Miracle-dz/UniFAR-FTUs huggingface dataset:
A rheological evaluation of linear and branched controlled-rheology polypropylenes

Commodity linear and branched polypropylene resins have been modified by means of peroxide initiated chemical degradation in a reactive extrusion process. Data collected from molar mass and linear viscoelastic property measurements have been used to evaluate the L“crossover modulus” and “modulus separation” rheological polydispersity measures and a theoretical justification is provided for the modulus separation index. In the past, these empirical methods have been used successfully to relate molar mass characteristics to rheological properties. Results obtained in this study confirm the validity of the modulus separation index for linear polymers and suggest that it should be used carefully in the analysis of data from branched polymers. Linear viscoelastic data are used to estimate the terminal relaxation time spectra of both the linear and branched materials and a new correlation between modulus separation and relaxation time polydispersity is given. Des resines de commodite de polypropylene 1ineaires EC ramifiees ont ete rnodifiees par degradation chimique au peroxyde dans un procede d'extrusion reactive. Des donnees venant de mesures des proprietes viscoelastiques lineaires et de masse molaire ont ete utilisees pour evaluer les mesures rheologiques de polydispersite de “module de croisement”' et de “separation des modules”, et une justification theorique est donnee pour l'indice de separation des modules. Dans le passe, ces methodes empiriques ont ete utilisees avec succes pour relier les caracteristiques de masse molaire aux proprietes rheologiques. Les resultats obtenus dans cette etude confirment la validite de l'indice de separation des modules pour les polymeres lineaires et suggerent qu'on devrait les utiliser avec prudence dans l'analyse des donnees de polymeres ramifies. On utilise des donnees viscoelastiques Iineaires pour estimer le spectre de temps de relaxation terminal des rnateriaux 1ineaires et rarnifies, et on donne une nouvelle correlation entre la separation des modules et la polydispersite de temps de relaxation.
The shifted reflective boundary for the study of two-phase systems with molecular dynamics simulations

When studying fluids with molecular dynamics simulations, periodic boundaries are usually used to model the infinite bulk fluid surrounding the primary cell. For homogeneous systems this is, as a rule, the most appropriate way. For inhomogeneous systems, e.g. systems with a fluid–vapour interface, periodic boundaries have some disadvantages. Therefore, an alternative for periodic boundaries, called the shifted reflective boundary, is proposed for modelling such systems. From a computational point of view, this type of boundary is no more difficult to implement than periodic boundaries. It is shown that the shifted reflective boundary results in a stable spatial fluid–vapour configuration with one fluid–vapour interface, while retrieving the same numerical results for the thermodynamic properties, e.g. the surface tension, as molecular dynamics simulations with periodic boundaries. Molecular dynamics simulations with shifted reflective boundaries also need fewer particles than corresponding simulations with periodic boundaries.
The n‐Silicon/Thallium(III) Oxide Heterojunction Photoelectrochemical Solar Cell

Thallium(III) oxide is a degenerate n-type semiconductor which can be electrochemically or photoelectrochemically deposited on conducting or semiconducting substrates. The material is highly conductive, transparent, and electrocatalytic. A photoelectrochemical cell consisting of the n-silicon/thallium(III) oxide photoanode and a platinum cathode in an alkaline solution of the ferrocyanide/ferricyanide redox couple produced a 0.512V open-circuit photovoltage, 33.5 mA/cm/sup 2/ short-circuit photocurrent density, 0.643 fill factor, and 13.8, photovoltaic efficiency with 80 mW/cm/sup 2/ iR-filtered xenon light. The efficiency was 11.0% with 75.3 mW/cm/sup 2/ natural sunlight, and 22.3% with 800 nm monochromatic light. The short-circuit quantum efficiency at 800 nm was 97%. A xenon photovoltaic efficiency of 10.2% was observed with cast multicrystalline n-silicon. Photocurrent-voltage curves were computer simulated using values of the barrier height (0.96V), diode quality factor (1.2), and series resistance (200.cap omega.) that were measured from dark current voltage and capacitance-voltage curves. A solid-state photovoltaic cell was fabricated by making a low-pressure point contact to the front surface of a dry photoanode. The photovoltaic characteristics of the solid-state cell were nearly identical with those of the photoelectrochemical cell. These results suggest that the photoelectrochemical cell functions like a Schottky-barrier or SIS solid-state photovoltaic cell in series with a highlymore » reversible electrochemical cell. « less
Modified Calcite Deposition Due to Ultrathin Organic Films on Silicon Substrates

