Miracle-dz/UniFAR-FTUs huggingface dataset:
Theoretical and Experimental Study on Membrane Distillation in the Concentration of Orange Juice

Membrane distillation is a relatively new membrane process in which two solutions at different temperatures are separated by a microporous hydrophobic membrane. This process can be used to concentrate fruit juices. The transport phenomena involved in membrane distillation for the concentration of fruit juices are described. Heat and mass transfer balances have been formulated, accounting for the geometry and morphology of the membrane and the properties of juice solutions. An experimental study of the concentration of orange juice with a hydrophobic poly(vinylidene fluoride) flat membrane is also presented in this paper
Synthesis of Sr2Fe1-xMnxNbO6-δ Powders and their Stability as Electrode of Solid Oxide Electrolysis Cell

Double-perovskite Sr2Fe1-xMnxNbO6-δ (x = 0, 0.1, 0.2, 0.3, 0.5, 0.8) (SFMN) powders which will be applied to the electrode of solid oxide electrolysis cells (SOEC) were synthesized by Solid State Reaction Method. The mixed oxide powders SrCO3, Fe2O3, MnO2 and Nb2O5, were homogeneously calcined at different temperatures and in different atmospheres. The influence of the preparation process on the structure and the morphology of the powder were investigated by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It is found that the formation of perovskite structure is directly related to the content of Mn and calcining temperature. Controllable synthesis of pure phase of double perovskite powders was realized after calcining for12h at 1150 °C in air. Moreover, the experimental results show that the perovskite structure of SFMN is stable in whether oxidizing or reducing atmosphere, which indicates that this material has a potential to be used as electrode of solid oxide electrolysis cell.
A time-dependent approach to the kinetics of homogeneous nucleation

We present a time‐dependent model for homogeneous nucleation and derive a time‐dependent solution to the coupled growth‐rate equations for molecular cluster concentrations. A correction to the monomer concentration growth‐rate equation is applied, which accounts for the gain and loss of molecules by all cluster populations. The condensation rate used considers all embryos to be in motion, rather than assuming that only the monomers move. In order to allow for size‐dependent variations in a cluster’s surface tension, the evaporation rate incorporates the revised parametrization of Laaksonen et al. [Phys. Rev. E 49, 5517 (1994)] of the homogeneous nucleation theory of Dillmann and Meier [J. Chem. Phys. 94 3872 (1991)]. Eigenvalue analysis illuminates how the steady‐state is approached from the transient period and allows us to estimate the accuracy of a steady‐state approximation. It is shown that the distributions of clusters predicted by this theory generate nucleation currents that are more accurate than.
THE USE OF MOUNDS OF THE TERMITE MACROTERMES FALCIGER (GERSTÄCKER) AS A SOIL AMENDMENT

Summary Twelve termite mounds and adjacent Ah and Ap horizons were sampled at three sites near Salisbury, Rhodesia. The mass of termite mounds occupied by M. falciger at one site was estimated at 620 t/ha, and contained the following amounts of nutrients expressed as percentages of the amounts in mounds and Ap horizon combined: extractable Ca 95%, mineral N 81% extractable K 69%, and available P 69%. Pot experiments using perennial ryegrass gave higher dry matter yields from termite mounds than from the Ap and Ah horizons. Crop production could therefore be increased by mixing termite mounds with the soil.
Clay sediment geopolymerization by means of alkali metal aluminate activation

