Miracle-dz/UniFAR-FTUs huggingface dataset:
Paste Residence Time in a Spouted Bed Dryer. I: The Stimulus-Response Methodology

The stimulus response methodology was evaluated in an experimental study conducted to measure NaCl solution residence time distributions in a spouted bed dryer of inert particles. The influence of tracer volume, concentration, and injection mode upon the measured mean residence time and residence time distribution was determined following experimental design techniques. The injection mode showed no significant effect on residence times, whereas tracer volume and concentration had significant effects at the levels of 1 and 5%, respectively, under the conditions chosen initially. The steepest ascent and factorial design methods were applied to determine the range in parameters for optimum stimulus response. The procedure repeated for a polymeric paste showed similar results. However, the results also showed that care must be exercised when using the stimulus response technique and the optimum injection conditions must be determined. The procedure presented in this study may be adopted in future investigations of paste residence time distributions in spouted bed dryers of inert bodies.
In situ Mineralization of Dairy Cattle Manures as Determined using Soil‐Surface Carbon Dioxide Fluxes

Decomposition rates of organic amendments in agricultural soils provide information on nutrient release and on changes in soil C stocks. They are usually determined using incubation of soil samples under controlled conditions. Our objective was to study decomposition of liquid and solid dairy cattle manures under field conditions following application to a loamy and a clay soil. Manures were applied in two consecutive years to silage corn at rates equivalent to 150 kg ha -1 total N providing 119 to 202 kg C ha -1 . Soil-surface CO 2 fluxes, temperature and water content were monitored weekly in manured and control (mineral fertilizer) plots. Initial decomposition rates following manure application were much slower in the first than in the second year. This lag phase was attributed to cool soil temperatures and to the time required by the soil microflora to adapt to a first addition of this exogenous organic substrate. During the first year, mineralization of manure organic C was lower in the clay (52% of manure C) than in the loamy (75%) soil, presumably as a result of less favorable aeration conditions and greater physical protection of organic substrates in the clay. Equal mineralization rates of liquid and solid manures during both years in the loamy soil indicated that the two manure types had similar decomposability. Slower decomposition of the solid than the liquid manure in the clay soil was attributed to poorer mixing with the soil (presence of clods) resulting in reduced access to the solid manure for soil decomposers. The results of this study evidenced that under field conditions manure C decomposition is not determined solely by manure characteristics but also by interactions between the manure type and soil physical properties such as texture.
Motions of an α‐helical polypeptide: Comparison of molecular and harmonic dynamics

Molecular and harmonic dynamics simulations have been performed for a decaglycine α‐helix. The extent of anharmonicity for various observables is studied by a direct comparison of the two types of simulations, at temperatures ranging from 5 to 300 K. The fluctuations of the cartesian, internal and normal mode coordinates, and their time dependence, are analyzed. The heat capacity of the α‐helix is evaluated both from the temperature response of the system to an energy perturbation and from the fluctuations in the temperature of the system. It is shown that the anharmonicity depends on the kind of observable. The root mean square atomic fluctuations have significant anharmonic components at temperatures above 100 K. In contrast, the dihedral angle fluctuations are much closer to being harmonic at all the temperatures considered. The analysis of potentials of mean force experienced by individual atoms shows that atomic displacements have approximately Gaussian distributions from 50 to 300 K, with different force constants at each temperature (quasi‐harmonic model). At 300 K, the force constants obtained by molecular dynamics are significantly lower than in the harmonic case. The time dependence of the projection of the molecular dynamics displacements on the normal mode coordinates shows that mode mixing is important above 100 K. The motions of the helix associated with the low‐frequency normal modes are described and illustrated.
Synthesis and keto-enol tautomerism of ethyl 4-oxo-3,4-dihydro-1H-pyrano[3,4-b]quinoline-3-carboxylate

