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The preparation of two tri-iodide salts, C7H11N2+·I3−·0.5H2O (1) and (C2H5)4N+·I3− (2), synthesized by the slow diffusion method in solution, is reported. Their structures have been characterized by means of single-crystal X-ray diffraction. They consist of two different arrangements of tri-iodide ions, organized in a one-dimensional linear chain for 1 and in two-dimensional T-shaped sheets for 2, stabilized by 4-dimethylaminopyridinium and tetraethylammonium ligands. An asymmetry of the tri-iodide anions is observed in both structures, and is associated to the I⋯I halogen and hydrogen bonding interactions. The generation of the resulting supramolecular networks for these compounds was found to be driven by hydrogen-bond assisted self-assembly. The crystal structures of the two compounds were found to be supported essentially by H⋯I interactions between organic molecules and tri-iodide anions. For compound 2, an additionally stabilization by O⋯H/H⋯O interactions due to the presence of water molecules occurs. The dominant intermolecular interactions and their directionality have been examined by Hirshfeld surfaces and fingerprint analysis. Both compounds were characterized further by FT-IR and Raman spectroscopy, TGA/DTG and UV-visible absorption by means of thin film methods. The target compounds were also studied computationally using density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches to explore their potential performances and to rationalize the experimental results. An electronic transition from 3σg to has been proven to dominate intramolecular charge transfer occurring for both 1 and 2. This electronic communication leads to an HOMO–LUMO energy gap of 4.208 eV for 1 and 4.255 eV for 2. [ABSTRACT FROM AUTHOR]

The title compound, C16H11N2OF, is a member of the azo dye family. The dihedral angle subtended by the benzene ring and the naphthalene ring system measures 18.75 (7)°, indicating that the compound is not perfectly planar. An intramolecular N--H...O hydrogen bond occurs between the imino and carbonyl groups. In the crystal, the molecules are linked into inversion dimers by C--H...O interactions. Aromatic π-π stacking between the naphthalene ring systems lead to the formation of chains along [001]. A Hirshfeld surface analysis was undertaken to investigate and quantify the intermolecular interactions. In addition, energy frameworks were used to examine the cooperative effect of these intermolecular interactions across the crystal, showing dispersion energy to be the most influential factor in the crystal organization of the compound. [ABSTRACT FROM AUTHOR]

This case study focuses on the area of El Plateado near the city of Loja, Ecuador, where landslides with a high impact on infrastructures require monitoring and control. The main objectives of this work are the characterization of the landslide and the monitoring of its kinematics. Four flights were conducted using a remotely piloted aerial vehicle (RPAS) to capture aerial images that were processed with SfM techniques to generate digital elevation models (DEMs) and orthoimages of high resolution (0.05 m) and sufficient accuracy (below 0.05 m) for subsequent analyses. Thus, the DEM of differences (DoD) and profiles are obtained, but a morphometric analysis is conducted to quantitatively characterize the landslide's elements and study its evolution. Parameters such as slope, aspect, topographic position index (TPI), terrain roughness index (TRI), and topographic wetness index (TWI) are analyzed. The results show a higher slope and roughness for scarps compared to stable areas and other elements. From TPI, slope break lines have been extracted, which allow the identification of landslide features such as scarps and toe tip. The landslide shows important changes in the landslide body surface, the retraction of the main scarp, and advances of the foot. A general decrease in average slope and TRI and an increase in TWI are also observed due to the landslide evolution and stabilization. The presence of fissures and the infiltration of rainfall water in the unsaturated soil layers, which consist of high-plasticity clays and silts, contribute to the instability. Thus, the study provides insights into the measurement accuracy, identification and characterization of landslide elements, morphometric analysis, landslide evolution, and the relationship with geotechnical factors that contribute to a better understanding of landslides. A higher frequency of the RPAS surveys and quality of geotechnical and meteorological data are required to improve the instability analysis together with a major automation of the GIS procedures. [ABSTRACT FROM AUTHOR]

Fluorine is a very common element in the Earth's crust and is present in the air, food, and in natural waters. It never meets in the free state in nature due to its high reactivity, and it comes in the form of fluorides. Depending on the concentration of fluorine absorbed, it may be beneficial or harmful to human health. Similar to any trace element, fluoride ion is beneficial for the human body at low levels, but as soon as its concentration becomes too high, it is toxic, inducing dental and bone fluorosis. The lowering of fluoride concentrations that exceed the recommended standards in drinking water is practiced in various ways around the world. The adsorption process has been classified as one of the most efficient methods for the removal of fluoride from water as it is environmentally friendly, easy to operate, and cost-effective. The present study deals with fluoride ion adsorption on modified zeolite. There are several influential parameters, such as zeolite particle size, stirring rate, solution pH, initial concentration of fluoride, contact time, and solution temperature. The maximum removal efficiency of the modified zeolite adsorbent was 94% at 5 mg/L fluoride initial concentration, pH 6.3, and 0.5 g modified zeolite mass. The adsorption rate increases accordingly with increases in the stirring rate and pH value and decreases when the initial fluoride concentration is increased. The evaluation was enhanced by the study of adsorption isotherms using the Langmuir and Freundlich models. The Langmuir isotherm corresponds with the experimental results of the fluoride ions adsorption with a correlation value of 0.994. The kinetic analysis results of the fluoride ions adsorption on modified zeolite allowed us to demonstrate that the process primarily follows a pseudo-second-order and then, in the next step, follows a pseudo-first-order model. Thermodynamic parameters were calculated, and the ΔG° value is found to be in the range of −0.266 kJ/mol up to 1.613 kJ/mol amidst an increase in temperature from 298.2 to 331.7 K. The negative values of the free enthalpy ΔG° mean that the adsorption of fluoride ions on the modified zeolite is spontaneous, and the positive value of the enthalpy ∆H° shows that the adsorption process is endothermic. The ∆S° values of entropy indicate the fluoride adsorption randomness characteristics at the zeolite-solution interface. [ABSTRACT FROM AUTHOR]