In this work a clay sediment from a reservoir was employed for the synthesis of geopolymers. The sediment was calcined at 650 and 750 °C for 1 h to ensure the conversion of aluminium coordination from octahedral to tetrahedral. The sediment was characterized by means of X-ray fluorescence, X-ray diffraction, thermogravimetry, mercury intrusion porosimetry and scanning electron microscopy. After calcination, the sediment was submitted to X-ray diffraction, mercury intrusion porosimetry and scanning electron microscopy. Strongly alkaline sodium and potassium aluminate solutions were used to start the polycondensation reaction responsible for geopolymer formation. The initial alkali metal hydroxide concentrations of these solutions were 17, 15 (only Na), 13, 11 and 8.5 M. Polycondensation was carried out at 60 °C for times ranging from 15 min to 28 d. The geopolymer products obtained in all the experimental conditions tested were submitted to the quantitative determination of the extent of polycondensation through mass increase and loss on ignition, as well as to qualitative characterization by means of FT-IR spectroscopy. A reduced set of samples activated with solutions corresponding to initial [NaOH] 13 M and [KOH] 11 M and cured at 60 °C for 3 and 14 d were used for the determination of apparent density and unconfined compressive strength. These samples were also characterized by means of mercury intrusion porosimetry and scanning electron microscopy. The results have indicated that the development of preformed building materials starting from reservoir sediment, although requiring accurate mix design, can be possible by means of alkali metal aluminate activation.
Anion-Selective Field-Effect Transistor Sensor Using RF-Sputtering Film of Alkali Metal-Free Lead Phosphate Glass Containing Silver Oxide.

New ion-selective field-effect transistors (ISFET) for an anion responsive type probe are described. The gate surface of the ISFET was coated by radio-frequency sputtering with an alkali metal-free phosphate glass containing silver oxide. This ISFET responded to S2O32−, SCN−, I−, NO2−, SO32−, and Cl−, but not to NO3−, ClO3−, SO42−, and HPO42−. A radiation damage of sputtering products is generated in the dielectric layer and at the interface of the gate channel, and the static characteristics of the glass coated ISFETs were used to evaluate the radiation damage. Optimal RF sputtering gas composition, dc floating bias from anode to substrate, RF power density, and sputtering time were argon 90%/oxygen 10%, −70 V, 0.88 W cm−2, and up to 4 h, respectively.
Detection of nitrogen and phosphorus nutrient status in bermudagrass using spectral radiance

Abstract Nitrogen (N) and phosphorus (P) are two of the most limiting nutrients for crop production. Because of this, continued interest focuses on improving N‐and P‐use efficiency. Spectral radiance measurements were evaluated to identify optimum wavelengths for dual detection of N and P status in bermudagrass (Cynodon dactylon L.). A factorial arrangement of treatments (0, 112, 224, and 336 kg N ha‐1 and 0,29, and 58 kg P ha‐1) was applied to an established bermudagrass pasture for further study using a randomized complete block design. A wide range of spectral radiance measurements (276–831 nm) was obtained from each plot using a PSD 1000 Ocean Optics fiber optic spectrometer. The resulting spectra were partitioned into 10‐nm bands. Added indices were generated to test for correlation of N and P content with spectral radiance. The 435‐nm band (430–440 nm) was found to be independent of N and P treatment, and as a covariate, significantly decreased residual error. Using 435 nm as a covariate, it was fou.
Encapsulation of Polyoxotungstate into Dendrimers by Ionic Bonding and Their Use As Oxidation Catalyst

A family of 36-armed dendrimers containing six internal amino groups was synthesized and used to incorporate polyoxometalates (POMs) into their structures by ionic bonding. Allyl-terminated dendrimer 17 (with oxidizable end groups) and methylphenyl-terminated dendrimer 18 (with non-oxidizable end groups) were used for these studies. It was found that the electrostatic incorporation of the tri-anionic POM [PO4{WO(O2)2}4]3− into the methylphenyl-terminated dendrimer 18, in an acidic medium, leads to the dendritic POM hybrid 19, bearing two POM units in its structure. In contrast, attempts to encapsulate POMs into allyl-terminated dendrimer 17 gave unsatisfactory results. Indeed, the epoxidation kinetics of the 36-olefinic terminated dendrimer 17 was too slow, and the expected 36-epoxy-dendritic POM framework 20 was not obtained. Lengthening the reaction up to six hours led to the decomposition of POM species. The solubility in organic solvents of the dendritic POM hybrid 19, combined with its NMR and infrared data, indicate that POM units are clearly connected to the dendritic structure. The catalytic performance of this hybrid material in the oxidation of cyclooctene shows that the properties of POM are retained. The POM-encapsulated dendrimer 19 was found to be an effective catalyst in the oxidation of cyclooctene.
INCREASES IN THE CARBON AND NITROGEN CONTENTS OF TROPICAL SOILS UNDER NATURAL FALLOWS

