bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent advances in the PROTEIN program system for the X-ray structure analysis of biological macromolecules
Authors: Steigemann W 
Published: November 2023

Abstract
The PROTEIN program package has been designed as a compact system for the X-ray structure analysis of proteins. With the objective in mind of providing user-friendliness in terms of functionality, generality, common file structure, and format free command input within a unified program package, the program system has become wide spread within the crystallographic community over its 15 years of existence (some 150 installations worldwide). After a few years of minor improvements a major step in the development has been taken within the last year. Version 3 of the package has been launched with an enhanced file structure (provision for standard deviations of observations, several phase sets, anisotropic scaling, etc.) and with a functional extension by incorporating and improving previously separate supplementary programs. In particular, these comprise phase combination by use of Hendrickson-Lattman coefficients, statistics on the quality of phase information or their combination, a very general structure factor setup program (for any kind of map), data screening of outliers of derivative data on the basis of comparison with native data, direct support of PROTEIN like map files from the real space search routines, etc.
Improved productivity through crystallographic packages
Authors: Frenz B 
Published: November 2023

Abstract
Any crystallographic software system must contain the essentials: data reduction, structure solution, structure refinement, derived results. However, because of the variance in crystals, chemical composition, molecular weight, and space group, a complete system must include a plethora of optional functions that extend beyond the basics, in a sense, the more functions the better because one never knows what crystallographic problems will appear on the horizon. Table I gives a checklist of functions that would be useful in a complete system. To my knowledge no single package contains all the items listed, however the Personal SDP includes 92% of them.
Computational protein sequence analysis as an aid in solving protein structure
Authors: Sibbald P R 
Published: November 2023

Abstract
The analysis of protein sequences can assist in solving protein structures. Here an overview of various tools and methods is given and their uses and limitations are discussed. This paper is written for experimentalists who want to solve protein structures and are interested in analysing protein sequences to assist in the task. Practical aspects of the problem are emphasized, concentrating on existing databases and useful methods rather than on algorithms or theoretical considerations. The following questions are addressed:
Chemistry in relation to toxicity and to risks of exposure to organotin compounds
Authors: Aldridge W N 
Published: November 2023

Abstract
Toxicity is a multi-faceted property; between exposure of the organism and the expression of toxicity, as signs or symptoms of poisoning, are many stages which have different mechanisms and different doseresponse and structure-activity relationships. Central to an understanding of toxicity is the initiating reaction(s) of the toxic chemical with important macromolecules (targets) which causes changes in the controlling systems within the affected cell. Toxicity is therefore a chemical problem in biology.
Ionophoretic activity and biological effects of triorganotin compounds
Authors: Selwyn M J 
Published: November 2023

Abstract
The toxicity of triorganotin compounds is considered in relation to their hydrophobicity, inhibition of oxidative phosphorylation by blocking H --conduction through the F component of the mitochondrial ATPase, inhibition of other enzymes, and catalysis of C1- /OH- exchange across membranes.
High quality silicon nitride powder derived from Malaysian rice husks
Authors: Rahman Ismail Abdul , Riley Frank L 
Published: November 2023

Abstract
a-Silicon nitride powder has been prepared by nitriding pyrolysed rice husks incorporated with 4 per cent pre-formed silicon nitride at a temperature of about 1450°C and under a 95 per cent N/5 per cent H atmosphere. The silicon nitride powder is obtained in the form of equiaxed, sub-micrometer, and uniformly distributed particles. A material evaluation based on its powder characteristics, hot-pressing behaviour, and other properties shows that this silicon nitride is of a good quality compared to that of the best currently available commercial powders. Thus, rice husks are a good, cheap, and readily available raw material for the production of high quality silicon nitride.
A silicon semiconductor strain device for acoustic power measurement
Authors: Singh V R , Prasad Awadhesh 
Published: November 2023

