bluuebunny/crossref_metadata_2025 huggingface dataset:
Agostic interactions to angular overlap model
Authors: Mingos D.M.P.
Published: September 2023

This chapter begins by discussing agostic interactions, which formally increase the total valence electron count by two and may be viewed as a means of making the electron deficient molecule conform more closely to the Effective Atomic Number Rule. The interaction has approximately the same strength as a hydrogen bond. The occurrence of agostic interactions may be demonstrated unambiguously by neutron diffraction studies or circumstantial evidence may be accumulated from spectroscopic data. The chapter then looks at the angular overlap model, which is based on a very approximate form of molecular orbital theory. It is useful for accounting for the geometries of transition metal complexes and the relative positions of ligands in the spectrochemical series.
Ligand substitution reactions
Authors: Mingos D.M.P.
Published: September 2023

This chapter addresses ligand substitution reactions. Following the nomenclature proposed by Langford and Gray, substitution reactions of inorganic reactions are classified as associative, interchange, and dissociative. The chapter explains that in an associative mechanism the entering ligand binds to the central atom before any significant bond weakening to the leaving group occurs. It also notes that, in the case of a dissociative mechanism, the ligand departs before the entering group forms a significant bond with the central atom and an intermediate with a lower coordination number is formed. The formation of such an intermediate also results in two peaks in the reaction profile, but the activation energy leading to the intermediate is larger than for its decomposition. Finally, the chapter looks at rates of substitution of metal complexes.
Stereochemical non-rigidity to synergic bonding
Authors: Mingos D.M.P.
Published: September 2023

This chapter begins by reviewing stereochemical non-rigidity. It notes that, in summary, five coordinate complexes are generally stereochemically non-rigid because there are two alternative coordination geometries with similar energies. The interconversion of these polyhedra provides a mechanism for permuting the symmetry inequivalent atoms. The chapter explains that this process is intramolecular, and it may be effectively studied by variable temperature nuclear magnetic resonance measurements if the frequency of permuting the inequivalent nuclei has the same order of magnitude as the difference in resonance frequencies for the symmetry inequivalent nuclei. Then, the chapter looks at superconductors, symmetry, and synergic bonding.
Some direct product tables
Authors: Mingos D.M.P.
Published: September 2023

For C
2, C
3, C
6, D
3, C
2v, C
3v, C
6v, C
2h, C
3h
C
6h, D
3h, D...
Vibrational spectroscopy
Authors: Brisdon Alan K.
Published: September 2023

This chapter discusses vibrational spectroscopy, which was one of the first spectroscopic techniques to be widespread in its use, particularly infrared or IR spectroscopy—so called because of the region of the electromagnetic spectrum used. These forms of spectroscopy are tied up with changes in the vibrational state of molecules. The basis of the IR experiment is to pass infrared radiation through a thin sample of compound and measure which energies of the applied infrared radiation are transmitted by the sample. Infrared spectra can be recorded for solids, liquids, solutions, and gases using a variety of different sampling arrangements, but are probably most commonly recorded as liquids or solutions or of a solid which has been ground up with a mulling agent and pressed between two alkali halide plates. The chapter then considers a second form of vibrational spectroscopy—Raman spectroscopy—which provides similar information but has different physical basis.
Mass spectrometry
Authors: Brisdon Alan K.
Published: September 2023

This chapter focuses on mass spectrometry. Although mass spectrometry is not strictly a form of spectroscopy, in that it does not involve the interaction of radiation with matter, it is nonetheless a very useful method for identifying unknown compounds. One of the reasons it is so useful is that it can provide information about the relative molecular mass of a compound. In fact, mass spectroscopy will usually provide a lot more information than just the mass of compounds; it is frequently possible to determine which ligands or groups of atoms are bonded together from the way the compound breaks up or fragments during the experiment. Mass spectroscopy requires that the molecule of interest is charged; this then provides a basis for separating the different ions due to their mass-to-charge ratio. The chapter then looks at ionization methods and the interpretation of mass spectra.
Catalytic activity and selectivity
Authors: Bowker Michael
Published: September 2023

This chapter focuses on catalytic activity and selectivity. The most important feature of a catalyst is how well it does the job of converting reactants into products, and this is measured by two parameters: activity and selectivity. The activity of a catalyst is defined as the rate of consumption of reactant, whereas selectivity is the fraction of the total products which a particular substance represents. The chapter then looks at the catalytic parameters, including adsorption, simple reaction, bimolecular reactions, and temperature dependence of the rate. In general, more than one product is formed from any particular reaction, and only one of these is the desired product. The objective of the catalytic scientist, then, is to optimise the reaction for that desired product through the appropriate catalytic design. The chapter also examines forces on surfaces; weakly held states and surface diffusion; and surface dependence of reaction rates and the volcano principle.
Catalysis in everyday Iife
Authors: Bowker Michael
Published: September 2023

