bluuebunny/crossref_metadata_2025 huggingface dataset:
Catalysis by Solids, 1 : Organic Intermediates and Fine Chemicals
Authors: Doraiswamy L. K.
Published: November 2020

The use of solid catalysts has a number of advantages compared to catalysis in solution. The most important advantage is their discrete state, usually stationary, which enables easy separation of the product from the catalyst. Although catalysis by solids in organic technology was largely restricted till about the mid-1970s to bulk chemicals produced by continuous processes, it has since been extended to organic intermediates and fine chemicals (which are usually medium to small-volume production in batch processes). We devote this chapter to a brief review of the major types of solid catalysts used in the production of intermediates and fine chemicals. Though these reactions can be carried out in both the vapor and liquid phases, the substrates used in organic synthesis are often relatively complex liquid molecules which tend to decompose under harsh conditions. Hence it is usually desirable to operate under softer conditions, thus preserving the liquid state of the substrate and preventing any likely decomposition to unwanted products. Because catalysis by solids will almost certainly play a major role in organic syntheses of the future, surface science studies involving complex organic molecules are being increasingly undertaken (see, e.g., Rylander, 1979, 1985; Molnar, 1985; Kim and Barteau, 1989; Joyner, 1990; Idriss et al., 1992; Schulz and Cox, 1992, 1993; Pierce and Barteau, 1995; and the recent review by Smith, 1996). However, this book will not be concerned with such mechanistic considerations. There are a few classes of catalysts that have acquired a degree of prominence during the last decade in the synthesis of organic intermediates and fine chemicals that marks them as uniquely relevant in the context of industry’s irreversible shift to green technology. In addition to the homogeneous catalysts considered subsequently in Chapter 9, they include a wide variety of solid catalysts. These catalysts can be classified in two ways: (1) as distinct classes of catalysts that cut across different types of reactions, including dissolved catalysts supported on solids; and (2) as catalysts specific to different types of reactions. It is also possible to control catalytic action by using appropriate solvents/additives.
Reactor Design for Complex Reactions
Authors: Doraiswamy L. K.
Published: November 2020

Procedures were formulated in Chapter 5 for treating complex reactions. We now turn to the design of reactors for such reactions. Continuing with the ethylation reaction, we consider the following reactor types for which design procedures were formulated earlier in Chapter 4 for simple reactions: batch reactors, continuous stirred reactors (or mixed-flow reactors), and plug-flow reactors. However, we use the following less formal nomenclature: A = aniline, B = ethanol, C = monoethyaniline, D = water, E = diethylaniline, F = diethyl ether, and G = ethylene. The four independent reactions then become Using this set of equations as the basis, we now formulate design equations for various reactor types. Detailed expositions of the theory are presented in a number of books, in particular Aris (1965, 1969) and Nauman (1987). Consider a reaction network consisting of N components and M reactions. A set of N ordinary differential equations, one for each component, would be necessary to mathematically describe this system. They may be concisely expressed in the form of Equation 5.5 (Chapter 5), or . . . d(cV)/dt = vrV (11.1) . . . The use of this equation in developing batch reactor equations for a typical complex reaction is illustrated in Example 11.1.
Bioorganic Synthesis Engineering
Authors: Doraiswamy L. K.
Published: November 2020

Biological processes, from the simplest to the most complex, can broadly be classified as those caused by the catalytic action of living entities known as microorganisms or microbes, and those promoted and catalyzed by “lifeless substances” produced by microorganisms, known as enzymes. The two together are often referred to as biocatalysts. The microbial kingdom of living entities consists of all living things with a very simple biological organization. Both microbes and enzymes can be used to promote or selectively achieve a wide range of chemical transformations. Indeed, biocatalysts occupy a unique position in the wide spectrum of catalysts used in organic technology and synthesis. One of the chief beneficiaries of the rising emphasis on environmentally friendly processes is the enzyme, for it is being increasingly pressed into service to generate technologies that are both highly selective and pollution free. As catalysts, enzymes accelerate the rates of reactions at milder conditions, are highly selective, are biodegradable, and can be used in “free” solution form or as immobilized heterogeneous catalysts. The last feature, their use in immobilized form, has been a major factor in the movement of the enzyme from laboratory to industry. Two main shortcomings of the conventional enzyme that have limited its application in organic synthesis are its restriction to reactions in the aqueous phase and to very mild temperatures and pressures. Research in the last few years has “released” the enzyme from these restrictions (see Govardhan and Margolin, 1995; Adams et al., 1995). Thus now it is possible to use enzymes in aqueous solutions containing water-miscible organic cosolvents, aqueous organic biphasic mixtures, and anhydrous organic solvents. Research has also uncovered microorganisms from a variety of unconventional habitats such as the biosphere and the depths of the oceans that have the unique ability to accomplish chemical transformations at extreme conditions covering a wide range of temperatures, pressures, and salt concentrations. Hence it seems almost certain that enzymes will play an increasingly important role in industrial organic synthesis.
Other Important (and Some Lesser Known) Strategies of Rate Enhancement
Authors: Doraiswamy L. K.
Published: November 2020

