bluuebunny/crossref_metadata_2025 huggingface dataset:
Immune system of Xenopus: T cell biology
Authors: Horton John D , Horton Trudy L , Ritchie Pamela
Published: November 2023

Evidence for T and B lymphocyte populations in Xenopus is reviewed, and attention is focused on the recent creation of monoclonal antibodies that identify T cell surface markers. A second section summarizes evidence for T helper and T cytotoxic lymphocytes and their genetic restriction, discusses the role of T cells in transplantation immunity, and outlines studies on T cell-derived cytokines. A third section considers the biochemistry, cell distribution and ontogeny of Xenopus major histocompatibility com¬ plex (MHC) proteins; implications for T cell functioning of the differences in MHC antigen expression between larvae and adults are discussed. The role of the thymus in T cell development is then dealt with in detail. After considering the embryological origins of thymic lymphocytes, describing thymus histogenesis and discussing T cell changes during ontogeny, the possibility of extrathymic development of some ‘T-like’ cells is discussed in the light of recent flow cytometric studies on early-thymectomized (Tx) Xenopus. This fourth section also describes experiments probing the role of the thymus in establishing negative and positive selection of T-lineage lymphocytes. The final section deals with establishment and characterization of peripheral tolerance, following grafting of larvae with allogeneic tissues, and discusses immunoregulatory events occurring during metamorphosis.
The fossil record of the Pipidae
Authors: Baez Ana Maria
Published: November 2023

Pipids have a relatively good fossil record, providing evidence of their evolutionary diversification. The oldest remains referred to this well-corroborated monophyletic group are from the Lower Cretaceous (around 120 Ma) of the Near East. Although their referral to the Pipidae may be questioned, they document the presence of primitive pipoids in the northern margin of Gondwana. All other fossils that clearly belong to this family have been found either in Africa or in South America, where they occur today. Moreover, their former geographical distribution on these continents was more extensive than is their current distribution.
Phylogenetic relationships of the ‘Agkistrodon complex ‘ based on mitochondrial DNA sequence data
Authors: Parkinson Christopher L , Moody Scott M , Ahlquist Ion E
Published: November 2023

We investigated phylogenetic relationships among 15 species of pitvipers commonly known as the ‘Agkistrodon complex ‘ or the tribe Agkistrodontini. We sequenced a 505 base-pair region of the mitochondrial 16S ribosomal DNA for all genera of this group, including all three New World species of the genus Agkistrodon and four members of the Old World Agkistrodon, to test the monophyly of this genus. Results indicate that Agkistrodon is paraphyletic, therefore the genus Gloydius should be used for the Old World members. The genera Calloselasma, Deinagkistrodon and Hypnale are separate lineages, thus their status as genera is upheld. The tribe Agkistrodontini is not valid and the name should be suppressed.
New perspectives on the evolution of south-east Asian pitvipers (genus )Trimeresurus from molecular studies
Authors: Malhotra Anita , Thorpe Rogers.
Published: November 2023

The genus Trimeresurus contains about 36 species, several of which are remarkably similar in superficial appearance, and it is unclear whether this similarity relates to phylogenetic relationships or to ecological convergence. Whatever the cause, it has resulted in considerable confusion which hinders the understanding of the evolution o:f the genus by biologists as well the advancement of snakebite treatment by medical workers. Our ongoing study of this group (part of a larger study of the systematics of medically significant snakes) focuses on a core group of species (T. albolabris, T. popeorum, T. stejnegeri, T. erythrurus, T. macrops) known to be or potentially sympatric in Thailand and adjacent areas and involves the use of multivariate morphometry and mitochondrial DNA analysis to study both inter- and intraspecific relationships. We propose a preliminary phylogenetic hypothesis for a set of species based on PCR-RFLP of the cytochrome b gene of mitochondrial DNA and discuss this in relation to its ability to shed light on morphological evolution in the genus. We then illustrate geographic variation in morphology of T. albolabris, a species with a large range, and relate this to current subspecies and to the phylogenetic history of populations as revealed by cytochrome b sequencing. Mantel tests are used to evaluate various causal relationships.
Cassowaries
Authors: Davies S J J F , Bamford Michael J , Loomes Danika
Published: November 2023

Large, cursorial, flightless birds from northern Australia, New Guinea and adjacent islands (to which they were probably introduced). Bill as long as head, compressed, with the culmen curved to the tip. Nostrils in broad membranous groove in the middle of the bill. Head ornamented with an elevated helmet; head and neck bare, often brightly coloured, with wattles on the neck. Wings rudimentary, with 5-6 strong rounded shafts without webs; tail not apparent.
Introduction to Heterogeneous Catalysts
Authors: Sleight Arthur W
Published: November 2023

