688 research outputs found
Communicating Chemical Congregation: A Molecular AND Logic Gate with Three Chemical Inputs as a �Lab-on-a-Molecule� Prototype
No full textPT: J; CR: ABBOTT EA, 1950, FLATLAND ROMANCE MAN AMENDOLA V, 2001, ACCOUNTS CHEM RES, V34, P488 BADJIC JD, 2004, SCIENCE, V303, P1845 BAG B, 2005, CHEM COMMUN 0128, P513 BALZANI V, 2003, MOL DEVICES MACHINES BHATTACHARYA S, 2003, CHEM COMMUN, P1158 BISSELL RA, 1992, J CHEM SOC P2, P1559 CALLAN JF, 2004, CHEM COMMUN, P2048 CHANG CJ, 2004, CHEM BIOL, V11, P203 DESILVA AP, 1993, NATURE, V364, P42 DESILVA AP, 1997, CHEM REV, V97, P1515 DESILVA AP, 1997, J AM CHEM SOC, V119, P7891 DESILVA AP, 1999, J AM CHEM SOC, V121, P1393 DESILVA AP, 2001, ELECT TRANSFER CHEM, V5, P156 DESILVA AP, 2001, MOL SWITCHES, P339 DESILVA AP, 2004, CHEM-EUR J, V10, P574 DESILVA SA, 2002, CHEM COMMUN, P1360 FABBRIZZI L, 1999, ACCOUNTS CHEM RES, V32, P846 FARINAS J, 1999, J BIOL CHEM, V274, P7603 GUNNLAUGSSON T, 2003, ORG BIOMOL CHEM, V1, P3265 GUNNLAUGSSON T, 2003, ORG LETT, V5, P4065 GUNNLAUGSSON T, 2004, TETRAHEDRON, V60, P11239 GUO XF, 2004, ADV MATER, V16, P125 HE HR, 2003, ANAL CHEM, V75, P549 HE HR, 2003, J AM CHEM SOC, V125, P1468 HERNANDEZ JV, 2004, SCIENCE, V306, P1532 HIRSCH ED, 2002, NEW DICT CULTURAL LI IZATT RM, 1976, J AM CHEM SOC, V98, P7626 IZATT RM, 1985, CHEM REV, V85, P271 KOSKELA SJM, 2004, CHEM COMMUN, P945 LANKSHEAR MD, 2006, CHEM COMMUN 0214, P612 LIM NC, 2004, CHEM COMMUN 0507, P1094 MARGULIES D, 2004, J AM CHEM SOC, V126, P15400 MARGULIES D, 2005, NAT MATER, V4, P768 MILLMAN J, 1988, MICROELECTRONICS NICOLL D, 2004, DIAGNOSTIC TESTS RAYMO FM, 2002, ADV MATER, V14, P401 SAUVAGE JP, 1998, ACCOUNTS CHEM RES, V31, P611 SMITH RM, 1974, CRITICAL STABILITY C STOJANOVIC MN, 2003, NAT BIOTECHNOL, V21, P1069 TSIEN RY, 1992, AM J PHYSIOL, V263, C723 TUSA JK, 2005, J MATER CHEM, V15, P2640 UCHIYAMA S, 2004, J AM CHEM SOC, V126, P3032 UCHIYAMA S, 2005, J AM CHEM SOC, V127, P8920 WANG HM, 2004, CHEM COMMUN 0321, P670 WISKUR SL, 2001, ACCOUNTS CHEM RES, V34, P963 WOODROOFE CC, 2003, J AM CHEM SOC, V125, P11458; NR: 47; TC: 10; J9: J AM CHEM SOC; PG: 2; GA: 034GNSource type: Electronic(1
High pressure behaviour of AIP04-5 in penetrating/ non penetrating pressure medium
No full textAluminophosphate are objects of a growing research interest due to their potential technologieal and industriaI applications [e.g 1,2]. Their large channels serve as ideaI host for organie compounds and small polymers. Among those, AIP0-5 is a synthetic zeolite characterized by an open-framework of (P,AI)O4 tetrahedra. The tetrahedra are connected to form six-and twelve-membered rings, in such a way that a large channel (0~7.3À), parallel to the [001] direction, occurs. Klap et al. [3] underlines that every crystal of AIP0-5 is built up by three different microdomains, in which the positions of the framework oxygen atoms are slightly different; the main effect of the structural disorder is the very large anisotropie displacement parameters of the framework oxygens. We performed two in situ single-crystal synchrotron X-ray diffraction experiments using both penetrating (methanol:ethanol:H20 mix, m:e:w) and non-penetrating (silicon oil) pressure media [4]. The structure refinements showed that: 1) for compression in m:e:w mix, H20 molecules are absorbed at low-P regime, forming a H20-network by H-bonding interaction; 2) the elastic parameters of the super-hydrated AIP04 5 are different if compared to the one compressed in silicon oil; 3) the structural deformation mechanisms of super-hydrated and regular AIP04 -5 are different; 4) evidence of a incommensurately modulated structure occur (according to [3]), and there is an evolution of the non-Bragg reflections with pressure.
