bluuebunny/crossref_metadata_2025 huggingface dataset:
Anatomy of Thaliacea
Authors: Godeaux J , Bone Q , Braconnot J -C
Published: November 2023

The three thaliacean groups, pyrosomas, salps and doliolids, differ from each other not only in their anatomy, but also in their locomotion, buoyancy, sensory systems and embryonic development. They share, however, metagenetic life-cycles involving alternation of generations (although one generation is only transient in pyrosomas) and essentially similar stolonic budding. Traditionally grouped together, a grouping retained here for convenience, it now seems probable that the Thaliacea are polyphyletic, and thus that their grouping together is artificial (Chapter 16).Pyrosomas are colonial animals, primarily warmwater forms, rather common in tropical and warm temperate waters except in the Red Sea. They are mainly caught in the epipelagic and upper mesopelagic layers, although specimens have occasionally been observed at greater depths (Tregouboff, 1956). In contrast to the other pelagic Tunicates, pyrosomas consist of permanent tubular hollow colonies; the blastozooids resulting from asexual propagation are essentially independent but remain embedded side by side in a common tunic or test, as in the aplousobranchiate Ascidians. These blastozooids are hermaphrodite and blastogenic and are responsible for the propagation of the species and the growth of the colony, whilst the oozooid is only a shortlived transient and blastogenic stage.
Sexual Selection and the Barn Swallow
Authors: Møller Anders Pape , Gregersen Jens
Published: November 2023

An important empirical test of the theoretical predictions of sexual selection theory, this book presents a long-term field study of the monagamous barn swallow. By using information on behaviour, ecology, morphology, genetics, and evolution, the book reviews this theory and its two components: male-male competition and female choice. The selective advantages of a long tail are investigated for this common bird, demonstrating such effects as mating behaviour, copulation behaviour, migration strategies, and host-parasite interactions. A rich informative text which clearly elucidates the mechanisms and consequences of sexual selection.
Sperm competition and sexual selection
Authors: Møller Anders Pape , Gregersen Jens
Published: November 2023

Contrary to the majority of other organisms, most bird species are socially monogamous. Males and females establish a pair bond, and individuals of both sexes contribute to the rearing of offspring. Monogamy may superficially mean mate fidelity. Charles Darwin (1859, 1871) wrongly assumed in his writings that monogamous females were faithful to their mates and therefore only copulated with their own mates. It is well known among farmers and poultry breeders that female domestic chickens and ewes regularly copulate with more than a single male, and this common knowledge must also have been available to Darwin through his extensive correspondence. The point of view that monogamous females copulate only with a single male may have been a consequence of the predominant Victorian moral attitudes of the 19th century. Recent research demonstrates that female copulations with multiple males are ubiquitous in animals (and plants), and that strictly monogamous relationships with complete mate fidelity are rare.
The timing of reproduction
Authors: Lank David B
Published: November 2023

Ornithologists have long accepted that the seasonality of breeding by birds is driven in large measure by the timing of availability of food for young. The extraordinary breeding biology of Emperor Penguins Aptenodytes forsteri, which involves a 3 − 4 month incubation fast by males through the Antarctic winter, testifies to the extreme adaptations which have evolved to ensure that eggs hatch at a time when chicks may be provisioned (Le Maho 1977). Lack (1968) suggested that laying dates, clutch sizes, and chick growth rates were coadapted packages that ensure maximal fitness. Snow Geese start to nest as soon as snow melts on the breeding grounds, and by the end of incubation, suitable food is usually available to support gosling growth. In this chapter, we examine variation in laying date within the normal nest initiation period.
Proboscidean relationships based on immunological data
Authors: Lowenstein Jerold M , Shoshani Jeheskel
Published: November 2023

Morphological reconstructions of proboscidean evolution are now being supplemented by the immunological analysis of fossil elephant proteins. Microcomplement fixation, immunodiffusion. and radioimmunoassay (RIA) methods have been applied to examine the genetic relationships of the extinct woolly mammoth (Mammuthus primigenius, hereafter. M. primigenius), the American mastodon (Mammut americanum). and the living elephants, African (Loxodonta africana) and Asian (Elephas maximus). Here we review the principal finding emanating from the new field of palaeo-immunology, particularly from the very quantitative and sensitive RIA technique. In addition, we discuss new applications of RIA to identify fossils of unknown or uncertain provenance and to confirm the hybrid status of the only known Elephas- Loxodonta hybrid.
Pleistocene dwarf elephants of the California Islands
Authors: Roth V Louise
Published: November 2023

Mammoths of the Santa Barbara, California, Channel Islands are the only proboscideans documented from islands in the New World. Like proboscidean fossils from islands elsewhere, they tend to be dwarfed by comparison with their mainland ancestors, typically attaining as adults 120–180 cm in shoulder height, with a few extreme individuals broadening the range to 105–243 cm (Roth 1982), when their closest relatives on the mainland could reach 400 cm (Orr 1968). (See also Oldale et al. 1987, and Whitmore et al. 1967, on relatively small mammoths from the North Atlantic Continental Shelf.)
South American proboscideans: general introduction and reflections on Pleistocene extinctions
Authors: Casamiquela Rodolfo M , Shoshani, Jeheskel , Dillehay Thomas D
Published: November 2023

