Experimental Characterization Data Research Articles

Bmim][OTf] as co-solvent/promoter in room temperature reactivity-based one-pot glycosylation reactions

[bmim][OTf] can promote regio- and chemo-selective glycosylation reactions at room temperature. Furthermore, the applicability to ambient three-component reactivity-based one-pot glycosylation reactions is demonstrated for the synthesis of several trisaccharides.

Novel synthesis of bismuth tungstate hollow nanospheres in water–ethanol mixed solvent

Bi(2)WO(6) hollow nanospheres were prepared in a sacrificial templates approach by converting the reaction medium from aqueous solution to a mixed solvent of water and ethanol.

A Gneralized Frequency-Temperature Viscoelastic Model

The design of passive damping treatments using viscoelastic materials requires both an accurate numerical analysis approach, usually making use of the finite element method, and a realistic means of material description. While the former has been widely studied and several and valuable approaches have become available during the last years, the latter is still an issue requiring additional efforts. The experimental characterization, the data modeling and finally the constitutive models able to be directly used along analytic and numerical analysis, are still important research areas. Several viscoelastic models, able to be directly applied into a finite element analysis either in a time or in a frequency domain analysis, are available and have been widely used during the last years in most of the published work. Despite the general description and straightforward use that such modeling approaches may provide, temperature effect is usually disregarded and isothermal analysis are usually performed. Moreover, this temperature effect is naturally not directly considered as an input parameter for most of the viscoelastic material models and isothermal conditions are also considered in the experimental characterization data analysis. This work presents an extended viscoelastic model, based on well known isothermal models, where the temperature-frequency superposition effect is directly considered. The extended model is applied to the analysis of the experimental data using a data fitting procedure to identify a set of global parameters able to represent the effect of the frequency and the temperature.

A Gneralized Frequency-Temperature Viscoelastic Model

The design of passive damping treatments using viscoelastic materials requires both an accurate numerical analysis approach, usually making use of the finite element method, and a realistic means of material description. While the former has been widely studied and several and valuable approaches have become available during the last years, the latter is still an issue requiring additional efforts. The experimental characterization, the data modeling and finally the constitutive models able to be directly used along analytic and numerical analysis, are still important research areas. Several viscoelastic models, able to be directly applied into a finite element analysis either in a time or in a frequency domain analysis, are available and have been widely used during the last years in most of the published work. Despite the general description and straightforward use that such modeling approaches may provide, temperature effect is usually disregarded and isothermal analysis are usually performed. Moreover, this temperature effect is naturally not directly considered as an input parameter for most of the viscoelastic material models and isothermal conditions are also considered in the experimental characterization data analysis. This work presents an extended viscoelastic model, based on well known isothermal models, where the temperature-frequency superposition effect is directly considered. The extended model is applied to the analysis of the experimental data using a data fitting procedure to identify a set of global parameters able to represent the effect of the frequency and the temperature.

TfOH-catalyzed intramolecular alkyne–ketone metathesis leading to highly substituted five-membered cyclic enones

The intramolecular carbocyclization of tethered alkynyl ketones to five-membered cyclic enones is shown to be catalyzed by trifluoromethanesulfonic acid in MeOH, proceeding in good to excellent yields and with high selectivities.

Iron-catalyzed addition of Grignard reagents to activated vinyl cyclopropanes

A highly regioselective iron-catalyzed addition of branched primary, secondary or tertiary alkyl Grignard reagents to activated vinyl cyclopropanes is described, which likely proceeds by a direct addition mechanism as opposed to single electron transfer or an iron-allyl based process.

Organic polymer composites as robust, non-covalent supports of metal salts

A novel organic polymer composite for the encapsulation of metal catalysts and applications to synthesis are described here.

Anthracene-Fused Porphyrins

This thesis describes the synthesis of a novel family of porphyrins fused to anthracenes, together with investigations into their optical and electrochemical properties, as well as exploring their potential for application in dye-sensitised solar cells. Chapter 1 gives an overview of the structure-property relationships of large planar pi- systems for organic electronic applications. Porphyrins are introduced as suitable building blocks for such systems, and approaches for extending the pi-conjugation of these macrocycles are presented. A literature review of porphyrins fused to aromatic units is presented in Chapter 2, with a focus on the influence of structure on the optoelectronic properties of such systems. The chapter concludes with a summary of my previous work on the synthesis of anthracene-fused porphyrins, and the aims of this project are stated. Chapter 3 describes the syntheses of fully and partially fused bis-anthracene porphyrin monomers and dimers. By varying peripheral substituents, it was possible to solve problems of aggregation encountered for these systems. Fusion of anthracene units to a porphyrin core was found to result in systems displaying strong absorption in the near-IR, small HOMO-LUMO gaps, and low oxidation potentials. Chapter 4 explores the synthesis, crystal structure and optoelectronic properties of a porphyrin fused to four anthracenes, revealing this system to exhibit the longest wavelength absorption of any porphyrin monomer. The synthesis of a liquid crystalline tetra-anthracene-fused porphyrin was proposed, and attempts to synthesise the necessary anthracene precursors were undertaken. Chapter 5 describes the molecular design and synthetic pathway to a mono-anthracene fused porphyrin, and its unfused analogue, for use in liquid electrolyte dye-sensitised solar cells. By varying the metal oxide layer or lithium ion concentration of the device, it was possible to achieve incident photon to current conversion efficiency (IPCE) responses at wavelengths beyond 1050 nm. Chapter 6 details the experimental synthetic procedures and characterisation data for all the compounds synthesised during this project.