The literature contains examples of several strategies of rate enhancement not covered in the previous chapters. Many of these are essentially strategies for individual reactions with little general appeal. On the other hand, a few are very important, and several others combine two or more strategies. Of these, photochemical and micellar enhancements are as important as the strategies considered earlier in this part. However, in photochemical enhancement, recent studies have shown that the basis of scale-up used so far is questionable (Cassano et al., 1995), and designs based on newer concepts are still in their infancy. In micellar catalysis, despite the advances made, there are few industrial applications. As a result, these are included in this chapter on other strategies. Hydrotropes and supercritical fluids, although “old” with respect to other uses, are emerging as strong contenders for rate enhancement and ease of processing. Hence these two strategies are considered at some length in this chapter. Also included are the use of microwaves and several combinatorial strategies such as PTC with electrochemical, enzymatic, or sonochemical techniques; the use of supercritical fluids in similar combinations; enzymatic reactions in micelles; and PTC reactions in supercritical fluids or membrane reactors. Interaction of light with a chemical species can initiate or enhance a chemical reaction. Reactions of this type are known as photochemical reactions. Of the many distinctive features of photochemistry, the following is particularly noteworthy: in thermal excitation processes, all three forms of energy, electronic, transational, and rotational, are raised to higher levels. In contrast, photoexcitation raises only the electronic energy level which leads to higher selectivity, as exemplified by the photochlorination of the methyl group of toluene without any ring chlorination. Further, photochemical reactions are ecologically clean and require much less aggressive methods than conventional syntheses. Examples of reactions initiated or enhanced by light are many, and a small number are in industrial use, particularly in the production of halogenated hydrocarbons, alkane sulfates, and fine organic chemicals, including vitamins and fragrances. But the potential is enormous.
Pressure-Tuning Spectroscopy: A Tool for Investigating Molecular Interactions
Authors: Drickamer H. G.
Published: November 2020

Pressure-tuning spectroscopy is a powerful tool for investigating molecular interactions. These interactions may involve organic or inorganic materials in liquid, polymeric, or crystalline media. In this article we confine our attention to organic molecules, largely in dilute solution in polymers or liquids. We demonstrate the use of high-pressure luminescence to study the effect of the environment on π* →π, π* →n and charge-transfer excitations, as well as the interaction between singlet and triplet states. In addition, we provide tests of the energy gap law for non-radiative dissipation of excitation, the role of viscosity in luminescent efficiency, and the internal consistency of various means of predicting and correlating energy transfer. Over the past 40 years, it has been amply demonstrated that high pressure is a powerful tool for studying electronic phenomena in condensed phases. The basic concept is as follows. The optical, electrical, magnetic, and chemical properties—collectively the electronic properties—of condensed phases depend on the interactions of the outer electrons on the atoms, molecules, or ions that make up the phase. Different kinds of electronic orbitals have different spatial characteristics—different radial extent, different shape (orbital angular momentum), and different diffuseness; therefore, pressure perturbs the energies associated with these orbitals in different degrees. This relative perturbation we call “pressure tuning,” and the measurement and explanation of the tuning is “pressure-tuning spectroscopy.” Pressure-tuning spectroscopy of the vibrational and rotational excitations of atoms in molecular and in crystal lattices is also an active and important field, but in this article we arc concerned mainly with electronic phenomena. We further limit this discussion primarily to organic molecules in solid polymers or liquid solutions, as these have the greatest relevance to biologically active systems. A variety of probes are used for studying electronic phenomena under high pressure, but the emphasis here is on luminescence. The presentation consists of a series of examples of various types of excitations on interactions where high pressure has been an effective tool. Only references directly relevant to each example are included. Two general references to pressure studies of molecular luminescence have been published (Drickamer, 1982, 1990).
Temperature- and Pressure-Induced Unfolding of a Mutant of Staphylococcal Nuclease A
Authors: Eftink Maurice R. , Ramsay Glen D.
Published: November 2020

