Miracle-dz/UniFAR-FTUs huggingface dataset:
Kinetic model for separation of particle mixtures by interfacial partitioning

A mechanistic study is presented on the partition behavior of mixtures of particles in interfacial partitioning with liquid two-phase systems. A model is developed based on a mechanism of competitive adsorption of particles at the liquid-liquid interface. In this model, it is assumed that partitioning is the result of a dynamic process of continuous adsorption and desorption of particles at droplet interfaces. It is shown that under certain conditions such a process can be described by means of Langmuir-type adsorption isotherms. The model is tested with partition data of mixtures of ampicillin and phenylglycine crystals in a water/n-pentane system, which leads to a reasonable quantitative description. The results indicate that for this particular system, adsorption of crystals at the interface occurs up to amounts that are needed for a monolayer coverage. In case larger amounts of crystals are present, partitioning of particles is subject to a competition for the available interfacial area. In such a case, the kinetics of adsorption and desorption of the particles to the interface seem to differ from a situation where the interface is partly uncovered. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1156–1168, 2004
Evaluation of Surface Acido‐Basic Properties of Inorganic‐Based Solids by Model Catalytic Alcohol Reaction Networks

Abstract The characterization of acido‐basic properties of the surface of inorganic solids is essential to understand the behavior of catalysts during heterogeneous catalyzed reactions. The use of alcohols as reactive probe molecules to investigate these properties has been developed since the 1970s, and in 1991, a new alcohol, 2‐methylbut‐3‐yn‐2‐ol (MBOH), was proposed. This review sums up the knowledge accumulated for 15 years on this model reaction network and compares its advantages with those of other alcohols. The operating conditions are reviewed, and deactivation phenomena are analyzed. Then, from investigations of correlations with other techniques able to reveal the acido‐basic properties of surfaces, it is concluded that MBOH appears to be the most valuable reactive probe molecule as the nature of the sites involved in the different routes of its network is unambiguous. The links that may exist between the rate of a model reaction and the thermodynamic acido‐basic properties of the surface are then discussed. It is shown that even when true kinetics parameters are available, they are not necessarily correlated to thermodynamic parameters. What can be expected from a model reaction network is to evaluate the reactivity of a surface along an acidic or a basic route. In basic sites, this reactivity may be related to the nucleophilicity of the surface or to the way the deprotonated intermediate is stabilized on the surface. It can be used to follow the modifications of a series of materials during synthesis and to identify the factors governing a reaction of practical interest.
Thermophysical Properties of

The results from fast-pulse heating experiments (of duration 60 μs) performed on pure palladium are presented. Thermophysical properties derived include specific enthalpy, enthalpy of fusion, electrical resistivity, isobaric heat capacity, thermal conductivity and thermal diffusivity, over a range of temperatures from the melting transition up to some hundred degrees higher in the liquid state. Additionally, normal spectral emissivity at wavelength 684.5 nm is presented,
Mode of Transport of Surface‐Applied Phosphorus‐33 through a Clay and Sandy Soil

Phosphorus (P) is the limiting nutrient for primary production in most freshwater ecosystems. The magnitude of P leaching from agricultural soils is therefore critical. Preferential flow has been proposed as a major cause for high P losses in structured clay soils. Undisturbed soil of two texturally different soils, that is, a clay soil in which preferential flow was expected to be the main mode of water transport and a sandy soil where piston flow is the dominant process, were used in this study. Use of labeled P made it possible to determine the origin of leached P. An equivalent of 100 kg P ha -1 , labeled with 33 P, was added to the soil surface of each lysimeter. Water equivalents to 100 mm were added on five occasions with 7 d between each watering event. Ponded flow conditions were established during periods when water was added, to trigger preferential flow behavior. Phosphorus leaching loads from clay columns were much higher than P loads from sand columns. The average P leaching load for the five clay columns was 4.0 kg ha -1 , compared to only 56 g ha -1 for the three sand columns. The main part of leached P was in dissolved (PO 4 -P) form. The recently added P prevailed in leachate from the clay soil indicating rapid transport of added P from the soil surface through the profile via macropores.
Effect of Oxalate Anions on Zinc Electrodeposition from an Acidic Sulphate Bath