An aspect of inorganic solids that has frequently been neglected by solid state chemists is the catalytic property. The reason for this neglect can be primarily attributed to the great difficulty of achieving a detailed understanding of surface structure and reactivity. Certainly, it has been true that reliable mechanistic information on heterogeneously catalysed reactions is rarely achieved. Even on an empirical level, good correlations between catalytic properties and the chemistry of the catalyst itself have been largely lacking. Fortunately, advanced techniques and instrumentation for microstructure and surface studies are now allowing rapid strides to be made in the area of heterogeneous catalysis. Indeed, many obvious and potentially highly revealing experiments within our grasp are waiting to be done. Surface properties of solids are of paramount importance for heterogeneous catalysis. One would like to know the active site density on each crystallographic surface of a solid, and one would also like to know if these active sites are related to dangling bonds due to coordinatively unsaturated surface sites or if they are related to special defects. In a few cases, we are beginning to obtain answers to these questions, and the rate of progress is increasing.
Scissor-type hosts: molecular design and inclusion behaviour
Authors: Weber Edwin
Published: November 2023

It is clear that clathrates and related lattice inclusion compounds are substances now less commonly found by accident, but are more often the products of rational design and synthesis. This is witnessed by a number of examples in the recent literature. Developments are mostly based on a particular overall shape and significant geometry of the so-called host molecule. Examples are the ‘hexa-hosts’ or ‘spiders’, ‘paddle-wheel’ hosts, ‘wheel-and-axle’ hosts, ‘wine cup’ hosts,‘tub’-like, ‘scissor’-type, and ‘roof-shaped hosts. Since the objects connected with the approximate shape of these host molecules have a well-defined symmetry, relationships between host symmetry and clathrate formation are obvious. Thus, projection to a molecule possessing a given symmetry operation is another leading idea of recent host design. On the other hand, it has been realized that directed formation of stable and highly selective clathrates also requires specific binding forces between host and guest stronger than van der Waals interactions. Consequently, a concept based on specific host-guest interactions of dipolar and/or coordinative nature was developed.
Intercalates of zirconium phosphates and phosphonates
Authors: Alberti Giulio , Costantino Umberto
Published: November 2023

Tetravalent metals such as Zr, Ti, Sn, Ce, Th, etc. can be bound to oxygens belonging to XO4 and/or RXO3 groups (X = pentavalent element; R =inorganic or organic group such as -H, -OH, -CH3, -C6H5, etc.) and from such a combination many fibrous, layered, and three-dimensional structures can be obtained. Furthermore, if the oxygens belong to R(XO3)i groups, very interesting layered structures, in which the layers are covalently bonded by the R group acting as pillars, may be formed. The structural features, physicochemical properties, and applications of this rapidly growing class of compounds have been the subject of chapters in books and recent reviews.1-10 Owing to their importance in intercalation and insertion chemistry, we shall in this chapter be concerned almost exclusively with layered structures, including those having layers covalently bonded by R pillars. As regards fibrous and three-dimensional structures, therefore, the interested reader is referred to a number of reviews29 and papers11-14 on these subjects.
Recent advances in the X-ray analysis of cyclodextrin complexes
Authors: Harata Kazuaki
Published: November 2023

Cyclodextrins are cyclic oligosaccharides consisting of six or more a-1,4-linked o-glucose units. These bucket-shaped macrocyclic molecules have a cylindrical cavity with a diameter larger than 5 A and a depth of7-8 A. The inside wall of the macrocycle is comprised of many methylene and methine groups, whereas at both ends of the cavity hydroxy groups are found in a circular arrangement. Therefore, the cyclodextrin cavity exhibits hydrophobic character and favourably accommodates the hydrophobic portion of the guest. Cyclodextrins form inclusion complexes rather nonspecifically with a wide variety of guests of suitable size and shape. Because of the rigid structure of cyclodextrin molecules, the size and shape of the interior cavity are strictly confined by the number of constituent glucose units and complex formation is highly stereoselective, that is, guest molecules or groups should fit into the host cavity, even if only partially.
Chemical sensors
Authors: Lockhart Joyce C
Published: November 2023

A chemical Rip van Winkle awakening today from his extended sleep and examining the chemical scene, would surely be most struck by the chemist's ability to design molecules for a purpose. The able chemist can today essentially design and synthesize molecules to order. For the current generation of chemists the new horizons are the multi-molecular assemblies which can provide analogues of a biological unit. In the area of chemical sensors, the syntheses which chemists are struggling to effect should unite a chemical entity capable of recognition with a signal-processing entity capable of transmitting a signal consequent upon the recognition.
The Colours of Life
Authors: Milgrom Lionel R
Published: November 2023

Why are leaves green and blood red? The answer lies with one family of pigments, the porphyrins and their relatives. These pigments are also responsible for the fundamental energetic processes that make life as we know it possible. The properties of these colorful molecules are now being investigated for use in a wide range of applications, from cancer therapy to microelectronics. The Colours of Life is intended to be an introduction to the porphyrins and their role in life.
Reliability of structure determinations by microwave spectroscopy
Authors: Eijck Bouke P van
Published: November 2023

