Miracle-dz/UniFAR-FTUs huggingface dataset:
Novel hydrophilic chitosan‐polyethylene oxide nanoparticles as protein carriers

Hydrophilic nanoparticulate carriers have important potential applications for the administration of therapeutic molecules. The recently developed hydrophobic-hydrophilic carriers require the use of organic solvents for their preparation and have a limited protein-loading capacity. To address these limitations a new approach for the preparation of nanoparticles made solely of hydrophilic polymers is presented. The preparation technique, based on an ionic gelation process, is extremely mild and involves the mixture of two aqueous phases at room temperature. One phase contains the polysaccharide chitosan (CS) and a diblock copolymer of ethylene oxide and propylene oxide (PEO-PPO) and, the other, contains the polyanion sodium tripolyphosphate (TPP). Size (200–1000 nm) and zeta potential (between +20 mV and +60 mV) of nanoparticles can be conveniently modulated by varying the ratio CS/PEO-PPO. Furthermore, using bovine serum albumin (BSA) as a model protein it was shown that these new nanoparticles have a great protein loading capacity (entrapment efficiency up to 80% of the protein) and provide a continuous release of the entrapped protein for up to 1 week. © 1997 John Wiley & Sons, Inc.
Comparison of Nitrided HfO2 Films Deposited in O2 and N2O by Direct Liquid Injection CVD

Nitrided HfO 2 films are deposited by direct liquid injection chemical vapor deposition (CVD) using O 2 or N 2 O as oxidants. Deposition kinetics, phase, chemical composition, bonding, and dielectric properties of the films obtained from the two different oxidants are compared. Depositions in nitrous oxide display an activation energy (9.9 kcal/mol) less than that observed with oxygen (13.6 kcal). Films obtained from nitrous oxide are amorphous as determined by grazing incidence X-ray diffraction, while films deposited using oxygen are mixtures of amorphous and crystalline phases. Films deposited from nitrous oxide have lower bulk and interface (with silicon) nitrogen concentrations relative to films deposited in oxygen. The amorphous structure of nitrous oxide deposited films and an enhanced concentration of oxygen atoms from nitrous oxide are believed to be the reasons for the reduced interface nitrogen concentrations. Capacitance-voltage measurements demonstrate that films deposited with nitrous oxide have lower dielectric constants and lower interface trap densities relative to films deposited from oxygen. Leakage currents of the films deposited in nitrous oxide are smaller than those of films deposited in oxygen. Nitrogen concentration and oxygen content at the film/silicon substrate interface appear to be the reason for the distinct electrical properties of films deposited using the two oxidants.
Very small bubbles at surfaces—the nanobubble puzzle

Atomic Force Microscope images and other experiments show us that very small stable bubbles, known as nanobubbles, can be present on surfaces despite well founded theoretical considerations that predict otherwise. Nanobubbles are thought to play a role in the rupture of thin films during froth flotation, hydrodynamic slip over surfaces, interaction forces between hydrophobic surfaces and influence the electroplating and electrolysis processes. Here we describe what is known of nanobubbles and discuss the challenges in understanding nanobubble morphology and stability.
Metal binding with root exudates of low molecular weight

SUMMARY Root exudates were collected from maize plants (Zea mays L.), grown under sterile and hydroponic conditions. Exudates of low molecular weight were isolated by filtration and dialysis (MW 1000) of the nutrient solution and analysed. Metal binding properties of the exudates were investigated at 25°C in 0.1 m NaCIO4 ionic medium, using a potentiometric method. The total acidity of the exudates and the successive stability constants of complexes formed with Cu2+, Pb2+ and Zn2+ were determined. Sugars and organic acids were the major components of the exudates. Measured total acidity was resolved into strong (5.85meq g−1C), weak (2.10meq g−1C) and very weak (2.20 meq g−1 C) acidities. Mono-complexes were formed with Cu, Pb and Zn and bis-complexes with Cu. At pH 5, stability constants followed the order Cu>Pb>Zn.
Nanoassembly of immobilized ligninolytic enzymes for biocatalysis, bioremediation, and biosensing

