Laser-based optical emission studies of barium plasma

We present the optical emission characteristics of the barium plasma produced at the surface of barium hydroxide Ba(OH)₂, also known as baryta, generated by the first harmonic (1,064 nm) of a Q-switched Nd:YAG laser. The laser beam was focused on target material by placing it in air at atmospheric pressure. The experimentally observed line profiles of neutral barium have been used to extract the electron temperature using the Boltzmann plot method, whereas the electron number density has been determined from the Stark broadening. The electron temperature is calculated by varying distance from the target surface along the line of propagation of plasma plume and also by varying the laser energy. Besides, we have studied the variation of number density as a function of laser energy as well as its variation with distance from the target surface. It is observed that electron temperature and electron number density increase as laser energy increases.     

Performance comparison among some nonlinear filters for a low cost SINS/GPS integrated solution

The Kalman filter is a familiar minimum mean square estimator for linear systems. In practice, the filter is frequently employed for nonlinear problems. This paper investigates into the application of the Kalman filter’s nonlinear variants, namely the extended Kalman filter (EKF), the unscented Kalman filter (UKF) and the second order central difference filter (CDF2). A low cost strapdown inertial navigation system (SINS) integrated with the global position system (GPS) is the performance evaluation platform for the three nonlinear data synthesis techniques. Here, the discrete-time nonlinear error equations for the SINS are implemented. Test results of a field experiment are presented and performance comparison is made for the aforesaid nonlinear estimation techniques.     

Oscillator strength measurements of the 3p ↦ nd Rydberg transitions of sodium

We report new measurements of the oscillator strengths of the 3p ²P_3/2 ↦nd ²D_{5/2, 3/2} and 3p ²P_1/2 ↦ nd ²D_3/2 Rydberg transitions of sodium using a thermionic diode ion detector in conjunction with the Nd:YAG pumped dye lasers. The ns ²S_1/2 and nd ²D_5/2,3/2 Rydberg series have been recorded via two-step excitation, from the 3p ²P_3/2 and 3p ²P_1/2 intermediate states. Employing the saturation technique, the photoionization cross sections from the 3p ²P_3/2 and 3p ²P_1/2 intermediate states at the first ionization threshold are determined as 7.9(1.3) Mb and 6.7(1.1) Mb respectively. The f-values of the Rydberg transitions are calibrated with the photoionization cross section measured at the first ionization threshold and compared with the earlier data.     

f-pole corrections to the critical parameters of the pomeron

A reggeon field theory with two vacuum quantum numbers Regge poles, the pomeron and the f-reggeon is presented. In such a theory only one stable fixed point appears which is sensibly different from that governing a RFT with the pomeron alone. This fact is responsible for the modifications of the critical parameters of the pomeron. In particular, the intercept of the bare pomeron increases and approaches the phenomenological value.     

Profiling of Antifungal Activities and In Silico Studies of Natural Polyphenols from Some Plants

A worldwide increase in the incidence of fungal infections, emergence of new fungal strains, and antifungal resistance to commercially available antibiotics indicate the need to investigate new treatment options for fungal diseases. Therefore, the interest in exploring the antifungal activity of medicinal plants has now been increased to discover phyto-therapeutics in replacement to conventional antifungal drugs. The study was conducted to explore and identify the mechanism of action of antifungal agents of edible plants, including Cinnamomum zeylanicum, Cinnamomum tamala, Amomum subulatum, Trigonella foenumgraecum, Mentha piperita, Coriandrum sativum, Lactuca sativa, and Brassica oleraceae var. italica. The antifungal potential was assessed via the disc diffusion method and, subsequently, the extracts were assessed for phytochemicals and total antioxidant activity. Potent polyphenols were detected using high-performance liquid chromatography (HPLC) and antifungal mechanism of action was evaluated in silico. Cinnamomum zeylanicum exhibited antifungal activity against all the tested strains while all plant extracts showed antifungal activity against Fusarium solani. Rutin, kaempferol, and quercetin were identified as common polyphenols. In silico studies showed that rutin displayed the greatest affinity with binding pocket of fungal 14-alpha demethylase and nucleoside diphosphokinase with the binding affinity (K_d, −9.4 and −8.9, respectively), as compared to terbinafine. Results indicated that Cinnamomum zeylanicum and Cinnamomum tamala exert their antifungal effect possibly due to kaempferol and rutin, respectively, or possibly by inhibition of nucleoside diphosphokinase (NDK) and 14-alpha demethylase (CYP51), while Amomum subulatum and Trigonella foenum graecum might exhibit antifungal potential due to quercetin. Overall, the study demonstrates that plant-derived products have a high potential to control fungal infections.     