This chapter explores the role of catalysis in everyday life. Society is highly dependent on the chemical industry and the modern lifestyle would be impossible without this business. The vast majority of chemical products are formed using catalysis. One of the most directly evident everyday uses of catalysis has been given in the previous chapter: automobile catalysis. This is perhaps the catalytic technology of which people are most aware nowadays. However, there is a wide range of catalytic processes which are used to make everyday products, some of which are a surprise. The chapter then looks at fertilizer production; margarine production by hydrogenating vegetable oil; formaldehyde production; the production of fibres and plastics; washing powder additives; the production of sweet drinks; and the production of pharmaceuticals by asymmetric synthesis.
Reactions of nucleophiles with other carboxylic acid derivatives
Authors: Jones John
Published: September 2023

This chapter focuses on reactions of nucleophiles with other carboxylic acid derivatives. The esters which were considered in the previous chapter lie roughly in the middle of a reactivity series in which the ease of nucleophilic attack at the carbonyl carbon decreases from left to right. Thiol esters are between ordinary esters and carboxylic acid anhydrides in reactivity. The carboxylic acids themselves are the least reactive because they are converted to carboxylate complexes on which nucleophilic attack is very difficult. The chapter then looks at amides. Ammonia and amines simply form salts with carboxylic acids, and these are stable except at high temperatures. Acyl chlorides react very easily with ammonia and amines.
Enols and enolates
Authors: Jones John
Published: September 2023

This chapter assesses enols and enolates. An aqueous solution of a simple ketone such as acetone is a surprisingly complex system. In addition to the reversible hydration of the keto form, it is in equilibrium with an enol tautomer and an enolate ion. At equilibrium, the concentrations of enol and enolate are very small in this case. As such, the conjugate base derived from acetone can only exist at trace concentrations in aqueous or alcoholic solution. In principle, all carbonyl compounds can form enols and enolates. The chapter then looks at simple enol and enolate reactions; enols and enolates both react with electrophiles.
Conduction
Authors: Winterton R. H. S.
Published: September 2023

This chapter delves into the process of conduction during heat transfer. It explains that conduction heat transfer is the flow of kinetic energy from one molecule to the next by direct contact between the two. At the molecular level the internal energy of a material can be regarded as that same kinetic energy, as found in atoms and molecules. The chapter then turns to steady state conduction, providing straightforward cases in simple one-dimensional geometries. The chapter imagines a scenario where these assumptions are not justified, and it provides a more basic approach in the form of a general differential equation that always applies and then solves it using the boundary conditions of the particular problem. Finally, transient problems — time-varying, heat conduction problems — are explored.
Forced convection
Authors: Winterton R. H. S.
Published: September 2023

This chapter turns to forced convection. Instead of buoyancy forces, forced convection is a mechanism caused by pumps or fans. This concept is explained through a quick primer on fluid mechanics. Then, the chapter defines the heat transfer coefficient. Afterward, it explores the heat transfer correlations for external flow and for turbulent flow of non-metals in ducts. Correlations for the turbulent flow of liquid metals in ducts as well as laminar flow in ducts are also examined. Finally, the chapter discusses temperature transients and their complexities, including the lumped parameter approximation, before closing with heat exchangers and the log mean temperature difference.
Fundamentals of thermal radiation
Authors: Jones H. R. N.
Published: September 2023

This chapter provides a background on thermal radiation, which is considered as the third mechanism of heat transfer after conduction and convection. It explains that the transfer of heat is a mechanism of energy transfer and is aimed at achieving thermal equilibrium and equal temperatures. It also points out that thermal radiation is an emission of electromagnetic waves which can be transferred between two bodies even if they are separated by a vacuum. The chapter considers thermal radiation as an electromagnetic radiation that is attributed to velocity, frequency, and wavelength. It discusses the radiation emitted and not equally distributed over a wide range of wavelengths, which is referred to as spectral distribution or spectrum.
View factors
Authors: Jones H. R. N.
Published: September 2023

This chapter focuses on radiative transfer from one surface to another, as the surface generally emits radiation in all directions simultaneously. It explains how the radiation leaving the source will impinge on the receiving surface if the receiving surface is located some distance away from the radiation source. It also highlights the concept of view factor, which takes the geometry of the thermal radiation system into account. The chapter cites several examples of a view factor chart, where the view factor is plotted as a function of the geometry or two parallel plates and two perpendicular plates. It mentions the Cosine Law that provides the method for calculating any view factor where the geometry is defined.
Measurement of temperature
Authors: Jones H. R. N.
Published: September 2023