An efficient method has been developed for the synthesis of a novel β-keto ester-containing pyranoquinoline compound, i.e., ethyl 4-oxo-3,4-dihydro-1H-pyrano[3,4-b]quinoline-3-carboxylate. The method entails a two-step synthesis. The first step involves the Williamson-type reaction of ethyl 2-bromomethyl-3-quinoline-3-carboxylate with ethyl hydroxyacetate in anhydrous benzene to afford the intermediate ethyl 2-[(2-ethoxy-2-oxoethoxy)methyl]quinoline-3-carboxylate. The second step includes the Dieckmann condensation reaction of the resulting intermediate in the presence of sodium ethoxide in anhydrous toluene to afford the desired pyranoquinoline containing β-keto ester moiety. Keto-enol tautomerism of the compound thus obtained was investigated by spectroscopic methods.
Using Self-Reflection To Increase Science Process Skills in the General Chemistry Laboratory

Self-reflection is a tool of instruction that has been used in the science classroom. Research has shown great promise in using video as a learning tool in the classroom. However, the integration of self-reflective practice using video in the general chemistry laboratory to help students develop process skills has not been done. Immediate video feedback and direct instruction were employed in a general chemistry laboratory course to improve students' mastery and understanding of basic and advanced process skills. Qualitative results and statistical analysis of quantitative data proved that self-reflection significantly helped students develop basic and advanced process skills, yet did not seem to influence the general understanding of the science content.
Preparation of poly(p-phenylene terephthalamide)/poly(vinyl chloride) molecular composite and its thermal and mechanical properties

Poly(p-phenylene terephthalamide) (PPTA) was blended with poly(vinyl chloride) (PVC) by solution-blending method. PPTA was metalated for dissolving in dimethyl sulfoxide. Dimethyl sulfoxide was used as a common solvent. In PPTA/PVC composite, PPTA accelerated the thermal degradation of PVC. PPTA molecules are aggregated as microfibrillar form in PVC matrix. Such microfibrils are dispersed homogeneously in PVC matrix, according to polarizing microscopic observation. The average diameter of the microfibrils becomes smaller in the composite with lower content of PPTA. In the surface region of PPTA microfibrils the intermolecular hydrogen bonds between CCl of PVC and NH of PPTA are formed. Young's modulus and the yield stress at room temperature were higher in the composites than those in PVC. The modulus of the composites was higher, especially at the high temperatures above their glass transition temperatures, than that in PVC. The temperature dependence of modulus can be calculated by using the mechanical model equivalent to the quasi-3-dimensional microfibrillar model which will be approximately applied to the composite structure. It becomes apparent that the modulus of the PPTA microfibrils evaluated by using the mechanical model is higher in the higher molecular weight PPTA.
Flame Kernel Generation and Propagation in Turbulent Partially Premixed Hydrocarbon Jet

Flame development, propagation, stability, combustion efficiency, pollution formation, and overall system efficiency are affected by the early stage of flame generation defined as flame kernel. Studying the effects of turbulence and chemistry on the flame kernel propagation is the main aim of this work for natural gas (NG) and liquid petroleum gas (LPG). In addition the minimum ignition laser energy (MILE) has been investigated for both fuels. Moreover, the flame stability maps for both fuels are also investigated and analyzed. The flame kernels are generated using Nd:YAG pulsed laser and propagated in a partially premixed turbulent jet. The flow field is measured using 2-D PIV technique. Five cases have been selected for each fuel covering different values of Reynolds number within a range of 6100–14400, at a mean equivalence ratio of 2 and a certain level of partial premixing. The MILE increases by increasing the equivalence ratio. Near stoichiometric the energy density is independent on the jet velocity while in rich conditions it increases by increasing the jet velocity. The stability curves show four distinct regions as lifted, attached, blowout, and a fourth region either an attached flame if ignition occurs near the nozzle or lifted if ignition occurs downstream. LPG flames are more stable than NG flames. This is consistent with the higher values of the laminar flame speed of LPG. The flame kernel propagation speed is affected by both turbulence and chemistry. However, at low turbulence level chemistry effects are more pronounced while at high turbulence level the turbulence becomes dominant. LPG flame kernels propagate faster than those for NG flame. In addition, flame kernel extinguished faster in LPG fuel as compared to NG fuel. The propagation speed is likely to be consistent with the local mean equivalence ratio and its corresponding laminar flame speed.
Competitive Adsorption of Nickel and Copper Ions from Aqueous Solution Using Nonliving Biomass of the Marine Brown Alga Laminaria japonica