Summary The rate of increase of humus carbon in soils rested under natural fallows has been calculated, assuming that the rate of decomposition of the humus carbon is proportional to the amount present, and that the rate of addition, by humification of litter and roots, remains constant. The rate of decomposition has been derived from a knowledge of the maximum humus level the soil attains under the fallow vegetation, and the rate of addition has been estimated from data on litter production. The rate of increase of nitrogen has also been calculated assuming that the C/N ratio in the soil remains constant. Under the native practice of shifting cultivation in forest the alternation of cropping and fallowing leads to relatively small fluctuations in soil humus at about 75 per cent. of the maximum level. The rates of increase of soil nitrogen at this level are between 20 and 50 lb. per acre per annum in forest and 4 and 10 lb. per acre per annum in savannah. Rates at other levels for which the assumptions made are valid may readily be calculated from the data presented. It is shown that provided vegetation re-establishes itself rapidly a crop: fallow ratio of about 1:3 should maintain the humus level in forest soils at the 75 per cent. of equilibrium level, a result which accords well with experience.
On the Estimation of Parameters and Reliability Functions of a New Two-Parameter Lifetime Distribution based on Type II Censoring

We consider here the generalization of the Bilal distribution proposed by Abd-Elrahman (2017) by zeroing in on two measures of reliability, R(t) and P, based on type II censoring. We obtain point estimators namely, λ and θ, of the above said distribution, when both parameters of the distribution are unknown. Maximum likelihood estimators (MLEs), Bayes estimators (BEs) and Lindley’s approximation for the Bayes estimators are proposed. By using independent noninformative type of priors for the unknown parameters Bayes estimators are derived. Although the proposed estimators cannot be expressed in closed forms, these can be easily obtained through the use of numerical procedures. The performance of these estimators is studied on the basis of their mean squared error (MSE), computed separately under LINEX loss function (LLF) and squared error loss function (SELF) through Monte-Carlo simulation technique.
Stable Silver Clusters and Nanoparticles Prepared in Polyacrylate and Inverse Micellar Solutions

Silver clusters and nanoparticles were prepared by reduction of silver nitrate by sodium borohydride in water, in the presence of polyacrylate ions, and in inverse micellar solutions consisting of Laureth 4 and water. The kinetics of formation of Ag42+ aggregates and Ag9+ in the presence of polyacrylate ions could be observed by the stopped-flow technique, and the characteristic UV absorption spectra of the respective stable clusters were recorded. The formation of these species was critically dependent on the manner in which reactants were combined. The silver nanoparticles prepared in the inverse micellar solutions using different mixing procedures were characterized via UV−vis spectra, dynamic light scattering, and transmission electron microscopy. The results showed that the procedure of adding aqueous sodium borohydride solution into the inverse micellar solution containing silver nitrate gave the most uniform spherical silver nanoparticles. The reaction kinetics of this procedure was investigated th.
Size Correlation of Optical and Spectroscopic Properties for Gold Nanoparticles

While the optical and spectroscopic properties of gold nanoparticles are widely used for chemical, bioanalytical, and biomedical applications, the study of the size correlation with these properties for nanoparticles in solutions is rather limited. This paper describes the results of a systematic study of such a correlation for gold nanoparticles with diameters ranging from 10 to 100 nm in aqueous solutions. The high monodispersity of these nanoparticles permitted a meaningful correlation of the particle size with the surface plasmon (SP) resonance band properties and the surface-enhanced Raman scattering (SERS) spectroscopic properties. This correlation is compared to the results from the simulation based on Mie theory. The close agreement between the experimental and the theoretical results provides insight into the validity of determining the wavelength of the SP resonance band as a measure of the particle size. The size correlation with the SERS intensity from the adsorption of 4-mercaptobenzoic acid .
Simultaneous measurement of strain and temperature using Fabry–Pérot interferometry and antiresonant mechanism in a hollow-core fiber

