bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscle
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter explains that muscles, a tissue consisting of contractile cells, are specialised for movement. All animals use muscles to generate movements that accomplish behaviours and to accomplish psychological functions. The chapter considers the physiological and biochemical mechanisms that underlie muscle contraction, and then the adaptations of certain muscles specialised to perform different functions. Excitation-contraction coupling is the relationship between depolarisation and contraction, which correlates to how neural excitation triggers skeletal muscle contraction. The chapter also details the properties and functions of vertebrate smooth muscles and cardiac muscles, which contrasts with skeletal muscles that contract only when stimulated by motor neurons.
Transport of Solutes and Water
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter focuses on the transport of solutes and water. It defines transport as any and all movements of solutes or water across cell membranes or epithelia regardless of its mechanisms. Passive-transport mechanisms, by definition, are capable of carrying material only in the direction of equilibrium. Meanwhile, active-transport mechanisms, by contrast, can carry material in the direction opposing equilibrium. The chapter also elaborates on the concept of simple diffusion and facilitated diffusion. It also discusses the diversity and modulation of channels and transporters. It also looks at the process of osmosis, which is the passive transport of water across a membrane.
Energy Metabolism
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter discusses energy metabolism. It defines energy metabolism as the sum of the processes by which animals acquire energy, channel energy into useful functions, and dissipate energy from their bodies. Energy metabolism consists of two subsets: catabolic processes and anabolic processes. Animals utilise their absorbed chemical energy for biosynthesis, maintenance, and generation of external work. The chapter then correlates the second law of thermodynamics to the reason why animals require energy. It discusses metabolic rate as the rate at which an animal consumes energy before detailing the factors that affect metabolic rates, such as gender and time of day.
Introduction to Oxygen and Carbon Dioxide Physiology
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter introduces oxygen and carbon dioxide physiology. It starts with the properties of gases in gas mixtures and aqueous solutions. The respiratory gases move from place to place principally through the mechanisms of simple diffusion and convection (bulk flow). Simple diffusion is one of the two principal mechanisms of respiratory gas transport, while transport by bulk flow occurs when a gas mixture or an aqueous solution flows and gas molecules in the gas or liquid are carried from place to place by the fluid flow. Additionally, the concept of chemical potential plays a significant role in understanding respiratory gases and gas transport. The chapter also considers the concept of oxygen cascade in line with understanding the transport of O2 from the environment to the mitochondria of an animal.
Circulation
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter tackles the relevancy of circulation in all kinds of animals. The concept of circulation expanded to include the transport of these agents from one region of the body to another after the discovery of hormones, antibodies, and immune cells. Moreover, Circulatory systems are classified as open or closed, depending on whether the entire circulatory path is enclosed in discrete vessels. The chapter highlights the importance of the heart working as a pump in the process of circulation and the principles of pressure, resistance, and flow in vascular systems. It details the features and process of circulation in mammals, birds, fish, and invertebrates.
A Brief Introduction to the Bilateria and Its Major Clades
Authors: Brusca Richard C. , Giribet Gonzalo , Moore Wendy
Published: September 2023

This chapter introduces the Bilateria and its major clades. It describes how the phyla within Bilateria changed following the emergence of molecular phylogenetics in the 1990s. Several long-standing groups, such as Protostomia and Deuterostomia, have changed their phylum memberships, and a number of new higher-level clades have emerged. Essentially, the Bilateria is a clade of animals whose adult tissues are derived from three embryonic germ layers and whose body axis is anteroposterior. Deuterostomia includes only three phyla, (Chordata, Hemichordata, and Echinodermata), while Protosomia is a monophyletic lineage containing the two large clades, Spiralia and Ecdysozoa. The chapter also considers the recently discovered phyla, such as Xenacoelomorpha and Nephrozoa.
Phylum Xenacoelomorpha
Authors: Brusca Richard C. , Giribet Gonzalo , Moore Wendy
Published: September 2023

This chapter notes the characteristics of the phylum Xenacoelomorpha. It explains that the evolution of bilaterality resulted in cephalization with the exception of Xenacoelomorpha, wherein bilaterians further evolved a complete gut with a mouth and an anus, and excretory organs in the form of protonephridia and metanephridia. Phylogenetic research strongly suggests that the Xenacoelomorpha split early from the remaining bilaterian lineage. The phylum Xenacoelomorpha comprises three clades of acoelomate worms: Acoela, Nemertodermatida, and Xenoturbellida. The chapter mentions how important areas of future research for xenacoelomorphs are related to their phylogenetic position, evo-devo studies of regeneration and body patterning, and a better understanding of development.
Phylum Nemertea
Authors: Brusca Richard C. , Giribet Gonzalo , Moore Wendy
Published: September 2023