The microwave region was the first part of the electromagnetic spectrum where essentially monochromatic radiation sources were used for molecular spectroscopy. This field was opened in the years around 1950 after the development of radar techniques in the second world war. Thus it became possible to measure the frequencies of rotational transitions in gaseous substances with great precision. A typical wavelength would be 1 cm, corresponding to a frequency of 30 000 MHz. At a typical gas pressure of a few Pa the lines are quite narrow and a transition frequency can easily be measured within 0.1 MHz (Fig. 3.1). Nowadays the frequency range which is available has been considerably extended. Millimeter wave spectra can be obtained relatively easily, and laser techniques have made many infrared measurements nearly as accurate as microwave ones. Still, as far as our interest in structure determinations is concerned, the interpretation of the results uses the same methods. We shall see that, unfortunately, much of the accuracy is lost when one tries to extract structural information from the observed transition frequencies.
Quantum mechanical determination of static and dynamic structure
Authors: Boggs James E
Published: November 2023

Recent years have witnessed an explosive proliferation in the use of all kinds of quantum chemical methods to evaluate molecular structures and vibrational dynamics. Semiempirical procedures have made major contributions in areas such as understanding the mechanisms of drug-substrate interactions, interpretation of organic mechanisms by study of reaction pathways and transition states, and in other applications where relatively rapid computation of molecular properties at a medium level of accuracy provides the needed information. However, this book is directed toward the experimental and theoretical methods that can provide structural information at the highest levels of accuracy and reliability so only ab initio theoretical methods or such methods with the computed parameters modified by minor empirical corrections are considered here. Accuracy in bond lengths to a few thousandths of an angstrom and in bond angles to a few tenths of a degree may be taken as an appropriate goal.
Amino acids, peptides, and proteins
Authors: Bensasson R v. , Land E J , Truscott T G
Published: November 2023

Increasing interest in the photo- and radiation chemistry of proteins is due to: the effects of irradiation on food proteins (see, for example, Swallow 1991); the increasing recognition of radical induced biochemical injury via reactions with proteins (Willson et al. 1985); the recognition of the role of electron transfer reactions involving intramolecular processes in proteins (see, for example, McLendon 1988; Prutz et al. 1989) and the application of Marcus theory to such electron transfer processes (see, for example, Bertrand 1991, Faraggi and Klapper 1991 and references given in Section 6.8); studies of two photon absorption processes (see, for example, Nikogosyan and Gorner 1992); a more detailed understanding of protein conformations and dynamics probed by tryptophan triplet (Geacintov and Brenner 1989); photo-deligandation in haem proteins, see, for example, Hochstrasser and Johnson 1988; Frauenfelder etal. 1991; the role of a tyrosyl residue in re-reducing the oxidized chlorophyll special pairs in photosystem 2 of photosynthesis (P680—see Chapter 7) and subsequently oxidizing the manganese cluster (see, for example, Mathis etal. 1989); and crosslinking of DNA to proteins (see, for example, Simic and Dizdaroglu 1985) Nearly half the dry weight of living material is composed of protein (from ‘proteios’ meaning, in Greek, of the first rank). Many thousands of protein structures have now been established and the role of proteins and enzymes extends to nearly all biological processes.
The World of Physical Chemistry
Authors: Laidler Keith J
Published: November 2023

This book might have been entitled ‘A History of Physical Chemistry’, which to some extent it is. I am not, however, a historian, and my object has been somewhat different from that of a historian. I wanted primarily to give scientists some insight into how one important branch of physical science has developed. At the same time I have tried to write the book in such a way that historians of science who are not also scientists may find the book useful, even though they may well want to skip over some of the early material with which they will be familiar, and perhaps some of the more mathematical parts.A science like physical chemistry is not necessarily best taught in the first instance by a purely historical approach. A historical approach to science does, however, have important uses. For one thing, the teaching of science can be more effective if the teacher has some knowledge of its history. An account of some personal incident that occurred during the course of scientific work can greatly arouse the interest of students. I have found, for instance, that the story of Arrhenius’s difficulties with his Ph.D. examiners always seems to go down well with students, and seems to make them think that electrolytic dissociation is perhaps not such a dull subject after all.
The Chemical Synthesis of Peptides
Authors: Jones John
Published: November 2023

Peptides have diverse applications and potential in medicine: the regulation of fertility; the control of pain; the stimulation of growth; the therapy of cancer, cardiovascular problems, connective tissue diseases, digestive disorders, mental illness, and infections by microbial or viral agents. The preparation of such compounds by manipulating biological systems (genetic engineering) is an increasingly sophisticated art, but each case requires developmental work, and the approach is at present almost powerless with structural types unknown to Nature. Chemical synthesis, on the other hand, is in principle applicable to any target, and is likely to remain very important in the peptide area for the forseeable future. At the present time the output of the primary literature on the subject is nearly a thousand publications a year, and increasing relentlessly. The term peptide is interpreted liberally, as embracing not only conventional sequences of up to a few dozen proteinogenic amino acids but also extending to protein-scale molecules and structures comprising other residues or unusual features, for example cyclopeptides and conjugated peptides. Emphasis throughout is on the chemical principles behind the more important methods, which are treated within a modern mechanistic framework and illustrated with carefully selected case studies. This book provides a critical, concise, and up-to-date survey of the area. It is aimed principally at the graduate level, especially for those starting in the field, but it should also be of interest to experienced practitioners and advanced undergraduates.
Strategy and tactics
Authors: Jones John
Published: November 2023