The author acknowledges the ltalian Ministry of Education, MIUR-Project: "Futuro in Ricerca 2012 -ImPACT-RBFR12CLQD".
[lJ Tang Z.K. et al. Applied Physies Letters 1998; 73, 2287-2289.
[2] Yang W.S. et al. Microporous and mesoporous materials 20i6; 219,87-92. [3J Klap G.J. et al. Mieroporous and mesoporous materials 2000; 38,403-412. [4J Gatta, G.D. Mieroporous and Mesoporous Material 2010; 128, 78-84
F.C. Hawthorne, Landmark papers : structure topology
No full textIn this second volume of the Mineralogical Society’s ‘Landmark’ series, Prof. Frank Hawthorne has selected a number of key papers, some of which are true milestones of mineralogy and crystallography, showing the acceleration of research and the increase in knowledge in the field of crystal-chemistry. The papers follow in chronological sequence, allowing the reader to see how crystallography and, particularly, mineralogy have evolved during the last 80 years. He has chosen the papers on the basis of three related aspects: (a) the nature of chemical bonds, and (b) their relation to bond topology, leading to (c) the prediction of bond topologies and their hierarchical organization. His commentaries on the selected papers provided a coherent narrative thread running through the volume. In the first chapter ‘Bond topology and Minerals’, Hawthorne reviews the long history of the mineralogy and crystallography, reporting the evolution of the knowledge and the experimental findings in the last 2,000 years. The author introduces the mathematical concept of topology and how to use this tool for the description of the structural configuration in crystals. In addition, he discusses the motivation of mineralogists for understanding and developing principles of bond topology. In chapter 2, two milestone papers by Linus Pauling (both published in 1929) on the structure of complex ionic crystals are reported and enriched with comments. Chapter 3 is devoted to a further milestone paper for mineralogy written by W.L. Bragg (1930), on the structure classification of the silicate minerals, the isomorphous replacement in silicates and on the application of the Pauling’s rules to this class of minerals. In Chapter 4, we jump to the 1970s with the paper of P.B. Moore (1970) on the stereoisomerism among octahedral and tetrahedral chains. Moore based his study not on a specific mineral structure, but examined the different ways in which polyhedra could link via vertices to form chains. He defines the concept of ‘‘structural hierarchy’’ as a general scheme that ties together a certain number of arrangements. An extension of the structural analysis of Moore is found in chapter 6, which is devoted to his systematic study of edge-sharing clusters, deriving the possible arrangements based solely on topological and geometrical principles according to the notions of energy minima and stability (Moore 1974). Chapter 5 deals with the paper by Brown and Shannon (1973), on the empirical bond-valence/ bond-length curves for oxides. A further refinement of the Brown and Shannon approach, into a comprehensive theory that addresses many aspects of the chemical bonding, was developed by Brown (1981), and is presented in chapter 8. Bond-valence analysis of inorganic crystal structures is an essential check on the validity of any structure determination. In his commentary on chapter 8, Hawthorne outlines the critical points introduced by Brown in the bond-valence theory, with interesting application in mineralogy, and presents the bond-valence theory as a molecular orbital theory and as an ionic theory. Chapter 7 is devoted to the paper by L.S. Dent Glasser (1979) on non-existent silicates, emphasizing that the observed arrangements in silicates represent only a small fraction of those topologically possible. Chapter 9 deals with the paper of Hawthorne (1983) on the graphical enumeration of polyhedral clusters. The author developed a ‘‘structural hierarchy’’ hypothesis which has an energetic basis and relates to paragenetic sequences. An example is Bowen’s reaction series shown as a function of the polymerization characteristic of the structure involved. A related topic is covered in chapter 10, which discusses the energetic content of bond topology with reference to the paper by Burdett et al. (1984). The last paper of this collection constituting chapter 11 is devoted to the role of OH and H2O in oxide and oxysalt minerals, based on Hawthorne (1992). The author analysed the roleplayed by (OH) , (H2O)0, (H3O)+ and (H5O2)2+ in controlling bonding