This chapter looks into the members of the phylum Nemertea that are commonly known as ribbon worms. The unsegmented vermiform animals are usually flattened dorsoventrally and are moderately cephalized while also possessing highly extensible bodies and strong regeneration powers. Many features of the nemertean body plan are similar to the conditions seen in flatworms. Of all the animal phyla, nemerteans are unique in presenting a compact body and protonephridial excretory system, which is similar to flatworms, while possessing coeloms. The chapter then discusses the taxonomic history and classification of ribbon worms, which are subdivided into two main clades, Palaeonemertea and Neonemertea.
Living in Water
Authors: Harvey Pough F. , Bemis William E. , Mcguire Betty , Janis Christine M.
Published: September 2023

This chapter looks at vertebrates which live successfully in water. A vertebrate must adjust its buoyancy to remain at a specific depth and must force its way through a dense medium to pursue prey or escape predators. Thus, aquatic vertebrates have evolved solutions to the physical challenges of life in water. The chapter primarily focuses on fishes and lissamphibians to consider sensory systems in water and on land. The evolutionary diversification of teleosts resulted in an enormous array of sizes and ways of life in freshwater and marine environments. The chapter details the process of osmoregulation in different environments.
Synapsids and Sauropsids
Authors: Harvey Pough F. , Bemis William E. , Mcguire Betty , Janis Christine M.
Published: September 2023

This chapter covers two ways of living on land with reference to synapsids and sauropsids. The mammalian lineage is characterized by synapsid skulls that have a single fenestra, while members of the reptilian lineages have diapsid skulls with two fenestrae. Skull structure is only one way in which the evolutionary histories of Synapsida and Sauropsida diverged, as members of both lineages adapted to the challenges of life on land. The chapter explains the cardiovascular systems and excretory systems of synapsids and sauropsids. It highlights how their differences in structural and functional characters showcase that there is more than one way to succeed as a terrestrial amniote.
The Value of Biodiversity
Authors: Sher Anna A.
Published: September 2023

This chapter examines the value of biodiversity, considering how ecological economics is developing methods for valuing biodiversity and, in the process, providing arguments for its protection. Benefits humans derive from nature are called ecosystem services, which can be described and quantified in terms of their use value. Direct use values are assigned to products harvested from the wild. Indirect use values can be assigned to aspects of biodiversity that provide economic benefits to people but are not harvested during their use. Meanwhile, the option value of biodiversity is its potential to provide future benefits to human society, such as new medicines, industrial products, and crops. Biodiversity also has existence value, which is the amount of money people and their governments are willing to pay to protect species and ecosystems without any plans for their direct or indirect use. The chapter then looks at the concept of environmental ethics.
The Genetics of Axis Specification in Drosophila
Authors: Barresi Michael J. F. , Gilbert Scott F.
Published: September 2023

This chapter considers drosophila cleavage as superficial as the nuclei divide thirteen times before being compartmentalized and reside in a syncytial blastoderm before cell formation. It details how the drosophila embryo undergoes a mid-blastula transition, wherein the cleavages become asynchronous and new mRNA is made. It also talks about gradients of morphogens which determine the specification of different cell types. The chapter looks at the gap gene proteins that activate and repress the pair-rule genes, which have modular enhancers that become activated in seven “stripes.” It analyzes how organs form at the intersection of dorsal-ventral and anterior-posterior regions of gene expression.
Brain Growth
Authors: Barresi Michael J. F. , Gilbert Scott F.
Published: September 2023

This chapter discusses the radial glial cells that serve as the neural stem cells in the embryonic and fetal brain. It examines the neurons of the brain and shows how they are organized into laminae (layers) and nuclei (clusters). It also details how new neurons are formed by the division of neural stem cells in the wall of the neural tube. They then migrate away from the ventricular zone and form a new layer, called the mantle zone. The chapter points out the difference between human brains and those of other primates, in terms of elements such as the retention of the fetal neuronal growth rate during early childhood, the altered transcriptional activity of certain genes, and the presence of human-specific alleles of developmental regulatory genes. It explores the number and complexity of gyri and sulci folds of the neocortex that are correlated with the level of intelligence.
Evolution and Ecology
Authors: Bowman William D. , Hacker Sally D.
Published: September 2023

Key Concepts

CONCEPT 6.1 Evolution can be viewed as genetic change over time or as a process of descent with modification.

CONCEPT 6.2 Natural selection, genetic drift, and gene flow can cause allele frequencies in a population to change over time.

