bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Li Synthesis of (–)-Fusarisetin A
Authors: Taber Douglass F. 
Published: November 2020

Fusarisetin A 3 is an intriguing inhibitor of cell migration and invasion that is not itself cytotoxic. Ang Li of the Shanghai Institute of Organic Chemistry developed (J. Am. Chem. Soc. 2012, 134, 920) a total synthesis of (–)-fusarisetin A, demonstrating that the natural material had the absolute configuration opposite to that originally assigned. A key step in the synthesis was the highly diastereoselective cyclization of 1 to 2. The absolute configuration of 1 and so of synthetic 3 was derived from commercial citronellol, which is prepared on an industrial scale by asymmetric synthesis. To this end, the reagents 6 and 8 were required. The β-ketothio ester 6 was prepared from the Meldrum’s acid 4 and the phosphonate 8 was derived from methyl sorbate 7. The acetal of citronellal 9 was ozonized with reductive work-up to give the alcohol 10. Protection followed by hydrolysis gave the aldehyde 11, which was condensed with 8 to give the triene 12. Deprotection followed by oxidation delivered an aldehyde, which was condensed with 6 to give the Diels-Alder precursor 1. With BF3 • OEt2 catalysis, the Diels-Alder cycloaddition proceeded under mild conditions, –40oC for 40 min, leading to 2 as a single diastereomer. Comparable intramolecular Diels-Alder cyclizations with single carbonyl activation gave mixtures of diastereomers. The alcohol 13 was prepared by transesterification of 2 with trifluoroethanol. Activation with MsCl led directly to the kinetic O-alkylation product 14. Following the precedent of Trost (J. Am. Chem. Soc. 1980, 102, 2840), exposure to a Pd catalyst smoothly converted 14 into 15 as the desired diastereomer. Condensation of the ester 15 with the amine 16 gave the diene 17. Selective oxidation of the monosubstituted alkene under Wacker conditions gave the ketone, which was reduced selectively by the Luche protocol to the alcohol 18. Exposure of 18 to NaOCH3 initiated Dieckmann cyclization, leading to (–)-fusarisetin A 3.
Generative Sets and Creative Systems
Authors: Smullyan Raymond M 
Published: November 2020

Abstract
we now have the background to study the beautiful subject of creative and productive sets inaugurated by Emil Post [1944]. This plays a key rôle in the metamathematical study of incompleteness and undecidability. §1. Productive and Creative Sets. To say that a set A is not r.e. is equivalent to saying that for any r.e. subset ωi of A, there is a number in A not in ωi . A is called productive if there is a recursive function f(x)—called a productive function for A—such that for any number i, if ωi Í A, then f(i) Î A - ωi . [Informally, this means that it is not only true that no r.e. subset of A is A, but given any such r.e. subset, we can effectively find a number which is in A but not in the subset.] A set A is called creative (after Post) if it is r.e., and its complement is productive. Let us note that a productive function for the complement of a set A is a recursive function f(x) such that for any number i such that ωi is disjoint from A, the number f(i) lies outside both ωi and A. A system S is called productive if the set P of Gödel numbers of the provable formulas of S is a productive set; S is called creative if the set P is creative. As we will see, the complete theory N is not only not axiomatizable but is productive, and the system P.A. is not only undecidable but creative. Post’s Sets C and K. A simple example of a creative set is Post’s set C —the set of all numbers x such that x Î ωx. Thus for any number i, i Î C ↔ i Î ωi. If ωi is disjoint from C, then i is outside both ωi and C and, therefore, the identity function I(x) is a productive function for C͂. Therefore, C͂ is productive, and since C is obviously r.e., C is creative.
Rheology and Processing of Polymeric Materials: Volume 1: Polymer Rheology
Authors: Han Chang Dae 
Published: November 2020

