Alkylation of aromatics with diols in superacidic media

Friedel–Crafts alkylation of simple aromatics (benzene, toluene, o-, m- and p-xylene) with various types of diols in the presence of superacidic trifluoromethanesulfonic acid was studied. 1,2- and 1,3-diols were found to bring about only monoalkylation yielding unusual monoalkylated products: bis(1-methyl-2-phenylpropyl) ether was formed in the reaction of 2,3-butanediol, and 2,4-dimethyl-2,4-pentanediol produced mono- and di-tert-butyl-substituted benzenes. Higher diol homologues, in turn, undergo electrophilic cyclialkylative ring closure (cyclialkylation) to form tetralin derivatives with high selectivities and in good yields. Additional primary alkylation processes are monoalkylation to yield alkylbenzenes and the formation of diphenylalkanes. The products thus formed may participate in secondary transformations, which are a second cyclialkylation (formation of octahydroanthracene and -phenanthrene derivatives), isomerization and dehydrogenation. Mechanistic studies with stereoisomeric 2,5-hexanediols point to the involvement of open dicationic intermediates in the alkylation process. This revised version was published online in June 2006 with corrections to the Cover Date.     

Application of Comparative Method for Estimating Microporosity of Porous Solids in Adsorption from Solutions

The concept of a comparative method in terms of the liquid adsorption on solids is presented. This method is based on comparison of the excess adsorption isotherm on a porous solid with that measured on a reference nonporous adsorbent. It is proved that proposed approach gives the possibility for separating a total excess adsorption isotherm into partial isotherms, proper for micro- and mesopores. Several experimental systems are analyzed to illustrate the usefulness of the comparative method for evaluating the surface phase capacity, which presents an important quantity in the study of adsorption from solution in the whole concentration region. The comparative method examined for adsorption systems of microporous active carbons seems to be useful for investigating other porous materials as silica gels, zeolites or metal oxides.     

Self‐Assembled Large Au Nanoparticle Arrays with Regular Hot Spots for SERS

The cost‐effective self‐assembly of 80 nm Au nanoparticles (NPs) into large‐domain, hexagonally close‐packed arrays for high‐sensitivity and high‐fidelity surface‐enhanced Raman spectroscopy (SERS) is demonstrated. These arrays exhibit specific optical resonances due to strong interparticle coupling, which are well reproduced by finite‐difference time‐domain (FDTD) simulations. The gaps between NPs form a regular lattice of hot spots that enable a large amplification of both photoluminescence and Raman signals. At smaller wavelengths the hot spots are extended away from the minimum‐gap positions, which allows SERS of larger analytes that do not fit into small gaps. Using CdSe quantum dots (QDs) a 3–5 times larger photoluminescence enhancement than previously reported is experimentally demonstrated and an unambiguous estimate of the electromagnetic SERS enhancement factor of ≈10⁴ is obtained by direct scanning electron microscopy imaging of QDs responsible for the Raman signal. Much stronger enhancement of ≈10⁸ is obtained at larger wavelengths for benzenethiol molecules penetrating the NP gaps.     

Observation of the radiative transitions between 4d9(2D5/2,3/2)5s2nl and 4d105p(2P

Radiative transitions between the 4d ⁹(² D _5/2,3/2)⁵ s ² nl and 4d ¹⁰5p(² P ₁ ^2,3/2/0 )nl autoionization states of the cadmium atom, representing dielectronic recombination satellites of the laser lines of Cd⁺ ion with λ = 325.0 nm (4d ⁹5s ^{2 2} D _3/2 → 4d ¹⁰5p ² P ₁ ^2/0 ) and λ = 353.6 nm (4d ⁹5s ^{2 2} D _3/2 → 4d ¹⁰5p ² P ₃ ^2/0 ), have been observed for the first time in the regime of electron-ion collisions. The energy dependence of the effective cross sections for the electron-impact excitation of satellite lines has been studied in the interval from 7 to 10 eV. The effective cross sections for the excitation of dielectronic recombination satellites are on the order of ∼10⁻¹⁷ cm², which is comparable with the efficiency of excitation of the main laser lines.     