In order to study the effect of organic surface chemistry on calcite nucleation, attachment, and growth, calcium carbonate was precipitated in the presence of various ultrathin-film organosilane-modified silicon wafers. The chemistry of the aminosilane surfaces was systematically changed by the coupling of various acidic molecules, without creating a geometric lattice of acidic functional groups. Optical microscopy, scanning electron microscopy with image analysis, and X-ray scattering were employed to characterize crystallite density and orientation normal to the surface. Calcite grown on amino-modified surfaces was produced with the equilibrium rhombohedral habit and had the 〈104〉 orientation. Surfaces of the silicon oxide, carboxylate, iminodiacetate, or phosphoramidate tended to favor the orientation of surface crystals along 〈001〉 or near the 〈001〉 axes of the crystal. Primarily this is a result of the affinity of the surface for cations, but functional-group-mediated ion ordering and/or stereochemic.
2D-Ising-like critical behavior in mixtures of water and 3-methylpyridine including antagonistic salt or ionic surfactant

The effect of an antagonistic salt on the phase behavior and nanoscale structure of a mixture of D2O and 3-methylpyridine was investigated by visual inspection and small-angle neutron scattering (SANS). The addition of the antagonistic salt, namely sodium tetraphenylborate (NaBPh4), induces the shrinking of the two-phase region in contrast to the case in which a normal (hydrophilic) salt is added. Below the phase separation point, the SANS profiles cannot be described by the Ornstein–Zernike function owing to the existence of a long-range periodic structure. With increasing salt concentration, the critical exponents change from the values of 3D-Ising and approach those of 2D-Ising. These results suggest that the concentration fluctuation of the mixture of solvents is limited to a quasi two-dimensional space by the periodic structure induced by the adding the salt. The same behaviors were also observed in mixtures composed of water, 3-methylpyridine, and ionic surfactant.
Nanotoxicity: Dimensional and Morphological Concerns

Nanotechnology deals with the construction of new materials, devices, and different technological systems with a wide range of potential applications at the atomic and molecular level. Nanomaterials have attracted great attention for numerous applications in chemical, biological, and industrial world because of their fascinating physicochemical properties. Nanomaterials and nanodevices are being produced intentionally, unintentionally, and manufactured or engineered by different methods and released into the environment without any safety test. Nantoxicity has become the subject of concern in nanoscience and nanotechnology because of the increasing toxic effects of nanomaterials on the living organisms. Nanomaterials can move freely as compared to the large-sized particles; therefore, they can be more toxic than bulky materials. This review article delineates the toxic effects of different types of nanomaterials on the living organisms through different sources, like water, air, contact with skin, and the methods of determinations of these toxic effects.
Four New Compounds from the Australian Brown Alga Cystophora brownii

Two new steroids, (20S)-3β,20-dihydroxyergosta-5,24(28)-dien-16-one (7) and 3β-hydroxyergosta-5,24(28)-dien-16-one (9), and two new diastereoisomeric meroditerpenes, compounds (10) and (11), † have been isolated from the brown alga Cystophora brownii (Cystoseiraceae). Their structures were elucidated by one- and two-dimensional n.m. r. and other spectrometric and chemical methods.
Towards Complex Matter: Supramolecular Chemistry and Self-organization*

