A simulation study on photoacoustic signals from red blood cells

A two dimensional simulation study was performed to investigate the photoacoustic signal properties of non-aggregated and aggregated erythrocytes. Spatial distributions of non-aggregated blood samples were generated by employing a Monte Carlo method and aggregated blood samples were simulated using a hexagonal packing scheme. For the non-aggregating case photoacoustic signals demonstrated a monotonic rise with hematocrit. For the aggregating case it was found that spectral (<20 MHz) intensity increased (11 dB at 15.6 MHz) when the aggregate size increased. This study strongly suggests that the assessment of erythrocyte aggregation level in human blood might be possible by using a photoacoustic spectroscopic method.     

A simple technique for evaluation of transmission coefficient at the splice with angular offset and transverse offset for first higher mode propagation in graded index fibers

We present simple and accurate analytical expressions for transmission coefficient at the splice with angular offset and transverse offset in case of first higher mode propagation in graded index fibers. We employ the simple series expression for first higher order modal field for graded index fiber. The evaluation of the concerned parameters based on our formalism requires very little computations. Here, we show that our estimations match excellently well with the exact results in case of step and parabolic index fibers. Further, splice being highly tolerant for longitudinal separation, our analysis is judiciously restricted to the case of transverse and angular mismatches only. The analysis should find application in dual mode graded index fiber in all optical technology.     

Electromagnetic field with induced massive term: Case with scalar field

We consider an interacting system of massless scalar and electromagnetic fields, with the Lagrangian explicitly depending on the electromagnetic potentials, i.e., interaction with broken gauge invariance. The Lagrangian for interaction is chosen in such a way that the electromagnetic field equation acquires an additional term, which in some cases is proportional to the vector potential of the electromagnetic field. This equation can be interpreted as the equation of motion of photon with induced nonzero rest-mass. This system of interacting fields is considered within the scope of Bianchi type-I (BI) cosmological model. It is shown that, as a result of interaction the isotropization process of the expansion takes place.     

Method for vector characterization of polar liquids using frequency-domain spectroscopy

A device for performing vector transmission spectroscopy on aqueous and polar solvent specimens at terahertz frequencies is presented. The device enables the direct measurement of the complex dielectric function across the terahertz band using a Fourier transform IR spectrometer for lossy solutions. Using microfluidic sampling, specimen handling is straightforward and direct measurements on polar specimens are made possible. The method is scalable to longer or shorter wavelengths.     

Titanocene (III) chloride mediated radical induced synthesis of (−)-methylenolactocin and (−)-protolichesterinic acid

Enantioselective synthesis of two anti-tumor antibiotics, (−)-methylenolactocin and (−)-protolichesterinic acid, has been achieved through titanocene(III) chloride mediated radical cyclization reaction starting from commercially available d-mannitol. Titanocene(III) chloride (Cp₂TiCl) was prepared in situ from commercially available titanocene dichloride (Cp₂TiCl₂) and zinc dust in THF.     

Thermohydraulics of turbulent flow through rectangular and square ducts with axial corrugation roughness and twisted-tapes with and without oblique teeth

The heat transfer and the pressure drop characteristics of turbulent flow of air (10,000 < Re < 100,000) through rectangular and square ducts with combined internal axial corrugations on all the surfaces of the ducts and with twisted-tape inserts with and without oblique teeth have been studied experimentally. The axial corrugations in combination with twisted-tapes of all types with oblique teeth have been found to perform better than those without oblique teeth in combination with axial corrugations. The heat transfer and the pressure drop measurements have been taken in separate test sections. Heat transfer tests were carried out in electrically heated stainless steel ducts incorporating uniform wall heat flux boundary conditions. Pressure drop tests were carried out in acrylic ducts. The flow friction and thermal characteristics are governed by duct aspect ratio, corrugation angle, corrugation pitch, twist ratio, space ratio, length, tooth horizontal length and tooth angle of the twisted-tape, Reynolds number and Prandtl number. Correlations developed for friction factor and Nusselt number have predicted the experimental data satisfactorily. The performance of the geometry under investigation has been evaluated. It has been found that on the basis of constant pumping power, up to 55% heat duty increase occurs for the combined axial corrugation and regularly spaced twisted-tape elements inserts with oblique teeth case compared to without oblique teeth twisted-tape inserts cases in the measured experimental parameters space. On the constant heat duty basis, the pumping power has been reduced up to 47% for the combined enhancement geometry than the individual enhancement geometries. However, full-length and short-length twisted-tapes with oblique teeth in combination with axial corrugations show only marginal improvements over the twisted-tapes without oblique teeth.     

Experimental investigation on the flow instability behavior of a multi-channel boiling natural circulation loop at low-pressures

Natural circulation as a mode of heat removal is being considered as a prominent passive feature in the innovative nuclear reactor designs, particularly in boiling-water-reactors, due to its simplicity and economy. However, boiling natural circulation system poses many challenges to designer due to occurrence of various kinds of instabilities such as excursive instability, density wave oscillations, flow pattern transition instability, geysering and metastable states in parallel channels. This problem assumes greater significance particularly at low-pressures i.e. during startup, where there is great difference in the properties of two phases. In light of this, a parallel channel loop has been designed and installed that has a geometrical resemblance to the pressure-tube-type boiling-water-reactor, to investigate into the behavior of boiling natural circulation. The loop comprises of four identical parallel channels connected between two common plenums i.e. steam drum and header. The recirculation path is provided by a single downcomer connected between steam drum and header. Experiments have been conducted over a wide range of power and pressures (1–10 bar). Two distinct unstable zones are observed with respect to power i.e. corresponding to low power (Type-I) and high power (Type-II) with a stable zone at intermediate powers. The nature of oscillations in terms of their amplitude and frequency and their evolution for Type-I and Type-II instabilities are studied with respect to the effect of heater power and pressure. This paper discusses the evolution of unstable and stable behavior along with the nature of flow oscillation in the channels and the effect of pressure on it.     

Palladium(0) nanoparticles-catalyzed ligand-free direct arylation of benzothiazole via C-H bond functionalization

Palladium nanoparticles, generated in situ efficiently catalyzes direct 2-C-H arylation of benzothiazole without requirement of any ligand. A wide range of substituted aryl and heteroaryl iodides participate in this reaction producing a series of 2-aryl/heteroaryl-benzothiazoles in high yields.