This chapter discusses general types of techniques used for the measurement of temperature. It describes intrusive methods, such as thermometers and thermocouples, that involve the introduction into the system of a probe or detector whose output signal gives an indication of the temperature. It also mentions non-intrusive methods, such as pyrometers, radiometers, and modern laser-based systems, that are normally used where the temperatures are too high or the environment too hostile for a probe. The chapter considers methods of temperature measurement that are based on the emission or absorption of thermal radiation. It uses some form of heat transfer analysis in order to extract correct temperature information, which involves a combination of all heat transfer mechanisms.
Molecular geometry: VSEPR
Authors: Winter Mark J.
Published: September 2023

This chapter focuses on the VSEPR (valence shell electron pair repulsion) method. The VSEPR method is a simple algorithm to determine the geometry and shape of main group compounds based upon their Lewis structure. Bonding pairs of electrons and lone pairs attached to a central atom are distributed in space so as to minimize electron–electron repulsions between all the attached bonding and lone pairs. Double and triple bonds only occupy one vertex, while lone pairs and multiple bonds take up more room than bonding pairs. Lone pairs in trigonal bipyramidal compounds are always located in the equatorial sites. Predicted geometries for d-block complexes are usually those associated with spreading the attached groups (ligands) as far away from each other as possible.
Product operators I
Authors: Hore P. J. , Jones J. A. , Wimperis S.
Published: September 2023

Introduction

Product operators became popular as a way of describing NMR experiments after the publication of a review article by Ernst’s group. As the word ‘operator’ indicates, they are inherently quantum-mechanical in nature; however, they can be successfully used with no quantum-mechanical knowledge whatsoever. All...
Weak coupling
Authors: Hore P. J. , Jones J. A. , Wimperis S.
Published: September 2023

Introduction

We have now seen all the machinery needed to use density matrices to predict the behaviour of isolated nuclei. As in the case of product operators, the density matrix approach reassuringly reproduces the results of the vector model. With two or more coupled spins,...
The drug discovery process
Authors: Patrick Graham L.
Published: September 2023

This chapter focuses on the drug discovery process. It recognises howrecognizes that synthesis has played a vital role in the discovery of drugs—first in the context of in line with creating analogues of clinically important natural products, known as semi-synthetic agents, and semi-synthetic agentslater in the development of entirely synthetic drugs. The chapter discusses the history of developing drugs by referencing the usage of a placebo effect, morphine, penicillin, and high throughput screening. It includes howintroduces the discipline of medicinal chemistry, which involves the design and synthesis of novel pharmaceuticals. Additionally, the chapter looks into at the identification of a drug target such as receptors, enzymes, and transport proteins. It explores the overall drug design and development process, wherein organic synthesis had plays a crucial role. The chapter also includes discusses drug testing and how novel drugs are patented before clinical trials.
Cyclic systems in drug synthesis
Authors: Patrick Graham L.
Published: September 2023

This chapter explores cyclic systems in drug synthesis. It notes the vital role that cyclic systems play in drug structures which would be referred to as carbocyclic or heterocyclic. Additionally, the chapter notes that the ring systems made up of carbon atoms could can vary in sizes as well. It highlights the importance of ring systems in terms of ensuring binding groups are correctly positioned as ideal scaffolds. The chapter also discusses the two synthetic strategies that would ensure that cyclic structures can be introduced into a drug structure. It notes thediscusses examples of syntheses involving intramolecular cyclisationscyclizations, concerted intermolecular cyclisationscyclizations, intermolecular coupling, and cyclisation cyclization reactions. Moreover, it looks into at the synthesis of dihydropyridines.
Erythromycin and macrolide antibacterial agents
Authors: Patrick Graham L.
Published: September 2023

This chapter looks atinto erythromycin and macrolide antibacterial agents. It highlights the importance of erythromycin, which as it is the third most widely used class of antibiotics. Additionally, eErythromycin is a natural product produced by a bacterial strain called Saccharopolyspora eythraea.. The chapter then explores the synthesis, biosynthesis, and analogues of erythromycin. On the other hand, mMacrolides are extremely useful antibacterial agents, however,but they have complex structures with limited analogueswhich limits the number and variety of analogues that can be made. The chapter also looks intoconsiders how clinically important analogues of erythromycin have been prepared by semi-synthetic methods and modified to avoid an acid-catalysed intramolecular reaction that would result in inactive compounds.
The Central Dogma of Molecular Biology
Authors: Meneely Philip , Hoang Rachel Dawes , Hoang Rachel Dawes , Okeke Iruka N. , Heston Katherine
Published: September 2023

