An oscillation criterion for forced half-linear differential equations with mixed nonlinearities

In this note, a new oscillation criterion for forced half-linear second order differential equations with mixed nonlinearities is obtained by using a generalized Riccati transformation. The result of this note generalizes and improves some previous results in the literature.     

A modified coupled map car following model and its traffic congestion analysis

Based on the coupled map car following model which was presented by Konishi et al. [Konishi KJ, Kokame H, Hirate K. Phys Rev E 1999;60:4000-7.] (for short, KKH), a modified coupled map car following model is proposed. In this model two successive vehicles’ headway distances in front of the considered one are incorporated in the optimal velocity (for short, OV) function. The stability condition is given for the change of the speed of the preceding vehicle on the base of the control theory. The control scheme in KKH model is applied to the modified model and the feedback gains are determined. Comparison between the modified model and KKH model is carried out. And the corresponding numerical simulation results show that the temporal behavior obtained by our model is better than that by KKH model. The simulation results are in good agreement with the theoretical analysis.     

Total synthesis of bistramide A and its 36(Z) isomers: differential effect on cell division, differentiation, and apoptosis

The total synthesis of bistramide?A and its 36(Z),39(S) and 36(Z),39(R) isomers shows that these compounds have different effects on cell division and apoptosis. The synthesis relies on a novel enol ether-forming reaction for the spiroketal fragment, a kinetic oxa-Michael cyclization reaction for the tetrahydropyran fragment, and an asymmetric crotonylation reaction for the amino acid fragment. Preliminary biological studies show a distinct pattern of influence of each of the three compounds on cell division, differentiation, and apoptosis in HL-60 cells, thus suggesting that these effects are independent activities of the natural product.     

Characterization of different FAD-dependent glucose dehydrogenases for possible use in glucose-based biosensors and biofuel cells

In this study, different flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenases (FADGDHs) were characterized electrochemically after “wiring” them with an osmium redox polymer [Os(4,4′-dimethyl-2,2′-bipyridine)₂(PVI)₁₀Cl]⁺ on graphite electrodes. One tested FADGDH was that recently discovered in Glomerella cingulata (GcGDH), another was the recombinant form expressed in Pichia pastoris (rGcGDH), and the third was a commercially available glycosylated enzyme from Aspergillus sp. (AspGDH). The performance of the Os-polymer “wired” GDHs on graphite electrodes was tested with glucose as the substrate. Optimal operational conditions and analytical characteristics like sensitivity, linear ranges and current density of the different FADGDHs were determined. The performance of all three types of FADGDHs was studied at physiological conditions (pH 7.4). The current densities measured at a 20 mM glucose concentration were 494 ± 17, 370 ± 24, and 389 ± 19 μA cm⁻² for GcGDH, rGcGDH, and AspGDH, respectively. The sensitivities towards glucose were 2.16, 1.90, and 1.42 μA mM⁻¹ for GcGDH, rGcGDH, and AspGDH, respectively. Additionally, deglycosylated rGcGDH (dgrGcGDH) was investigated to see whether the reduced glycosylation would have an effect, e.g., a higher current density, which was indeed found. GcGDH/Os-polymer modified electrodes were also used and investigated for their selectivity for a number of different sugars.     

F-Actin reassembly during focal adhesion impacts single cell mechanics and nanoscale membrane structure

Focal adhesions play an important role in cell spreading,migration,and overall mechanical integrity.The relationship of cell structural and mechanical properties was investigated in the context of focal adhesion processes.Combined atomic force microscopy(AFM) and laser scanning confocal microscopy(LSCM) was utilized to measure single cell mechanics,in correlation with cellular morphology and membrane structures at a nanometer scale.Characteristic stages of focal adhesion were verified via confocal fluorescent studies,which confirmed three representative F-actin assemblies,actin dot,filaments network,and long and aligned fibrous bundles at cytoskeleton.Force-deformation profiles of living cells were measured at the single cell level,and displayed as a function of height deformation,relative height deformation and relative volume deformation.As focal adhesion progresses,single cell compression profiles indicate that both membrane and cytoskeleton stiffen,while spreading increases especially from focal complex to focal adhesion.Correspondingly,AFM imaging reveals morphological geometries of spherical cap,spreading with polygon boundaries,and elongated or polarized spreading.Membrane features are dominated by protrusions of 41-207 nm tall,short rods with 1-6 μm in length and 10.2-80.0 nm in height,and long fibrous features of 31-246 nm tall,respectively.The protrusion is attributed to local membrane folding,and the rod and fibrous features are consistent with bilayer decorating over the F-actin assemblies.Taken collectively,the reassembly of F-actin during focal adhesion formation is most likely responsible for the changes in cellular mechanics,spreading morphology,and membrane structural features.     