• The molecular structure of FPDN was determined using X-ray diffraction. • Crystal voids were visualized to understand the crystal packing. • Spectral studies were conducted using IR spectroscopy. • The DFT calculations of the compound were examined. • The DFT theoretical results were compared with the experimental data. • Inhibitory activities for the 11-beta enzyme were shown by the FPDN compound. • Molecular docking analysis was performed in relation to the inhibitory activities of the 11-beta enzyme of FPDN. • The compound is suggested to be a promising drug candidate according to biological evaluation and ADMET predictions. 1-[(E)-2-(2-fluorophenyl) diazan-1-ylidene] naphthalen-2(1H)-one (FPDN) is an organic compound that belongs to the azo dye family. The structure of the compound was determined using single-crystal X-ray diffraction (XRD). The crystal voids were examined to understand the crystal packing. The antioxidant activity of the molecule was evaluated by DPPH (2, 2-diphenyl-1-picrylhydrazyl) and ABTS [2, 2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)] assays. The effective concentration (IC 50) indicated that the compound has good antioxidant activity. Additionally, the compound was characterized using Fourier-transform infrared (FT-IR) spectroscopy. Using Density Functional Theory (DFT) calculations, theoretical studies are compared with the experimental results. These studies were found to be in good agreement with the experimental data. The swissTargetPrediction online tool was used to estimate the most probable macromolecular targets of FPDN. The predicted target, 11-beta-hydroxysteroid dehydrogenase 1 (11β-HSD1), was then used for molecular docking studies to examine the potential inhibition of FPDN against this enzyme. Furthermore, the pharmacokinetic and physicochemical features of the FPDN molecule were explored using the SwissADME online tool. [Display omitted] [ABSTRACT FROM AUTHOR]

The main result of this paper is to compute the a (1) -relative 1 - cohomology space of the Lie algebra Vect (R) , with coefficients in the space of binary bidifferential operators that act on λ - densities, D λ , ν , μ , vanishing on the 2-dimensional affine Lie algebra a (1) . [ABSTRACT FROM AUTHOR]

Inflammatory myofibroblastic tumor (IMT) is a rare neoplasm of children and young adults. It consists of myofibroblastic cells of borderline malignancy admixed with inflammatory cells. According to the WHO classification, of tumors, it is a soft-tissue tumor with an intermediate malignant potential. It may arise within numerous organs. Ureteral location is exceedingly rare. We report the exceptional case of a 4-year-old boy presenting with a giant right ureteral IMT removed during a nephroureterectomy. Histology and immunohistochemistry confirmed the diagnosis of an IMT with Anaplastic Lymphoma Kinase 1 expression. A 7 months follow-up showed no recurrence or distant metastasis. We also reviewed the literature for similar cases of pediatric ureteral IMT. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the oral manifestations and salivary composition in type 2 diabetics with periodontitis and to evaluate their association with CA6 gene polymorphism rs2274327. Oral examination was performed by a single periodontist for 300 type 2 diabetics. Whole unstimulated saliva and blood were collected. The salivary pH, buffer capacity and flow rate were later measured. Immunoglobulin A and electrolytes were assessed using an autoanalyzer. CA6 gene polymorphism rs2274327 was screened by PCR-RFLP assay. The statistical analysis was performed using the SPSS 20.0 version. The salivary pH, buffer capacity and flow rate were significantly lower in the patients carrying TT genotype compared to CC and CT genotype carriers (p <.05). Furthermore, the DMFT index, OHI-s, PI, PPD and CAL were significantly higher in the subjects with TT genotype (p <.05). Carrying at least one T allele seemed to increase the risk of dental caries (OR = 2.59, p <.001), xerostomia (OR = 2.11, p=.003) and taste impairment (OR = 1.97, p <.05). CA6 gene polymorphism rs2274327 seemed to increase the risk of developing, dental caries, periodontitis, xerostomia and taste impairment in type 2 diabetics. [ABSTRACT FROM AUTHOR]