This chapter explains that the Central Dogma of molecular biology is that DNA provides the template to make RNA, which provides the template to make a polypeptide that contributes to phenotypes. It illustrates the structure of DNA and the Central Dogma, highlighting features of the DNA molecule that have an impact on its function. It points out modifications to the traditional view of the Central Dogma and introduces the basic structure of a gene. The chapter describes information content that flows from DNA to RNA to polypeptide, which is inherent in the structures of the molecules and encodes the amino acid sequence of the polypeptide. It also shows that, according to genome analysis, a surprising number of RNA molecules do not serve as templates for making polypeptides but are functional themselves.
Genome Structure, Organization, and Variation
Authors: Meneely Philip , Hoang Rachel Dawes , Hoang Rachel Dawes , Okeke Iruka N. , Heston Katherine
Published: September 2023

This chapter covers the structure of the genome and the variation in genome organization found in different species, which are both the outcome of, and the ingredients for, natural selection. It discusses the structure of chromosomes, extrachromosomal DNA, changes in the genome, and integration of genomic findings with evolutionary and genetic principles. It also reviews the DNA sequence of an organism, which encodes the information that underpins and directs most of the biological processes taking place within that organism. The chapter points out that genomes of different species differ in their DNA sequences and in the organization of their genes and other genetic elements. It connects genomic information with well-defined evolutionary and genetic concepts, providing a framework to weave together the details of genetics, genomes, and evolution.
Descent with Modification: Continuity and Variation in the Genome
Authors: Meneely Philip , Hoang Rachel Dawes , Hoang Rachel Dawes , Okeke Iruka N. , Heston Katherine
Published: September 2023

This chapter talks about DNA replication, and it repairs and ties this topic to Charles Darwin’s concept of ‘descent with modification’, a fundamental principle of natural selection and evolution. It presents several challenges to DNA replication that arise from its length and anti-parallel structure, including the processes that have evolved to address these challenges. It also introduces the many types of mutation that occur, and how the occurrence of such mutations and the effects of selection can be revealed by comparing the genomes of different organisms. The chapter shows how to reconstruct evolutionary history and develop phylogenetic trees based on DNA sequence changes. It highlights the principle of descent with modification, which demonstrates the balance between two competing evolutionary pressures.
The Inheritance of Single-gene Traits
Authors: Meneely Philip , Hoang Rachel Dawes , Hoang Rachel Dawes , Okeke Iruka N. , Heston Katherine
Published: September 2023

This chapter considers gene expression in its most general sense, which is a gene that produces a product, such as RNA or protein, that results in a change within a cell. It explains how the cellular activity influences the physical traits or the morphology of an organism, noting that the expression of genes provides the heritable component of the morphological diversity necessary for evolutionary change. It also discusses the physical traits or phenotypes that are used as tools to monitor inheritance, which are produced by the expression of genes. The chapter stresses that the inheritance patterns of individual genes are predictable and can be tracked by well-chosen phenotypes. It describes the predictable inheritance pattern of genes that arises from the behaviour of chromosomes during meiosis.
The Cellular Basis for Mendelian Genetics
Authors: Meneely Philip , Hoang Rachel Dawes , Hoang Rachel Dawes , Okeke Iruka N. , Heston Katherine
Published: September 2023

The chapter examines the process of meiosis, which discusses on a cellular and molecular level the inheritance patterns that Gregor Mendel observed. It shows how the genome of the cell is halved during meiosis, with each resulting cell containing one of the two members of a homologous pair of chromosomes. It also recounts the biologists that recognized Mendel’s patterns of inheritance and that the segregation of chromosomes during meiosis were two sides of the same biological coin. The chapter describes the behaviour of chromosomes during meiosis, which is the cellular basis of Mendel’s Law of Segregation that states that alleles for each gene separate from each other during the production of gametes. It clarifies how the Mendelian inheritance can be integrated with the observed movement of chromosomes in meiosis and the changes in DNA during the process of gamete production.
Transcription: Reading and Expressing Genes
Authors: Meneely Philip , Hoang Rachel Dawes , Hoang Rachel Dawes , Okeke Iruka N. , Heston Katherine
Published: September 2023

This chapter discusses the DNA sequence that comprises a gene which is expressed by the transcription of the gene into an RNA molecule. It details the regulation of transcription and describes cells with the same DNA sequence that have different appearances and functions because they transcribe different genes. It also considers transcript initiation as the key step through which gene expression can be controlled, noting that the transcription processes that are regulated by the cell are also those that have been subject to the most evolutionary variation. The chapter deals with gene expression, which is the process of transcribing a subset of the genes in a genome into RNA to mediate a biological function that differs across time and space. It looks at the processes of gene expression that provide the framework to highlight the many opportunities for control and evolutionary change.
The Engine of Evolution
Authors: Bell Graham
Published: September 2023