Based on available palaeontological, archaeological, and strati¬ graphic evidence, the proboscideans of South America (Cuvieronius, Haplomastodon, Notiomastodon, and Stegomastodon) were either descendants of gomphothere stock originating in North America or had evolved autochthonously, a scenario summarized in Fig. 29.1 of Dudley (this volume, Chapter 29). Immigrants to South America probably arrived via the Pana manian filter during the Pliocene or Plio-Pleistocene boundary. Those, in turn, may have been intermittently isolated and evolved on an ‘island continent’. Little systematic research on South American proboscideans has been carried out. Osborn’s (1936, 1942) information on South American gomphotheres was augmented by Hoffstetter’s (1950, 1952, 1955), and additional observations were made by Simpson and Paula-Couto (1957), especially on the material from Brazil and other countries in South America. None of the more recent publications (e.g. Patterson and Pascual 1972; Webb 1978, 1991; Simpson 1980; Marshall and Cifelli 1990; Marshall et al. 1984) have expanded on these works but have only examined it from different perspectives.
Ecology and breeding biology
Authors: Pratt H Douglas , Jeffrey Jack , Conant Sheila
Published: November 2023

The interactions of Hawaiian honeycreepers and their environment are a pervasive underlying theme in all discussions from evolution to distribution and status. The Hawaiian environment in general was discussed in detail in Chapter 2. Ecological observations appear throughout the discussion of evolutionary phenomena (Chapter 4), and are intimately intertwined with anatomical and functional analyses and natural selection of coloration (Chapter 6), and even to some extent in behaviours such as locomotion and self-maintenance (Chapter 7).
The uniform system
Authors: Matthews John D
Published: November 2023

The term uniform system is an abbreviation of ‘shelterwood uniform system’. It implies a uniform opening of the canopy for regeneration purposes, as well as an even-aged and regular condition of the young crop produced (Robertson 1971). Another name is ‘shelterwood compartment system’, denoting that the canopy is opened out for regeneration over whole compartments at a time. In North America the term ‘seed tree method’ is used for a form of the uniform system in which seed trees are widely spaced over the whole area (Smith 1986).
The coppice system
Authors: Matthews John D
Published: November 2023

This chapter deals with the system known as ‘simple coppice’-a term sometimes used to distinguish it from coppice with standards-together with certain modifications of it, including pollarding. The coppice system involves reproduction by stool shoots or suckers. When felled near ground level most broad-leaved species, up to a certain age, reproduce from shoots sent up from the stump or stool. These shoots, known as stool shoots or coppice shoots, arise either from dormant buds situated on the side of the stool at or near ground level or from adventitious buds arising from the cambial layer round the periphery of the cut surface. The former are more firm on the stool, and are therefore more important for purposes of regeneration. As a rule many shoots arise from each stool but each year some of the smaller shoots die until from 2 to 15 remain, with the result that coppice has a characteristic clumped appearance.
The brown trout and quantitative ecology
Authors: Elliott J M
Published: November 2023

Most readers must have seen a brown trout, if only as one about to be cooked or eaten. They should have noted several features that facilitate manoeuvrability and sustained swimming (Fig. 1.1): a streamlined body covered with overlapping scales; single dorsal and anal fins to prevent rolling and yawing; paired pectoral and pelvic fins to prevent rolling and pitching and to act as brakes; and a well-developed, symmetrical tail that provides the thrust for swimming. Like other members of the salmon family, the trout has a small, fleshy fin posterior to the dorsal fin.
Case-study: population dynamics of migratory brown trout in Black Brows Beck,1966-90
Authors: Elliott J M
Published: November 2023

Some readers may be curious to know how and why someone starts a long-term study that has now lasted over 25 years. This chapter therefore begins with the background to the work; its history and why such long-term field studies are necessary. Next follows a brief description of Black Brows Beck and a more detailed description of the life cycle of the brown trout population. Emphasis is placed on the age structure of the spawning population and the methods used to obtain the population estimates for subsequent analyses. As density-dependent processes figure largely in these analyses, they are discussed in detail. Emphasis is placed on the choice and fitting of a suitable density-dependent model which is usually called a stock-recruitment model when applied to fish populations. Such a model is then used with other methods to determine the chief factors affecting population density and survival for different life stages and different year-classes. Emphasis is placed on the key-factors for population regulation and the relative importance of density-dependent and density-independent factors. Finally, the relevance of the work is discussed.
Ecological differences between brown trout populations
Authors: Elliott J M
Published: November 2023

In the second chapter, taxonomic problems were reviewed for both the family Salmonidae and brown trout (Section 2.2). Although about 50 species have been described in the past, the current view is that all belong to one polytypic species, Salmo  trutta. There is, however, extensive variability within this species with sympatric, reproductively isolated populations. Genetic differences between populations are discussed in more detail in the next chapter. As the brown trout is a highly polytypic species, it is not unexpected that there are often ecological differences between populations. The large variation in life cycles was summarized in the first chapter (Section 2.4.2). Although the life cycle always starts with the eggs being laid in fresh water and the juveniles spending the first year in their natal stream, there are at least four variations for the subsequent life-stages. Older trout either remain in their natal stream for the whole life cycle or migrate to the parent river, a neighbouring lake, or the sea with the adults not returning to their natal stream until just before spawning.
General conclusions
Authors: Elliott J M
Published: November 2023