The importance of the use of various drugs as corrosion inhibitors has developed. In this context, the corrosion inhibition of C38 steel in 1.0 M H3PO4 medium by omeprazole has been evaluated by weight loss tests, potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The surface morphology has been characterized by scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy. The Tafel polarization analysis shows that omeprazole is a mixed-type inhibitor. The results obtained by electrochemical impedance spectroscopy indicate that the inhibition efficacy increases with inhibitor concentration. The results obtained from the standard free energy of adsorption of (Δ G ads 0 = - 37.86 kJ mol−1) are consistent with a physisorption and chemisorption process. The scanning electron microscopy allowed the visualization of a protective layer on the C38 steel surface after the addition of the inhibitor. The results obtained from different tested techniques showed excellent inhibition efficiency up to 99% using omeprazole for C38 steel in a phosphoric acid medium. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the possibility of using computer algebra tools in the process of modeling and qualitative analysis of mechanical systems and problems from theoretical physics. We describe some constructions—Courant algebroids and Dirac structures—from the so-called generalized geometry. They prove to be a convenient language for studying the internal structure of the differential equations of port-Hamiltonian and implicit Lagrangian systems, which describe dissipative or coupled mechanical systems and systems with constraints, respectively. For both classes of systems, we formulate some open problems that can be solved using computer algebra tools and methods. We also recall the definitions of graded manifolds and Q‑structures from graded geometry. On particular examples, we explain how classical differential geometry is described in the framework of the graded formalism and what related computational questions can arise. This direction of research is apparently an almost unexplored branch of computer algebra. [ABSTRACT FROM AUTHOR]

In this study a validated antenna into simulation and through measurement has been described and analyzed. The coplanar waveguide (CPW) technique has been chosen to feed the radiating patch while the two ground planes have been partially designed in the top side of the substrate. The fractal geometry, applied to the circular radiator, has been obtained by merging the circular and rectangular shapes. The fiberglass FR-4, with a single side of 35µm copper thickness, has been used to achieve the antenna material with a permittivity of 4.4, a thickness of 1.6mm, a loss tangent of 0.025 and an overall dimension of 34x43 mm². The proposed CPW fractal antenna has been configured to operate in the frequency range 3.1-10.6 GHz published by the federal communications commission (FCC) as an ultra-wide band (UWB). To calculate the return loss, the gain, the current density and the radiation pattern of the simulated antenna, two electromagnetic solvers have been involved which are the CST microwave studio and ADS. The series of measurement have been performed by using the network analyzer and the anechoic chamber in order to confirm the computed antenna. [ABSTRACT FROM AUTHOR]

This paper presents a review of the data acquisition procedures of geotechnical parameters for rock slope stability assessment and the proposal of some new improvements. For this purpose, a piece of research based on the slope mass rating classification system using close-range terrestrial digital photogrammetry (CR-TDP) has led to improvements in quality and timing of discontinuity data acquisition, and analyzes the suitability of each one of the parameters when applied to weak foliated rocks. TDP allows rapid 3D image acquisition of a rock slope, which can be analyzed using software to determine the geometrical parameters that affect stability. A fast procedure to perform the photogrammetric, non-contact survey in order to obtain the 3D images is shown in this paper. Being a rapid and single-person task, this procedure provides enough precision to be applied to weak foliated rock slopes with non-well-defined geometry. Furthermore, the study has focused on highly foliated rock outcrops, in which high resolution in the 3D images is very desirable. This research was applied to mountain road cuts, in which the use of TDP with a very close range was necessary. Through an application on weak rocks in the Alpujarras (Andalusia, Spain), this work analyzes the bias when applying TDP to materials such as these, under progressive weathering processes. [ABSTRACT FROM AUTHOR]

The purpose of this study is to advance the development and characterisation of a novel electrochemical sensor for methylene blue detection in aqueous medium. The composite of Argan oil cake waste containing nanoparticles of zinc oxide was employed as an environment friendly modification of carbon paste electrode (AOCW/ZnOnps-CPE) for methylene blue detection. The electrochemical investigation by cyclic voltammetry (CV), square wave voltammetry (SWV) reveals an enhancement in the detection current intensity after the electrode modification. After calibration curve, the obtained detection limit of methylene blue is 0,06 nM, under the following optimal conditions: acetate buffer as supporting electrolyte, pH = 4, −1 V and 110s as accumulation potential and time, respectively. In this study, the modified electrode has been proven to be a promising alternative for the development of a sensitive sensor to control wastewater containing MB sensitivity, and repeatability. This sensor was used to identify MB in irrigation water, and it shows a good performance. [ABSTRACT FROM AUTHOR]

In this work, a formal deduction of a two-dimensional membrane theory, similar to Landau-Lifshitz model, is performed via an asymptotic development of the weak formulation of the three-dimensional equations of elasticity. Some interesting aspects of the deduced model are investigated, in particular the property of obtaining a hyperbolic equation for the out-of-plane displacement under a certain class of boundary conditions and loads. Some simple cases are analyzed to show the relevant aspects of the model and the phenomenology that can be addressed. In particular, it is shown how this mathematical formulation is capable to describe instabilities well known as wrinkling, often observed for the buckling of very thin membranes. [ABSTRACT FROM AUTHOR]

