Efficient removal of anionic dye by protonated APTES modified hydrochar: The effect of cold-activation

The study focused on determining the effect of acidic and basic cold activation on hydrochar (HC) for the removal of methyl orange (MO). HC was prepared by hawthorn seeds (HS) under hydrothermal carbonization. HC was cold-activated with HCl and NaOH, respectively, and they were grafted with aminopropyltriethoxysilane (APTES) and protonated to obtain AHC-N⁺ (acid-activated and modified HC) and BHC-N⁺ (base-activated and modified HC) to determine the effect of acidic and basic activation. They were characterized by elemental analysis, IR, thermal analysis, zeta potential, N₂ adsorption–desorption measurements, and SEM–EDX analysis. The prepared adsorbents displayed MO adsorption due to abundant protonated amine groups. BHC-N⁺ showed higher MO adsorption than AHC-N⁺. The result showed that more protonated APTES groups grafted on the surface of HC via NaOH activation. The obtained data had a good fitting with the Langmuir isotherm and pseudo-second-order kinetic. The maximum adsorption capacity of BHC-N⁺ was 250.38 mg g⁻¹. The adsorption mechanism could be attributed to the electrostatic interactions between MO and protonated amine groups of APTES and hydrogen bonding.     

Calculations of Isoelectronic Series of He Using Noninteger n‐Slater Type Orbitals in Single and Double Zeta Approximations

Using integer and noninteger n-Slater type orbitals in single- and double-zeta approximations, the Hartree-Fock-Roothaan calculations were performed for the ground states of first ten cationic members of the isoelectronic series of He atom. All the noninteger parameters and orbital exponents were fully optimized. In the case of noninteger n-Slater type orbitals in double zeta basis sets, the results of calculations obtained are more close to the numerical Hatree-Fock values and the average deviations of our ground state energies do not exceed 2×10^－6 hartrees of their numerical results.     

A nonnormal look at polychoric correlations: modeling the change in correlations before and after discretization

Two algorithms for establishing a connection between correlations before and after ordinalization under a wide spectrum of nonnormal underlying bivariate distributions are developed by extending the iteratively found normal-based results via the power polynomials. These algorithms are designed to compute the polychoric correlation when the ordinal correlation is specified, and vice versa, along with the distributional properties of latent, continuous variables that are subsequently ordinalized through thresholds dictated by the marginal proportions. The method has broad applicability in the simulation and random number generation world where modeling the relationships between these correlation types is of interest.     

Nitrosylation of Nitric‐Oxide‐Sensing Regulatory Proteins Containing [4Fe‐4S] Clusters Gives Rise to Multiple Iron–Nitrosyl Complexes

The reaction of protein‐bound iron–sulfur (Fe‐S) clusters with nitric oxide (NO) plays key roles in NO‐mediated toxicity and signaling. Elucidation of the mechanism of the reaction of NO with DNA regulatory proteins that contain Fe‐S clusters has been hampered by a lack of information about the nature of the iron‐nitrosyl products formed. Herein, we report nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT) calculations that identify NO reaction products in WhiD and NsrR, regulatory proteins that use a [4Fe‐4S] cluster to sense NO. This work reveals that nitrosylation yields multiple products structurally related to Roussin's Red Ester (RRE, [Fe₂(NO)₄(Cys)₂]) and Roussin's Black Salt (RBS, [Fe₄(NO)₇S₃]. In the latter case, the absence of ³²S/³⁴S shifts in the Fe?S region of the NRVS spectra suggest that a new species, Roussin's Black Ester (RBE), may be formed, in which one or more of the sulfide ligands is replaced by Cys thiolates.     

Heavy metal contamination in street dusts of Istanbul (Pendik to Levent) E-5 highway

Street dust composition is an important environmental parameter that should be considered in investigations of environmental pollution originating from traffic. In this study, fifty-six samples of street dusts were collected during the period December 2003-April 2004 from Pendik to Levent on E-5 highway in Istanbul, Turkey. Analyses were determined by graphite furnace atomic absorption spectrometry after digestion using USEPA, 1996 (Method 3050B). The mean concentration levels of Pb, Mn, Zn, Ni, Cd and Cu were found to be 368.3, 747.8, 431.2, 27.1, 0.3 and 191.1 microg/g respectively. Pb, Cu, Zn and Mn mean concentrations in studied areas were higher than levels of these heavy metals according to USEPA (1992) and Republic of Turkey Ministry of Environment and Foresty (2003). Highly significant correlations except for Mn were found between the number of vehicles and heavy metal concentrations.     