This chapter discusses two basic processes that underlie evolutionary change: variation and selection. Mutations do not systematically lead to improvements, and mutation alone therefore cannot cause adaptation. Instead, mutation leads to variation so that a population contains many different kinds of individuals. A few of these may be better than the rest, at least in some circumstances, and are able to grow and reproduce more rapidly. This creates a process of selection that is responsible for driving evolution in a particular direction. The key is to realize that, at any given time, selection always modifies the changed state that has been produced by the previous episode of selection. This is the principle of cumulation. The chapter then looks at incorporation and evolution.
Artificial Selection
Authors: Bell Graham
Published: September 2023

This chapter highlights artificial selection—the deliberate choice of certain individuals to propagate a line. This has been the mechanism for producing all the modern varieties of domestic animals and crop plants. Indeed, the application of evolutionary principles to practical problems has been essential to the great expansion of agricultural productivity on which modern civilization is based. At the same time, artificial selection is itself a powerful method for investigating these principles. The chapter then looks at how artificial selection produces rapid and predictable change in the short term and considers domestication as applied artificial selection. It also examines how artificial selection can produce extensive adaptive radiations.
Cooperation and Conflict
Authors: Bell Graham
Published: September 2023

This chapter demonstrates how natural selection can lead to the evolution of helpful behaviour in certain kinds of society. Unqualified exploitation or aggression needs no special explanation: it is easy to understand that selection will often favour the selfish pursuit of individual interest. There are other features of organisms, however, that cannot be readily explained in this way. The most interesting involve social behaviour, and especially any behaviour that involves a degree of helpfulness or cooperation among individuals. The chapter begins with the simplest possible situation, involving bacterial cultures where social relations are of the simplest kind. Simple as they are, they show how much more complicated kinds of society can be understood. The chapter then considers how social interactions introduce a new aspect of adaptation and how altruism evolves only in family groups.
Calciviruses: norovirus causing vomiting and diarrhoea
Authors: Oxford John , Kellam Paul , Collier Leslie
Published: September 2023

This chapter investigates caliciviruses. These are global in prevalence and depend on faecaloral spread coupled with poor hygiene. They are notorious in causing serious gastroenteritis outbreaks on cruise ships and in restaurants, hospitals, schools, and military camps. Other members of the calicivirus family infect cattle, pigs, mice, and cats. The chapter talks about the clinical impact of caliciviruses on the immunosuppressed patients of developing countries. Developing countries experience 200,000 deaths among children under the age of five from noroviruses per year, but these viruses continue to be an under-investigated family due to the lack of cell-culture systems. The chapter covers the classification, morphology, genome, replication, and clinical and epidemiological aspects of caliciviruses.
Differentiation II
Authors: Monk Paul , Munro Lindsey J.
Published: September 2023

This chapter begins by demonstrating the process of differentiating exponential functions. It differentiates between the Taylor series and Maclaurin series way of writing functions. A Taylor series is a way of writing a function with an infinite sum of terms, while a Maclaurin series is a Taylor series that is centred at zero. We can use Maclaurin series to represent simple functions from across many branches of mathematics, such as exponentials and trigonometry. The chapter then considers the process of differentiating logarithmic functions and trigonometric functions. To obtain the derivative of a sine or a cosine, we must express the angle in radians rather than straightforward degrees. We must then convert all degrees to radians before differentiating a trigonometric function.
Differentiation III
Authors: Monk Paul , Munro Lindsey J.
Published: September 2023

This chapter explains the process of differentiating functions of functions, considering the chain rule. Sometimes, an equation does not contain a single, simple function but two functions. It is a function of a second but different function; the first function acts as the argument to the second. We often call these collections a chain. We need to identify the two functions involved before we differentiate a function of a function. If we see brackets and the symbol of one of the functions outside it, then the first function is the one inside the bracket while the second operates on the bracket, treating it as an argument.
Differentiation VI
Authors: Monk Paul , Munro Lindsey J.
Published: September 2023

This chapter evaluates partial differentiation. We give the name partial derivative to expressions like (∂y/∂x) because we take the gradient from only one part of a larger graph. It is incomplete, and therefore ‘partial’. Differentiating to form a partial derivative is conceptually identical to the normal process of differentiation. The chapter then looks at the total differential and higher-order partial derivatives. The total differential expresses the change in a physicochemical variable. It is expressed in terms of the individual changes in the function due to each variable. Finally, the chapter considers del ∇ and the Laplacian operator. The Laplacian operator is an abbreviation for a partial derivative expression.
Graphs III
Authors: Monk Paul , Munro Lindsey J.
Published: September 2023

