Miracle-dz/UniFAR-FTUs huggingface dataset:
Combining Active Learning with Service Learning: A Student-Driven Demonstration Project

Chemical demonstrations are used as an active-learning tool in a general chemistry course and as a method of outreach to a local middle school. The demonstrations are planned and prepared by groups of students, who first present them to their classmates and then take them to a middle school to present them to groups of middle school children in an event known as Chemistry Day.
Kinetics of Hydrodistillation and Chemical Composition of Essential Oil from Cherry Laurel (Prunus laurocerasus L. var. serbica Pančić) Leaves

Abstract The essential oil was isolated from cherry laurel (Prunus laurocerasus L. var. serbica Pančić) leaves by hydro-distillation in a Clevenger-type apparatus. The kinetics of hydrodistillation was described by a simplified diffusional model. The oil analysis was performed by GC and GC/MS and the main compound identified was benzaldehyde (99.7%), while two other components being identified as (E)-2-hexenal and (Z)-ocimenone were present in insignificant quantities.
SOIL DEGRADATION RELATED TO OVERGRAZING IN THE SEMI-ARID SOUTHERN CALDENAL AREA OF ARGENTINA

The aim of the present study is to determine quantitatively the magnitude of the structural changes that occur in the soil during the degradation process affecting natural grassland in the semi-arid ecosystem of the southern area of the District of the Caldén, Argentina. Topsoil horizons show a reduction in depth from 20 cm in ungrazed sites to 16 cm in grazed sites, mainly as a consequence of soil compression caused by animal hooves. Bulk density values in the first 5 cm of the profile in grazed sites are approximately 27% higher than those in ungrazed sites. Total porosity values in the top few centimeters are, on average, 17% lower in grazed sites, primarily due to the collapse of macropores (>50 μm) and larger mesopores (50-9 μm). Water retention curves for the three depths in the different patches reflect the changes in pore space distribution. Grazing causes a sharp increase in mechanical impedance-an average increment of 210% over ungrazed values in the first 10 cm of soil. There are marked differences in the degree of aggregation in grazed sites compared with ungrazed sites. The former show a lower quantity and density of roots in the top few centimeters of the profile. Changes are also evident in average root diameter as a result of vegetation substitution brought on by overgrazing. The lack of significant differences in soil physical properties in areas subject to different grazing intensities underscores the gravity of the problem caused by animal traffic, which poses a serious threat to the conservation and recovery of the grazed patches.
Physicochemical Properties of Quaternary Ammonium Surfactants with Hydroxyethyl Groups

Abstract Two cationic quaternary ammonium surfactants with hydroxyethyl groups, dodecyl-(2-hydroxyethyl)-dimethylammonium chloride (DHDAC), and dodecyl-di(2-hydroxyethyl)-methylammonium chloride (DHHAC) were synthesized. Their physicochemical properties were investigated systematically by surface tension and conductivity measurements. Various physicochemical parameters were calculated to evaluate the surface activities of these surfactants. The results show that the surface activity increases with increasing the number of hydroxyethyl groups on hydrophilic groups of surfactants. The degrees of counterion binding to micelles of these surfactants were also discussed. The thermodynamic parameters obtained from electric conductivity measurements show that the micelle formation of DHHAC is entropy-driven in the temperature range investigated. However, it is enthalpy-driven for DHDAC.
Soil Organic Carbon Dynamics in Black Soils of China Under Different Agricultural Management Systems

Cultivation can reduce soil organic carbon (SOC) content and lead to soil deterioration, but some agricultural management systems may increase SOC content and soil productivity. This research examined the SOC dynamics during a 50-year cultivation and how long-term agricultural management practices influenced SOC content in a typical black soil (Mollisol) region of P.R. China. The experiments selected four areas with different cultivation periods: uncultivated, five years, fourteen years, and fifty years. In addition, four long-term agricultural managements were initiated in 1992: conventional wheat–soybean rotation, wheat–sweet clover rotation, wheat–soybean rotation with addition of pig manure, and wheat–soybean rotation with addition of wheat straw. The SOC content declined rapidly at early years of cultivation and gradually afterwards. Wheat–soybean rotation with addition of wheat straw or pig manure resulted in a substantial increase in SOC content in 9 years. Thus, proper soil management can improve soil quality and health by increasing SOM content, and mitigate the greenhouse effect by sequestrating carbon dioxide from the atmosphere as indicated by the significant increase of organic carbon content in soil.
First Evaluation of Human Sperm Quality in Various Geographic Regions of Switzerland