Deformation Driven Homogenization of Fracturing Solids

The paper discusses numerical formulations of the homogenization for solids with discrete crack development. We focus on multi–phase microstructures of heterogeneous materials, where fracture occurs in the form of debonding mechanisms as well as matrix cracking. The definition of overall properties critically depends on the developing discontinuities. To this end, we extend continuous formulations [1] to microstructures with discontinuities [2]. The basic underlying structure is a canonical variational formulation in the fully nonlinear range based on incremental energy minimization. We develop algorithms for numerical homogenization of fracturing solids in a deformation–driven context with non–trivial formulations of boundary conditions for (i) linear deformation and (ii) uniform tractions. The overall response of composite materials with fracturing microstructures are investigated. As a key result, we show the significance of the proposed non–trivial formulation of a traction–type boundary condition in the deformation–driven context. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phonon density of states in epitaxial FE/CR(0 0 1) superlattices

Incoherent nuclear resonant absorption of synchrotron radiation at the 14.413 keV nuclear resonance of ⁵⁷Fe was employed to measure directly the Fe-projected (partial) phonon density of states (DOS) in epitaxial FeCr(0 0 1) superlattices and in an ⁵⁷Fe_0.03Cr_0.97(0 0 1) alloy film MBE-grown on MgO(0 0 1). The measurements were performed at 300 K with 2.3 meV energy resolution around 14.413 keV. At the interfaces, longitudinal vibrations of Fe atoms are suppressed, and a strong resonance phonon mode appears near 23 meV. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sound velocities of compressed Fe3C from simultaneous synchrotron X‐ray diffraction and nuclear resonant scattering measurements

The applications of nuclear resonant scattering in laser‐heated diamond anvil cells have provided an important probe for the magnetic and vibrational properties of ⁵⁷Fe‐bearing materials under high pressure and high temperature. Synchrotron X‐ray diffraction is one of the most powerful tools for studying phase stability and equation of state over a wide range of pressure and temperature conditions. Recently an experimental capability has been developed for simultaneous nuclear resonant scattering and X‐ray diffraction measurements using synchrotron radiation. Here the application of this method to determine the sound velocities of compressed Fe₃C is shown. The X‐ray diffraction measurements allow detection of microscale impurities, phase transitions and chemical reactions upon compression or heating. They also provide information on sample pressure, grain size distribution and unit cell volume. By combining the Debye velocity extracted from the nuclear resonant inelastic X‐ray scattering measurements and the structure, density and elasticity data from the X‐ray diffraction measurements simultaneously obtained, more accurate sound velocity data can be derived. Our results on few‐crystal and powder samples indicate strong anisotropy in the sound velocities of Fe₃C under ambient conditions.     

Characterizations of Riesz spaces with b-property

A Riesz space E is said to have b-property if each subset which is order bounded in E^~~ is order bounded in E. The relationship between b-property and completeness, being a retract and the absolute weak topology |σ|(E^~, E) is studied. Perfect Riesz spaces are characterized in terms of b-property. It is shown that b-property coincides with the Levi property in Dedekind complete Frechet lattices.      

Multiscale Modeling of Nanocrystalline Materials: A Variational Approach

This paper presents a variational multi-scale constitutive model in the finite deformation regime capable of capturing the mechanical behavior of nanocrystalline (nc) fcc metals. The nc-material is modeled as a two-phase material consisting of a grain interior (GI) phase and a grain boundary (GB) phase. A rate-independent isotropic porous plasticity model is employed to describe the GB phase, whereas a crystal-plasticity model which accounts for the transition from partial dislocation to full dislocation mediated plasticity is employed for the GI phase. Assuming the rule of mixtures, the overall behavior of a given grain is obtained via volume averaging. The scale transition from a single grain to a polycrystal is achieved by Taylor-type homogenization. It is shown that the proposed model is able to capture the inverse Hall-Petch effect. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)