bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular replacement
Authors: Fitzgerald P M D 
Published: November 2023

Abstract
This paper will discuss the theory, implementation, and limitations of the computations used in phasing crystal structures using the molecular replacement method. It will describe the rotation function, the various positioning techniques (translation function, correlation searches, and packing analysis), and the methods used to improve upon a molecular replacement solution prior to refinement Means for evaluating the correctness of a solution will be discussed and some illustrative examples of structures phased by molecular replacement will be given. Finally, some recent work in developing a methodology for using the rotation function to find erroneous regions in a molecular replacement probe structure will be presented.
Introduction to macromolecular refinement
Authors: Sussman J 
Published: November 2023

Abstract
‘Three-dimensional macromolecular models based on X-ray diffraction data are derived initially from electron density maps. The atomic coordinates based on such models are not very accurate, in part because the maps are of insufficient resolution to show the constituent atoms individually and in part because the phases used to calculate the electron densities are not very accurate. Even for models derived from the best electron density maps, the accuracy of the atomic coordinates is likely to be no better than about 0.5 Å, and localized regions of models derived from average quality maps may suffer more serious errors. Such models, however, are very useful in showing the overall features of macromolecules and the pattern of chain folding but to understand much of the chemistry of these molecules and how they function requires more accurate parameters. It is important, therefore, to improve the models of macromolecules by refining them to the fullest extent possible.’
Time-averaged crystallographically restrained molecular dynamics
Authors: Gros P 
Published: November 2023

Abstract
A number of reports have appeared in the literature to account for mobility and disorder in macromolecular crystals. Schomaker & Trueblood (1968) showed that, to a first approximation, the atomic temperature factors can be related to the overall mobility of the molecule. It is, therefore, possible to refine the six overall anisotropic B-factors of the whole molecule (Sheriff & Hendrickson, 1987). More atomic detail is taken into account in the restraints on individual temperature factors of neighbouring atoms (Hendrickson & Konnert, 1980). This procedure is based on the riding-motion model of Busing & Levy (1964). Furthermore, Konnert & Hendrickson (1980) propose a procedure to refine atomic anisotropic temperature factors based on the stereochemistry of the model. Yu et al. (1985) show that the assumption underlying this method, i.e. a simplified correlation between the stereochemistry of the model and the atomic fluctuations, is invalid. Another approach is described by Haneef et al. (1985). Segments, like ring systems of Phe and Tyr, are treated as rigid groups, of which B-factors are refined anisotropically (Howlin et al., 1989 ). Very recently Kidera & Go (1990) have proposed an elegant method that treats the anisotropy of the atomic distributions of the molecule in the crystal by a normal mode refinement. In all these procedures the anisotropy is treated in a restricted way to reduce the number of parameters, and no general treatment is given for anharmonicity.
Applications of silicon and tin in borane chemistry
Authors: Brown* Herbert C , Rangaishenvi Milind V 
Published: November 2023

Abstract
In 1956 it was discovered that the simplest hydrogen compound of boron, B H, diborane, adds with remarkable ease to unsaturated organic compounds. The products are organoboranes. Investigation of these organoboranes revealed that they have a rich chemistry, greatly facilitating the synthesis of a vast host of organic compounds. The substitution reactions of organoboranes reveal a unique feature. They proceed with complete retention of structure and configuration.
Organotin halides as catalytic precursors in dehydration processes.:I.Acetalizations and transacetalizationsof alicyclic diols and polyols
Authors: Marton Daniele , Slaviero Pierangelo , Tagliavin Giuseppe , Vanzan, Nicoletta , Zordan Michele 
Published: November 2023

Abstract
Butyltin trichloride can be used with advantage as a catalyst for the preparation of cyclic acctals from aldehydes and diols, or polyols under mild conditions and with short reaction times. Many 1,3-dioxolanes and-dioxanes can be prepared via acetalization and transacetalization processes. The initial stages of the reaction involve either (i) activation of the aldehyde via formation of RCHO-SnBuCJ, followed by its interaction with the diol, or (ii) formation of the organo-alkoxytin dichloride HO― (CH),, ―O―SnBuCl (n = 2,3), which is followed by the insertion of the aldehyde into the Sn―O bond.
How silicon and tin meet in polymer and organic synthesis
Authors: Gauron V , Jousseaume B , Verlhac, M Pereyre J -B , Frances J -M 
Published: November 2023

