Miracle-dz/UniFAR-FTUs huggingface dataset:
Mechanism of CO3- substitution in carbonate-fluorapatite: Evidence from FTIR spectroscopV, t3C NM& and quantum mechanical calculations

The substitution of COI in carbonate-fluorapatite ("francolite") has a destabilizing effect on the apatite structure that results in increased solubility. A commonly proposed substitution mechanism involves the replacement of a POI ion by CO3F3-, in which C is at the center ofa tetrahedron and is surrounded by three O atoms and one F atom at the corners. However, no spectroscopic evidence exists for this hypothetical anion. We have investigated the microenvironment of CO! in '3C-enriched type B synthetic and natural sedimentary carbonate-fluorapatite samples by '3C static and MAS NMR and FTIR spectroscopies. (True COIsubstitution in the apatite structure was ascertained by X-ray diffraction and FTIR.) The COIion itself consists of an sp'? -hybridized planar arrangement of three O atoms about the central C atom. If the CO3geometry were changed to an sp3 hybrid with F at one comer, the NMR chemical isotropic shift would change considerably, owing to the altered environment about the central C atom. Also, there would be an internuclear dipolar interaction between t3C and teF. Simulated NMR spectra for r3c-reF distances of 1.38 and 2.00 A based on the sp3 model are very different from those obtained on our apatite samples, which are instead characteristic of C in a planar sp2 arrangement and no r3c-reF dipolar coupling. No evidence for direct bonding between COIand F was found. This result is confirmed by abinitio quantum mechanical calculations, which show that the hypothetical COtF3ion is unstable in an apatitic environment. Ab-initio results, as well as FTIR data, favor the existence of an interstitial position for Fif nonstoichiometric amounts of this element are present rn apatrte.
Polymer-derived SiCN and SiOC ceramics – structure and energetics at the nanoscale

The complex nanodomain structure and energetic features of polymer-derived SiCN and SiOC ceramics have been investigated by multinuclear 1D and 2D solid-state NMR, micro-Raman, SAXS, XRD, HRTEM and oxidative high temperature oxide melt solution calorimetry, respectively. Structural models consistent with all these lines of evidence put emphasis on interconnected fractal domains stabilized by the mixed-bond-structure and interface bonding between nanodomains. The structural and thermodynamic role of hydrogen in the stabilization of interfacial bonding between the nanodomains in polysilylcarbodiimide-derived SiCN is reported as well.
Toxicology of ultrafine particles: in vivo studies

Ultrafine particles (less than 100 nm in diameter) are encountered in ambient air and at the workplace. Normal background levels in the urban atmosphere for ultrafine particles are in the range 1–4 × 104 cm−3; however, their mass concentration is normally not greater than 2 μg m−3. At the workplace, ultrafine particles occur regularly in metal fumes and polymer fumes, both of which can induce acute inflammatory responses in the lung upon inhalation. Although ultrafine particles occurring at the workplace are not representative, and, therefore, are not relevant for urban atmospheric particles, their use in toxicological studies can give valuable information on principles of the toxicity of ultrafine particles. Studies in rats using ultrafine polymer fumes of polytetrafluoroethylene (PTFE) (count median diameter ca. 18 nm) showed that (i) they induced very high pulmonary toxicity and lethality in rats after 15 min of inhalation at 50 μg m−3; (ii) ageing of PTFE fumes resulted in agglomeration to larger particles and loss of toxicity; (iii) repeated pre–exposure for very short periods protected against the toxic and lethal effects of a subsequent 15 min exposure; (iv) rapid translocation of PTFE particles occurred to epithelial, interstitial and endothelial sites. Since one characteristic of urban ultrafine particles is their carbonaceous nature, exposure of rats to laboratory–generated ultrafine carbonaceous (elemental, and organic, carbon) particles was carried out at a concentration of ca. 100 μg m−3 for 6 h. Modulating factors of responses were prior low–dose inhalation of endotoxin in order to mimic early respiratory tract infections, old age (22–month old rats versus 10–week old rats) and ozone co–exposure. Analysis of results showed that (i) ultrafine carbon particles can induce slight inflammatory responses; (ii) LPS priming and ozone co–exposure increase the responses to ultrafine carbon; (iii) the aged lung is at increased risk for ultrafine particle–induced oxidative stress. Other studies with ultrafine and fine TiO2 showed that the same mass dose of ultrafine particles has a significantly greater inflammatory potential than fine particles. The increased surface area of ultrafine particles is apparently a most important determinant for their greater biological activity. In addition, the propensity of ultrafine particles to translocate may result in systemic distribution to extrapulmonary tissues.
Control of surface reactions in high-performance SiO2 etching