Extracellular enzymes, lignin peroxidase (LiP) and manganese peroxidase (MnP) from white rot fungus Phanerochaete chrysosoporium, have been shown to degrade various harmful organic compounds ranging from chlorinated compounds to polycyclic aromatic hydrocarbons (PAH) to polymeric dyes. The problems in using immobilized enzymes for biocatalysis/bioremediation are their loss of activity and long-term stability. To address these issues, adsorption by layer-by-layer assembly (LbL) using polyelectrolytes, entrapment using gelatin, and chmisorption using coupling reagents have been investigated. In order to increase surface area for catalysis, porous silicon, formed by electrochemical etching of silicon, has been considered. The efficacy of these extremely stable nanoassemblies towards degradation of model organic compounds-veratryl alcohol (VA and 2,6-dimethoxyphenol (DMP)-in aqueous and in a mixture of aqueous/acetone has already been demonstrated. In parallel, we are pursuing development of sensors using these immobilized enzymes. Experiments carried out in solution show that NO can reversibly bind Ferri-LiP to produce a diamagnetic complex with a distinct change in its optical spectrum. NO can be photolyzed off to produce the spectrum of native paramagnetic ferri-species. Preliminary data on the detection of NO by LiP, based on surface plasmon resonance (SPR) using fiber optic probe, are presented.
Search for the most stable folds of protein chains: II. Computation of stable architectures of P-proteins using a self-consistent molecular field theory

In a preceding paper we presented a novel approach to computation of 3-D folds of protein chains from their amino acid sequences. This approach is a physically correct generalization of the 'threading' methods. It is based on a self-consistent molecular field theory and on a physical theory of protein folding patterns, which make it possible to examine all the variety of 'potentially stable' folding patterns and all the variety of the chain conformations within each of them and to determine the thermodynamically stable structure. In this paper, we apply this approach to single out stable folding patterns and conformations for the chains of ({-sandwich proteins and show that the similarity of the calculated and observed structures is usually rather close.
Halocarbons in Antarctic surface waters and snow

Abstract Surface and pit snow samples, collected from Terranova Bay area in Antarctica during the Italian expeditions of 1991–92 and 1992–93, were analysed, for halocarbons, namely tetrachloromethane, trichloroethylene and tetrachloroethylene. The results obtained (including those related with lake and ice water samples previously reported) were evaluated with respect to the worldwide distribution of these compounds and their diffusion to a global scale. Important innovations concerning sensitivity and reproducibility of the analytical method, are also reported.
Carcinogenicity of Coal Tars: A Multidisciplinary Approach

Abstract Coal tars, which are byproducts of coal gasification, are complex mixtures of chemicals including polycyclic aromatic hydrocarbons. Occupational exposure to coal tars is associated with a higher risk of cancer. The risk posed by environmental coal tars, and related oil tars, which may involve prolonged exposures to low doses, is not known. While this risk may be inferred from a knowledge of the concentration and potency of known carcinogenic components, the complexity and incomplete chemical analysis of coal tars lead to estimates with large uncertainties. In order to assess risk with greater certainty, laboratory studies were conducted to evaluate cancer induction following oral administration of coal tars. The appropriateness of these animal data to humans was evaluated in studies of the effects of these tars on genotoxicity, metabolism and gene expression. Our data suggest that the potency of coal tars cannot be predicted accurately from an understanding of the biological or carcinogenic effec.
Photochemical Degradation of Dimethyl Phthalate by Fe(III)/tartrate/H 2 O 2 System

Photochemical degradation of dimethyl phthalate (DMP) in Fe(III)/tartrate/ system was investigated utilizing fluorescent lamps as the primary light source. Effects of initial pH, light source, and initial concentration of each reactant on DMP photodegradation was examined. The results show that the system was able to effectively photodegrade DMP utilizing visible light. Fluorescent lamp, halide lamp, UV lamp and sunlight could all be used as the light sources. The optimal pH ranged among 3.0-4.0 for the system. Increases of the initial concentrations of Fe(III) and accelerated the photodegradation of DMP, whereas excessively high initial tartrate concentration resulted in the decrease of photodegradation efficiency and rate of DMP.
Analysis of multi-configuration density functional theory methods: theory and model application to bond-breaking