A Microstrip Antenna (MSA) has been computed and analysed in this study by using CST of Microwave studio as Electromagnetic solver by generating the coefficient of reflection, the Gain, the density of current and the radiation pattern in the frequency range 3.1-10.6 GHz which commercialised by the Federal communication commission (FCC) as an Ultra-wide band (UWB) frequency range. The substrate used to achieve the proposed structure is the FR4-Epoxy with a thickness of 1.6 mm, a constant dielectric of 4.4 and a loss tangent of 0.025. The radiating patch is a circular shape etched with different sizes to create the fractal geometry. The transmission line has been designed by including a tapered section in the part connected to the radiator. The design of the antenna has been verified by using ADS and CST solvers. The fabrication of the antenna has been performed in order to measure the coefficient of reflection and the radiation pattern. [ABSTRACT FROM AUTHOR]

Summary: Adipose tissue is an important endocrine organ that secretes a number of adipokines, like Leptin (LEP). The aim this study was to investigate the prevalence of single nucleotide polymorphisms in LEP gene (LEP 3′UTR A/C, −2548 G/A) and LEPR (K109R and Q223R) and their association with Leptin level and obesity. We recruited 169 non‐obese (body mass index [BMI] = 24.51‐3.69 kg/m2) and 160 obese (BMI = 36‐4.78 kg/m2) patients. Genotyping was performed using polymerase chain reaction‐restriction fragment length polymorphism, BMI was calculated, and Leptin level was measured by ELISA. Statistical analyses were performed by spss19.0. According to LEP 3′UTR A/C polymorphism, AC and CC genotype carriers had higher Leptin levels than AA genotype carriers, respectively, 31[0.05‐148.8] (P = .008) vs 41[0.05‐111.6] (P = .003). The K109R polymorphism was associated with obesity (P = .025) and seems to significantly decrease the LEP levels (P < .001). Concerning LEP G2548A polymorphism, our results showed that the OR of obesity associated with 2548 AA/GG was 1.87[1.106‐2.78] P = .028 vs 1.41[1.035‐1.85] P = .045 for 223AA/GG polymorphism. In our haplotype analysis, one haplotype seems to be the more protective and one other seems to be the highest risk to obesity. LEP 3′UTR A/C and LEPR K109R polymorphisms were associated with Leptin level and obesity. [ABSTRACT FROM AUTHOR]

Purpose:Dementia is a multifactorial idiopathic pathology caused by clinical, eDementia is a multifactorial idiopathic pathology caused by clinical, environmental and genetic factors. Hence, its etiology is still unknown. We aimed to evaluate the association between five genetic risk factors for vascular diseases and dementia individually and when gathered in haplotypes.Materials and Method:We enrolled 200 dementia patients and 300 controls. All subjects were genotyped for vascular diseaseassociated polymorphisms in the genes coding for Apolipoprotein-E (ApoE), angiotensin converting enzyme (ACE) and Paraoxonase-1 (PON1).Results:The association between dementia risk and all the studied polymorphisms except of PON1-Q192R was found to be significant. Carrying the ApoE e4 allele seems to increase dementia risk by 4.32 fold (p= 0.001). The risk associated with ACE I and PON1-L55M T alleles were lower (2.58 and 2.11 fold,p< 0.001 andp= 0.015, respectively). When combined in haplotypes, these polymorphisms showed a cumulative and synergetic effect. GTICC haplotype appears to be associated with 9-fold dementia risk (p< 0.001), whereas AADTT seems to reduce dementia risk by 80% (p= 0.003). Conclusion: Our results suggest that, ApoE ε4, ACE I and PON1-L55M T alleles are associated with dementia risk whether these polymorphisms were studied separately or gathered in haplotypes. Still, the contribution of each gene to the pathophysiological development of dementia must be more investigated. [ABSTRACT FROM AUTHOR]

Landslide hazard in a region limited to data from a regional scale about triggering factors is assessed via cross tabulation between determining factors and landslides with recent activity. Firstly, landslide susceptibility was evaluated and validated through a bivariate statistical method between the previously identified stability conditioning factors and the mapped landslides. In this way, the most susceptible areas for assessing landslide hazards were selected. The main problem to solve in this type of research is the landslide activity. For this purpose, several techniques were applied: news reports, differential interferometric synthetic aperture radar, digital photogrammetry, light detection and ranging, photointerpretation, and dendrochronology. Both the strong and weak points of these techniques are also mentioned. The landslide return period was computed via the association between landslide activity and triggering factors, in this case annual rainfall. Finally, landslide hazard was mapped solely based on landslides with recent activity and their computed return period. The relationship between landslide occurrence and triggering factors shows that, according to both the considered assumptions and the observations made, deep-seated landslides are triggered or reactivated together with superficial landslides once every 18 years, while superficial landslides as flows or falls occur once every 5 years. The results show that there is generally a low landslide hazard in the study zone, especially when compared to landslide susceptibility. This means that landslides are mainly dormant from a natural evolution point of view, but could be reactivated as a result of geomorphological, climate, or human changes. In any case, the landslide hazard is successfully assessed, with a prediction of a 6% annual probability of a high hazard in 5% of the area, intersecting with the main infrastructures of the region; thus, control strategies are justified in order to avoid damage in extraordinary rainfall periods. [ABSTRACT FROM AUTHOR]

We show that the probability distribution corresponding to a fully random tracial state of a system of spin-S particles satisfies a diffusion-like equation. The diffusion coefficient turns out to be equal to S ( S + 1 ) / 6 , where S is the magnitude of the spin of each particle. We also present a bosonization scheme for the lowering and raising total spin operators. [ABSTRACT FROM AUTHOR]

