Versatile laser microfabrication techniques for lab-on-chip devices in general and uranium analysis in particular

In a plethora of microfabrication processes available now-a-days, one needs to choose the best possible option suitable for the job on-hand. This paper discusses three versatile approaches to fabricate microchips for lab-on-chip (LOC) applications in general and uranium analysis in water samples as a specific case. Laser-direct patterning succeeded by soft lithography, laser micropatterning followed by HF etching and micromilling have been demonstrated which not only suit the objective of uranium detection but also for most of the LOC applications. The different techniques elaborated enable development of LOCs in polymers as well as glass with a depth ranging from few microns to 100 μm or higher while squeezing the reaction lengths of ～10 cm on a 20 mm × 32 mm chip. This development equips one to design and develop more complicated LOC devices to take advantage of their hastened reaction cycle with minimal waste in terms of capital and maintenance cost.     

Picosecond nonlinear optical properties of cuprous oxide with different nano-morphologies

Cuprous oxide nanoclusters, microcubes and microparticles were successfully synthesized by a simple co-precipitation method. Phase purity and crystallinity of the samples were studied by using X-ray powder diffraction. Transmission electron microscopy (TEM) images show different morphologies like nanoclusters, microcubes and microparticles. For linear and nonlinear optical measurements, the as-synthesized Cu₂O with different morphologies were dispersed in isopropanol solution. The absorption spectrum recorded in the visible regions shows peaks that depend on the morphology of the particles and the peak shifts towards red region as one goes from nanoclusters to microparticles. Simple open-aperture Z-scan technique is used to measure nonlinear optical properties of cuprous oxide at 532 nm, 30 ps excitation at 10 Hz repetition rate. Cuprous oxide nanoclusters show reverse saturable absorption (RSA) behaviour, the microcubes and microparticles at a similar concentration exhibit saturable absorption (SA) type of behaviour at lower peak intensities and exhibit RSA within SA at higher peak intensities. The results show that the transition from SA to RSA can be ascribed to the two-photon absorption (TPA) process.     

Main injector particle production experiment at Fermilab

The main injector particle production (MIPP) experiment at Fermilab uses particle beams of charged pions, kaons, proton and antiproton with beam momenta of 5?C90 GeV/c to measure particle production cross-sections of various nuclei including liquid hydrogen, MINOS target and thin targets of beryllium, carbon, bismuth and uranium. The physics motivation to perform such cross-section measurements is described here. Recent results on the analysis of NuMI target and forward neutron cross-sections are presented here. Preliminary cross-section measurements for 58 GeV/c proton on liquid hydrogen target are also presented. A new method is described to correct for low multiplicity inefficiencies in the trigger using KNO scaling.     

Polarized light

Following the recent work of Chandleret al on quasi probability distributions for spin-1/2 particles, we show that polarized light can be interpreted in terms of trivariate probability distributions in two different ways by choosing the variates to correspond to (i) the co-ordinates on the Poincare sphere, (ii) the components of the spin operator of the photon. In either case, it is shown that the Margenau-Hill procedure leads to probability mass functions while the Wigner-Weyl approach leads to probability density functions and the well-known Stokes parameters are also realised as appropriate averages with respect to these distribution functions.     

On dominator colorings in graphs

A dominator coloring of a graph G is a proper coloring of G in which every vertex dominates every vertex of at least one color class. The minimum number of colors required for a dominator coloring of G is called the dominator chromatic number of G and is denoted by ?? _d (G). In this paper we present several results on graphs with ?? _d (G)?=???(G) and ?? _d (G)?=???(G) where ??(G) and ??(G) denote respectively the chromatic number and the domination number of a graph G. We also prove that if ??(G) is the Mycielskian of G, then ?? _d (G)?+?1?????? _d (??(G))?????? _d (G)?+?2.     

Soliton-induced supercontinuum generation in liquid-filled photonic crystal fibre

We aim to study the nonlinear optical phenomena with ultra-broadband radiation in photonic crystal fibre (PCF). While PCFs with cores made from different glasses are well studied in previous works, in this paper, it is planned to investigate the dynamics of nonlinear processes of supercontinuum generation (SCG) in liquid-filled PCF (LCPCF) to understand the physical phenomena of femtosecond pulse propagation, particularly, the temporal and spectral changes of the pulse propagating through specific PCFs. Since the CS₂-filled LCPCF has complex nonlinear phenomena, we intend to analyse the role of saturable nonlinear response and slow nonlinear response on SCG in detail. For the physical explanation, soliton fission and modulational instability techniques will be implemented to investigate the impact of slow nonlinear response and saturable nonlinear response respectively, in SCG process.     

Kopsia Singapurensis提取物对酸性介质中低碳钢的缓蚀效应(英文)

The influence of the alkaloid extract of Kopsia singapurensis on the corrosion behavior of mild steel (MS) in 1 mol·L-1 HCl and 1 mol·L-1 H2SO4 was studied using electrochemical techniques, viz., potentiodynamic polarization and AC impedance. The experimental results clearly show that the plant extract effectively inhibits corrosion in both acid media and the inhibition efficiency obtained from the electrochemical techniques is in good agreement. Furthermore, the polarization technique indicates that the extract acts as an anodic type inhibitor in HCl and as a mixed type in H2SO4. Scanning electron microscopy (SEM) was carried out to examine the surface morphological changes of metal specimens in both the inhibited and uninhibited solutions. SEM images show the formation of an adsorbed layer over the metal surface by the inhibitor molecule. The presence of alkaloidal constituents in the plant extract was confirmed by Fourier transform infrared (FTIR) spectroscopy and chemical analysis.     

NONLINEAR WAVE INTERACTIONS IN A MACROSCOPIC PRODUCTION MODEL

In this article,we study the exhaustive analysis of nonlinear wave interactions for a 2×2 homogeneous system of quasilinear hyperbolic partial differential equa...