Miracle-dz/UniFAR-FTUs huggingface dataset:
Synthesis of silver nanocrystals by a modified polyol method

A modification of the polyol method has been shown to result in improved efficiency and enhanced kinetics for the synthesis of silver nanocrystals when compared with the traditional polyol method. The Ag nanocrystals produced were characterized using X-ray diffraction and transmission electron microscopy. Accordingly, the exhibited Ag crystal structure, corresponding lattice constants, and resultant particle sizes were determined by these means. In addition, using Fourier transform infrared spectroscopy, it was found that a solid-state reaction between the AgNO3 and the Poly (vinylpyrrolidone) (PVP) takes place prior to their dissolution in ethylene glycol. Moreover, when crystals grow under total rest conditions, they do not develop a spherical morphology as in the traditional polyol method, but a well-defined geometric shape showing preferential crystallographic growth directions. Under the experimental conditions of this work, the exhibited nanocrystal shapes were quasi-planar hexagonal. Apparently, PVP interacts with the FCC crystal structure promoting growth on the {100} preferential direction by playing the role of an atomic arranger. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
27-Ald triterpenoid saponins from adina rubella

Four new triterpenoid saponins were isolated from the roots of Adina rubella Hance. They were characterized as adinaic acid 3β-[α-L-rhamnopyranosyl(12)-β-D-glucopyranosyl(12)-β-D-glucurono-pyranoside-6-O-methyl ester]-2-O-β-D-glucopyranoside, adinaic acid 3β-O-[a-L-rhamnopyranosyl(12)-β-D-glucopyranosyl(12)-β-D-glucuronopyranosid-6-O-butyl ester]-28-O-β-D-glu-copyranoside, adinaic acid 3β-O-[β-D-glucopyranosyl(12)-β-D-glucopyranosyl]-(28 l)-β-D-glucopyranosyl(16)-β-D-glucopyranosyl ester, 27-hydroxyursolic acid 3β-O-[α-L-rhamnopyranosyl (1 2)-β-D-glucopyranosyl(12)-β-D-glucuronopyranoside-6-O-methyl ester]-28-O-β-D-glucopyranoside. Their structures wen elucidated by spectral methods, specially with the aid of 2D NMR techniques. Their complete assignments of the 1H and 13C NMR signals were carried out.
Magnetoliposomes for controlled drug release in the presence of low-frequency magnetic field

In this work we have studied the effect of a low-frequency alternating magnetic field (LF-AMF) on the permeability of magnetoliposomes, i.e. liposomes including magnetic nanoparticles within their water pool. Large unilamellar liposomes loaded with magnetic cobalt ferrite nanoparticles (CoFe2O4) have been prepared and characterized. Structural characterization of the liposomal dispersion has been performed by dynamic light scattering (DLS). The enhancement of liposome permeability upon exposure to LF-AMF has been measured as the self-quenching decrease of a fluorescent hydrophilic molecule (carboxyfluorescein, CF) entrapped in the liposome pool. Liposome leakage has been monitored as a function of field frequency, time of exposure and concentration, charge and size of the embedded nanoparticles. The results show that CF release from magnetoliposomes is strongly promoted by LF-AMF, reasonably as a consequence of nanoparticle motions in the liposome pool at the applied frequency. CF release as a function of time in magnetoliposomes unexposed to magnetic field follows Fickian diffusion, while samples exposed to LF-AMF show zero-order kinetics, consistently with an anomalous transport, due to an alteration of the bilayer permeability. These preliminary results open up new perspectives in the use of these systems as carriers in targeted and controlled release of drugs.
Analysis of the Material and Tablet Formation Properties of four Dioscorea Starches