The relation between SiO2 etch rates and incident fluxes of reactive species in a dual-frequency (27 MHz and 800 kHz) parallel-plate system was evaluated by using various in situ measurements tools. C4F8/Ar/O2 was used for etching gases. The steady-state thickness TC–F of a fluorocarbon polymer layer on the etched SiO2 surface was also measured. The SiO2 etch rate could be related to total F atom flux ΓF-total, which depends on both the incident fluxes of C–F reactive species and the surface reaction probability s. The s is a function of the net energy on the reactive layer (Vnet). This energy is determined by the incident ion energy and the energy loss at the C–F polymer on the etched surface. A change in Vnet from 500 to 1450 V was estimated to correspond to a change in s from 0.01 to 0.1. The steady-state thickness of the C–F polymer TC–F increased when excess C–F species were supplied to the etched surface. A thick polymer (TC–F>1 nm) decreases the ion energy and slows or stops the etching in fine hol.
The Barrier Effect of EVOH versus 1,4,7‐Triaxocyclotridecane‐8,13‐Dione, a Non‐intentionally Added Compound from Polyurethane Adhesives in Multilayer Food Packaging

The presence and migration of non‐intentionally added substances in food packaging materials are the big concerns nowadays in terms of food safety, and the identification and quantitation are an important analytical challenge. Among non‐intentionally added substances, 1,4,7‐trioxacyclotridecane‐8,13‐dione, a by‐product resulting from the interaction between ingredients in many polyurethane adhesives, has been identified and quantified.
Reduction of graphene oxide with substituted borohydrides

The emergence of graphene as a next-generation material promises enhanced improvement in various fields of materials science. So far, the oxidation of graphite to graphite oxide and consequent reduction to chemically reduced graphene oxide is the most relevant method towards large scale production of graphene materials. Our long-standing aim in the investigation of reductive chemical reactions on graphene surfaces is to evaluate standard, well documented organic synthetic reactions with well-known mechanisms. Sodium borohydride is one of the most common reductants to reduce graphene oxide to chemically reduced graphene oxide, and is only one of the very few with a well-known mechanism. It is well-known in synthetic chemistry that the reducing strength of borohydrides can be fine-tuned by alternating their substituents. This knowledge has not yet been applied to the reduction of graphene oxides. Herein, we expand on the scope for reduction of graphene oxides using various derivatives of borohydrides, specifically sodium cyanoborohydride and sodium triacetoxyborohydride, and investigate the extents of reduction conferred by these variations with comparison to sodium borohydride. The reduced graphenes were characterized by high resolution X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry analyses. Our findings highlighted that sodium triacetoxyborohydride is inclined to react unfavourably with graphene oxide, thus resulting in a graphene material with an almost similar electrochemical characteristic to its precursor. On the other hand, sodium cyanoborohydride conferred obvious reductive effects but was still less effective when compared to sodium borohydride. Our findings bring a deeper understanding of the effects of organo-boron substituents on the extent of graphene oxide reduction. This would allow for potential tailoring of the graphene properties for various applications.
Adsorption Profile and Complexing Behavior of Hg(II) Ions onto Polyurethane Foam from Acidic Mixed Solvent System (H2O + Ethanol) Containing Dithizone

