Miracle-dz/UniFAR-FTUs huggingface dataset:
Towards rationalising collapse times for the delayed sedimentation of weakly-aggregated colloidal gels

By delayed sedimentation is meant the rapid collapse of a colloidal gel following a period of either little or no sedimentation. The delay or collapse time can range from seconds to many months, depending upon the strength of the gel. Delayed collapse is generally presumed to be a consequence of steady coarsening which somehow brings the gel to a critical state. Earlier work on very weak depletion gels demonstrated an exponential dependence of the collapse time on depletant concentration, implying that the activation energy for coarsening is equal to the mean binding energy of the particles, θ. This correlation is not however followed by the somewhat stronger secondary-minimum gels studied originally by Partridge, who first reported the phenomenon of delayed collapse. It is demonstrated here that the scaling on the mean binding energy becomes progressively more and more sub-Arrhenius as the latter is increased above ca. 10 kBT, also that the width of the potential well has an important effect. Between them, these two effects account for the faster than expected collapse shown by the secondary-minimum gels and by more strongly-flocculated depletion gels. It is suggested that apparent departures from Arrhenius scaling are a consequence of heterogeneity which causes the mean activation energy and the mean binding energy to differ as the energies become larger.
A theory for fast‐igniting catalytic converters

Using asymptotic expansion and numerical analysis, the authors demonstrate how the step-response ignition time of an automobile catalytic converter depends on the ratio of the reaction rate to the interphase heat-transfer rate, as measured by a key Damkoehler parameter X and the degree of monolith subcooling n. In the region of low reaction rate at small X, the normalized ignition time t scaled by the homogeneous ignition time t{sup {infinity}} from the inlet gas temperature is (t/t{sup {infinity}}) = 1 + 2X{sup 1/2}{vert_bar}ln(X{sup 1/2}/2n){vert_bar}{sup 1/2}, and the ignition takes place at a thermal front deep in the monolith. At large X when the reaction rate is high, ignition occurs at the leading edge of the monolith with (t/t{sup {infinity}}) = 2.50 + X(ln n {minus} 0.34). The delay in ignition time with increasing X is due to a Taylor-Aris dispersion mechanism induced by interphase heat transfer. Although the small-X ignition mechanism is faster, its downstream ignition location leads to a very slow upstream propagation of the thermal front that follows ignition. An optimal converter system that ignites in 13 s, 25% of the current value in a standard step-response test, is then designed by placing a small igniter, which ignitesmore » by the small-X mechanism, upstream to preheat the current converter which then ignites by the large-X mechanism. The length of the igniter is kept small by bypassing 2/3 of the exhaust since, from the authors` theory, t{sup {infinity}} is independent of the gas velocity. « less
Positronium formation in a liquid phase: Influence of intratrack reactions and temperature

This work clarifies some discrepancies between conventional models, used in positron annihilation lifetime (PAL) spectroscopy, and experimental data. The importance of taking into account Ps interactions with primary intratrack radiolytic products is demonstrated, for example, for PAL data in water. We examine the applicability of a nonhomogeneous chemical kinetics approach and of a well-known expression for the reaction rate constants to describe intratrack processes, and show that the prescribed diffusion approximation (PDA) is a reasonable model for this. Moreover, we have derived an analytical expression for the time-dependent reaction rate coefficient, which previously entered PDA as an external parameter. Preliminary fittings of the PAL spectra in H2O over a wide temperature range indicate that Ps reactions in intratrack processes are diffusion controlled (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Peer-to-Peer Sharing of Social Media Messages on Sexual Health in a School-Based Intervention: Opportunities and Challenges Identified in the STASH Feasibility Trial