Nuclease conA is a hybrid version of Staphylococcal nuclease that contains a six amino acid (β-turn substitute from concanavalin A. This hybrid protein has a much lower thermodynamic stability than does the wild-type protein. This enables the unfolding of the protein to be achieved easily by several types of perturbations. From temperature-, pressure-, and denaturant-induced unfolding studies, we have found the free energy change for unfolding, ΔG°un, to be approximately 1.4 kcal mo−1 at pH 7, 0.1 M NaCI, and 20 °C, as compared to a thermodynamic stability of approximately 5.5–6 kcal mo−1 for wild-type nuclease A. Due to its reduced thermodynamic stability, nuclease conA also shows evidence of unfolding at low-temperature (cold denaturation), with a temperature of maximum stability of 13–15 °C. The thermal unfolding of nuclease conA is shown to be two-state by simultaneous measurement of fluorescence and CD changes as a function of temperature, using a modified AVIV CD instrument. Increased hydrostatic pressure unfolds nuclease conA in what appears to be a two-state manner, with an apparent of ΔV°un approximately —100 ml mol−1. From studies of the pressure (p)-induced unfolding of this hybrid protein as a function of temperature (T), we can define the complete p-T free energy surface for the unfolding transition. In auxiliary studies, we have characterized the fluorescence intensity decay and anisotropy decay of the single tryptophan residue (Trp-140) of nuclease conA in the native state and in the unfolded state induced by temperature, pressure, and denaturant. For each type of perturbation, there is a red shift in fluorescence, a lowering of the mean fluorescence lifetime, and a lowering of the rotational correlation time of the tryptophan residue to a value of ~1 ns (compared to 10–15 ns for the native state). The thermodynamics of the unfolding of proteins has received renewed interest in recent years, owing to the availability of a rich variety of mutant proteins and to advances in our understanding of their structural features. Among the questions being asked are, What are the relative energetic contributions of the hydrophobic effect and other interaction forces?
Application of Pressure Relaxation to the Study of Substrate Binding to Cytochrome P-450cam versus Temperature, Pressure, and Viscosity
Authors: Bon Hoa Gaston Hui , Di Primo Carmelo
Published: November 2020

The pressure-jump relaxation technique is a convenient and interesting means of studying rapid reversible reactions of biological systems. According to the change in reaction volume that accompanies a biochemical process, a rapid pressure change Δp produces a relative equilibrium shift ΔK/K, which is given by ΔlnK = AK/K = — (ΔV°/RT) Δp, where ΔV° is the reaction volume change. If the pressure change has a very short transition time, then relaxation kinetic measurements near equilibrium are possible, allowing the elucidation of reaction mechanisms through the detection of eventual reaction intermediates and the characterization of elementary kinetic and thermodynamic parameters. Our reversible pressure-jump method described in this chapter is capable of producing a sharp pressure change of ±20MPa in less than 3 milliseconds allowing the determination of relaxation rates in the time range of several milliseconds to several minutes at any final pressure up to 400 MPa, and in any viscosity solution. This technique was employed to study the binding kinetics of camphor and its analogues to bacterial cytochrome P-450cam as functions of temperature, pressure, and viscosity. The results obtained are discussed in terms of conformational dynamics of the protein associated with the entry and the exist of water molecules and specific interactions of the substrate1 with the apolar residues in the active site of cytochrome P-450cam. The binding of ligands or substrates to proteins can exhibit multistate kinetic behavior similar to transient-stale enzyme kinetics and isomerizations of proteins. The underlying elementary reaction mechanisms can be elucidated by the use of rapid mixing techniques. Usually a reaction is initiated by mixing the reactants as rapidly as possible, and the approach to equilibrium is monitored. This method has been adapted to the study of enzyme reaction mechanisms under extreme conditions of temperature and pressure (Hui Bon Hoa & Douzou, 1973; Balny et al., 1984). However, this approach is limited by the deadtime, the large amount of sample required, and difficulties in using the apparatus to study viscous solutions, such as Schlieren effects, caused by incomplete mixing in flow experiments. Relaxation techniques overcome these problems by the application of a physical perturbation to a system already at equilibrium.
Osmotic and Hydrostatic Pressure as Tools to Study Molecular Recognition
Authors: Sligar Stephen G. , Robinson Clifford R.
Published: November 2020