Synthesis of Natural-Product-Like Molecules with Over Eighty Distinct Scaffolds

Synthesis of Natural-Product-Like Molecules with Over Eighty Distinct Scaffolds

Zeta potential and electroosmotic mobility in microfluidic devices fabricated from hydrophobic polymers: 1. The origins of charge

This paper combines new experimental data for electrokinetic characterization of hydrophobic polymers with a detailed discussion of the putative origins of charge at water-hydrophobe interfaces. Complexities in determining the origin of charge are discussed in the context of design and modeling challenges for electrokinetic actuation in hydrophobic microfluidic devices with aqueous working fluids. Measurements of interfacial charge are complicated by slip and interfacial water structuring phenomena (see Part 2, this issue). Despite these complexities, it is shown that (i) several hydrophobic materials, such as Teflon and Zeonor, have predictable electrokinetic properties and (ii) electrokinetic data for hydrophobic microfluidic systems is most consistent with the postulate that hydroxyl ion adsorption is the origin of charge.

Preparation and X-ray crystal structure of 2-iodyl-N,N-dialkylaniline oxides: first entry into the heterocyclic system of benziodoxazole

The oxidation of 2-iodo-N,N-dialkylanilines with an excess of dimethyldioxirane in acetone affords 2-iodyl-N,N-dialkylaniline oxides, structural features of which are in agreement with the new heterocyclic system of benziodoxazole.

Fabrication Process for RSFQ/Qubit Systems

We have developed a Nb/Al/AlOx/Nb trilayer process aimed towards integration of RSFQ and qubit circuits. The emphasis is to provide a process enabling RSFQ operation at sub-100 mK temperatures required for qubit operation. In this paper we describe the main properties of the process. We also present experimental characterization data and in particular introduce a method of determining the critical current density by wafer level room temperature measurements.

A highly diastereoselective, catalytic three-component assembly reaction for the synthesis of spiropyrrolidinyloxindoles

Spiropyrrolidinyloxindole compounds are synthesized in moderate to excellent yield via a highly diastereoselective Cu(I)-catalysed three-component assembly reaction of an imine, diazo-compound and substituted olefin dipolarophile.

Hydrophilic Characterization of Automotive Brake Fluid

Abstract This paper presents significant experimental data for hydrophilic characterization of automotive brake fluids. A novel technique is developed for these measurements. Because brake fluid is well known as a hygroscopic fluid, its molecular O-H structure easily allows hydrogen bonding with hydromolecules, e.g., H2O. The moist brake fluid reduces the boiling point and moreover causes the deterioration of the functionality of the brake system. A proximal linear relationship between moisture content and its corresponding resistance for DOT3 brake fluid is found in this study, which uses the signal input of the electronic control unit (ECU) of the brake system. The applied technology of measurement is especially developed in the laboratory, which consists of two functions; the moisture meter and the automatic prewarning system. This instrument changes the controlling conception of a brake system from a passive regular check of brake fluid to an active prewarning for the drivers.

Molecular characterization of a disease associated conformational epitope on GAD65 recognised by a human monoclonal antibody b96.11

Autoantibodies to the 65 kDa isoform of glutamate decarboxylase (GAD65) are associated with type I diabetes and recognise highly conformational epitope(s) that remain to be defined. The human recombinant Fab from mAb b96.11 inhibits binding of most GAD65 antibody positive sera from patients and its epitope has previously been localized to the middle region of GAD65. Recent studies indicate that b96.11 antibody specificity predicts the risk of developing type 1 diabetes in prediabetic individuals. We describe the use homology modelling, protein–protein docking simulations and biopanning of random peptide phage displayed libraries with b96.11 to predict contact amino acids on the interface of GAD65/Fab b96.11 complex. Further analysis by in vitro mutagenesis of GAD65 followed by radioimmunoprecipitation refined the amino acids contributing to the b96.11 epitope. Our studies show an interface characterized by a protruding antibody-combining site centered on the long heavy chain CDR3 loop of Fab b96.11 establishing interactions with the critical residue Phe 344 in the core of the epitope on GAD65, surrounded by charged sites within 375RK 376 and 305DER 307. The epitope requires residues from both middle and the C-terminal domains, and is the first precise definition of an epitope on GAD65. The nature of the b96.11 epitope leads to considerations of potential structural variations for differences in antigenicity between the isoforms GAD65 and GAD67. The study shows the utility of using a combination of in silico techniques and experimental data for molecular characterization and localization of conformational epitopes for which crystal structures are lacking.