The material and tablet formation properties of starches from four different Dioscorea species, namely White (D. rotundata), Bitter (D. dumetorum), Chinese (D. oppositifolia) and Water yam (D. alata), was characterized to determine their applicability as direct compression excipient. The physicochemical, thermal, morphological and material properties of the starches were investigated. The tablet formation properties were assessed using the 3-D modeling parameters, the Heckel equation and the force-displacement profiles. The tablet properties were evaluated using the elastic recovery and compactibility plots. The results indicate that the chemical composition, thermal and material properties of the starches varied considerably among the four species. The sorption isotherms show that the relative humidity (RH) during tablet production and storage should be carefully controlled. The tableting results show that all four starches exhibit similar time dependent deformation (d). The ranking for pressure plasticity (e) was Water > Chinese > White > Bitter, which indicates that Water deforms more easily and Bitter less easily. The ranking for fast elastic decompression was White > Water ≥ Chinese > Bitter. The amylose content, size and shape of the starch granules and specific surface area appears to play a significant role in the compressibility. Thus, White and Water with larger granules and high amylose content exhibited poor compressibility and did not form compacts except at high Prel,max, while Bitter and Chinese with polygonal shape, small particle size and high specific surface area were more compressible and formed tablets of acceptable crushing force. Thus, Chinese and Bitter could be useful as excipient in direct compression.
The calculation of correlation functions in fluids by a weighted density concept

An exact equation for the pair correlation function of fluids is derived by density functional methods. Comparing this result with the hypernetted chain (HNC) equation we propose a weighted density approximation for the so-called bridge function that improves the ordinary HNC theory. For a hard sphere fluid this method leads to thermodynamically more consistent results than the HNC, Percus-Yevick (PY) and Rogers-Young (RY) approximations. Adding an attractive potential to the hard sphere repulsion we obtain better correlation functions than can be found with the HNC and the reference HNC (RHNC) approximation.
Folding Free Energy Surface of a Three-Stranded β-Sheet Protein

We present a molecular dynamics (MD) simulation study of the folding thermodynamics of the three-stranded β-sheet protein Betanova. The protein and solvent are explicitly described by employing all atom models. An umbrella sampling technique was employed to probe thermodynamically relevant states at different stages of folding. A database for the sampling was generated by conducting four high-temperature simulations. The initial conditions for the umbrella sampling were selected from this database of structures by employing hierarchical clustering. Sampling of conformational space was then carried out at 275 K and the generated data were combined with the weighted histogram method to produce the two-dimensional folding free energy landscape. We found that the folding of the protein Betanova occurs in two collapse stages. The first collapse brings the protein into a basin that contains various structures differing in their size and elements of secondary structure. At the transition state from this basin of.
Preparation, characterization and electrical conductivity of doped polyaniline with (HCL and P-TSA)

Polyaniline (PANI) in Emeraldine salt form was prepared by chemical oxidative polymerization of the appropriate monomeric aniline using two different acid doping (Hydrochloric acid (HCL) and P-Toluene sulfonic Acid (PTSA)) respectively. The prepared samples were characterized by Fourier transform-infrared (FT-IR) spectroscopy; Ultraviolet- Visible (UV-VIS) spectroscopy and X-ray diffraction technique (XRD). The FT-IR and UV-VIS spectroscopy results indicate the doping state of PANi (HCL and PTSA). The crystallinity of the samples was studied in detail by X-ray diffraction technique. The (I-V) characteristic of (PANI) at room temperature, it was showed linear curve close to zero bias indicates that the charge transfer is a straight forward consequence of ohmic behavior, indicating that the measurement was performed in a field independent conductivity region. The scanning electron microscopy (SEM) was used to determine the morphology of the as-prepared nanomaterials
Microbial Transformations of Selenium and the Bioremediation of Seleniferous Environments

Selenium (Se) exists in many natural soil and water environments around the world, but anthropological activities such as irrigated agriculture on Se-laden soils has created many ecological problems with respect to this element. Seleniferous agricultural drainage water in California's San Joaquin Valley has been linked to the death and deformity of waterfowl. In the environment, microbial reduction, oxidation, methylation, and demethylation reactions predominantly control the oxidation state of Se and its subsequent behavior. In an effort to remediate these Se-contaminated environments a number of biological technologies have been investigated. Biological transformations of toxic Se oxyanions into less toxic or biologically unavailable forms, such as elemental Se or volatile Se compounds, has received much attention over the last decade. In this literature review, a major emphasis is placed on Se reduction and methylation/volatilization reactions because these processes are currently the most promising te.
Permanganate formation in the reactions of ozone with Mn(II): a mechanistic study