CONCEPT 6.3 Natural...
Plant and Cell Architecture
Authors: Taiz Lincoln , Møller Ian Max , Murphy Angus , Zeiger Eduardo
Published: September 2023

This chapter provides an overview of the basic anatomy and cell biology of plants, from the macroscopic structure of organs and tissues to the microscopic ultrastructure of cellular organelles. It shows how plants carry out similar physiological and biochemical processes, despite their great diversity in form and size. It also considers land plants as sessile organisms that convert solar energy to chemical energy, use growth instead of motility to obtain resources, and have vascular systems, rigid structures, and mechanisms to avoid desiccation on land. The chapter discusses plants and green algae, which are the ultimate solar energy collectors as they harvest the energy of sunlight by converting light energy to chemical energy. It points out how plants are structurally reinforced to support their mass as they grow toward sunlight against the pull of gravity.
Signals and Signal Transduction
Authors: Taiz Lincoln , Møller Ian Max , Murphy Angus , Zeiger Eduardo
Published: September 2023

This chapter provides a brief overview of the types of external cues that direct plant growth and discusses how plants employ signal transduction pathways to regulate gene expression and posttranslational responses. It highlights the surprising discovery that, in the majority of cases, plant signal transduction pathways function by inactivating, degrading, or relocating repressor proteins that modulate transcription. It also explains the requirement of signal amplification via second messengers and mechanisms for signal transmission to coordinate responses throughout the plant. The chapter demonstrates how individual stimulus-response cascades are often integrated with other signaling pathways to shape plant responses to their environment in time and space. It mentions plant signal transduction mechanisms that may be relatively rapid or extremely slow.
Water Balance of Plants
Authors: Taiz Lincoln , Møller Ian Max , Murphy Angus , Zeiger Eduardo
Published: September 2023

This chapter examines the mechanisms and driving forces operating on water transport within the plant and between the plant and its environment. It begins the discussion about water transport by focusing on water in the soil. It also describes how water moves from the soil into the roots and from the roots up through specialized transport cells to the leaves, from which water is lost to the atmosphere. The chapter considers the ways in which the leaf can control the loss of water, as well as the entry of CO2, by regulating the opening and closing of stomata, the small openings through which CO2 uptake and the majority of water loss occur. It illustrates physical forces that drive the movement of water from soil to plant to atmosphere without the involvement of any metabolic pump.
Solute Transport
Authors: Taiz Lincoln , Møller Ian Max , Murphy Angus , Zeiger Eduardo
Published: September 2023

This chapter considers the physical and chemical principles that govern the movement of molecules in solution and shows how these principles apply to membranes and biological systems. It discusses the molecular mechanisms of transport in living cells and the great variety of membrane transport proteins that are responsible for the particular transport properties of plant cells. It also explores the channels, transporters, and pumps of stomatal guard cells and their roles in signal transduction and in the control of osmotic gradients that drive changes in stomatal aperture. The chapter looks at the pathways that ions take when they enter the root and the mechanism of xylem loading, which is the process whereby ions are released into the tracheary elements of the stele. It explains solute transport in plants that can contribute solutions to sustainable food production as transported substances are vital for human nutrition.
Vegetative Growth and Organogenesis: Branching and Secondary Growth
Authors: Taiz Lincoln , Møller Ian Max , Murphy Angus , Zeiger Eduardo
Published: September 2023

This chapter surveys vegetative growth by examining the mechanism of branching and secondary growth. It highlights developmental pathways on the branches of shoots and roots and shows how these originate from different structures but converge on a common endpoint, which is the production of new apical meristems which greatly enhances the rate of increase in plant biomass. It also points out the developmental pathways that share key similarities in their hormonal responses and genetic control mechanisms. The chapter describes vegetative growth and some of its regulatory pathways that underly the production of secondary xylem and phloem. It examines secondary growth which allows further increases in plant biomass by greatly extending the limits on height.
Blockade of angiotensin-II receptors
Authors: Saunders John
Published: September 2023

This chapter takes a closer look at losartan and valsartan which are used in reducing blood pressure. It gives a brief overview of the factors leading to the synthesis of losartan. Then it describes the two key components required for the convergent route leading to losartan: the preformed imidazole and a substituted biphenyl derivative. The chapter presents the pathways by which losartan has been prepared. It also reviews the synthesis of valsartan, which was first approved in 1996. The process involves the hydrolysis to the primary alcohol via acetate, Swern oxidation, amination with L-valine methyl ester, and acylation with valeric acid chloride, among others.
Proton pump inhibitors as gastric acid secretion inhibitors
Authors: Saunders John
Published: September 2023

This chapter tackles omeprazole which had been characterized as a gastric acid-pump inhibitor, blocking the final step of acid production and thus curbing acid production by all stimulatory mechanisms. The chapter first explains the omeprazole cycle, noting that the omeprazole’s mechanism of action is not entirely straightforward and is dependent on a subtle balance of chemical reactivity, controlled by the nature of substituents in the pyridine ring, and enzymatic transformation under the physiological conditions prevailing in the gut and liver. The chapter then explains the process by which omeprazole was made. It also looks at lansoprazole, a close analogue of omeprazole.
Hypnotic, anxiolytic anticonvulsant and muscle relaxant agents acting at the benzodiazepine receptor
Authors: Saunders John
Published: September 2023

