Miniature open channel scrubbers for gas collection

An open channel scrubber is proposed as a miniature fieldable gas collector. The device is 100 mm in length, 26 mm in width and 22 mm in thickness. The channel bottom is rendered hydrophilic and liquid flows as a thin layer on the bottom. Air sample flows atop the appropriately chosen flowing liquid film and analyte molecules are absorbed into the liquid. There is no membrane at the air-liquid interface: they contact directly each other. Analyte species collected over a 10 min interval are determined by fluorometric flow analysis or ion chromatography. A calculation algorithm was developed to estimate the collection efficiency a priori; experimental and simulated results agreed well. The characteristics of the open channel scrubber are discussed in this paper from both theoretical and experimental points of view. In addition to superior collection efficiencies at relatively high sample air flow rates, this geometry is particularly attractive that there is no change in collection performance due to membrane fouling. We demonstrate field use for analysis of ambient SO₂ near an active volcano. This is basic investigation of membraneless miniature scrubber and is expected to lead development of an excellent micro-gas analysis system integrated with a detector for continuous measurements.     

Effect of introduction of heterocyclic moieties into polymer backbone on gas transport properties of fluorinated poly(ether imide) membranes

The effects of incorporation of heterocyclic moieties into fluorinated poly(ether imide) membranes on their gas transport properties were investigated. Four novel fluorinated poly(ether imide) (PEI) membranes were prepared from four different bis(ether amine)s namely, 4,4-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]biphenyl (BAQP); 1,4-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl] benzene (BATP); 2,6-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]pyridine (BAPy) and 2,5-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]thiophene (BATh), and a fluorinated dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane (6FDA) as a common dianhydride. Gas transport properties of these membranes were measured to investigate the effect of chemical structure on gas permeation and diffusion processes over four different gases (e.g., CH₄, N₂, O₂ and CO₂) at different temperatures (e.g., 35, 45 and 55 °C) at an applied pressure of 3.5 bar. It has been found that at 35 °C the permselectivities of BAPy and BATh based polymeric membranes (6.4 and 6.6, respectively) toward O₂ relative to N₂ are higher in comparison to BAQP and BATP (5.5 and 5.3, respectively) containing PEI membranes. The permeability coefficient of CO₂ for BAPy and BATh (51.92 and 45.31, respectively at 35 °C) based PEI membranes were observed to be much higher than BAQP and BATP based membranes (36.61 and 33.51, respectively at 35 °C) with comparable selectivity values of CO₂ relative to CH₄. All these membranes exhibit higher CO₂/CH₄ selectivity than those of common glassy polymers e.g., cellulose acetate, polysulfone and polycarbonate. The order of permeability of these gases was found as CO₂ > O₂ > N₂ > CH₄. The temperature dependency of permeation and diffusion processes enables to calculate the activation energies of the permeation and diffusion processes for these four different gases through four PEI membranes.     

Ensemble effects in Cu/Au ultrasmall nanoparticles control the branching point for C1 selectivity during CO2 electroreduction

Bimetallic catalysts provide opportunities to overcome scaling laws governing selectivity of CO₂ reduction (CO₂R). Cu/Au nanoparticles show promise for CO₂R, but Au surface segregation on particles with sizes ≥7 nm prevent investigation of surface atom ensembles. Here we employ ultrasmall (2 nm) Cu/Au nanoparticles as catalysts for CO₂R. The high surface to volume ratio of ultrasmall particles inhibits formation of a Au shell, enabling the study of ensemble effects in Cu/Au nanoparticles with controllable composition and uniform size and shape. Electrokinetics show a nonmonotonic dependence of C1 selectivity between CO and HCOOH, with the 3Au:1Cu composition showing the highest HCOOH selectivity. Density functional theory identifies Cu₂/Au(211) ensembles as unique in their ability to synthesize HCOOH by stabilizing CHOO* while preventing H₂ evolution, making C1 product selectivity a sensitive function of Cu/Au surface ensemble distribution, consistent with experimental findings. These results yield important insights into C1 branching pathways and demonstrate how ultrasmall nanoparticles can circumvent traditional scaling laws to improve the selectivity of CO₂R.

Bimetallic catalysts provide opportunities to overcome scaling laws governing C1 selectivity of CO₂ reduction (CO₂R).     

Tensor Complementarity Problems with Finite Solution Sets

Journal of Optimization Theory and Applications - In this paper, we first extend the concept of non-degenerate matrices to tensors and we then study the finiteness properties of the solution set of...     

