How a single stretched polymer responds coherently to a minute oscillation in fluctuating environments: An entropic stochastic resonance

Within the cell, biopolymers are often situated in constrained, fluid environments, e.g., cytoskeletal networks, stretched DNAs in chromatin. It is of paramount importance to understand quantitatively how they, utilizing their flexibility, optimally respond to a minute signal, which is, in general, temporally fluctuating far away from equilibrium. To this end, we analytically study viscoelastic response and associated stochastic resonance in a stretched single semi-flexible chain to an oscillatory force or electric field. Including hydrodynamic interactions between chain segments, we evaluate dynamics of the polymer extension in coherent response to the force or field. We find power amplification factor of the response at a noise-strength (temperature) can attain the maximum that grows as the chain length increases, indicative of an entropic stochastic resonance (ESR). In particular for a charged chain under an electric field, we find that the maximum also occurs at an optimal chain length, a new feature of ESR. The hydrodynamic interaction is found to enhance the power amplification, representing unique polymer cooperativity which the fluid background imparts despite its overdamping nature. For the slow oscillatory force, the resonance behavior is explained by the chain undulation of the longest wavelength. This novel ESR phenomenon suggests how a biopolymer self-organizes in an overdamping environment, utilizing its flexibility and thermal fluctuations.     

Conductivity of ITO film amplified by multi‐step ion beam‐treatment on PET layers at room temperature

In this paper, we investigate poly‐crystal indium tin oxide (ITO) film produced by a multi‐step ion beam treatment on polyethylene terephthalate (PET) at room temperature. In the process of ITO film deposition by a sputtering method, we perform an ion beam treatment after some quantity of ITO deposition is complete, and this process is carried out repeatedly until the required film thickness is achieved. X‐ray diffraction indicates that the ITO film deposited by our multi‐step ion beam treatment has an almost poly‐crystal structure with a morsel of amorphous structure in the PET layers. As a supplementary measurement, a contact angle method shows that the poly‐crystal structure is due to a surface charge effect. Consequently, the electrical conductivity of the ITO film (resistivity measurement error bar < 0.7%) with the multi‐step ion beam treatment is eight times higher than that of single‐treated ITO film, due to this poly‐crystal structure. Copyright © 2012 John Wiley & Sons, Ltd.     

Use of MDLC-DIGE and LC-MS/MS to identify serum biomarkers for complete remission in patients with acute myeloid leukemia

The response criteria for complete remission (CR) in acute myeloid leukemia (AML) are currently based on morphology and blood cell counts. However, these criteria are insufficient to establish a diagnosis in cases with poor quality bone marrow (BM) samples demonstrating a loss of cellular morphology. We investigated whether the sera of patients contained biomarkers that indicate disease response status. First, we performed multidimensional liquid chromatography-differential gel electrophoresis (MDLC-DIGE) to generate protein profiles of two pooled, paired serum samples from patients who had achieved CR; one collected at diagnosis (PreCR) and the other collected after chemotherapy (CR). Then, with the biomarker candidates found, ELISA was carried out for individual PreCR and CR samples, and for other verification sets including nonremission (NR) patients and normal samples. We selected two proteins, complement factor H (CFH) and apolipoprotein H (ApoH), with dye (Cy) ratios showing greater than 2.0-fold differences between the pooled samples. ELISA showed that CFH and ApoH are useful for distinguishing between the recovered (CR and normal) and nonrecovered (PreCR, PreNR, and NR) states in AML (p <0.001). We successfully applied a protein profiling technology of MDLC-DIGE and LC-MS/MS to discover two biomarkers for CR which needs further validation for a clinical setting.     

Kinetic Study of Empty Fruit Bunch Using Hot Liquid Water and Dilute Acid

Empty fruit bunch (EFB), a residual product of the palm plantation, is an attractive biomass for biorefinery. As xylan is susceptible to high temperature pretreatment, it is important to setup a proper pretreatment condition to maximize the sugar recovery from EFB. Kinetic parameters of mathematical models were obtained in order to predict the concentration of xylose, glucose, furfural, and acetic acid in the hydrolysate and to find production conditions of xylose. We investigated the kinetics of hot liquid water and dilute sulfuric acid hydrolysis over a 40-min period using a self-designed setup by measuring the concentrations of released sugars (xylose, glucose) and degradation products (acetic acid and furfural). The reaction was performed within the range 160～180 °C, under reaction conditions of various concentration of sulfuric acid (0.1～0.2%) and 1:7 solid-liquid ratio in a batch reactor. The kinetic constants can be expressed by the Arrhenius equation with the activation energy for the hydrolysis of sugar and decomposition of sugar. The activation energy of xylose was determined to be 136.2187 kJ mol(-1).     

