bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Modal Auxiliaries of Volition in Classical Chinese
Authors: Peyraube Alain 
Published: November 2023

Abstract
The history of the modal auxiliaries, aptly called wish verbs in Mandarin Chinese (nengyuan dongci fl llni/Jil!]), is extremely complex, and any brief discussion of the subject, as given in several books on Chinese historical syntax (Ohta 1958; Shi Cunzhi 1986; Sun Xbcin 1992) inevitably involves gross oversimplification. It is all the more difficult to determine the main lines of their evolution since the use of the modal auxiliaries of Standard Classical Chinese (Late Archaic Chinese of the pre-Qin period, fifth to third centuries BCE) is itself far from clear.
Experimental Study of Heavy-Gas Dispersion on Sloping Surf aces
Authors: Müller J , Fanneløp T K 
Published: November 2023

Abstract
The motion of a dense-gas cloud is known to be strongly influenced by slopes. Various theoretical models have been proposed but the scarcity of experimental data makes their validation difficult. An extensive experimental study of heavy-gas clouds suddenly released on uniform sloping surfaces was therefore undertaken. Both, cylindrical releases on an unobstructed surface and 2-d releases in a channel were investigated. The parameters varied include the gas density, the release volume and aspect ratio, and the slope. A new model combining the slumping motion of the cloud, calculated using a modified box-model, with the slope-dependent motion of its center of gravity, is proposed herein. Good agreement with experimental data is obtained in general as well as in the limit of zero slope and in the early spreading phase.
Confined and Unbounded Mixing in Stratified Flows
Authors: Redondo J M , Sanchez M A , Cantalapiedra I R 
Published: November 2023

Abstract
Several laboratory experiments have been used to study the vertical structure and the mixing efficiency across sharp and linear density interfaces. The two laboratory experiments described here exhibit no mean velocity shear; in the first one the turbulence is generated by a horizontally oscillating grid or rod system, in the other experiment a line of air bubbles injected in the base of a stratified tank produces localized mixing. We will consider here mixing in zero mean flows with a constant input of external kinetic energy, as well as the decay of the turbulence.
Breaking Progressive Internal Gravity Waves: Two-Dimensional and PreliminaryThree-Dimensional Numerical Experiments
Authors: Koudella C , Staquet C 
Published: November 2023

Abstract
The dynamics of progressive internal gravity waves of small amplitude are studied by means of two-dimensional (5122) and preliminary threedimensional (643) direct numerical simulations of the Boussinesq equations. Our results show that an internal wave always breaks (for a viscosity low enough), this event being initiated by resonant interactions. A turbulent regime sets in after breaking. This regime is characterized by kinetic and potential energy spectra that behave as aN2k-3, thelevel a for potential energy being identical as that found in the oceanic thermocline (for example Gregg, 1987). The overall dynamics are analogous to that found for a two-dimensional standing internal gravity wave by Bouruet-Aubertot et al. (1995, 1996). This suggests that small scale geophysical flows, which mainly involve progressive internal waves, may be studied by laboratory experiments, where standing waves are mainly encountered.
The Development of Layers in a Stratified Fluid
Authors: Goudsmit G -H , Wüest A 
Published: November 2023

Abstract
The character of perturbations in a stratified fluid varies with the flow stability, as indicated by a Richardson number Ri. At low Ri, turbulent motions lead to diffusion-like mixing, whereas at high Ri, a combination of horizontal, vortical motions and internal waves lead to intermittent mixing dominated by wave-breaking events. Data from some laboratory experiments show that at high Ri, the mixing efficiency decreases with increasing Ri, allowing the possibility that small perturbations away from a smooth density profile may be enhanced to give interfaces. This implies that strongly stratified fluids have a naturally layered character, and may explain the prevalence of fine structure observed in density profiles of the oceans.
The Erosion of a Salinity Step by a Localized Heat Source
Authors: Leppinen D M , Dalziel S B 
Published: November 2023