A new method has been developed to remove Hg(II) metal ion by preconcentrating onto polyurethane foam (PUF) from acidic mixed solvent system (0.5 N HNO3 + 25% ethanol) containing dithizone. Batch experiments were carried out to assess adsorption equilibrium and kinetic behavior by varying parameters such as acid concentration, agitation time, aqueous- ethanol ratio, and metal ion concentration. These facilitated the computation of kinetic parameters and adsorption behavior. The optimum conditions of sorption of mixed solvent system are 0.5 mol L−1 HNO3 + 25% ethanol containing 1.95 × 10−4 mol L−1 of dithizone with 40 minutes of equilibrium time. The kinetic parameters indicate that sorption follows the first-order reaction and intraparticle diffusion process. The obtained data followed the adsorption models. i.e., Freundlich, Langmuir, and Dubinin–Radushkevich (D-R) isotherms successfully. The thermodynamics studies indicate that sorption increases with rise in temperature, entropy driven, and endothermic chemisorption. The nature of the sorption mechanism of Hg(II) ions with dithizone and PUF has been discussed and the composition of the adsorbed complex has been predicted. The effect of different foreign cations and anions has been investigated. The data indicates that only EDTA, thiosulphate, and cyanide are interfering. The method was applied on different synthetic mixtures and saline solution to test the selectivity of the new method for the abatement of Hg(II) ions from mixed solvent system.
THE KECKITE PROBLEM AND ITS BEARING ON THE CRYSTAL CHEMISTRY OF THE JAHNSITE GROUP: MÖSSBAUER AND ELECTRON-MICROPROBE STUDIES

Keckite is considered to be a member of the jahnsite group, though the formula originally given does not conform to the general formula of minerals of that group. In this study, samples of keckite from different localities, including the type locality, have been investigated. Keckite is a special member of the jahnsite group containing trivalent iron not only at the C site but also at the B site, as proven by Mossbauer spectroscopy. The chemical composition was determined by electron-microprobe analysis, and the H 2O content, by differential thermogravimetry. A new formula for keckite is proposed: CaMn(Fe 3+,Mn) 2 Fe 3+ 2(OH) 3(H 2O) 7[PO 4] 4.
Cephazoline sodium release from poly(N‐isopropyl acrylamide‐co‐N,N‐dimethylacrylamide) hydrogels

Hydrogels are hydrophilic polymers that swell to an equilibrium volume in the presence of water, preserving their shape. The dynamic swelling behavior of poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) [poly(NIPA-co-DMA)] copolymers at 37°C was investigated. It was observed that the swelling degree in the copolymers decreases with the N-isopropylacrylamide content. In addition, the liberation mechanism was found to be Fickian. Diffusion coefficients according to Fick′s law as a function of the N-isopropylacrylamide concentration and results of the release process are reported. The kinetics of cephazoline sodium release from poly(NIPA-co-DMA) hydrogels with different compositions was studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3433–3437, 2004
Dimensional Analysis of Reaeration Rate in Streams

Atmospheric reaeration at the free surface of lakes and streams is a relevant process for water quality, thus the amount of oxygen transferred to the water body should be carefully estimated. Recent studies have demonstrated that available equations for estimation of the reaeration rate offer a poor fit with field data different from those for which each equation was originally developed. Thus, none of the available equations is applicable to all stream hydrodynamic conditions; on the contrary, they remain stream-specific, probably since some parameters involved in the process have been neglected in their formulation and their expressions are too simplistic. This paper proposes a comprehensive approach to the mass-transfer process at the air-water interface that is based on dimensional analysis. Careful inspection of equations in the literature shows that the mass-transfer process at the air-water interface has been affected by 14 different parameters. The application of dimensional analysis produces, for a wide rectangular section if wind speed is negligible, a dimensionless equation for the mass-transfer rate, where this rate is a function of the Froude number, channel slope, Reynolds number, Sherwood number, Weber number, and relative roughness. This expression is further developed to address the reaeration process in streams and rivers. As a result, at a fixed temperature, the dimensionless reaeration rate KaND ~where ND denotes nondimensional! is finally a function of only the Froude number, channel slope, Reynolds number, and relative roughness. Moreover, the application of the Darcy-Wiesbach equation allows this dimensionless rate KaND to be considered as a function of only three of the aforementioned parameters. This result provides a comprehensive approach to the reaeration process that can also explain the unreliability of the literature equations available up to now.
Cyanide-free preparation of gold nanowires: controlled crystallinity, crystallographic orientation and enhanced field emission

The environmentally friendly preparation of nanomaterials with controlled structural features represents a development trend of nanoscience and nanotechnology. In this work, using a cyanide-free bath, gold nanowires with controlled crystallinity and preferred crystallographic orientation have been prepared by electrochemical deposition in home-made polycarbonate ion track-etched templates. Single-crystal and polycrystal gold nanowires with preferred orientations along the [111] and [100] directions have been obtained by selecting fabrication parameters. The influence mechanisms of nanopore diameter, applied voltage, and deposition temperature on structural properties are proposed. In addition, single-crystal nanowires with [100] preferred orientation show enhanced field emission, which may be attributed to their single-crystal structure and the lower work function of loosely packed crystal planes.
Supercritical fluid extraction of volatile and non-volatile compounds from Schinus molle L.

