Synthesis of porous hematite nanorods loaded with CuO nanocrystals as catalysts for CO oxidation

Porous hematite (α-Fe2O3) nanorods with the diameter of 20-40 nm and the length of 80-300 nm were synthesized by a simple surfactant-assisted method in the presence of cetyltrimethylammonium bromide (CTAB).The α-Fe2O3 nanorods possess a mesostructure with a pore size distribution in the range of 5-12 nm and high surface area,exhibiting high catalytic activity for CO oxidation.CuO nanocrystals were loaded on the surface of porous α-Fe2O3 nanorods by a deposition-precipitation method,and the catalysts exhibited superior activity for catalytic oxidation of CO,as compared with commercial α-Fe2O3 powders supported CuO catalyst.The enhanced catalytic activity was attributed to the strong interaction between the CuO nanocrystals and the support of porous α-Fe2O3 nanorods.     

A Fluorogenic Probe for Cell Surface Phosphatidylserine Using an Intramolecular Indicator Displacement Sensing Mechanism

The detection of externalized phosphatidylserine (PS) on the cell surface is commonly used to distinguish between living, apoptotic, and necrotic cells. The tools of choice for many researchers to study apoptosis are annexin V‐fluorophore conjugates. However, the use of this 35 kDa protein is associated with several drawbacks, including temperature sensitivity, Ca²⁺ dependence, and slow binding kinetics. Herein, a fluorogenic probe for cell surface PS, P‐IID , is described, which operates by an intramolecular indicator displacement (IID) mechanism. An intramolecularly bound coumarin indicator is released in the presence of cell surface PS, leading to a fluorescence “turn‐on” response. P‐IID demonstrates superior performance when compared to annexin V, for both fluorescence imaging and flow cytometry. This allows P‐IID to be used in time‐lapse imaging of apoptosis using confocal laser scanning microscopy and demonstrates the utility of the IID mechanism in live cells.     

Bessel–Gauss beam optical resonator

In a simple picture, a Bessel beam is viewed as a transverse standing wave formed in the interference region between incoming and outgoing conical waves. Based on this interpretation we propose an optical resonator that supports modes that are approximations to Bessel–Gauss beams. The Fox–Li algorithm in two transverse dimensions is applied to confirm the conclusion.     

Modified carbon cloth as positive electrode with high electrochemical performance for vanadium redox flow batteries

Carbon cloth modified by hydrothermal treatment in ammonia water is developed as the positive electrode with high electrochemical performance for vanadium redox flow batteries.The SEM shows that the treatment has no obvious influence on the morphology of carbon cloth.XPS measurements indicate that the nitrogenous functional groups can be introduced on the surface of carbon cloth successfully.The electrochemical performance of V（IV）/V（V） redox couple on the prepared electrode is evaluated with cyclic voltammetry and linear sweep voltammetry measurements.The N-doped carbon cloth exhibits outstanding electrochemical activity and reversibility toward V（IV）/V（V） redox couple.The rate constant of V（IV）/V（V） redox reaction on carbon cloth can increase to 2.27 × 10^-4cm/s from 1.47 × 10^-4cm/s after nitrogen doping.The cell using N-doped carbon cloth as positive electrode has larger discharge capacity and higher energy efficiency compared with the cell using pristine carbon cloth.The average energy efficiency of the cell using N-doped carbon cloth for 50 cycles at 30 m A/cm² is 87.8%,4.3% larger than that of the cell using pristine carbon cloth.It indicates that the N-doped carbon cloth has a promise application prospect in vanadium redox flow batteries.     

An index to measure the ability of first year science students to transfer mathematics

This project aimed to quantitatively measure the ability of first year science students to transfer their mathematical skills and knowledge to a physical context. An instrument used in earlier studies to measure transfer of mathematical knowledge was modified for this project, and tested with 49 student volunteers. This paper presents the Transfer Index, a novel way of measuring the degree of transfer of the students' mathematics skills and knowledge. It is demonstrated that the Transfer Index is a useful way of quantifying transfer and that it has predictive validity in a natural educational setting.     

Cylinder-wall interference effects on finite-length wavy cylinders at subcritical Reynolds number flows

An experimental study was conducted on aspect-ratio of six finite-length wavy cylinders immersed within a Re _D = 2,700 free-stream. Wavelengths of 2 and 4 diameters, as well as wave amplitude of 0.1, 0.2 and 0.3 diameters were used for a comprehensive investigation. Time-resolved particle-image velocimetry measurements and proper orthogonal decomposition analyses show that for the present large wavelength wavy cylinders, vortex-shedding behaviour of high aspect-ratio wavy cylinders observed in past studies can be altered through variations in the aspect-ratio, exact geometric node and saddle locations, as well as the presence of end-walls. This is due to the persistent formation of recirculating regions close to the end-walls under certain wavy cylinder configurations, which affect the distributions of spanwise flows and vortex formation lengths. Vortex-shedding behaviour of smaller-wavelength wavy cylinders has also been observed to be considerably less sensitive to variations in the physical configurations, due to the formation of multiple streamwise vortices at the saddles. The presence of these coherent streamwise vortices is postulated to play a key role in significantly reducing flow-altering effects associated with the end-walls.     

A RECONSIDERATION OF THE PROPERTIES OF A PULSED RUBY LASER IN RELATION TO MICROSURGERY

Abstract— The properties of a pulsed ruby laser beam focused through a triocular microscope were studied in relation to microsurgery. Quantitative studies on 'model tissues' with different absorbencies at 6943 Å revealed that the spot diameter of the focused microbeam was dependent upon several factors. It decreased with (1) a decrease in the absorption by the object at 6943 Å; (2) a decrease in the energy of the microbeam; and (3) an increase in the magnification of the microscope. The existence of the 'tube of effect' in the optical path of the focused micro-beam was realized by irradiating the object at different planes. The depth of the tube of effect increased with (1) increase in laser energy or (2) decrease in magnification. By employing certain plant species ( Spirogyra praetensis Transeau, Ulva lactuca Linnaeus, Porphyra miniata (Lyngbye) C. Agardh and Elodea sp.) the reaction of the protoplasm to the laser microbeam in terms of 'primary damage' and 'secondary damage' was defined. Based on these experimental data the concept of minimal visible spot size in laser microsurgery and its limitations are discussed.     

Competing processes in optical parametric chirped pulse amplification

Optical parametric chirped pulse amplification (OPCPA) has the potential to revolutionise the generation of high power ultrashort optical pulses. In this paper, we present the results of a numerical investigation into processes that potentially compete with OPCPA. Specifically, we examine group velocity dispersion, non-degenerate operation, background noise, pump pulse fluctuations, and compressor error. We also discuss the “local approximation” and show that, in the case of OPCPA, it offers a substantial advantage in computational speed for minimal cost in accuracy. The overall conclusion is that OPCPA is fundamentally robust, and that the processes studied pose a less serious problem than might have been expected.