Miracle-dz/UniFAR-FTUs huggingface dataset:
Hierarchically mesostructured MIL-101 metal–organic frameworks: supramolecular template-directed synthesis and accelerated adsorption kinetics for dye removal

Hierarchically mesostructured MIL-101 metal–organic frameworks (MOFs) were successfully synthesized under solvothermal synthesis conditions by using the cationic surfactant cetyltrimethylammonium bromide as a supramolecular template. The mesostructured MIL-101 MOFs were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption isotherms at 77 K. The results suggest that the mesostructured MIL-101 MOFs obtained are composed of numerous MOF nanocrystals. Pore size distribution analyses of the as-synthesized MOF samples reveal that such mesostructured MIL-101 MOFs have well-defined trimodal pore size distributions showing simultaneous existence of meso- and macropore channel systems. Significantly, such hierarchically mesostructured MIL-101 exhibits remarkably accelerated adsorption kinetics for dye removal in comparison with the bulk MIL-101 crystals, which is due to unique hierarchically meso- and macropores created in the solid.
Dynamic Solvent Effects on Electron-Transfer Reactions

Electron-transfer processes in solution are among the most important reactions in chemistry and biology. The huge number of redox reactions of transition metal ions and complexes, many preparatively important oxidations and reductions of organic compounds, photosynthesis, and metabolism are only a few examples where electron-transfer reactions play a pivotal role. This ubiquity, as well as their relative simplicity, makes them excellent models for the study on a molecular level of chemical reactions in solution. A particularly important question in chemical reaction dynamics in solution is the influence of the solvent on the reaction rate. In this context one distinguishes between static and dynamic solvent effects. Static effects refer to the stabilization of reactants, transition state, and products, that is, how the solvent affects the free energies of these species and the energy of activation. This interpretation of solvent effects on all kinds of chemical reactions is well established. A more recent development is the investigation of the influence of solvent dynamics on the rate of a reaction. The transfer of an electron is usually thought to be triggered by a fluctuation of the dielectric polarization in the surrounding solvent. The dynamics of such fluctuations is determined by the finite response time of the orientational polarization of the solvent. Under certain conditions this dielectric response time can become the rate-determining factor of the reaction. In this article I intend to give a review of these modern developments in the theory and experimental study of electron-transfer processes. We shall see that solvent dynamics may lead to a whole plethora of phenomena in reaction dynamics. The concepts needed for their description are not limited to electron transfer but bear relevance to many other chemical reactions in solution.
Metal–organic frameworks and related materials for hydrogen purification: Interplay of pore size and pore wall polarity

The separation of hydrogen from other weakly adsorbing gases is a topic of high industrial relevance. Microporous materials, such as zeolites, metal–organic frameworks (MOFs), and nanoporous molecular crystals, hold much promise as adsorbent materials for adsorption-based hydrogen separation units. However, most experimental and theoretical studies that have been reported so far have focused on relatively few gas mixtures (mainly CO2/H2 and CH4/H2). In this work, the suitability of five materials (zeolite: silicalite; MOFs: Mg-formate, Zn(dtp), Cu3(btc)2; porous molecular crystal: cucurbit[6]uril) for the adsorption-based separation of carbon monoxide/hydrogen and oxygen/hydrogen mixtures is assessed using force-field based grand-canonical Monte Carlo simulations. The simulations are employed to predict single-component and mixture isotherms, as well as adsorption selectivities. Moreover, a detailed analysis of the solid-fluid interactions is carried out on an atomistic level. The choice of materials is motivated by their structural properties: four systems contain relatively narrow channels (diameters < 6.5 A), but differ in pore wall composition and polarity. The fifth system possesses coordinatively unsaturated metal sites, which can act as preferential adsorption sites for some guest molecules. The role of electrostatic interactions is fundamentally different for the two mixtures considered: for CO/H2 separation, the employment of polar adsorbents is beneficial due to the enhanced electrostatic interaction with carbon monoxide. On the contrary, an increased polarity of the pore wall tends to reduce the O2/H2 selectivity, because electrostatic interactions favour hydrogen over oxygen due to its larger quadrupole moment. In general, materials with narrow channels perform best in the separation of hydrogen from weakly adsorbing species, because the dispersive interactions are maximized in the channels. Moreover, they provide little space for the co-adsorption of hydrogen.
Surface energy and surface tension of liquid metal nanodrops