The question of molecular recognition is a central paradigm of molecular biology, playing central roles in most, if not all, cellular processes. Failed recognition events have been implicated in numerous disease states, ranging from flawed control of gene regulation and cellular proliferation to defects in specific metabolic activities. Historically, questions of molecular recognition have been approached through organic synthesis and through actual structural studies of biomolecular complexes. Fundamental insight into the mechanisms of molecular recognition can be realized through the use of broad interdisciplinary tools and techniques. In particular, the use of recombinant DNA technology in concert with hydrostatic and osmotic pressure methodologies have proven to be ideal for understanding the fundamental mechanisms of recognition. In our presentation, we will focus on recent results from our laboratory that examine three major classes of recognition events in biological systems: 1. Protein-protein recognition: here we seek to define the role of specific surface interactions; electrostatic, hydrogen bonding, and hydrophobic free energies provided through surface complimentarity, which define the specificity and affinity in the formation of complexes between the metalloproteins involved in electron transfer events in cytochrome P-450-dependent oxygenase catalysis and in the assembly of tetrameric hemoglobin. 2. Protein—small molecule recognition: here we seek to ascertain how the same fundamental forces of electrostatics, hydrogen bonding, and the hand-glove fit of a substrate into the active site of an enzyme can give rise to the observed high degree of control of regio- and stereo-specificity in catalysis and in the interfadal interactions of proteins at electrode interfaces. 3. Protein nucleic acid recognition: here again the same fundamental forces control recognition processes, but in this case we will focus on our exciting, recent discovery of a role for solvent water in mediating recognition between protein and nucleic acid components. Representative systems in the binding/ catalytic class of restriction endonucleases and recombinases will be discussed. In all cases, the use of pressure as a variable has provided unique understanding for the molecular details of these processes. Pressure, both hydrostatic and osmotic, has proven to be an enabling experimental technique in understanding the mechanistic origins of molecular recognition events.
Introduction Nuclear Magnetic Resonance Spectroscopy: Basic Theory and Background
Authors: Knicker Heike , Nanny Mark A.
Published: November 2020

Nuclear magnetic resonance (NMR) spectroscopy is one of the most powerful experimental methods available for atomic and molecular level structure elucidation. It is a powerful technique in that it is a noninvasive probe that can be used to identify individual compounds, aid in determining structures of large macromolecules, such as proteins, and examine the kinetics of certain reactions. NMR spectroscopy takes advantage of the magnetic properties of the observed nucleus that are influenced not only by its chemical environment, but also by physical interactions with its environment. Both can be examined by measuring specific NMR parameters such as coupling constants, relaxation times, or changes in chemical shifts. As NMR techniques and instrumentation advance, NMR spectroscopy is becoming more important in the environmental sciences, tackling problems and questions that previously were difficult to answer. For example, sensitivity enhancement techniques increase the ability to examine a sample without chemical or physical pretreatment. A sample examined in this manner is in its original state and is unaffected by chemical or physical reactions caused by the pretreatment procedure. Despite its increasing popularity and numerous advantages, NMR spectroscopy can be a mysterious, and at times daunting, technique. The purpose of this chapter is to provide an overview of basic NMR theory and background for the uninitiated. It is hoped that it will provide enough information to those unfamiliar with NMR and its terminology for them to find the remaining chapters understandable and interesting. Those who desire a greater understanding are referred to the many textbooks on solution-state NMR, solid-state NMR, and the application of NMR to geochemistry, soil chemistry, oils and coals, and carbonaceous solids. The advance that led to NMR spectroscopy came in 1939 with resonance experiments by Rabi and coworkers, who demonstrated the property of nuclear spin. In 1945, the research groups of Bloch and Purcell independently obtained the first nuclear resonance signals. For this they won the 1952 Nobel prize. The first application of NMR spectroscopy in the field of humic substance research was 1H NMR of liquids. González-Vila et al. were the first to apply 13C solution-state NMR to natural humic acids.
Sorption Processes in the Environment: Nuclear Magnetic Resonance Spectroscopy as a New Analytical Method
Authors: Nanny Mark A.
Published: November 2020

The transport and fate of chemicals in the environment comprise one of the most pertinent issues in environmental chemistry. Physical and chemical interactions between the chemical of interest (sorbate) and the various components present in soil, water, and sediment (sorbent) can dramatically influence the transport and fate of the chemical. For example, organic material such as humic acids or surfactants, when bound to the surface of soil, sediment, and clay particles, can enhance sorption of chemicals to the particle surface, immobilizing the chemicals and possibly protecting them from degradation. The term “sorption,” as used in this chapter, refers to any physical or chemical association between the sorbate and sorbent. Thus, this definition includes molecular associations ranging from hydrophobic partitioning processes to covalent binding. It has also been observed that sorbents can act as a “buffer system” for the sorbate by taking up the sorbate when it is present at high concentrations and then slowly releasing it back into solution during periods of low or zero sorbate concentration. This type of behavior is important when the environmental presence of the chemical is episodic, such as in seasonal application of pesticides and herbicides. A dramatic example of this is presented by Steinberg et al., who detected the volatile, soil fumigant 1,2-dibromoethane in agricultural topsoils up to 19 years after the last application. On the other hand, soluble organic matter such as dissolved humic and fulvic acids can dramatically increase the apparent solubility of many hydrophobic chemicals in soil and sediment pore water. In this manner, the mobility of the chemical is increased. Thus, the nature and presence of organic material can strongly influence the transport properties of many chemicals in the environment. It is well known that sorption processes are a function of numerous parameters: the chemical characteristics of the sorbate (e.g., hydrophobicity, polarity), and the identity and chemical characteristics of the mineral phase and its organic coating. Other parameters important to sorption processes are the porosity of the sorbent particles, the presence of dissolved organic matter, and the solution pH and ionic strength.
A New Teacher Learning to Share Responsibility with Parents
Authors: Steele Karen
Published: November 2020