Abstract
In this paper we compare the erosion of a salinity step by a localized heat source with the erosion of the same salinity step by a distributed heat source. Upper and lower bounds are obtained for the time required for the merger of the two layers and it is shown that a localized heat source is more efficient at eroding a salinity step than a distributed heat source providing the same total heat input. The underlying physical mechanisms controlling the erosion of a salinity step by a localized heat source are identified through the use of laboratory experiments and numerical simulations and these mechanisms are compared with those involved in the erosion of a salinity step by a distributed heat source.
Three-Dimensional Plume of the Rhône River
Authors: Durand Nathalie , Arnoux-Chiavassa Sandrine , Ouillon Sylvain , Rey Vincent , Fraunié Philippe 
Published: November 2023

Abstract
This paper relates to the three-dimensional study of the Rhone river plume hydrodynamics. This work is both experimental and numerical: during a field campaign in the delta area experimental data have been collected and three-dimensional numerical simulations of the dynamical fields and transport of suspended matter have been carried out.
Vertical Dispersion of Passive Scalars Within and Across Stably Stratified Inversion Layers
Authors: Schilling V , Etling D 
Published: November 2023

Abstract
Transport of substances into and across inversion layers has been simulated numerically by means of a two-dimensional finite difference model. Two simulation experiments have been selected in order to demonstrate dispersion of passive scalars caused by Kelvin-Helmholtz instabilities and breaking gravity waves, respectively.
Beamsteering Analysis of Internal Gravity Waves in the Stable Atmospheric Boundary Layer
Authors: Denholm-Price J C W , Rees J M , Anderson** P S , King** J C 
Published: November 2023

Abstract
In this paper we present some preliminary findings from the preparation of a gravity wave climatology at Halley IV station, Antarctica, using data gathered during the second phase of the British Antarctic Survey’s Stable Antarctic Boundary Layer Experiment in 1991 (STABLE II). The method of “beamsteering” is used to evaluate wave parameters from data gathered using an array of six microbarographs. Results are presented from artificial data designed to test the beamsteering code and also to compare it with the “correlation” method used in a previous study. Two case studies which illustrate the kind of wave events observed during the STABLE II programme are described.
Separated Flow Around Bluff Obstacles at Low Froude Number; Vortex Shedding and Estimates of Drag
Authors: Hunt* J C R , Fernando** H J .S 
Published: November 2023

Abstract
For stably stratified flows around bluff obstacles we review different concepts for how sloping vortices are shed from the obstacle surfaces and develop in the regions of separated flow. Approximate analyses are developed for the vortices and the disturbances to the density field that they generate. New experiments were undertaken to study how these shed vortices oscillate, distort and break up; results are broadly consistent with the analysis. Thence a tentative synthesis is proposed for the separated wake structure downstream of bluff obstacles and of mountains in stable flows. This explains the observations that the separated regions have a minimum thickness at one particular Froude number which, it is suggested, also implies a minimum in the drag.
Nitrogen, oxygen and sulfur ylides: an overview
Authors: Clark J Stephen 
Published: November 2023

Abstract
Over the past three decades, there has been a rapid increase in the use of oxygen, nitrogen and sulfur ylides in organic synthesis. This is due in large part to the discovery of mild, efficient and general methods for the generation of these unstable and highly reactive intermediates. Much of the impetus for the exploitation of oxygen, nitrogen and sulfur ylides in organic synthesis has resulted from the discovery that these intermediates have a rich chemistry that can be used for the rapid preparation of highly functionalized compounds from relatively simple components. The development of mild catalytic methods for the preparation of a wide range of oxygen, nitrogen and sulfur ylides has generated further interest in these intermediates.
Reactions of hydroxyl groups
Authors: David Serge 
Published: November 2023

Abstract
In the majority of sugars, all carbons are functional. When a particular function is to be modified using traditional organic chemistry methods, the other functions need to be ‘protected’. This means they are first transformed into derivatives that are inert under the desired reaction conditions, then reconverted into the starting function during a subsequent step. This last phase is called the ‘deprotection’ step. It is often useful to protect diverse functions of the same molecule by derivatizations of a different nature in order to effect selective deprotections. We have already encountered the most general type of protection of the hemiacetal hydroxyl group, that is the glycosidation reaction (see Chapter 3). In this chapter we will not talk only about protection reactions. Certain functional derivatives play an analytical role and it is quite useful to know how to synthesize phosphates and sulfates, widely distributed natural products. The sulfonates will be treated in Section 6.1 as an introduction to reactions with inversion of configuration.
Changes of configuration; unsaturated and branched-chain sugars
Authors: David Serge 
Published: November 2023