A decline in human sperm quality and quantity has been reported in numerous Western countries. This observation was also accompanied by an increase in urogenital malformations. The need for epidemiological studies dealing with unbiased populations in order to understand the causes of these observations is obvious. In Switzerland, the large majority of young men are asked to attend a military camp to be drafted into the army. A few weeks before this camp, conscripts were contacted and invited to participate in a large national study on semen quality. The participation was totally voluntary and anonymous. From September 2005 to June 2007, 770 volunteers filled out a questionnaire, underwent a clinical examination and provided sperm, blood and urine samples. Using self-rated health assessments, the observed cohort could be considered as healthy and no testicular cancer was found. Moreover, the testicular volumes, measured using Prader's orchidometry and ultrasonography, were comparable to those already published for young male populations. The median sperm concentration was 47 x 10(6)/ml, which is close to the concentration reported in Denmark, known to have the highest incidence of testicular cancer in Europe. Statistically significant differences were observed between regions with a lower sperm concentration for men residing in the Alps (43 x 10(6)/ml) and in the Zurich area (36 x 10(6)/ml) compared to men from West Plateau (54 x 10(6)/ml) and from the Jura (54 x 10(6)/ml). Such a regional discrepancy could be related to environmental factors, including endocrine disruptors. In order to confirm such regional differences more volunteers from the already studied regions should be studied and other parts of the country should be investigated. The rather low sperm concentration of Swiss young volunteers should be considered as a national health issue and investigated further.
Plant and Soil Responses to the Application of Composted MSW in a Degraded, Semiarid Shrubland in Central Spain

Composted municipal solid waste (MSW) was assessed as a soil amendment material for restoring the canopy cover of a degraded soil in an area with a Mediterranean climate. Four rates (0, 40, 80 or 120 Mg ha−1) of MSW were surface-applied to a calcareous soil in central Spain and the effects on soil properties and the native plant community recorded over the next five years. Soil N, P and K levels increased significantly after application. Soil organic carbon (OC) increased with the amount of MSW applied, but the differences were small and inconsistent. Soil total Zn, Pb, Ni and Cu increased in the MSW-treated soils compared to the controls, but levels were still below the maximum allowed by Spanish legislation. DTPA-extractable soil Zn and Cu were the only heavy metals studied that increased with MSW application, but their concentrations were still adequate for plant growth. Total aerial plant biomass yields and canopy cover increased with MSW amendment compared to the control treatment. Plant production increased three fold in the amended plots in the first years and than declined with time, although no consistent trends were observed. The percentage canopy cover ranged from approximately 82 to 100 % in the MSW treatments and from 43 to 49% in the control throughout the study period. Native plant species richness decreased slightly with increasing MSW rates. Differences in the plant communities developing on the control and MSW-treated plots were observed, with a reduction in perennial species and an increase in annual species after five years. Plant tissue N, P, K, Zn and Cu levels generally increased with the MSW rate. Thus, MSW application have a positive effect on the soil chemical characteristics and on the native vegetation without causing environmental damage. MSW may therefore be of use in the rehabilitation of ecosystems similar to that studied.
Utilization of snail shells to synthesise hydroxyapatite nanorods for orthopedic applications

Snail shells are plentiful in nature and consist of mainly CaCO3. Here they have been effectively utilized to synthesize hydroxyapatite (HA) nanorods by a facile and rapid microwave irradiation method with the help of ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The conversion of snail shells into HA occurs via the formation of a Ca–EDTA complex which subsequently reacted with phosphate at pH ≈ 10 under microwave irradiation. The obtained product consists of B-type carbonated HA nanorods and can be a potential candidate for biomedical applications.
Determination of the Optimum NiS Fire Assay Parameters for Pt, Pd, and Rh in Automotive Exhaust Catalytic Converters