A unitary approach has been proposed for the calculation of surface energy and surface tension of nanoparticle being in equilibrium with its saturated vapor on both flat and curved surfaces at given temperature. The final equations involve parameters dependent on the type of premelting structure: bcc, fcc or hcp. The surface energy u and the surface tension  are the most important thermodynamic characteristics of the layer between the coexistent phases. These quantities, in turn, allow one to obtain other characteristics of the interface boundaries such as work of adhesion, edge angle of wetting, coefficient of spreading etc. The values of u and  are of special interest when studying the properties of nanoobjects (particles, bubbles, thin films) because the increase of surface contribution to the properties of the whole system becomes intrinsic. This communication deals with the calculation of surface energy and surface tension of nanoparticle held in equilibrium with its saturated vapor at constant temperature on the basis of proposed unitary approach. Let the nanoparticle be sphere of radius r corresponding to the equimolar dividing surface at which the autoadsorption, as known, is nil ( 0
Solid surface free energy components determination by the thin-layer wicking technique

A thin-layer wicking technique [1] and van Oss et al.'s [2] approach to interfacial free energy interactions were tested to determine the solid surface free energy components: apolar Lifshitz-van der Waals, yl,w y; and polar, electron donor, γ- y, and electron acceptor, γ+ y. For this purpose, the penetration rates of n-alkanes, diiodomethane, water, formamide, toluene and chloroform were measured. For these studies, silica, used for thin-layer chromatography, and α-Al2O3 were used as the model solids. It was found that both are strongly polar, electron donor solids with weak electron acceptor interactions. It is concluded that van Oss, Good et al.'S [2] approach to the interfacial free energy interactions and the thin-layer wicking technique are very useful for cxplaining many interfacial phenomena taking place in the dispersed systems. However, more experimental work using different systems is needed.
Spectrophotometric determination of cobalt (ii) in low concentrations using hydroxytriazene as selective chelating agents

The present work describes a selective, rapid and simple spectrophotometric method for the determination of cobalt (II) at trace levels using some selected hydroxytriazene. The method is based on the reaction of hydroxytriazene at pH 5.5 to 6.2, 6.0 to 6.8, 7.1 to 7.35, 7.3 to 7.9, 6.75 to 7.25 and 7.2 to 7.75 for hydroxytriazenes no (i), (ii), (iii), (iv), (v) and (vi) respectively and ethanol media with cobalt (II) to produce a highly absorbent yellow coloured chelate product with an absorption maximum at 393,397,417,406,410 and 412 nm for hydroxytriazenes no. (i), (ii), (iii), (iv), (v) and (vi), respectively. The reaction is instantaneous and the absorption remains stable for 24 Hrs. The average molar absorption coefficient were 1.1 x 10 4 , 1.2 x 10 4
The first examples of room temperature liquid crystal dimers based on cholesterol and pentaalkynylbenzene

In this article, we report the synthesis of the first examples of room temperature liquid crystal dimers based on cholesterol and pentaalkynylbenzene linked via flexible alkyl spacers. The thermal behaviour and mesomorphic properties of the newly synthesised compounds were investigated by differential scanning calorimetry, polarised optical microscopy and X-ray diffraction studies. All the synthesised dimers showed nematic (N*) phase at room temperature and exhibited excellent fluorescent emission properties. The steady-state anisotropy and fluorescence lifetime were measured in order to gain further insights into the supramolecular arrangement of these dimers.
Effect of substrate pre-treatment on microstructure and enhanced electrochromic properties of WO3 nanorod arrays