Schinus molle L. , also known as pepper tree, has been reported to have antimicrobial, antifungal, anti-inflammatory, antispasmodic, antipyretic, antitumoural and cicatrizing properties. This work studies supercritical fluid extraction (SFE) to obtain volatile and non-volatile compounds from the aerial parts of Schinus molle L. and the influence of the process on the composition of the extracts. Experiments were performed in a pilot-scale extractor with a capacity of 1 L at pressures of 9, 10, 12, 15 and 20 MPa at 323.15 K. The volatile compounds were obtained by CO2 supercritical extraction with moderate pressure (9 MPa), whereas the non-volatile compounds were extracted at higher pressure (12 to 20 MPa). The analysis of the essential oil was carried out by GC-MS and the main compounds identified were sabinene, limonene, D-germacrene, bicyclogermacrene, and spathulenol. For the non-volatile extracts, the total phenolic content was determined by the Folin-Ciocalteau method. Moreover, one of the goals of this study was to compare the experimental data with the simulated yields predicted by a mathematical model based on mass transfer. The model used requires three adjustable parameters to predict the experimental extraction yield curves.
Thermal Properties of Supercritical Carbon Dioxide by Monte Carlo Simulations

We present simulation results for the volume expansivity, isothermal compressibility, isobaric heat capacity, Joule-Thomson coefficient and speed of sound for carbon dioxide (CO 2 ) in the supercritical region, using the fluctuation method based on Monte Carlo simulations in the isothermal-isobaric ensemble. We model CO 2 as a quadrupolar two-center Lennard-Jones fluid with potential parameters reported in the literature, derived from vapor-liquid equilibria (VLE) of CO 2 . We compare simulation results with an equation of state (EOS) for the two-center Lennard-Jones plus point quadrupole (2CLJQ) fluid and with a multiparametric EOS adjusted to represent CO 2 experimental data. It is concluded that the VLE-based parameters used to model CO 2 as a quadrupolar two-center Lennard-Jones fluid (both simulations and EOS) can be used with confidence for the prediction of thermodynamic properties, including those of industrial interest such as the speed of sound or Joule-Thomson coefficient, for CO 2 in the supercritical region, except in the extended critical region.
Hydrophobic Modification of Polymer Surfaces via “Grafting to” Approach

Hydrophobic grafted polymer layers were permanently anchored from the melt onto poly(ethylene terephthalate) (PET) and nylon substrates modified with air plasma and poly(glycidyl methacrylate) (PGMA) anchoring layer. Polypentafluorostyrene (PPFS) of different molecular weights with an end carboxyl group was used for the grafting. Atomic force microscopy imaging revealed that, in general, the grafted chains evenly covered all substrates. Thickness of the grafted layer increased with temperature and time of grafting. To reach a significant level of grafting and consequently high hydrophobicity temperature above 140°C, 5 min of grafting had to be used. For longer grafting time (1 h) the hydrophobicity could be reached at 120°C. The thickness of the grafted layer should be at least 2–3 nm to attain the high water‐contact angle. The polymer grafting technique developed could be readily applied to surface modification of fibers and textiles leading to generation of hydrophobic fibrous materials. In Commemoration of the Contributions of Professor Valery P. Privalko to Polymer Science.
Thermodynamics of Al — Si and Al — Ge — Si liquid alloys: Enthalpies of formation by high temperature calorimetry