This chapter looks at benzodiazepines, which are used as hypnotics, anxiolytics, anticonvulsants, and muscle relaxants. It tackles the importance of the discovery of ligands acting at benzodiazepine receptors and highlights that the benzodiazepines exert their pharmacological effects by interaction at a specific site on the GABAA receptor complex. The chapter describes how diazepam was made, noting that lorazepam and temazepam also follow similar routes. It also discusses a newer approach for the synthesis of diazepam. The chapter then tackles some routes in producing alprazolam. Furthermore, it describes the synthesis of flumazenil-emphasizing that the earlier work with diazepam using isatoic anhydride as a starting material provided the route development for flumazenil. Lastly, it describes the features of zolpidem, a non-benzodiazepine hypnotic which binds at the same site of the ? subunit of the GABA receptor complex as classical benzodiazepines.
Introduction
Authors: McCleverty Jon
Published: September 2023

This chapter discusses transition elements. These are defined strictly as those elements that have partly filled d or f shells. It focuses on the first-transition elements and determines which elements should be considered as transition elements that separate the first-row from the second-, third-, and fourth-row congeners. It also examines the main reasons for considering the first-row transition elements apart from their heavier congeners, such as the simplicity of the aqueous chemistry of the first-row elements and the use of crystal field theories in explaining many of the physical and chemical properties of compounds. The chapter defines the relative stability of oxidation states for a particular metal ion by including the ionization enthalpies of the metal and ionic radius of the ion. It looks at detectable trends in oxidation state stability for the first-row transition elements.
Time
Authors: Green N. J. B.
Published: September 2023

This chapter explores the position of time. In Schrödinger theory, time is treated as a parameter that can be used to follow the evolution of an event. The chapter reviews the theory of relativity wherein time becomes a fourth spatial dimension and considers a linear transformation of a coordinate system in four-dimensional space-time that changes the frame of reference. It also looks at classical mechanics which provide an accurate description of macroscopic systems wherein speed approaches the magnitude of the speed of light. The chapter analyses Schrödinger time-dependent theory, which provides an accurate description of transient phenomena on the microscopic scale as long as speed remains small. It talks about the best way of deriving the time-dependent Schrödinger equation through the relativistic Dirac theory, which has the virtue of introducing both time and spin in a proper way.
General properties
Authors: Chipperfield John R.
Published: September 2023

This chapter focuses on the importance of non-aqueous liquids in living systems, and states that water is considered the most abundant liquid on earth. It examines the range of liquid solvents available and discusses how the choice of solvents is related to the various solvent properties. It also explains that solvents are used to bring reactants together at suitable concentrations, such as endothermic reactions wherein heat can be supplied readily by heating the solvent and exothermic reactions wherein the solvent can act as a heat sink. The chapter discusses how solvents frequently react with solutes and how solutions offer a convenient way of delivering chemical compounds to their point of use. It outlines the multiple types of solvent that act as a solvent to different solutes.
Chemistry in non-aqueous solvents
Authors: Chipperfield John R.
Published: September 2023

This chapter explains how non-aqueous solvents are used as media for carrying out reactions and as carriers to deliver solutes to their point of use. It looks at the various classes of reaction in which the solvent can participate, such as acid-base reactions that can take place in the gas phase. It also talks about the acid-base reactions in water, which have been extensively studied to provide an insight into the nature of acidity. The chapter discusses acid as a substance that either alone or through reaction with the solvent gives the caution formed in the self-ionization of the solvent. It mentions solvents, such as hexane, acetone, acetonitrile, DMSO, and liquid sulfur dioxide, which do not self-ionize.
Some molecular solvents
Authors: Chipperfield John R.
Published: September 2023

This chapter looks at the chemistry of a number of electrolytic molecular solvents and discusses supercritical fluids. These share many of the properties of molecular liquids. It mentions acetic acid, which has a liquid range that is similar to water and boils at the same temperature as similarly sized molecules. It also describes acetonitrile as a popular dipolar solvent that combines several desirable characteristics, such as having a dielectric constant that places it towards the lower polarity end of electrolytic solvents. The chapter refers to the solubilities in liquid ammonia that favour non-polar molecular compounds and inorganic compounds where ammine formation can take place. It discusses dinitrogen tetroxide, which is a useful solvent for investigating nitrations.
Molten framework solids
Authors: Chipperfield John R.
Published: September 2023