A series of protonated polyamine derivatives have been considered as H-bond donor units for the construction of extended networks by assemblage with the anionic metal-oxalate complex [Zr(C2O4)4]4− by means of charge-assisted H-bonds. In order to evaluate the parameters that favor the formation of 3D open-framework architectures, linear, flexible and V-shaped organic cations (Hn-Lx)y+ have been selected. Four different compounds of the formula [(H2-L1)2{Zr(C2O4)4}]·2H2O, 1, [(H2-L2)2{Zr(C2O4)4}]·4H2O, 2, [(H2-L3)2{Zr(C2O4)4}]·4H2O, 3, and [(H-L4)4{Zr(C2O4)4}]·2H2O, 4 (with L1 = thiocarbohydrazide, L2 = ortho-phenylene diamine, L3 = piperazine and L4 = 4-aminopyridine) are reported. Depending on the cations' shape, 2D to 3D H-bonded networks have been characterized. The crystal structures of all four architectures as well as their thermal stabilities are reported. The dominant intermolecular interactions and their directionality have been examined by Hirshfeld surfaces and fingerprint analysis. [ABSTRACT FROM AUTHOR]

• [Qx-H+]BiI 4 (1) contains polymeric cis -[BiI 4 −] n iodobismuthate anions. • The layered structure of compound 2 is constructed yielding a graphite-like supramolecular architecture. • For the two compounds, the identification of the 3D networks generated by supramolecular interactions was assessed by Hirshfeld analyses. • The optical properties of 2 allowed to determine the HOMO-LUMO gap. • Thermal and energetic properties of 2 have been revealed a potential as high energy density material (HEDM). Treatment of an acetone solution of Bi(NO 3) 3 with quinoxaline (Qx) in the presence of hydroiodic acid produces in moderate yield the crystallographically characterized 1D-polymeric salt-like iodobismutate [(Qx- H +)BiI 4 ] n (1), whose negative charge is balanced by mono-protonated quinoxalinium counterions. The main product is an unusual tetra(nitrated) quinoxaline derivative, namely 5,6,7,8-tetranitro-1,2,3,4-tetrahydroquinoxaline-2,3-diol (2), which was formed accidently under mild reaction conditions. The molecular structure of this organic compound 2 was determined by single-crystal X-ray diffraction and its strong intermolecular interactions giving rise to a supramolecular three-dimensional network were assessed by IR spectroscopy and a Hirshfeld surface analysis. Structural analysis reveals that the crystal structure is supported essentially by O‒H ··· O and N‒H ··· O intermolecular hydrogen bonds and additionally stabilized by N‒O ··· π interactions. The ground-state molecular structure of this novel organic heterocycle has been optimized by DFT calculation. The optical band gap, caused by intramolecular charge transfer (ICT) from the 1,2,3,4-tetrahydroquinoxaline-2,3-diol fragment to the nitro groups, has been estimated to be 2.04 eV. High density, positive heat of formation and very good thermal stability according to thermal analysis by TGA, DTA and DSC characterize tetranitro compound 2 as energetic material. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper the design of a novel unidirectional light transmission device is reported. The device consists of a waveguide coupled into three microrings. It is shown that the radii and the air gaps between the microrings are key parameters in achieving unidirectional propagation of the light. The incident light impinging from left and right directions has different transmission spectra. The results obtained by coupled mod theory are in good agreement with those achieved by using FDTD method. [ABSTRACT FROM AUTHOR]

Monte-Carlo simulation is used to study the surface recombination effects on the electron beam induced current technique. The current is collected by a nanoscale electrode. We choose three values for the surface recombination velocity reflecting the sample surface states; zero, infinite value and an intermediate one. From a probabilistic point of view, each of the three surface velocities is described by a collection probability related to the surface effects and to the electrode size. Even if probabilities corresponding to zero and intermediate velocity are chosen to be close one to the other, the results are different. For intermediate velocity the collection efficiency profile is similar to that corresponding to the infinite velocity. Both profiles narrow with diminution of their maximum. At electron beam energies higher than 4 keV the profiles are superimposed because of the large penetration depth, and the smallness of the electrode and its depletion zone. [ABSTRACT FROM AUTHOR]

Fresh groundwater is sometimes enriched with dissolved ferrous iron (Fe(II)) that restricts its consumption as potable water because it forms colloidal red matter (mainly ferric oxyhydroxides) under oxic conditions at near neutral pH (>6) conditions. As already demonstrated, natural or synthetic calcite material can be used to accelerate the iron oxidation process from Fe(II) to Fe(III), a process that then enhances its precipitation at the calcite-solution interface as confirmed by in situ atomic force microcopy (AFM) observations in this study. The present study mainly reports on a simplified water treatment method to remove ferrous iron (Fe(II)) from water via aqueous carbonation of calcium hydroxide (Ca(OH) 2 ) at ambient temperature (≈20 °C) and moderate CO 2 pressure (10 bar) conditions. In practice, high concentrations of dissolved iron (up to 100 mg/L) can be successfully removed using only 4 g of Ca(OH) 2 per liter of Fe-rich solution (close to 100% of efficiency) and a short treatment time is required (<1 h). This method offers various advantages compared with other calcite-based water treatments. For example, other pre-existent dissolved toxic and eutrophic ions such as As, Cu, Cd, Se, P, S, N, etc. can be simultaneously removed from water during the precipitation of calcite and iron oxyhydroxide nanoparticles (<100 nm). Additionally, the dissolution of calcium hydroxide prior to the carbonation process increases the pH (12.4), a process that can act as a softening agent in the water being treated. Finally, the resultant red solid-residue containing mainly calcite and iron oxyhydroxide (FeOOH type) nanoparticles could be reused as pigment or mineral filler powder for industrial applications. This integrated method could be used successfully to remove toxic dissolved ions from water while generating solid residues with industrial uses. [ABSTRACT FROM AUTHOR]