When I enrolled my son in the OC, the aspect that most excited me was the opportunity for my husband and me to be involved in his educational life; we had a view of education that incorporated the family as an integral part of the learning experience. When a job opened up for a kindergarten teacher in the OC the next year, I was eager to apply. I espoused the philosophy of the OC and saw teaching in the OC as a way to try new things that I had not been able to in my eight years as a special education teacher. I knew that I would love teaching in a program with this degree of parental involvement. My experience as a parent in the OC made me feel that I had a good grasp of the logistics of including parents and how they would work in my classroom. I had not realized how much my training as a teacher in a traditionally organized classroom would affect my ability to truly integrate a different philosophy of teaching and to work with parents in my classroom on such a regular basis. The expectation of how my classroom should run stemmed from my traditional training, which led me to believe that the teacher should be completely in control of what happens in the classroom. I began my new teaching position with a mixture of enthusiasm and trepidation. I would have the parents of my students there watching my every move! As I began to learn how to adapt to this scary thought, it became clear to me that I had not anticipated the amount of adult interaction that would occur on a daily basis. The suggestions, encouragement, decisions, criticism, complaints, and praises that are a natural part of teaching suddenly occurred on a scale that I had never experienced before. As the kindergarten teacher, I found it especially hard because many of the parents were new to the OC as well as new to kindergarten. They were learning how to be effective in the classroom as well as feeling anxious about how their young children were getting along in their first school experience.
Some Thoughts on Curriculum and Change
Authors: Botstein Leon
Published: November 2020

It should go without saying that in the twentieth-century history of American higher education, each significant curricular reform movement has had a distinct political agenda. This is particularly true for initiatives designed to create decisive changes in the shape of the undergraduate curriculum. In those circumstances in which a political movement and an institutional initiative have coincided, a distinct political purpose can be discerned in what the institution required of its students and how the program was articulated. The historical moment was certainly at issue in the case of the reforms of the 1930s. Men such as Robert Hutchins, Stringfellow Barr, and Scott Buchanan saw in the idea of a core curriculum a way to realize their ideal construct of democracy. The Great Books concept and the variants of the core at Chicago had at their root a notion of natural rights and the social contract. Inherent in that framing of the body politic were concepts of freedom and civic responsibility. The objective was clear: one needed to educate young Americans—the elite of the nation—to steer the country away from the extremes of fascism and communism. Radical reform was imperative, since during the Great Depression both of these alternatives appeared politically viable. In the post-World War II era, the Cold War framed most of the discussion about the curriculum. This claim may seem odd, but on closer inspection, beginning with Harvard's general education reform from the early 1950s, the concept of the university, until the late 1980s, was substantially defined by a consciousness of how much the United States constituted an alternative to political unfreedom. The elective-course system in its new Harvard form, combined with distribution requirements and an enormous premium on undergraduate specialization, was a kind of metaphorical mirror of the idealized free marketplace of ideas. We were convinced that we were training young people to cherish the advantages of free choice and liberty in a world in which the grim alternative of totalitarianism was not a mirage but a present danger.
Technology and Computer Literacy
Authors: Lyman Peter
Published: November 2020

What is "computer literacy," and what is its place in liberal education? Liberal education is incomplete if it does not prepare educated people to address the presence of technology and, more important, the presence of technology's information products, in an informed and critical way. There are four reasons I say this. First, the traditional liberal arts understanding of technology as machine, merely an "object" in relation to human "subjectivity," is an essentially aristocratic attitude that fails to acknowledge the way technology and information saturate the modern world in which educated people live and work. Second, defining the computer as a mere machine is an uncritical ideology that enhances the technological mythology that computers are more objective than humans, thereby masking and legitimating the social power of technicians. But, third, there is a deeper reason as well: technical objects are created within a technical culture that contains a powerful (if tacit) critique of liberal education, one that has the potential to replace liberal education in the modern world. Finally, liberal education's dismissal of computers as mere machines distracts attention from the fact that technology's information products define modernity: mass communications mediate most of the information in our culture, and digital technology produces the images and information that saturate everyday life. If liberal education is to come to terms with the significance of technology in the modern world, or to subject technology-mediated communication and information products to critique, liberal education must also become self-reflective about the technical objects that shape its own communications and information. What is the origin of the book form, as it has evolved from the codex, the journal, and the social organization of education around printed objects (the bookstore, the lecture, the library, the disciplinary society, scholarly publishers, the college)? What are the origins of the concept of creativity stemming from individual genius, and of the social construction of the "author" as property right holder? In some ways, higher education is the last social institution primarily organized around print technology and still resistant to information technology.
Charge Density Studies of Transition Metal Compounds
Authors: Coppens Philip
Published: November 2020