Abstract
The effect of ultrasonic stress on the chemical properties of a silicon strain device has been studied. Possible chemical mechanisms which account for crystallographic orientation and resistivity are discussed in some detail. The sensitivity of the silicon strain gauge to ultrasonic stress shows a linear dependence. Radiation pressures from ultrasonic therapy sources have been measured with the silicon strain gauge transducer based on the calibration of the electrical output of the device against the acoustic power outputs of standard ultrasonic sources. An ultrasonic power meter has thus been developed for potential commercial use.
Studies on the yields of silylation reactions of mineral silicates
Authors: Khan M Mazhar Bashar , Ali Saqib , Zia Irshad A , Iqbal M 
Published: November 2023

Abstract
The trimethylsilylation reaction is of interest from the viewpoint of structural determination of silicates, and certain mineral silicates undergo this reaction in the presence of a mixture of concentrated hydrochloric acid, isopropanol, and hexamethyldisiloxane. , Cations present in the mineral are initially leached out by hydrochloric acid and the resulting silanol (Si-OH) groups then reacted with silylating reagent (trimethylsilyl chloride) to give trimethylsilylated silicates. ·6 The purpose of the present study was to explore the effect of different metal ions on the silylation of mineral silicates, and to optimize the reaction conditions for high-yield preparations of macromolecules for possible use as industrial chemicals.
Copolymerization of dimethyldivinylsilane
Authors: Oku Jun-ichi , Hasegawa Takashi , Takaki Mikio 
Published: November 2023

Abstract
The anionic polymerization of monovinylsilanes was first reported in 1963, and a brief report on the polymerization of dimethyldivinylsilane (DMDVS) which appeared in 1969 described a soluble polymer which was obtained with n-butyllithium as initiator (molar ratio monomer:initiator = 9:1). However, no detailed analyses of the polymer were carried out by the authors.
Synthesis of coenzyme On and quinonoid antibiotics by using allyltrialkyltins: control of regio- and stereochemistry in fluxional pentadienyltins and their application to chiral anthracyclinone synthesis
Authors: Maruyama Kazuhiro , Naruta Yoshinori , Nishigaichi, Yutaka , Tachikawa Noboru 
Published: November 2023

Abstract
Pentadienyl anions, unsymmetrically substituted at the 2-position, were trapped using Me SiCI and Me SnCI to give the corresponding pentadienylmetals which show marked differences in their regioselectivity. The tin electrophile gave (Z)-2-substituted isomers in high selectivity up to 96 per cent regardless of the nature of the substituents. On the other hand, the silicon electrophile gave (Z)-4-substituted products with moderate to high selectivity. The difference is explicable in terms of the preferential 1,5-Me Sn sigmatropic shift in the pentadienyltin systems towards the thermodynamically more stable s-trans isomers.
Synthesis and X-ray structural characterization of novel doubly asymmetric 8-dimethylaminonaphthyl(― )-menthylorganotin compounds
Authors: Schumann Herbert , Wassermann, Birgit Corinna , Pickardt Joachim 
Published: November 2023

Abstract
Menthylmethyltin dibromide (1) reacts with 8-dimethylaminonaphthyllithium etherate to give the doubly asymmetric 8-dimethylaminonaphthyl-(― )-menthylmethyltin bromide (2), in which a chiral carbon atom of an optically active ligand is bound to a chiral tin centre. The molecular structure of 2 shows a diastereomerically pure compound with an absolute configuration of Rsn at the pentacoordinated tin atom.
Crystal structure of tri-n-butyltin(IV) N-methyl-N-phenyldithiocarbamylacetate, (n-C4H9)3SnOC(O)CH2SC(S)N(CH3) (C6Hs)
Authors: Weng Ng Seik , Wei Chen , Das V G Kumar , Keong, Yap Chee , Butcher Ray J 
Published: November 2023