The last four chapters have presented a summary catalogue of the principal methods by which the various individual reactions and stages of a peptide synthesis may be carried out. It is now necessary to consider how a coherent plan can be drawn up, and the appropriate methods chosen, for a synthesis of many stages.
Solid phase peptide synthesis
Authors: Jones John
Published: November 2023

The beautifully simple idea of solid phase peptide synthesis was first detailed* by Merrifield in 1963, in a publication which, unusually for an important modern chemical paper, bore his name as sole author. The principle is outlined in Scheme 9.1.
Introduction
Authors: Gray Peter , Scott Stephen K
Published: November 2023

This is a book about chemical kinetics--not necessarily the most familiar aspects of that subject, but nevertheless the various phenomena to be described arise primarily because reactions occur at finite rates, and different reactions may occur at different rates. Before proceeding along our kinetics course, however, it is worth while examining what information we can gain from thermodynamics. For most of us, the familiar aspects of thermodynamics are those dealing with systems at chemical equilibrium. Then we can ‘use’ concepts such as enthalpy and entropy to place strong restrictions on the final equilibrium composition attained from a given set of initial reactant concentrations.
Nuclear Magnetic Resonance Imaging
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander
Published: November 2023

After its successful application in physics, chemistry, and molecular biology, NMR is now beginning to play a vital role in the field of clinical medicine. Many fruitful applications have emerged, like investigations of whole tissue in vitro and in vivo to trace out biological processes. But the most promising application of NMR in medicine is the non-invasive imaging of entire biological organisms. The first experimental demonstration of the feasibility of macroscopic imaging by NMR was given by Lauterbur in 1972 (10.1, 10.2). The use of NMR for investigations of the human body, particularly for cancer detection, was advocated first by Damadian (10.3, 10.4).
Coupled systems
Authors: Scott Stephen K
Published: November 2023

In the previous chapter we looked at the range of behaviour exhibited by chemical systems exposed to some periodic external input. A related experimental arrangement is that in which one or more reactors are coupled together in some way. Then oscillations in one or more of the individual units might provide a periodic stimulus to the others. In this case, however, there is an extra subtlety as the other units can ‘fight back in the sense that their response will also influence the first.
The Belousov-Zhabotinskii and other solution-phase reactions
Authors: Scott Stephen K
Published: November 2023

The Belousov-Zhabotinskii reactions is relatively widely known for its long trains of oscillations in closed vessels (Belousov 1951, 1958; Zhabotinskii 1964a,b, 1985; Zhabotinskii 1987; Zhabotinskii et al. 1982). Although there has been much recent debate about some detailed aspects, the basic mechanism appears to be well established. A relatively simple model, the ‘Oregonator’, has proven remarkably successful at reproducing and predicting the observed behaviour in a wide range of experimental situations, even with independently determined rate data. We will return to mechanistic and modelling questions below, after introducing the experimental phenomena: comprehensive accounts of such issues as bromide ion control, the role of the catalyst, values of the rate constants, etc. can be found in the multiauthor work edited by Field and Burger (1985) or the recent papers by Field and Forsterling (1986), Noyes (1986), Ruoff et al. (1988), and Noyes et al. (1989). Here, we concentrate on the behaviour in well-stirred flow reactors (CSTRs).
Gas-phase reactions
Authors: Scott Stephen K
Published: November 2023

The existence of oscillations and the potential for chaotic behaviour in gas-phase reactions have received a much less widespread coverage than their solution-phase counterparts. An introduction to this topic can be found in Gray and Scott (1985), Griffiths (1985a), and in the companion to this book (Gray and Scott 1990). Recent reviews have also been given by Griffiths (1985b, 1986) and Griffiths and Scott (1987).
Reaction of alkynes with organometallic reagents
Authors: Negishi Ei-Ichi , Choueiry Daniele
Published: November 2023

Hydrometallation and carbometallation may be defined as additions of hydrogen-metal and carbon-metal bonds, respectively, to carbon-carbon multiple bonds. Of interest here are those involving alkynes (Scheme 7.1). Such addition reactions can be syn-, anti-, and non-stereoselective.
Summary of alkene syntheses
Authors: Westwell Andrew D , Williams Jonathan M J
Published: November 2023

Each previous chapter in this book has been devoted to particular methods for the synthesis of alkenes, and has included experimental protocols which provide details for the preparation of alkenes. These chapters have broadly been arranged into the types of starting material which are required. There have been alkene syntheses from two components, from single C-C bonds, from triple C-C bonds, and from other alkenes.
Pressure determination
Authors: Holzapfel W B
Published: November 2023

