Anomalous fluoride concentration in groundwater - is it natural or pollution? A stable isotope approach

Fluoride anomalies (up to 11 mg/l) have been detected in groundwater of the central region of Rio Grande do Sul State, Southern Brazil, in an area where fluorosis is endemic. Two hypotheses are investigated concerning the fluoride origin: lithochemical affiliation from regional rock or contamination by fertilisers application. These hypotheses are discussed based on the stable isotope data of water, nitrate, and sulphate, which indicates that the local precipitation is the main groundwater recharge source. The isotopic composition of groundwater sulphate is similar to that of fertiliser sulphate. However, a conclusive assignment of groundwater sulphate to fertiliser origin is not indicated because further possible sulphate sources fall into the same isotopic range. In contrast, the isotopic composition of dissolved nitrate suggests that there is no direct relationship to the use of NPK fertilisers. Hence, an origin of the high fluoride content in groundwater related to long-term rock-water interactions seems likely.     

Optical Solitons in Fiber Bragg Gratings with Polynomial Law Nonlinearity and Cubic–Quartic Dispersive Reflectivity

Optics and Spectroscopy - Optical solitons with fiber Bragg gratings and polynomial law of nonlinear refractive index are addressed in the paper. The auxiliary equation approach together with an...     

Intensity of CO2 bands in the 4.8- to 5.3-μm region. The (1110,0310)II-0000 band

Measurements of the line strengths of the (11¹0,03¹0)_II-00⁰0 band of CO₂ (1932.466 cm^?1) have been made with high resolution. They exhibit a strong Coriolis interaction which enhances the P-branch intensity while reducing that of the R branch. The rotationless dipole moment of the transition and the ξ-constant representing this interaction have been determined as: R(0) = (6.57 ± 0.03) × 10^?4D, ξ = ?0.0598 ± 0.0002.     

Average 2p subshells fluorescence yield values of some elements in the atomic number range 60 ≤ Z ≤ 90

The average 2p (L_2,3) subshells fluorescence yield (?_2,3) in 11 elements with Z ranging from 60 to 90 were measured with corporation of total L_2,3 X-ray production cross-sections. Measurements were carried out exciting L₂ and L₃ subshells of relevant elements that were exposed to beam of selected K X-rays from secondary sources. The measured values were compared with theoretical and semi-empirical values. It is clear that the present values of experimental ?_2,3 are generally smaller than the calculated and semi-empirical values for some elements in the atomic number range 60–90.     

Resonant tunneling properties of inverted Morse double quantum barrier

We study resonant tunneling characteristics of inverted Morse double quantum barrier structures. The effect of electric bias and structure parameters is calculated by using non-equilibrium Green's function method. Results for the transmission coefficients are compared with the structure parameters. Our results show that the widths of the wells and heights of barriers have a significant effect on the transmission properties. We found that the resonant peak of the transmission coefficient decreases with increasing electric field bias. Moreover, resonant energy level increases with increasing barrier height and increasing width parameters.     

Complexiton solutions for two nonlinear partial differential equations via modification of simplified Hirota method

In this study, we obtain complexiton solutions of Sawada–Kotera equation and ninth-order KdV equation. For this cause, we employ Wazwaz and Zhaqilao’s method which can be regarded as generalization of simplified Hirota method through extension real parameters into complex parameters. Special conditions to distinguish complexiton, soliton, and soliton–complexiton interaction solutions from each other are given.     

100 Gb/s RZ-OOK transmission through 212 km deployed SSMF using monolithically integrated ETDM receiver module

100 Gb/s on-off keying (OOK) transmission over 212 km installed standard single-mode fibers using an Indium Phosphide (InP)-based electrical clock-data-recovery (CDR) and demultiplexer module was demonstrated. 5.5 × 10^− 11 bit error rate (BER) performance was achieved and 1.1-dB optical signal-to-noise ratio (OSNR) penalty was required at 10^− 9 BER after transmission.     

Effects of ultrasonic energy on the wash fastness of reactive dyes

The field of ultrasonic is still making strides towards perfection, but already many applications of ultrasonic energy have been found in science and technology. There is also a field called sonochemistry where ultrasonic energy is used to create some chemical and mechanical effects on matter immersed or solved in liquids. It was presumed that ultrasonic textile washing could be a competitive alternative to conventional textile washing techniques; and as such the following experiments were conducted. In this study, the effects of ultrasonic energy on the wash fastness of reactive dyes, which have three different reactive groups, were investigated. After dyeing with the conventional method, the samples were applied with three types of washing processes simultaneously (conventional, ultrasonic probe and ultrasonic bath) and comparisons were made. Three different fixing agents were used in the washing processes. Colourfastness, staining fastness, magnitude of total colour difference (DeltaE) and lightness difference of the colour (DeltaL) values of dyed samples were measured.