Abstract
The organic chemistry of silicon and tin has gained much significance in recent years on both academic and industrial grounds. At Bordeaux, we have been involved in research where both silicon and tin have featured synergistically. Two examples are presented in this paper. The first topic deals with polymer science and describes the preparation and the applications of new latent organotin catalysts for the reticulation of polyorganosiloxane chains (SiOH/SiOR and SiOH/SiH polycondensations). The underlying principle is to use bis(2-acyloxyalkyl)diorganotins, which are themselves not catalysts, but which are thermally degraded through a J3-elimination process into diorganotin dicarboxylates, an important class of commercial catalysts.
Organotin xanthylacetates: 119mSn Mossbauer and in vitro fungitoxicity study
Authors: Weng Ng Seik , Kuthubutheen A J , Arifin, Zainudin , Das V G Kumar 
Published: November 2023

Abstract
In studies on the biological properties of triorganotin compounds, it has been widely held that toxicity is dominantly governed by the nature of the three C-bonded organic groups on tin, with only marginal influence being ascribed to the anionic group through properties such as solubility and volatility. However, recent studies on triaryltin systems possessing a wider selection of anionic groups have indicated that rather significant influences on overall toxicity can be exerted by the noncarbon-bound residues.
Microwave plasma chemical vapour deposition: a model for the production of thin carbon films, with possible extension to silicon
Authors: Barmawi Khairurrijal M 
Published: November 2023

Abstract
A simple plasma CVD reactor has been built using a 500 W, 2.45 GHz microwave oven as a plasma generator. The reactor has been used to deposit carbon from liquid natural gas onto glass plates. The rate of deposition is 34 As-1 and films typically of 6 |xm thickness can be conveniently obtained. The carbon films have been analysed by FT-IR spectroscopy and found to contain sp, sp2, and sp3 hybridized carbon fragments; there are also indications of the presence of C=O and C=S groups. The reactor offers much scope for similar studies on thin silicon films.
Communication in the physical sciences
Authors: Laidler Keith J 
Published: November 2023

Abstract
Progress in the sciences is closely linked to the manner in which scientists communicate with each other and with the general public. Over the years there have been important changes in the extent to which different kinds of communication have been used. In earlier times scientists tended to be secretive about their work, but were faced with the dilemma of not being able to claim priority for a discovery if anyone else announced it later. Newton was involved in a number of difficulties of this kind, and often became engaged in acrimonious controversy. One way around the dilemma was to summarize a discovery in the form of an anagram so complicated that it could only be deciphered by the author himself. In its early days the Royal Society was a repository for anagrams. Much of the communication of early science was in the form of personal letters. Robert Boyle, for example, described many of his experiments in the form of letters to friends and relatives, often publishing them later as pamphlets. He also communicated many of his findings orally to the numerous visitors to his laboratories in Oxford and London. Even later the same kind of informal communication was still used to some extent. In the nineteenth century Maxwell, Kelvin and P. G. Tait were frequent correspondents on matters relating to thermodynamics and the kinetic theory. Very little of Max¬ well’s important work on thermodynamics, including his ‘Maxwell demon’, was published in a formal way, and our knowledge of much of it has come to us indirectly from the many private letters (and often postcards!) he wrote, and from his university lectures.
Solutions Of The Boltzmann Equation
Authors: Mccourt Frederick R W , Beenakker Jan J M , Köhler Walter E , Kuščer Ivan 
Published: November 2023