Modern methods of pressure measurement began as early as 1643 with the development of the mercury-column manometer by Torricelli, which are still used in some antique domestic barometers. The unit 1 Torr = 1 mmHg = 133.322 Pa (by definition exact) is a reminder of this almost outdated technique.
Electrophoresis of proteins under high hydrostatic pressures
Authors: Masson Patrick
Published: November 2023

Elevated pressures can induce functional and structural alterations of proteins. The effects of pressure are governed by Le Chatelier’s principle. According to this principle, an increase in pressure favours processes which reduce the overall volume of the system, and conversely increases in pressure inhibit processes which increase the volume. The effects of pressure on proteins depend on the relative contribution of the intramolecular forces which determine their stability and functions. Ionic interactions and hydrophobic interactions are disrupted by pressure. On the other hand, stacking interactions between aromatic rings and charge-transfer interactions are reinforced by pressure. Hydrogen bonds are almost insensitive to pressure. Thus, pressure acts on the secondary, tertiary, and quaternary structure of proteins. The extent and the reversibility, or irreversibility, of pressure effects depend on the pressure range, the rate of compression, and the duration of exposure to increased pressures. These effects are also influenced by other environmental parameters, such as the temperature, the pH, the solvent, and the composition of the medium.
Thia oxa-thia and aza-thia crowns
Authors: Parker David
Published: November 2023

The synthesis of macrocyclic thia crown ethers dates back long before the first reports of the synthesis of Pedersen’s oxa crown ethers. Back in 1920, Ray1 reported the synthesis of 1,4,7-trithiacyclononane, 1, which is also known by the acronym [9]-S3, involving reaction of potassium hydrogen sulfide with dibromoethane. In 1934, Meadow and Reid described the isolation of 1,4,7,10,13,16-hexathiacyclooctadecane ([18]-S6), 2, albeit in a yield of 1.7%. It has also been appreciated for some time that in order to avoid undesirable oligomerisations, the co-cyclisation of an acyclic dithiol with an alkyl dihalide should be carried out under conditions of high dilution. Workers at Kodak, for example, described in 1961 the synthesis of [18]-S204, 3, in a 59% yield by working at high dilution in ethanol.
Crown ethers
Authors: Amabilino David B , Preece Jon A , Fraser Stoddart J
Published: November 2023

Crown ethers are perhaps the most widely used family of host compounds in supramolecular chemistry-the chemistry of the non-covalent bond. The fortuitous discovery of the macrocyclic polyethers by Pedersen in 1967 laid the foundation for an exhaustive study of their preparation and complexing abilities, primarily with metal cations but also with neutral and even anionic species.5 Moreover, the metal ions which are complexed by crown ethers can also be utilised as templates for their formation.
Calixarenes
Authors: Arduini Arturo , Casnati Alessandro
Published: November 2023

The term calix[n]arenes indicates a class of phenolic metacyclophanes derived from the condensation of phenols and aldehydes. The name was coined by Gutsche and derives from the Latin ‘calix’ because of the vase-like structure that these macrocycles assume when all the aromatic rings are oriented in the same direction. The bracketed number indicates the number of aromatic rings and hence defines the size of the macrocycle. To identify the phenol from which the calixarene is derived, the para substituent is designated by name.
Transition metal-tern plated formation of [2]-catenanes and [2]-rotaxanes
Authors: Chambron J -C , Chardon-Noblat S , Dietrich-Buchecker C O , Heitz V , Sauvage J -P
Published: November 2023

Catenanes and rotaxanes have been considered together for decades although the topologically different nature of each system has been clearly stated only in a limited number of discussions. These molecules are made up of two components kept together by a mechanical link: in a catenane, two macrocycles are interlocked, whereas in a rotaxane a macrocycle is threaded on to a dumbbell-shaped molecular component whose stoppers are large enough so as to prevent unthreading of the ring (Fig. 9.1). Topologically speaking, catenanes are non-planar molecules, since they cannot be represented in a plane without two crossings at least. On the contrary, rotaxanes are planar molecules: it is easy to imagine the stretching of the chemical bonds of the ring so as to allow the blocking groups to pass through the ring and thus to obtain the cyclic and linear fragments separately.
The evolution of organic compounds
Authors: Williams R J P , Da Silva J J R Frausto
Published: November 2023

The designation ‘organic’, carrying its original sense of ‘life’ chemistry, has a broad meaning still centrally based on the element carbon in association with H, N and 0, in both synthetic and degradative reactions. However, included under this heading today, with the chemistry of these four light elements, is some of the chemistry associated with heavier non-metals and that of some metals, when it overlaps with organometallic chemistry. Due to the diversity of organic chemistry, summarising it (especially in relation to life) is an awesome task, but it is necessary to do so in order to uncover some special principles of element association with carbon. It also leads forward to biological chemistry in the development of life, a combination of organic with much inorganic chemistry. Organic chemistry with inorganic chemistry is not simply linked to biological chemistry however, since this requires a much wider vision and an organisational ingredient which we leave until Chapters 10-13. In essence we have to show in this chapter the myriad ways of putting together several of each of the atoms C, H, N and O using single, double and triple bonds, as well as including S, P, Se and halogens in some compounds, the ways in which synthesis can be managed, and the ensuing properties of the resultant compounds. This would not be a problem peculiar to these elements but for the fact that, while the organic compounds of carbon are thermodynamically unstable (Fig. 9.1), they are kinetically stable in oxygen (air) and water for long periods, which gives them their particular importance in living systems and subsequently in some of man’s industries.
Organisation in advanced organi•sms
Authors: Williams R J P , Da Silva J J R Frausto
Published: November 2023