The electron density in transition metal complexes is of unusual interest. The chemistry of transition metal compounds is of relevance for catalysis, for solid-state properties, and for a large number of key biological processes. The importance of transition-metal-based materials needs no further mention after the discovery of the high-Tc superconducting cuprates, the properties of which depend critically on the electronic structure in the CuO2 planes. The results of theoretical calculations of systems with a large number of electrons can be ambiguous because of the approximations involved and the frequent occurrence of low-lying excited states. The X-ray charge densities provide independent evidence from a technique with very different strengths and weaknesses, and thus can make significant contributions to our understanding of the properties of transition-metal-containing molecules and solids. In inorganic and organometallic solids, the average electron concentration tends to be high. This means that absorption and extinction effects can be severe, and that the use of hard radiation and very small crystals is frequently essential. Needless to say that the advent of synchrotron radiation has been most helpful in this respect. The weaker contribution of valence electrons compared with the scattering of first-row-atom-only solids implies that great care must be taken during data collection in order to obtain reliable information on the valence electron distribution. When the field exerted by the atomic environment is not spherically symmetric, as is the case in any crystal, the degeneracy of the d-electron orbitals is lifted. In the electrostatic crystal field theory, originally developed by Bethe (1929) and Van Vleck (1932), all interactions between the transition metal atom and its ligands are treated electrostatically, and covalent bonding is neglected. Since the ligands are almost always negatively charged, electrons in orbitals pointing towards the ligands are repelled more strongly, and the corresponding orbitals will be higher in energy. The discussion is the simplest for the one d-electron case, in which d-d electron repulsions are absent.
The Intellectual Context
Authors: Gleason Philip
Published: November 2020

Central to the intellectual revival that dominated Catholic higher education between World War I and the Second Vatican Council was the recovery of Scholastic philosophy and theology, particularly that of St. Thomas Aquinas. The “Scholastic Revival,” as it was called, began in the middle decades of the nineteenth century and was officially endorsed by Pope Leo XIII in 1879. Although its influence was felt earlier, especially in seminaries, it did not affect American Catholic higher education in a really pervasive way until the 1920s. By the end of that decade, however, Neoscholasticism had become a “school philosophy” that served for Catholic colleges very much the same functions that Scottish common sense philosophy and Baconianism served for Protestant colleges in the first half of the nineteenth century. To understand how this came about, we must review the earlier phases of the revival and highlight the main features of Neoscholasticism as a system of thought, before attempting to link its popularization with other events and movements of the 1920s. The term Scholasticism refers broadly to the teaching and method of the “schoolmen,” that is, the philosophers and theologians who propounded their views at the medieval universities, especially at the University of Paris. St. Thomas Aquinas (1225-74) is generally regarded as the outstanding figure among the Scholastics, and the revival of the nineteenth century aimed primarily at recovering his ideas and drawing upon them to establish Catholic teaching on a solid intellectual foundation. This effort involved a process of gradual clarification because the full richness of Thomas’s thought emerged only in the course of the historical investigations set off by the revival. The same is true of its relation to the thinking of other schoolmen and of later commentators, especially post-Reformation Scholastics like the Spanish Jesuit Francisco Suarez, who died in 1617. The virtually interchangeable use of the terms “Neothomism” and “Neoscholasticism” reflected the ambiguity that persisted well into the twentieth century as to the precise relationship between the thought of St. Thomas himself and that of the larger school of which he was the acknowledged master.
Institutional Developments: Moving into Graduate Work
Authors: Gleason Philip
Published: November 2020

At the same time Catholic educators were espousing and attempting to put into practice the countercultural intellectual position described in the previous chapters, they continued to modernize their schools in organizational terms. Conservatives warned that accepting the new organizational trends paved the way for secularization, but the experience of the first two decades of the century proved that Catholic institutions could not survive unless they adjusted themselves to prevailing norms. Rigid adherence to the old ways meant extinction. So despite the uneasiness they sometimes felt about what they were doing, most Catholic educators believed that they could modernize their educational structures and practices without compromising their religious distinctiveness. Indeed, the more forward-looking insisted that this kind of organizational reform was essential if the Catholic worldview was to be effectively presented to students and adequately represented in the larger world of learning. The growth of Catholic higher education between 1920 and 1950 seemed to vindicate this line of thinking. Sheer growth was, in fact, the most obvious institutional development of these years. The actual numbers are hard to establish because of differences over time in the way institutions were classified and enrollments recorded. However, the statistics gathered by the National Catholic Welfare Conference provide a reliable indication of overall trends. The table below sets forth the basic data by ten-year intervals from 1920 to 1950, along with comparative figures for all institutions of higher education in the country. These statistics indicate that over a three-decade span of fabulous growth the Catholic sector of American higher education maintained a pretty consistent proportion of national totals in respect to numbers of institutions and faculty members. In terms of enrollment, Catholic schools almost doubled their percentage share of the national total, even with students attending seminaries and strictly teacher-training institutions being excluded from the count. Closer analysis reveals that, although observers at the time spoke of the post-World War II surge in enrollments as unprecedented, the Catholic growth rate of the 1920s far outstripped that of the 1940s.
Public Buildings
Authors: Sperber Daniel
Published: November 2020