This work investigates the performance of the nickel sulfide fire assay (NiS-FA) for the pyrometallurgical analysis of platinum group elements (PGEs) from mixtures of automotive exhaust catalytic converters (e.g., gasoline, diesel, and diesel particular filter) by assessing the effects of various flux materials and reaction parameters on platinum, palladium, and rhodium recovery. Inductively coupled plasma mass spectrometry and atomic absorption spectroscopy (AAS) are used for the analysis of the NiS-FA beads. We found that the optimum recovery (at least 99.0%) was achieved with reaction of 11.5 g of flux (0.53 w/w ratio, sodium tetraborate:sodium carbonate), 1 g nickel, and 0.84 g sulfur (1.2 w/w ratio, Ni:S) per gram of sample for 90 min at 975°C. Reference standards (NIST SRM 2557) were used to compare efficiencies and identify the optimum conditions. The results are consistent with certified values and PGEs could be recovered within the 95% confidence level. The precision (<4.0% RSD) of all measurements, expressed as percentage relative standard deviation (SD), ranged up to 3.0%.
Validation of Advanced Computational Methods for Determining Flame Transfer Functions in Gas Turbine Combustion Systems

The operation envelope of modern gas turbines is affected by thermoacoustically induced combustion oscillations. The understanding and development of active and passive means for their suppression is crucial for the design process and field introduction of new gas turbine combustion systems. Whereas the propagation of acoustic sound waves in gas turbine combustion systems has been well understood, the flame induced acoustic source terms are still a major topic of investigation. The dynamics of combustion processes can be analyzed by means of flame transfer functions which relate heat release fluctuations to velocity fluctuations caused by a flame. The purpose of this paper is to introduce and to validate a novel computational approach to reconstruct flame transfer functions based on unsteady excited RANS simulations and system identification. Resulting time series of velocity and heat release are then used to reconstruct the flame transfer function by application of a system identification method based on Wiener-Hopf formulation. CFD/SI approach has been applied to a typical gas turbine burner. 3D unsteady simulations have been performed and the flame transfer results have been validated by comparison to experimental data. In addition the method has been benchmarked to results obtained from sinusoidal excitations. © 2007 ASME
Surface speciation models of calcite and dolomite/aqueous solution interfaces and their spectroscopic evaluation

The composition and density of surface hydroxyl and carbonate groups on calcite and dolomite after contact at 25 °C with solutions of different pH (3 to 12) and carbonate concentration (10-4 ≤ ∑CO2 ≤ 0.1 M) were monitored by means of diffuse reflectance infrared (DRIFT) spectroscopy. Both for calcite and dolomite, broad high-intensity absorbance bands at about 3400 and 1600 cm-1 were observed at pH below 6 and carbonate concentration below 10-3 M. These bands are assigned to hydroxyl groups present at the mineral surfaces. At higher pH and ∑CO2, the intensity of these bands significantly decreases. On the contrary the intensity of the broad double band at about 1400 cm-1 due to carbonate species (surface and bulk) for both minerals was found to increase significantly with increasing solution pH and carbonate concentration, being the lowest at pH ≤ 5 and ∑CO2 ≤ 10-3 M. These observations correlate well with the surface speciation for calcite or dolomite/aqueous solution interface predicted based on surface.
Charge emissions from electrosprays in vacuum: Mixtures of formamide with methylammonium formate

The charge/mass distribution f(q/m) of nanodrops and ions electrosprayed in vacuum from mixtures of formamide (FM) and methylammonium formate (MAF) is studied by time of flight mass spectrometry at MAF/FM volumetric concentrations of 5%, 10%, 25%, and 50%. Positive and negative polarities yield comparable f(q/m) curves, though the negative mode yields ∼30% larger currents. On shifting from the highest to the lowest liquid flow rates at which a cone-jet is stable, the more conductive solutions evolve from mostly drop to primarily ion emission. A purely ionic regime is not reached under any condition, but the drops achieve unusually high q/m. As a result, these sprays have excellent electrical propulsion characteristics, some being able to cover a 25-fold range of average q/m with a polydispersive efficiency typically in the range of 80%. Results of formamide electrolytes with formates and nitrates of several other amines are more briefly reported.
Polyynes Production in a Solvent‐Submerged Electric Arc Between Graphite Electrodes. I. Synthesis and Spectroscopy