Zinc coatings were electrodeposited on steel substrate. The effect of oxalate anions as chelating agents on nucleation and growth mechanism, surface morphology, predominant texture and corrosion behaviour of zinc electrodeposits was investigated. Evaluation of nucleation mode of zinc in the presence and absence of oxalate anions showed that the instantaneous nucleation is predominant in both cases. From the AFM images, the nuclei densities for zinc deposition were 3.5 x 10 9 and 2 x 10 9 cm ―2 in the absence and presence of oxalate anions, respectively. These are one order of magnitude higher than those obtained by analysis. Electrochemical impedance spectroscopy revealed that in the bath containing oxalate anions, the growth of deposit is semi-infinite diffusion controlled. While in the absence of oxalate anions, the charge transfer control was governed. In the absence of oxalate anions, the texture components of zinc coating were mostly basal and low angle pyramidal planes, whereas in the presence of oxalate anions, the high angle pyramidal and prism planes were dominant. Furthermore, oxalate anions changed the zinc surface morphology from packets of hexagonal platelets to a granular nature. In the presence of oxalate anions, the zinc coating produced had a better corrosion resistance than that deposited from bath without oxalate anions.
Global and local view on the electrochemically induced degradation of polyelectrolyte multilayers: from dissolution to delamination

The electrochemically tailored degradation of polyelectrolyte assemblies holds great promises for the design of inexpensive, easily prepared and precise controlled release systems. However, the conception of such electrochemically responsive platforms for drug or gene delivery requires a detailed understanding of the degradation process of the polyelectrolyte multilayer in which the active species to release are incorporated. To this end, we assess here the influence of an applied electric potential on different polyelectrolyte systems, combining global and local investigation techniques. In situ atomic force microscopy allows us to evidence morphological changes at the nano- and micro-scale, while the investigation at a larger scale by optical waveguide lightmode spectroscopy brings complementary information relating not only to material release into the bulk solution, but also to ion migration and swelling. Weak and highly hydrated poly(L-lysine)/hyaluronic acid assemblies with thicknesses up to several hundreds of nanometre continuously dissolve upon electrochemical trigger. However, stronger and more compact films made of poly(allylamine hydrochloride) and poly(styrene sulfonate) dissolve only if their thickness is of a few tens of nanometres, while thicker films delaminate from the electrode. Additional results obtained with composite films combining both polyelectrolyte systems allow us to present mechanisms based on the continuous formation of protons at the electrode surface due to water electrolysis which fully describe the dissolution and the delamination processes. In addition, the study also reveals a novel approach for the release of free-standing polyelectrolyte membranes, which is of great interest for the development of mechanical sensors, separation membranes, or micromechanical devices.
Seasonal dynamics in wheel load‐carrying capacity of a loam soil in the Swiss Plateau

Subsoil compaction is a major problem in modern agriculture caused by the intensification of agricultural production and the increase in weight of agricultural machinery. Compaction in the subsoil is highly persistent and leads to deterioration of soil functions. Wheel load‐carrying capacity (WLCC) is defined as the maximum wheel load for a specific tyre and inflation pressure that does not result in soil stress in excess of soil strength. The soil strength and hence WLCC is strongly influenced by soil matric potential (h). The aim of this study was to estimate the seasonal dynamics in WLCC based on in situ measurements of h, measurements of precompression stress at various h and simulations of soil stress. In this work, we concentrated on prevention of subsoil compaction. Calculations were made for different tyres (standard and low‐pressure top tyres) and for soil under different tillage and cropping systems (mouldboard ploughing, direct drilling, permanent grassland), and the computed WLCC was compared with real wheel loads to obtain the number of trafficable days (NTD) for various agricultural machines. Wheel load‐carrying capacity was higher for the top than the standard tyres, demonstrating the potential of tyre equipment in reducing compaction risks. The NTD varied between years and generally decreased with increasing wheel load of the machinery. The WLCC simulations presented here provide a useful and easily interpreted tool to guide the avoidance of soil compaction.
Temperature Dependent Rubidium-Helium Line Shapes and Fine Structure Mixing Rates

