An inhomogeneous elliptic complex

We define a 3 term sequenceP of differential operators of mixed type; the first and third operators are 1st order while the second operator is 2nd order.P is always elliptic; it forms a complex ifM is einstein. It was first discussed by Gasqui.P is related to similar complexesC andG discussed by 02 Calabi and Gasqui-Goldschmidt. The index and equivariant index ofP vanish. In dimension 2,P=C⊗s whereS is of Dirac type;C and-S determine the same equivariant index. We study the heat equation asymptotics of the operators ofP; the associated Laplacians do not have scalar leading symbol. Research partially supported by the NSF, NSA, IHES, and Ohio State     

Microchannels filled with diverse micro- and nanostructures fabricated by glancing angle deposition

The integration of porous structures into microchannels is known to enable unique and useful separations both in electrophoresis and chromatography. Etched pillars and other nanostructures have received considerable interest in recent years as a platform for creating microchannels with pores tailored to specific applications. We present a versatile method for integration of three-dimensionally sculptured nano- and micro-structures into PDMS microchannels. Glancing angle deposition was used to fabricate nanostructures that were subsequently embedded in PDMS microchannels using a sacrificial resist process. With this technique, an assortment of structures made from a wide selection of materials can be integrated in PDMS microchannels; some examples of this versatility, including chiral and chevron nanostructures, are demonstrated. We also present a working device made using this process, separating 6/10/20 kbp and 10/48 kbp DNA mixtures in a DNA fractionator containing GLAD-deposited SiO(2) vertical posts as the separating medium. The separation mechanism was verified to resemble that found in prior fractionation devices, using total internal reflection fluorescence microscopy. GLAD fabrication enables insertion of three-dimensional structures into microchannels that cannot be fabricated with any existing techniques, and this versatility in structural design could facilitate new developments in on-chip separations.     

Nanoengineered polymeric S-layers based capsules with targeting activity

Nanostructured polymeric capsules are regarded as highly promising systems with different potential applications ranging from drug delivery, biosensing and artificial cells. To fully exploit this potential, it is required to produce bio-activated stable and biocompatible capsules. To this purpose, in present work we proposed the combination of the layer-by-layer self assembly method with bacterial S-layer technology to fabricate stable and biocompatible polymeric capsules having a well defined arrangement of functional groups allowing the covalent attachment of antibody molecules. Hollow microcapsules were obtained by the layer-by-layer self assembly of oppositely charged polyelectrolytes onto colloidal particles, followed by removal of the cores at acidic pH. S-layers were crystallized onto the shell of the obtained capsules. Quartz crystal microbalance was used to characterize the crystallization process onto planar surfaces. S-layer containing capsules were investigated by atomic force microscopy. Immunoenzymatic tests were performed to assess the effective modification of the S-layer with antibody molecules both on planar surfaces and on hollow capsules. Fluorescent microscopy was employed to visualize the presence of the antibody molecules onto the capsule shell and immunological tests used to assess the bioactivity of the immobilized antibodies. Finally, the in vitro cytotoxicity of fabricated S-layer containing capsules was studied. The obtained results demonstrated the possibility to fabricate bio-activated S-layer containing capsules with improved features in terms of biocompatibility.     

Nonmonotonous variation of DNA angular separation during asymmetric pulsed field electrophoresis

Asymmetric pulsed field electrophoresis within crystalline arrays is used to generate angular separation of DNA molecules. Four regimes of the frequency response are observed, a low frequency rise in angular separation, a plateau, a subsequent decline, and a second plateau at higher frequencies. It is shown that the frequency response for different sized DNA is governed by the relation between pulse time and the reorientation time of DNA molecules. The decline in angular separation at higher frequencies has not previously been analyzed. Real‐time videos of single DNA molecules migrating under high frequency‐pulsed electric field show the molecules no longer follow the head to tail switching, ratchet mechanism seen at lower frequencies. Once the pulse period is shorter than the reorientation time, the migration mechanism changes significantly. The molecule reptates along the average direction of the two electric fields, which reduces the angular separation. A freely jointed chain model of DNA is developed where the porous structure is represented with a hexagonal array of obstacles. The model qualitatively predicts the variation of DNA angular separation with respect to frequency.     

Configurational Properties of N,N′-Dimethyl-1,3-Diazacyclohexane and Its Analogues Containing P and As Atoms: A Hybrid-DFT Study and NBO Interpretation

Abstract

The configurational properties of N,N′-dimethyl-1,3-diazacyclohexane (1), N,N′-dimethyl-1,3-diphosphacyclohexane (2), and N,N′-dimethyl-1,3-diarsenacyclohexane (3) have been analyzed by means of hybrid density functional theory (B3LYP/6-311+G**)–based method and NBO interpretation. The NBO analysis of donor–acceptor (bond?antibond) interactions revealed that the calculated generalized anomeric effects (GAE) between the equatorial ee-ae, ea-aa, and ee-aa configurations decrease from compound 1 to compound 3. Contrary to the decrease of the GAE values for ee-ea configurations, the ea configuration stability increases from compound 1 to compound 3. This could be explained reasonably by the decrease of the nonbonded steric repulsions (by lengthening of the C?M bond lengths increase from compound 1 to compound 3) between the ee, ea, and aa configurations from compound 1 to compound 3. The correlations between the GAE, Wiberg bond indexes (WBI), natural bond orders (NBOs), dipole moments, orbital integrals, structural parameters, and Gibbs free energy difference (G _ee–G _ea, G _ea–G _aa G _ee–G _aa) values (i.e., ΔG _ee-ea, ΔG _ea-aa, ΔG _ee-aa) values between the ee, ea, and aa configurations of compounds 1–3 have investigated.

GRAPHICAL ABSTRACT     

Monophosphoramide derivatives: synthesis and crystal structure,theoretical and experimental studies of their biological effects

Molecular Diversity - Synthesizing new chemical compounds and studying their biological applications have been important issues in scientific research. In this investigation, we synthesized and...     

Synthesis of some novel tetraimidazolium salts derived from diphenyl- and dimethylglycolurils

Several new tetrabromo compounds based on diphenyl- and dimethylglycolurils were synthesized. Sequential treatment of these compounds with imidazole, methyl iodide, and sodium tetrafluoroborate gave their corresponding tetra imidazolium salts. Some of these compounds because of their low melting points can be registered as a potential and new class of ionic liquids. Correspondence: Mehdi Bakavoli, Department of Chemistry, School of Sciences, Ferdowsi University, Mashhad 91375-1436, Iran.     

Synthesis and performance evaluation of chitosan/zinc oxide nanocomposite as a highly efficient adsorbent in the removal of reactive red 198 from water

In this study, Chitosan and Chitosan-zinc oxide (ZnO) nanocomposite were prepared and applied as a low-cost adsorbent with high adsorption capacity for removing reactive red 198 (RR 198) dye from contaminated water. After preparation, it was characterized using FT-IR, XRD, and SEM. The effect of pH, temperature, time, adsorbent amount, and initial dye concentration were investigated in the removal efficiency of RR 198. The maximum adsorption capacity (q_m) obtained from the Langmuir equation was 172.41 mg/g in adsorbent dose of 0.1 g/L, pH: 4, temperature of 25°C, adsorption time of 40 min. The thermodynamic parameters demonstrated the spontaneous and endothermic nature of the adsorption process. Due to the high efficiency of chitosan/ZnO nanocomposite in removal of RR 198 from water and advantages such as high adsorption capacity, simple synthesis, and easy application, it can be used as an effective method in the removal of RR 198 from water.