The chief objectives of this book are to review and synthesize quantitative aspects of brown trout ecology, to identify major gaps in knowledge, and to draw general conclusions whenever possible. This final chapter is rather different from the rest in that it highlights the main conclusions that can be drawn from the preceding chapters, emphasizes their relevance to the conservation and management of brown trout and other salmonids, and speculates on their more general implications for animal ecology. It is perhaps inevitable that some of my personal views and prejudices will surface in this chapter and I hope they will not annoy too many readers. Although many conclusions can be drawn from all the literature covered in the last eight chapters, the following seven are considered to be the most important.
The occurrence of burrow-nesting among birds and its influence on soil fertility and stability
Authors: Furness R W
Published: November 2023

A review of the literature on nesting habits of birds shows that burrow-nesting is regular among only a few species, mostly among Procellariidae, Hydrobatidae, Pelecanoididae and Alcidae, which are all seabirds. With the exception of puffins, most burrow-nesting seabird species visit their colonies only at night. Nesting densities attained by burrowing seabirds can be very high (up to three burrows per square metre). Anecdotal records describe habitat destruction through soil erosion due to burrowing by puffins and shearwaters. However, I present some evidence to suggest that shearwater activity can stabilize slopes.
Calcutta Botanic Garden After Roxburgh
Authors: Desmond Ray
Published: November 2023

Francis Buchanan’s temporary successor at the Botanic Garden, Nathaniel Wallich (né Nathanael Wulff) (1786-1854), was born in Copenhagen, the son of a Jewish merchant. He had been a pupil of Professor Martin Yahl, the author of Symbolae botanicae (1790-4), at the University of Copenhagen, and, on qualifying as a surgeon in 1806, left for the Danish settlement at Serampore on the River Hooghly opposite Barrackpore with an additional commission to collect plants and seeds for the Botanical Garden in Copenhagen. When he took up his appointment as the settlement’s surgeon in 1807, the British fleet had bombarded Copenhagen and following the Company’s annexation of Serampore in 1808, Wallich and his fellow countrymen became prisoners of war. He was released from captivity in June 1809 at the behest of William Roxburgh with the authorization of the Bengal Government to employ him in the Botanic Garden. Roxburgh proposed sending him to the eastern frontier of the Company’s territory to collect plants, an assignment that appealed to Wallich who had professed that knowledge rather than wealth was to be his motivation in life. It comes as a surprise, therefore, that he should soon relinquish this potentially attractive mission to return to Serampore. It would appear he declined the opportunity to be a field botanist because he considered his travelling allowance to be inadequate.
William Griffith and Robert Wight
Authors: Desmond Ray
Published: November 2023

India’s botanical gardens were the designated repositories for plants collected in the subcontinent and neighbouring countries or donated from more distant regions: living plants to be coaxed into flower in the garden and dried specimens to be systematically stored in the herbarium.
The Himalayas
Authors: Desmond Ray
Published: November 2023

While apathy or, at best, subdued activity prevailed in botanical circles in western India, the Himalayas beckoned the adventurous and the curious, among them surveyors and scientists who observed in a casual note or expansive report the indigenous plant and animal life of this complex mountain range which separates India from Central Asia, extending from Afghanistan for 1700 miles to Assam in the East, and continues into China. A diversity of soils and climates, especially the summer monsoons, support what the plant collector, Frank Kingdon Ward succinctly described as an ‘immense reservoir of hardy plants’. A fertile jungle strip, ten to twenty miles wide-the terai-which skirts its eastern ranges is home to slender evergreens such as the sal (Shorea robusta) and tall bamboos. The abundant sal yields to conifers and oaks in a gradual ascent of four or five vertical miles through a progression of rain forest, temperate vegetation, conifers, and rhododendrons to the alpine zone above the tree-line at about 10 000 feet. Everywhere plants have adapted to their environment, a delicate ecological balance which man’s intervention through cultivation, grazing and logging is swiftly destroying with consequent erosion and lowland flooding. The phytogeographical variations range between the arid zones of the Hindu Kush and the warmer, wetter regions of the east, with Kashmir, Nepal, and Sikkim offering bumper harvests for botanist and plant collector.
The pathology of cervical intra-epithelial neoplasia, carcinoma and human papillomavirus infection
Authors: Buckley C Hilary
Published: November 2023

The uterine cervix is one of the tissues forming the lower female genital tract, a term which also encompasses the vagina and vulva. Whilst this text is concerned with the cervix uteri, it must be remembered that human papillomavirus (HPV) infection, intra-epithelial neoplasia, and carcinoma may affect all these tissues simultaneously or asynchronously. Disease in the cervix, therefore, often forms part of a field change in the lower genital tract, and this may influence the course of the patient’s disease and modify their clinical management.
Molecular genetics of human papillomaviruses
Authors: Arrand John R
Published: November 2023