Background There is a strong interest in the use of social media to spread positive sexual health messages through social networks of young people. However, research suggests that this potential may be limited by a reluctance to be visibly associated with sexual health content on the web or social media and by the lack of trust in the veracity of peer sources. Objective The aim of this study was to investigate opportunities and challenges of using social media to facilitate peer-to-peer sharing of sexual health messages within the context of STASH (Sexually Transmitted Infections and Sexual Health), a secondary school-based and peer-led sexual health intervention. Methods Following training, and as a part of their role, student-nominated peer supporters (aged 14-16 years) invited school friends to trainer-monitored, private Facebook groups. Peer supporters posted curated educational sex and relationship content within these groups. Data came from a feasibility study of the STASH intervention in 6 UK schools. To understand student experiences of the social media component, we used data from 11 semistructured paired and group interviews with peer supporters and their friends (collectively termed students; n=42, aged 14-16 years), a web-based postintervention questionnaire administered to peer supporters (n=88), and baseline and follow-up questionnaires administered to students in the intervention year group (n=680 and n=603, respectively). We carried out a thematic analysis of qualitative data and a descriptive analysis of quantitative data. Results Message sharing by peer supporters was hindered by variable engagement with Facebook. The trainer-monitored and private Facebook groups were acceptable to student members (peer supporters and their friends) and reassuring to peer supporters but led to engagement that ran parallel to—rather than embedded in—their routine social media use. The offline context of a school-based intervention helped legitimate and augment Facebook posts; however, even where friends were receptive to STASH messages, they did not necessarily engage visibly on social media. Preferences for content design varied; however, humor, color, and text brevity were important. Preferences for social media versus offline message sharing varied. Conclusions Invitation-only social media groups formed around peer supporters’ existing friendship networks hold potential for diffusing messages in peer-based sexual health interventions. Ideally, interactive opportunities should not be limited to single social media platforms and should run alongside offline conversations. There are tensions between offering young people autonomy to engage flexibly and authentically and the need for adult oversight of activities for information accuracy and safeguarding.
Formulation and Copping Temperature Effects on Beef Frankfurters

Frankfurters were manufactured using four fat and added water (AW) formulations (10% fat/30% AW; 15%/25%; 20%/20%; 30%/10%) and processed at chopping temperatures 9, 12, or 15°C. The batters were stuffed into cellulose casings, thermally processed, chilled and vacuum-packaged. Frankfurters were analyzed for proximate composition, textural properties and purge. No differences occurred among treatments for processing yield (89.8%± 1.83). Frankfurters chopped to 12°C had the highest (P < 0.05) Kramer peak force values. As expected, purge increased in all treatments as storage time increased (P < 0.05). As AW increased, hardness and cohesiveness decreased and purge increased. Water level and fat reduction were the most critical factors affecting quality.
What do we play? Influence of the Small-Sided and Conditioned Games to improve the students’ physiological and physical performance

variables fisiológicas Abstract Introduction: the small-sided and conditioned games (SSCGs) are an ideal tool for overcome a decontextualized Physical Education (PE) sport practice. Aim: the main purpose of this research was to quantify and compare the physiological and physical performance from a SSCG 3vs.3, a SSCG 4vs.4 and a technical analytical drill through the global indicator Edwards’ TRIMP, the response perceived-exertion (RPE) and the total distance covered. The secondary objective was to analyze the relationship between the mentioned physiological and physical variables. Methods: a quantitative, quasi-experimental and cross-sectional study was carried out on a sample of 80 students from third to sixth grade in Elementary Education (9.61±1.15 years old). Technology Polar Team Pro™ and the Response Perceived -Exertion have been used to quantify both physiological and physical variables. Results & discussion: results establish significant differences at 3vs.3 and 4vs.4 SSCGs against the drills (p<0.001). Moreover, it was also observed significant differences at 3vs.3 in contrast to 4vs.4 SSGs (p<0.001), and a significant positive correlation was observed among the loads of the games and drills. Conclusions: the SSCGs in PE supposed useful tools designed to improve the physiological and physical performance as well as promoting healthy habits in contrast to a more decontextualized practice based on technical task exclusively. For that reason, it is recommended, on the one hand, to implement SSCGs at the lessons plans and, on the other hand, to use tools such as the RPE to control the students’ physiological and physical variables.
Interactive effects of binary combinations of manganese with other heavy metals on metal uptake and antioxidative enzymes in Brassica juncea L. seedlings