Ozone treatment of Mn2 + -containing waters is reported to lead to MnO4− formation. This complex reaction is investigated on the model level. In neutral solution, the main product is MnO2 and only 10% MnO4− are formed even at high ozone excess. In acid solution, however, or in neutral solution when Mn2 + is complexed by polyphosphate, oxalate, sulfate, bicarbonate or phosphate, the reaction proceeds to MnO4− in an up to 100% yield. In this reaction, three-times more O3 is consumed than stoichiometrically required indicating that higher manganese oxidations states can also be reduced by O3 (e.g., MnO2 + + O3→Mn2 + + 2O2). In acid solution or in the presence of a complexing agent and with Mn(II) in excess, Mn(III) is formed by conproportionation of Mn(II) with Mn(IV). Mn2 + -containing waters are accompanied by Fe2 + that also induces MnO4− formation. Fe2 + reacts 650-times faster with O3 than Mn2 + , and the oxidation of Mn2 + by Fe(IV) to Mn(III) can circumvent MnO2 formation. Mn(III) can then be oxidized to MnO4−. The thermodynamics of the suggested reactions is discussed. The MnO4− formation in drinking water and wastewater is most likely due to the presence of Fe2 + in these waters rather than due to complexation of Mn2 + by NOM or inorganics.
Photodegradation of Metolachlor in Water in the Presence of Soil Mineral and Organic Constituents

Photodegradation of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 253.7 nm was carried out in water containing soil minerals (kaolinite, montmorillonite, and goethite) and fulvic acid under two different pH conditions. The rate of photolysis was dependent on the nature of the soil constituents and the initial pH of the medium. Based on the regression analysis, it was shown that the photodegradation followed the first-order kinetics with respect to the metolachlor concentration, and the half-life of the herbicide under UV irradiation was longer in the absence of soil constituents. Hydroxylation, dehalogenation, oxoquinoline formation, and demethylation were the main processes observed during the photolysis of metolachlor. More degradation products were formed in the presence of kaolinite, montmorillonite, and goethite than with fulvic acid and water alone. The major degradation product formed under UV irradiation in all the treatments was identified as 4-(2-ethyl.
Extractive composition and summative chemical analysis of thermally treated eucalypt wood

Abstract Eucalypt wood (Eucalyptus globulus) was heated in an oven for 2–24 h at 170–200°C and in an autoclave with superheated and saturated steam for 2–12 h at 190–210°C. The chemical composition of untreated wood and thermally treated wood with different mass losses in the range of 1.1–11.9% was studied by summative analysis, and the composition of dichloromethane, ethanol and water extracts was determined by gas chromatography mass spectometry (GC-MS). The hemicelluloses degraded first, mainly regarding the arabinose and xylose moieties. Lignin degraded at a slower rate and cellulose was only slightly affected under severe treatment conditions. The extractive content increased first with heat treatment and decreased later on. Almost all of the original extractives disappeared and new compounds were formed, such as anhydrosugars, mannosan, galactosan, levoglucosan and two C5 anhydrosugars. The most prominent lignin derived compounds were syringaldehyde, syringic acid and sinapaldehyde. The main difference between autoclave and oven treated samples was the appearance of more oxidized extractives for the oven treatment.
13N-nitrate uptake sites and rhizobium-infectible region in a single root of common bean and soybean

Abstract The positron emitting tracer-imaging system (PETIS) was used to determine whether it was possible to obtain on image of 13N-distribution in common bean in which a single root was fed with a liquid medium containing nitrate at different concentrations with different 13N specific activities. The distribution of the images of the 13N atoms in the root could be obtained over a wide range of nitrate concentrations and 13N specific activities in the medium. As for nitrate stress on leguminous root nodulation, the positional relationship between the nitrate uptake sites and root hair just elongating area, where rhizobia capably initiate their infection, was studied in common bean and soybean. PETIS gave direct evidence that single roots of both common bean and soybean showed one or two dense 13N-distribution areas after 2 min pulse-feeding of 13N03 -. These areas remained stable over 30 min, and the first dense site, which was common in all the examined roots, extended over ca. 1 cm above the root apex.
Arc Plasma Synthesis of (Fe-Nd-B) - Containing Carbon Encapsulates