It is an interesting outcome of the age of molecular biology that one can contemplate describing the genetics of an organism when the actual beast itself has not been encountered in a free-living, natural state. Yet this is exactly the situation which pertains to several types of human papilloma viruses. It is only very recently that some of the most widely studied papilloma ‘viruses’ have actually been observed as fully formed particles but even so only in vitro (Sterling et al. 1990). Nevertheless, by virtue of genetic manipulation technology a great deal is known about this fascinating and clinically important genus of the family Papovaviridae.
Introduction
Authors: Ferner R E , Norman Elizabeth , Rawlins M D
Published: November 2023

Serious crime has become a common-place, and drugs have been used in the commission of rape, manslaughter, and murder. Crime related to alcohol, the most important of drugs in a criminal context, has increased remorselessly as the per capita consumption of alcohol has increased.
Ethanol
Authors: Ferner R E , Norman Elizabeth , Rawlins M D
Published: November 2023

Alcohols are alkyl organic compounds which contain an —OH group. Ethanol (ethyl alcohol), C2H5OH, is the chemical name for the alcohol derived from the fermentation of glucose (grape-sugar) and other sugars and starches by the action of yeasts. Since this is economically and socially the most important alcohol, the term ‘alcohol’ often designates ethanol.
The antipsychotic drugs: phenothiazines, butyrophenones, and other agents
Authors: Ferner R E , Norman Elizabeth , Rawlins M D
Published: November 2023

Psychological illnesses can be divided into neurotic and psychotic illnesses. Neurotic illnesses, such as anxiety and depression, are exaggerations of the normal emotions, but (generally) leave the thought processes intact. Psychotic illnesses are marked by a break from normal thought processes. The abnormal thoughts can take the form of hallucinations or delusions, for example. A patient who is miserable because he has no power to influence the wrongs of the world is neurotic; a patient who believes that the Martians are trying to destroy him, or that he himself is a Martian, is psychotic1.
Vaccines
Authors: Ferner R E , Norman Elizabeth , Rawlins M D
Published: November 2023

Vaccines (from Vaccinia, cowpox) were introduced in the eighteenth century by Edward Jenner who discovered that inoculation of a previously unaffected subject with cowpox, a mild skin affection, could protect from subsequent infection with smallpox, a potentially lethal viral disease. It is now recognized as a form of active immunization: the immune system is primed to respond effectively to subsequent infections with the same or similar immunological properties.
Anabolic androgens (anabolic steroids)
Authors: Ferner R E , Norman Elizabeth , Rawlins M D
Published: November 2023

The paradigm anabolic androgen is the naturally occurring sex hormone testosterone, which exerts its actions through specific cellular receptors in the cytoplasm (intracellular fluid) of target cells (Lukas 1993). Testosterone is responsible for the development of male sexual characteristics in utero and for the changes that occur in male maturation: it is androgenic.
The design and generation of probes for in situ hybridization
Authors: Sunday Mary E
Published: November 2023

The design and generation of probes for in situ hybridization (ISH) are critical determinants for the successful outcome of every experiment. It is necessary to use a labelled hybridization probe to detect the mRNA of interest in the target tissue section. There is no concern that nuclear DNA might also hybridize, because the double-stranded DNA is not denatured and thus not available for hybridization in mRNA ISH protocols. A variety of probes can be used, and they can be synthesized in different ways. Most often, radiolabelled probes are used together with autoradiography, but new methods of detecting non-isotopic probes are becoming widely used (see section on probe labelling below).
Supersensitive in situ DNA and RNA localization
Authors: Hacker Gerhard W , Zehbe Ingeborg , Tubbs Raymond
Published: November 2023

In situ detection of specific nucleic acid sequences is possible with a variety of in situ hybridization (ISH) methods, most of which are discussed in this book. Non-isotopic probes possess great advantages over radioactivity labelled probes; not only does the use of non-isotopic reporter molecules, such as biotin, digoxigenin, or fluorescent labels, make it possible to avoid hazardous radiation and to shorten the turnover period, but they also give an improved resolution and are more economic than radioisotopes.
Sibthorp: The Early Years
Authors: Walter Lack H , Mabberley David J
Published: November 2023

In the eighteenth century the landed gentry of Lincolnshire produced two illustrious sons who became famous as explorers: Joseph Banks and John Sibtborp. The first accompanied Captain James Cook on his first voyage round the world, and was elected a Fellow of the Royal Society, knighted, and later sworn in as a member of the Privy Council. As President of the Royal Society for forty years, he had a decisive influence on the development of science in general and the natural sciences in particular. He became known as the father of Australia, and died at the age of 72. John Sibthorp undertook two journeys in the Levant and was also elected a Fellow of the Royal Society. His early death at the age of 38 made him unable to collect the fruits of his endeavours, gain wider recognition, or become known as the father of the natural sciences in the eastern Mediterranean.
Involvement of the extracellular matrix, heparan sulphate proteoglycans, and heparan sulphate degrading enzymes in angiogenesis and metastasis
Authors: Vlodavsky Israel , Miao Hua-Quan , Benezra Miriam , Lider Ofer , Shavit Rachel Bar
Published: November 2023