Stress Corrosion Cracking Behavior of Fine-Grained Al5083 Alloys Processed by Equal-Channel Angular Pressing (ECAP)

In the present study, the stress corrosion cracking (SCC) behavior of ECAP Al5083 alloy was investigated in air as well as in 3.5 % NaCl solution using the slow strain rate tensile test (SSRT). The characteristics of grain boundary precipitates (GBPs), specifically the microchemistry of the SCC behavior of Al5083 alloys, both in “as-received” condition and when deformed by the ECAP process, were examined. The correlations between the SCC resistance and GBP microchemistry were examined. A microstructural evaluation was performed using an optical microscope. SCC tests were carried out using a universal tensile testing machine and the fracture surfaces were studied using scanning electron microscopy (SEM). A strain rate of 1×10⁻⁶ s⁻¹ was applied for the SSRT. As the passes increased, the SCC susceptibility of the fine-grained ECAP Al5083 alloy also increased. Moreover, higher ultimate tensile strength and greater elongation were observed. This was due to grain refinement, high-density separations, and the expanded extent of high-density dislocations instigated by severe plastic deformation. Due to the high strength and elongation, the failure analysis showed a ductile mode of fracture. Electron backscattering diffraction (EBSD) analysis was performed to determine more clearly the nature of cracking. EBSD analysis showed that the crack propagation occurred in both transgranular and intergranular modes.     

Extraction-separation of mercury with 1-nephthylthiocarbamide

The extraction of mercury(II) has been studied from mineral acid solution using 1-nephthylthiocarbamide (ANTU) in chloroform-acetone mixture (9:1). The variables such as the concentration of acid and extractant have been optimized. The extractability of some other elements at the optimum conditions for mercury is also studied in order to establish the separation procedure. The probable composition of the extracted species has been deduced from log data. Effect of a number of foreign metal ions and anions has also been studied.     

Isoflavonoid Glycosides from the Rhizomes of Iris germanica

Five new di‐ and triglycosides, irigenin 7‐[O‐β‐D ‐glucopyranosyl‐(1→6)‐β‐D ‐glucopyranoside] ( 1 ), 6‐hydroxygenistein 4′‐[O‐β‐D ‐glucopyranosyl‐(1→6)‐β‐D ‐glucopyranoside] ( 2 ), nigricin 4′‐[O‐β‐D ‐glucopyanosyl‐(1→6)‐β‐D ‐glucopyranoside] ( 3 ), nigricin 4′‐[O‐β‐D ‐glucopyanosyl‐(1→2)‐O‐[α‐L ‐rhamnopyranosyl‐(1→6)]‐β‐D ‐glucopyranoside] ( 4 ), and 7‐{4′‐{[2″‐O‐(4′′′′‐acetyl‐2′′′′‐methoxyphenyl)‐β‐D ‐glucopyranosyl]oxy}‐3′‐(β‐D ‐glucopyranosyloxy)phenyl]‐9‐methoxy‐8H‐1,3‐dioxolo[4,5‐g]‐[1 benzopyran‐8‐one‐] ( 5 ), along with a known compound, nigricin 4′‐(β‐D ‐glucopyranoside) ( 6 ), were isolated from the rhizomes of Iris germanica. The structures of these compounds were established by spectroscopic methods, including 2D NMR spectroscopic techniques.     

Arsenic speciation and other parameters of surface and ground water samples of Jamshoro,Pakistan

This study evaluated and interpreted complex data sets of water samples collected from different sampling origins of ground water (hand pump and tube well) and surface water (municipal, river and canal). The aim was to provide information concerning the apportionment of pollution sources to obtain better information about water quality and possible distribution of As with respect to its speciation. The As (III) formed complex with ammonium pyrrolidinedithiocarbamate (APDC) and extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114, while total iAs in water samples was adsorbed on titanium dioxide (TiO₂) and determined by electrothermal atomic absorption spectrometry. The accuracy of the proposed methodologies was confirmed by standard addition method. The recoveries of As (III) and total inorganic arsenic (iAs) were found to be >98%. The results revealed that the ground water of the area under study was more contaminated as compared to surface water samples. The mean concentration of As (III) and As (V) in the surface water samples was found to be 15.8 and 6.00?µg?L^?1, respectively, whereas, in the case of ground water samples, the contents of As (III) and As (V) ranged from 6.20 to 51.0 and 6.40 to 53.0?µg?L^?1, respectively. Principal component analysis performed on a combined (tube well and hand pump) samples data set extracted two significant factors explaining more than 60% of total variance, which suggested that the contamination sources might be natural or anthropogenic.     

Thick-film technology for ultra high vacuum interfaces of micro-structured traps

We adopt thick-film technology to produce ultra high vacuum compatible interfaces for electrical signals. These interfaces permit voltages of hundreds of volts and currents of several amperes and allow for very compact vacuum setups, useful in quantum optics in general, and in particular for quantum information science using miniaturized traps for ions (Kielpinski et al. in Nature 417:709, 2002) or neutral atoms (Folman et al. in Phys. Rev. Lett. 84:4749, 2000; Treutlein et?al. in Fortschr. Phys. 54:702, 2006; Hofferberth et al. in Nat. Phys. 2:710, 2006). Such printed circuits can also be useful as pure in-vacuum devices. We demonstrate a specific interface which provides 11 current feedthroughs, more than 70?dc feedthroughs and a feedthrough for radio frequencies. We achieve a pressure in the low 10^-11?mbar range and demonstrate the full functionality of the interface by trapping chains of cold ytterbium ions, which requires the presence of all of the above mentioned signals. In order to supply precise time-dependent voltages to the ion trap, a versatile multi-channel device has been developed.