Abstract
The most frequently used displacement method of a hydroxyl group begins with its conversion to sulfonate. Sulfonates of the secondary hydroxyl groups of sugars are not very reactive with respect to external nucleophiles. This is no doubt a result of the high functionalization of the molecule which combines steric hindrance with an unfavourable inductive effect. Substitution, practically impossible with former techniques, only became a current operation following two innovations. The first was the introduction of polar aprotic solvents; the favourite solvent is N,N-dimethylformamide since this is the easiest to eliminate at the end of the reaction, by extracting it with water from an ether solution.
Sugars in chiral synthesis
Authors: David Serge 
Published: November 2023

Abstract
The experiments we are about to describe bring into play chiral reagents constructed from a titanocene (titanium-carbohydrate complex) (Riediker and Duthaler 1989a; Duthaler et al. 1989; Bold et al. 1989; Riediker et al. 1989b). The starting compound is cyclopentadienyltitanium(IV) trichloride, C5H5TiCl3, which is prepared from dichloride (C5H5)iTiC12 by heating with TiC14. This trichloride reacts with 1,2:5,6-di-0-isopropylidene-α-D-glucofuranose (‘diacetone glucose’) in the presence of triethylamine to provide the bis-titanate 8.1. The latter is a crystalline compound, hence its structure could be determined in the solid state. Its form is that of a three-legged piano stool with the cyclopentadiene ring being its seat. The two ligands have completely different orientations with respect to the cyclopentadienyl ring. Because of this, they create a chiral cavity around the titanium atom. A study of the NMR spectra of 8.1 in solution indicates neither inversion at the metal centre nor rapid ligand exchange. This suggests that the conformation in solution is close to the conformation in the crystal.
Chemical transformations and synthesis of oligosaccharides
Authors: David Serge 
Published: November 2023

Abstract
Reducing oligosaccharides have two different hydroxyl functions, namely the alcohol and the hemiacetal. The alcohol functions are divided into two fairly well differentiated categories, primary and secondary. More subtle differences exist between the secondary alcohol functions, depending on their being axial or equatorial, or combined in a vicinal diol, etc. With respect to monosaccharides, there is nothing fundamentally new here and what is known about the chemistry of oligosaccharides relies on corresponding selective reactions.
The biogeography of grebes
Authors: Fjeldså Jon 
Published: November 2023

Abstract
Grebes have a worldwide (cosmopolitan) distribution (Fig. 5.1), but they are poorly represented in tropical lowlands, and are absent from the high arctic (and Antarctic) regions. The strongholds of grebes are in the temperate steppe biomes and forest/steppe transitions, where the majority of wetlands are shallow depressions, often with mineral-rich and slightly alkaline water, promoting high biological production. Grebes are abundant even in the wetlands of some of the high-altitude steppes in Central Asia and South America, to well above 4 000 m as.
Breeding and life history
Authors: Fjeldså Jon 
Published: November 2023

Abstract
Grebes have become independent of firm land by building floating nest platforms and back-brooding their young. Both behaviours are universal in grebes, suggesting that they were well developed before the differentiation of modern species began. However, grebes which nest solitarily in richly vegetated ponds (notably piedbills, dabchicks, and White-tufted Grebes) often return for 2–3 weeks to brood the young on the nest by night and during bad weather, and sometimes even build extra platforms for brooding and loafing. Thus, some variation is seen in the development of back-brooding.
Environmental threats
Authors: Fjeldså Jon 
Published: November 2023

Abstract
Grebes face some of the same threats as northern diving ducks ( Margin ) and loons, such as toxins, oil-spills, and mortality in fishing-nets—but differ from them because of their dependence on shallow wetlands in the best agricultural districts of the world. Within Europe and USA, more than 50% of the wetland area has been lost over the last 100 years.
The family Podicipedidae
Authors: Fjeldså Jon 
Published: November 2023