Basement membranes (BM) and extracellular matrices (ECMs) are the natural substrates upon which cells migrate, proliferate, and differentiate in vivo. Historically, the ECM was regarded as a relatively inert scaffolding which stabilizes the physical structure of tissues. Subsequent studies aimed to elucidate the mode of cellular responses to ECM indicated that the ability of cells to respond to various growth and differentiation factors is determined to a large extent by their shape and orientation and that these are modulated by components of the ECM through interaction with specific transmembrane cell surface integrin receptors (1-4). Studies with mammary gland epithelial cells led to the identification of genes that are dependent upon the ECM for their transcription and to the discovery of ‘ECM-response elements’ (5).
The role of fibroblast growth factors in tumour progression and angiogenesis
Authors: Christofori Gerhard
Published: November 2023

Already in 1939 and 1945 it had been demonstrated that tumours induce the formation of new capillaries from preexisting blood vessels, a process termed angiogenesis (1,2). Subsequently, it was shown that soluble angiogenic factors released by tumours were responsible for this process (3,4). The finding that many of these growth factors bound to heparin allowed the purification and classification of a family of heparin-binding growth factors (5). The prototypes of this family are fibroblast growth factor (FGF) 1 and FGF-2, and they have been studied in great detail in many physiological and pathological processes (reviewed in references 6-10). To date the family has expanded to nine distinct, but closely related family members. Based on their pattern of expression and their biological activities they are thought to be involved in many physiological and pathological processes, including embryonic development, differentiation, cell survival, angiogenesis, oncogenic transformation, and tumour cell proliferation.
Sensory perception and the lateral line system in the clawed frog,Xenopus
Authors: Elepfandt Andreas
Published: November 2023

Xenopus lives in stagnant and often turbid waters and is nocturnal. Correspondingly, the organization of its sensory systems differs from that in terrestrial frogs. Xenopus retains its lateral line system after metamorphosis. By means of this system, Xenopus can analyse single waves as well as waves impinging simultaneously on it.
Underwater acoustics and hearing in the clawed frog, Xenopus
Authors: Elepfandt Andreas
Published: November 2023

Xenopus communicates acoustically in the same way as other frogs but completely under water. This requires that the communication and auditory system matches the properties of underwater sound in shallow waters. The ear shows the basic characteristics of a frog ear, but is modified. The tympanum is a cartilaginous disc beneath the skin, the stapes leaves the tympanic cavity caudally, and the two Eustachian tubes form a joint air-filled canal that connects to the mouth via one medial opening. In Xenopus laevis, males prefer to call from deeper parts of a water body. Their advertisement calls consist of clicks of which the dominant frequency is at 1600-2000 Hz. The hearing range is 200--3900 Hz, with optima at 600 Hz and 1400-1800 Hz. Sound is localized throughout the whole anterior semicircle. Frequency discrimination is found at 400-800 Hz and, with a limen attaining 2%, at 1400-2500 Hz. The latter range encompasses the dominant frequency of the advertisement call. The dominant frequency is constant for any male but differs between males so that the level of frequency discrimination allows for distinction between calling males. Since the calls of larger males tend to have lower dominant frequencies, choice of larger males might thus be possible. Biophysical studies show that the ear responds to sound pressure rather than particle velocity. The most probable mechanism is an air bubble resonance of the air in the Eustachian tubes and possibly the lungs. Tympanic vibration amplitude depends on sound direction, thus forming a basis for sound localization by the animal.
The consequences of no1nadism non-breeding behaviour and biology
Authors: Davies S J J F , Bamford Michael J , Loomes Danika
Published: November 2023

The ostrich, rhea and emu are often described as nomadic. Nomadic birds move from place to place without regard to season or direction. Such species depend on resources that occur rarely at the same site. A continuity of supply can be ensured only if the bird is able to locate successive favourable areas often hundreds of kilometres apart. Successful behaviour for these species is, therefore, success at the location of resources, widely separated in space but juxtaposed in time.
Mating syste1ns and breeding biology
Authors: Davies S J J F , Bamford Michael J , Loomes Danika
Published: November 2023

The reversal of the role of the sexes in incubation and parental c;i1-c is characteristic of all the ratites and tinamous other than the ostrich (Handford and Mares 1985). The female ostrich shares incubation with the male and helps to guard the brood (Siegfried and Frost 197 4); in the other species, except the Stewart I. subspecies of the brown kiwi, the male alone is responsible for incubation and parental care. Occasional reports mention female emus sitting on nests, but these incidents are exceptional; for the most part parental duties are the province of the male alone.
Emu
Authors: Davies S J J F , Bamford Michael J , Loomes Danika
Published: November 2023

One living species, two island species recently exterminated. Bill broad, with the culmen elevated at the base, sloping dmvn to the tip; nostrils in a large membranous groove. Aftershaft as long as main shaft. Clavicles rudimentary. Tail not apparent. Tarsus long, strong, mostly cm’ered in front with reticulated scutes, except near the toes, where a few scutes are transverse. Rear of tarsus covered with rough, projecting scales.
Introduction: current topics in organic crystal chemistry
Authors: Jones D W
Published: November 2023

