Miracle-dz/UniFAR-FTUs huggingface dataset:
Mixing of viscoelastic fluids with helical-ribbon agitators. I — Mixing time and flow patterns

Batch mixing of viscous fluids with helical-ribbon agitators in 2.4 liter and 13 liter vessels has been studied for agitator speeds up to 200 RPM. Seven different agitators of different dimensions were employed in this work. Mixing times were measured using a decoloration technique and circulation times were determined by the tracer bead method. In addition, velocity profiles were obtained from streak photographs using selective illumination of the vessel and PVC powder as tracer particles. It was found that the mixing times of Newtonian fluids, which agreed with previously published data, were considerably (3 to 7 times) shorter than those of the viscoelastic fluids. The mixing time was strongly affected by the fluids' elasticity; increasing as the fluid elasticity increased. The velocity profiles were qualitatively similar for all the fluids but showed decreased axial circulation and increased circumferential flow as fluid elasticity increased. However, mixing is not only a function of the axial circulation (impeller pumping rate) but also is a function of the perturbations superimposed on the main flow. A simple, first approximation model based on the impeller geometry and flow patterns is proposed to correlate the circulation capacity and mixing time data for the various geometries studied. On a etudie, en employant des vitesses d'agitation atteignant 200 tours a la minute, le melange discontinu de fluides visqueux assure par des agitateurs a ruban helicoidal dans des vaisseaux de 2.4 litres et 13 litres; on a utilise a cette fin sept agitateurs differents de dimensions variees. On a mesure les temps de melange par une methode de decoloration et determine les temps de circulation au moyen d'une methode a base de perles marquees. On a, en outre, obtenu des profils de vitesse a partir de photographies avec stries, en utilisant un eclairage selectif du vaisseau et de la poudre de chlorure de polyvinyle qui servait pour les particules marquees. On a trouve que les temps de melange des fluides newtoniens, qui correspondaient a ceux qui ont deja ete publies, etaient bien plus faibles (3 a 7 fois) que les temps de melange des fluides visco-elastiques. L'elasticite des fluides a considerablement affecte le temps de melange, qui augmentait avec celleci. Les profils de vitesse se sont averes qualitativement semblables pour tous les fluides, mais ils ont indique une circulation axiale moindre et un ecoulement circonferentiel accru, a mesure que l'elasticite des fluides augmentait. Toutefois, le melange est une fonction non seulement de la circulation axiale, (taux de pompage du rotor), mais aussi des perturbations sur-imposees sur l'ecoulement principal. On propose un modele simple et fournissant une premiere approximation, lequel est base sur la geometrie du rotor et les types d'ecoulement, en vue d'etablir des correlations entre les resultats relatifs a la circulation et aux temps de melange, dans le cas des diverses formes geometriques etudiees.
Dinâmica do nitrogênio no solo e produção de fitomassa por plantas de cobertura no outono/inverno com o uso de dejetos de suínos