Abstract The present study investigates the interactive mechanism involved during the uptake of heavy metals and stress tolerance in Brassica juncea L. seedlings under the influence of Mn(II) in binary combinations with Cr(VI), Ni(II), Co(II) and Cu(II) in terms of changes in antioxidative enzymes-superoxide dismutase (SOD), guaiacol peroxidase (GPX), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). The order of uptake of heavy metals by the seedlings in single metal solutions was observed to be, Mn>Cu>Co>Cr>Ni. As revealed by multiple regression and path analysis, manganese (Mn) in binary combination with other heavy metals mutually decreased the uptake of each other. Mn and other metals were antagonistic to each other for the activities of SOD, GPX, APX and GR, and decreased the effect of each other through interaction, whereas antagonism between these metals increased the activity of CAT.
Rate constants for the reactions of methylvinyl ketone, methacrolein, methacrylic acid, and acrylic acid with ozone

Rate constants for the reaction of ozone with methylvinyl ketone (H2C(DOUBLEBOND)CHC(O)CH3), methacrolein (H2C(DOUBLEBOND)C(CH3)CHO), methacrylic acid (H2C(DOUBLEBOND)C(CH3)C(O)OH), and acrylic acid (H2C(DOUBLEBOND)CHC(O)OH) were measured at room temperature (296±2 K) in the presence of a sufficient amount of cyclohexane to scavenge OH-radicals. Results from pseudo-first-order experiments in the presence of excess ozone were found not to be consistent with relative rate measurements. It appeared that the formation of the so-called Criegee-intermediates leads to an enhanced decrease in the concentration of the two organic acids investigated. It is shown that the presence of formic acid, which is known to react efficiently with Criegee-intermediates, diminishes the observed removal rate of the organic acids. The rate constant for the reaction of ozone with the unsaturated carbonyl compounds methylvinyl ketone and methacrolein was found not to be influenced by the addition of formic acid. Rate constants for the reaction of ozone determined in the presence of excess formic acid are (in cm3 molecule−1 s−1): methylvinyl ketone (5.4±0.6)×10−18; methacrolein (1.3±0.14)×10−18; methacrylic acid (4.1±0.4)×10−18; and acrylic acid (0.65±0.13)×10−18. Results are found to be consistent with the Criegee mechanism of the gas-phase ozonolysis. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 769–776, 1998
Methane Oxidation in Simulated Landfill Cover Soil Environments

Methane is an important greenhouse gas. Its contribution to the enhanced global warming is estimated at 12%. A considerable fraction of the methane that is produced by landfills is oxidized by its covering soil before it can reach the atmosphere. This process was studied in soil columns that simulate landfill cover soil environments. The methane uptake was followed as a function of time. In soils of agricultural origin, a maximum value of 10.7 mol m{sup {minus}2}{sub column} d{sup {minus}1} was observed. Mixing sugar beet leaves with the soil led to a temporary stimulation of the methane oxidation rate, whereas a wheat straw amendment led to permanent stimulation. Soil originating from a real landfill cover oxidized on the order of 15 mol m{sup {minus}2}{sub column} d{sup {minus}1}, the highest value found in the literature to date. The soil gas composition was studied as a function of depth. With a new batch incubation technique, methane oxidation kinetics were determined in samples taken from the soil column. By combining this kinetic data with the soil gas composition data, the actively methane oxidizing zone in the soil column could be determined and an in situ assessment of oxygen limitation could be performed. Methane oxidationmore » takes place mainly in the top 30 cm of the covering soil. « less
PENETRATION OF SOLAR UV IRRADIATION IN COASTAL LAGOONS OF THE SOUTHERN BALTIC SEA AND ITS EFFECT ON PHYTOPLANKTON COMMUNITIES