The adsorption of nickel and copper in a bicomponent system using the nonliving biomass of the marine brown alga Laminaria japonica was investigated in batch systems as a function of initial solution pH, contact time and temperature. The adsorption of nickel and copper was strongly pH dependent. Kinetic studies pointed to a rapid uptake with an equilibrium time of about 30 min. The kinetic curves were successfully fitted by linear regression to pseudo first and pseudo-second-order equations. The equilibrium data was analyzed using several models, including the extended Langmuir equation, modified extended Langmuir model and combined extended Langmuir-Freundlich model. The results suggested that the competitive adsorption of nickel and copper at all temperatures was best represented by the combined extended Langmuir-Freundlich isotherm. The isotherms indicated competitive uptake, with copper being preferentially adsorbed followed by nickel with an increase in the amount of solute in solution. Thermodynamic analysis revealed that the simultaneous adsorption of nickel and copper ions could be considered to be a spontaneous, endothermic process, with increased randomness.
Stability and Magnetocaloric Properties of Sintered La(Fe, Mn, Si) $_{13}$ H $_{z}$ Alloys

Long-term aging treatments of partially hydrogenated ternary La-Fe-Si alloys show that these materials do not have stable magnetic properties. If partially hydrogenated LaFe13- xSixHz is held at its Curie temperature for several days it decomposes into a fraction with an increased Curie temperature and another one with decreased Curie temperature compared to the starting material. Such degrading material cannot be used in applications which require constant properties over a long period of time. By fully hydrogenating manganese containing LaFe13-x-yMnySixHz, stable alloys with adjustable Curie temperatures around room temperature can be produced. These hydrides do not change their magnetic properties if they are operated close to their Curie temperature.
In Vitro Activity and Pharmacokinetics in Patients of Cefamandole, a New Cephalosporin Antibiotic

Cefamandole nafate, a new cephalosporin for parenteral use, was evaluated in vitro against 231 recent clinical isolates and in 12 patients. Cefamandole had activity equivalent to cefazolin against Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae. Cefamandole was more active than cephalothin or cefazolin against Proteus mirabilis. Both cefamandole and cefazolin were as active as cephalothin against S. aureus, were slightly more active against K. pneumoniae, and were considerably more active against E. coli. All strains of indole-positive Proteus sp. were inhibited by 6.3 μg of cefamandole per ml but only 20% were inhibited by 25 μg of cefazolin or cephalothin per ml. Eighty-eight percent of Enterobacter sp. was inhibited by 25 μg of cefamandole per ml, but only 20 and 5% were inhibited by the same concentration of cefazolin and cephalothin, respectively. Peak levels of cefamandole ranged from 6.0 to 110 μg/ml in serum and levels ranged from 440 to 16,800 μg/ml in a 4- to 6-h collection of urine after a 500-mg or 1-g intramuscular dose (6.1 to 17.3 mg/kg) in patients with endogenous creatinine clearances of ≥31 ml/min. These levels were done after the first dose, at mid-therapy, and at the end of therapy. There was no evidence of accumulation with the 500-mg or 1-g dose given every 4 to 6 h. The percentage of the dose excreted in the urine within the first 4 to 6 h after administration of cefamandole was ≥43%. The half-life of cefamandole in serum was 49 to 126 min.
Theoretical Study on the Phase Transition and the H/D Isotope Effect of Squaric Acid

We investigated the phase transition and the isotope effect in squaric acid (H2C4O4, abbreviated H2SQ), a hydrogen-bonded dielectric material. Using first-principles calculation, we found that Jahn-Teller distortion of the unit structure (C4H4O4) was the major driving force for the phase transition in the H2SQ crystal. In order to elucidate the isotope effect on the phase transition in deuterated squaric acid (D2SQ), we employed the multi-component molecular orbital (MC_MO) method, which directly takes into account the quantum effects of protons and deuterons. Using this model, we successfully predicted the difference between the phase transition temperature of H2SQ and that of D2SQ to be 192K, which is in reasonable agreement with the experimental value of 145 K. We found that the isotope effect in the H2SQ/D2SQ system was based more on shrinking distribution of the deuteron wave rather than that of the proton wave. When the MC_MO method was coupled with adequate cluster models, first-principles calculations were effective to determining the origin of the phase transition and the H/D isotope effect in hydrogen-bonded dielectric materials.
Process Workshops--A New Model for Instruction.