topology, topological dimensionality and the role of H2O as a bond-valence transformer, which bears on the, often highly selective, uptake of interstitial cations by environmentally significant minerals. Chapter 12 is the coda, focusing on the prediction of bond topology and of the stoichiometry of stable compounds in a given chemical system. I think that the re-publication of these landmark papers, accompanied by the commentaries of Prof. Hawthorne, will be useful not only for undergraduate or PhD students, but for all structural mineralogists. This collection provides valuable insights into the evolution of structural mineralogy and its wider application to the petrology. As several of the milestone papers collected in this book are published in German journals (Zeitschrift fu ̈r Kristallographie, Neues Jahrbuch fu ̈r Mineralogie Monatshefte), I did a little inquiry and I found that these journals are often not readily available in departmental libraries, and so this is another good reason to have this book in your own library. In conclusion, I warmly recommend this volume to all mineralogists and to Earth sciences libraries.
G. DIEGO GATT
Ultra-fast escape of a deformable jet-propelled body
No full textIn this work a cephalopod-like deformable body that fills an internal cavity with fluid and expels it to propel an escape manoeuvre, while undergoing a drastic external shape change through shrinking, is shown to employ viscous as well as mainly inviscid hydrodynamic mechanisms to power an impressively fast start. First, we show that recovery of added-mass energy enables a shrinking rocket in a dense inviscid flow to achieve greater escape speed than an identical rocket in a vacuum. Next, we extend the shrinking body results of Weymouth & Triantafyllou (J. Fluid Mech., vol. 702, 2012, pp. 470–487) to three-dimensional bodies and show that three hydrodynamic mechanisms must be combined to achieve rapid escape performance in a viscous fluid: added-mass energy recovery; flow separation elimination; and an optimized energy storage and recovery. In particular, we show that the mechanism of separation elimination achieved through rapid body shrinking, coordinated with the mechanism of recovering the initially imparted added-mass energy, is critical to achieving a high escape speed. Hence a flexible, collapsing body can be vastly superior to a rigid-shell jet-propelled body
A Letter from Sir Charles G.D. Roberts (A Personal Memoir)
No full textSkala recounts her first and subsequent meetings with Charles G.D. Roberts whom she met when he was in his late seventies, and she in her teens. Roberts was a man of paradox, an author of emotionally-distanced verse yet a man of strong sentiment. He was a chameleon, a person who was everything to everybody; he played the role of gentle poet, mentor, and editor; he was a husband, father, and friend. He wrote about unique characters, animal or human, and he was quite naturally an elitist, though his "elite" could have been chosen from all ranks of society, and, indeed, from all societies. Also discussed are some of the critical views on Roberts' work, praiseworthy and not, as well as Roberts' own critical assessment of Skala's early verse
Sunitinib treatment exacerbates intratumoral heterogeneity in metastatic renal cancer
No full textThis work was supported by the Chief Scientist Office, Scotland (ETM37; to G.D. Stewart, A.C.P. Riddick, M. Aitchison, and D.J. Harrison), Cancer Research UK (Experimental Cancer Medicine Centre; to T. Powles, London and D.J. Harrison, Edinburgh), Medical Research Council (to A. Laird and D.J. Harrison), Royal College of Surgeons of Edinburgh (to A. Laird), Melville Trust (to A. Laird), Medical Research Council (MC_UU_12018/25; to I.M. Overton), Royal Society of Edinburgh Scottish Government Fellowship cofunded by Marie Curie Actions (to I.M. Overton), Renal Cancer Research Fund (to G.D. Stewart), Kidney Cancer Scotland (to G.D. Stewart) and an educational grant from Pfizer (to T. Powles).Purpose: The aim of this study was to investigate the effect of VEGF targeted therapy (sunitinib) on molecular intratumoral heterogeneity (ITH) in metastatic clear cell renal cancer (mccRCC). Experimental design: Multiple tumor samples (n=187 samples) were taken from the primary renal tumors of mccRCC patients who were sunitinib treated (n=23, SuMR clinical trial) or untreated (n=23, SCOTRRCC study). ITH of pathological grade, DNA (aCGH), mRNA (Illumina Beadarray) and candidate proteins (reverse phase protein array) were