Abstract
As a general introduction to the now living grebes, their fossil history and evolutionary relationships are reviewed in this section. This includes a phylogenetic analysis not previously published. The newest formal classification of grebes was that by Stored (1979) in Peter’s Checklist of Birds of the World. The majority of fossil grebes are, with the exception of the early forms mentioned on p. 25, discussed in connection with now living genera or species.
GCD sums with applications
Authors: Harman Glyn 
Published: November 2023

Abstract
Asymptotic formulae reduced to GCD sums. Bounds for GCD sums. Extensions to higher dimensions. Applications to the Duffin-Schaeffer problem. A generalization of Khintchine’s theorem. Sums involving common divisors were introduced in one context in the previous chapter. The following result demonstrates how they arise in a related problem.
Radical-Mediated Protein Oxidation
Authors: Davies Michael J , Dean Roger T 
Published: November 2023

Abstract
Protein oxidation by free radicals is thought to play a major role in many oxidative processes within cells, and is implicated in human disease, carcinogenesis, and ageing. This unique and comprehensive volume brings together up-to-date information on the oxidation of amino acids, peptides, and proteins by free radicals and discusses the roles of such processes in biological systems. Topics include: the chemistry of amino acid and protein oxidation; the biochemical consequences of these reactions; the role of protein oxidation in normal physiology; the potential importance of protein oxidation in human health - including ageing, heart disease, cancer, inflammation and neurodegenerative diseases - and the possible prevention of such processes by antioxidants and other protective strategies.
A historical survey of the study of radical-mediated protein oxidation
Authors: Davies Michael J , Dean Roger T 
Published: November 2023

Abstract
We will give here particular emphasis to the studies before 1970, since those published subsequently are more immediately pertinent to the discussions of later chapters, and are also reasonably well represented in the major review articles we have already listed in the Preface. The first publication we have located on radical-mediated amino acid oxidation without the addition of acid is that of Dakin (1906), and it is also the earliest of those referenced in the major reviews of Garrison (1968) and Stadtman (1993). It is worth summarizing the perceptive work it embodies, both as a taste of the openings of a field, and because of its entertaining contrasts with the styles of experiment and presentation we follow today. The paper is in the first volume of the Journal of Biological Chemistry (JBC) now by far the most extensive journal of biochemistry, publishing around 30 000 pages per volume, but then a modest, small-format single volume for the years 1905–6. It is also amusing and impressive to note that Dakin’s follow-up publication 2 years later (Dakin 1908a) was accompanied by a large batch of other single-author publications of his own, taking up roughly half of the volume of JBC! Such relative occupancy would be impossible even for a large group to achieve today.
The pathology of protein oxidation
Authors: Davies Michael J , Dean Roger T 
Published: November 2023

Abstract
We will devote most of this chapter to focusing on a limited number of pathologies in which it has been possible to make some analysis of the importance of protein oxidation. However, we first wish to summarize the occurrence of products of protein oxidation in a range of pathological situations (Table 5.1), to complement the discussion of Chaper 4. Many, but not all, pathologies are accompanied by the presence of oxidized proteins at levels beyond the physiological. The difficulty, as always, is in distinguishing ‘bystander’ oxidation, which is a quite secondary consequence of the pathology, from that which might be important in its progression.
Scandium(III) and yttrium(III)
Authors: Fukuzawa Shin-Ichi 
Published: November 2023

Abstract
According to the inorganic chemistry text book written by Cotton and Wilkinson, scandium is not truly a rare earth element but yttrium and lanthanides are rare earth elements. The stable oxidation state of scandium is trivalent and the ionic radius of scandium (III) is significantly smaller (0.89 Å) than those for any of the rare earth elements (1.0-1.17 Å). Chemical behaviour is intermediate between aluminium and that of lanthanides. Yttrium has a trivalent oxidation state similar to scandium and lanthanide elements and the ionic radius of yttrium (III) (1.04 Å) is close to those of erbium (1.03 A) and holmium (1.04
Zinc-mediated Barbier reactions
Authors: lucre Jean-louis , Sarandeses luis A 
Published: November 2023

