A novel desymmetrisation approach towards chiral molecules, using "click" chemistry

Typical ly, the popular cl ick react ion between an alkyne and an azide forms a t riazole in very high yield, but since this process does not produce a stereogenic cent re, i t s use wi th chi ral l igands has not been thoroughly invest igated. Choosing a prochi ral diyne as the start ing mater ial al lows the cl ick process to perform a desymmet risat ion step. Desymmet risat ion of prochi ral molecules using cl ick chemist ry is a method that has ha d l i t t le at tent ion in the past . Herein is descr ibed progress into a novel synthet ic route to chi ral molecules using this process. The f i rst part of this thesis int roduces the concept of chiral i ty, why i t is important , and how molecules wi th chi ral i ty are synthesised. Then, the importance of the cl ick react ion and simi lar react ions are discussed. The second part of this thesis repor ts on the format ion and characterisat ion of the bis-alkyne precursors, which are used in the key cl ick chemist ry step. Next , several azide compounds are discussed, as these are also requi red for the key step. The third part of this thesis is concerned wi th the main cl ick chemist ry step. There are sub-sect ions for the original racemic t rial react ions, as wel l as a series of react ions assessing var ious l igands, culminat ing in a tuning of condi t ions for the best l igand. A general react ion scheme for the project is given below. Next fol lows the fourth part , which consists of some react ions performed in conjunct ion wi th a visi t ing project student . Wh i lst these are not key to my research, they are related to the main aim of a chiral cl ick react ion. The f inal part of this thesis is the experimental sect ion and the appendix

Production of levulinic acid in urban biorefineries

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 81-84).The energy security of the United States depends, most experts agree, on the development of substitute sources of energy for the transportation sector, which accounts for over 93% of the nation's petroleum consumption. Although great strides have been made in the development of electric vehicles and associated generation and transmission platforms, technical and economic considerations dictate that the transportation sector will rely preponderately on organic fuels for the foreseeable future. The U.S. Department of Energy and U.S. Department of Agriculture have therefore indicated that integrated cellulosic biorefineries, whose feedstock is abundant lignocellulosic plant matter rather than scarce starch, are a vital area for research, development, and commercialization. This thesis evaluates the commercial viability of cellulosic biorefineries in and near the nation's urban centers, where significant volumes of carbohydrate feedstock are already concentrated, collected, and hauled as municipal and commercial wastes and therefore available to commercial users at negative cost. The case evaluated is a prospective demonstration-scale facility located in the urban corridor linking New York and Philadelphia, where "tipping fees" received for redirecting urban waste from landfills are the highest in the nation. The chosen conversion platform, a mature technology called the Biofine Process that has not previously been commercialized, uses acid-catalyzed hydrolysis of the carbohydrate feedstock to produce levulinic acid, a noted "platform chemical" that provides three main benefits: (1) convertibility from diverse and heterogeneous carbohydrate feedstocks containing the high moisture levels characteristic of putrescible wastes, (2) high conversion yields using the chosen conversion platform, and (3) a wide variety of downstream synthetic transformations to valuable derivatives, including fuels. Co-products include formic acid and furfural. In order to evaluate the economic underpinnings of such a facility, the chosen conversion platform is described on the basis of publicly available documents and modeled using a novel domain-specific language (DSL) and symbolic solution library developed for this thesis. This software tool is used to determine the dynamic equilibrium conditions of the process flow of the chemical plant, including net throughput and energy consumption. Such a tool is required because the process flow of the chosen conversion platform feeds back on itself by recycling hydrolysate and acid catalyst, mandating simultaneous solution. A financial model is presented on the basis of the equilibrium process model showing that public support for such a project is required at the vital demonstration scale. The significant public policy benefits associated with urban biorefineries that can divert putrescible wastes from landfills are therefore shown in this case to depend on public support. In order to estimate the appropriate level of subsidy, external environmental and security benefits are quantified. A study of past federal funding patterns ultimately shows that this level of funding is unlikely to accrue to urban projects without changes in the rural emphasis of current policy and public administration.by Garth Alexander Sheldon-Coulson.S.M.in Technology and Polic

Characterization and cytotoxicity studies of thiol-modified polystyrene microbeads doped with [(Mo6X8)(NO3)6]2- (X=Cl, Br, I)

Halide octahedral molybdenum clusters [(Mo6X8)L6]n- possess luminescence properties that are highly promising for biological applications. These properties are rather dependent on the nature of both the inner ligands X (i.e. Cl, Br, or I) and the apical organic or inorganic ligands L. Herein, the luminescence properties and the toxicity of thiol-modified polystyrene microbeads (PS-SH) doped with [(Mo6X8)(NO3)6]2- (X=Cl, Br, I) were studied and evaluated using human epidermoid larynx carcinoma (Hep2) cell cultures. According to our data, the photoluminescence quantum yield of (Mo6I8)@PS-SH is significantly higher (0.04) than that of (Mo6Cl8)@PS-SH (6Br8)@PS-SH (6X8)@PS-SH showed that all three types of doped microbeads had no significant effect on the viability and proliferation of the cells

Kearns-sayre syndrome with reduced plasma and cerebrospinal fluid folate

A young woman with Kearns-Sayre syndrome and progressive central nervous system deterioration over 15 years had decreased plasma and cerebrospinal fluid folate levels while receiving phenytoin for a seizure disorder. A muscle biopsy showed a “ragged red fiber” myopathy with reduced muscle carnitine and mitochondrial enzymes. Computed tomographic brain scans showed cerebral white matter hypodensities and bilateral calcification of the basal ganglia. The mechanism for the folate deficiency and altered ratio of plasma to cerebrospinal fluid folate is unknown, but the deficiency may be responsive to replacement therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50301/1/410130620_ftp.pd

A psychology based approach for longitudinal development in cognitive robotics.

A major challenge in robotics is the ability to learn, from novel experiences, new behavior that is useful for achieving new goals and skills. Autonomous systems must be able to learn solely through the environment, thus ruling out a priori task knowledge, tuning, extensive training, or other forms of pre-programming. Learning must also be cumulative and incremental, as complex skills are built on top of primitive skills. Additionally, it must be driven by intrinsic motivation because formative experience is gained through autonomous activity, even in the absence of extrinsic goals or tasks. This paper presents an approach to these issues through robotic implementations inspired by the learning behavior of human infants. We describe an approach to developmental learning and present results from a demonstration of longitudinal development on an iCub humanoid robot. The results cover the rapid emergence of staged behavior, the role of constraints in development, the effect of bootstrapping between stages, and the use of a schema memory of experiential fragments in learning new skills. The context is a longitudinal experiment in which the robot advanced from uncontrolled motor babbling to skilled hand/eye integrated reaching and basic manipulation of objects. This approach offers promise for further fast and effective sensory-motor learning techniques for robotic learning

Conventional versus automated measurement of blood pressure in primary care patients with systolic hypertension: randomised parallel design controlled trial

Objective To compare the quality and accuracy of manual office blood pressure and automated office blood pressure using the awake ambulatory blood pressure as a gold standard