Fast and reversible CO2 quartz crystal microbalance response of vinylimidazolium‐based poly(ionic liquid)s

A series of poly(ionic liquid)s (pILs) based on the 1‐vinyl‐3‐hexylimidazolium polymerizable cation and on the bis(trifluoromethylsulfonyl)imide, nonafluoro‐1‐butanesulfonate, dodecylbenzenesulfonate, heptadecafluorooctanesulfonate, and 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11‐heptadecafluoroundecanoate anions have been synthesized and characterized. Their sorption/desorption response towards CO₂ has been tested through quartz crystal microbalance investigations. The obtained results show that all of the pILs here reported are featured by peculiar CO₂ sorption properties as they display fast and linear response, reversibility without any memory effect, and reproducibility, suggesting that anion plays a key role in determining sensitivity. Copyright © 2011 John Wiley & Sons, Ltd.     

TR-FRET-based duplex immunoassay reveals an inverse correlation of soluble and aggregated mutant huntingtin in huntington's disease

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by the amplification of a polyglutamine stretch at the N terminus of the huntingtin protein. N-terminal fragments of the mutant huntingtin (mHtt) aggregate and form intracellular inclusions in brain and peripheral tissues. Aggregates are an important hallmark of the disease, translating into a high need to quantify them in?vitro and in?vivo. We developed a one-step TR-FRET-based immunoassay to quantify soluble and aggregated mHtt in?cell and tissue homogenates. Strikingly, quantification revealed a decrease of soluble mHtt correlating with an increase of aggregated protein in primary neuronal cell cultures, transgenic R6/2, and HdhQ150 knock-in HD mice. These results emphasize the assay's efficiency for highly sensitive and quantitative detection of soluble and aggregated mHtt and its application in high-throughput screening and characterization of HD models.     

A pH-responsive fluorescent probe and photosensitiser based on a self-quenched phthalocyanine dimer

A self-quenched zinc(ii) phthalocyanine dimer linked with an acid-sensitive ketal unit has been prepared, which can be activated in an acidic environment (pH = 5.0-6.5) as a result of the cleavage of the ketal linker and separation of the phthalocyanine units, resulting in enhanced fluorescence emission and singlet oxygen production.     

Improved vector quantization scheme for grayscale image compression

This paper proposes an improved image coding scheme based on vector quantization. It is well known that the image quality of a VQ-compressed image is poor when a small-sized codebook is used. In order to solve this problem, the mean value of the image block is taken as an alternative block encoding rule to improve the image quality in the proposed scheme. To cut down the storage cost of compressed codes, a two-stage lossless coding approach including the linear prediction technique and the Huffman coding technique is employed in the proposed scheme. The results show that the proposed scheme achieves better image qualities than vector quantization while keeping low bit rates.     

Energy-loss function of TTF-TCNQ

We investigate the energy-loss function for a previously developed model of quasi-one-dimensional metals with two one-dimensional electron bands per donor and acceptor chains and the three-dimensional long-range Coulomb electron-electron interaction within the random phase approximation. It is essentially influenced by two hybridized collective modes which result from the strong coupling of the intraband plasmon and the interband dipolar modes. Our calculations show that the spectral weights of the renormalized plasmon and the dipolar mode dominate within the long wavelength limit, while for large longitudinal wave vectors the intraband electron-hole quasi-continuumgains some experimentally observable spectral weight as the second mode approaches it. The function obtained is brought into correspondence with the data of the quasi-one-dimensional organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) obtained from electron energy-loss spectroscopy (EELS) measurements.