Chemistry has developed from molecular chemistry, mastering the combination and recombination of atoms into increasingly complex molecules, to supramolecular chemistry, harnessing intermolecular forces for the generation of informed supramolecular systems and processes through the implementation of molecular information carried by electromagnetic interactions. Supramolecular chemistry is actively exploring systems undergoing self-organization, i.e. systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components, on the basis of the molecular information stored in the covalent framework of the components and read out at the supramolecular level through specific molecular recognition interactional algorithms, thus behaving as programmed chemical systems. Supramolecular entities as well as molecules containing reversible bonds are able to undergo a continuous change in constitution by reorganization and exchange of building blocks. This capability defines a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels. CDC introduces a paradigm shift with respect to constitutionally static chemistry. It takes advantage of dynamic constitutional diversity to allow variation and selection and thus adaptation. The merging of the features of supramolecular systems – information and programmability; dynamics and reversibility; constitution and structural diversity – points towards the emergence of adaptive chemistry. A further development will concern the inclusion of the arrow of time, i.e. of non-equilibrium, irreversible processes and the exploration of the frontiers of chemical evolution towards the establishment of evolutive chemistry, where the features acquired by adaptation are conserved and transmitted. In combination with the corresponding fields of physics and biology, chemistry thus plays a major role in the progressive elaboration of a science of informed, organized, evolutive matter, a science of complex matter.
On the soil information content of visible–near infrared reflectance spectra

We describe the information content of soil visible–near infrared (vis–NIR) reflectance spectra and map their spatial distribution across Australia. The spectra of 4030 surface soil samples from across the country were measured with a vis–NIR spectrometer in the range 350 to 2500 nm. The spectra were compressed by a principal component analysis (PCA) and the resulting scores were mapped by ordinary point kriging. The largely dominant and common feature in the maps was the difference between the more expansive, older and more weathered landscapes in the centre and west of Australia and the generally younger, more complex landscapes in the east. A surface soil class map derived from the clustering of the principal components was similar to an existing soil classification map. We show that vis–NIR reflectance spectra (i) provide a rapid and efficient integrative measure of the composition of the soil, (ii) can replace the use of traditional soil properties to describe the soil and make pedological interpretations of its spatial distribution and (iii) can be used to classify soil objectively.
Magnetic viscosity in different Nd‐Fe‐B magnets

Measurements of magnetic viscosity in Nd‐Fe‐B magnets of different kinds (sintered magnets, MQII magnets prepared from ribbons, and LDC magnets prepared by liquid dynamic compaction) are reported. In all magnets, the viscosity S and the irreversible susceptibility χirr are found to be proportional. The temperature dependence of the coefficient Sv =S/χirr exhibits a sharp maximum at about 100 K. The temperature dependence of the activation energy E0 which governs magnetic aftereffects is deduced from these data. In sintered and LDC magnets, but not in MQII ones, E0 is found to be approximately proportional to the domain wall energy. It is concluded that the mechanism of coercivity is different in sintered and LDC magnets than in the MQII ones.
Fabrication of Aluminum Bipolar Plates by Semi‐solid Forging Process and Performance Test of TiN Coated Aluminum Bipolar Plates

Aluminum bipolar plates that can replace graphite bipolar plates for PEM fuel cells are made by applying a semi‐solid forging process. A semi‐solid slurry is made using electromagnetic stirring (EMS), and the resulting slurry is injected into a forging die attached to a 200 ton hydraulic press. The slurry is then compressed with a punch, flowed into a die cavity, and solidified into the bipolar plate form. A356 (cast Al alloy), A6061 (wrought Al alloy), and A1100 (pure Al) are used to make the plates. Titanium nitride (TiN) coating is deposited on the aluminum bipolar plates. An atomic force microscope (AFM) is used to measure the surface roughness of the plates. TiN coated A356 and A1100 plates have a surface roughness of Ra < 1.2 μm. The plate thickness is 1.2 mm. The active area of the channel is 70 mm × 70 mm, with a depth and width of 0.3 and 1.0 mm, respectively. The three TiN‐coated aluminum plates are combined with a unit cell for a performance test. Our results show that a current density value of 473 mA cm–2 (about 41% of the current density value of commercial graphite plates) can be obtained.
Interaction of Sulfur Dioxide, Polyphenols, and Oxygen in a Wine-Model System: Central Role of Iron and Copper