O uso de dejetos de suinos que antecede a instalacao das plantas de cobertura de solo no outono/inverno e uma pratica cada vez mais frequente na regiao Sul do Brasil, cujos efeitos no solo e nas plantas sao ainda pouco avaliados pela pesquisa. O objetivo deste trabalho foi avaliar a dinâmica do N no solo e a producao de plantas de cobertura com o uso de dejetos de suinos no outono/inverno. O trabalho foi desenvolvido durante o ano agricola de 2000, em area experimental do Departamento de Solos da UFSM, RS. O delineamento experimental foi de blocos ao acaso com parcelas subdivididas e tres repeticoes. As parcelas foram constituidas por aveia preta, pelo consorcio de aveia preta (30 %) + ervilhaca comum (70 %) e pela vegetacao espontânea da area (pousio). Nas subparcelas, foram aplicadas quatro doses de dejetos de suinos (0, 20, 40 e 80 m3 ha-1). No solo, foram avaliados, em sete datas, os teores de N mineral (N-NH4+ e N-NO2- + N-NO3-) nas camadas de 0-5, 5-15, 15-30 e 30-60 cm. Nas plantas de cobertura e na vegetacao espontânea, avaliaram-se a producao de materia seca e a sua concentracao em N, P e K. A quantidade de N mineral do solo aumentou com a aplicacao de dejetos liquidos, nao tendo a dinâmica do N diferido entre aplicar os dejetos sobre os residuos culturais remanescentes de aveia/milho ou sobre aqueles da vegetacao espontânea/milho. Na dose de 80 m3 ha-1 de dejetos, houve evidencias de perda de N-NO3- por lixiviacao, para alem da profundidade de 60 cm, sendo maiores no sistema vegetacao espontânea/milho do que no sistema aveia/milho. Com o uso dos dejetos, aumentou a producao de materia seca, bem como o acumulo de N, P e K nas plantas de cobertura. Na aveia solteira, o aumento na producao de materia seca decorrente do uso de 40 m3 ha-1 de dejetos, em relacao ao tratamento sem dejetos, foi de 2,7 t ha-1. No consorcio de aveia + ervilhaca, o aumento na quantidade aplicada de dejetos favoreceu o crescimento da aveia em detrimento da ervilhaca, ocorrendo o melhor equilibrio entre a producao de fitomassa e a adicao de N na dose de 20 m3 ha-1 de dejetos. Os resultados deste estudo evidenciam a eficiencia das plantas de cobertura no outono/inverno em ciclar nutrientes fornecidos pelos dejetos de suinos e a importância da utilizacao de especies com elevado potencial de producao de materia seca e que sejam exigentes em N.
Viscosity of nanofluids: particle shape and fractal aggregates

Colloidal dispersions of nanoparticles in thermal base fluids are known to alter their spherical shapes thereby affecting their surface properties. This aspect has been investigated with respect to the effective viscosity of nanofluids presuming the particles to acquire the shape of prolate spheroid. Also, the contributions of the interfacial layer formed around these particles and their possible agglomeration has been taken in to account. The analysis has been carried out by modifying the Krieger and Dougherty model. The relative viscosity of these nanofluids has been computed as a function of volume fraction, particle size and the eccentricity of the particle. The model also incorporates the concept of fractal dimensions. The results thus obtained compare significantly well with the available experimental data and reaffirms an improvement over earlier models.
Less Pain, More Gain? The Effect of Exports on Workplace Safety

This study examines the effect of exports on worker safety and health in the US during the last two decades. We use foreign countries’ unilateral liberalization as an instrument to capture demand shocks on US exports to the world. Our two-stage estimates with establishment fixed effects suggest that a $1,000 increase in exports per worker decreased the workplace injury rate by a significant 0.5%, which implies an annual reduction of about 4,000 injuries among manufacturing workers. The reduction in injuries is more salient among establishments with higher injury rates, indicating an improvement in the inequality of working conditions. The improvement in working conditions might come from more investment in advanced equipment and better compliance of safety and health regulations.
Determinants of patient survival following acute Ebola virus infection

The 2013-2016 outbreak of Zaire ebolavirus (EBOV) in West Africa was unprecedented in scale and has sparked a great deal of interest into the pathogen. EBOV is the most pathogenic species in the family Filoviridae. Early symptoms are non-specific and flu-like, but these rapidly dissolve into systemic issues, frequently resulting in death. Fatal infections are associated with uncontrolled inflammation, while survivors have an initial robust antiviral response followed by an effective antigen-specific response. However, there are a myriad of other factors influencing patient outcome, including viral load and co-infections. The elucidation of these factors could have major therapeutic implications. RNA-sequencing via Illumina and Nanopore platforms was performed on the diagnostic samples of patients during the outbreak in order to explore many facets of EBOV biology. The nature of these samples allowed investigation into the determinants of patient outcome following Ebola virus disease (EVD). Blood was taken from acutely ill individuals at a time when it was not known whether they would survive and clear the infection or succumb to it. These data allowed investigation into viral genome variation and the potential role of viral quasispecies in patient outcome, as well as the study of defective interfering particles in vitro – a potential mechanism for viral persistence. The immune response to the pathogen was assessed via the comparison of gene expression and predicted immune cell profiles. Bioinformatic techniques were also employed to search these diagnostic samples for other microorganism such as bacterial and fungal species. Here we demonstrate that higher viral load and malaria co-infection are correlated with poor patient outcome. There are a number of genes that are differentially expressed according to patient outcome – e.g. those associated with blood clotting and complement regulation. These data allowed the employment of a linear discriminant analysis which, following qRT-PCR of EBOV and three host genes, was able to predict patient outcome with exceptional accuracy. Thus suggesting that the response of survivors differs to that of fatalities during EBOV infection. The identification of potential microorganisms in the blood of EVD patients is suggestive of gut translocation of bacteria. This points towards the potential use of antibacterial agents in conjunction with treatment for EVD during outbreak settings. Potential defective interfering particles were readily detected upon sequencing of infected THP-1 cells, however, were not often found in clinical samples taken from EVD patients. These samples included those from immune-privileged niches, i.e. semen, and may suggest that Dis are not responsible for the persistence of EBOV following acute infection. This thesis highlights the fact that animal studies, cell culture and the analysis of clinical samples should be considered in tandem in order to effectively study all aspects of EBOV biology.
Efficient Synthesis of Liraglutide by Using Oxyma as Coupling Reagent