In Chapter 12 we have shown that the development of organisms from 3 to 1 x 109 years ago caused an increasing dioxygen partial pressure and gradually changed the availability of many elements on Earth. Many organisms themselves then altered and/or adjusted their uptake and incorporation mechanisms for elements and so became analytically different in a changed environment (Fig. 13 .1). These changes in element use led eventually to a massive development of life in the form of multicellular aerobic organisms. The fact that many of these organisms could build hard mineral structures has left us with a remarkably good fossil record about them but only dating from less than 1 x 109 years ago (Figs 12.6 and 12. 7). The evolutionary development of the chemistry was matched by changes in the shape and function of single cells and also by the appearance within multicellular shaped organisms of a diversity of differentiated cells (Fig. 13 .1 ). Internally and externally, cells increased the complexity of their compartments, and even new oxygen-utilising organelles, mitochondria, were incorporated. Later, within multicellular differentiated systems, similar cells came together to form interactive large organs. Continuously, the survival of complicated species increased, but these higher organisms also became increasingly reliant on lower organisms thus generating ecosystems of co-operative biological chemistry.
Man’s selection of the chemical elements
Authors: Williams R J P , Da Silva J J R Frausto
Published: November 2023

Before we begin to look at the remarkable changes in the natural selection of the chemical elements brought about by man we need to see the purpose of his activity, which is largely feeding, protection and comfort, which includes pleasure. Man is a relatively long-living animal of about 100 years lifespan. Once he had become sufficiently successful as a reproducing species (genotypic isolation through strong internal protection) expanding over the Earth to a considerable degree, his survival strength evolved rapidly through phenotypic protection (Table 14.1). Protection in biological systems involves the internal chemical systems and external physical and chemical armoury, but clearly the internal systems are not readily altered, although man has begun to approach such alterations (Section 14.8). It need not be thought that any special development, for example self-conscious reflection, that man possesses was required to start him building up many external forms of phenotypic protection any more than that these were required for initial basic internal protection-both protection forms exist in lower animal species. Thus, the internal immune system has a long evolution in even lower animals and parallel protection exists in plants. As far as external protection is concerned, where genotypic expression and phenotypic development may become confused, it is enough to remember that some molluscs live in rock holes, silk worms build cocoons, and termites, birds and fish produce mud houses and mould clays with straw (nests), to give just a few examples. Furthermore, a central feature of the internal and external systems of advanced animals is group communication, which strengthens their organisation and hence protection.
The evolving natural selection of the chemical elements and the senses
Authors: Williams R J P , Da Silva J J R Frausto
Published: November 2023

In this book we have analysed the natural selection of the chemical elements in the three physical states of matter and in particular chemical combinations in an effort to understand all the material objects we see around us. By natural selection we mean selection based upon different driving influences, all ultimately due to atomic structure, which fall under four headings: Selection through the equilibrium distribution of atoms between given states of matter and in chemical combinations, that is, due to the maximum affinities between elements and generated combinations of elements in molecules and in other assemblies (see Table 16.1 and Chapters 2-6 and 8).
Carboxy group modifications𠄔 synthesis of a homochiral ketone derived from L-tryptophan
Authors: Merchant Kevin j.
Published: November 2023

In 119311 von Euler and Gaddum11 isolated a chemical from equine brain extracts which they called 𠄘substance P𠄙. Substance P was subsequently discovered to be a short peptide2with the sequence Arg-Pro-Lys-Pro-Gln-GlnPhe-Phe-Gly-Leu-Met-NH2. Substance P has been implicated in a variety of disease states including rheumatoid arthritis3, migraine headaches4 and asthma5 and is also associated with the transmission of pain signals.6 A substance P antagonist might therefore be of great therapeutic value. The tryptophan-derived ketone (Scheme 7.11) developed from a screening lead in our laboratories has been shown to be a potent substance P antagonist.𠄙 To provide material for extensive structure activity studies a reliable route to multi-gram quantities of the active S enantiomer of the parent amino ketone had to be developed. In this chapter the evolution of the synthetic strategy and full practical details of the route developed will be discussed.
Benzophenone Schiff bases of a-amino acid esters as electrophiles. Addition of Grignard reagents and alkyllithiums to produce threo-amino alcohols and amino polyols
Authors: Polt Robin l.
Published: November 2023