The rate of oxidation of SO2 was studied in a wine-model system under aerial oxygen saturation conditions to gain further insight into its mechanism of action in wine. When SO2 was studied alone, no significant oxidation was observed unless iron and copper were introduced. When these metals were added a slow oxidation was observed and bound SO2 also increased to a small but significant extent. These results are consistent with a radical chain mechanism initiated by metal catalysis, in which powerful oxidizing radicals, capable of oxidizing ethanol to acetaldehyde, are produced. This increase in bound SO2 is prevented by 4-methylcatechol (4-MeC) in keeping with the known ability of polyphenols to scavenge these intermediate radicals and thus to inhibit SO2 autoxidation, which consequently should not occur in wine. When 4-MeC was introduced at a concentration that simulated the reducing capacity of red wine, again no significant SO2 oxidation was observed without addition of iron and copper. Had the catechol been oxidized, hydrogen peroxide would have been generated and reacted with the SO2. In the presence of both metals the rate of SO2 oxidation was markedly increased compared to SO2 alone and then was dependent on the concentration of the catechol. These results demonstrate the crucial importance of metals in allowing polyphenol oxidation and that the rate of SO2 consumption is dependent on the rate of catechol oxidation. When iron and copper were added separately, only a modest increase in rate of catechol oxidation resulted. However, when combined, marked synergism was observed and the rate then became very sensitive to copper concentration. It is proposed that copper, by interacting with oxygen, facilitates redox cycling of iron. Exposure of a red wine to the conditions used in this study produced similar results regarding SO2 oxidation to those observed.
THERMODYNAMICS OF MOISTURE SORPTION IN ALFALFA PELLETS

ABSTRACT Experimental data on sorption isotherms of alfalfa pellets were used to determine the thermodynamic functions (differential heat of sorption, spreading pressure, net integral enthalpy and entropy) of the pellets. The thermodynamic functions were then utilized in modeling the specific heats of pellets as a function of moisture content. The estimated values of the thermodynamic functions at different moisture contents confirmed the results of an earlier study on the influence of moisture sorption on the physical integrity of the pellets. The changes in the thermodynamic properties and physical integrity were prominent when the moisture of the pellets were between 0.10 and 0.12 (mass fraction basis). Using the differential heat of sorption, it was determined that alfalfa pellets have higher affinity for moisture uptake when compared to wheat and lentils. The specific heat of the solids of alfalfa pellets had a parabolic relationship with moisture whereas the specific heat of water fraction increased.
Evaluation of browning rate of quince at ambient exposure

Since quince is a fruit relatively susceptible to browning, in the present work it was evaluated the colour of the quince over time of exposure to the atmospheric air. The colour of the fresh pulp was assessed using a handheld tristimulus colorimeter using the CIELab colour coordinates: L*a*b*. These Cartesian coordinates were then used to calculate the polar or cylindrical coordinates: value, hue angle (o) and chroma. At each instant, ten measurements of colour were made, and to evaluate the colour change, measurements were repeated in the same samples after every 5 minutes, over a period of two hours. The results obtained for the medium values of the cylindrical coordinates in the freshly cut quince were found to be: value = 7.80, chroma = 31.78 and Hue = 92.28o, being these values determined right after cutting. Total colour difference (TCD) was calculated having the values of the Cartesian coordinates of the freshly cut quince as reference. In relation to the colour change, the values for TCD were 0.00, 26.35, 30.41, 31.81 and 32.39, respectively for times 0, 30, 60, 90 and 120 minutes, indicating a faster rate initially and a tendency for stabilization towards the end of the period analyzed.
Life on the edge: the plankton and chemistry of Beaver Lake, an ultra‐oligotrophic epishelf lake, Antarctica