Within the scope of a systematic study of eight-coordinate Zr IV chelates, a mixed potassium trioxalatozirconate (IV) complex, namely K 2 [Zr(C 2 O 4 ) 2 (μ-C 2 O 4 )] · 2H 2 O, has been synthesized. Its structure framework represents a zirconium (IV) carboxylate polymer displaying interesting polymeric zigzag chains of ZrO 8 units running parallel to the c axis. Stereo-chemical study of polyhedral eight-vertex structure revealed that in ZrO 8 the average in the coordination polyhedral is a Biaugmented trigonal prism J50 chelate. Hirshfeld surface and fingerprint plot analysis revealed that O · · · O intermolecular interactions are the most important ones accountable for the reinforcement of the supramolecular assembly of the coordination polymers. The thermal decomposition has been studied by coupled ATD-TGA and supplemented by infrared and Raman emission spectroscopy as a function of temperature which nicely corroborated the crystal structure and suggest a deformation in the Zr–O chelate with departure of water molecules. [ABSTRACT FROM AUTHOR]

• Time integrator. • Stiff equations. • Stability. • Borel summation. • Divergent series. A stability analysis of the Borel–Padé–Laplace series summation technique, used as explicit time integrator, is carried out. Its numerical performance on stiff and non-stiff problems is analyzed. Applications to ordinary and partial differential equations are presented. The results are compared with those of many popular schemes designed for stiff and non-stiff equations. [ABSTRACT FROM AUTHOR]

From mathematical and numerical points of view, we study the sensitivity with respect to parametric evolutions, of the error obtained by approximating a given parametric partial differential equation using a proper orthogonal decomposition (POD) basis determined once and for all, with association to a fixed parameter. More precisely, we will be considering the one-dimensional Burgers equation with a source term. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we present contributions concerning a mathematical study of the sensitivity of a reduced order model (ROM) by the proper orthogonal decomposition (POD) technique applied to a quasi-linear parabolic equation. In particular, we apply our theoretical study to the Navier–Stokes equations for a 2D incompressible fluid flow. We present a numerical test of our theoretical result, for an unsteady fluid flow in a channel around a circular cylinder. [Copyright &y& Elsevier]

The problem of the quantum description of the damping of a 1D chain of coupled oscillators with periodic boundary conditions in the Markovian regime is solved. The equations of motion of the normal modes are derived, and the evolution in time of their mean values and variances is explicitly studied. Furthermore, we investigate the effect of the diffusion and the friction on the dynamics of the chain. It is shown that when the off-diagonal elements of the diffusion and friction tensors are taken into account, the most notable contribution of these processes is observed in the mode in which all the oscillators undergo an in-phase vibration. [ABSTRACT FROM AUTHOR]

Abstract: Borel’s technique of divergent series resummation is transformed into a numerical code and used as a time integration scheme. It is applied to the resolution of regular and singular problems arising in fluid mechanics. Its efficiency is compared to those of classical discretization schemes. [Copyright &y& Elsevier]

We report on a nontrivial bosonization scheme for spin operators. It is shown that in the large N limit, at an infinite temperature, the operators ΣNk=1NŜk±/vN behave like the creation and annihilation operators, i.e. a† and a, corresponding to a harmonic oscillator in thermal equilibrium, whose temperature and frequency are related by ħω/(kBT) = ln 3. The z-component is found to be equivalent to the position variable of another harmonic oscillator occupying its ground Gaussian state at zero temperature. The obtained results are applied to the Heisenberg XY Hamiltonian at a finite temperature. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for the stability analysis of cuts in rock slopes. A kinematic analysis of the different types of failure (planar, wedge, and toppling) is developed using GIS, following which a probabilistic analysis is made of the limit equilibrium in slopes where the conditions for kinematic failure are satisfied. The results were verified by comparing the evaluation against the observed stability conditions in 40 road cuts along 4 km of national road N-340, on the Mediterranean edge of Granada province (southern Spain). The validation analysis showed that for some 90% of the slopes studied there was a reasonable fit between the observed and evaluated stability, indicating the proposed methodology is suitable for the preliminary analysis of the stability conditions on rock slopes. [ABSTRACT FROM AUTHOR]