Unlike many physical methods, for which early applications to organic chemistry have been semi-empirical, X-ray crystallography has long been a major source of specific information about the geometry of the whole molecule inferred or determined by diffraction from the electron density pattern in crystals. Later developments in collection and treatment of X-ray data for structure solution and refinement enabled this approach to be extended to finer details of the electron distribution and of thermal motion of atoms and groups and to be applicable rapidly to larger organic structures. Also, the distinctive contribution of neutron measurements, derived by diffraction by a different atomic scattering mechanism, has been demonstrated more widely, for example in precise location of hydrogen atoms and for combination with X-ray data. Concurrently there have been advances in the complementary approach to calculation by molecular mechanics and other methods of the expected stereochemistry and dimensions of free molecules.
Modelling steroid hormone receptor interactions on the basis of crystallographic and biochemical studies
Authors: Duax W L , Griffin J F
Published: November 2023

Steroid hormones are vital to numerous physiological processes including cell growth, sexual development, maintenance of salt balance and sugar metabolism. Many of these activities are known to be contingent upon the binding of steroids to specific cytosolic protein receptors and the subsequent interaction of the steroid receptor complex with chromatin (Jensen et al., 1962).
Stereochemistry of methyl and methoxy substituents in polycyclic hydrocarbons
Authors: Briant C E , Johnson O , Jones D W , Shaw J D
Published: November 2023

The molecular sites of methyl, methoxy and other simple substituents can have a marked influence on the biological activity of polycyclic aromatic hydrocarbons (PAH). Thus the carcinogenic activities of the monomethyl-(MBA), dimethyl-(DMBA) and polymethylbenz[a]anthracenes range from the negligible in 2-MBA or slight in-1,12-DMBA to the extremely potent in 7-MBA or 7,12-DMBA, even though the structure differences are relatively small. Much the same applies to substitution in phenanthrenes (Johnson et al., 1989), benzfluoranthenes and other PAH.
Aryloxide-aluminium π-bonding in the π-face selectivity of co-ordinated ketones towards nucleophilic attack
Authors: Barron Andrew R
Published: November 2023

One of the most important c-c bond formation reactions in organic synthesis is nucleophilic addition to organo-carbonyl groups. A significant development in this area has been the use of the bulky organoaluminum compound, A1Me(BHT)2 (1), for controlling the -face selectivity of carbonyl moieties towards nucleophilic addition (Maruoka, Itoh, Yamamoto, 1985; Maruoka, Itoh, Sakuria, Yamamoto, 1988).
High speed, high resolution data collection on spinach Rubisco using a Weissenberg camera at the Photon Factory
Authors: Andersson LA , Clifton I J , Fülöp, V , Hajdu J
Published: November 2023

High resolution data collection on crystals with large unit cells can be a difficult problem. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from plants is a hexadecamer (Mw = 550,000) consisting of eight large (L) and eight small (S) polypeptide chains. The structure of the enzyme complexed with a transition state analogue has been solved to 2.4 Åresolution (Andersson et al. 1989; Knight et al. 1990). The crystals belong to space group C222 with unit cell parameters of a=157.2 Å, b=157.2 Å and c=201.3 Å (Andersson & Branden, 1984), and diffract to better than 1.5 Å resolution. Diffraction data to 1.5 Å resolution are extremely difficult to record from crystals with large unit cells. Many of the high resolution reflections would be overlapping with each other on a flat film during a 1.0 degree rotation of the crystal. Much smaller oscillation ranges are impractical due to the nature of film processing. To overcome these difficulties, the use of a giant Weissenberg camera (Sakabe, 1983) was explored.
On the limitations of the Laue method when applied to crystals of macromolecules
Authors: Hajdu J , Alma S C , Farber G K , Prater J K , Petsko G A , Wakatsuki S , Clifton, l.J , Fülöp V
Published: November 2023

The Laue method in combination with a synchrotron source can produce large amounts of data very rapidly. This technique offers fast data collection which in many cases eliminates the time dependent component from radiation damage. The method suffers from two principal problems: The difficulty in obtaining low resolution data from Laue photographs. This arises from geometrical restrictions inherent in Laue diffraction, and from computational difficulties when separating harmonic overlaps and applying wavelength dependent corrections to low resolution singlets. The consequence of this is a “low resolution hole” in the data set. The loss of low resolution data poses difficulties in identifying atoms with high B-factors in the structure.
CIF standard data
Authors: Hall S R
Published: November 2023