Abstract
Triorganotin carboxylate esters display several structural variations: triphenyltin thiophene-2-carboxylate is a monomeric molecule, triphenyltin pyridine- 3-carboxylate a flat, pyridyl-bridged polymer and triphenyltin 8-quinolyloxyacetate a water-coordinated, hydrogen-bonded helical chain; the carboxyl oxygen is not involved in either intra- or intermolecular coordination to tin in the three compounds. On the other hand, triphenyltin chloroacetate and triphenyltin 3-benzoylpropionate are carboxylate-bridged, a feature common to triorganotin esters whose carboxylate group is an acetate derivative. In continuation of our studies on triorganotin carboxylates, we report the crystal structure of tri-n-butyltin N-methyl-N-phenyldithiocarbamylacetate.
Multiple-Quantum Transitions
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander 
Published: November 2023

Abstract
In the past, multiple-quantum transitions have often been neglected in favour of the more easily accessible single-quantum transitions. Many traditional texts on the practical aspects of magnetic resonance hardly mention the existence of the numerous stepbrothers of the one-quantum transitions. Although it is possible to observe multiple-quantum transitions by conventional slow-passage techniques, it is a thorny path and few spectroscopists have ventured to animate the sleeping beauty. Some of the brave scientists were Yatsiv (5.1) and Freeman, Anderson, and Reilly (5.2).
Epitome Of Quantum Mechanics
Authors: Goldman Maurice 
Published: November 2023

Abstract
As stated in the preface, it is only through the use of quantum mechanics that one can get a real understanding of the working of the sophisticated methods that turned high-resolution NMR into a fundamental and powerful tool for the investigation of molecules, especially in the liquid state. However useful, the classical and naive quantum descriptions given in Chapter 1 suffice only for interpreting the simplest version of NMR spectroscopy, namely the resonance spectra obtained either by the CW method or by the Fourier transform of the FID following a single r.f. pulse. As regards methods such as 2D spectroscopy, these descriptions are fundamentally inadequate and provide at best a qualitative and more-or-less intuitive feeling of what happens, very often with serious conceptual difficulties.
Quantum Statistical Mechanics
Authors: Goldman Maurice 
Published: November 2023

Abstract
NMR is not performed on a single or a small number of spins, but on a very large number, comparable with the Avogadro number. Even when one is interested in a molecular species with relatively few spins, the sample contains a large number of molecules of that species, all of which are observed simultaneously. What one observes in practice is the average response of the molecules, which is determined by an average over the states of each individual molecule. A common feature of all studies of condensed matter is that in the presence of many identical objects it is impossible to know exactly the state of the whole system, but that this relative ignorance is immaterial in so far as the properties of the system are not very sensitive to its exact state. The approach adapted to macroscopic systems is a statistical one, the correctness and fruitfulness of which is witnessed by the unfailing success of statistical mechanics. When dealing with quantum objects, the statistical approach must be adapted to their quantum character.
Fundamentals Of Relaxation Theory
Authors: Goldman Maurice 
Published: November 2023

Abstract
Relaxation is the name given to the phenomenon of evolution towards statistical equilibrium of macroscopic systems. The case in which we are interested is that when the whole system consists of two weakly coupled parts: the spin system consisting of all degrees of freedom dependent on the spin operators of the nuclei, and the lattice consisting of all other degrees of freedom of the liquid sample, associated with the molecular rotations and translations. Nuclear magnetic relaxation is in that case the evolution of the spin system towards thermal equilibrium with the lattice, and is called spin-lattice relaxation. The lattice is an ‘infinite’ thermostat, in the sense that its own thermal equilibrium state is not affected by the exchange of energy with the spin system taking place during relaxation.
Macromolecular Data Processing :For Area Detectors with Program System MADNESS
Authors: Messerschmidt Albrecht 
Published: November 2023