A fiber-optic sensor for the simultaneous measurement of strain and temperature is proposed and experimentally demonstrated based on Fabry–Perot (FP) interference and the antiresonance (AR) mechanism. The sensor was implemented using a single-mode fiber (SMF)–hollow-core fiber–SMF structure. A temperature sensitivity of 21.11 pm/°C was achieved by tracing the troughs of the envelope caused by the AR mechanism, and a strain sensitivity of 2 pm/µe was achieved by detecting the fine fringes caused by the FP cavity. The results indicate that the dual-parameter sensor is stable and reliable.
Self-consistent modeling of resonant PL in InGaN SQW LED-structure

The measurement of the bias and temperature dependent photoluminescence, photocurrent and their decay times allows to deduce important physical properties such as barrier height, electron-hole overlap and the magnitude of the piezoelectric field in InGaN quantum wells. However the analysis of these experiments demands for a detailed physical model based on a realistic device structure which is able to predict the measured quantities. In this work a selfconsistent model is presented based on a realistic description of the alloy and doping profile of a green InGaN single quantum well light emitting diode. The model succeeds in the quantitative prediction of the quantum confined Stark shift and the associated change in the electron-hole overlap measured via the change in the bimolecular decay rate using literature parameters for the piezoelectric constants. The blue shift of the emission under forward current conditions can be attributed to the carrier induced screening of the piezoelectric charges as predicted by the model. The photocurrent is calculated via thermionic tunneling through the barriers using a WKB-approximation and the calculated potential profile for the tunneling barrier. From the fact that the bias and temperature dependence of the experimentally observed photocurrent cannot be described by the thermionic tunneling model even though the theoretical potential profile fits excellent to the luminescence data, we conclude that the carrier escape is dominated by a different mechanism such as defect- or phonon-assisted tunneling.
Rapid and quantitative analysis of pesticides in fruits by QuEChERS pretreatment and low-temperature plasma desorption/ionization orbitrap mass spectrometry

Ambient desorption/ionization high-resolution mass spectrometry (ADI-HR-MS) is a powerful method for the analysis of complex samples. Recently, direct analysis in real time (DART) MS and low-temperature plasma probe (LTP) MS demonstrated potential in direct qualitative pesticide residue screening and quantitative analysis of pesticides in liquid extracts. In the present study, a LTP-HR-MS method for quantitative pesticide residue analysis in fruit extracts was developed and evaluated with respect to the European Union (EU) legislation on pesticides. In particular, this study focused on pesticides in different fruit matrices that were reported to often exceed legal maximum residue levels (MRLs) in Germany in the past (namely acetamiprid, cyprodinil, fenhexamid, and fludioxonil; see report on of the German Federal Office of Consumer Protection and Food Safety in 2009). After method optimization, pesticides in spiked and unspiked fruit QuEChERS extracts were identified successfully by LTP-Orbitrap-MS via accurate mass measurements (<4 ppm). The method is considered useful for MRL verification. Matrix-matched calibration was applied for quantification because it was found that the fruit matrix (still present during extract analysis) has a significant effect on analyte ion abundance. Linear working ranges greater than four orders of magnitude were achieved. Limits of quantification ranged from 0.001 mg kg−1 to 0.07 mg kg−1 (which is significantly below permitted MRLs). Measurement precision was below 15% and method precision was typically close to 14% relative standard deviation. Finally, the validated LTP-HR-MS method was tested with unspiked fruit samples bought from a local grocery store. Pesticide residues of cyprodinil and fludioxonil (0.003–0.03 mg kg−1) were readily detected. These results were directly compared to a standard liquid chromatography electrospray HR-MS method and found to be in good agreement.
Fabrication of sub‐10 nm structures by lift‐off and by etching after electron‐beam exposure of poly(methylmethacrylate) resist on solid substrates