As a newly efficient reagent, Oxyma [ethyl 2-cyano-2-(hydroxyimino)acetate] has a lower rate of racemization and relative higher coupling efficiency as compared with HOBt, HOAt, etc . In this work, as an important polypeptide drug for the treatment of diabetes, liraglutide was firstly chemically synthesized with high efficiency by solid chemical synthesis using Oxyma as coupling reagent. The strategy presented here provides an efficient strategy for the chemical synthesis of liraglutide with enlarged scales.
Template-Free and Direct Electrochemical Deposition of Hierarchical Dendritic Gold Microstructures: Growth and Their Multiple Applications

Hierarchical dendritic gold microstrutures (HDGMs) with secondary and tertiary branches are directly electrodeposited on an indium tin oxide (ITO) substrate without the use of any templates, surfactants, or stabilizers. The effects of electrodeposition potential and HAuCl4 concentration on the formation of HDGMs and time-dependent morphological evolution are investigated in detail. A diffusion-limited aggregation (DLA) mechanism is used to explain the formation of HDGMs. Typically, the as-synthesized HDGMs exhibited much higher electrocatalytic activity and enhanced stability toward ethanol electrooxidation compared to bulk gold electrode and also display great Raman enhancement activity with the detection limit of 10−12 M for rhodamine 6G. The surface of HDGMs possesses hydrophobicity even without modification with low-surface-energy coatings and has a remarkable superhydrophobic property even in corrosive solutions over a wide pH range after the treatment with n-dodecanethiol. In addition, (super)oleoph.
Membranes of 5,10,15,20-Tetrakis(4-Methoxyphenyl) Porphyrinatocobalt (TMOPP-Co) (I) as MoO42- - Selective Sensors

Polyvinyl chloride (PVC) membrane electrodes based on porphyrin 5,10,15,20-tetrakis(4methoxyphenyl)porphyrinatocobalt (TMOPP-Co) (I) incorporating sodium tetra phenyl borate (NaTPB) as anion excluder and dibutyl phthalate (DBP), dioctyl phthalate (DOP), dibutyl butyl phosphonate (DBBP), tri-n-butyl phosphate (TBP), and 1-chloronaphthalene (CN) as plasticizing solvent mediators were prepared and tested for selective detection of molybdate ions. The membrane having anion excluder, NaTPB and DBP as plasticizer (membrane no. 2) proved to be best in terms of working concentration range 5.0×10-5 – 1.0×10-1M with a near – Nernstian slope of 32.0±1.0 mV/decade of activity over the pH range 5.4- 10.5. The response time of this sensor is 18s with a lifetime of about 4 months. The sensor can be used in non-aqueous medium with no significant change in the value of slope or working concentration range for the estimation of MoO42- in solutions having up to 25% (v/v) non-aqueous fraction.
Electrochemical Study of Phase Transition Processes in Lithium Insertion in V 2 O 5 Electrodes