Around the central market forum area, every Roman town with pride and pretensions to importance developed a number of public buildings that made up a standard set, the components of which we can glean not only from the remains themselves but also from Vitruvius’ architectural treatise. In Book 5 he sets out “the arrangement of public places” (publicorum locorum dispositiones), listing almost exactly the buildings to be found in any Greek and Roman city: forum, basilica, treasury, prison and councilhouse, theater with adjoining porticoes, baths, palaestra, and harbor and shipyards. We have already discussed the prominent nature of the bathhouse, the palaestra is specifically admitted by Vitruvius not to be a usual thing in Italy, and harbors and shipyards are obviously dependent on specific geographic location. Of the other buildings, the treasury and prison, although necessary, were probably of minor importance and therefore do not merit much attention in the sources, while the council and senate-houses are expected features in a society in which a self administering community was the standard form of political life. The one building that stands out as peculiarly Roman is the basilica, a large covered hall that performed the functions of the ubiquitous stoas of Hellenistic architecture, and is obviously loosely related to them, but had a form that appears to lack any clear parallel in the Greek world. We shall discuss and describe some of these focal points of the urban center, beginning with the most prominent, the basilica. The basilica is often identified with the courts of justice. However, this identification is by no means clear. Indeed, it served either as a court of law and seat of the magistracy or as a place of meeting for merchants and men of business. These two uses were so mixed that it is not always easy to state which was the principal. The basilica at Fanum, of which Vitruvius was the architect (5.1.6-10), was entirely devoted to business, and the courts were held in a small building attached to it—the temple of Augustus. In Pompeii the basilica was situated next to the public granaries (horrea), indicating its commercial functions.
The Great Comet Crash of 1994
Authors: Verschuur Gerrit L.
Published: November 2020

Just as everyone offering odds was beginning to feel secure that comet impact is not an immediate threat to life on earth, I heard several planetary scientists state confidently that there was not even a chance of our seeing a comet-planet collision in our lifetimes. Since then Jupiter suffered the humiliation of being lashed by no less than 21 comet fragments, most of them sizable objects in their own right. The saga began on March 24, 1993, when Carolyn Shoemaker discovered a “squashed comet” in a photograph that had just been taken by the team of which she was a member. She and her husband, Eugene, together with David Levy were using the 18-inch Schmidt telescope on Palomar Mountain near San Diego to hunt for near-earth asteroids and none of them had ever seen a squashed comet before. What happened to set the scene for the discovery of the squashed comet is now apocryphal. The previous night had been perfect for the search, but someone had apparently exposed a box of film to daylight so that the exposures turned out totally black. The box of film was set aside, which was no immediate loss because on the fateful night the skies were mostly cloudy, which made comet hunting very difficult. Apparently David Levy, not wont to waste any opportunity to take more pictures, suggested that they go ahead and use some of the ruined sheets of film just in case some were not totally useless. At a cost of $4 per sheet, the film was usually very carefully used, given that they took photographs every ten minutes or so, all night long. Normally they would not have taken data that night, but why not go ahead and fire off a few exposures with the bad film. between and through the clouds. As luck would have it, the sheets of film deeper into the box were only light-damaged around their edges, so they managed to get some nice photographs. It was Carolyn Shoemaker’s task to place a pair of developed pictures taken 45 minutes apart of the same area of sky into a stereo microscope.
Finding Secrets: Inference
Authors: Wiener Harvey S.
Published: November 2020