Highly sensitive method for the determination of JI-101, a multi-kinase inhibitor in human plasma and urine by LC-MS/MS-ESI: method validation and application to a clinical pharmacokinetic study

A highly sensitive, rapid assay method has been developed and validated for the estimation of JI-101 in human plasma and urine using LC-MS/MS-ESI in the positive-ion mode. The assay procedure involves extraction of JI-101 and alfuzosin (internal standard, IS) from human plasma/urine with a solid-phase extraction process. Chromatographic resolution was achieved on two Zorbax SB-C(18) columns connected in series with a PEEK coupler using an isocratic mobile phase comprising acetonitrile-0.1% formic acid in water (70:30, v/v). The total run time was 2.0 min. The MS/MS ion transitions monitored were 466.20 → 265.10 for JI-101 and 390.40 → 156.10 for IS. The method was subjected to rigorous validation procedures to cover the following: selectivity, sensitivity, matrix effect, recovery, precision, accuracy, stability and dilution effect. In both matrices the lower limit of quantitation was 10.0 ng/mL and the linearity range extended from ~10.0 to 1508 ng/mL in plasma or urine. The intra- and inter-day precisions were in the ranges 1.57-14.5 and 6.02-12.4% in plasma and 0.97-15.7 and 8.66-10.2% in urine. This method has been successfully applied for the characterization of JI-101 pharmacokinetics in cancer patients.     

Trifluoromethyl acting as stopper in [2]rotaxane

A modified dumbbell obtained by replacing one of the phenyl groups of the dibenzylammonium with a strong electron-withdrawing trifluoromethyl group templated the synthesis of the smallest [2]rotaxane reported so far. The trifluoromethyl group not only enhances the templating effect of the dumbbell but also acts as the stopper to prevent dethreading of a [20]crown ether macrocycle.     

Frequency-selective absorbance detection: Refractive index and turbidity compensation with dual-wavelength measurement

A frequency-selective absorbance detection approach and its applications are described. First, a digital signal processor-lock-in amplifier (DSP-LIA)-based absorbance detector was evaluated. Compared to a simple operational amplifier (TL082CP)-based detector, the DSP-LIA-based detector showed lower noise levels, but the relative advantage was reduced under very low photocurrent levels (down to few nA). A 7 cm pathlength flow cell with this commercial LIA-based detector exhibited excellent Beer's law linearity (r² = 0.9999) and a noise level of 7 micro absorbance units (μAU). The limit of detection (LOD, S/N = 3) for methyl orange (MO) was 7 nM with this detector. Finally, as a more affordable alternative to an LIA, a balanced demodulator integrated circuit chip was used to fabricate a dual wavelength-frequency-selective LED-based absorbance detector. This device successfully compensated refractive index (RI) effect and turbidity effect in test flow systems. The LOD for MO with this system was 8 nM.     

Palladium catalyzed atom-economic synthesis of functionalized 9-(diarylmethylene)-9H-fluorenes using triarylbismuths in one-pot bis-coupling process

An efficient palladium catalyzed atom-economic synthesis of functionalized 9-(diarylmethylene)-9H-fluorenes has been accomplished in one-pot bis-coupling process using triarylbismuths as organometallic reagents. These bis-couplings in 1 hour short reaction time afforded various 9-(diarylmethylene)-9H-fluorenes in good to high yields.     

Spectroscopic and docking studies of the binding of two stereoisomeric antioxidant catechins to serum albumins

The interactions of two stereoisomeric antioxidant flavonoids, catechin (C) and epicatechin (EC) with bovine serum albumin (BSA) and human serum albumin (HSA), have been investigated by steady state and time resolved fluorescence, phosphorescence, circular dichroism (CD), FTIR and protein–ligand docking studies. The steady-state fluorescence studies indicate a single binding site for both the ligands. FTIR spectra suggest that in both the albumins, C and EC stabilize the α-helix at the cost of a corresponding loss in the β-sheet structure. CD studies have been carried out using (±)C, and both the epimers (+)C and (?)C. The low temperature phosphorescence and protein–ligand [(+), (?) and (±) forms of C and EC] docking studies indicate that the ligands bind in the proximity of Trp 134 of BSA and Trp 214 of HSA, thereby changing their solvent accessible surface areas (ASA). Asn 158 and Glu 130 side chains are found to be within the hydrogen bonding distance from the phenolic –OH groups of C and EC in the case of BSA complex. C and EC are located within the binding pocket of sub-domain IIa of HSA.     

F-theory,Seiberg-Witten curves and $ \mathcal{N} = {2} $ dualities

Journal of High Energy Physics - A geometrical form of the supersymmetry conditions for D-branes on arbitrary type II supersymmetric backgrounds is derived, as well as the associated BPS bounds....