This chapter evaluates the process of obtaining linear graphs from non-linear functions. It is often difficult to obtain equations that successfully describe a curved line. This difficulty can prevent us from understanding the underlying chemistry and hence prevent us from determining what is happening at a microscopic level. Linearizing a graph and obtaining the values of the gradient and intercept helps us describe a previously curved line in a way that is easier to interpret. With a meaningful equation, we have a powerful tool for understanding the processes occurring in the equation they describe. The chapter then looks at the process of linearizing power equations and exponential equations.
Statistics II
Authors: Monk Paul , Munro Lindsey J.
Published: September 2023

This chapter describes the treatment and assessment of errors. All real experimental data have an associated error. This error means that all literature data comprise a range of values. We sometimes refer to the relative magnitudes of the reading and the error in terms of the signal-to-noise ratio, where the reading is the ‘signal’ part. All experimental apparatus has a recommended range of values. As such, analysts should ensure the experimental readings lie within the recommended range of the apparatus. The chapter then looks at the process of quantifying the innate error of a linear function and a non-linear function. It also considers the graphical treatment of errors and the correlation coefficient.
Diagnostic cytopathology
Authors: Evered Andrew
Published: September 2023

This chapter deals with diagnostic cytopathology, which is the diagnosis of disease at the cellular level and involves the preservation, staining, and microscopic examination of cells that have been extracted from the body. It looks at a variety of human diseases that can be diagnosed with diagnostic cytopathology, such as infections, crystal deposition diseases, and benign tumours. It also outlines the two modalities in which diagnostic cytopathology may be used: as a screening test for the early detection of precancerous lesions in asymptomatic individuals, and as a diagnostic test for the identification of cancer cells in symptomatic patients. The chapter illustrates that the microscopic interpretation of cells taken from the human body is often not straightforward. It explains that inflammatory disease, cell degeneration, regenerative process, and a wide array of benign conditions represent pitfalls which can entrap the unwary or inexperienced cytologist.
Landscape Ecology and Management
Authors: Goodenough Anne E. , Hart Adam G.
Published: September 2023

This chapter discusses the management of species over space. It looks at elements of landscapes ranging from patches, background matrix, linear features, and boundaries. The chapter notes study patterns in landscape ecology. It includes the spatial patterns of species and individuals by listing the terms of mapping range, species range, species distribution, home range, and movement. The chapter notes the impact of landscape processes such as habitat loss and fragmentation. It also includes the effects of non-landscape processes like climate change. The chapter expounds on the management of landscape ecology by referring to heterogeneity, connectivity, preventing species movement, and ecoregions. In addition, it presents an interview with applied ecologist Peter Fretwell.
Non-native Species Management
Authors: Goodenough Anne E. , Hart Adam G.
Published: September 2023

This chapter looks at the management of non-native species. It starts by explaining the human practice of moving non-native species in terms of temporal scale and spatial scale. The chapter highlights the importance of non-native species in applied ecology. Then, it explains the process of introducing species to a new location, which is called translocation. The chapter warns of a possible invasion meltdown amidst the moving process and lists the impacts of non-native species. The chapter mentions the importance of monitoring and management while acknowledging the role of citizen science. It also considers that controlling non-native species can be counter-productive. The chapter includes an interview with applied ecologist Helen Roy.
Principles of Conservation
Authors: Goodenough Anne E. , Hart Adam G.
Published: September 2023

This chapter explores principles of conservation. It acknowledges the concept and risk of mass extinction and explains the importance of conservation ecology. The conservation scale is best observed by looking at statistics of magnitude and geographical spread of current efforts, need for further action, and monetary costs. Then, the chapter differentiates between conservation and preservation. It highlights the focus of conservation, whether it is targeting a single species or communities of them. The chapter discusses the factors threatening population conservation, which range from natural abiotic and natural biotic to anthropogenic factors. Moreover, the best-known international species-at-risk systems are introduced, namely the International Union for the Conservation of Nature (IUCN) red list and the NatureServe Imperiled list. These aim to quantify species' extinction risk. The chapter then discusses conservation strategies as well as conservation triage. It includes an interview with applied ecologist Paul Butler.
Anisotropic EPR spectra in the solid state
Authors: Chechik Victor , Carter Emma , Murphy Damien
Published: September 2023

This chapter explores the origins of the anisotropies in g and A for a spin. It explains how symmetry derived anisotropies in the solid state are manifested through g and how the interpretation of this tensor provides valuable information on the symmetry of the paramagnetic centre. It also concentrates on the lineshapes for powder spectra and the origins of the hyperfine A tensor. The chapter considers the electron paramagnetic resonance (EPR) spectra of a paramagnetic vanadyl and presents the theory explaining the origins of anisotropies. It describes a tensor as a mathematical object that illustrates a physical property and outlines the rank of the tensor that depends on the number of directions needed to describe that property.
Systems with multiple unpaired electrons
Authors: Chechik Victor , Carter Emma , Murphy Damien
Published: September 2023