Abstract Direct measurements of solar UV irradiance at the surface and in the water column were made in several coastal lagoons near the islands of Hiddensee and Rügen in spring and summer 1993 using an internally frosted quartz sphere at the end of a 10 m quartz fiber cable connected to a double monochromator spectroradiometer. The measurements showed a nearly uniform vertical distribution of the absorption coefficient in the whole water column due to effective mixing, shallow depths and little temperature and salinity density stratifications. There was an increase in the absorption coefficient at 310 nm from 5 m−1 in the outer lagoons to 12 m−1 in the open inner lagoons and up to 29 m−1 in the inner lagoons without water exchange with the Baltic Sea as a result of different amounts of UV‐absorbing substances such as yellow substance (Gelbstoff) and seston. Depending on the specific concentration of the absorbents, the solar UV‐B irradiance decreases to 1% after penetration into the water column between 0.2 m (inner lagoons without water exchange), 0.4 m (inner lagoons with water exchange), and 1 m (outer lagoons), whereas UV‐A penetrates on the order of several meters. As phytoplankton populates the top layers of the water column it may be affected by increased solar UV irradiation even in these turbid coastal waters.
LEAF LITTERFALL AND DECOMPOSITION IN A FOREST OF THE CHACO ARGENTINO

Within an equilibrated forestry ecosystem there is a close relationship between annual leaf litterfall to the soil and litter decay constant. The goal of this work was to determine the leaf litterfall of the black Carob tree [Prosopis nigra (Griseb) Hieron. ] and Quebracho Colorado Chaqueño (Schinopsis balansae Engl.) and the decay constants for leaf litter in the Parque Chaqueño Húmedo Argentino. The annual decay constant (k) was calculated using a single exponential model. The Quebracho Colorado Chaqueño produced greater amounts of vegetative litter material (379.7 kg ha−1) than the black Carob tree 300.6 kg ha−1. The black Carob tree had a higher annual decay constant compared with Quebracho Assuming that a higher decay constant means shorter nutrient retention for time fallen leaves, biogeochemical cycles can be established more rapidly for Prosopis nigra (Griseb) Hieron. than for Schinopsis balansae Engl.
Study of phase transformations in CMSX-6 and CMSX-8 superalloys

Nickel-based superalloys are extensively used mainly in the aircraft and aeronautic industry, particularly in the hottest parts of engines or turbo-reactors. The phase reactions occurring in these heat-resistant materials play a crucial role in many aspects of the processing and service of the highly alloyed materials. Cast Ni-based superalloys are obtained in a complex way and their structure is complicated. Differential scanning calorimetry (DSC) technique was applied for determination of temperature ranges of the phase transformations occurring in the CMSX-6 and CMSX-8 superalloys during heating/cooling processes. Thermophysical properties, including temperatures of the phase transformation, are the critical input parameters in mathematical models of solidification and casting of metallic materials. The literature data concerning phase transformations and performance of the heat treatment for CMSX-6 and CMSX-8 are incomplete and ambiguous. DSC results accompanied by scanning electron microscopy characterization of microstructure of CMSX-6 and CMSX-8 superalloy was applied. The present study will improve the understanding of the fundamental mechanisms of phase transformations of single-crystal nickel-based superalloys.
Statistical Analysis of Linear and Non-Linear Regression for the Estimation of Adsorption Isotherm Parameters

A very common practice during the parameter estimation of adsorption isotherms, including the well-known Langmuir and Freundlich isotherms, consists in manipulating the isotherm equation to obtain a linear equation and estimate the model parameters using a linear least squares method. This procedure is also usually used for estimating the thermodynamic adsorption parameters, despite the fact that personal computers and software are available for prompt implementation of non-linear solutions of the original parameter-estimation problem. For this reason, the main purpose of this work is to show that the use of linear least-squares methods for estimating adsorption isotherm parameters leads to some serious drawbacks, which can be readily avoided through proper use of non-linear procedures and posterior statistical analyses of the parameter-estimation results, enhancing the quality of the obtained results.
Crumb Rubber–Modified Asphalt: Microwave Treatment Effects

Abstract Crumb rubber pretreatment by microwave irradiation before blending with an asphalt matrix improves the properties of rubber–asphalt blends. This treatment cleft the surface vulcanization network, resulting in higher surface activity of the crumb rubber and improved compatibility with asphalt. This new rubber blend exhibited minor temperature susceptibility behaviors and high ductility at 5°C and an improved viscoelastic nature and storage stability. Characterization has also been performed to elucidate the mechanism for this improvement using a microwave treatment technique.
How Do Chinese Grassroots NGOs Fight Local Pollution? An Organizational Perspective