1. Beaver Lake, a large epishelf lake in eastern Antarctica was sampled on two occasions during the austral summer of 2000. Two sites, one 1 km offshore and another 6 km offshore were sampled at intervals to depths of 40 and 110 m, respectively. 2. The lake is an end member of ultra-oligotrophic lake systems with a very low carbon pool. Dissolved organic carbon concentrations ranged between 95 and 652 lg L±1. Nutrient levels were generally low with soluble reactive phosphorus ranging from undetectable to 8.4 lg L±1, ammonium ranged between 1.8 and 5.0 lg L±1, nitrate from undetectable to 161 lg L±1 and nitrite 1.1±5.3 lg L±1. 3. Chlorophyll a concentrations (0.39±4.38 lg L±1) showed an unusual distribution with the highest levels close to the lake bottom at the offshore site (110 m) where the phototrophic nano¯agellates (PNAN) displayed strong auto¯uorescence. 4. Bacterial concentrations were low, with a maximum of 7.60 ´ 107 L±1, as were the concentrations of heterotrophic nano¯agellates that exploit them. 5. Primary production ranged between 19.7 and 25.49 lg C L±1 day±1 and bacterial production from 0.32 to 1.15 lg C L±1 day±1. 6. In common with other continental Antarctic lakes, the system was dominated by a microbial plankton. However, a dwarf variety of the calanoid copepod, Boeckella poppei, occurred below 25 m at concentrations of 3±5 L±1. 7. The data suggest that primary production and bacterial production were not limited by nutrient availability, but by other factors, e.g. in the case of bacterial production by organic carbon concentrations and primary production by low temperatures.
A Fractional Order Dengue Fever Model in theContext of Protected Travellers

Climate changes are affecting the control of many vector-borne diseases, particularly in Africa. In this work, a dengue fever model with protected travellers is formulated. CaputoFabrizio operator is utilized to obtain some qualitative information about the disease. The basic properties and the reproduction number is studied. The two steady states are determined and the local stability of the states are found to be asymptotically stable. The fixed pointed theory is made use to obtain the existence and uniqueness of solutions of the model. The numerical simulation suggests that the fractional-order affects the dynamics of dengue fever.
Addressing educational inequalities and promoting learning through studies of stress physiology in elementary school students

Abstract To be ready to learn, children need to be focused, engaged, and able to bounce back from setbacks. However, many children come to school with heightened or diminished physiological arousal due to exposure to poverty-related risks. While stress physiology plays a role in explaining how adversity relates to processes that support students’ cognitive development, there is a lack of studies of physiological stress response in educational settings. This review integrates relevant studies and offers future directions for research on the role of stress physiology in the school adaptation of elementary school students, focusing on these important questions: (a) What are the links between physiological stress response and learning-related skills and behaviors, and do they vary as a function of proximal and distal experiences outside of school? (b) How are school experiences associated with students’ physiological stress response and related cognitive and behavioral adaptations? (c) How can we leverage measures of students’ physiological stress response in evaluations of school-based interventions to better support the school success of every student? We hope to stimulate a new wave of research that will advance the science of developmental stress physiology, as well as improve the application of these findings in educational policy and practice.
Simultaneous measurements of deforming Hinze-scale bubbles with surrounding turbulence

Abstract We experimentally investigate the breakup mechanisms and probability of Hinze-scale bubbles in turbulence. The Hinze scale is defined as the critical bubble size based on the critical mean Weber number, across which the bubble breakup probability was believed to have an abrupt transition from being dominated by turbulence stresses to being suppressed completely by the surface tension. In this work, to quantify the breakup probability of bubbles with sizes close to the Hinze scale and to examine different breakup mechanisms, both bubbles and their surrounding tracer particles were simultaneously tracked. From the experimental results, two Weber numbers, one calculated from the slip velocity between the two phases and the other acquired from local velocity gradients, are separated and fitted with models that can be linked back to turbulence characteristics. Moreover, we also provide an empirical model to link bubble deformation to the two Weber numbers by extending the relationship obtained from potential flow theory. The proposed relationship between bubble aspect ratio and the Weber numbers seems to work consistently well for a range of bubble sizes. Furthermore, the time traces of bubble aspect ratio and the two Weber numbers are connected using the linear forced oscillator model. Finally, having access to the distributions of these two Weber numbers provides a unique way to extract the breakup probability of bubbles with sizes close to the Hinze scale.