evaluated using unsupervised and supervised analyses (driver mutations, hypoxia and stromal related genes). ITH was analysed using intratumoral protein variance distributions and distribution of individual patient aCGH and gene expression clustering. Results: Tumor grade heterogeneity was greater in treated compared to untreated tumors (P=0.002). In unsupervised analysis, sunitinib therapy was not associated with increased ITH in DNA or mRNA. However, there was an increase in ITH for the driver mutation gene signature (DNA and mRNA) as well as increasing variability of protein expression with treatment (p<0.05). Despite this variability, significant chromosomal and transcript changes to key targets of sunitinib, such as VHL, PBRM1 and CAIX, occurred in the treated samples. Conclusions: These findings suggest that sunitinib treatment has significant effects on the expression and ITH of key tumor and treatment specific genes/proteins in mccRCC. The results, based on primary tumor analysis, do not support the hypothesis that resistant clones are selected and predominate following targeted therapy.Peer reviewe
Intensified Protein Structuring for more sustainable foods: Development of the up-scaled Couette Cell for the production of meat replacers
No full textTo meet the increasing need for protein-rich food of an ever growing population, plant-based proteins are being utilized in meat products as replacements for animal-based proteins. Legumes such as soy can serve as an alternative protein source, by featuring both high protein content (36%) and protein functionality (gelation). Nowadays various meat replacement products are commercially available and thus more and more customers are willing to switch their diet to a vegetable-based one. Currently, the most efficient technology for the production of meat replacers is extrusion cooking and new methods of protein structuring (Shear Cell and Couette Cell) have only recently been introduced. These two new technologies were developed based on the principle of applying simple shear flow and heat in the protein mixture. Initially, a device called the Shear Cell was developed featuring a cone-cone design that could structure soy-based mixtures in meat-like products. However, since the Shear Cell design is limited to lab use only, a new technology was developed and presented in this thesis. The Couette Cell concept, which is based on the concentric cylinder principle, has been studied, since it allows for further upscaling at industrially relevant production volumes. The research starts with a proof of concept study by using the lab scaled Couette Cell, which features a volume of 0.14 L and a shearing zone gap size of 5 mm, between the two cylinders (Chapter 2). Applying simple shear and heat at varying process conditions (temperature, time and rotation rate) to a soy-based mixture, has yielded anisotropic structures that resembled meat. In particular, fibrous structures were favoured at temperatures between 90 and 100 °C. The fibrous products with the highest anisotropy indices were further examined and characterized with a set of complementary techniques (Chapter 3). With light microscopy we could observe structure formation over the visible surfaces of the specimens and by using a stain we could distinguish between the different ingredients. According to the texture analysis results, the anisotropy indices of the obtained meat replacer and raw meat (beef) are comparable. We introduced the use of neutron refraction method by utilizing spin-echo small angle neutron scattering (SESANS) to provide a look inside the bulk of the anisotropic meat replacer. It was therefore possible to quantify the number of fibre layers and the orientation distribution of the fibres present inside the specimens. The calculated fibre thickness was in line with the observations obtained with scanning electron microscopy (SEM). Since the Couette Cell concept proved successful and enabled scalable operation, we developed a new up-scaled Couette Cell, which can treat 7 L per batch, 50 times more than the lab-scaled Couette Cell. The detailed design of the up-scaled Couette Cell is discussed in Chapter 4. The up-scaled device allows for production of fibrous meat replacers at industrially relevant scales and opens the possibility of commercial production in an emerging market. The device is comprised of two concentric cylinders with the inner cylinder rotating while both are being heated by means of steam. The unique characteristic feature of the up-scaled