Anomalous Raman scattering from phonons and electrons of superconducting FeSe0.82_{0.82}

We report interesting anomalies in the temperature dependent Raman spectra of FeSe$_{0.82}$ measured from 3K to 300K in the spectral range from 60 to 1800 cm$^{-1}$ and determine their origin using complementary first-principles density functional calculations. A phonon mode near 100 cm$^{-1}$ exhibits a sharp increase by $\sim$ 5% in frequency below a temperature T$_s$ ($\sim$ 100 K) attributed to strong spin-phonon coupling and onset of short-range antiferromagnetic order. In addition, two high frequency modes are observed at 1350 cm$^{-1}$ and 1600 cm$^{-1}$, attributed to electronic Raman scattering from ($x^2-y^2$)to $xz$ / $yz$ $d$-orbitals of Fe.Comment: 19 pages, 4 figures, 1 tabl

Structure of the First and Second Neighbor Shells of Water: Quantitative Relation with Translational and Orientational Order

We perform molecular dynamics simulation of water using the TIP5P model to quantify structural order in both the first shell (defined by four nearest neighbors)and second shell (defined by twelve next-nearest neighbors) of a central water molecule. We find the anomalous decrease of orientational order upon compression occurs in both shells, but the anomalous decrease of translational order upon compression occurs {\it mainly in the second shell}. The decreases of translational and orientational orders upon compression ("structural anomaly") are thus correlated only in the second shell. Our findings quantitatively confirm the qualitative idea that the thermodynamic, dynamic and structural anomalies of water are related to changes in the second shell upon compression.Comment: 12 pages, 5 figure

Phonon Anomalies, Orbital-Ordering and Electronic Raman Scattering in iron-pnictide Ca(Fe0.97Co0.03)2As2: Temperature-dependent Raman Study

We report inelastic light scattering studies on Ca(Fe0.97Co0.03)2As2 in a wide spectral range of 120-5200 cm-1 from 5K to 300K, covering the tetragonal to orthorhombic structural transition as well as magnetic transition at Tsm ~ 160K. The mode frequencies of two first-order Raman modes B1g and Eg, both involving displacement of Fe atoms, show sharp increase below Tsm. Concomitantly, the linewidths of all the first-order Raman modes show anomalous broadening below Tsm, attributed to strong spin-phonon coupling. The high frequency modes observed between 400-1200 cm-1 are attributed to the electronic Raman scattering involving the crystal field levels of d-orbitals of Fe2+. The splitting between xz and yz d-orbital levels is shown to be ~ 25 meV which increases as temperature decreases below Tsm. A broad Raman band observed at ~ 3200 cm-1 is assigned to two-magnon excitation of the itinerant Fe 3d antiferromagnet.Comment: Accepted for Publication in JPC

Perception of Operators on Waste Management Systems in Desalination Plants in the United Arab Emirates

The technique of desalinating saltwater is one of the most practical ways to meet the growing need for freshwater in the Gulf countries, especially in the United Arab Emirates (UAE). Desalination offers great benefits in terms of the economy, society, and health; however, there are also negative effects on the environment because of uncontrolled waste disposal. The study aims to determine the perception of operators on waste management systems in desalination plants in the UAE. This study adopted a descriptive research design for collecting data about the impact of unregulated wastewater management and types of unregulated wastes using naturalistic observation and survey. The quantitative data was collected from the respondents using structured and close-ended questionnaires with a 4-point Likert scale. A simple random sampling method was used for selecting respondents in desalination plants. About 150 respondents were included in the study to get their perception of existing control measures and the development of innovative ideas or technology to control the brine impact and contribution of desalination plants to the development of waste management systems in the UAE. Data analysis was done using statistical tools like Chi-square. The results of this study showed that solar power plants benefit the UAE's people and economy. It was also observed that UAE desalination plants kept on trying new techniques like reverse osmosis (RO) and electro dialysis (ED) to reduce the levels of waste production and safeguard the natural surroundings. Hence, UAE desalination plants must adopt proper techniques and waste disposal methods to dispose of harmful brine, which will help preserve and safeguard the environment. It was found that the UAE is taking initiatives to treat and regulate brine discharge from desalination plants in order to provide citizens with safe and clean drinking water. However, the rejected brine and other waste liquids have a negative impact on the marine ecosystem

Common fixed points for two pairs of selfmaps satisfying certain contraction condition in bb-metric spaces

This study introduces generalized contraction for two pairs of selfmaps in complete $b$-metric spaces, and it then establishes the existence of common fixed points under the presumptions that these two pairs of maps are weakly compatible and satisfy the condition for generalized contraction.  A sequence of selfmaps is added as an extension of the same.  Additionally, we demonstrate the same using various hypotheses on two pairs of selfmaps that satisfy the $b$-(E.A)-property.  Some of the conclusions in the literature are extended /generalized to two pairs of self maps by our theorems