Abstract
Among the synthetic accesses to alcohols, the nucleophilic addition of organometallics to carbonyl groups is certainly one of the more versatile and frequently used, and can be achieved by using a Grignard reaction. The paramount importance of the latter has left somewhat in the shade the Barbier reaction, frequently considered as its ‘ancestor’ in all respects. Barbier’s student V. Grignard discovered the two-step procedure to which his name remained attached, as a development of the original one-step condensation between an organic halide, a carbonyl compound, and a metal (Scheme 15.1).1•2 The latter, direct and easy to perform, has a number of advantages.
Countercurrent extraction and supercritical fluid fractionation
Authors: Clifford Tony 
Published: November 2023

Abstract
For extraction from a liquid phase, countercurrent supercritical fluid extraction or supercritical fluid fractionation can be carried out. The liquid phase may be a liquid mixture, or a solution containing solutes which are solid at the extraction temperature, or a slurry of solid particles, such as microbial cells. The advantages of these processes are firstly that they are continuous and secondly that they are more efficient than a batch process, if well designed. Batch extraction is a single operation; countercurrent extraction and fractionation are processes in which there a number of stages or plates; and chromatography, described in the next chapter, has a large number of plates. Thus, in a sense countercurrent extraction and fractionation are intermediate between extraction and chromatography. The separation efficiency and costs of these processes increase in the order of extraction, countercurrent extraction/fractionation, and chromatography. It often makes economic sense to perform countercurrent extraction or fractionation as a preliminary stage to concentrate the compound of interest, before carrying out chromatography to obtain a very pure product.
Reactions of selenium nucleophiles
Authors: Engman Lars , Gupta Vijay 
Published: November 2023

Abstract
Because selenolate ions are highly reactive, soft nucleophiles, they can be used for the introduction of selenium into a variety of organic molecules. The preparative usefulness of these organoselenium compounds often relies on one of several constructive ways to manipulate the resulting carbon-selenium bond. For example. these can include selenoxide eliminations (see Chapter 2). lithium-selenium exchange to form carbanions (see Chapter 7) or homolytic cleavage to generate carbon-centred radicals (see Chapter 9). Nucleophilic selenium compounds are also useful for a number of functional group manipulations. In these stoichiometric or catalytic processes. the nucleophilic organoselenium species are used as reagents for the one-step transformation of selenium-free starting materials into selenium-free products (see Chapter 6).
Oxidations with selenium reagents
Authors: Back Thomas G 
Published: November 2023

Abstract
Selenium dioxide is an oxidizing agent that was one of the earliest selenium reagents to find widespread application in organic synthesis, with early examples dating from the 1930s. Its properties, preparation and synthetic applications have been the subjects of both early1 and more recent2 reviews. Several methods exist for its preparation by the oxidation of elemental selenium, and it is also commercially available. Pure selenium dioxide is a white, crystalline solid, but the reagent sometimes has a pink coloration, probably because of the presence of elemental selenium. It can be purified by sublimation. It has limited solubility in most organic solvents and must generally be used in aqueous or alcohol media. In many applications, the active oxidant is probably selenious acid (H2SeO3), the hydrolysed form of the dioxide. Selenium dioxide is toxic and so must be handled with appropriate care. Although the compound itself is not malodorous, by-products formed during oxidations of organic substrates are often volatile and highly unpleasant.
Selenium extrusion reactions
Authors: Jr Frank S Guziec , Guziec lynn James 
Published: November 2023

Abstract
Extrusion reactions of organoselenium compounds have only recently been recognized as particularly useful synthetic methods for the preparation of extremely strained organic molecules. In many cases the corresponding sulfur-based reactions were originally investigated, but for the most part the use of selenium-containing molecules as substrates led to increased reactivity and therefore greater overall synthetic utility. Extrusion reactions may be defined as chemical transformations in which an atom or molecular fragment Y directly attached to two atoms X and Z is excised from a molecule leading to a product in which X is directly bonded to Z (Equation 10.1).2 Usually the substrate is a heterocycle which can be thermally or photochemically induced to extrude a stable inorganic species (e.g. N2, CO2, S, Se).