Can Extensional Flow Rupture Macromolecules in an Electrospinning Process?

The fracture of high molecular weight poly(ethylene oxide) (PEO) chains under extensional stretching during the electrospinning of aqueous solutions was investigated by measuring solution viscosities and monitoring the change of molecular weight. The degree of macromolecular chain fractures in 1.0% polymer solutions increased with the increase in molecular weight. The strain rates for stretching and fracturing of macromolecules are critical for the degradation of polymers along with experimental elongational strain rates. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1051–1054     

Immunomagnetic diffractometry for detection of diagnostic serum markers

We describe an integrated approach for detection of diagnostic markers using in situ assembled optical diffraction gratings in combination with immunomagnetic capture. Folate receptor (FR), a serum protein indicative of various cancers, was chosen as a model system to demonstrate the potential of the method. Magnetic beads coupled to FR antibody were used to capture FR from serum. The FR-bound magnetic beads self-assembled onto microcontact-printed folate-coupled BSA (F-BSA) patterns to form diffraction gratings which served to detect FR by measuring the diffraction intensities caused by laser illumination. The FR-containing beads, upon binding to the F-BSA surface, served as intrinsic signal enhancement agents, circumventing the need for additional enzymatic signal amplification or fluorescent labeling steps. With this approach, a detection sensitivity of 700 fM (20 pg/mL) was achieved. The potential use of this approach in clinical diagnostics was demonstrated by measuring FR concentration in blood samples obtained from cancer patients.     

Ultrafast photonic crystal lasers

We describe recent progress in photonic crystal nanocavity lasers with an emphasis on our recent results on ultrafast pulse generation. These lasers produce pulses on the picosecond scale, corresponding to only hundreds of optical cycles. We describe laser dynamics in optically pumped single cavities and in coupled cavity arrays, at low and room temperature. Such ultrafast, efficient, and compact lasers show great promise for applications in high‐speed communications, information processing, and on‐chip optical interconnects.     

The direct total evaporation (DTE) method for TIMS analysis

The total evaporation (TE) method is an established analytical method for safeguards measurements of uranium and plutonium isotope-amount ratios using thermal ionization mass spectrometry. As fractionation effects are minimized in this analytical method, it is a method of choice in many practical applications that require high accuracy and precision isotope abundance ratio measurements. The speed of signal regulation is a critical parameter for a steady sample evaporation process. Standard TE methods use the data system to read the ion signal and its difference from the target intensity is used to determine the increment in which the filament is heated. The new, hardware-driven proprietary direct total evaporation method uses an analog regulator in the filament power supply with direct feedback of the detector intensity. Only target values are set by the data system initially. The filament heating and sample evaporation process is then carried out by the hardware. The data system just monitors, collects, and calculates the data. Due to the nature of electronic regulation the ion signal is kept stable for the duration of the run until the whole sample is consumed. For routine uranium isotopic analyses of the major isotope-amount ratio n(²³⁵U)/n(²³⁸U) using a modified MAT261 instrument with SPECTROMAT? hardware and software upgrades, precision (relative standard deviation, expressed as a percent) and accuracy (relative difference, expressed as a percent) of 0.05 % are obtained for low enriched and high enriched uranium certified reference materials.     

Ribozyme-mediated signal augmentation on a mass-sensitive biosensor

Mass-based detection methods such as the quartz crystal microbalance (QCM) offer an attractive option to label-based methods; however the sensitivity is generally lower by comparison. In particular, low-molecular-weight analytes can be difficult to detect based on mass addition alone. In this communication, we present the use of effector-dependent ribozymes (aptazymes) as reagents for augmenting small ligand detection on a mass-sensitive device. Two distinct aptazymes were chosen: an L1-ligase-based aptazyme (L1-Rev), which is activated by a small peptide (MW approximately 2.4 kDa) from the HIV-1 Rev protein, and a hammerhead cleavase-based aptazyme (HH-theo3) activated by theophylline (MW = 180 Da). Aptazyme activity was observed in real time, and low-molecular-weight analyte detection has been successfully demonstrated with both aptazymes.     

Polyelectrolytes in thin liquid films

The review addresses the influence of polyelectrolytes on the statics and dynamics of thin liquid films. Both, changes of interfacial and bulk properties, contribute to the overall behaviour of thin films formed from aqueous polyelectrolyte solutions. Therefore, the chapter is separated into two parts: polyelectrolytes at film interfaces and polymers in film bulk.     

Quantum oscillations in confined and degenerate Fermi gases. II. The phase diagram and applications of half-vicinity model

For part I see DOI: 10.1016/j.physleta.2018.02.006. Size and density dependent quantum oscillations appear in Fermi gases under strong confinement and degeneracy conditions. We provide a universal recipe that explicitly separates oscillatory regime from non-oscillatory (stationary) one. A phase diagram representing stationary and oscillatory regimes on degeneracy-confinement space is proposed. Analytical expressions of phase transition interfaces are derived. The critical point, which separates entirely stationary and oscillatory regions, is determined and its dependencies on aspect ratios are examined for anisometric domains. Accuracy of the half-vicinity model and the phase diagram are verified through the quantum oscillations in electronic heat capacity and its ratio to entropy.     

Polarization control and sensing with two-dimensional coupled photonic crystal microcavity arrays

We have experimentally studied polarization properties of the two-dimensional coupled photonic crystal microcavity arrays and observed a strong polarization dependence of the transmission and reflection of light from the structures-effects that can be employed in building miniaturized polarizing optical components. Moreover, by combining these properties with a strong sensitivity of the coupled bands on the surrounding refractive index, we have demonstrated a detection of small refractive-index changes in the environment, which is useful for construction of biochemical sensors.     

The Casimir-like size effects in ideal gases

The wave character of atoms can produce Casimir-like size effects in gases confined in a narrow box. Thus the pressure tensor is not isotropic anymore and size difference becomes a driving force for isothermal diffusion by a permeable wall. Such size effects give rise to “thermosize effects” similar to thermoelectric effects.