Effect of temperature and humidity on coarsening behavior of Au nanoparticles embedded in liquid crystalline lipid membrane

Coarsening behavior of the Au nanoparticles produced by thermal evaporation of Au onto a liquid crystalline lipid (1,2-dioleoyl-3-trimethylammonium-propane, DOTAP) membrane was investigated by subjecting the nanoparticle-embedded DOTAP membrane to two different annealing conditions (at 100 °C under no humidity and at 20 °C and 80% relative humidity). Although the coarsening rate was relatively slow because of the low temperature (from 5.6 nm in the as-deposited state to ~7 nm after 30 h), it was identified that at 100 °C without humidity the Au nanoparticles resulted in shape refinement whereas the high humidity at 20 °C induced self-organization of the nanoparticles into a monolayer. It was also found that annealing in both cases tended to segregate the lipid molecules from the nanoparticle array and forced the nanoparticles into a tighter area. In the case of the high-humidity sample, the lipid segregation eventually led to extensive coalescence of the Au nanoparticles.     

Effect of antimony doping on the low‐temperature performance of solution‐processed indium oxide thin film transistors

The effects of antimony (Sb) doping on solution‐processed indium oxide (InO_x) thin film transistors (TFTs) were examined. The Sb‐doped InSbO TFT exhibited a high mobility, low gate swing, threshold voltage, and high I_ON/OFF ratio of 4.6 cm²/V s, 0.29 V/decade, 1.9 V, and 3 × 10⁷, respectively. The gate bias and photobias stability of the InSbO TFTs were also improved by Sb doping compared to those of InO_x TFTs. This improvement was attributed to the reduction of oxygen‐related defects and/or the existence of the lone‐pair s‐electron of Sb³⁺ in amorphous InSbO films. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Edge-state magnetism in hydrogenated armchair carbon nanotubes

We have investigated the antiferromagnetic edge states in hydrogenated carbon nanotubes by using the density functional theory calculations. The total energy difference between the antiferromagnetic and ferromagnetic states, corresponding to the exchange energy gain stabilizing the antiferromagnetic state, changes by an order of magnitude by controlling the hydrogen adsorption pattern and is nearly independent of the nanotube size for a properly chosen pattern, indicating that the antiferromagnetic edge states in the real size nanotubes can be realized at high temperatures. The coexisting zigzag and bearded edges in the hydrogenated CNTs are believed to enhance the exchange energy gain.     

Three-dimensional nanostructured carbon nanotube array/PtRu nanoparticle electrodes for micro-fuel cells

We have fabricated three-dimensional (3D) nanostructured carbon nanotube (CNT) array/PtRu nanoparticle (with the average molar percentage (26%) of Ru) electrodes using anodic aluminum oxide (AAO) templates for micro-fuel cells. 3D nanostructured CNT array was used to support PtRu nanoparticles to enhance the utilization efficiency of Pt. The 3D nanostructured CNT array/PtRu electrodes show the excellent catalytic activity and electrochemical stability of electro-oxidation of methanol. Their anodic current density is 10 times as high as that of PtRu thin-films, which could be explained in terms of the high specific surface area of 3D nanostructured CNT array supporting films and the uniform distribution of PtRu nanoparticles.     

A Selective Fluoroionophore Based on BODIPY‐functionalized Magnetic Silica Nanoparticles: Removal of Pb2+ from Human Blood

Get the lead out : The title fluorescence receptor exhibits a high affinity and selectivity for Pb²⁺ over competing metal ions in water (see picture) with an overall emission change of approximately 8‐fold at the emission maximum for Pb²⁺. The fluorescence receptor can remove 96 % of 100 ppb Pb²⁺ from human blood, and can be useful and effective for the selective and rapid removal of Pb²⁺ in vivo.

     

Bioinspired Colorimetric Detection of Calcium(II) Ions in Serum Using Calsequestrin‐Functionalized Gold Nanoparticles

Seeing is sensing : Calsequestrin (CSQ) functionalized gold nanoparticles undergo calcium‐dependent CSQ polymerization, which results in a clear color change (see picture) together with precipitation. The sensing system is specific for Ca²⁺ ions and the differences between normal and disease‐associated abnormal (hypercalcemia) Ca²⁺ ion levels in serum can be distinguished with the naked eye.