Detection and analysis of paraffin oil adulteration in coconut oil using fiber optic long period grating sensor

A fiber optic sensing system for the detection of adulteration of coconut oil by paraffin oil is experimentally demonstrated. The sensing mechanism is based on the sensitive dependence of the resonance peaks of a long period grating (LPG) on the changes of the refractive index of the environmental medium surrounding the cladding surface of the grating. The wavelength shift of the attenuation bands of the LPG was measured with the sensor immersed in a mixture of paraffin oil and pure coconut oil in different proportions. Detection limit of adulteration was found to be 3% for coconut oil-paraffin oil binary mixture.     

Predominant time scales in fission processes in reactions of S, Ti and Ni with W: zeptosecond versus attosecond

The inhibition of fusion by quasifission is crucial in limiting the formation of superheavy elements in collisions of heavy nuclei. Time scales of ～10(-18) s inferred for fissionlike events from recent crystal blocking measurements were interpreted to show either that quasifission itself is slower than previously believed, or that the fraction of slow fusion-fission is higher than expected. New measurements of mass-angle distributions for (48)Ti and (64)Ni bombarding W targets show that in these reactions quasifission is the dominant process, typically occurring before the system formed after contact has made a single rotation, corresponding to time scales of ≤10(-20) s.     

Synthesis and characterization of LaB6 thin films on tungsten, rhenium, silicon and other substrates and their investigations as?field emitters

The paper deals with the comparative study of nanocrystalline Lanthanum hexaboride (LaB₆) thin films grown on various substrates by Pulsed laser deposition and Arc plasma method. Field emission studies were carried out on LaB₆ films deposited on various substrates show metallic behavior of the emitters. The high value of field enhancement factors, indicating that the electron emission from LaB₆ nanoscale protrusions deposited on emitter surface. The post field emission surface morphology of the emitters showed no significant erosion of the films during continuous operation. The observed behavior indicates that it is linked with the growth of LaB₆ films on substrate crystal structure. The LaB₆ nanocrystallites/nanowires films were synthesized using arc plasma method shows good emission current stability. The LaB₆ micro/nanocrystallites were also obtained by picosecond laser irradiation which gives high enhancement β factor, and good emission current stability along with high current density. The results reveal that nanocrystalline LaB₆ films, exhibit high resistance to ion bombardment and excellent structural stability and are more promising emitters for practical applications in field emission based new generation devices.     

Correlated oscillations in the excitation functions of deep-inelastic collisions: evidence for nuclear pulsars?

Excitation functions for the strongly dissipative collision ¹⁹ F(E _lab = 135–140 MeV)+⁸⁹ Y with an energy step of 250 keV in the lab. system have been measured. The data are consistent with previous measurements and exhibit oscillations, which are interpreted as an indication of quantum chaotic phenomena in dissipative heavy-ion collisions. The Fourier component of the energy autocorrelation of the total projectile-like angle-integrated dissipative yield has been calculated and is found to have a pulsing behaviour with a time interval between sequential pulses equal to the period of the coherent nuclear rotation. This provides another possibility of experimentally detecting quantum chaos in dissipative heavy-ion collisions.     

Monte-Carlo phase diagram of an Ising system with isotropic competing interaction

An Ising model is studied here with isotropic nearest and next nearest neighbour competing interaction along the three axes of a simple cubic system. The phase diagram for this model is determined by Monte-Carlo simulation through a study of the correlation functions.     

Intergranular magnetoresistance in Sr2FeMoO6 from a magnetic tunnel barrier mechanism across grain boundaries

We present magnetization (M) and magnetoresistance (MR) data for a series of Sr2FeMoO6 samples with independent control on antisite defect and grain-boundary densities, which reveal several unexpected features, including a novel switching-like behavior of MR with M. These, in conjunction with model calculations, establish that the MR in Sr2FeMoO6 is dominantly controlled by a new mechanism, derived from the magnetic polarization of grain-boundary regions acting like spin valves, leading to behavior qualitatively different from that usually encountered in tunneling MR. We show that a simple and useful experimental signature for the presence of this spin-valve-type MR (SVMR) is a wider hysteresis in MR compared to that in M.     

Real‐time electro‐diffusion method to discriminate carbon nanomaterials

We report both the experimental and theoretical insights of differential electro‐diffusion behavior of carbon nanomaterials (e.g. single wall, multiwall carbon nanotubes, and graphene). We thus discriminate one from the other in a soft gel system. The differential mobility of such material depends on their intrinsic properties, both extend and rate of migration bearing the discriminatory signature. The mobility analysis is made by a real time monitoring of the respective bands.     

Thermodynamics of water entry in hydrophobic channels of carbon nanotubes

Experiments and computer simulations demonstrate that water spontaneously fills the hydrophobic cavity of a carbon nanotube. To gain a quantitative thermodynamic understanding of this phenomenon, we use the recently developed two phase thermodynamics method to compute translational and rotational entropies of confined water molecules inside single-walled carbon nanotubes and show that the increase in energy of a water molecule inside the nanotube is compensated by the gain in its rotational entropy. The confined water is in equilibrium with the bulk water and the Helmholtz free energy per water molecule of confined water is the same as that in the bulk within the accuracy of the simulation results. A comparison of translational and rotational spectra of water molecules confined in carbon nanotubes with that of bulk water shows significant shifts in the positions of the spectral peaks that are directly related to the tube radius.     

Anomalies in evaporative light scattering detection

A two-dimensional (2-D) “heart-cutting” HPLC system was used to fractionate oligostyrenes into the respective diastereoisomers. For samples of known composition, the response of an ultraviolet (UV) absorbance detector followed the anticipated pattern. The response of an evaporative light-scattering (ELSD) detector on the other hand indicated quite different concentrations for the two diastereoisomers, relative to what was anticipated and what was indicated by the UV detector. Whereas approximately the same concentration was indicated by UV, ELSD in some cases indicated no detection of the later eluting isomer. The magnitude of the errors depended on both the molecular weight and the tacticity of the diastereomers. These anomalies appear to be an artifact of power transform functions imbedded within the firmware processor of the ELSD, invisible to the user.