The formation of novel carbon nanostructures containing Fe-Nd-B nanocrystallites is reported. Tests were performed in a DC arc plasma reactor under He atmosphere using (Fe-Nd-B)- filled anodes. The influence of the operational parameters pressure and anode composition on the product morphology was studied. The products were analyzed by HR TEM, MFM and magnetic measurements. Emission spectroscopy was performed to determine the temperature and C2 radical distribution in the arc.
Electron attachment to carbon dioxide clusters in a supersonic beam

Negative ions have been observed in a time‐of‐flight man spectrometer with charge‐to‐man satios corresponding to (CO2)−n with 2⩽n⩽6. It is concluded that these ions are formed by electron attachment to clusters formed in the rapidly expanding CO2 beam from a sonic nozzle. (AIP)
Synthesis, Self-Assembly, and Magnetic Properties of Fe x Co y Pt 100- x - y Nanoparticles

FexCoyPt100-x-y alloy nanoparticles were prepared by the simultaneous reduction of cobalt acetylacetonate and platinum acetylacetonate and the thermal decomposition of iron pentacarbonyl. The relative amounts of iron, cobalt, and platinum in the particles depended on the amount of iron, cobalt and platinum charged to the reaction. As prepared, the particles were superparamagnetic and had a distorted fcc structure. The average particle diameter was 3.5 nm and the size distribution was very narrow. The particles could be dispersed in hydrocarbon solvents and formed films consisting of hexagonal close-packed particles on carbon-coated copper TEM grids. The films were sputter coated with amorphous carbon and then annealed at temperatures ranging from 550 to 700 °C to transform the particles to the tetragonal (L10) phase. The coercivity of the annealed films increased with increasing annealing temperature. For films with a similar degree of transformation to the tetragonal phase, increasing the cobalt content .
Amine-linker length dependent electron transfer between porphyrins and covalent amino-modified single-walled carbon nanotubes

Single-walled carbon nanotube (SWNT)-porphyrin hybrid materials have received much attention due to their promising applications in photovoltaic devices, photodynamic therapy and energy conversion. Herein, three covalent amine-modified single-walled carbon nanotubes with different alkyl chain lengths have been synthesized and characterized by FT-IR, 1H NMR, XPS, and TGA-DTA methods. The electron transfer (ET) between SWNTs and porphyrins has been studied and the important influencing ET factors, such as linker length, solvent polarity, pH and ionic strength, and central metal of porphyrin, are discussed in detail in this report. Our results indicate that shorter alkyl chain length, higher polarity of the solvent, lower pH and ionic strength are all favorable for ET, the central metal coordinated to the porphyrin macrocycle is not essential for ET.
Searching for Vanadium-Based Prospective Agents against Trypanosoma cruzi: Oxidovanadium(IV) Compounds with Phenanthroline Derivatives as Ligands†

Searching for new promising metal-based drugs for the treatment of parasitic diseases against Trypanosoma cruzi, three related oxidovanadium(IV) complexes, [VIVO(SO4)(H2O)2(NN)], with the phenanthroline derivatives (NN) 1,2,5thiadiazolo[3,4-f]1,10phenanthroline (tdzp), 1,10-phenanthroline-5, 6-dione (phendione), and 5,6-epoxy-5,6-dihydro-1,10-phenanthroline (epoxyphen) are synthesized, characterized, and evaluated in vitro as anti-T. cruzi agents. The compounds are characterized in the solid state and in solution by elemental analysis, electrospray ionization mass spectrometry (ESI-MS), conductimetric measurements, and infrared (FTIR), UV/Vis, and electronic paramagnetic resonance (EPR) spectroscopy. EPR spectroscopy suggests that the ligands act as bidentate, binding through both nitrogen donor atoms in an axial-equatorial mode. DFT calculations corroborate the structural assignments. The stability of the complexes in solution is evaluated by EPR and 51V- NMR spectroscopy and all complexes show reasonable stability. The anti-T. cruzi activity of the complexes was tested by measuring the growth inhibitory effect on the epimastigote life cycle form of the parasite (Dm28c strain). All complexes show IC50 values in the micromolar range against T. cruzi and display activities of the same order of that of Nifurtimox, but lower than that of the previously reported analogue [VIVO(SO4)(H2O)2(dppz)] (dppz = dipyrido[3, 2-a:2′,3′-c]phenazine). Furthermore, DNA was evaluated as a potential target by using atomic force microscopy (AFM), showing that the complexes display ability to interact with this biomolecule.
Des Moines River Nitrate in Relation to Watershed Agricultural Practices: 1945 Versus 1980s