Since their introduction by M. J. O𠄙Donnell in the late 11970s, benzophenone Schiff bases have become increasingly useful as chiral intermediates for the enantioselective synthesis of unnatural amino acids. These sterically hindered Schiff bases (O𠄙Donnell𠄙s Schiff bases) are particularly convenient because of their good thermal stability, enhanced tolerance of moisture, stability during chromatography over silica gel, and their tendency to crystallize. As a protecting group, the benzophenone Schiff base is extremely versatile. The imine bond can be hydrolysed by use of a variety of acidic conditions, hydrogeno lysed at atmospheric pressures with Pd-C as catalyst, or may be reduced with metal hydrides (cf. LiAlH4, NaBH4 or NaH3BCN) to provide N-benzhydryl protected amines. (cf. Fig. 9.11) All these cleavage reactions proceed in excellent yield.
Perturbation Theory Of Intermolecular Forces At Long Range
Authors: Stone A J
Published: November 2023

Because intermolecular forces are relatively weak, it is natural to describe them using perturbation theory. If the molecules are far enough apart that the overlap between their wavefunctions can be ignored, the theory becomes relatively simple, so we will study this case first. It was first treated by London (1930a, 1937), and has been re-formulated by others since then (Margenau 1939, Longuet-Higgins 1956, Buckingham 1967).
Linear dichroism of small molecules
Authors: Rodger Alison , Norden Bengt
Published: November 2023

LD spectra are quickly measured and usually easy to interpret. However, not many research groups use LD because the equipment required for orienting samples is not currently commercially available. An aim in this book is to show that establishing LD facilities is fairly straightforward and that the effort is well recompensed by the data that can be collected.
Analysis of circular dichroism: magnetic dipole allowed transitions and magnetic CD
Authors: Rodger Alison , Norden Bengt
Published: November 2023

Most of this chapter is devoted to the CD of magnetic dipole allowed (mda)/ electric dipole forbidden (edf) transitions. In the final section we shall also briefly examine the CD induced into electric dipole allowed (eda)/magnetic dipole forbidden (mdf) transitions by a permanent magnetic field: the so-called magnetic CD or MCD. The mechanisms giving rise to the CD of mda transitions and to MCD are quite different, but they naturally fit together since, in addition to their similar titles, both techniques often enable transitions whose existence is undetected or merely suspected in a normal absorption spectrum to be identified.
Circular dichroism formalism
Authors: Rodger Alison , Norden Bengt
Published: November 2023

This chapter is designed to enable readers to understand the basis of the equations used in previous chapters and to enable the CD theory literature to be read. Much of the interpretation of the final equations has already been covered in the previous chapters. This chapter therefore has very few pictures, comparatively little discussion, but many equations.
Crystallographic Instrumentation
Authors: Aslanov L A , Fetisov G V
Published: November 2023

Innovations in crystallographic instrumentation and the rapid development of methods of diffraction measurement have led to a vast improvement in our ability to determine crystal and molecular structure. This up-to-date resource will allow the reader to harness the potential of X-ray diffraction instruments. Different sources of X-radiation used in crystallography are introduced, including synchrotron radiation, as well as a systematic review of detectors for X-rays and basic instruments for single crystal and powder diffractometry. The principles of the diffraction experiment are discussed and related to their practical application with a comparative description of different scan procedures. Diffraction data collection and processing are also reviewed and methods for error correction are described. This book will provide a useful guide for researchers and students starting in this area of science, as well as skilled crystallographers.
Odour sensors
Authors: Gardner Julian W , Bartlett Philip N
Published: November 2023

is clear that the types of sensors which can be used in an electronic nose need to be ones which are responsive to molecules in the gas phase. Many different types of gas sensor are available and many of these have been used in electronic noses at one time or another. However, at present, commercial instruments are concentrated on two main types of gas sensor-metal—oxide and conducting polymer resistive sensors—with more recent work beginning to exploit other types. In this chapter we will describe the basic operational principles behind the most common types of gas sensor and discuss their suitability for application in electronic noses. We begin by considering the general requirements of any gas sensor for use in an electronic nose.

As we have seen in Chapter 3, odorous molecules are typically volatile organic molecules with relative molar masses in the range 30 to 300 dalton. Further, as we saw, the structure of the molecule is important in determining the odour. Thus we require sensors which are non-specific yet which are responsive to the shapes or structural features of the organic molecules. Ideally, we would be able to define what these structural features were and so select, or design, our sensors accordingly. Unfortunately, our understanding of the mammalian olfactory system and the nature of the olfactory receptor proteins is, as yet, insufficiently advanced for this to be a practical prospect. Thus, at present, a more empirical approach is necessary, making use of available sensor types and attempting to modify sensor designs to meet the requirements of the electronic nose.
The diversity of shore organisms
Authors: Little Colin , Williams Gray A , Trowbridge Cynthia D
Published: November 2023

Life almost certainly evolved in the sea, and one of the legacies of this origin is the extraordinary diversity of life forms still found there. Thus there are still something over 30 different animal phyla in marine ecosys-tems, in comparison with only a third of this number on land. Admittedly, not all the marine phyla are common on rocky shores—some are con-Ined to the deep sea, some are primarily pelagic, and some prefer soft sediments—but at least 10 of them are regular components, large enough and common enough to be seen by visitors to the shore.

