Preparation and thermal decomposition of zinc/copper trimellitates and pyromellitates

The aim of this research was to prepare and characterise zinc, copper and mixed zinc/copper trimellitates (1,2,4-benzene tricarboxylates) and pyromellitates (1,2,4,5- benzene tetracarboxylates). The characterisation included a study of the thermal decomposition for selected salts. The literature is reviewed, discussing the synthesis, structural properties, and thermal decompostions of carboxylate salts. This review highlights the growing interest in benzene carboxylates, and a summary of the applications of such salts is given at the end of the review. The preparative route investigated in the work reported here involved reacting zinc/copper hydroxycarbonate, (Zn(_x)Cu(_1-x))(_n)(CO(_2))(_p)(OH)q, with the carboxylic acid. This preparation was chosen in an attempt to overcome problems encountered during previous projects, which are discussed in the introduction. The preparation and characterisation of zinc/copper hydroxycarbonates were studied, concentrating on the preparation of single phase products. The hydroxycarbonate route was successful in producing single metal and mbced metal salts of trimellitic and pyromellitic acid. Limits of the solid solution series were deduced for the mixed metal carboxylates. Three trimelitate crystal structures, Zn(_2)OH(C(_6)H(_3)(COO)(_3)) . 2H(_2)O, ZnCuOH(C(_6)H(_3)(COO)(_3)) . 2H(_2)O, CuH(C(_6)H(_3)(COO)(_3)) . 2.5H(_2)O, and one pyromellitate structure, ZnH(_2)(C(_6)H(_2)(COO)(_4)) . 6H(_2)O, were determined. The trimellitate structures were all polymeric layers, with the anion bridging between the metal sites. The pyromellitate had an ionic structure with [Zn(H(_2)O)(_6)](^2+) cations and [H(_2)(C(_6)H(_2)(COO)(_4))](^2)- anions. The dianion had very strong, intramolecular H-bonding. Using these and other crystal structures, it was possible to deduce a correlation between IR absorptions for carboxylate groups and the type of carboxylate coordination. The thermal decomposition of the metal salts was studied. An investigation was undertaken using DSC and temperature programmed decomposition to deduce the mechanism for the thermal decomposition of selected salts. The effect of the cation ratio (for the mixed metal salts) upon the decomposition was also studied. The work reported here has shown the success of the hydroxycarbonate route for the formation of polycarboxylate salts. Characterisation for a number of new zinc/copper salts is reported. A study of the thermal decompositions for selected salts has deduced the mechanism and factors affecting the decomposition

Catalytic constructive deoxygenation of lignin-derived phenols: new C-C bond formation processes from imidazole-sulfonates and ether cleavage reactions

Funding: UK Engineering and Physical Sciences Research Council (EPSRC)As part of a programme aimed at exploiting lignin as a chemical feedstock for less oxygenated fine chemicals, several catalytic C-C bond forming reactions utilising guaiacol imidazole sulfonate are demonstrated. These include the cross-coupling of a Grignard, a non-toxic cyanide source, a benzoxazole, and nitromethane. A modified Meyers reaction is used to accomplish a second constructive deoxygenation on a benzoxazole functionalised anisole.Publisher PDFPeer reviewe

Chromista

The concept of chromists, at its most expansive, includes the heterokonts (stramenopiles), alveolates, rhizarians, heliozoans, telonemians, haptophytes and cryptophytes. There is mounting evidence that this grouping is not valid. Even in the narrowest sense (the heterokonts), chromists include very diverse forms, exhibiting a great variety of trophic mechanisms. This great diversity in form and feeding make it difficult to identify any unifying features, but molecular phylogenetic studies have shown that this group of organisms is indeed monophyletic. The distribution of morphological characters over reconstructed trees allows for the identification of potential synapomorphic characters that have been secondarily lost or modified across the group. These include a combination of mitochondria with tubular cristae; the biflagellate heterokont condition; and, if photosynthetic, then with chlorophyll c, girdle lamellae and four membranes around the chloroplast, the outer continuous with the nuclear envelope. Heterotrophy appears to be ancestral but is also occasionally a derived state from autotrophic forms.Web of Scienc