Abstract : Diode Pumped Alkali Lasers (DPALs) are a new type of laser that uses alkali metal vapor as a gain medium and a bu er gas to control the line shape and kinetics. While these systems were first demonstrated in 2003 [48] they have just recently been scaled to the kilowatt power levels in 2012 [18]. To achieve these powers, the design of the gain cell relied on a set of incomplete line shape and kinetic data. The current focus areas of DPAL research are the continued power scaling of the systems and basic science research into the rates involved within the system. The purpose of this research is to determine the physical parameters of various alkalinoble gas interactions with a high degree of accuracy. The physical parameters of interest here include pressure broadening (), pressure shift ( ), asymmetry ( 0), the quenching rates (k20, k10), and spin-orbit (SO) mixing rates (k12, k21). Various measurements of these line shape parameters and the rates associated with these systems have been taken over the years at low temperatures and usually low pressures. Temperatures of the measurements range from 320 K [39] to 394 K [68] with pressures of 300 Torr [68]. Various theories including the semi-classical approach of Anderson Talman [4, 43] and the full quantum mechanical treatment of Baranger [7] can be used to predict line shape parameters provided that the interaction potentials, are well known.
Determination of speciation and bioavailability of Cd in soil solution using a modified soil column Donnan membrane technique

Abstract The concentration of free metal ion (Mz+) has a strong impact on bioavailability and toxicity. In this study, Cd2+ concentration in soil solution was measured by a modified soil column-Donnan membrane technique (S-DMT). Compared with the previously reported DMT, the equilibrium time was relatively short (8 hours) and the multiple metals in the solution can be determined using ICP-AES. This technique was successfully applied in a pot experiment to evaluate Cd speciation and availability to rice. The measured Cd2+ concentration in the soil solutions agreed with the model calculation and correlated very well with the rice growth and the Cd uptake in rice.
Quantitative analysis of corn zeins by capillary electrophoresis.

ABSTRACT Kjeldahl analysis is commonly used to measure zein proteins in corn maize (N × 5.7) with no attempt to eliminate contribution from other nitrogen sources. In this study, dry milled corn was extracted with 70% ethanol or 0.1N NaOH and the zein content of the extract measured using capillary electrophoresis in the presence of sodium dodecyl sulfate. The amount of zein protein in alcohol extracts, using this method, was in good agreement with that determined by Kjeldahl nitrogen analysis. However, less than half of the Kjeldahl nitrogen in the alkaline extracts could be attributed to corn zein. Reproducibility expressed as relative standard deviation for migration time and peak area was 0.10 and 1.05, respectively. The technique permits rapid analysis of a large number of samples without interference from other compounds present in the extracts.
Gold Nanoclusters‐Based Nanoprobes for Simultaneous Fluorescence Imaging and Targeted Photodynamic Therapy with Superior Penetration and Retention Behavior in Tumors

Gold nanoclusters (GNCs) attract increasing attention due to their potential applications in sensing, catalysis, optoelectronics, and biomedicine. Herein, the formation of highly fluorescent glutathione (GSH)‐capped GNCs is achieved through the delicate control of the reduction kinetics and thermodynamic selection of the Au(I)–SG complexes. Furthermore, the GNCs‐based nanoprobes are developed by the covalent coupling folic acid (FA) and PEG (polyethylene glycol) on the surface of GNCs directly, followed by trapping photosensitizer (chlorin e6, Ce6) within PEG networks and attaching to the GNCs surface. The fabricated nanoprobes (Ce6@GNCs‐PEG2K‐FA) possess a uniform particle size (hydrodynamic diameter ≈6.1 ± 1.2 nm), without affecting the yield of singlet oxygen of the trapped Ce6. In vitro studies show the enhanced cellular uptake and satisfactory photodynamic therapy (PDT) effectiveness toward MGC‐803 cells when compared with free Ce6. The biodistribution and excretion pathway studies of the nanoprobes in MGC‐803 tumor‐bearing nude mice reveal their superior penetration and retention behavior in tumors, while the preserved features of renal clearance and stealthy to reticulo‐endothelial system are mainly attributed to the small hydrodynamic diameters and the FA‐capped PEGylated ligands. The enhanced PDT efficacy and the nontoxicity to mice provide an exciting new nano‐platform with promising clinical translational potential.
Kinetic Modeling of the Hydrolysis of Acetic Anhydride at Higher Temperatures using Adiabatic Batch Reactor (Thermos-Flask)

