Quantum Chemical and Corrosion Inhibition Studies of (4-Chlorophenyl)-N-(4-Methylphenyl) Nitrone

The compound (4-chlorophenyl)-N-(4-methylphenyl) nitrone (4CPNMPN) has been selected as one of the new nitrone derivative for our study. The molecular structure of the compound was investigated based on frontier orbital analysis and natural bond orbital (NBO) theory. The present work also focuses on the inhibition efficiency of the compound. It is an attempt to find the correlation between the molecular structure of the compound and possible behaviour like corrosion inhibitors. The NBO analysis and the values of electric dipole moment (μ) of the investigated molecule were computed using DFT calculations. The molecule orbital contributions were studied by using the total (TDOS) density of states. The strong evidences that the compound can be used as an efficient nonlinear optical (NLO) of 4CPNMPN were demonstrated by considerable polarizability and hyperpolarizability values obtained at DFT levels.     

Insight into 3D micro‐CT data: exploring segmentation algorithms through performance metrics

Three‐dimensional (3D) micro‐tomography (µ‐CT) has proven to be an important imaging modality in industry and scientific domains. Understanding the properties of material structure and behavior has produced many scientific advances. An important component of the 3D µ‐CT pipeline is image partitioning (or image segmentation), a step that is used to separate various phases or components in an image. Image partitioning schemes require specific rules for different scientific fields, but a common strategy consists of devising metrics to quantify performance and accuracy. The present article proposes a set of protocols to systematically analyze and compare the results of unsupervised classification methods used for segmentation of synchrotron‐based data. The proposed dataflow for Materials Segmentation and Metrics (MSM) provides 3D micro‐tomography image segmentation algorithms, such as statistical region merging (SRM), k‐means algorithm and parallel Markov random field (PMRF), while offering different metrics to evaluate segmentation quality, confidence and conformity with standards. Both experimental and synthetic data are assessed, illustrating quantitative results through the MSM dashboard, which can return sample information such as media porosity and permeability. The main contributions of this work are: (i) to deliver tools to improve material design and quality control; (ii) to provide datasets for benchmarking and reproducibility; (iii) to yield good practices in the absence of standards or ground‐truth for ceramic composite analysis.     

Synthesis,Growth and Spectroscopic Studies of Piperazinium Paranitrophenolate Monohydrate Crystals

A new piperazinium 4-nitro phenolate monohydrate single crystal (PNP) was grown by employing the solution growth technique piperazine and 4-nitrophenol, were the source material used for the growth, acetonitrile is used as solvent. The grown crystal was characterized by Single X-ray analysis and it shows that piperazinium 4-nitrophenol monohydrate crystallizes in the monoclinic space group P2 1/c, with cell parameters a=10.902 5(4) Å, b=6.226 1(3) Å, c=14.031 8(5) Å, and z=4. The lattice parameters of the substances were also determined by using powder diffraction methods. The functional groups are identified by using FTIR spectral analysis. The absorbance of title compound were analyzed using UV-Vis spectra. The thermo analytical properties of the crystal were studied using TG, DTA.     

Use of chlorinated carbon and silicon precursors for epitaxial growth of 4H‐SiC at very high growth rates

A possibility to apply the advantages of chlorinated carbon precursors, which had been previously used in low‐temperature epitaxial growth of 4H‐SiC, to achieve very high growth rates at higher growth temperatures was investigated. Silicon tetrachloride was used as the silicon precursor to suppress gas‐phase homogeneous nucleation. The temperature increase from 1300 °C (which is the temperature of the previously reported low‐temperature halo‐carbon epitaxial growth) to 1600 °C enabled an increase of the precursor flow rates and consequently of the growth rate from 5 to more than 100 μm/h without morphology degradation. High quality of the epilayers was confirmed by low‐temperature photoluminescence spectroscopy and time‐resolved luminescence. No evidences of homogeneous nucleation were detected, however, liquid Si droplet formation on the epilayer surface seems to remain a bottleneck at very high growth rate. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Finite strain stress fields near the tip of an interface crack between a soft incompressible elastic material and a rigid substrate

We present a numerical study of finite strain stress fields near the tip of an interface crack between a rigid substrate and an incompressible hyperelastic solid using the finite element method (FEM). The finite element (FE) simulations make use of a remeshing scheme to overcome mesh distortion. Analyses are carried out by assuming that the crack tip is either pinned, i.e., the elastic material is perfectly bonded (no slip) to the rigid substrate, or the crack lies on a frictionless interface. We focus on a material which hardens exponentially. To explore the effect of geometric constraint on the near tip stress fields, simulations are carried out under plane stress and plane strain conditions. For both the frictionless interface and the pinned crack under plane stress deformation, we found that the true stress field directly ahead of the crack tip is dominated by the normal opening stress and the crack face opens up smoothly. This is also true for an interface crack along a frictionless boundary in plane strain deformation. However, for a pinned interface crack under plane strain deformation, the true opening normal stress is found to be lower than the shear stress and the transverse normal stress. Also, the crack opening profile for a pinned crack under plane strain deformation is completely different from those seen in plane stress and in plane strain (frictionless interface). The crack face flips over and the tip angle is almost tangential to the interface. Our results suggest that interface friction can play a very important role in interfacial fracture of soft materials on hard substrates.     

