro)silane. The allylation took place with 0.01–0.1 mol % of (R)‐2d giving homoallyl alcohols of up to 94% ee.
Planar Chiral PHANOLs as Double Hydrogen Bonding Donor Organocatalysts: Synthesis and Catalysis
Authors: Braddock D. Christopher , MacGilp Iain D. , Perry Benjamin G. 
Published: September 2004

Abstract4,12‐Dihydroxy[2.2]paracyclophanediol (PHANOL; 1), and its para‐substituted derivatives 2, 5 and 7, were found to catalyse Diels–Alder cycloadditions of α,β‐unsaturated aldehydes or ketones with dienes and/or epoxide ring opening reactions with amines. The mode of catalysis by the PHANOLs is via double hydrogen bonding to the two sp2 lone pairs of a carbonyl group or the two lone pairs of the epoxide. The order of activity of the PHANOLs for catalysis of the Diels–Alder reaction essentially correlates with the expected hydrogen‐bond donor strength based on the degree of electron‐withdrawing capability of the group(s) in the para position. In contrast, ortho‐substituted PHANOLs 10, 11 and 14 were not active as catalysts due to steric interference with the double hydrogen bonding mode. 1H NMR and IR spectral data for the various PHANOLs are discussed in support of the proposed double hydrogen bond mode.