WO3 nanorod arrays (WNRAs) were successfully synthesized on an FTO substrate pre-coated with a layer of TiO2 seeds. The morphology and micro-structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The effect of substrate pre-treatment on electrochromic (EC) properties of as-prepared WNRAs was investigated in detail. Compared with those synthesized on WO3 seed layer, the WNRAs grown on TiO2 seed layer showed a large optical modulation (77.5%, at 660 nm) and high coloration efficiency (142.7 cm2 C−1) under the optimal preparation conditions. In addition, the influence of annealing temperature of the TiO2 seed layer on the EC performance was also discussed. More importantly, the WNRAs grown on the TiO2 seed layer presented good stability and strong adhesion to the FTO substrate during the test process.
Effect of ionic size on the structure of spherical double layers: a Monte Carlo simulation and density functional theory study

The effect of ionic size on the diffuse layer characteristics of a spherical double layer is studied using Monte Carlo simulation and density functional theory within the restricted primitive model. The macroion is modelled as an impenetrable charged hard sphere carrying a uniform surface charge density, surrounded by the small ions represented as charged hard spheres and the solvent is taken as a dielectric continuum. The density functional theory uses a partially perturbative scheme, where the hard sphere contribution to the one particle correlation function is evaluated using weighted density approximation and the ionic interactions are calculated using a second-order functional Taylor expansion with respect to a bulk electrolyte. The Monte Carlo simulations have been performed in the canonical ensemble. The detailed comparison is made in terms of zeta potentials for a wide range of physical conditions including different ionic diameters. The zeta potentials show a maximum or a minimum with respect to the polyion surface charge density for a divalent counterion. The ionic distribution profiles show considerable variations with the concentration of the electrolyte, the valency of the ions constituting the electrolyte, and the ionic size. This model study shows clear manipulations of ionic size and charge correlations in dictating the overall structure of the diffuse layer.
CdTe Thin Film Solar Cells: The CdS/SnO 2 Front Contact

Tin dioxide (SnO 2 ) coated glass is the commonly used substrate for thin film solar cells based on CdTe absorbers. We have investigated the properties of the CdS/SnO 2 interface by X-ray and ultraviolet photoelectron spectroscopy. SnO 2 coated glass substrates as used for solar cell preparation were cleaned by different procedures such as derinsing, sputtering, heating and annealing in oxygen atmosphere. Different surface properties with a strongly dependent number of defects in the SnO 2 band gap are identified. CdS films were deposited stepwise by thermal evaporation to determine the electronic interface properties for different surface preparation conditions. Comparative barrier heights at the CdSSnO 2 contact are found for most surface pretreatments. The Fermi level position in these cases is situated in the SnO 2 band gap. A different interface behaviour is determined for sputter cleaned SnO 2 surfaces, which is attributed to the formation of oxygen vacancies during sputtering and subsequent formation of an interfacial SnO x S y compound.
Effective parameters on selective catalytic hydrodeoxygenation of phenolic compounds of pyrolysis bio-oil to high-value hydrocarbons

Pyrolysis bio-oil is recognized as a renewable and carbon-neutral fuel which could be a potential alternative for depleting fossil fuels. However, bio-oil is highly oxygenated and needs to be upgraded prior to be used as fuel additive. Catalytic hydrodeoxygenation (HDO) is an efficient technique for bio-oil upgrading. The reaction pathway for HDO of bio-oil is unknown since it is a mixture of hundreds of different compounds. The study on mechanism of transformation of these compounds could be helpful to propose an overall pathway for HDO of bio-oil. Phenols which are derived from pyrolysis of lignin fraction of biomass are considered as attractive model compounds for study of bio-oil HDO since they are highly stable in HDO reaction. Reaction pathway and product selectivity in HDO of phenols are highly affected by type of catalyst promoters and supports, catalyst preparation procedure, solvent type, chemicals used as co-feed and operating conditions (i.e., temperature and pressure). The effects of these factors on selective production of high-value hydrocarbons of aromatics and alicyclics from HDO of phenol, cresol, guaiacol and anisole are discussed in this review.
Thin film composite sodium alginate membranes for dehydration of acetic acid and isobutanol