Estimates for numbers of species in the sea as a whole range from an unlikely low of 200,000 species to an unlikely high of 10 million (Rohde, 2002), and we know very little about the factors that control the variety and numbers of species on the shore. Marine biodiversity may, however, relate to ecosystem function—and especially to the interactions between consumers and producers (Solan et al., 2006).
Coping with life on the shore: adaptations of littoral organisms
Authors: Little Colin , Williams Gray A , Trowbridge Cynthia D
Published: November 2023

Rocky shores are not easy places in which to live. The rising and falling tides produce conditions that alternate between submersion in seawater and emersion into a rigorous drying atmosphere. At the same time, variations in wave action can make the settling of larvae and the attachment of adult forms a real trial of strength. In spite of these problems, however, immense numbers of primary producers, grazers, suspension feeders, and predators make rocky shores their home. They reproduce in a variety of ways, their life cycles encompass a complex mosaic of styles, and they have adaptations that allow them to withstand most of the physical stresses of life on the shore. But just how well do these adaptations work?
Migraine With and Without Allodynia: New Sub-Classification of Migraine
Authors: Burstein R , Jakubowski M
Published: November 2023

We have recently shown using quantitative sensory testing technique, that migraine headache may be associated with high incidence (about 75%) of ipsilateral cutaneous allodynia, particularly in periorbital and temporal skin areas, and proposed that this is the very reason why patients feel that during migraine, their skin hurts in response to otherwise innocuous activities such as combing hair or wearing it in a pony tail, shaving, taking a shower, brushing their upper teeth, wearing glasses or earrings, or resting their head on the migraine side.
Headache Attributed to Trauma
Authors: Láinez M J A
Published: November 2023

Posttraumatic Headache (PTH) is one of the several symptoms of the postconcussive syndrome, usually the most frequent, and it may be accompanied by additional cognitive, behavioral, or somatic problems (Solomon 2001). Headache can start after brain, head, or neck injury and simulate the clinical characteristics of several primary headaches. Usually PTH is self-limited. Severe, moderate, and mild head injuries have been related to the beginning of new headaches.
Discussion Summary, the Secondary Headaches: Part I
Authors: Goadsby P J
Published: November 2023

The Secondary Headaches discussed in this poster session were those attributed to infection, vascular disorders, substance use, and trauma. Headache associated with dissections of arteries of the neck were discussed. A poster on spontaneous dissections of the carotid and vertebral arteries were noted to be associated with neck pain, cervicalgia, in 45% of patients presenting to a stroke unit (Lucas). These dissections were diagnosed using MRI.
Algorithms and Simplified Approaches to Headache Diagnosis
Authors: Lipton R B , Bigal M E
Published: November 2023

Migraine remains a substantially under-diagnosed and under-treated condition. Prior reports have divided barriers to migraine diagnosis and treatment as follows: 1. Under-recognition of migraine by headache sufferers themselves; 2. Under- consultation among migraine sufferers who need medical care; 3. Failure to diagnose all who consult; 4. Failure to initiate appropriate therapy among all who are diagnosed; 5. Lack of on-going assessment of the benefits of treatment. Screening tools and simplified approaches to headache diagnosis may help address these barriers to care.
The FRAMIG III Survey: First Epidemiological Survey in General Population According to the 2004 IHS Migraine Criteria
Authors: Lucas C , Lanteri-Minet M , Chautard M H
Published: November 2023

In 1990, the first nationwide survey of migraine using the International Headache Society (IHS) criteria for the diagnosis of migraine was conducted in France on a representative sample of residents aged 15 years and more. Headache sufferers were classified as IHS migraine, ‘borderline’ migraine, possible migraine, and non- migrainous headache. The study found an overall prevalence of HIS-migraine of 8.1%; another 4% of patients being classified as ‘borderline’ migraine, which we in fact considered as definite migraine.
The structure of ICPC
Authors:   Wonca
Published: November 2023

ICPC is based on a simple bi-axial structure: 17 chapters based on body systems on one axis, each with an alpha code, and seven identical components with rubrics bearing a two-digit numeric code as the second axis (Fig. 1 and Table 2). ICPC has a significant mnemonic quality which facilitates its day-to-day use by physicians, and simplifies the centralized manual coding of data recorded elsewhere.
Horizontal and intracellular gene transfer in the Apicomplexa: The scope and fnctional consequences
Authors: Huang Jinling , Kissinger Jessica C
Published: November 2023

The availability of completed genomes from diverse Apicomplexa, including the genera Plasmodium, Theileria, Toxoplasma, and Cryptosporidium, facilitates comparisons of the phylogenetic history of all genes encoded in these genomes. Surprisingly, genealogical analyses indicate that in numerous cases, metabolic genes in the Apicomplexa have been acquired by intracellular and lateral gene transfer. These acquired genes have provided the parasites with unexpected metabolic activities that have facilitated their evolution and pathogenesis. In some cases, these acquired genes may serve as therapeutic targets since they represent essential activities that are present in the parasite but not in the hosts they infect.