Abstract
Volume 1 presents first fundamental principles of the rheology of polymeric fluid including kinematics and stresses of a deformable body, the continuum theory for the viscoelasticity of flexible homogeneous polymeric liquids, the molecular theory for the viscoelasticity of flexible homogeneous polymeric liquids, and the experimental methods for the measurement of the rheological properties of poylmeric liquids. The materials presented are intended to set a stage for the subsequent chapters by introducing the basic concepts and principles of rheology, from both phenomenological and molecular perspectives, ofstructurally simple flexible and homogeneous polymeric liquids. Next, this volume presents the rheological behavior of structurally complex polymeric materials including miscible polymer blends, block copolymers, liquid-crystalline polymers, thermoplastic polyurethanes, immiscible polymer blends, perticulare-filled polymers, organoclay nanocomposites, molten polymers with dissolved gas, and thermosts.
Relationships Between Polymer Rheology and Polymer Processing
Authors: Han Chang Dae 
Published: November 2020

Abstract
Polymer products have long been used for a variety of applications in our daily lives, as well as for some more exotic applications, such as biomedical devices, superhigh- speed airplanes, and outer-space vehicles. Other applications are too numerous to mention them all here. There are many steps involved in the production of polymer products, from the synthesis of raw materials to the manufacturing of the finished products. Of the many steps involved, the fabrication (processing) step plays a pivotal role in determining the quality of the final products. Successful processing of polymeric materials requires a good understanding of their rheological behavior (Han 1976, 1981). Thus, intimate relationships exist between polymer rheology and polymer processing. In this chapter we describe briefly some of these close relationships between polymer rheology and polymer processing. Rheology is the science that deals with the deformation and flow of matter. Hence, polymer rheology is the science that deals with the deformation and flow of polymeric materials. Since there are a variety of polymeric materials, we can classify polymer rheology further into different categories, depending upon the nature of the polymeric materials; for instance, (1) the rheology of homogeneous polymers, (2) the rheology of miscible polymer blends, (3) the rheology of immiscible polymer blends, (4) the rheology of particulate-filled polymers, (5) the rheology of fiberglass-reinforced polymers, (6) the rheology of organoclay nanocomposites, (7) the rheology of polymeric foams, (8) the rheology of thermosets, (9) the rheology of block copolymers, and (10) the rheology of liquid-crystalline polymers. Each of these polymeric materials exhibits its own unique rheological characteristics. Thus, different theories are needed to interpret the experimental results of the rheological behavior of different polymeric materials. However, at present we do not have a comprehensive theory that can describe the rheological behavior of some polymeric materials and thus we must resort to empirical correlations to interpret the experimentally observed rheological behavior of those materials. It is then fair to state that a complete understanding of the rheological behavior of all polymeric materials remains quite a challenge indeed.
Continuum Theories for the Viscoelasticity of Flexible Homogeneous Polymeric Liquids
Authors: Han Chang Dae 
Published: November 2020

Abstract
There are two primary reasons for seeking a precise mathematical description of the constitutive equations for viscoelastic fluids, which relate the state of stress to the state of deformation or deformation history. The first reason is that the constitutive equations are needed to predict the rheological behavior of viscoelastic fluids for a given flow field. The second reason is that constitutive equations are needed to solve the equations of motion (momentum balance equations), energy balance equations, and/or mass balance equations in order to describe the velocity, stress, temperature, and/or concentration profiles in a given flow field that is often encountered in polymer processing operations. There are two approaches to developing constitutive equations for viscoelastic fluids: one is a continuum (phenomenological) approach and the other is a molecular approach. Depending upon the chemical structure of a polymer (e.g., flexible homopolymer, rigid rodlike polymer, microphase-separated block copolymer, segmented multicomponent polymers, highly filled polymer, miscible polymer blend, immiscible polymer blend), one may take a different approach to the formulation of the constitutive equation. In this chapter we present some representative constitutive equations for flexible, homogeneous viscoelastic liquids that have been formulated on the basis of the phenomenological approach. In the next chapter we present the molecular approach to the formulation of constitutive equations for flexible, homogeneous viscoelastic fluids. In the formulation of the constitutive equations using a phenomenological approach, emphasis is placed on the relationship between the components of stress and the components of the rate of deformation (or strain) or deformation (or strain) history, such that the responses of a fluid to a specified flow field or stress can adequately be described. The parameters appearing in a constitutive equation are supposed to represent the characteristics of the fluid under consideration. More often than not, the parameters appearing in a phenomenological constitutive equation are determined by curve fitting to experimental results. Thus phenomenological constitutive equations shed little light on the effect of the molecular parameters of the fluid under investigation to the rheological responses of the fluid.
Rheology of Flexible Homopolymers
Authors: Han Chang Dae 
Published: November 2020