Abstract
During the last decade electronic area detector systems have become commercially available for data collection in X-ray crystallography of macromolecules. The area detector may be a multiwire proportional counter (MWPC) as in the system developed by Hamlin, Xuong and collaborators at the University of California, San Diego, USA (Cork, Hamlin, Vernon, Xuong, and Perez-Mendez, 1985) and in the Xentronics-Nicolet-Siemens system or a television-camera as in the FAST-diffractometer from EnrafNonius, Delft. During the last few years image plate systems (e.g. EMEL/Mar Research, Hamburg or Rigaku/MSC, Tokyo, Texas) have been developed especially for crystallographic applications.
Standardization -portability of crystallographic data
Authors: McMahon Brian 
Published: November 2023

Abstract
The title of this lecture refers to portability and standardization. Portability - the ability to transfer information from one location to another - is of course a desirable facility Standardization - the establishment of agreed terms for defining specific information - is the way to achieve this. There are three types of portability we may consider, and we shall see how the various standards required to enable each type of portability can come together to provide a high-level specification for a data structure that allows a highly portable form of data transfer in our science of crystallography.
Advances in computing for macromolecular crystallography
Authors: Bourne Philip E 
Published: November 2023

Abstract
In 1990 at the XVth IUCr Congress in Bordeaux, Keith Watenpaugh gave a paper with this same title. The paper outlined how crystallographers were applying current hardware and software technology to problems of macromolecular structure determination using X-ray diffraction techniques. Many of the innovations summarized at that meeting were subsequently presented in more detail at the Bischenberg Summer School on Crystallographic Computing (Moras, Podjarny, and Thierry, 1991). In small part this paper is an update to that report, tabulating several specific software developments that have occurred in the last two years. fn large part this paper is a commentary on parallel developments in the fields of macromolecular crystallography and computer technology, and makes the case for changes in the way we practice crystallographic computing if we arc to remain a first rate example of the success in applying computer technology to a scientific discipline.
The Cambridge structural database: current directions developments and future directions
Authors: Edgington Paul R 
Published: November 2023

Abstract
The Cambridge Structural Database (CSD) contains bibliographic, 2D chemical and 3D structural results for organocarbon compounds studied by X-ray or neutron diffraction. The Cambridge Crystallographic Data Centre (CCDC) which maintains the database was established in 1965. The CCDC is not only responsible for the maintenance of the database but also produces and distributes the software to enable the searching and analysis of the stored information. The complete package, database plus software, is referred to as the CSD system.
The application of the structure correlation method for studying reaction mechanism and transition state geometry
Authors: Kaftory Menahem 
Published: November 2023

Abstract
Roald Hoffinann’s famous quotation “There is no more basic enterprise in chemistry than the determination of the geometrical structure of a molecule. Such a determination, when it is well done, ends all speculation as to the structure and provides us with the starting point for the understanding of every physical, chemical and biological property of the molecule.…” provides us with a challenge. All the information about the molecular structure, whether it was obtained by theoretical calculations or by experimental methods, is available for us to try and deduce the relation between structure and physical, chemical or biological properties. The main problem is how to analyze the results and what kind of correlations exist between the available data and the relevant property. The understanding of a chemical reaction cannot be complete without knowing the structural variation of the reactants participating in the process. Molecules that are involved in a reaction have shape; they are not just a bunch of electron densities, and not a collection of representative numbers.
Structure–activity relationships of benzisoselanazoles
Authors: Piątek M , Oleksyn B J , Śliwinśki J 
Published: November 2023

Abstract
Selenium is an essential component of several biologically important macromolecules. Within the last few years it has been shown that selenium exerts protective and/or curative action against certain human diseases and maintains the integrity of immune reactions. Some of the organoselenium compounds synthesized recently, such as 2-phenyl-2H-benzisoselenazole-l,2 one-3, named Ebselen, were reported to possess remarkable biological activity. Selenium -oriented research has confirmed that many benzisoselenazoles exhibit anti -inflammatory, anti -cancer and immunostimulating activity. Ebselen displays protective action against inflammation and rheumatoid arthritis and has, therefore, been actively investigated and tested as a potential drug for clinical use.
Structure and stereochemistry of some ribofuranosyl nucleosides and related imidazole compounds
Authors: Briant C E , Jones D W , Shaw J D 
Published: November 2023