In the present study we report the synthesis, crystal structure, spectroscopic and thermal analysis of mixed alkali A(NH)(HCO)(HCO)(HO) with A = K, Rb. Single crystal refinements showed that the two compounds Rb(NH)(HCO)(HCO)(HO) and K(NH)(HCO)(HCO)(HO) adopt P − 1 space group. The nine fold coordination cationic sites are randomly occupied by Rb/NH and K/NH respectively for rubidium and potassium compounds. The structure consists of a three-dimensional network formed by the succession along (c) axis of corrugated sheets formed by alkali polyhedra layers in the packing of four-membered rings [A(HCO)(HCO)] linked and bridged by oxalate groups that behave as bi and tetradentate ligand under three different coordination modes. The stability of the crystal lattice is ensured by interesting hydrogen bonding contacts: N-H···O and O-H···O. The thermal behavior under air reveals two anomalies at 368 and 402 K attributed respectively to a structural phase transition probably due to the reorientation of ammonium tetrahedral and to the release of crystalline water. IR spectroscopy further confirms that this material loses crystallization water gradually in the temperature range 400-460 K. Graphical Abstract: Crystal structures of Rb(NH)(HCO)(HCO)(HO) and K(NH)(HCO)(HCO)(HO) adopt isotypic three dimensional frameworks formed by the succession along (c) axis of corrugated sheets. Structure of A(NH)(HCO)(HCO)(HO).[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this paper, an implicit coupling algorithm for fluid-structure interaction problems with under-time steps for the solid is presented. Its implementation on two configurations is achieved by using the CASTEM finite-elements code. First, the free oscillations of a cylinder in an annular fluid domain where its movement is determined by the coupled fluid-solid action is considered in the case of viscous fluid. It should be noted that the implicit coupling algorithm gives the best prediction of the structure oscillations. The under-time steps for the solid are introduced in order to obtain better results. Then, an application whose final objective is to model a floating barrage is studied. The main goal of this application is to predict the displacements of a ring completely immersed and anchored by a cable to the lower boundary of the fluid domain. The finite-element discretization of the Navier-Stokes equations in the ALE formulation is used [ABSTRACT FROM AUTHOR]

Abstract: The two-dimensional Burgers’ equations are solved here using the A Priori Reduction method. This method is based on an iterative procedure which consists in building a basis for the solution where at each iteration the basis is improved. The method is called a priori because it does not need any prior knowledge of the solution, which is not the case if the standard Karhunen–Loéve decomposition is used. The accuracy of the APR method is compared with the standard Newton–Raphson scheme and with results from the literature. The APR basis is also compared with the Karhunen–Loéve basis. [Copyright &y& Elsevier]

linear one-dimensional model for thin-walled rods with open strongly curved cross-section, obtained by asymptotic methods is presented. A dimensional analysis of the linear three-dimensional equilibrium equations yields dimensionless numbers that reflect the geometry of the structure and the level of applied forces. For a given force level, the order of magnitude of the displacements and the corresponding one-dimensional model are deduced by asymptotic expansions. In the case of low force levels, we obtain a one-dimensional model whose kinematics, traction, and twist equations correspond to the Vlassov ones. However, this model couples twist and bending effects in the bending equations, unlike the Vlassov model where the twist angle and the bending displacement are uncoupled [ABSTRACT FROM AUTHOR]

Invariant numerical schemes possess properties that may overcome the numerical properties of most of classical schemes. When they are constructed with moving frames, invariant schemes can present more stability and accuracy. The cornerstone is to select relevant moving frames. We present a new algorithmic process to do this. The construction of invariant schemes consists in parametrizing the scheme with constant coefficients. These coefficients are determined in order to satisfy a fixed order of accuracy and an equivariance condition. Numerical applications with the Burgers equation illustrate the high performances of the process. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the non-isothermal NavierߞStokes equations are studied from the group theory point of view. The symmetry group of the equations is presented and discussed. Some standard turbulence models are analyzed with the symmetries of the equations. A class of turbulence models which preserve the physical properties contained in the symmetry group is built. The proposed turbulence models are applied to an illustrative example of natural convection in a differentially heated cavity, and the results are presented. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents reduced order modelling (ROM) in fluid–structure interaction (FSI). The ROM via the proper orthogonal decomposition (POD) method has been chosen, due to its efficiency in the domain of fluid mechanics. POD-ROM is based on a low-order dynamical system obtained by projecting the nonlinear Navier–Stokes equations on a smaller number of POD modes. These POD modes are spatial and temporally independent. In FSI, the fluid and structure domains are moving, owing to which the POD method cannot be applied directly to reduce the equations of each domain. This article proposes to compute the POD modes for a global velocity field (fluid and solid), and then to construct a low-order dynamical system. The structure domain can be decomposed as a rigid domain, with a finite number of degrees of freedom. This low-order dynamical system is obtained by using a multiphase method similar to the fictitious domain method. This multiphase method extends the Navier–Stokes equations to the solid domain by using a penalisation method and a Lagrangian multiplier. By projecting these equations on the POD modes obtained for the global velocity field, a nonlinear low-order dynamical system is obtained and tested on a case of high Reynolds number. [Copyright &y& Elsevier]

Abstract: We propose a new approach for moving frame construction that allows to make finite difference scheme invariant. This approach takes into account the order of accuracy and guarantees numerical properties of invariant schemes that overcome those of classical schemes. Benefits obtained with this process are illustrated with the Burgers equation. [Copyright &y& Elsevier]