Probing temperature-sensitive behavior of pNIPAAm-coated iron oxide nanoparticles using frequency-dependent magnetic measurements

Ferromagnetic iron oxide nanoparticles of about 33 nm in diameter were synthesized by high-temperature decomposition of an iron-oleate complex, using octadecene as the solvent. These particles were subsequently coated with polyN-isopropylacrylamide (pNIPAAm) by a surfactant exchange method. Temperature-sensitive behavior of these particles was studied using ac susceptibility and dynamic light scattering (DLS) measurements. Shifts in the imaginary part of the ac susceptibility are correlated with swelling and collapse of pNIPAAm as a function of temperature.     

Strong CH⋅⋅⋅Halide Hydrogen Bonds from 1,2,3‐Triazoles Quantified Using Pre‐Organized and Shape‐Persistent Triazolophanes

The structures associated with halide (F^?, Cl^?, Br^?) complexation inside CH hydrogen‐bonding macrocyclic receptors, called triazolophanes, are characterized using density functional theory (DFT). The associated binding energies in the gas and solution phases are evaluated. The ruffles in the empty triazolophane become smoothed‐out upon Cl^?‐ and Br^?‐ion binding directly into the middle of the cavity. The largely pre‐organized cavity morphs into an elliptical shape to facilitate shorter hydrogen bonds in the north and south regions and longer ones west and east. The smaller F^? ion sits in, and flattens‐out, only the north (or south) region. The 1,2,3‐triazoles show shorter CH???Cl^? contacts than for the phenylenes. Both Cl^? and Br^? show the same binding geometries but Cl^? has a larger binding energy consistent with its stronger Lewis basicity. Model triads were used to decompose the overall binding energy into those of its components. In the course of this triad analysis, anion polarization was identified and its contribution to the triad???Cl^? binding energy estimated. Consequently, the binding energies for the individual aryl units within the comparatively non‐polarized triazolophanes were estimated. The 1,2,3‐triazoles are twice as strong as the phenylenes thus contributing most of the interaction energy to Cl^?‐ion binding. Therefore, the 1,2,3‐triazoles appear to approach the hydrogen bond strengths of the NH donors of pyrrole units.     

Lenalidomide,an antineoplastic drug,and its hemihydrate

The crystal structures of lenalidomide [systematic name: (RS)‐3‐(4‐amino‐1‐oxoisoindolin‐2‐yl)piperidine‐2,6‐dione], C₁₃H₁₃N₃O₃, (I), an antineoplastic drug, and its hemihydrate, C₁₃H₁₃N₃O₃·0.5H₂O, (II), have been determined by single‐crystal X‐ray diffraction analysis. The overall conformation of the molecule defined by the orientation of the two ring portions, viz. pyridinedione and isoindolinone, is twisted in both structures. The influence of the self‐complementary pyridinedione ring is seen in the crystal packing of both structures through its involvement in forming hydrogen‐bonded dimers, although alternate dione O atoms are utilized. An extensive series of N—H...O hydrogen bonds link the dimers into two‐dimensional supramolecular arrays built up from infinite chains. The water molecule in (II) has a cohesive function, connecting three lenalidomide molecules by hydrogen bonds. The significance of this study lies in the analysis of the interactions in these structures and the aggregations occurring via hydrogen bonds in the hydrated and dehydrated crystalline forms of the title compound.     

Dynamic pricing of multiple home delivery options

Online grocers accept delivery bookings and have to deliver groceries to consumers’ residences. Grocery stores operate on very thin margins. Therefore, a critical question that an online grocery store needs to address is the cost of home delivery operations. In this paper, we develop a Markov decision process-based pricing model that recognizes the need to balance utilization of delivery capacity by the grocer and the need to have the goods delivered at the most convenient time for the customer. The model dynamically adjusts delivery prices as customers arrive and make choices. The optimal prices have the following properties. First, the optimal prices are such that the online grocer gains the same expected payoff in the remaining booking horizon, regardless of the delivery option independently chosen by a consumer. Second, with unit order sizes, delivery prices can increase due to dynamic substitution effects as there is less time left in the booking horizon.     

A Convenient Category of Locally Preordered Spaces

As a practical foundation for a homotopy theory of abstract spacetime, we extend a category of certain compact partially ordered spaces to a convenient category of “locally preordered” spaces. We show that our new category is Cartesian closed that the forgetful functor to the category of compactly generated spaces creates all limits and colimits.