Model-based angiogenic inhibition of tumor growth using modern robust control method

Cancer is one of the most destructive and lethal illnesses of the modern civilization. In the last decades, clinical cancer research shifted toward molecular targeted therapies which have limited side effects in comparison to conventional chemotherapy and radiation therapy. Antiangiogenic therapy is one of the most promising cancer treatment methods. The dynamical model for tumor growth under angiogenic stimulator/inhibitor control was posed by Hahnfeldt et al. in 1999; it was investigated and partly modified many times. In this paper, a modified version of the originally published model is used to describe a continuous infusion therapy. In order to generalize individualized therapies a robust control method is proposed using H_∞ methodology. Uncertainty weighting functions are determined based on the real pathophysiological case and simulations are performed on different tumor volumes to demonstrate the robustness of the proposed method.     

Information schema constructs for defining warehouse databases of genotypes and phenotypes of system manifestation features

Our long-term objective is to develop a software toolbox for pre-embodiment design of complex and heterogeneous systems, such as cyber-physical systems. The novelty of this toolbox is that it uses system manifestation features (SMFs) for transdisciplinary modeling of these systems. The main challenges of implementation of the toolbox are functional design- and language-independent computational realization of the warehouses, and systematic development and management of the various evolving implements of SMFs (genotypes, phenotypes, and instances). Therefore, an information schema construct (ISC) based approach is proposed to create the schemata of the associated warehouse databases and the above-mentioned SMF implements. ISCs logically arrange the data contents of SMFs in a set of relational tables of varying semantics. In this article we present the ISCs necessary for creation of genotypes and phenotypes. They increase the efficiency of the database development process and make the data relationships transparent. Our follow-up research focuses on the elaboration of the SMF instances based system modeling methodology.     

Magnetic QCA systems

The field-coupled QCA architecture has emerged as a candidate for providing local interconnectivity for nanodevices, and offers the possibility to perform very dense, high speed, and low power computing in an altogether new paradigm. Magnetic interactions between nanomagnets are sufficiently strong to allow room-temperature operation. We are investigating the fabrication and testing of arrays of nanomagnets for this purpose, and have found that by tailoring their shapes, strong coupling can be observed. This paper will present recent work of the Notre Dame group on magnetically coupled QCA.     

Synthesis of trans-4,5-epoxy-(E)-2-decenal and its deuterated analog used for the development of a sensitive and selective quantification method based on isotope dilution assay with negative chemical ionization

The volatile compound trans-4,5-epoxy-(E)-2-decenal (1) was synthesized in two steps with good overall yields. The newly developed method is based on trans-epoxidation of (F)-2-octenal with alkaline hydrogen peroxide followed by a Wittig-type chain elongation with the ylide formylmethylene triphenylphosphorane. For the synthesis of [4,5-²H₂]-trans-4,5-epoxy-(E)-2-decenal (d-1), [2,3-²H₂]-(E)-2-octenal was prepared by reduction of 2-octyn-1-ol with lithium aluminum deuteride and subsequent oxidation of [2,3-²H₂]-(E)-2-octen-1-ol with manganese oxide. Compound d-1 was used as internal standard for the quantification of 1 by isotope dilution assay. Among various mass spectrometry (MS) ionization techniques tested, negative chemical ionization with ammonia as reagent gas gave best results with respect to both sensitivity and selectivity. The detection limit was found to be at about 1 pg of the analyte introduced into the gas chromatography-MS system.     

Calibration of Fluxset sensors for the measurement of spatially strongly inhomogeneous magnetic fields

A procedure developed for the calibration of a magnetic sensor in spatially strongly inhomogeneous magnetic field is presented in this paper. Assuming that the sensor is linear and it does not significantly disturb the magnetic field to be measured, its output signal is approximated as the weighted sum of the field values calculated theoretically around the sensor. The weighting coefficients are obtained by finding the best fit of the actual experimental output and the theoretical prediction of the measured field in the least square sense. Using the presented procedure, sensors can be calibrated for the measurement of spatially strongly inhomogeneous magnetic fields, consequently such sensors can be applied to get the field distribution map of inhomogeneous fields.