This chapter examines the spin–spin interaction between the unpaired electron and nuclei with spin I not equal to 0. This results in splitting of electron paramagnetic resonance (EPR) signals into hyperfine patterns. It discusses how spin–spin interaction between unpaired electrons affects EPR spectra in several important systems, such as liquid or frozen solutions of paramagnetic compounds at high concentration and organic molecules with two or more unpaired electrons. It also outlines the basic principles of electron spin–electron spin interactions which are somewhat similar to the electron spin–nuclear spin interaction. The chapter considers the EPR spectra of systems with multiple unpaired electrons. It describes the underlying theory that is supplemented by examination of EPR spectra for each type of system.
Linewidth of EPR spectra
Authors: Chechik Victor , Carter Emma , Murphy Damien
Published: September 2023

This chapter highlights the importance of linewidth as a parameter in electron paramagnetic resonance (EPR) spectroscopy, describing narrow lines that are saturated or distorted if incorrect spectrometer parameters are chosen. It describes broad lines as difficult to distinguish from the background, particularly if the intensity is not very high. It also analyses linewidth measurements that provide important information about the structure and dynamics of the spin system. The chapter looks at a few important relaxation mechanisms that contribute to the linewidth. It illustrates how it is not possible for a complex spectra, such as anisotropic patterns, to extract the linewidth directly and notes that information about linewidth can be obtained through spectral simulations.
Elements of Physical Chemistry
Authors: Atkins Peter , de Paula Julio , Smith David
Published: September 2023