The enthalpies of formation of Al — Si and Al — Ge — Si liquid alloys were investigated by high temperature calorimetry. A new mixing and stirring device was designed in order to take into account the physicochemical properties of the metals involved. — The enthalpy of formation of the ternary alloys were found satisfactory using the Kohler's equation; the quasi-ideality assumption for the binary Ge — Si revealed verified within the experimental accuracy.
Chemical and Organic Amendments for Controlling Potato Bacterial Wilt

acterial wilt disease caused by Ralstonia solanacearum is one of the most important and widespread bacterial diseases of solanaceous crops in tropical, sub-tropical areas and some warm regions. The present research was aimed to evaluate some chemical and organic amendments, individually or in combinations, for controlling potato bacterial wilt disease under greenhouse and field conditions. Application of chemical amendments, i.e. urea, ammonium nitrate and ammoniated superphosphate, as well as organic amendments, i.e. garlic, cabbage and camphor dry leaves, either individually or in mixture, reduced severity of potato wilt under greenhouse and field conditions compared to the check treatment. Efficiency of tested amendments increased with increasing their application rates. In greenhouse experiments, chemical amendment was more effective than organic ones in disease control. Moreover, mixed treatments was more effective than their individual applications. Meantime, urea (as a chemical amendment) and dry garlic leaves (as an organic amendment), either individual or in mixture, were the most effective. Under field conditions, the population of R. solanacearum in rhizosphere, crown and potato tubers, along with severity of wilt were decreased, meanwhile potato yield was increased with mixing chemical and organic amendments compared to the check. Mixing urea with dry garlic leaves was the most effective to reduce population of R. solanacearum and to increase the yield, but other mixtures were moderately effective.
Plasma electrolyte concentrations in normal and streptozotocin-induced diabetic rats treated with extracts of Triplochiton scleroxylon K. Schum

This study investigated the effect of aqueous and ethanolic extracts of Triplochiton scleroxylon on plasma electrolyte concentrations in normal and streptozotocin-induced diabetic rats after 28 days of administration. The rats of Wistar strain used, weighed between 130 to 186 g. Test rats were administered 200 mg/kg body weight of extracts (p. o) twice daily. Plasma samples were analysed for all experimental parameters by methods requiring spectrophotometry. Analysis of data showed that extracts caused a significant increase in plasma sodium relative to normal control. Increase in bicarbonate concentration obtained was not significant. Plasma chloride and potassium concentrations however, decreased in treated rats when compared to normal control (P<0.05). In untreated diabetic rats plasma electrolyte concentrations were observed to decrease. Treatment with aqueous and ethanolic extracts of Triplochiton scleroxylon significantly reversed the decrease in the concentrations of plasma electrolytes (Na + , K + , Cl - and HCO3 - ) caused by streptozotocin-induced diabetes when compared to diabetic control (P<0.05). Histological analysis of tissues showed no adverse changes in the hearts, kidneys and livers of normal rats.
BIOFILM INHIBITORY EFFECT OF SILVER NANOPARTICLES COATED CATHETER AGAINST STAPHYLOCOCCUS AUREUS AND EVALUATION OF ITS SYNERGISTIC EFFECT WITH ANTIBIOTICS

The present study was undertaken to evaluate pharmacological inhibition of biofilm of clinical isolate of Staphylococcus aureus on silver nanoparticles coated catheter under in vitro condition and the synergistic effect of nanoparticles with antibiotics was studied. Silver nanoparticles synthesized by chemical reduction method were coated on the catheter adopting simple dispersion method. Initially biofilm inhibitory effect was studied with spectrophotometric method and the biochemical composition of biofilm matrix mainly total carbohydrates and protein studied. Silver nanoparticles synthesized by chemical reduction of silver nitrate with sodium borohydride were coated on the catheter was characterized by surface topography of catheter by scanning electron microscopy which reveals complete dispersion of the nanoparticles on the fibre surface of the catheter and the size, shape of the particles shows uniform spherical particles with the size of 40-60 nm. Distinct effect of biofilm inhibition was recorded in the nanoparticles coated catheter and maximum inhibition was observed during 24 th hour of incubation Surface topography of nanoparticles and nanoparticles with antibiotics coated catheter with scanning electron microscopy reveals the complete degeneration of the biofilm whereas biofilm matrix biochemical composition mainly total carbohydrates and total protein was highly reduced. Biofilm inhibition rate and reduction of biofilm matrix biochemical composition was increased in nanoparticles with all the tested antibiotics treatment which suggests the synergistic effect.