Abstract The electric arc between graphite electrodes submerged in solvents like decahydronaphthalene (DHNP), acetonitrile, n‐hexane, and toluene produces a mixture of polyynes having the general formula H(C≡C) m H with m an integer: 1, 2, 3, …, m. Polyynes having m = 8, thus having at least 16 carbon atoms have been identified together with their lower homologues by electronic absorption spectroscopy. The yield of polyynes depends from the temperature of the arc: the highest the temperature the larger the production of long chain polyynes. The elemental carbon necessary for the production of the polyynes is supplied by the carbon vaporization of the graphite electrodes and is almost independent from the chemical nature of the solvent.
Intrinsic kinetics of hydrogenation of benzene on nickel catalysts supported on kieselguhr

Intrinsic rates of gas-phase benzene hydrogenation to cyclohexane were measured at 67.6/sup 0/-90.5/sup 0/C, 1000-3000 mm Hg hydrogen pressure, and 70-286 mm Hg benzene pressure with a commercial catalyst containing 67Vertical Bar3< nickel on kieselguhr (ICI 42-1). The data and available results obtained with catalysts of different nickel contents were successfully correlated by a rate expression which implies that gaseous hydrogen reacts with chemisorbed benzene.
Mathematical Analysis for Growth Depression of Vibrio parahaemolyticus in Shrimp under a High Carbon Dioxide Atmosphere

Growth depression of Vibrio parahaemolyticus in pink shrimp under a high CO2 atmosphere was studied. A strain was isolated from prawn and identified as V. parahaemolyticus. The identified strain was used to inoculate pink shrimp and stored at 20°C under air, N2, and CO2. The plate count under CO2 16 h after inoculation was significantly lower than those under air and N2. The plate count under a steady state of CO2 was lower by log 3.6 to log 3.7 than those under air and N2. The growth of V. parahaemolyticus in/on the shrimp was fitted and simulated using the Gompertz equation and a new logistic model, to determine its growth rate parameters. CO2 reduced the value of the parameter equivalent to maximum plate count.
Effects of EDTA and EDDS on Heavy Metal Activation and Accumulation of Metals by Soybean in Alkaline Soil

The application of chelating agents for phytoextraction has demonstrated that it is an efficient method to activate heavy metals in polluted soil. We conducted pot experiments using soybean, which has been considered an indicator plant, to study the effects of EDTA and EDDS on heavy metals’ activation, and on the soybean. The study results indicated that EDDS decreased the chlorophyll content of the leaves and increased the malondialdehyde (MDA) content of the soybean. EDTA also decreased the chlorophyll content of the leaves. EDDS had a strong influence on activating Cu (2583-8900-fold) and Zn. The addition of 5 mmol kg−1 of EDDS markedly increased the uptake of metals. Compared with the control, EDDS increased the Cu uptake (100-205-fold). EDTA greatly increased the activation of heavy metals; it also increased Cu uptake in a concentration-dependent manner. EDTA also increased the biological concentration factor (BCF) and the transfer factor (TF) in a concentration-dependent manner. The BCF and the TF reached maximum levels when 5 mmol kg−1 EDDS was applied to the pots.
Growth‐irradiance relationships in phytoplankton1

The steady state growth rates of three species of marine phytoplankton, Thalassiosira weisflogii, Isochrysis galbana, and Prorocentrum micans, were followed in turbidostat culture. At each growth irradiance, photosynthesis and respiration were measured by following changes in oxygen. Together with measurements of optical absorption cross sections, cellular chlorophyll, carbon and nitrogen, and excretion rates as well as knowledge of the quantum flux, the quantum requirement for growth and photosynthesis were calculated. Our results suggest that variations in growth rate caused by changes in irradiance may be related to changes in respiration rates relative to growth as well as changes in optical absorption cross sections for a given species. Interspecific differences in growth rate at a given irradiance are not related to changes in respiration however, but are primarily attributable to differences in optical absorption cross sections normalized to chlorophyll and differences in chlorophyll:carbon ratios.
Biosolids recycling : Nitrogen management and soil ecology