In an attempt to improve student performance in chemistry courses, we adopted a new model for instruction, which we call the process workshop model. Based on a synthesis of several current ideas in learning theory and pedagogy, these workshops have produced substantial improvements in student attitudes, retention, and performance. This paper describes the characteristic features of the process workshop model, strategies for its implementation in a variety of contexts, and assessment results for courses in General Chemistry.
Fabrication and photoluminescence properties of hollow Gd2O3:Ln (Ln = Eu3+, Sm3+) spheres via a sacrificial template method

Hollow Gd2O3:Ln (Ln = Eu3+, Sm3+) microspheres were successfully fabricated by using carbon spheres as a template and urea as a precipitating agent, which involved the deposition of an inorganic coating on the surface of carbon spheres and subsequent calcination in the air. Various approaches including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence spectroscopy as well as kinetic decays were used to characterize the samples. The results indicate that the as-prepared products can be indexed to pure cubic Gd2O3 phase. The samples are composed of uniform hollow Gd2O3:Ln spheres with a mean particle size of about 300 nm. The possible mechanism of evolution from glucose to carbon microspheres and the chemical reaction of each step to form the final hollow spheres are proposed. In particular, the urea-assisted precipitation process was carried out in aqueous solution without any organic solvent, and the hollow spheres formation process was achieved by simple calcination without using any etching agents. The hollow Gd2O3:Ln phosphors exhibit light emission under ultraviolet excitation, which may find promising applications in the fields of field emission displays (FED) and MRI contrast agents.
Glass‐like structure of a lead‐based relaxor ferroelectric

It has been shown [Bosak, Chernyshov, Vakhrushev & Krisch (2012). Acta Cryst. A68, 117–123] that detailed experimental three-dimensional maps of diffuse scattering in lead-based relaxors do not agree with those expected from the concept of polar nanoregions and/or polar nanodomains. Instead, the observed diffuse scattering can be successfully parameterized in terms of a pseudo-dynamical matrix, having a shape very similar to that of the thermal diffuse scattering. Here the parameterization is extended and used to generate the disordered atomic configurations. The analysis of the resulting displacement patterns retrieved for lead ions shows that a static snapshot of the relaxor structure corresponds to the specific dipole glassy state that is characterized by local polarization and its projection onto the selected direction. The recovered structural model agrees with the observed behaviour of dielectric susceptibility as well as the existence of a wide-range hierarchy in the relaxation times in these materials.
Intra-layer ordering and inter-layer disordering of the Li2MnO3 phase in Li1.07Mn1.93O4–δ cathode materials: electron diffraction investigation and DIFFaX simulation of X-ray diffraction patterns

A previous transmission electron microscopy (TEM) analysis revealed the existence of monoclinic Li2MnO3 in the lithium-rich and oxygen-deficient Li1.07Mn1. 93O4−δ powder. Interestingly, the monoclinic phase exhibits different nanoscale lamellar variants involving a rotation of the stacking direction by 120 or 240° along the pseudo-threefold axis, i.e. the [103]M//[111]C (M and C denote the monoclinic and cubic phases, respectively) zone axis. Here, a theoretical X-ray diffraction (XRD) study of Li2MnO3 employing the DIFFaX program is presented. It is found that, with the occurrence of different stacking configurations, the characteristic superstructure reflections with 2θ between 20 and 35° (Cu Kα) in the XRD pattern become more and more broadened with the increasing degree of stacking disorder, indicating that XRD may fall short in detecting the presence of the monoclinic Li2MnO3 phase. Moreover, selective peak asymmetry appears when the stacking sequence becomes extremely disordered. Further selected-area electron diffraction and theoretical neutron diffraction investigation may clarify the similar ambiguity concerning the crystal phases of other structurally related compound cathode materials for lithium-ion batteries (e.g. LiNi1/2Mn1/2O2, LiNi1/3Co1/3Mn1/3O2).
Flammability and the Heat of Combustion of Natural Fuels: A Review