We consider the extension of the standard single-determinant Kohn–Sham method to the case of a multi-configuration auxiliary wave function. By applying the rigorous Kohn–Sham method to this case, we construct the proper interacting and auxiliary energy functionals. Following the Hohenberg–Kohn theorem for both energy functionals, we derive the corresponding multi-configuration Kohn–Sham equations, based on a local effective potential. At the end of the analysis we show that, at the ground state, the auxiliary wavefunction must collapse into a single-determinant wave function, equal to the regular KS wavefunction. We also discuss the stability of the wavefunction in multi-configuration density functional theory methods where the auxiliary system is partially interacting, and the remaining (residual) correlation is evaluated as a functional of the density. As an example showing both the challenges and the possibilities, we implement such a procedure for the perfect pairing wavefunction, using a residual correlation functional that is based on the Lee–Yang–Parr functional, and present results for an elementary bond-breaking process.
Charge transfer and tree initiation in polyethylene subjected to AC voltage stress

An electrical tree is grown in the region of a dielectric subjected to an intensified local electric field. It can be artificially generated in a specimen by using a needle-to-plane electrode configuration. It is characterized by an incubation period which usually tends to decrease with applied voltage. During this period, charge carriers (electrons and positive holes) move back and forth repeatedly between the electrode and the dielectric. This repeated charge transfer is believed to be mainly responsible for tree initiation. Two main contributions can be conceived: the space charge buildup and the attack on the polymer chains by high-energy charge carriers. A space-charge distortion model is proposed for the initiation of an electric tree in polyethylene. This model can also include material aging processes initiated by injected carriers. It can explain ultraviolet light emission and morphological effects which are experimentally observed in association with tree initiation. >
Analysis of Lithium Insertion/Deinsertion in a Silicon Electrode Particle at Room Temperature

The dependence of the open-circuit potential on the state of charge in lithium insertion electrodes is usually measured at equilibrium conditions. For the modeling of lithium-silicon electrodes at room temperature, the use of a pseudo-thermodynamic potential vs composition curve based on metastable amorphous phase transitions with path dependence is proposed. Volume changes during lithium insertion/deinsertion in a single silicon electrode particle under potentiodynamic control are modeled and compared with experiments to provide justification for the same. Only if asymmetric transfer coefficients and sluggish kinetics are experimentally observed can kinetic hysteresis be reasoned for the potential gap in Li-Si system. The particle model enables one to analyze the influence of diffusion in the solid phase, particle size, and kinetic parameters without interference from other components in a practical porous electrode. Concentration profiles within the electrode particle under galvanostatic control are investigated. Sluggish kinetics is established from cyclic voltammograms at different scan rates. This work stresses the need for accurate experimental determination of kinetic parameters (and thus the exchange current density) in silicon nanoparticles. This model and knowledge thereof can be used in the cell-sandwich model for the design of lithium-ion cells with composite silicon negative electrodes.
A new version of AgFON substrates for high-throughput analytical SERS applications

The drop coating technique was applied to generate thin films of various polymer nanospheres as a basis for the preparation of AgFON (Ag films over nanospheres). In contrast to the well known spin coating technique, the chosen procedure also allows the use of multiwell (microtiter) plates as substrate, thereby opening up the possibility of a high-throughput analysis technique based on SERS. Employing commercially available spheres of polystyrene (diameter 533 nm) or silica (diameter 470 nm) and an Ag top layer 200 nm thick, SERS spectra of several food dyes were recorded; for Brillant Green (E 142), the detection limit was about 500 pg per well. Copyright © 2002 John Wiley & Sons, Ltd.
The Observation of the Combustion Initiated by a Free Ele ctrons Cloud