Abstract
Numerous flexible homopolymers and flexible random copolymers are commercially available. Thus, understandably, a number of research groups have reported on the rheological behavior of flexible homopolymers and flexible random copolymers in the bulk and solution states. There are too many studies to cite them all here. In Chapters 3 to 5 we presented the rheological behavior, in general terms, of linear flexible homopolymers in steady-state shear flow, elongational flow, and/or oscillatory shear flow. In this chapter, we present the effects of temperature, molecular weight (although in Chapter 4 we presented theoretical predictions of the effect of molecular weight), and molecular weight distribution on the rheological behavior of linear flexible homopolymers, and also flexible homopolymers with long-chain branching. The rheological behavior of much more complex polymer systems is presented in other chapters of this volume. From the point of view of polymer processing, temperature is one of the most important variables that greatly affect the rheological behavior of polymeric liquids. Therefore, it is very important to present the effect of temperature on rheological behavior, placing emphasis on the methods that enable one to obtain temperature-independent correlations for rheological properties. Such correlations, when available, will help one to estimate the rheological properties of the same polymer without conducting additional experiments. With respect to polymer synthesis and polymer processing, a better understanding of the effects of molecular weight and molecular weight distribution on the rheological behavior of a polymer is of fundamental importance. In Chapter 4 we have presented molecular theory, demonstrating that the molecular weight of a linear flexible homopolymer has a profound influence on its rheological properties. Thus, information on the relationships between molecular weight and rheology, when available, will help one to choose, with little waste of time and effort, optimum processing conditions. One of the common features of all commercial homopolymers is that they are polydisperse and, therefore, it is not difficult to surmise that the molecular weight distribution of a polymer also has a profound influence on its rheological properties.
Rheology of Molten Polymers with Solubilized Gaseous Component
Authors: Han Chang Dae 
Published: November 2020

Abstract
Polymer melts (or polymer solutions) with a solubilized gaseous component (which occur under sufficiently high pressures, thus forming homogeneous mixtures), and polymer melts (or polymer solutions) with dispersed gas bubbles (thus forming heterogeneous mixtures of polymeric fluid and gas bubbles) are encountered in thermoplastic foam processing and polymer devolatilization. Thus, a good understanding of the rheological behavior of such mixtures is very important to the design of processing equipment and successful optimization of such polymer processing operations. From the 1950s through the 1970s, the dynamics of a single, spherical gas bubble dispersed in a stationary Newtonian or viscoelastic medium was extensively reported in the literature (Barlow and Langlois 1962; Duda and Vrentas 1969; Epstein and Plesset 1950; Folger and Goddard 1970; Marique and Houghton 1962; Plessst and Zwick 1952; Rosner and Epstein 1972; Ruckenstein and Davis 1970; Scriven 1959; Street 1968; Street et al. 1971; Tanasawa and Yang 1970; Ting 1975; Yang and Yeh 1966; Yoo and Han 1982; Zana and Leal 1975). While such investigations are of fundamental importance in their own right, they are not much help to describe bubble dynamics in thermoplastic foam extrusion or structural foam injection molding, for instance. There is no question that an investigation of bubble dynamics in a flowing molten polymer with dispersed gas bubbles is a very difficult subject by any measure. Thus, understandably, a relatively small number of research publications on bubble dynamics in a flowing molten polymer have been reported (Han and Villamizar 1978; Han et al. 1976; Yoo and Han 1981). The complexity of the problem arises from other related issues, such as the solubility and diffusivity of gaseous component(s) in a flowing molten polymer, which in turn depend on temperature and pressure of the system. Further, a gaseous component solubilized in molten polymer in the upstream side of a die, for instance, may nucleate as the pressure of the fluid stream decreases along the die axis, after which they could grow continuously as the molten polymer with dispersed gas bubbles flows through the rest of the die.
On Computable Numbers: Corrections and Critiques
Authors: Turing Alan , Post Emil 
Published: November 2020