The lithium intercalation into a V 2 O 5 substrate was studied by chronopotentiometry. The samples were prepared by atomic layer chemical vapor deposition which provides homogenous and coherent layers at the surface of titanium plates. During the charge-discharge process, various phase transitions occurred in the system Li-V 2 O 5 which induced a large change in the diffusion coefficient of lithium. To obtain an accurate analysis of the intercalation mechanism, the diffusion equation with a variable diffusion coefficient was solved by digital simulation. The thermodynamic and kinetic properties of the system are represented by an analytical model based on the complementary error function. This procedure was useful for study of the electrode behavior in a large concentration range or in a large potential domain. The influence of various parameters. such as the thickness of the sample or the thermodynamic enhancement factor, were examined.
Computer simulation of liquid/liquid interfaces. I. Theory and application to octane/water

Statistical ensembles for simulating liquid interfaces at constant pressure and/or surface tension are examined, and equations of motion for molecular dynamics are obtained by various extensions of the Andersen extended system approach. Valid ensembles include: constant normal pressure and surface area; constant tangential pressure and length normal to the interface; constant volume and surface tension; and constant normal pressure and surface tension. Simulations at 293 K and 1 atm normal pressure show consistent results with each other and with a simulation carried out at constant volume and energy. Calculated surface tensions for octane/water (61.5 dyn/cm), octane/vacuum (20.4 dyn/cm) and water/vacuum (70.2 dyn/cm) are in very good agreement with experiment (51.6, 21.7, and 72.8 dyn/cm, respectively). The practical consequences of simulating with two other approaches commonly used for isotropic systems are demonstrated on octane/water: applying equal normal and tangential pressures leads to an instabil.
Nickelocene-mediating sensor for hydrogen peroxide based on bioelectrocatalytic reduction of hydrogen peroxide

An amperometric H2O2 sensor using nickelocene as the electron transfer agent between immobilized horseradish peroxide and a glassy carbon electrode was fabricated. The sensor was highly sensitive to H2O2 with a detection limit of 5.0 × 10–7 mol l–1 H2O2 and a response time of less than 20 s. The effect of applied potential and temperature on the Michaelis–Menten constant was calculated and the influence of various experimental parameters such as pH, temperature and applied potential were explored for optimum analytical performance.
Was ist das Seltene an den Seltenen Erden?: Eine chemiedidaktische Reflexion

One of the main questions of science education is the selection of subjects, i.e.: Why do certain chemical subjects have to be taught? The answer implies the proving that the subject is scientifically relevant, has exemplifying features and is significant in every-day-life. The subject-matter „Rare Earths” does not seem to correspond to these criteria at first glance. The adjective „ rare” evokes rather opposite associations. Perhaps rare earths are rare on earth and consequently of less scientific relevance? Perhaps they have rare properties and are therefore less exemplifying? Or they are even not relevant in our every-day-life? Definitely they are rare teaching subjects. At second glance the rare earth elements do correspond to the criteria and there are good reasons for including the topic in teacher education.
Atomic Radii for Continuum Electrostatics Calculations Based on Molecular Dynamics Free Energy Simulations

The electrostatic contribution to the solvation free energy of the 20 naturally occurring amino acids is examined using atomic models. The amino acids are modeled by N-acetyl-X-N‘-methylamide. Free energy perturbation techniques with explicit water molecules are used to evaluate the contribution of solute−solvent electrostatic interactions to the solvation free energies. An analysis based on the radial solvent charge distribution yields a basic rule to determine a set of atomic Born radii defining the dielectric boundary between the solute and the solvent in continuum electrostatic models. Minor adjustments are made to refine the atomic Born radii in order to reproduce quantitatively the electrostatic contribution to the solvation free energy calculated by free energy perturbation techniques. The good agreement of continuum electrostatic and molecular dynamics free energy perturbations suggests that the new set of atomic Born radii may be used as a computationally inexpensive alternative to the microscopi.
Highly Efficient Infrared Quantum Cutting in Tb3+−Yb3+ Codoped Silicon Oxynitride for Solar Cell Applications

A high efficiency infrared quantum cutting effect in a Tb3+–Yb3+ codoped silicon oxynitride system is demonstrated. The thin films are deposited on Si substrates by reactive magnetron co‐sputtering of a Si target topped with Tb4O7 and Yb2O3 chips under pure nitrogen plasma. The photoluminescence dynamics are investigated, revealing a quantum efficiency of this system at 980 nm up to 197% for the higher Yb3+ concentration. Thus, via a cooperative transfer mechanism between Tb3+ and Yb3+, an absorbed UV–visible photon gives rise to almost two emitted IR photons. Such a down‐conversion effect is demonstrated upon indirect excitation of energy donors, via defect states in the host matrix. These down‐converter films could be directly and easily integrated on top of the Si‐based solar cell to improve the photoelectric conversion efficiency at a lower cost. An evaluation of the additional external quantum efficiency is deduced from this optical system and found to be almost 2%.
Wireless Energy transfer to long distance flying Intelligent Unmanned Aerial Vehicles (UAVs) using reactive power transfer techniques