Heat of combustion (HoC) is a key characteristic of fuels when analyzing and modeling wildfire scenarios. Despite significant differences in the structure of fuels from different environments, HoC is frequently considered a constant. This article briefly reviews methods used to describe natural fuels and the various different definitions of HoC. We also summarize measured values of HoC and elemental analyses of 238 plant genera reported in 28 papers since 1973. A statistical analysis of these data provided mean values and standard deviations of HoC for fuels according to six broad plant functional groups. Permutational Multivariate Analysis of Variance (PERMANOVA) demonstrated significant differences in the HoC with ground fuels and softwoods having particularly high values. Net heat of combustion was calculated for four fuel groups and the tabulated data may help to improve wildfire modeling and highlights fuels where further measurements of HoC are required.
Influence of aging, thermal, hydrothermal, and mechanical treatments on the porosity of MCM-41 mesoporous silica

A mesoporous siliceous material of MCM-41 type was characterized by nitrogen adsorption, X-ray diffraction, and Fourier transform infrared spectroscopy. Its pore diameter, external and internal surface, pore volume, wall thickness, and pore wall density were determined. Special attention was paid to sample aging and its stability toward temperature, water vapor, and mechanical compression, aiming at using this material in industrial applications such as adsorption or catalysis. Calcined MCM-41 loses an important part of its mesoporosity during aging under ambient temperature, pressure, and humidity conditions but then becomes stable after 3 months, still retaining a noticeable porosity. The aged MCM-41 can withstand temperatures up to 873 K and uniaxial compressions up to 100 MPa without too much damage. After contact with water vapor at 358 K, the porous structure was totally destroyed and an amorphous phase was obtained.
Removal of chlorinated solvents from carbonate-buffered water by zero-valent iron

The performance of a ground level reactive cell, filled with Fe0, designed for the treatment of water contaminated by chlorinated solvents, having a total input concentration of approximately 2 mg 1−1 of the principal contaminants trichloroethene and perchloroethene, was tested at the Milovice site in the Czech Republic. A residence time of 1.62 days in the box was sufficient to reduce concentrations to a fraction less than 0.015 of the initial concentration. However, incomplete degradation of cis-1,2-DCE was observed. Reactions approximated first-order kinetics. The principal changes of concentrations of inorganic dissolved species in the reactive cell occurred for Ca2+, HCO3−, NO3− (decreased) and for Fe (initially increased, then decreased). Changes for Ca2+ and HCO3− were caused by the precipitation of secondary carbonate mineral phases such as aragonite and siderite with the minor presence of green rust-CO3. Concentration changes were gradual, along the complete length of the cell with a maximum at the inlet zone. The observations were attributed to minor increases of pH and slow kinetics of precipitation in the carbonate-buffered system. The average porosity loss was estimated to be approximately 2.7 % of the initial porosity per year, suggesting the long-term function of the permeable reactive barrier.
OFF-DIAGONAL HYPERVIRIAL THEOREM AND ITS APPLICATIONS

A hypervirial operator, by definition, is a time‐independent linear operator with an arbitrary functional structure expressed in terms of the dynamical variables of the system under consideration. In the energy representation, the diagonal matrix elements of the hypervirial operator are constant in time; this is known as the hypervirial theorem. The off‐diagonal matrix elements of the hypervirial operator in the energy representation oscillate in time with frequencies related to the energy differences between their corresponding stationary states of the system. This is known as the off‐diagonal hypervirial theorem.The latter theorem is as powerful as the former for dealing with many quantum‐mechanical problems. Several aspects of the possible applications of the theorem to the problem of construction and improvement of wavefunctions are considered. As a special example, the restricted fourth alternative expression for dipole transition matrix elements is derived for pair functions not belonging to states .