Building a Better Halide Receptor: Optimum Choice of Spacer,Binding Unit,and Halosubstitution

Quantum calculations are used to measure the binding of halides to a number of bipodal dicationic receptors, constructed as a pair of binding units separated by a spacer group. A number of variations are studied. A H atom on each binding unit (imidazolium or triazolium) is replaced by Br or I. Benzene, thiophene, carbazole, and dimethylnaphthalene are considered as spacer groups. Each receptor is paired with halides F^?, Cl^?, Br^?, and I^?. Substitution with I on the binding unit yields a large enhancement of binding, as much as 13 orders of magnitude; a much smaller increase occurs for substitution with Br. Imidazolium is a more effective binding agent than is triazolium. Benzene and dimethylnaphthalene represent the best spacers, followed by thiophene and carbazole. F^? binds much more strongly than do the other halides, which obey the order Cl^?>Br^?>I^?.     

Refrigerated shelf-life evaluation of high pressure processed,raw and sous vide cooked lobster

ABSTRACT

High pressure processing (HPP) and sous vide may increase the shelf-life of high value seafood products without the use of additives. This study investigated the effects of 150MPa or 350MPa for 10min on microbial, sensory, and physicochemical qualities of raw and subsequently sous vide cooked (65°C) lobster tails during 28 days of refrigerated storage. Raw lobster pressurized at 350MPa or sous vide cooked maintained significantly lower microbial counts, total volatile base nitrogen, and biogenic amine levels. Due to off-odors, 90% and 60% of sensory respondents rejected the control and 150MPa raw samples, respectively, by day 7, while 70% rated the 350MPa samples as still acceptable on day 28. For cooked lobster, only 20% of the respondents rejected any samples by day 28. Moderate HPP conditions were effective in extending refrigerated shelf-life of vacuum-packaged raw lobster tails. However, HPP pretreatment did not contribute to additional shelf-life extension for sous vide cooked products.     

Competitive Halide Binding by Halogen Versus Hydrogen Bonding: Bis‐triazole Pyridinium

The binding of F^?, Cl^?, Br^?, and I^? anions by bis‐triazole‐pyridine (BTP) was examined by quantum chemical calculations. There is one H atom on each of the two triazole rings that chelate the halide via H bonds. These H atoms were replaced by halogens Cl, Br, and I, thus substituting H bonds by halogen bonds. I substitution strongly enhances the binding; Br has a smaller effect, and Cl weakens the interaction. The strength of the interaction is sensitive to the overall charge on the BTP, rising as the binding agent becomes singly and then doubly positively charged. The strongest preference of a halide for halogenated as compared to unsubstituted BTP, as much as several orders of magnitude, is observed for I^?. Both unsubstituted and I‐substituted BTP could be used to selectively extract F^? from a mixture of halides.     

Efficient in vivo selection of a novel tumor-associated peptide from a phage display library

We developed a screening procedure to identify ligands from a phage display random peptide library that are selective for circulating bone marrow derived cells homing to angiogenic tumors. Panning the library on blood outgrowth endothelial cell suspension in vitro followed by in vivo selection based on homing of bone marrow-bound phage to angiogenic tumors, yielded the peptide QFPPKLTNNSML. Upon intravenous injection phage displaying this peptide homed to Lewis lung carcinoma (LLC) tumors in vivo whereas control phage did not localize to tumor tissue. Phage carrying the QFPPKLTNNSML peptide labeled with ??Cu radionuclide when administered intravenously into a tumor bearing mouse was detected noninvasively with positron emission tomography (PET) around the tumor. These proof-of-principle experiments demonstrate the ability of the QFPPKLTNNSML peptide to deliver payload (radiolabeled phage conjugates) in vivo to sites of ongoing angiogenesis and point to its potential clinical utility in a variety of physiologic and pathologic processes where neovascular growth is a critical component.     

The Principle of Equivalence and the Twin Paradox

No Heading The canonical twin paradox is explained by making a correct use of the principle of equivalence. The role of the principle of equivalence is to provide a physical agent i.e gravity which can supply the required extra aging to the rocket-bound sibling during its acceleration phase through a gravitational time-offset effect. We follow an approach where a novel variation on the twin paradox is used to connect gravity with the desynchronization in the clocks of two spatially distant, identically accelerated observers. It is shown that this approach removes certain drawbacks of an earlier effort which claims to exploit the equivalence principle in explaining the differential aging in the paradox. * Author to whom all correspondences should be made.     