Abstract: We derive analytical properties for the degeneracy occurring in the decomposition of the state space . We also investigate the dynamics of two qubits coupled via Ising interactions to separate spin baths, and we study the thermodynamic limit. [Copyright &y& Elsevier]

The present paper is Part 2 of a two parts paper on flow around vibrating wind turbine airfoils. The first part of the paper dealt with a forced oscillating airfoil. Part 2 focuses on free vibrating airfoils. The flow induced vibrations on two airfoils used for wind turbine blades are investigated by applying a fluid structure interaction approach. A commercial Computational Fluid Dynamics (CFD) code is coupled to a computational structural program that solves the dynamic equations of the airfoil oscillations. The fluid governing equations are described in the Arbitrary Lagrangian Eulerian coordinates and solved with a moving mesh. A straightforward meshing technique is implemented in a subroutine called by the CFD code at each time step for updating the grid. The method is applied to a free pitch oscillating airfoil and to combined pitch and vertical oscillations known as the flutter instability. [ABSTRACT FROM AUTHOR]

This is the first part of a two part paper on flow around vibrating wind turbine airfoils. In this part 1, the unsteady, incompressible, viscous and laminar flow over a forced oscillating airfoil is computed using a method based on a commercial Computational Fluid Dynamics (CFD) code. Beforehand, the Navier-Stokes equations are solved for the unsteady flow around a NACA 0012 airfoil at a fixed 20° incidence and the low Reynolds numbers of 103 and 104 to check the reliability of the CFD computations. Then the flow around a pitching airfoil is simulated for prescribed values of the reduced frequency. The Navier-Stokes equations are expressed in ALE formulation and solved with moving mesh. The effects of the discretization scheme and the moving mesh technique are investigated. The hysteresis loops of the dynamic stall phenomenon are highlighted. [ABSTRACT FROM AUTHOR]

Abstract: We study the effect of nitrogen content in modulation-doped GaAs/GaAs1− x N x /GaAs/GaAlAs:(Si) quantum well using low-temperature photoluminescence spectroscopy. The samples were grown on GaAs (001) substrates by molecular-beam epitaxy with different nitrogen compositions. The variation of the nitrogen composition from 0.04% to 0.32% associated to the bi-dimensional electron gas gives a new interaction mode between the nitrogen localized states and the GaAs1− x N x /GaAs energies levels. The red-shift observed in photoluminescence spectra as function of nitrogen content has been interpreted in the frame of the band anticrossing model. [Copyright &y& Elsevier]

Abstract: We present a new method for evaluating relative active tectonics based on geomorphic indices useful in evaluating morphology and topography. Indices used include: stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), and index of mountain front sinuosity (Smf). Results from the analysis are accumulated and expressed as an index of relative active tectonics (Iat), which we divide into four classes from relatively low to highest tectonic activity. The study area along the southwest border of the Sierra Nevada in southern Spain is an ideal location to test the concept of an index to predict relative tectonic activity on a basis of area rather than a single valley or mountain front. The study area has variable rates of active tectonics resulting from the collision of Africa with Europe that has produced linear east–west anticlinal forms, as well as extension with variable vertical rates of normal faulting to about 0.5 m/ky. We test the hypothesis that areas of known, relatively high rates of active tectonics are associated with indicatives values of Iat. [Copyright &y& Elsevier]

Abstract: Navier–Stokes equations have fundamental properties such as the invariance under some transformations, called symmetries, which play an important role in the description of the physics of the equations (conservation laws, wall laws, …). It is essential that turbulence models do not violate these properties. An analysis of a large set of subgrid models, according to the respect of the symmetries of Navier–Stokes equations is then done. As this analysis reveals that only few of the existing models are consistent with the symmetries, a new class of compatible models is proposed. This class is refined such that the models also respect the second law of thermodynamics. Finally, it is shown that this thermodynamic requirement leads to the stability of the model. [Copyright &y& Elsevier]

Symmetries have an important role in turbulence. To some extent, they contain the physics of the equations (conservation laws, etc.), and it is essential that turbulence models respect them. However, as observed by Oberlack (Annual Research Briefs. Stanford University, Stanford 1997) and next by Razafindralandy and Hamdouni (Direct and Large-Eddy Simulation 6: Proceedings of the 6th International ERCOFTAC Workshop on Direct and Large-Eddy Simulation. Springer, Heidelberg, 2006) in the case of an isothermal fluid, only few subgrid stress tensor models preserve the symmetries of the Navier–Stokes equations. In this communication, we present the symmetries of the equations of a non-isothermal fluid flow and analyze some common subgrid stress tensor and flux models under the point of view of these symmetries. [ABSTRACT FROM AUTHOR]

Abstract: Symmetries, i.e. transformations which leave the set of the solutions of the Navier–Stokes equations unchanged, play an important role in turbulence (conservation laws, wall laws, …). They should not be destroyed by turbulence models. The symmetries of the heat convection equations are then presented, for a non-isothermal fluid. Next, common subgrid stress tensor and flux models are analyzed, using the symmetry approach. To cite this article: D. Razafindralandy, A. Hamdouni, C. R. Mecanique 335 (2007). [Copyright &y& Elsevier]