Abstract
Among the many nucleoside and nucleotide crystal structures that have been reported, rather few involve the five-membered imidazole ring (which has similarities with the five-membered ring in the common purines adenine, guanosine and inosine). Some of the 2,3-O-isopropylidene Nglycosylimidazole nucleosides synthesized by Professor G. Shaw and colleagues (Cusack et al., 1973; Mackenzie et al., 1976) are related to active intermediates in the de novo biosynthesis of nucleotides and to biologically active naturally occurring nucleosides, generally as β anomer.
Polymorphism of 6-methyluracil
Authors: Gladkikh 0. P , Masunov A E , Leonidov N B , Belsky V K 
Published: November 2023

Abstract
Most well-known synthetic biologically active and medical preparations are produced as powders, i.e. in the solio state. However, when such substances crystallize, several polymorphic modifications with different physical-chemical and physiological properties may form CMcCrone, 1963; Bernstein, 1989). Frequently polymorphism causes the variable bioactivity of different samples of one chemical compound.
The balance between order and disorder
Authors: Williams R J P , Da Silva J J R Frausto 
Published: November 2023

Abstract
In Chapter 1 we took as a historical starting point for the discussion of all observations concerning the material objects we sense around us the four ‘elements’ of certain Greek philosophers and scientists such as Aristotle (Fig. l. 1). We also noted the relationship to similar thinking in Chinese philosophy (Fig. 1.5). We have shown so far that, according to today’s views, three of the classical ‘elements’-air, water and earth-are more or less directly related to the physical states of materials (gases, liquids and solids). Moreover, as examined in Chapter 2, materials themselves of every kind are now known to be made from the fixed number of chemical elements of the periodic table (Fig. 1. 7). These elements came together in ordered, often shaped constructs to make molecular gases and condensed systems, and thence all chemical material things on Earth (and elsewhere), due to what we call ‘forces’, which can still be said to be related to the Greek idea of underlying ‘form’. The main forces of concern are those that we have labelled gravitational and electromagnetic (see Chapter 1). The fourth Greek ‘element’-fire (or heat and light)-can transform solids to liquids to gases; the Greeks connected it also to underlying ‘form’ and therefore made it similar in kind to the other three ‘elements’.
Spectroscopy, chirality, and oriented systems
Authors: Rodger Alison , Norden Bengt 
Published: November 2023

Abstract
Many of the questions we ask about chemical and biological systems relate to what shapes molecules have and how they interact with each other. New or modified methods are constantly being developed to address these questions, either in response to new problems or as the result of technical advances. The aim of this book is to show how circular dichroism (CD) and linear dichroism (LD) spectroscopies can be used to provide information about molecular structure and about interactions between molecules.
Total Synthesis of Cryptophycin C
Authors: Barrow R A , Hemscheidt T , Liang J , Paik S , Moore R E , Tius, M A 
Published: November 2023

Abstract
Discussion Points DMF Suggest a synthesis for compound 1. Explain the regioselectivity in the epoxide opening of step c. A considerable amount of compound 15 was formed when step e was carried out in the absence of 2,2-dimethoxypropane. Give mechanisms for steps h and u. Further Reading For studies on the regioselectivity in epoxide opening, see: M. Chini, P. Crotti, L.A. Flippin, C. Gardelli, E. Giovani, F. Macchia, M. Pineschi, J. Org. Chem.,1993, 58,1221; M. Chini, P. Crotti, C. Gardelli and F. Macchia, Tetrahedron,1994, 50,1261. For a review on ring-closure methods in the synthesis of natural products, see: Q. C. Meng and M. Hesse, Top. Curr. Chem.,1992, 161,107. For a modification of the allyl group removal procedure, see: A. Merzouk and F. Guibe, Tetrahedron Lett., 1992,33, 477.