Biosolids are municipal wastewater treatment solids that meet regulatory standards for land application. Most biosolids are a rich source of N, P, and micronutrients. Although the use of biosolids on food crops remains controversial in the public eye, decades of research have led to the development of regulations for the safe and beneficial use of biosolids in agriculture. Emerging areas of research include biosolids in commercial and home horticulture, the fate of pathogens and organics in biosolids, the use of biosolids in the remediation of contaminated sites, and biosolids effects on soil ecology. Nutrient management remains the most critical day-to-day issue for land application of biosolids. Recent research on plant-available nitrogen (PAN) in biosolids has found that N availability is similar over a range of biosolids processing types, and that growing-season climate is a key factor affecting available N. Regionally based predictions of PAN have been developed for the United States, and could be ex.
Resonant X-ray scattering studies of epitaxial complex oxide thin films

Resonant anomalous X-ray reflectivity (RAXR) is a powerful technique for measuring element-specific distribution profiles across surfaces and buried interfaces. Here, the RAXR technique is applied to characterize a complex oxide heterostructure, La0.6Sr0. 4Co0.2Fe0. 8O3−δ, on NdGaO3, and the effects of data sampling and model-dependent fitting procedures on the extracted elemental distribution profile are evaluated. The strontium profile through a 3.5 nm-thick film at 973 K and at an oxygen partial pressure of 150 Torr (1 Torr = 133.32 Pa) was determined from the measured RAXR spectra. The results demonstrate that in situ RAXR measurements can provide key insights into temperature- and environment-dependent elemental segregation processes, relevant, for example, in assessing the cathode performance of solid oxide fuel cells.
Boron tolerance of pea (Pisum sativum)

Abstract Pea plants were grown to full maturity in nutrient solutions with added B levels ranging from 0 to 18 mg/1. Toxicity symptoms were observed and described. Parameter yields were significantly decreased by B concentrations of or above 2 mg/1. Leaf B contents increased for each added B level. Boron contents of stems, roots, grain, and pods increased significantly at the three highest B levels. Leaf B contents of 50 to 300 ppm were within sufficient range at flowering time. Concentration higher than 500 ppm were in the severe B toxicity range. Calcium contents in leaves and roots decreased as B level increased both in the nutrient solution and in the leaves. Ca/B ratios in the leaves at flowering of 75 to 400 were associated to maximum yields Pea is classified as a B sensitive crop.
Soil amendments and water-stable aggregation of a desurfaced Dark Brown Chernozem

Aggregate stability, which influences soil resistance to wind and water erosion, can be improved by the application of organic amendments. In spring 1992, a desurfaced Dark Brown Chernozem in southern Alberta was amended with six animal manures, four crop residues and two rates of phosphate fertilizer, to determine their efficacy in restoring soil productivity. Eroded check (no amendment) and topsoil check (no desurfacing) treatments were left for comparison. One year later, wet aggregate stability at five levels of aggregate pre-wetting was determined. Aggregate stabilities of crop residue-amended soils were significantly higher (P < 0.01) than those of soils treated with animal manures or fertilizer/checks at all wetness levels. Significant (P < 0.01) quadratic response and plateau relationships between aggregate stability and soil water content showed that there was a threshold moisture content for maximum stability. With the onset of rainfall, aggregates on the crop residue-amended treatments would re.
meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane dihydroperchlorate monohydrate

The crystal structure of the title compound meso-5,5,7,12,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-4,11-diium diperchlorate monohydrate, C 16 H 38 N 4 2+ . 2ClO 4 - . H 2 O, has been determined. The cationic ring contains two protonated and two secondary amine N atoms. The protonated N atoms display one long and one short N-C bond, with values of 1.526 (4) and 1.484(4)A, respectively. Similarly, the secondary amine N atoms also display one long and one short N-C bond, with values of 1.485 (4) and 1.455 (4) A, respectively. A rather complicated hydrogen-bonding space system is present in the crystal.