Most existing procedures for computer archiving use a ‘fixed format’ file which has a data structure determined by specific data requirements. A fixed format file provides for fast access but the data structure cannot be modified without the need to reformat existing files. Another type of file is based on ‘pre-defined free formats’. This approach does not restrict data to specific positions in the file, and uses ‘data keys’ to aid in data recognition. Crystallographic examples of this type of format are the BCCAB archive file of the Cambridge Data Centre and the Standard Crystallographic File Structure (Brown, 1988). The relative inflexibility of both these traditional archival approaches tends to limit the rapid exchange of data, even within a field where the basic data requirements are the same (e.g. molecular structure). This problem becomes particularly acute if the number and nature of data types changes rapidly and continually. This is becoming the case in computer-intensive disciplines, such as crystallography, which support a vast repertoire of specialized and ‘local’ file formats. The diversity of file formats is tolerable when electronic data transfer is infrequent and processing speeds require that file formats be finely tuned to a specific application. Rapid increases in computing power and in computer networks has signalled an end to this rationale. In the era of widespread data exchange, global databases, electronic mail and electronic publication submission, there is a critical need for a general, flexible and extensible file format.
Recent advances in the PROTEIN program system for the X-ray structure analysis of biological macromolecules
Authors: Steigemann W
Published: November 2023

The PROTEIN program package has been designed as a compact system for the X-ray structure analysis of proteins. With the objective in mind of providing user-friendliness in terms of functionality, generality, common file structure, and format free command input within a unified program package, the program system has become wide spread within the crystallographic community over its 15 years of existence (some 150 installations worldwide). After a few years of minor improvements a major step in the development has been taken within the last year. Version 3 of the package has been launched with an enhanced file structure (provision for standard deviations of observations, several phase sets, anisotropic scaling, etc.) and with a functional extension by incorporating and improving previously separate supplementary programs. In particular, these comprise phase combination by use of Hendrickson-Lattman coefficients, statistics on the quality of phase information or their combination, a very general structure factor setup program (for any kind of map), data screening of outliers of derivative data on the basis of comparison with native data, direct support of PROTEIN like map files from the real space search routines, etc.
Improved productivity through crystallographic packages
Authors: Frenz B
Published: November 2023

Any crystallographic software system must contain the essentials: data reduction, structure solution, structure refinement, derived results. However, because of the variance in crystals, chemical composition, molecular weight, and space group, a complete system must include a plethora of optional functions that extend beyond the basics, in a sense, the more functions the better because one never knows what crystallographic problems will appear on the horizon. Table I gives a checklist of functions that would be useful in a complete system. To my knowledge no single package contains all the items listed, however the Personal SDP includes 92% of them.
Computational protein sequence analysis as an aid in solving protein structure
Authors: Sibbald P R
Published: November 2023

The analysis of protein sequences can assist in solving protein structures. Here an overview of various tools and methods is given and their uses and limitations are discussed. This paper is written for experimentalists who want to solve protein structures and are interested in analysing protein sequences to assist in the task. Practical aspects of the problem are emphasized, concentrating on existing databases and useful methods rather than on algorithms or theoretical considerations. The following questions are addressed:
Chemistry in relation to toxicity and to risks of exposure to organotin compounds
Authors: Aldridge W N
Published: November 2023

Toxicity is a multi-faceted property; between exposure of the organism and the expression of toxicity, as signs or symptoms of poisoning, are many stages which have different mechanisms and different doseresponse and structure-activity relationships. Central to an understanding of toxicity is the initiating reaction(s) of the toxic chemical with important macromolecules (targets) which causes changes in the controlling systems within the affected cell. Toxicity is therefore a chemical problem in biology.
Ionophoretic activity and biological effects of triorganotin compounds
Authors: Selwyn M J
Published: November 2023

The toxicity of triorganotin compounds is considered in relation to their hydrophobicity, inhibition of oxidative phosphorylation by blocking H --conduction through the F component of the mitochondrial ATPase, inhibition of other enzymes, and catalysis of C1- /OH- exchange across membranes.
High quality silicon nitride powder derived from Malaysian rice husks
Authors: Rahman Ismail Abdul , Riley Frank L
Published: November 2023

a-Silicon nitride powder has been prepared by nitriding pyrolysed rice husks incorporated with 4 per cent pre-formed silicon nitride at a temperature of about 1450°C and under a 95 per cent N/5 per cent H atmosphere. The silicon nitride powder is obtained in the form of equiaxed, sub-micrometer, and uniformly distributed particles. A material evaluation based on its powder characteristics, hot-pressing behaviour, and other properties shows that this silicon nitride is of a good quality compared to that of the best currently available commercial powders. Thus, rice husks are a good, cheap, and readily available raw material for the production of high quality silicon nitride.
A silicon semiconductor strain device for acoustic power measurement
Authors: Singh V R , Prasad Awadhesh
Published: November 2023

The effect of ultrasonic stress on the chemical properties of a silicon strain device has been studied. Possible chemical mechanisms which account for crystallographic orientation and resistivity are discussed in some detail. The sensitivity of the silicon strain gauge to ultrasonic stress shows a linear dependence. Radiation pressures from ultrasonic therapy sources have been measured with the silicon strain gauge transducer based on the calibration of the electrical output of the device against the acoustic power outputs of standard ultrasonic sources. An ultrasonic power meter has thus been developed for potential commercial use.
Studies on the yields of silylation reactions of mineral silicates
Authors: Khan M Mazhar Bashar , Ali Saqib , Zia Irshad A , Iqbal M
Published: November 2023