This chapter traces the long history of molten framework solids’ use as solvents, such as in glass making, a practice dating back to ancient times, and which uses molten silicon dioxide and calcium oxide. It mentions molten salts which have been used as electrolytes since 1807 when Sir Humphry Davy first isolated metals from their molten hydroxides using electrolysis. It also looks at the definitions of acids and bases which are useful in rationalizing chemistry in terms of the breakdown of molecular solvents when considering molten framework solids. The chapter points out that calcium oxides react with silicon dioxide at high temperatures to give calcium silicate. It highlights the reaction of sodium fluoride with aluminium fluoride to give cryolite, which can be thought of as a Lewis acid-base reaction.
Protecting Group Chemistry
Authors: Robertson Jeremy
Published: September 2023

Protecting Group Chemistry provides an overview of the general methods that are used to block the reactivity ofi.e. protectspecific functional groups, thus allowing others, present within the same molecule, to be manipulated unambiguously. An introductory chapter outlines protecting group strategy, relevant aspects of functional group reactivity, temporary protection, and introduces the concept of protecting group devices as an aid to unifying the wide range of available methods. The rest of the book is divided on the basis of broad classes of the experimental conditions that lead to cleavage of each protecting group (acid/electrophile, base/nucleophile, oxidising or reducing agent).
The Earth and biogeochemical cycling
Authors: Howard Alan G.
Published: September 2023

This chapter begins by describing the structure of the Earth. Current understanding of the composition of material at the centre of the Earth is restricted to that which can be inferred from indirect physical measurements. The outermost layer of the solid Earth—its crust—is the most familiar to man and is the part of the Earth most intimately associated with the aquatic environment. Below the crust is the mantle, and at the centre of the Earth is its core. In describing the chemistry of the aquatic environment, it will be necessary to draw upon terms originating from fields such as biology, geology, and hydrology. The chapter lists some of the most commonly encountered terms. It then looks at the geochemical cycles.
Adsorption and desorption
Authors: McCash Elaine M.
Published: September 2023

This chapter examines adsorption and desorption. There are several possible outcomes when an atom or a molecule hits a surface, including elastic and inelastic scattering. However, the outcome of an atomic or a molecular collision that results in the retention of the molecule on the surface is of far greater importance to the study of surface chemistry. There are two types of interactions that can occur: physical adsorption (or physisorption) and chemisorption. In each case, the atom or molecule being adsorbed on the surface is usually described as the adsorbate; the adsorbing surface is usually termed the adsorbent or substrate. The chapter then looks at adsorption isotherms, before considering the measurement of heats of adsorption, isosteres, and desorption rates. It also discusses adsorption sites and geometries. Finally, the chapter highlights two methods which can provide information on surface chemical composition: auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS).
Ultrathin films and interfaces
Authors: McCash Elaine M.
Published: September 2023

This chapter assesses ultrathin films and the interfaces between two different materials. In this case, the adsorbate–adsorbate interactions are often just as or even more important than the substrate–adsorbate interactions. The driving force behind work in this area is the application of surface science in the microelectronics industry. In recent years, it has been found that if a complete layer of one material is grown on another, the competition between adsorbate–adsorbate interaction and substrate–adsorbate interaction leads to some very interesting properties for the overlayer film that are quite different to those observed for the bulk material. These different properties can be electronic, structural, chemical, and/or magnetic and may be significant in terms of catalysis.
Waves and vibrations
Authors: Ritchie G.A.D. , Sivia D.S.
Published: September 2023

This chapter defines periodic motion as an action that is repeated at regular intervals. This is one of the most common forms of mechanical behaviour. Examples of this are vibrational modes of molecules and the wave-like properties of electromagnetic radiation, including simple harmonic motion (SHM). SHM, discussed in detail in this chapter, best illustrates oscillatory characteristics and is frequently used as an idealized model to analyse real-life situations. The chapter explores the important role resonance plays in science, elaborating the physical basis of absorption lines in the infra-red spectrum of a molecule. It talks about the vibrational modes of molecules and explains that they can be understood in terms of the behaviour of a collection of point-masses joined together by springs.
Electrostatics
Authors: Ritchie G.A.D. , Sivia D.S.
Published: September 2023

This chapter introduces charge as the fundamental property of positive or negative electrons and protons, citing experiments wherein like charges repel while opposite charges attract. It examines the electrostatic interactions that are responsible for the existence of molecules and their chemical and thermodynamic properties. It also discusses the simplest electrostatic reaction between two isolated charged particles that have negligible sizes compared to their separation. The chapter recounts how Charles-Augustin de Coulomb showed experimentally that the magnitude of force between two charged particles is proportional to the product of their charges and to the square of their separation. It clarifies that force is a vector that is collinear with the internuclear separation.
Programming the hardware
Authors: Pete Biggs
Published: September 2023

This chapter discusses the techniques used to control and present the data on the interface hardware. It talks about the reading and writing memory locations which modify the data held in the registers. It also highlights how the action of reading data from an analogue to digital converter (ADC) might start the next conversion, while a different type of ADC may require the register to be toggled and to initiate the conversion sequence. The chapter cites Microsoft Windows as a multitasking system which requires programs to be well-behaved and to regularly relinquish control of the machine to other programs. It reviews the abilities of various high-level languages in relation to interfacing and machine-level programming.
Atoms and ions: the building blocks of matter
Authors: Lawrence Nathan , Wadhawan Jay , Compton Richard
Published: September 2023

