In Vitro and In Vivo Sequestration of Methamphetamine by a Sulfated Acyclic CB[n]-Type Receptor

We report the synthesis of two new acyclic sulfated acyclic CB[n]-type receptors ( TriM0 and Me₄TetM0 ) and investigations of their binding properties toward a panel of drugs of abuse ( 1 – 13 ) by a combination of ¹H NMR spectroscopy and isothermal titration calorimetry. TetM0 is the most potent receptor with K_a≥10⁶ M⁻¹ toward methamphetamine, fentanyl, MDMA and mephedrone. TetM0 is not cytotoxic toward HepG2 and HEK 293 cells below 100 μM according to MTS metabolic and adenylate kinase release assays and is well tolerated in vivo when dosed at 46 mg kg⁻¹. TetM0 does not inhibit the hERG ion channel and is not mutagenic based on the Ames fluctuation test. Finally, in vivo efficacy studies show that the hyperlocomotion of mice treated with methamphetamine can be greatly reduced by treatment with TetM0 up to 5 minutes later. TetM0 has potential as a broad spectrum in vivo sequestrant for drugs of abuse.     

Quantitative analysis of surface plasmon interaction with silver nanoparticles

The present insight into plasmon effects on the nanoscale seems sufficiently advanced to allow the development of surface-plasmon-polariton- (SPP-) based optical devices. Therefore quantitative information describing SPP phenomena is required. We investigate a SPP beam splitter constituted by silver nanoparticles on a silver thin film, fabricated by electron-beam lithography. We acquire quantitative information on the beam splitter performance by monitoring SPP leakage radiation, yielding SPP reflection, transmission, and scattering efficiencies.     

From Iron to Copper: The Effect of Transition Metal Catalysts on the Hydrogen Storage Properties of Nanoconfined LiBH4 in a Graphene-Rich N-Doped Matrix

Incipient wetness impregnation was employed to decorate two N-doped graphene-rich matrixes with iron, nickel, cobalt, and copper nanoparticles. The N-doped matrix was wetted with methanol solutions of the corresponding nitrates. After agitation and solvent evaporation, reduction at 800 °C over the carbon matrix promoted the formation of nanoparticles. The mass of the metal fraction was limited to 5 wt. % to determine if limited quantities of metallic nanoparticles catalyze the hydrogen capture/release of nanoconfined LiBH₄. Isotherms of nitrogen adsorption afforded the textural characterization of the matrixes. Electronic microscopy displayed particles of definite size, evenly distributed on the matrixes, as confirmed by X-ray diffraction. The same techniques assessed the impact of LiBH₄ 50 vol. % impregnation on nanoparticle distribution and size. The hydrogen storage properties of these materials were evaluated by differential scanning calorimetry and two cycles of volumetric studies. X-ray diffraction allowed us to follow the evolution of the material after two cycles of hydrogen capture-release. We discuss if limited quantities of coordination metals can improve the hydrogen storage properties of nanoconfined LiBH₄, and which critical parameters might restrain the synergies between nanoconfinement and the presence of metal catalysts.     

Mobility of protein through a porous membrane

The electrophoretic mobility of proteins in membrane pores has been investigated experimentally. When the size of the protein is small relative to the pore size, the protein mobility is identical to the free protein mobility. As the pore radius approaches the protein radius the mobility of the protein is significantly reduced. This phenomenon has been explained in terms of electrokinetic theory. Using a method of reflections, and taking into account the effect of the back-flow, an approximation has been developed for the average mobility in a closed system of a spherical particle moving under electrophoresis parallel to the axis of a cylindrical pore. This approximation assumes that the surface potential of the particle is low, and is valid for arbitrary double layer thickness relative to particle size, provided that there is minimal overlap between the double layers at the pore surface and around the particle. It is also predicted that when the protein and the membrane have surface potentials of the same sign, there can be a significant increase in protein mobility for medium-sized pores.     

Stable Finiteness of Group Rings in Arbitrary Characteristic

We show that every (discrete) group ring D[G] of a free-by-amenable group G over a division ring D of arbitrary characteristic is stably finite, in the sense that one-sided inverses in all matrix rings over D[G] are two-sided. Our methods use Sylvester rank functions and the translation ring of an amenable group.     