Sub‐10 nm structures were fabricated by lift‐off and by etching following electron‐beam exposure of poly(methylmethacrylate) (PMMA) resist on solid semiconductor substrates. Electron beam lithography at 80 kV with a beam diameter smaller than 5 nm was used to expose PMMA resist on either Si or GaAs substrates. The exposed resist was developed with a 3:7 cellosolve:methanol mixture in an ultrasonic bath for 5 s followed by rinsing in IPA and blown dry with pure nitrogen. Ultrasonic agitation during development was found to be essential for forming sub‐10 nm structures in PMMA. The patterned PMMA resist was used either as a lift‐off mask or an etching mask and successful transfer of the pattern to the substrates was achieved. For lift‐off an ionized beam deposition method, which gives smaller grain size and better adhesion of the metal film to the substrate, was used to deposit a layer of AuPd. Metal dots with sub‐10 nm diam and metal structures with sub‐10 nm gaps were fabricated. For sub‐10 nm etched stru.
Structural, Electronic, and Mechanical Properties of Single-Walled Halloysite Nanotube Models

Halloysite is a clay mineral with stoichiometry Al2Si2O5(OH)4·nH2O that can grow into long tubules and is chemically similar to kaolinite. In this work we present a systematic study on the stability, electronic, and mechanical properties of zigzag and armchair single-walled halloysite nanotubes by means of the self-consistent charge density-functional tight-binding method (SCC-DFTB). The detailed analysis is focused on structural properties, strain energy, and band gap as a function of tube radii and Mulliken charge distribution. The strain energy of halloysite nanotubes does not have a monotonic character and the most stable structures should be observed in the region of radii above 24 A, in agreement with experimental data. Analysis of the electronic density of states shows that all tubes are insulators. Our calculations predict that single-walled halloysite nanotubes have Young modulus in the same order of imogolite and inorganic nanotubes, but smaller than that of carbon nanotubes. Even though most of.
Photoreactivity models for titanium dioxide with water

Abstract The present work considers the mechanisms of the reactivity of water with titanium dioxide, which, due to its high chemical stability, is one of the most promising photoelectrode materials for photoelectrochemical water splitting. The reactivity is considered in terms of two models. The first model considers the reaction between a water molecule and a Ti vacancy at the surface of an ideal rutile structure. The second reactivity model considers the charge transfer between a bi-dimensional surface layer and water molecules.
A Pressure Drop Model for Spacer Grids with and without Flow Mixing Vanes

In summary, the proposed model showed the reasonably accurate predictions for various grids investigated here. It yields also better predictions than others do. Even some improvements are needed in the model, however, it is concluded that the proposed model for pressure drop can provide sufficiently good approximation for grid optimization and design calculation in advanced grid development.
Evolución de titulación en Educación Superior de Chile. Periodo 1999-2008.

Este estudio profundiza en la informacion disponible en el Compendio Historico de TItulacion en Educacion Superior referido a los anos 1999 al 2008, analizando la evolucion durante este periodo. Asi tambien, el incremento es analizado en funcion de una serie de variables de interes, tales como: genero, tipo de institucion, tipos de programas, region, etc.
Prevalence of deep caries in preschoolers who underwent either scheduled or emergency dental general anesthesia. Does toothache make a difference? A retrospective analysis

The Federal State of Tirol, Austria, has been presenting a high level of education and commitment in general and oral health issues [12,13]. However, a polarization of caries in children of high-risk groups (frequently coming from families presenting a low educational level or a migratory background) has occurred [14]. A lack of oral health literacy and language barriers may be causative. Caries and/or pain constituted the reasons for seeking dental attendance in the preschoolers admitted to dental general anesthesia (DGA) who were investigated in this study [15,16]. DGA presents an accepted treatment method in individuals who are (due to infantile incomprehension, dental anxiety, intellectual and/or physical disablement, or systemic diseases) unamenable to routine dental treatment, even though it requires high expenditure and implicates the risk of anesthetic complications [17-19]. DGA has been shown to enhance children’s oral health-related quality of life and dental behavior [20-24]. In acute settings, DGA provides a rapid onset of action and an optimal titration of anesthetics [25]. However, emergency DGA presents an organizational challenge with respect to the 24/7 provision of pre-, periand postoperative care requiring the respective medical and nursing staff. For the children ́s benefit, scheduled DGA in non-pain patients displaying carious lesions seems preferable to a stressful emergency procedure, also with respect to the possible conservation/restoration of carious teeth instead of tooth extractions. The question of interest in this study was, if the presence of toothache is associated with higher numbers of deeply carious primary teeth. The null hypothesis was that the prevalence of deep caries is equal Abstract