This chapter presents questions and answers on various topics that are central to the study of chemistry, which include the atomic size, Avogadro constant, and the Pauli exclusion principle. The chapter illustrates the structure of the hydrogen atom and its electronic spectrum, as well as many-electron atoms. It also includes worked examples that demand a solution on how many nearest neighbours there are to any atom in the face-centred cubic (fcc) and hexagonal close packed (hcp) structures and the volume occupied in the body-centred cubic (bcc) structure. The chapter mentions low-energy electron diffraction (LEED), which can be used to study the structure of solid surfaces. It discusses the effective diffraction of the incident beam of electrons, which is obtained if the wavelength of the electrons is similar to the interatomic spacing.
Chemical equilibria
Authors: Lawrence Nathan , Wadhawan Jay , Compton Richard
Published: September 2023

This chapter gives a range of problems that explain the Le Chatelier's principle and equilibrium constants and chemical speciation in both gases and solutions. It describes the relationship between the standard Gibbs free energy changes of a reaction and the equilibrium constant for the reaction. It also covers acid-based equilibria, complex-ion formation, solubility of solids, and redox equilibria. The chapter shows the phase diagrams of water and carbon dioxide and provides a comment on the variation of the phase boundaries with temperature and pressure. It reviews the trends influencing the pressure-temperature behaviour of the melting point, such as the endothermic nature of the melting process wherein the higher temperature encourages the formation of the liquid phase.
Crystal growth
Authors: Davey Roger J. , Garside John
Published: September 2023

This chapter examines crystal growth. When a crystal surface is exposed to a supersaturated environment, the flux of growth units (atoms, ions, molecules) to the surface exceeds the equilibrium flux so that the number of growth units joining the surface is greater than that leaving. This results in growth of the surface. Since the energetics of this process will depend not only on the solid state but also on the supersaturated fluid adjoining it, the chapter then describes crystal–fluid interfaces. It also considers in more detail the possible pathways by which a molecule passes from the solution to become integrated into a lattice position on a growing face. Before growth units can become incorporated into the crystal lattice by one of these mechanisms, however, they must be transported from the bulk of the solution to the crystal–solution interface.
Crystals in formulated products
Authors: Davey Roger J. , Garside John
Published: September 2023

This chapter explores crystals in formulated products. Having developed a process for preparing a product in a crystalline form, it is important to appreciate that these crystals usually then have to be transformed into a product. In some cases, this is achieved by further chemical reaction, in others by formulation. Formulation is a generic term given to the collection of physical processes such as milling, mixing, dissolution, tableting, and melting that transform individual single components into multicomponent products. Perhaps the most important component of a formulated product is the active ingredient which, although isolated in the production plant as a crystalline material with appropriate characteristics for purity and bulk handling, must now be present in a form suitable for maximizing its effectiveness in its end use. The chapter then considers crystals as property controllers, before looking at crystallization controllers.
Entropy and the second law of thermodynamics
Authors: Bowley Roger , Sánchez Mariana
Published: September 2023

This chapter focuses on entropy, which is a function of state for an ideal gas that uses an integrating factor on the inverse of the temperature according to the ideal gas scale. It refers to the use of the second law of thermodynamics to prove that the most efficient engine operating between two heat baths is a Carnot engine. It also discusses the temperature scale that can be defined from the ratio of heat flows in one cycle of the Carnot engine. The chapter defines a thermal reservoir of heat bath as a body that has a huge heat capacity wherein temperature does not change, such as a block of copper that can act as a thermal reservoir for small additions of heat energy. It looks at the simplest expressions of the second law of thermodynamics that relate to a cycle of processes in which heat flows between hot and cold reservoirs that produce work.
Basic concepts
Authors: de Levie Robert
Published: September 2023

This chapter discusses the basic concepts of acids, bases, and pH. The concept of acid and base can be generalized in several ways. The book uses the definition given by Brönsted, which emphasizes the complementary nature of acids and bases in aqueous solutions. It considers as an acid any substance that can donate a proton, and as a base any proton acceptor. In this nomenclature, an acid that loses its proton become a base, and vice versa, so that one can consider conjugate acid-base pairs. Meanwhile, the concept of pH was introduced by Sørensen as the negative logarithm of the hydrogen concentration. The chapter then looks at the mass action law, which is the fundamental law of chemical equilibrium. It also considers concentration fractions, logarithmic concentration diagrams, and the proton condition.
Buffers
Authors: de Levie Robert
Published: September 2023