Couette Cell is its 30 mm gap size, which is 6 times more than the lab-scaled counterpart. Finally, a parametric study was used to find the optimum process conditions between the process time and rotation rate while maintaining a constant temperature (Chapter 5). This study yielded highly fibrous structures with a characteristic 30 mm thickness, which emulates meat accurately. The Couette Cell concept and the flexibility in its design allow production of meat replacers at proportions currently not available. Additionally, no barriers were found for further upscaling this concept by preferably designing a continuous process.Process and EnergyMechanical, Maritime and Materials Engineerin
G.D. Grebenshikov humane pedagogics
No full textStating the problem. Time is the best measure of creativity evaluation. It ruthlessly and objectively separates the wheat from the chaff. Only real literature can stand the test of time. Georgiy Grebenshikov’s talent was noticed from the very beginning of his creative work. He was highly acknowledged by A.M. Gorkiy, V.K. Korolenko, V.Y. Shishkov, F.M. Shalyapin, I.I. Sikorskiy, N.K. Rerih and others. However his author fate was not always even and smooth. He has spent the most part of his life far from his Motherland. This fact saved the writer from inevitable repressions and at the same time was his tragedy. In one of his letters he admitted that if a dog from his Motherland came, he would kiss it. Immigration has divided his creative work into two periods: Siberian 1906-1920 and Immigration 1920-1956
Theoretical modeling of residue curve maps for a reactive distillation concept for the production of n-propyl propionate
No full textResidue curve maps are theoretically generated to assess the feasibility of a reactive distillation concept for the production of n-propyl propionate (ProPro). This product is a widely used solvent in industry and is synthesized by the heterogeneous catalyzed esterification reaction of 1-propanol (ProOH) and propionic acid (ProAc). The application of reactive distillation may result in higher yields, lower investment and operational costs and inherently safer processing. Thermodynamic and kinetic models are described for the quaternary reactive system, which agree well with experimental data from literature. The vapor-liquid equilibrium is modeled using the ‘Gamma-Phi’-formulation where the activity coefficients are calculated using UNIQUAC and the fugacity coefficients are estimated using the method of Hayden-O’Connell. A pseudo-homogeneous approach is used to describe the reaction kinetics and Arrhenius-type of expressions are obtained for the chemical equilibrium constant and the reaction rate constant. The methodology and mathematical models for the residue curve maps are described for three scenarios: (1) non-reactive, (2) chemical equilibrium and (3) kinetically controlled. These cases show that the topology of the residue curve maps depends on the rate of reaction with respect to the rate of evaporation rate, which is included in the Damköhler (Da) number. Based on the reactive residue curve maps, the reactive distillation concept for the production of ProPro tends to be technically feasible using one single column where an excess of alcohol is used in the feed. The resulting process is able to produce pure ProPro at the bottom and an azeotropic mixture of ProOH and water at the top of the column. The separation of the top products by an additional separation step makes that ProOH can be recycled and high conversion levels can be obtainedIRSProcess and EnergyMechanical, Maritime and Materials Engineerin
G.D. Grebenshikov humane pedagogics
No full textStating the problem. Time is the best measure of creativity evaluation. It ruthlessly and objectively separates the wheat from the chaff. Only real literature can stand the test of time. Georgiy Grebenshikov's talent was noticed from the very beginning of his creative work. He was highly acknowledged by A.M. Gorkiy, V.K. Korolenko, V.Y. Shishkov, F.M. Shalyapin, I.I. Sikorskiy, N.K. Rerih and others. However his author fate was not always even and smooth. He has spent the most part of his life far from his Motherland. This fact saved the writer from inevitable repressions and at the same time was his tragedy. In one of his letters he admitted that if a dog from his Motherland came, he would kiss it. Immigration has divided his creative work into two periods: Siberian 1906-1920 and Immigration 1920-1956
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