Abstract
It often happens in theoretical physics that equations are much easier to derive than to solve. Such is certainly the fate of the nonlinear Boltzmann equation for which, after more than a hundred years, the equilibrium solution is still the only known exact solution of general validity. Fortunately, this has not hindered anyone from attempting to obtain solutions numerically via step-by-step integration in time, starting with given initial conditions. In view of the many variables involved, any such task is formidable even for modern computers. Stationary solutions are even harder to find. If general physical insight is sought, we still require approximations based upon simplifying assumptions.
Spectroscopic Phenomena
Authors: Mccourt Frederick R W , Beenakker Jan J M , Köhler Walter E , Kuščer Ivan 
Published: November 2023

Abstract
Radio-frequency radiation can be used to probe the relaxation of macroscopic nuclear magnetizations in a gas, which occurs either directly via the effect of collisions on individual nuclear spins (as in a monatomic gas) or indirectly via collisional reorientation of the molecular rotational angular momentum (which is weakly coupled to the nuclear spins). As described in § 11.1, nuclear spin relaxation provides a sensitive probe of intermolecular interactions, but it is a difficult experiment to carry out and it does require the presence of a nuclide having non-zero spin. Information obtained from nuclear spin relaxation studies is in many cases complementary to that obtained from depolarized Rayleigh light scattering measurements.
Introduction
Authors: Koningsveld R , Stockmayer W H , Nies E 
Published: November 2023

Abstract
As already emphasized in the Preface, phase transformations play a very important role in polymer science and engineering. Phase separation is the essential feature of classical as well as some modern methods of polymer fractionation, such as temperature-rising elution fractionation of partially crystalline polymers. Another example is presented by the fractionation of copolymers with respect to both chain length and chemical composition. Demixing may further have appreciable effects during polymerization, blending, and compounding processes. Partially crystalline polymers owe their stiffness and strength to regions of crystalline order. Phase behaviour determines the morphology of the material to a considerable extent, so that mechanical properties of polymer blends, block copolymers, and composites are found to be enormously dependent on phase relationships. Partial miscibility also plays important roles in biology and medicine, as for example in the formation of cataracts in eye lenses, protein separations, and fibril formation related to Alzheimer’s disease.
Interactions
Authors: Bruch L W , Cole Milton W , Zaremba Eugene 
Published: November 2023

Abstract
The properties of adsorbed layers are ultimately determined by the interactions among the constituents. These interactions are fundamental to a broad range of adsorption phenomena, including the equilibrium structures of the adsorbate, the phases that exist as a function of temperature and density, and surface kinetics. In this chapter, we develop the concepts that are central to understanding the forces acting in physical adsorption and review the progress that has been made in determining these forces from a priori theories or from semiempirical and empirical constructions using experimental data. Monographs on intermolecular forces include the books of Margenau and Kestner (1971), Mahanty and Ninham (1976), Israelachvili (1992), Stone (1996), and of Hirschfelder, Curtiss, and Bird (1964). Reviews of the forces in physical adsorption include Nicholson and Parsonage (1982), Bruch (1983a), Vidali et al.(1991), and Steele (1993).
Monolayer Films: Theoretical Context
Authors: Bruch L W , Cole Milton W , Zaremba Eugene 
Published: November 2023

Abstract
The development of scientific concepts usually proceeds from the simple to the complex. We now follow such a route in presenting the theory of monolayer adsorption. This chapter provides an introduction to the theory; Chapters 5 and 6 provide a more detailed description of the theory and a discussion of illustrative examples of film behavior, respectively. Three principal lines of conceptual development have strongly influenced the goals of theoretical efforts for monolayers and also have set a context in which most of the experiments have been analyzed.
Challenges in Synthetic Organic Chemistry
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
This book gives a much-needed account of the work of one of Japan's most important synthetic organic chemists, Teruaki Mukaiyama, providing an insight into his approach to synthetic problems and the development of new synthetic methods. Early chapters record research into a wide range of reactions, including dehydration reactions, the use of organosulfur compounds, and oxidation-reduction condensations in peptide and nucleotide synthesis. The second part of the book looks at the development of novel synthetic reagents, and includes an account of Mukaiyama's important work on the applications of titanium compounds in organic synthesis. Synthetic control is covered in the final chapters. All those working in organic synthesis will find this book of interest. It makes accessible much work which has hitherto been available only in the Japanese literature, and provides a unique account of the work of one of the world's leading synthetic organic chemists.
Chemical Oscillations and Instabilities
Authors: Gray Peter , Scott Stephen K 
Published: November 2023