This chapter focuses on buffers. The previous chapter emphasized the steep change in pH near the equivalence point of a successful titration. The chapter looks at its counterpart: the regions in the titration curve where the pH is responding very little to the addition of a strong acid or base. In many chemical systems, and especially in living cells, maintaining the pH within narrow bounds is essential, because the functioning enzymes (the catalysts of chemical processes in living tissue) depends strongly on pH. The parts of titration curve that vary little as acid or base is added are called the buffer regions, and the corresponding pH-stabilization is called buffer action. The chapter then considers the Henderson approximation.
Introduction
Authors: Davies David T.
Published: September 2023

This introductory chapter provides an overview of heterocyclic chemistry, which is a large and important branch of organic chemistry. Heterocycles occur in nature, for instance in nucleic acids and indole alkaloids. Synthetic heterocycles have widespread uses as herbicides, fungicides, insecticides, dyes, organic conductors, and, of course, pharmaceutical products such as the anti-ulcer drug. Any ring system containing at least one heteroatom can be described as heterocyclic. This broad definition encompasses both aromatic heterocycles and their non-aromatic counterparts. Aromatic heterocycles are described as being heteroaromatic. The chapter then looks at aromaticity and heteroaromaticity, before considering the synthesis of heterocycles. Many classical syntheses of heterocycles revolve around the condensation reaction in its various guises.
Pyridines
Authors: Davies David T.
Published: September 2023

This chapter evaluates pyridine, a polar liquid which is miscible with both organic solvents and water. It can formally be derived from benzene by replacement of a CH group by a nitrogen atom. Pyridine is a highly aromatic heterocycle, but the effect of the heteroatom makes its chemistry quite distinct from that of benzene. The aromatic sextet of six π-electrons is complete without invoking participation of the lone pair on the nitrogen. Hence, the lone pair of pyridine is available for bonding without disturbing the aromaticity of the ring. The effect of the heteroatom is to make the pyridine ring very unreactive to normal electrophilic aromatic substitution. Conversely, pyridines are susceptible to nucleophilic attack. The chapter then considers the synthesis, electrophilic substitution, nucleophilic substitution, and anion chemistry of pyridines.
Six-membered ring heterocycles containing one oxygen atom
Authors: Davies David T.
Published: September 2023

This chapter describes six-membered ring heterocycles containing one oxygen atom. The pyrilium cation, 2-pyrone, 4-pyrone, and their benzo-fused analogues, the benzopyrilium cation, coumarin, and chromone, are the parent structures of a series of six-membered ring heterocycles containing one oxygen atom. The impetus for research in this area comes from the enormous number of plant-derived natural products based on the benzopyrilium, coumarin, and chromone structures. The pyrylium cation is the oxygen analogue of pyridine and is a six π-electron aromatic system. Nevertheless, being a cation, it is reactive towards nucleophiles and is readily hydrolysed to give dialdehyde. In contrast, 2- and 4-pyrones are considered to have relatively little aromatic character. The chapter then looks at the synthesis of a pyrylium salt, a coumarin, and a chromone.
Oxidation of heteroatoms attached to carbon
Authors: Donohoe Timothy J.
Published: September 2023

This chapter discusses the oxidation of heteroatoms attached to carbon. It begins by looking at the oxidation of tertiary amines to give the corresponding N-oxide. The mechanism of this reaction is illustrated by the oxidation of N-methylmorpholine with hydrogen peroxide and involves nucleophilic attack of the amine lone pair of electrons onto the peroxide, breaking the relatively weak oxygen–oxygen bond. Loss of proton then furnishes the amine-N-oxide plus water. A pattern of reactivity similar to that of nitrogen can be observed in the oxidation of phosphorous-containing compounds. However, as phosphorous is lower down the periodic table than nitrogen, it is generally more easily oxidised, as it is more nucleophilic. The chapter then considers the oxidation of sulfur and selenium.
Electrode Potentials
Authors: Compton Richard G , Sanders Giles H W
Published: September 2023

Electrode Potentials provides an introduction to the science of equilibrium electrochemistry, specifically addressing the topics of electrode potentials and their applications. It builds on a knowledge of elementary thermodynamics by giving the reader an appreciation of the origin of electrode potentials, and shows how these are used to deduce a wealth of chemically important information and data such as equilibrium constants; the free energy, enthalpy and entropy changes of chemical reactions; activity coefficients; and the selective sensing of ions. The emphasis throughout is on understanding the foundations of the subject and how it may be used to study problems of chemical interest.
Migration of ions
Authors: Compton Richard G , Sanders Giles H W
Published: September 2023