Wireless power Transfer (WPT) to Unmanned Aerial Vehicles (UAVs) is promising to be a ground-breaking technique for efficient charging of long-distance flying UAVs. WPT allows the power to be transferred directly from a ground station to a long-distance flying UAV eliminating the need for UAVs to carry batteries as the source of power whose heavy weight affects the duration of UAV’s flight. This paper first reviews the recent application of Wireless Power Transfer to UAVs and highlights advantages of using this technique for economic and efficient design of intelligent autonomous long-distance flying UAVs. The paper then discusses the need for the fusion of the sensors used in WPT and IMU sensors used in UAVs, the use of deep learning algorithms in long distance flying UAVs, and highlights the factors that affect the safety and reliability of long distance power transfer to UAVs. The work described in this paper is part of the authors’ research project that aims to investigate and develop sustainable autonomous unmanned aerial vehicles. The progress being made so far in implementing Reactive wireless power transfer techniques (RWPT), the potential future works, and the envisaged associated challenges are reported in this paper. Keywords—Unmanned Aerial Vehicle (UAV); Wireless Power Transfer technique (WPT); Drone; Energy; Autonomous System; Sensor-fusion; Reactive wireless power transfer techniques (RWPT);
Hybrid Anion Exchange Hollow Fiber Membrane for Delivery of Ionic Drugs

Hybrid anion exchange hollow fiber membranes (HAEHFMs) based on bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) are proposed as potential drug carriers for four anionic model drugs, including the sodium salts of benzoate (NaBS), salicylate (NaSA), meta-amino salicylate (NaMAS), and loxoprofen (NaLS). The results of the static loading and release experiments suggest that electrostatic interaction, hydrogen bonding, and hydrophobic interaction are the main interaction patterns between the membrane and the drugs. And they are directly influenced by the external phase conditions and the drug physicochemical characteristics, such as structure, molecular weight, dissociation (pKa), and hydrogen bonding capability. Among the four different drugs, NaSA and NaMAS appear to be the most suitable for controlled release by the HAEHFM due to their excellent adsorption/release behaviors.
Imidazole-Promoted Synthesis of N-Substituted Phthalimide from N,N′-Disubstituted Ureas in Solventless Conditions

Abstract A series of N-substituted phthalimides was synthesized by a thermal reaction between N,N′-disubstituted ureas and phthalic acid catalyzed by imidazole in solventless conditions. The products have been obtained in moderate to good yields (53–92%). Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT
EXTRACTION OF HUMIC ACID BY ALKALI AND CHELATING RESIN

Humic acid was extracted from the A1 horizon of a Dark Chestnut soil (pH = 6.9) with 0.5 N NaOH after decalcification and with Na-Dowex A-1 resin without decalcification. The two humic acids were characterized by chemical and spectroscopic methods and by permanganate oxidation after methylation. Whereas ultimate, functional group, and infrared analyses showed the two humic acids to be very similar, permanganate oxidation indicated a number of differences between the two preparations. The yield of oxidation products from the resin-extracted humic acid was twice as high as that from the alkali-extracted material. In addition, the resin-extracted humic acid produced appreciably larger amounts of high-molecular weight phenolic and benzenecarboxylic acids than did the alkali-extracted humic acid. These findings, in conjunction with E4/E6 ratios, indicated that the chelating resin-extracted humic acid was more condensed or less degraded than that removed by alkali. Permanganate oxidation of methylated humic sub.
Review of state-of-the-art and output characteristics of table-top soft x-ray lasers

X-ray lasers (XRLs) belong to the brightest existing short-wavelength sources. The development trends are discussed from the point of view their suitability for applications. A detailed analysis of the output parameters of the XRL with transient inversion proves that this type of laser has become sufficiently mature to be applied in practice.