Dehydration of widely used organic solvents such as acetic acid (AA) and isobutanol (IB) is challenging tasks, which form close boiling mixtures with water. Sodium alginate (SA) thin film composite membranes were prepared and crosslinked with 2,4-toluene diisocyanate (TDI) and glutaraldehyde for dehydration of IB and AA/water mixtures through pervaporation (PV). The crosslinked and uncrosslinked SA composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and universal testing machine for intermolecular interactions, crystalline nature, thermal stability, surface morphology, and tensile strength, respectively. At a feed composition of 98 wt % IB and 95 wt % AA aqueous solutions, the TDI crosslinked SA composite membrane exhibited separation factors of 3229 and 708 with reasonable fluxes of 0.021 and 0.012 kg m−2 h−1, respectively. The results obtained in the study for IB and AA systems were compared with other SA membranes reported in the literature. The membranes appeared to have potential for commercial PV ability to dehydrate the solvents up to desirable purity levels (>99%) and feasibility of preparing them in a composite form which would enable scale-up into modular configurations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40018.
Effects of low‐frequency modulation on rf discharge chemical vapor deposition

Low‐frequency square‐wave modulation of a rf discharge in silane diluted with a rare gas brought about an improvement in the deposition rate of amorphous hydrogenated silicon films and in the film quality as well as a drastic suppression of powder concentration in the discharge space. These results can be explained by a SiH3 density in the modulated discharge that is high compared to that without modulation, because of the electron density enhancement resulting from the modulation and also because the lifetime of SiH3 radicals is much longer than those of SiHn radicals (n=0–2).
Reductive dechlorination of preexisting sediment polychlorinated biphenyls with long‐term laboratory incubation

Abstract—The dechlorination potential of polychlorinated biphenyl (PCB)‐contaminated sediments from the St. Lawrence River was investigated in laboratory incubations over a 39‐month period. During the first 4 months, dechlorination reduced the average total chlorines in the General Motors 001 sediments from 3.2 to 2.5 per biphenyl, an additional 22% beyond the in situ level, for an overall 36% reduction from the original Aroclor 1248 contaminant. With continued incubation, however, an additional dechlorination of a single peak 2,4′,5+2,4,4′‐chlorobiphenyl ensued after a lag that reduced the average chlorines from 2.5 to 2.4. After this, there was no further transformation until the end of incubation. The extent of dechlorination and congener pattern of Aroclor 1248‐spiked sediments were similar to those of the native sediments after a comparable period of time despite differences in sediment sources and starting congener composition. The results indicate that most dechlorination occurs during a relatively short period of the initial rapid phase and any further transformation, if it occurs, would be extremely slow, and its contribution to the total dechlorination may not be significant.
Calcium carbonate precipitation using new segmented flow tubular reactor

A new segmented flow tubular reactor for the continuous production of powders was used to synthesize calcium carbonate by precipitation. This new reactor uses a nonmiscible phase (air in most cases) to create individual microvolumes of the reacting mixture or suspension ensuring that a plug-flow regime is maintained. In a microvolume, poor micromixing can be avoided and the homogeneity in reaction conditions is increased better than in larger volumes, leading to a better control of powder characteristics. Calcium carbonate with controlled characteristics could be precipitated continuously using this new segmented flow tubular reactor. Pure calcite could be obtained in the tubular reactor by segmenting a Ca2+ solution with a reactive CO2/NH3 gas mixture. This synthesis process is very promising for industrial production since the scale-up should easily be achieved by multiplying the number of tubes working in parallel.
Definition of the uptake mechanism and sub- cellular localisation profile of emissive lanthanide complexes as cellular optical probes

A series of experiments has been undertaken in order to gain a greater understanding of the cellular uptake and localisation behaviour of emissive lanthanide complexes as cellular stains or probes. Out of a large number of structurally related complexes characterised recently, a set of seven representative examples has been examined in detail, containing either tetraazatriphenylene or azaxanthone-based sensitising chromophores. Intracellular localisation profiles and cellular uptake and egress behaviour have been studied by microscopy and flow cytometry. Typically, the maximum intracellular concentration was of the order of 0.4 mM, or about 109 complexes per cell. The complexes studied were generally not toxic and did not perturb the mitochondrial membrane potential. A common uptake mechanism of macropinocytosis has been identified. A generalisation of trends in behaviour, and structure–activity relationships is presented, and the implications for future probe design discussed.
Kinetic, Isotherm and Thermodynamic Studies of the Biosorption of Cadmium (II) by Snail (Lymnaea rufescens) Shell