The trimethylsilylation reaction is of interest from the viewpoint of structural determination of silicates, and certain mineral silicates undergo this reaction in the presence of a mixture of concentrated hydrochloric acid, isopropanol, and hexamethyldisiloxane. , Cations present in the mineral are initially leached out by hydrochloric acid and the resulting silanol (Si-OH) groups then reacted with silylating reagent (trimethylsilyl chloride) to give trimethylsilylated silicates. ·6 The purpose of the present study was to explore the effect of different metal ions on the silylation of mineral silicates, and to optimize the reaction conditions for high-yield preparations of macromolecules for possible use as industrial chemicals.
Copolymerization of dimethyldivinylsilane
Authors: Oku Jun-ichi , Hasegawa Takashi , Takaki Mikio
Published: November 2023

The anionic polymerization of monovinylsilanes was first reported in 1963, and a brief report on the polymerization of dimethyldivinylsilane (DMDVS) which appeared in 1969 described a soluble polymer which was obtained with n-butyllithium as initiator (molar ratio monomer:initiator = 9:1). However, no detailed analyses of the polymer were carried out by the authors.
Synthesis of coenzyme On and quinonoid antibiotics by using allyltrialkyltins: control of regio- and stereochemistry in fluxional pentadienyltins and their application to chiral anthracyclinone synthesis
Authors: Maruyama Kazuhiro , Naruta Yoshinori , Nishigaichi, Yutaka , Tachikawa Noboru
Published: November 2023

Pentadienyl anions, unsymmetrically substituted at the 2-position, were trapped using Me SiCI and Me SnCI to give the corresponding pentadienylmetals which show marked differences in their regioselectivity. The tin electrophile gave (Z)-2-substituted isomers in high selectivity up to 96 per cent regardless of the nature of the substituents. On the other hand, the silicon electrophile gave (Z)-4-substituted products with moderate to high selectivity. The difference is explicable in terms of the preferential 1,5-Me Sn sigmatropic shift in the pentadienyltin systems towards the thermodynamically more stable s-trans isomers.
Synthesis and X-ray structural characterization of novel doubly asymmetric 8-dimethylaminonaphthyl(― )-menthylorganotin compounds
Authors: Schumann Herbert , Wassermann, Birgit Corinna , Pickardt Joachim
Published: November 2023

Menthylmethyltin dibromide (1) reacts with 8-dimethylaminonaphthyllithium etherate to give the doubly asymmetric 8-dimethylaminonaphthyl-(― )-menthylmethyltin bromide (2), in which a chiral carbon atom of an optically active ligand is bound to a chiral tin centre. The molecular structure of 2 shows a diastereomerically pure compound with an absolute configuration of Rsn at the pentacoordinated tin atom.
Crystal structure of tri-n-butyltin(IV) N-methyl-N-phenyldithiocarbamylacetate, (n-C4H9)3SnOC(O)CH2SC(S)N(CH3) (C6Hs)
Authors: Weng Ng Seik , Wei Chen , Das V G Kumar , Keong, Yap Chee , Butcher Ray J
Published: November 2023

Triorganotin carboxylate esters display several structural variations: triphenyltin thiophene-2-carboxylate is a monomeric molecule, triphenyltin pyridine- 3-carboxylate a flat, pyridyl-bridged polymer and triphenyltin 8-quinolyloxyacetate a water-coordinated, hydrogen-bonded helical chain; the carboxyl oxygen is not involved in either intra- or intermolecular coordination to tin in the three compounds. On the other hand, triphenyltin chloroacetate and triphenyltin 3-benzoylpropionate are carboxylate-bridged, a feature common to triorganotin esters whose carboxylate group is an acetate derivative. In continuation of our studies on triorganotin carboxylates, we report the crystal structure of tri-n-butyltin N-methyl-N-phenyldithiocarbamylacetate.
Multiple-Quantum Transitions
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander
Published: November 2023

In the past, multiple-quantum transitions have often been neglected in favour of the more easily accessible single-quantum transitions. Many traditional texts on the practical aspects of magnetic resonance hardly mention the existence of the numerous stepbrothers of the one-quantum transitions. Although it is possible to observe multiple-quantum transitions by conventional slow-passage techniques, it is a thorny path and few spectroscopists have ventured to animate the sleeping beauty. Some of the brave scientists were Yatsiv (5.1) and Freeman, Anderson, and Reilly (5.2).
Epitome Of Quantum Mechanics
Authors: Goldman Maurice
Published: November 2023

As stated in the preface, it is only through the use of quantum mechanics that one can get a real understanding of the working of the sophisticated methods that turned high-resolution NMR into a fundamental and powerful tool for the investigation of molecules, especially in the liquid state. However useful, the classical and naive quantum descriptions given in Chapter 1 suffice only for interpreting the simplest version of NMR spectroscopy, namely the resonance spectra obtained either by the CW method or by the Fourier transform of the FID following a single r.f. pulse. As regards methods such as 2D spectroscopy, these descriptions are fundamentally inadequate and provide at best a qualitative and more-or-less intuitive feeling of what happens, very often with serious conceptual difficulties.