Adsorption behavior of iron phthalocyanine at the initial stage on Cu(100) surface

The adsorption behavior of iron phthalocyanine (FePc) on the Cu(100) surface at the initial stage has been investigated by combining scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. At low coverage, FePc molecules deposited on the sample surface at room temperature tend to adsorb dispersedly with their molecular planes parallel to the crystallographic directions of the substrate. Another interesting STM observation for the sub-monolayer coverage is that the molecular axes of FePc are aligned along [037] (as well as $\left[0\overline{3}7\right]$) azimuth. At the monolayer coverage and elevated temperature, two types of ordered structures are observed. The FePc adsorption sites for the experimentally observed two distinct ordered domains have been revealed through DFT calculations. With further increasing the coverage, molecular clusters are formed particularly near the step edges.     

Effects of Hall current on unsteady MHD flows of a second grade fluid

The aim of this present paper is to construct exact solutions corresponding to the motion of magnetohydrodynamic (MHD) fluid in the presence of Hall current, due to cosine and sine oscillations of a rigid plate as well as those induced by an oscillating pressure gradient. A uniform magnetic field is applied transversely to the flow. By using Fourier sine transform steady state and transient solutions are presented. These solutions satisfy the governing equations and all associated initial and boundary conditions. The results for a hydrodynamic second grade fluid can be obtained as a limiting case when B ₀ → 0 and for a Newtonian fluid when α ₁ → 0.     

Observation of postsoliton expansion following laser propagation through an underdense plasma

The expansion of electromagnetic postsolitons emerging from the interaction of a 30 ps, 3×101? W?cm?2 laser pulse with an underdense deuterium plasma has been observed up to 100 ps after the pulse propagation, when large numbers of postsolitons were seen to remain in the plasma. The temporal evolution of the postsolitons has been accurately characterized with a high spatial and temporal resolution. The observed expansion is compared to analytical models and three-dimensional particle-in-cell results, revealing a polarization dependence of the postsoliton dynamics.     

Crystallographic report: 1,1‐Diphenyl‐3‐(triphenylgermyl)‐3‐(4‐chlorophenyl) propanol

The germanium atom in [(C₆H₅)₃GeCH(4‐ClC₆H₄)CH₂C(C₆H₅)₂OH] is in a distorted tetrahedral geometry. Steric hindrance precludes O? H···O intra‐ or inter‐molecular bonding. Copyright © 2005 John Wiley & Sons, Ltd.     

Towards ultrafine TiO2 nanocrystal at room temperature

Ultrafine titanium dioxide (TiO₂) nanocrystal has attracted enormous interest due to their unusual quantum and surface effects. Here, we propose a facile route to synthesize ultrafine anatase nanocrystal at room temperature via an aqueous sol–gel method using lactic acid (LA) and acetylacetone (Acac) as double chelators. Transmission electron microscopy (TEM) and size analyzer confirmed that TiO₂ nanocrystal in precursor possessed an average size of ~3 nm with a narrow size distribution. Crystal structure characterized by TEM and X-ray diffraction (XRD) indicated that TiO₂ nanocrystal to be anatase phase. The results of field emission scanning electron microscopy (FE-SEM) and BET surface area exhibited that TiO₂ xerogel powder had mono-dispersed particles size and large BET surface area up to 90 m²/g.     

Synthesis and Characterization of Polyimide‐Silica Hybrids: Effect of Matrix Polarity on the Mechanical and Thermal Properties

Polyimide‐silica hybrid materials have been prepared through the sol‐gel process by mixing various proportions of tetraethoxysilane (TEOS) with polyamic acids (PAAs). Two types of PPAs were employed. The first was obtained by reacting an equimolar mixture of oxydianiline (ODA) and pyromellitic dianhydride (PMDA) in dimethylactamide (DMAc) as solvent. The second was prepared using a mixture of ODA and 2,2‐Bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane (6F‐OHDA) in molar ratio 9:1, respectively and reacting with a stoichiometric amount of PMDA in DMAc. Polyamic acids were converted to polyimides and a sol‐gel reaction proceeded simultaneously by heating the hybrid films to 300°C. The hydroxyl groups from 6F‐OHDA allows the secondary bonding between the polyimide and growing silica phase and thus retard the gross phase separation. Only the 10 mol% addition of 6F‐OHDA in the polyimide chain resulted in a drastically different microstructure for the resulting hybrids. SEM, stress‐strain analysis, temperature variation of storage and loss modulus, and thermal stability were used to characterize the hybrid materials. Properties of both types of hybrids have been compared and related to the two different types of structures of polyimides used in the preparation of the hybrids.     

Rapid prototyping of electrochemical energy storage devices based on two dimensional materials

Rapid prototyping methods such as additive manufacturing (three dimensional printing) and laser scribing have attracted much attention for manufacturing next-generation electrochemical energy storage devices because of their simplicity, low cost, medium throughput, and ability to prepare electrodes with unique form factors and multiple functionalities, such as stretchability, flexibility, and wearability. Of the wide array of potential active materials that can be used for energy storage, two dimensional materials such as graphene, MXenes, and MoS₂ have exceptionally high conductive surface areas and are attractive candidates for printing thick, high loading supercapacitors and batteries. In this brief review, we highlight recent progress and major challenges which must be overcome to make these manufacturing approaches and the resulting printed devices commercially viable.     

Characterization of Surfactant-Diblock Copolymer Interactions and Its Thermodynamic Studies

The interaction of nonionic diblock copolymer poly(ethylene oxide butylene oxide) (E₆₂B₂₂) with a cationic surfactant cetyl trimethyl ammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulphate (SDS) were studied using surface tension, conductivity, and dynamic laser light scattering techniques. Surface tension measurements were used to determine critical micelle concentration and thereby its free energy of adsorption (ΔG_ads), free energy of micellization (ΔG_m), surface excess concentration (Γ), and minimum area per molecule (A). Conductivity measurements were used to determine critical micelle concentration (CMC) critical aggregation concentration (CAC) at different temperatures, enthalpy of micellization (ΔH_m), free energy of micellization and entropy of micellization (ΔS_m). Changes in physicochemical properties of the micellized block copolymer were studied by using dynamic laser light scattering. The effect of surfactant on the size and properties of block copolymer has also been discussed.     

Mössbauer study of corrosion of mild steel induced by acid rain

Room temperature corrosion studies have been made on the rust of commercially available mild steel in a simulated acid rain environment using the method of transmission Mössbauer spectroscopy. The main corrosion products identified are α-FeOOH, γ-FeOOH, and a product with unfamiliar parameters which seems to be amorphous in nature (being very large linewidth ?2.5 mm/s) and may be considered as an intermediate phase. A small amount of γ-Fe₂O₃ (6–8%) is also observed.     

Depolymerization Study of Pakistani Coal in a Hydrogen Atmosphere. Effect of Operating Conditions

A Pakistani coal was de‐polymerized/liquefied in toluene in a 1000 mL micro autoclave. Experiments have been performed in a pool of hydrogen under varying operating conditions of temperature, residence time, hydrogen pressure (cold), coal/solvent ratio and coal particle size. A pronounced effect of all these process variables has been noted on the yields of liquefied products, i.e., THF solubles, n‐pentane solubles, and n‐pentane insolubles. Extraction temperature of 450 °C, residence time of 1 hour, hydrogen pressure of 30 kgf/cm², coal/solvent ratio of 1:2 and coal particle size of 53–45 μm were found optimum for maximum conversion of Pakistani coal into liquefied products.