Elements of Physical Chemistry begins with an examination of the properties of gases. It then looks at the first law of thermodynamics and the second law of thermodynamics. Next it moves on to physical transformations, chemical change, chemical kinetics, and quantum theory. There are also chapters on atomic structure, the chemical bond, molecular interactions, molecular spectroscopy, and statistical thermodynamics. Other topics include magnetic resonance, macromolecules and aggregates, and solids.
Entropy
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter begins by defining spontaneous change, which is a change that has a tendency to occur without work having to be done to bring it about. The apparent driving force of spontaneous change is the tendency of energy to disperse and matter to become disordered. The measure of dispersal used in thermodynamics is called entropy. When matter and energy become dispersed, entropy increases. That being so, the basic principle underlying change can be expressed as the second law of thermodynamics: entropy of an isolated system tends to increase. The tendency of energy to disperse explains the fact that, despite numerous attempts, it has proved impossible to construct an engine in which heat, perhaps from the combustion of a fuel, is drawn from a hot reservoir and completely converted into work, such as the work of moving an automobile.
Phase diagrams of pure substances
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter demonstrates the phase diagrams of pure substances. The phase diagram of a substance is a map showing the conditions of temperature and pressure at which its various phases are thermodynamically most stable. The boundaries between regions in a phase diagram, which are called phase boundaries, show the values of p (pressure) and T (temperature) at which the two neighbouring phases are in equilibrium. The pressure of the vapour in equilibrium with its condensed phase is called the vapour pressure of the substance. The chapter then looks at how the slope of a phase boundary is given by the Clapeyron equation, and how the slope of the liquid–vapour phase boundary is given by the Clausius–Clapeyron equation. It also considers the boiling temperature and the normal boiling point; the freezing temperature; the critical temperature; the critical pressure; and the phase rule.
The approach to equilibrium
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter addresses how all forward reactions are accompanied by their reverse reactions. Close to the start of a reaction, when little or no product is present, the rate of the reverse reaction is negligible. However, as the concentration of products increases, the rate at which they decompose into reactants becomes greater. At equilibrium, the reverse rate matches the forward rate and the reactants and products are present in abundances given by the equilibrium constant for the reaction. The chapter then considers the term relaxation, which denotes the return of a system to equilibrium. It is used in chemical kinetics to indicate that an externally applied influence has shifted the equilibrium position of a reaction, normally abruptly, and that the reaction is adjusting to the equilibrium composition characteristic of the new conditions. Relaxation methods include the temperature jump technique.
Translation
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter describes a particle confined to a finite region of space that can possess only certain discrete energies. It also looks at the corresponding wavefunctions. It analyzes the quantization of energy that emerges as a natural consequence of solving the Schrödinger equation and the conditions imposed on it. It also introduces a striking non-classical feature of small particles, which describes their ability to penetrate into and through regions where classical physics would forbid them to be found. The chapter talks about the translational energy levels of a particle which are confined to a finite region of space and are quantized. It explores how quantum mechanics reveal the ability of a particle to penetrate into and through regions where classical physics would forbid it to be found.
Many-electron atoms
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter focuses on the many-electron atom which is an atom or ion with more than one electron, which includes all neutral atoms other than H. It investigates how hydrogenic atomic orbitals are used in conjunction with the concept of spin and the Pauli exclusion principle to describe their structures. It also studies electrons that occupy the lowest energy available orbitals and are subject to the requirements of the Pauli exclusion principle. The chapter looks at the Schrödinger equation for a many-electron atom and shows how it is highly complicated because all the electrons interact with one another. The chapter analyzes modern computational techniques which refine approximations and permit highly accurate numerical calculations of energies and wavefunctions.
Periodic trends of atomic properties
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter accounts for the periodicity of atomic properties and the structure of the periodic table, including atomic and ionic radii, ionization energies, and electron affinities. It analyzes trends in the variation of atomic and ionic radii and ionization energies which can be correlated with the effective nuclear charges of atoms. It also discusses the periodic recurrence of analogous ground-state electron configurations wherein the atomic number increases accounts for the periodic variation in the properties of atoms. The chapter emphasizes two aspects of atomic periodicity which can be correlated with the effective nuclear charge: atomic and ionic radius and ionization energy. It looks at the atomic radius of an element that is half the distance between the centres of neighbouring atoms in a solid or in a homonuclear molecule.
Molecular orbital theory: heteronuclear diatomics
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter looks at the molecular orbital theory (MO theory) of heteronuclear diatomic molecules and ions, which introduces the possibility that atomic orbitals on two atoms contribute unequally to the molecular orbital. It points out how polarity can be expressed in terms of the concept of electronegativity. It also examines the bonding molecular orbital of a heteronuclear diatomic molecule or ion which is composed mostly of the atomic orbital of the more electronegative atom. The chapter describes the electron distribution in the covalent bond between the atoms in a heteronuclear species, which is considered not symmetrical between the atoms as it is energetically favourable for a bonding electron pair to be found closer to one atom rather than the other. It mentions the polar bond, which is a covalent bond in which the electron pair is shared unequally by two atoms.
Interactions between molecules
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter looks at liquids and solids which are bound together by one or more cohesive interactions, such as van der Waals interactions, hydrogen bonding, and hydrophobic effect. It describes the strengths of the various van der Waals interactions, which are related to dipole moments and polarizabilities. It also explains how van der Waals interactions exclude interactions which result from the formation of covalent or ionic bonds and are restricted to interactions for which the potential energy is inversely proportional to the sixth power of the separation of the molecules. The chapter discusses how attractive interactions result in cohesion, while repulsive interactions prevent the complete collapse of matter to nuclear densities. It looks at several types of molecular interactions responsible for the formation of condensed phases and large molecular assemblies.
The decay of excited states
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter investigates two modes of radiative decay in which radiation is emitted spontaneously by molecules in excited states: fluorescence and phosphorescence. It discusses the reduction in efficiency of emission through quenching, which is interpreted in terms of the rates of physical and chemical processes that compete for the energy stored in excited states of molecules. It also highlights the detection of photons that are emitted when excited electronic states decay radiatively back to the ground state. The chapter looks at how molecules in excited electronic states discard their excess energy by emission of electromagnetic radiation, transfer as heat to the surroundings, fragmentation, or reaction. It describes the excitation energy of a molecule that has absorbed a photon and is degraded into the disordered thermal motion of its surroundings by non-radiative decay.
The Boltzmann distribution
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter highlights the Boltzmann distribution, which is used to predict the populations of states in systems at thermal equilibrium. It considers the Boltzmann distribution as one of the most important equations in chemistry as it summarizes the populations of states and provides insight into the nature of temperature. It also reviews how thermodynamic properties, the temperature dependence of equilibrium constants, and the rates of chemical reactions can be interpreted in their terms. The chapter recognizes temperature as the most probable distribution of molecules over the available energy levels subject to certain restraints. It looks at the concept of the Boltzmann distribution that underlie all the descriptions of the relation between the individual properties of molecules and the properties of bulk matter.
Crystal structure
Authors: Atkins Peter , Paula Julio de , Smith David
Published: September 2023

This chapter describes the structures of crystalline solids, which are of considerable practical importance as they have implications for geology, materials, and technologically advanced materials. It explores the regular arrangement of atoms in periodic crystals that can be expressed in terms of unit cells and determined by diffraction techniques. It also considers a crystal structure as nature's solution to the problem of condensing objects of various shapes into an aggregate of minimum energy and, for temperatures above zero, of minimum Gibbs energy. The chapter covers the basic principles of X-ray diffraction, which is a hugely important technique for determining crystal structure, and the interpretation of the diffraction pattern. It includes the structures of metallic, ionic, and molecular solids to account for the mechanical, electrical, optical, and magnetic properties that form the basis of new materials and new technologies.