Abstract
Scientists in many fields are now expressing considerable interest in non-linearity and the ideas of oscillations and chaos. Chemical reactions provide perfect examples of these phenomena since oscillating reactions, explosions, ignition, travelling waves, patterns, quasiperiodicity, and chaos are all features of chemical kinetics. This book introduces non-linear phenomena in chemical kinetics using simple model schemes. These models involve chemical feedback, such as chain branching, autocatalysis, and self-heating. The emphasis is on physical and pictorial representation, and on identifying those gross features which are essential. The experimental conditions under which such behaviour will occur can be predicted using simple mathematical recipes, and these are also included. The first part of the book begins with a discussion of long-lived oscillations for autocatalytic or exothermic reactions in closed vessels. Stationary states, bistability, and oscillations in continuous flow reactors and diffusion cells are then considered. This is followed by chemical wave propagation and by pattern selection and formation. Heterogeneous reactions are discussed, as they can also exhibit bistability and oscillations. Complex oscillations, quasiperiodicity, and chemical chaos, either forced or spontaneous, are introduced. Part 2 deals with real experimental systems, describing observed experimental behaviour and its interpretation in terms of the underlying chemical mechanisms or simplified models. The Belousov-Zhabotinskii reaction is discussed in some detail as the most extensively studied system, and the behaviour of important gas phase reactions is presented.
A Utoca T Al Ytic Reactions In Plug-Flow And Diffusion Reactors
Authors: Gray Peter , Scott Stephen K 
Published: November 2023

Abstract
Well-stirred systems are particularly convenient for the theoretician but are often less easy to realize in practice. Indeed, spatial inhomogeneities, with consequent molecular diffusion or thermal conduction processes, arise in many important situations--as varied as a single biological cell and a haystack. In the next three chapters we turn to unstirred systems, again seeking to determine ‘bifurcation’ phenomena driven by non-linear kinetics.
Complex Oscillations And Chemical Chaos
Authors: Gray Peter , Scott Stephen K 
Published: November 2023

Abstract
We have concentrated on two-variable examples hitherto because so many of the key features of oscillatory behaviour can be vividly portrayed in these terms. However, real systems all have more numerous chemical constituents and may give more complex responses than those illustrated previously. The inclusion of a third variable or varying one of the parameters of the system in time takes us to new complexities, and these are now examined. After a careful study the reader should be able to:
Dynamic Processes Studied by Two-Dimensional Exchange Spectroscopy
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander 
Published: November 2023

Abstract
The investigation of dynamic processes such as chemical exchange, cross-relaxation, nuclear Overhauser effects, spin diffusion, and cross-polarization by 2D spectroscopy has a number of advantages over the ID techniques discussed in § 4.6.1.4, particularly when the system comprises an extended network of exchange processes that occur simultaneously. The 2D methods are most useful for studying slow dynamic processes with rates that are too low to affect the lineshapes. Two-dimensional exchange spectroscopy is therefore particularly well suited for studies of cross-relaxation (transient Overhauser effects) and of spin diffusion in solids. In applications to chemical exchange, the information content of 2D exchange spectra is greatest if the temperature is chosen such that the exchange rate is fast compared to longitudinal relaxation and slow compared to the spectral parameters affected by the exchange.
Expressions for Effective Cross Sections
Authors: Mccourt Frederick R W , Beenakker Jan J M , Kohler Walter E , Kuscer Ivan 
Published: November 2023