*† The paper describes the results of the electron -beam ini tiation of the combustion in the mixtures of hydrogen, natural gas and kerosene vapors with air, graphite microparticles suspe nsion in oxygen. The means of controlling these reactions with the aid of the electron beam are shown. The graphite combustion ini tiation occurred at the moment of the beam start, for the homogeneous mixtures the ignition delay reached several hundreds microse conds. Combu stion initiation in the stream of oxygen – natural gas mixture at M=5 was obtained.
Functional Diversity and Size of Soil Microbial Communities Induced by Different Land Management Systems

Abstract Soil microorganisms drive nutrients cycling to a great extent, and they play an essential role in maintaining a stable soil ecosystem and ensuring sustainable forestry development. Land management has been proven to be a real factor in influencing soil quality. The purpose of this study was to investigate the effects of different land management techniques on soil microbial communities. There were four types of land management systems selected for this study: natural masson pine, Phyllostachy pubescens, Phyllostachys praecox, and vegetable. Soils were sampled from these four systems and assayed for soil microbial biomass carbon (MBC), community level substrate utilization pattern, functional diversity, and principle component analysis. Values of MBC were significantly different (P<0.05) from one another in the order of masson pine>Phyllostachy pubescens>Phyllostachys Praecox>vegetable. Analysis of community level substrate utilization pattern indicated that carbon source utilization and total activity by soil microorganisms were greater under the masson pine system than the other three systems (P<0.01). The functional diversities of soil microbial communities characterized as Shannon and McIntosh indexes were much richer in soil under masson pine system; Shannon index was 4.483, 4.241, 4.224, and 3.938 and McIntosh index was 13.51, 7.332, 6.272, and 6.261 for natural masson pine, Phyllostachy pubescens. Phyllostachys praecox, and vegetable systems, respectively. The results from the principle components analysis (PCA), based on the data of optical density (OD) at 120 h of incubation, showed that the value of the first principal component (PC1) of soil for natural masson pine was greater (P<0.05) than those for the other three systems. The difference in scores of the second principal component (PC2) between Phyllostachy pubescens, Phyllostachys praecox, and vegetable were not statistically different. The size and activity of soil microbial communities generally decreased with soil depth, with significant differences in soil MBC, community level substrate utilization pattern, and functional diversity indexes found between A and C horizons (P<0.01). It was concluded that land management systems had a great influence on soil microbial biomass, activity, and functional diversity.
Benzo(a)pyrene air concentrations and emission inventory in Lombardy region, Italy

Three years of particle phase B(a)P air concentration measurements in 13 sites in Lombardy (Italy) and a detailed emission inventory at the municipal scale for the whole region were used to infer the contribution of different sources to B(a)P atmospheric levels. The analyses of the weekly and monthly profiles of B(a)P concentrations, the cluster analysis and the comparison between the B(a)P/PM10 ratios in ambient air and in the emissions allowed identifying wood burning in small residential appliances as the key source for all the sites, except for those located in Milan. The highest values of the average B(a)P concentrations were not found in the wider urban areas, where in general the highest PM10 levels were registered. Regarding the seasonal variability, a marked reduction of both B(a)P concentrations and B(a)P/PM10 ratios was observed in the summer season. The cluster analysis of PM10 and B(a)P concentrations showed that the two pollutants tend to have a separate pattern; moreover the cluster analysis of B(a)P/PM10 ratios showed that the trend of this ratio split the stations depending on their location: plain area, piedmont and valley zones, and mountain sites. The dominance of the wood combustion highlighted by the emission inventory, originating from the residential sector and from pizzerias in the city of Milan, is consistent with the findings of other studies based on a source apportionment approach or air quality modeling, although some patterns of ambient B(a)P concentrations in one site were not adequately explained by the emission sources included in the emission inventory.
Electron and metastable kinetics in the nitrogen afterglow