Re-estimation of argon isotope ratios leading to a revised estimate of the Boltzmann constant

In 2013, NPL, SUERC and Cranfield University published an estimate for the Boltzmann constant [1] based on a measurement of the limiting low-pressure speed of sound in argon gas. Subsequently, an extensive investigation by Yang et al [2] revealed that there was likely to have been an error in the estimate of the molar mass of the argon used in the experiment. Responding to [2], de Podesta et al revised their estimate of the molar mass [3]. The shift in the estimated molar mass, and of the estimate of kB, was large: -2.7 parts in 106, nearly four times the original uncertainty estimate. The work described here was undertaken to understand the cause of this shift and our conclusion is that the original samples were probably contaminated with argon from atmospheric air.
 In this work we have repeated the measurement reported in [1] on the same gas sample that was examined in [2, 3]. However in this work we have used a different technique for sampling the gas that has allowed us to eliminate the possibility of contamination of the argon samples. We have repeated the sampling procedure three times, and examined samples on two mass spectrometers. This procedure confirms the isotopic ratio estimates of Yang et al [2] but with lower uncertainty, particularly in the relative abundance ratio R38:36.
 Our new estimate of the molar mass of the argon used in Isotherm 5 in [1] is 39.947 727(15) g mol-1 which differs by +0.50 parts in 106 from the estimate 39.947 707(28) g mol-1 made in [3]. This new estimate of the molar mass leads to a revised estimate of the Boltzmann constant of kB = 1.380 648 60 (97) × 10−23 J K−1 which differs from the 2014 CODATA value by +0.05 parts in 106.&#13

Space of slower time, optimism, and contemplation

Thesis (S.B. in Art and Design)--Massachusetts Institute of Technology, Dept. of Architecture, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 63).We stand at the edge of a period of great evolution within human civilization. Renowned inventor, Ray Kurzweil, in his book, The Singularity is Near, predicts that in the next 100 years, we will make 20,000 years of technological progress at year 2000 rates. In other words, that will be the equivalent of 1000 20th centuries in 100 years. This is due to the explosive nature of exponential growth. He also pinpoints an instant when the so-called technological singularity is reached. After this point, technological progress occurs at an essentially vertical rate. He places this around the year 2040. The changes that are to come are positive, inevitable, and completely natural. We should embrace technological progress while not forgetting the basic psychological and spiritual needs of human beings. While all of this progress is to our benefit, constant stimulation can lead to blindness to the universe around us. This blindness does not refer to knowledge. True, we know exponentially more each year, but we also grow increasingly scornful of learning that does not revolve around facts, of pure spiritual wonder at the universe. We scorn downtime and silence as useless and wasteful. We need to regain a positive sense of the word silence (as opposed to definition of emptiness). We need spaces where we are able to stop and simply let our minds idly consider the universe around us. We need spaces that exist outside of contemporary high-paced urban life. We need to feel part of the environment of the universe, in synch with infinite and ever-modulating universe rhythms. We need spaces of slower time, optimism, and contemplation. We can create these types of spaces through a deep understanding of Earth Rhythms, the infinitely changing variables that interact to create our constantly modulating experience of Planet Earth. The architect can be thought of an Earth Composer, someone who decides which environmental phenomena to accentuate. Architecture can be a responsive performance that interacts with the natural world, carrying on a two-way conversation with its environment. The building can be thought of as an infinitely varying performance, a performance that exists as a direct performance to an audience, an internal dialogue with itself, and an interactive performance with human beings. Finally, architecture can be thought of as a holistic system with both technological and biological elements, in which the two are indistinguishable from one another.by Stuart Gavin Ruedisueli.S.B.in Art and Desig