Nanoparticles of the novel coordination polymer KBi(H2O)2[Fe(CN)6]·H2O as a potential contrast agent for computed tomography

An aqueous synthetic procedure for preparing nanoparticles of the novel potassium bismuth ferrocyanide coordination polymer KBi(H(2)O)(2)[Fe(CN)(6)]·H(2)O is reported. The crystal structure of this coordination polymer is determined through X-ray powder diffraction using the bulk materials. The stability, cytotoxicity, and potential use of such nanoparticles coated with PVP as a CT contrast agent are investigated.     

Gas phase attachment of water and methanol to Ag(I) complexes with alpha-amino acids in an ion trap mass spectrometer

Electrospray ionization was used to generate gas phase complexes of Ag+ with selected alpha-amino acids. Following storage (isolation without collisional activation) in an ion trap mass spectrometer, the mass spectra produced from the complexes of Ag+ with alpha-amino acids such as alanine, valine and tert-leucine contained peaks consistent with the formation of water or methanol molecule adduct ions. The same adduct ions were not present, however, in the mass spectra generated from the Ag+ complexes with phenylalanine, tyrosine and tryptophan following isolation and storage under similar conditions. For those complexes that showed reactivity, the uptake of water and methanol increased with longer storage times in the ion trap. A preliminary molecular modeling study using phenylalanine demonstrated that the aromatic ring coordinates the Ag+ ion, and the interaction between the metal ion and pi-system, in part, is assumed to prohibit the binding of water or methanol during isolation in the gas phase. This conclusion is supported by a comparison of the adduct formation by the Ag+ complexes with phenylalanine, 4-fluorophenylalanine and alpha-aminocyclohexanepropionic acid. In addition, collision induced dissociation experiments involving the Ag+ complexes of phenylalanine, tyrosine and tryptophan suggest that limiting the coordination of the Ag ion by the complexing molecule (i.e. by loss of a coordinating functional group and/or change in structure due to dissociation) results in the binding of a water or methanol molecule during storage in the ion trap. Surprisingly, the bare Ag+ ion, when trapped and stored under identical experimental conditions, formed neither adduct species, suggesting that the attachment of water or methanol may be due to interactions with a molecular orbital within the Ag+/molecule complex.     

Morphological control of MgxZn1−xO layers grown on Ga:ZnO/glass substrates for photovoltaics

Mg_xZn_1?xO has been used in various photovoltaic cells because its energy bandgap can be tailored by controlling the Mg composition in this ternary compound. The Mg_xZn_1?xO layers with different surface morphologies including two-dimensional (2-D) films and one-dimensional (1-D) nanostructures are preferred for conventional p–n junction solar cells and polymer–inorganic hybrid solar cells, respectively. The Mg_xZn_1?xO layers are sequentially grown on Ga-doped ZnO (GZO) transparent conductive electrode using metalorganic chemical vapor deposition (MOCVD). The effect of the buffer layers on Mg_xZn_1?xO surface morphology is investigated. It is observed that Mg_xZn_1?xO deposited at ～500 °C on a low-temperature (～250 °C) ZnO buffer layer is in the form of 2-D dense and smooth films, whereas, on a high-temperature (～520 °C) ZnO buffer layer is in the form of 1-D nanostructures. Based on the structure characterization results, a growth mechanism in terms of nucleation and texturing is proposed to explain the buffer layer effect.     

Quantum mechanical effects in internal photoemission THz detectors

The variation in spectral shape around the threshold frequencies between model and experimental responsivity spectra in heterojunction interfacial workfunction internal photoemission (HEIWIP) infrared detectors was investigated. This is attributed to the loss of photoexcited carriers, within the escape cone, prior to photoemission. The energy dependent transmission of excited carriers is incorporated to the existing photoemission model to show that emission around the threshold frequency is reduced considerably by quantum mechanical reflection of photoexcited carriers as observed in experimental results. In the new model, the photoemission of carriers become bias dependent.