Abstract
We have used the concept of effective cross sections extensively in previous chapters to analyze field-free transport properties (Ch. 6), field-effects on transport properties (Chs. 7, 8), optical phenomena (Ch. 9), and relaxation phenomena (Chs. 10, 11). Ultimately, we wish to be able to utilize effective cross section data in order to obtain detailed descriptions of intermolecular interactions for various molecules. In order to do this efficiently, it is important to know which effective cross sections provide independent pieces of information related to the interaction potential, and which ones, because they can be obtained as linear combinations of other effective cross sections, are useful principally as checks on the accuracy and consistency of the others.
The Near-Hydrodynamic Regime
Authors: Mccourt Frederick R W , Beenakker Jan J M , Kohler Walter E , Kuscer Ivan 
Published: November 2023

Abstract
In previous chapters where we were concerned with the hydrodynamic regime, theory was sufficiently developed and complete that discussion of the experimental results was straightforward. For the near hydrodynamic regime, however, where boundary layers and Burnett effects both play a role, the situation is quite different. For this reason, it is important to establish the experimental facts so far as possible independently of specific theoretical approaches. Indeed, the value of various phenomenological theories can only be established by looking at their success or failure with respect to all available reliable experimental data.
Tables of Transport Coefficients and Effective Cross Sections
Authors: Mccourt Frederick R W , Beenakker Jan J M , Kohler Walter E , Kuscer Ivan 
Published: November 2023

Abstract
We have seen in Chs. 2, 5-7, 10, 11 that the various transport and relaxation phenomena can be expressed in terms of effective cross sections. These effective cross sections contain all the relevant information related to the intermolecular interaction. It is therefore often convenient to give values of relevant cross sections extracted from experimental measurements together with, or even instead of, the transport coefficients or the relaxation parameters themselves.
Generalities On 2D Spectroscopy. J Spectroscopy
Authors: Goldman Maurice 
Published: November 2023

Abstract
This is the first of three chapters devoted to the description of 2D spectroscopy and related methods. These methods have produced a qualitative change in NMR spectroscopy, both in liquids and in solids, through the numerous and versatile ways they provide for tackling spin systems and extracting information on their nuclear magnetic properties, and from there on the structural, conformational and dynamic properties of the molecules to which the nuclear spins belong. In particular in liquids, it is only with these methods that NMR spectroscopy can be extended to the detailed study of the large molecules of biological systems, which has turned NMR into a fundamental tool in the fields of biochemistry and molecular biology.
α-Substitution using chiral enolates
Authors: Procter Garry 
Published: November 2023

Abstract
Substitution at the a position of chiral enolates is a large and important area of asymmetric synthesis, which has been thoroughly reviewed. This chapter is concerned mainly with the alkylation of enolates which are chiral by virtue of being attached to a chiral auxiliary (see Chapter 2) or an equivalent. Nevertheless the general principles involved can be extended to the reactions of other enolates as the concepts which are used to account for the stereoselectivity of alkylation of such enolates can be applied to the reactions of other enolates.
CRYSTALS - a programmable program
Authors: Watkin D J 
Published: November 2023

Abstract
A program is only useful if people use it, and people do not like using new or difficult programs. My greatest pleasure when starting to use a PC clone was discovering a VAX EDT emulator for it. This resistance to change and complexity is common, and presents the programmer with a difficult challenge. There are various partial solutions to the problem. One is to leave the user with few options, in the belief that the efficacy of the program is unlikely to be increased by giving the user control over the intimate workings of the program. This policy works well when the domain of operation of the program is small, and has been exhaustively researched. Modern direct-methods programs are crystallographic examples from this class, where the run-time intervention required by the user is now reduced to almost nothing. Programs like this are good candidates for background computation.
Elimination and addition-elimination reactions
Authors: Westwell Andrew D , Williams Jonathan M J 
Published: November 2023

Abstract
When two groups are lost from adjacent atoms to form an alkene the process is known as (3-elimination. This type of reaction can be readily divided into two major categories, depending on the species eliminated. Thus, alkenes may be formed by the elimination of H-X (type 1) or X-X (type 2) as shown in Scheme 5.1. Type 1 and type 2 reactions will be treated separately, and a final section will be concerned with the synthesis of alkenes via addition of enolates to carbonyl compounds followed by dehydration.