Abstract
As is not uncommon in work of such complexity, there are a number of mistakes in ‘On Computable Numbers’. Turing corrected some of these in his short note 2.1, published in the Proceedings of the London Mathematical Society a few months after the original paper had appeared. The mathematician Emil L. Post’s critique of ‘On Computable Numbers’ was published in 1947 and formed part of Post’s paper ‘Recursive Unsolvability of a Problem of Thue’. Post is one of the major figures in the development of mathematical logic in the twentieth century, although his work did not gainwide recognition until after his death. (Born in 1897, Post died in the same year as Turing.) By 1936 Post had arrived independently at an analysis of computability substantially similar to Turing’s. Post’s ‘problem solver’ operated in a ‘symbol space’ consisting of ‘a two way infinite sequence of spaces or boxes’. A box admitted ‘of but two possible conditions, i.e., being empty or unmarked, and having a single mark in it, say a vertical stroke’. The problem solver worked in accordance with ‘a fixed unalterable set of directions’ and could perform the following ‘primitive acts’: determine whether the box at present occupied is marked or not; erase any mark in the box that is at present occupied; mark the box that is at present occupied if it is unmarked; move to the box to the right of the present position; move to the box to the left of the present position. Later, Post considerably extended certain of the ideas in Turing’s ‘Systems of Logic Based on Ordinals’, developing the important field now called degree theory. In his draft letter to Church, Turing responded to Post’s remarks concerning ‘Turing convention-machines’. It is doubtful whether Turing ever sent the letter. The approximate time of writing can be inferred from Turing’s opening remarks: Kleene’s review appeared in the issue of the Journal of Symbolic Logic dated September 1947 (12: 90–1) and Turing’s ‘Practical Forms of Type Theory’ appeared in the same journal in June 1948.
History of Hut 8 to December 1941 (1945)
Authors: Mahon Patrick 
Published: November 2020

Abstract
Patrick Mahon (A. P. Mahon) was born on 18 April 1921, the son of C. P. Mahon, Chief Cashier of the Bank of England from 1925 to 1930 and Comptroller from 1929 to 1932. From 1934 to 1939 he attended Marlborough College before going up to Clare College, Cambridge, in October 1939 to read Modern Languages. In July 1941, having achieved a First in both German and French in the Modern Languages Part II, he joined the Army, serving as a private (acting lancecorporal) in the Essex Regiment for several months before being sent to Bletchley. He joined Hut 8 in October 1941, and was its head from the autumn of 1944 until the end of the war. On his release from Bletchley in early 1946 he decided not to return to Cambridge to obtain his degree but instead joined the John Lewis Partnership group of department stores. John Spedan Lewis, founder of the company, was a friend of Hut 8 veteran Hugh Alexander, who effected the introduction. At John Lewis, where he spent his entire subsequent career, Mahon rapidly achieved promotion to director level, but his health deteriorated over a long period. He died on 13 April 1972. This chapter consists of approximately the first half of Mahon’s ‘The History of Hut Eight, 1939–1945’. Mahon’s typescript is dated June 1945 and was written at Hut 8. It remained secret until 1996, when a copy was released by the US government into the National Archives and Records Administration (NARA) in Washington, DC. Subsequently another copy was released by the British government into the Public Record Office at Kew. Mahon’s ‘History’ is published here for the first time. Mahon’s account is first-hand from October 1941. Mahon says, ‘for the early history I am indebted primarily to Turing, the first Head of Hut 8, and most of the early information is based on conversations I have had with him’.
Letter to Winston Churchill (1941)
Authors: Turing Alan , Welchman Gordon 
Published: November 2020