In recent years, the Chinese government started to encourage more stakeholders to participate in the environmental protection field. However, little information told us what role grassroots nongovernmental organizations (GNGOs) can play in the environmental protection field. In this study, the development history of two GNGOs were traced in parallel. The two GNGOs were both established by environmental journalists who wished to mitigate local pollution. However, the development history of the two GNGOs were totally different. I found that two external factors could explain this difference: government’s different willingness on pollution mitigation and the severity of the pollution. In order to mitigate the local pollution, both of the two GNGOs reached out to different stakeholders, especially government agencies, for cooperation. For the government, this cooperation is beneficial to fulfill their environmental protection responsibility. For the two GNGOs, the cooperation is a stable source of legitimacy, which is critical for GNGO’s survival when they worked on pollution mitigation, a relatively controversial field in China. The cooperation, however, strongly depends on founder’s personal relationship with different stakeholders. This dependency brought both of the two EGNGOs into the trap of elite governance.
Isomerization and solution structures of desferrioxamine B complexes of aluminum(3+) and gallium(3+)

The Ga(III) and Al(III) complexes of desferrioxamine B(H 4 DFO + ) have been prepared and purified by cation-exchange liquid chromatography. Both complexes elute as single bands, with elution rates comparable to those measured for the trans isomer(s) of the kinetically inert Cr(HDFO) + complex. The solution thermodynamics of Ga(HDFO) + show that the cationic complex is the only significant species from pH 2 to pH 9. Above pH 9 the complex undergoes hydrolysis. The NMR spectra of both the Ga and Al complexes indicate the presence of two isomers. The kinetics of isomerization of Ga(HDFO) + were studied by variable-temperature 13 C measurements in D 2 O, methanol-d 4 , and dimethyl-d 6 sulfoxide
Effect of the Hydrocarbon Phase on Interfacial and Thermodynamic Properties of Two Anionic Glycolipid Biosurfactants in Hydrocarbon/Water Systems

The surface active properties of highly purified glycolipid (rhamnolipid biosurfactants) of known structure have been studied in detail and their properties are reported. Interfacial tensions (IFT) against different classes of hydrocarbons have been measured experimentally by interfacial tensiometer measurement. The critical micelle concentration (cmc), maximum interfacial excess concentration (Γmax), and the minimum area per headgroup (Amin) can be calculated from the IFT data. Furthermore, the free energy upon adsorption on the interface (ΔGad) and the free energy of surfactant to form micelle (ΔGmic) can be derived from Γmax, Amin, and the cmc. The effectiveness and the distinct properties of micelles formed in the presence of linear, branched, and nomoaromatic solutes was evidenced by lower interfacial tensions against the linear alkanes (Γmin) and a smaller area per headgroup (Amin). Traditional explanations for this micellization behavior focus on more effective intercalation oflinear alkanes into t.
The correlation between metal oxidation state and bond valence parameters for M—O bonds (M = V, Fe and Cu). A simple method to search for the metal oxidation-state independent parameter pairs

Abstract Based on the latest available crystal data and the reported bond valence parameters, the linear correlation between the bond valence parameter R0 with B = 0.37 Å for M—O bonds (M = V, Fe and Cu) and the metal oxidation state n is shown for the first time. For V—O bonds, a linear equation of R0 ∼ n is perfectly established as R0 = 0.0250n + 1.674 (n = 2–5). Similarly, a linear equation for Fe—O bonds is fitted as R0 = 0.0335n + 1.648 (n = 2–4), as well as R0 = 0.0855n + 1.482 (n = 1–3) for Cu—O bonds fitted properly. In addition, the linear correlation between R0 and n within certain range of B values for V—O and Fe—O bonds is also established. Consequently, the oxidation-state independent parameters (R0, B) of (1.788, 0.32 Å) for V—O bonds and (1.795, 0.30 Å) for Fe—O bonds can be derived from the zero slope of the R0 ∼ n straight lines. However, a similar parameter pair for Cu—O bonds cannot be found using this unique approach.