This chapter covers fully dissociated electrolytes, which are known as strong electrolytes in contrast with weak electrolytes that are largely undissociated in aqueous solution. It refers to the cations which move to the negative electrodes, while anions move towards the positive electrode in the zone of the solution between the electrodes. It also analyses the movement of the ions which constitutes the flow of current in the bulk of the solution. The chapter probes the nature of the current flow at electrode/solution interfaces. It emphasizes that the conductivity is a property of the chemical nature and composition of the electrolyte which implies that the resistance to current flow increases with greater distance between the electrodes and the smaller electrode area.
Going further
Authors: Compton Richard G , Sanders Giles H W
Published: September 2023

This chapter clarifies how to measure standard electrode potentials, for example in obtaining the value of the standard electrode potential of the cell. It recognizes that the potential must be measured under conditions where there are no current flows and requires the use of a digital voltmeter. It also discusses the experimental arrangements involved for the cell of interest, which makes it necessary to produce the hydrogen gas of one atmosphere pressure and the solution unit activity in hydrochloric acid. The chapter looks into the experiments conducted on solutions of hydrochloric acid which use the Debye-Hückel theory as a basis for dealing with the unknown activity coefficients and are used to rationalize the dependence of the measured cell potential. It demonstrates how to set up two half cells in separate containers that are connected by a salt bridge containing aqueous solution of potassium chloride in order to measure a cell potential.
Further applications
Authors: Compton Richard G , Sanders Giles H W
Published: September 2023

This chapter highlights some applications of electrode potentials by firstly considering membrane potentials. It illustrates a cation exchange membrane through an example of sodium cations that pass through the membrane which is considered impermeable to the solvent, anions, and cations. It also refers to a membrane that contain fixed or immobile anionic sites with which cations in the membrane are loosely chemically bonded. The chapter analyses the exposure of both sides of the membrane to different aqueous solutions that contain sodium cations, which causes the equilibrium to be established at each solution/membrane interface. It discusses aqueous solutions which contain anions for reasons of electroneutrality and are assumed to be excluded from the membrane.
Synthetic aspects 1. The free ligands
Authors: Constable Edwin C.
Published: September 2023

This chapter examines free ligands, introducing some of the methods which are used for the synthesis of macrocyclic ligands. It begins by considering non-templated syntheses of free ligands. The expression 'non-templated' refers to the traditional approach to the synthesis of coordination compounds in which the final step of the reaction involves the reaction of a pre-formed organic ligand with an appropriate metal source. It is a pre-requisite of this approach that the organic ligand must be stable and isolable, and the first step in much coordination chemistry involves time-consuming ligand synthesis. The chapter then discusses ring-formation reactions; cases when high dilution reactions are not necessary; and the synthesis of crown ethers and the recognition of their unique properties, which played a very important role in the development of macrocyclic chemistry.
Introduction
Authors: Guy H. Grant , W. Graham Richards
Published: September 2023

This introductory chapter provides an overview of computational chemistry, which is one of the fastest growing areas of chemistry. Although there are specialists in the field, increasingly the techniques are applied by experimental chemists using the ever-growing power of ever-cheaper computers. Ultimately, computational chemistry involves taking known theory and developing the computer software to solve chemical problems. The chapter then looks at the computer hardware and software that many computational chemists use. The main classes of problems which can be resolved by computer include single molecule calculations, assemblies of molecules, and reactions of molecules. Every time a significant advance has been made in computing technology or in application, computational chemists have seized the opportunity and incorporated it into their own field. The chapter considers two examples to illustrate this: computer graphics and neural networks.
Quantum mechanics
Authors: Guy H. Grant , W. Graham Richards
Published: September 2023

This chapter discusses quantum mechanics. Quantum mechanics provides molecular wave functions in the form of coefficients which multiply known basis functions. The wave functions which satisfy the Schrödinger equation for the hydrogen atom are sometimes called orbitals. A hydrogenic atomic orbital is thus merely a three-dimensional mathematical function from which we can calculate the energy or other properties of the single electron system. Most applications involve computing the energy of a molecule for a given arrangement of atomic nuclei. The calculations of energy properties are now of comparable accuracy to experimental determinations. This is certainly true for geometries and static properties, but reactivities are more of a problem. The chapter looks at spin-orbitals, molecular orbitals, matrix elements, and correlation energy.
Ligand design
Authors: Guy H. Grant , W. Graham Richards
Published: September 2023

This chapter explores the vast array of methods now available to facilitate the design of novel ligands for biomolecules, particularly putative drug molecules. By superimposing molecules one can define the most likely binding units (the pharmacophore) and the properties and volumes of other sites of the receptor. If the receptor structure is known, it can be mapped to show possible binding sites for particular functional groups. This can be treated as the equivalent of a pharmacophore for the purposes of database searches or as constraints for de novo ligand design. In the latter, a computer program attempts to fit molecular fragments between functional group binding sites to create new molecules, or alternatively, genetic algorithms can be used. The final test for any new molecule is whether it resembles the existing active molecules. Molecular similarity techniques allow both shape and electrostatic similarity to be quantified.