Abstract
During 1941, codebreaking at Bletchley Park was hindered by shortages of typists and unskilled staff. These shortages could have been easily rectified, but the codebreakers’ urgent requests were ignored by offcials in Whitehall. Going over the heads of those in command at GC & CS, Turing and his co-signatories wrote directly to the Prime Minister, Winston Churchill. On receiving the letter Churchill minuted his Chief of Staff, General Ismay: ‘action this day Make sure they have all they want on extreme priority and report to me that this had been done.’ It fell to Stuart Milner-Barry of Hut 6 to deliver the letter by hand to 10 Downing Street. In 1986, Milner-Barry recalled his trip to Whitehall: Why I was deputed to carry the letter to No. 10 I do not remember—at a guess, because I was the most readily expendable from the scene of action. What I do recall is arriving at Euston Station, hailing a taxi, and with a sense of total incredulity (can this really be happening?) inviting the driver to take me to 10 Downing Street. The taxi-driver never blinked an eyelid: without comment he directed himself to Whitehall. Arrived at the entrance to Downing Street, I was again surprised at the lack of formality: there was just a wooden barrier across the road, and one uniformed policeman who waved my driver on. At the door to No. 10 I paid off the taxi, rang the bell, was courteously ushered in, explained that I had an urgent letter which I was anxious to deliver to the Prime Minister personally, and was invited to wait. Of course I did not see the Prime Minister himself; but very shortly there appeared a dapper dark-suited figure of shortish stature whom I subsequently identified as Brigadier Harvie-Watt, Mr. Churchill’s PPS from 1941 to 1945. To him I again explained my errand; and while obviously and understandably puzzled as to who I might be and what this was all about, he took me sufficiently seriously to promise that he would without fail deliver the letter to the Prime Minister and stress its urgency.
Safeguarding children
Authors: Harris J C , Welbury R 
Published: November 2020

Abstract
It is essential that everyone who provides dental care for children has an understanding of other factors that affect children’s lives. This includes non-dental aspects of their health and wider issues that affect children’s development and well-being. Child maltreatment is one such issue. Abuse and neglect are forms of maltreatment of a child. Child maltreatment involves acts of commission or omission which result in harm to a child. When health professionals work with others to take action to protect children who are suffering, or are at risk of suffering, significant harm as a result of maltreatment, this is known as ‘child protection’. Child protection sits within the context of a wider agenda to ‘safeguard’ children. Safeguarding measures are actions taken to minimize the risks of harm to children and young people. These include: • protecting children from maltreatment • preventing impairment of children’s health or development • ensuring that children are growing up in a safe and caring environment. This should enable children to have optimal life chances and to enter adulthood successfully. The foundation for the success of such work is an acceptance and understanding of children’s internationally agreed human rights. In this context the term ‘child’ includes children and young people up to the age of 18. Violence towards children has been noted between cultures and at different times within the same culture since early civilization. Infanticide has been documented in almost every culture, and ritualistic killing, maiming, and severe punishment of children in an attempt to educate them, exploit them, or rid them of evil spirits has been reported since early times. Ritualistic surgery or mutilation of children has been recorded as part of religious and ethnic traditions. In the seventeenth century values started to change and incest was seen as a crime under church law, but until the eighteenth century society viewed children as possessions of their parents who were at liberty to treat them in any way they wished. In fact, legislation to protect animals was introduced before children were afforded the same ‘privilege’.