A colleague arrives at work one Monday morning at 9:30. She's usually there at 8:00 A.M., ahead of everyone else. She mumbles under her breath and shakes her head from side to side, biting her lip. She doesn't say "Hello" as she usually does, but instead, staring straight ahead, she storms past your desk. At her office she turns the knob roughly, throws open the door, and then slams it loudly behind her. What's going on here? This is a classic bad mood scene, isn't it? No direct evidence, of course—your colleague doesn't say anything to you—but you can add up the pieces to figure out some important information for yourself. Clearly, she's angry or upset about something. To reach that judgment, you relied on what you saw and heard at the moment, but also on what you know about her usual behavior. No one had to tell you that she was furious. From her appearance, her actions, her body language, and her behavior, it was safe to infer that something irritated her. You were assessing the scene, and your natural ability to draw inferences fed you information that you needed in order to figure out her behavior. What is inference? When we infer, we derive information by a complex process of reasoning that balances assumptions, induction and deduction, instinct, prior experience, perception, hunches—even, some believe, ESP. Many people define inference as reading between the lines. This definition, of course, is figurative. It says that being able to determine information in this way is like figuring out hidden meanings—beyond the apparent ideas expressed by words and sentences. More information resides on a page of text than what the lines of print say. You can tell from this familiar metaphor—reading between the lines—that inference is usually intertwined with the reading process. In other words, we conceive of the act of inference as print-bound. Much of the essential meaning from a page does come to us as cues and clues in a writer's discourse.
Communities and Habitats
Authors: Moll Don , Moll Edward O.
Published: November 2020

Rivers are dynamic and diverse ecosystems composed of a variety of habitats including the main channel, side channel, flood plain and backwater lakes as discussed briefly in chapter 2. Each habitat typically contains a characteristic assemblage of turtles (herein considered synonymous with a chelonian community). Although riverine chelonians may appear anywhere in the river, most species specialize in one or more habitats where they occur in maximum numbers and biomass. Thus, the various habitats of the river may have similar species composition but the rank abundance for each species will differ. Basic divisions of typical rivers are lotic (flowing water) habitats and the lentic (still water) habitats. Beyond this, habitat divisions involve such physical features as gradient (headwaters versus lower reaches), substrate (sand, gravel, and mud), size (feeder streams versus the river proper), shoreline heterogeneity (wooded, marsh, swamp, etc.) and even temperature. One can expect differences in species composition associated with any of these habitat features. The composition of river turtle communities is affected by the biotic as well as the physical environment of the stream. The presence or absence of lower and higher plants, competing species, or predators can all affect community composition. This chapter is chiefly concerned with assemblages of species rather than the individual species comprising these groups. It will examine the composition of river turtle communities, their ecology, and their evolution. The concept that organisms occur in assemblages of species interacting to produce distinctive community characteristics was neglected for many years in the herpetological literature. Prior to the mid-1960s, most ecological research on reptiles was autecological (Scott, 1982). Nevertheless, a scattering of early papers described chelonian assemblages associated with particular habitats. Evermann and Clark’s biological survey of Lake Maxinkuckee in 1920 included an overview of the turtle community. In 1942, Fred Cagle delineated the species composition and relative abundance of turtles inhabiting six lentic habitats in southern Illinois. In 1950 he published a similar report with A. H. Chaney on ten lentic and two lotic habitats in Louisiana. Tinkle (1959) compared the species composition and relative abundance of species above and below the “fall line” in five United States rivers emptying into the Gulf of Mexico.
Linearizing Voltage-Dependent Currents
Authors: Koch Christof
Published: November 2020

We hinted several times at the fact that a small excitatory synaptic input in the presence of voltage-dependent channels will lead to a local depolarization, followed by a hyperpolarization. Those of us who built our own radios will recognize such an overshooting response as being indicative of so-called RLC circuits which include resistances, capacitances as well as inductances. As a reminder, a linear inductance is defined as a circuit element whose instantaneous I—V relationship is, where L is the inductance measured in units of henry (abbreviated as H). Although neurobiology does not possess any coils or coillike elements whose voltage is proportional to the current change, membranes with certain types of voltage- and time-dependent conductances can behave as (/they contained inductances. We talk of a phenomenological inductance, a phenomenon first described by Cole (1941) and Cole and Baker (1941) in the squid axon (see Cole, 1972). Under certain circumstances, discussed further below, such damped oscillations can become quite prominent. This behavior can be obtained in an entirely linear system, as can be observed when reducing (in numerical simulations) the amplitude of the synaptic input (or step current): even though the voltage excursion around steady-state becomes smaller and smaller, the overshoot persists. It is not due to any amplification inherent in such a membrane but is caused by its time- and voltage-dependent nature. Such a linear membrane, whose constitutive elements do not depend on either voltage or time, and which behaves like a bandpass element, has been called quasi-active (Koch, 1984) to distinguish it from a truly active, that is, nonlinear membrane. In this chapter, we will explain in considerable detail how an inductance-like behavior can arise from these membranes by linearizing the Hodgkin-Huxley equations. Experimentally, this can be done by considering the small-signal response of the squid giant axon and comparing it against the theoretical predicted value, a further test of the veracity of the Hodgkin-Huxley equations, which they passed with flying colors.