New regiospecific isothiazole C–C coupling chemistry

Regioselective palladium catalysed coupling reactions are achieved in good to high yields, starting from either 3,5-dichloro- or 3,5-dibromoisothiazole-4-carbonitriles 1 and 2, providing 3-halo-5-(hetero/aryl, alkenyl and alkynyl)isothiazoles 3, 4, 6-9 from Stille couplings, 3-halo-5-(hetero/arylethynyl)isothiazoles 14-19 from Sonogashira and 5,5'-bi(3-chloroisothiazole-4-carbonitrile) (13) from an Ullmann type coupling. 3,5-Dibromoisothiazole-4-carbonitrile 2 is more reactive than the dichloroisothiazole-4-carbonitrile 1 and effective enough for Stille, Negishi and Sonogashira couplings. 5,5-Bi(3-chloroisothiazole-4-carbonitrile) (13) is prepared by a palladium catalysed Ullmann coupling from 3-chloro-5-iodoisothiazole-4-carbonitrile (11). A variety of 3-substituted isothiazoles (3-substituents = Cl, Br, OMs, OTs and OTf) are less reactive and fail to give successful Suzuki couplings at the isothiazole C-3 position. The 3-iodo-5-phenyl-isothiazole-4-carbonitrile (28), prepared via Sandmeyer iodination, participates successfully in Suzuki, Ullmann type, Stille, Negishi and Sonogashira coupling reactions. All products are fully characterized.

Rapid generation of molecular complexity using “hybrid” multi-component reactions (MCRs): application to the synthesis of α-amino nitriles and 1,2-diamines

Methyleneaziridines can be converted into a wide range of 1,2-diamines and 2-cyanopiperidines in a single operation with the formation of three intermolecular carbon-carbon bonds using a "hybrid" MCR.

Finite element implementation of a generalized Fung-elastic constitutive model for planar soft tissues

Numerical simulations of the anisotropic mechanical properties of soft tissues and tissue-derived biomaterials using accurate constitutive models remain an important and challenging research area in biomechanics. While most constitutive modeling efforts have focused on the characterization of experimental data, only limited studies are available on the feasibility of utilizing those models in complex computational applications. An example is the widely utilized exponential constitutive model proposed by Fung. Although present in the biomechanics literature for several decades, implementation of this model into finite element (FE) simulations has been limited. A major reason for limited numerical implementations are problems associated with inherent numerical instability and convergence. To address this issue, we developed and applied two restrictions for a generalized Fung-elastic constitutive model necessary to achieve numerical stability. These are (1) convexity of the strain energy function, and (2) the condition number of material stiffness matrix set lower than a prescribed value. These constraints were implemented in the nonlinear regression used for constitutive model parameter estimation to the experimental biaxial mechanical data. We then implemented the generalized Fung-elastic model into a commercial FE code (ABAQUS, Pawtucket, RI, USA). Single element and multi-element planar biaxial test simulations were conducted to verify the accuracy and robustness of the implementation. Results indicated that numerical convergence and accurate FE implementation were consistently obtained. The present study thus presents an integrated framework for accurate and robust implementation of pseudo-elastic constitutive models for planar soft tissues. Moreover, since our approach is formulated within a general FE code, it can be straightforwardly adopted across multiple software platforms.

Aminative rearrangement of 2-alkoxy-3,4-dihydro-2H-pyrans: a novel stereocontrolled route to substituted pyrrolidinesElectronic supplementary information (ESI) available: experimental details and characterisation data for all new compounds. See http://www.rsc.org/suppdata/cc/b3/b316554j/

Aziridination of 2-alkoxy-3,4-dihydro-2H-pyrans leads to rearrangement and stereocontrolled formation of 5-alkoxypyrrolidines which may be reduced to pyrrolidines or allylated stereoselectively.

A novel migrative addition reaction of hydrazines to the diketone derivative of C60Electronic supplementary information (ESI) available: experimental procedures and characterisation data; computational procedures and Cartesian coordinates of 3a-I. See http://www.rsc.org/suppdata/cc/b3/b302080k/

A novel addition reaction of an aromatic hydrazine to the diketone derivative of C60 occurs highly regioselectively with an unusual migration of two hydrogen atoms from the hydrazine to the fullerene and affords a fluorescent product having a methylene carbon along the orifice.