Modelling of a closed two-dimensional reactor bounded by a wavy wall

In this paper, we propose a model for a two-dimensional closed reactor bounded by a wavy wall. The left, right and top walls of the reactor are assumed to be flat surfaces while the bottom wall is a wavy surface. In order to formulate a model for such a reactor, we introduce a coordinate transformation into the dimensionless equations of a rectangular closed domain. Then the resulting equations illustrate the phenomena for a closed reactor bounded by a wavy wall. We solve these equations using the finite difference method. The astonishing results are that the intensity of streamlines and the maximum temperature within the reactor significantly increase with an increase of the number of waves in the bottom wall, the amplitude of waves and the Frank-Kamenetskii number. Converse characteristics are observed for higher values of the enlargement of a wave. Moreover, larger Rayleigh number induces stronger vortices in the flow field and reduces the maximum temperature. The Nusselt number at the bottom wavy wall is found to increase for higher values of the Frank-Kamenetskii number and the amplitude of a wave. A transition from the steady-state to the oscillatory convection is identified for a certain value of the Frank-Kamenetskii number. However, for a low value of the Rayleigh number, there occurs a transition from the steady-state to an explosion for increasing value of the Frank-Kamenetskii number. Results also demonstrate that the critical value of the Frank-Kamenetskii number, for which a transition from the steady-state to the oscillatory convection occurs, is higher for increasing values of the number of waves, the enlargement of a wave and the amplitude of a wave.     

A set-covering model for optimizing selection of portfolio of microcontrollers in an automotive supplier company

The sourcing decisions of microcontrollers in automotive industries are complex to manage largely due to the increasing complexity of products requirements, multiple suppliers, and the nature of microcontroller pricing structures. This paper presents a set-covering model that allows the user to select the most economical microcontrollers that meet all the critical product requirements while minimizing the total cost. The optimization process is carried out in two phases. The first phase deals with the construction of a buildable combination matrix by mapping out the critical product requirements against the microcontroller specifications. In the second phase, the model makes an optimal assignment of microcontrollers to each feasible or buildable product by utilizing economies of scales offered by large microcontroller volumes. Lot size constraints are used to handle the step function in the microcontrollers pricing structure. A case study from Visteon Corporation is used to demonstrate the application of the model. Pilot implementation of the model shows a potential saving of nearly two millions over a 4-year planning horizon.     

Zirconium (IV), Thorium (IV) and Dioxouranium (VI) Complexes of Dibasic Tridentate Schiff Bases

Dibasic tridentate Schiff bases obtained by the condensation of O -aminobenzoic acid with salicyldehyde and its 5-chloro and 5-bromo derivatives were synthesised and used to pracipitate Zr(IV), Th(IV) and UO₂(VI) metals as complexes. The 1: 1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility measurements by Gouy method show, these complexes to be monormeic and diamagnetic. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type Zr(OH)₃L.H₂O₂ Th(OH)₂ L.H₂O and UO₂L.H₂O are formed having solvent molecule in co-ordination with metal ion.     

Numerical solution of a steady natural convection flow from a vertical plate with the combined effects of streamwise temperature and species concentration variations

This paper concerns the investigation of steady thermosolutal natural convection from a vertical plate with the combined effect of streamwise sinusoidal variations of both the surface temperature and the species concentration about their respective constant means. The governing boundary layer equations are reduced to nonsimilar form, and these are solved by the stream-function formulations, and by the subsequent application of the Keller box method. The effects of varying the governing nondimensional physical parameters are obtained in terms of the isolines of temperature, iso-species concentration and the streamlines. An asymptotic solution for large values of X, the distance from the leading edge, has also been obtained. It has been found that the two-term asymptotic analysis and the numerical results obtained from Keller-box method are in excellent agreement.     

Tailoring the properties of thermoplastic starch by blending with cinnamyl alcohol and radiation processing: An insight into the competitive grafting and scission reactions

The present paper focuses on the effects of electron beam (EB) irradiation on thermoplastic materials based on destructurized starch including glycerol and water as plasticizers to assess the potentiality of cinnamyl alcohol as reactive additive capable of counterbalancing the degradation of the polysaccharide by inducing interchain covalent linkages. The tensile properties at break of test specimens of controlled composition submitted to EB irradiation at doses ranging from 50 to 200 kGy revealed the presence of competitive chain scission and bridging in samples containing cinnamyl alcohol at a relative concentration of 2.5% with regard to dry starch. The occurrence of crosslinking under particular conditions was evidenced by gel fraction measurements. The treatment under radiation was also applied to model blends including maltodextrin as a model for starch and the other ingredients to gain an insight into the radiation induced mechanisms at the molecular level. The presence of cinnamyl alcohol is found to limit degradation. Size exclusion chromatography and gel fraction allowed to monitor the effects and confirmed unambiguously the attachment of UV-absorbing chromophores onto the maltodextrin main chain. The combination of the obtained results demonstrates the possibility of altering in a favorable way the tensile properties of plasticized starch by applying high energy radiation to properly formulated blends including aromatic compounds like cinnamyl alcohol.