Concern for nitrate (NO 3 -N) contamination of surface waters in Iowa has brought much speculation with regard to the source of NO 3 -N. It is frequently assumed that the large percentage increase in fertilizer N use over the last 50 yr is the primary cause of high concentrations of NO 3 -N in surface waters of central Iowa. We performed an analysis of data relating flow and NO 3 -N concentration for the Des Moines River to identify the effect of agricultural practices on NO 3 -N in the river.
Physico-Chemical Differences Between Particle-and Molecule-Derived Toxicity : Can We Make Inherently Safe Nanoparticles?

The rapidly growing applications of nanotechnology require a detailed understanding of benefits and risks, particularly in toxicology. The present study reviews the physical and chemical differences between particles and molecules when interacting with living organisms. In contrast to classical chemicals, the mobility of nanoparticles is governed by agglomeration, a clustering process that changes the characteristic size of the nanomaterials during exposure, toxicity tests or in the environment. The current status of nanotoxicology highlights non-classical toxic interactions through catalytic processes inside living cells and the enhanced heavy metal transport into the cytosol through the 'Trojan horse mechanism'. The safety of nanoparticles in consumer goods is proposed to be rendered inherently safer by substituting the currently used persistent oxides through biodegradable materials.
A New Method for Generating Minimal Perfect Hash Functions

A perfect hash function, PHF, is an injection, F, from a set, W, of M objects into the set consisting of the first N non-negative integers where N>=M. If N=M then F is a minimal perfect hash function, MPHF. PHFs are useful for the compact storage and fast retrieval of frequently used objects such as reserved words in a programming language or commonly employed words in a natural language. The mincycle algorithm for finding PHFs executes with an expected time complexity proportional to and has been used successfully on sets of cardinality up to 256. The mincycle algorithm first chooses three pseudo-random functions h0,h1 and h2 , then chooses an appropriate ordering of W, and finally performs an exhaustive search for a function, g, which makes F(w) = (h0(w) + g ∙h1 (w) + g ∙h2(w)) mod N a PHF. The chosen ordering is used to reduce the time necessary to perform the exhaustive search.
Comment on “Mechanisms of the multi-shape memory effect and temperature memory effect in shape memory polymers” by L. Sun and W. M. Huang, Soft Matter, 2010, 6, 4403

Li Sun et al. showed that the temperature corresponding to the maximum recovery stress in constrained recovery was roughly the temperature at which pre-deformation, also known as the temperature memory effect (TME), occurred in shape memory polymers (SMPs). A theoretical framework was presented to investigate the underlying mechanisms for the TME. Here, we show that the scope of this report remains limited to the theoretical framework. In this comment, a phenomenological model is proposed to quantitatively separate the effect of stored mechanical energy on the TME in SMPs, in combination with the relaxation theory and the experimental work of Pierre Miaudet et al.
Short-time dynamics of glass-forming liquids: Phenyl salicylate (salol) in bulk liquid, dilute solution, and confining geometries

Raman spectroscopy has been used to investigate picosecond vibrational dynamics of the molecular glass-former phenyl salicylate (salol). The study has concentrated on the elucidation and comparison of molecular dynamics of salol subjected to different local environments, namely in bulk, in a dilute CCl4 solution, and under spatial confinement in nanoporous sol–gel glasses. Contrary to most of the previous picosecond dynamics studies performed by means of Raman line profile analysis, we have employed in this paper a novel approach that enables the extraction of valuable short-time dynamics information through spectra fitting in the frequency domain. As a result, strongly overlapping vibrational lines can be put in focus. The analysis has shown a systematic dependence of vibrational relaxation on the local environment around a salol molecule. The magnitude of the vibrational relaxation time τV decreases in the sequence dilute solution→bulk liquid→confined liquid, indicating the modification of interactions .