This work presents a theoretical study of the time-relaxation of both the electron energy distribution function and the populations of the different species of interest in the nitrogen afterglow of a ω/2π = 433 MHz discharge at p = 3.3 Torr, in a tube with radius R = 1.9 cm. It is shown that collisions of highly excited N2(X 1 � + g ,v 35) molecules with N( 4 S) atoms may be in the origin of the observed pronounced maxima for the concentrations of various species, including electrons, occurring downstream from the discharge after a dark zone. Slow electrons remain for very long times in the post-discharge (at least up to t ∼ 10 −3 –10 −2 s), and the strong coupling between the electron and metastable kinetics is clearly pointed out.
Crosslinking kinetics of thermally preset alginate gels

The Sharp-Interface model was used to describe the crosslinking kinetics of thermally preset calcium alginate gel at constant temperature. The model assumes diffusion of calcium ions through a preformed gel of sodium alginate and a selected carrier, and an instantaneous reaction between the calcium and sodium alginate. The proposed model was experimentally verified using two different carriers at the following concentrations: agar 0.6(g/100 mL)-0.8(g/100 mL), and gelatine 4(g/100 mL); sodium alginate concentrations were 1(g/100 mL) and 1.5(g/100 mL), while a 2(g/100 mL) calcium lactate solution was used as calcium ion source. The diffusion coefficient of calcium ion was determined using a cell diffusion model. The model can be used to predict processing effects on food gels.
Organically Functionalized Mesoporous Silica by Co‐structure‐Directing Route

This article provides a brief overview of functional mesoporous silica materials synthesized by the co‐structure‐directing route, which is distinct from conventional synthesis strategies. In these systems, organosilane serves as the co‐structure‐directing agent (CSDA), which provides critical interactions between the template and organic part of the organosilane to form mesostructures, thus retaining the organic groups on the pore surface after removal of the template by extraction. i) The formation of anionic‐surfactant‐templated mesoporous silicas (AMSs) has been achieved by the co‐structure‐directing route, which leads to a variety of mesostructures, porous properties and morphologies. ii) Other co‐structure‐directing systems for synthesizing mesoporous silicas have also been achieved, including systems using cationic surfactants and non‐surfactants, and systems using DNA for constructing nanofibers and DNA–silica liquid crystalline complexes. iii) Evidence for the regular arrangement of functional groups on the pore surface resulted from the co‐structure‐directing effect has been discussed. Also included is a brief description of the application, future requirements, and trends in the development of mesoporous materials by the co‐structure‐directing route.
Formation and Aging of Precipitates. VIII. Formation of Monodisperse Particles (1) Gold Sol Particles by Sodium Citrate Method

Gold sol particles prepared by sodium citrate method were monodisperse. The size of gold particles decreased exponentially with increasing initial concentration of the auric ion, and increased exponentially with the reaction temperature. At the initial stage of the reaction of the gold sol formation, the gold nuclei were formed rapidly. After the nucleation the number of particles was kept constant over the whole period of reaction and the particles grew with the autocatalysis-like reaction at the surface of the particle.
Influence of surfactant assembly on the formation of calcium phosphate materials—A model for dental enamel formation

Novel calcium phosphate materials were synthesized from solutions containing the surfactant bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT), water and oil. A range of morphologies was obtained by varying the relative concentrations of the solution components. A material with structural features resembling tooth enamel was produced from a highly viscous reaction solution. This material consisted of bundles of co-aligned filaments, 750 nm–1 µm in length and 250–350 nm wide. Each bundle contained 10–20 filaments, identified as hydroxyapatite crystals. Electron diffraction of the bundles resulted in an arc pattern indicative of elongated aligned crystals, and similar to that known for dental enamel. Systems such as this may be used as models to gain insight into the mechanisms involved in the biomineralization of tooth enamel. Importantly, we have provided new evidence in support of the hypothesis that hierarchical structures in nature result from cooperative interactions between organic assembly and crystal growth. Amorphous calcium phosphate nanoparticles, hollow spheres, spherical octacalcium phosphate aggregates of plates and elongated plates of calcium hydrogen phosphate dihydrate were also obtained under different sets of conditions that altered AOT assembly and solution viscosity. These latter findings illustrate further the significant influence of organic assembly on the formation of calcium phosphate materials.