The biosorption of C d(II) from dilute aqueous so lution using snail (Lymnaea rufescens) s hell as the biosorbent has been studied. The biosorption study was carried out as a function of pH, contact time and initial metal ion co ncentration at the temperature of 27 C. The residual Cd(II) in s olution was o determined using atomic absorption spectrophotometer. T he study o n pH showed that t he biosorption is pH dependent. The o ptimum pH range for t he b iosorption i s pH 2 - 8. The st udy also showe d that the biosorption i s time d ependent. Maximum biosorption of 99.9% was ob tained after 5 0 min o f th e process. Kinetic stud y s howed that the pseudo-second order ra te e quation better d escribed the biosorption p rocess. The adsorption isotherms obtained fitted well into the Freundlich and Langmuir isotherms. The Freundlich equation obtained is Log √ = 0. 7577 logCe - 0.5025, while the Langmuir equation obtained is 1/√ = 0.0009/Ce - 0.0605. The correlation f actors are 0. 9986 and 0. 9991, while t he standard devi ation va lues are 0.0188 and 0.0016, respectively. The f ree energy change obtained for t he b iosorption of Cd(II) at the temperature of 310K, initial Cd(II) concentration of 100mg/L and pH 7 is - 3.5416 kJmol . These results -1
Incorporation of solvent effects into density functional calculations of molecular energies and geometries

In this paper, we present the implementation of the ‘‘conductorlike screening model’’ (COSMO) into the density functional program DMol. The electronic structure and geometry of the solute are described by a density functional method (DFT). The solute is placed into a cavity which has the shape of the solute molecule. Outside of the cavity, the solvent is represented by a homogeneous dielectric medium. The electrostatic interaction between solute and solvent is modeled through cavity surface charges induced by the solvent. The COSMO theory, based on the screening in conductors, allows for the direct determination of the surface charges within the SCF procedure using only the electrostatic potentials. This represents the major computational advantage over many of other reaction field methods. Since the DMol/COSMO energy is fully variational, accurate gradients with respect to the solute coordinates can be calculated for the first time, without any restriction on the shape of the cavity. The solvation energi.
Solubility mechanisms of water in basalt melt at high pressures and temperatures: NaCaAlSi2O7−H2O as a model

The solubility mechanism of HrO in melt of NaCaAlSi2O, compositi,on (Sm melt) has been determined at high pressures and temperatures by Raman spectroscopy. The NacaAlSi2o, composition was chosen because its melt has an Al content and a ratio ef nq1[ridging oxygen to tetrahedral cation (NBO/T : 0.67) simil4l to those in basalt (Al2O, : 13-18 wt. p€rc€nt, NBO/T:0.6-0.8). water dissolves in sm melt to form oH groups associated with si4* and probably Na* or Caz' ot both. There is no spectroscopic evidence for Al-oH, Al-H, or Si-H bonds or for molecular HrO or Hr. The Raman spectra of both anhydrous and hydrous Sm melt indicate that both melts have structural units with an average NBO/T of 2, l, and 0 (chains, sheets, and three-dimensional networD. As the water content of the melt is increased, the chain and sheet units in the melt become more aluminous, whereas the three-dimensional network units show an increase of Si/(Si + Al). The bulk NBO/T of hydrous melt and, by imFlication" hydrous basalt melt has increased, however, relative to its anhydrous equivalent. on the basis of the results on quenched melt of NacaAlSiroz + Hro and NaAlSiro, + HrO compositions, we suggest that activity coeftsients of cations that are sensitive to NBO/T of the melt (e.g., transition metals and rare-earth trace elements) will decrease at a slower rate with increasing water content of basalt melt than if the melts were andesitic or granitic in composition. We also suggest that the viscosity of basalt melt is less sensitive to water content than the viscosity of more acidic melts (e.g., andesite and granite).