The kinetics of the reactions of acetic anhydride-excess water has been studied at higher temperatures up to 366K under adiabatic conditions in a thermos-flask fitted with a negative coefficient thermistor and kinetic data reported in this work. The same techniques were applied for the kinetic studies of excess acetic anhydride-water reactions at higher temperature up to 368 K. The reaction kinetics of excess acetic anhydride-water reactions which has not been determined previously was modeled using the same adiabatic analysis and the average activation energy, heat of reaction, pre-exponential factor and the order of reaction with respect to water has been determined. The studies have shown that the two processes appear to be completely different and might proceed through different reaction mechanisms pathways for the production of acetic acid.
Crystal structure of (1S,3S)-2-benzyl- 6-hydroxy-8-methoxy-1,3-dimethyl- 1,2,3,4-tetrahydroisoquinoline hydrobromide

The title compound was prepared by N-benzylation of the corresponding secondary amine and transformation into its hydrobromide. It crystallizes from ethanol orthorhombically in the space group P2 1 2 1 2 1 with a = 1128.4(4), b = 2162.6(7), c = 769.2(2) pm
The relationship between molecular structure and the incidence of the NTB phase

In this work, we present the first part of a study into the relationship between molecular structure and the occurrence of the ‘twist-bend nematic phase’ (NTB). Given the large amount of chemical space that might reasonably be expected to give rise to the NTB phase, this paper is only concerned with methylene-linked bimesogens bearing polar terminal groups based on the initial work of George Gray on cyanobiphenyls. As with other studies, we find that the NTB phase is observed only for materials that contain an odd number of methylene units in the spacer chain. It also appears that, in a given series of materials, there is a weak negative correlation between the dipole moment of the individual mesogenic units and the thermal stability of the NTB phase. Furthermore, we find that increasing the length–breadth ratio of the individual mesogenic units also provides a significant increase in the thermal stability of the NTB phase. The electrooptic behaviour of two materials, one with a terminal nitrile unit and one with an isothiocyanate group, was investigated. The NTB phase of the NCS-terminated material can be switched with a large applied voltage (20 V μm−1); however, the analogous nitrile-terminated material showed no electrooptic response under these conditions. Either the threshold voltage to switching is simply lower for isothiocyanate materials than nitriles or that there is more than one phase currently identified as the twist-bend nematic.
The permanganate oxidation of thymidine

Thymidine was oxidised with potassium permanganate at pH 8.5 at 37° and the products separated by paper chromatography. The following were identified: 5,6-dihydroxy-5,6-dihydrothymidine (‘thymidine glycol’), N-(2-deoxy-D-ribofuranosyl)-N′-pyruvoylurea, N-formylurea, and urea. A component, probably 2-deoxy-D-ribofuranosylurea was detected but it amounted to less than 4% of the reaction products. In addition were present three acidic products probably produced by the oxidation of the primary alcohol group at position 5′. Almost no 2-deoxy-D-ribose was present so it apparently must also have been oxidised to acidic products. 5,6-Dihydroxy-5,6-dihydrothymidine was obtained also by oxidation of thymidine with osmium tetroxide and barium chlorate.
Capstan equation for strings with rigidity

The effect of string rigidity on the capstan equation is considered. Two cases which cover the most likely situations are distinguished - contact of the string with the peg at a point, and contact over an arc. The analysis of these situations is facilitated by an approximation derived for the curvature for the leads of string on either side of the peg. If the friction is governed by Amontons' law the correction of the capstan equation for string rigidity will usually be small, but in the case of arc contact and load-dependent coefficient of friction, the correction could be important.
Study of Nutrient Content Variation in Bulb And Stalk of Onions ( Allium Sepa ) Cultivated in Aliero, Aliero, Kebbi State, Nigeria

The proximate, macro and trace-elements, vitamins A and C, and oxalate compositions were determined in onion bulbs and their stalks from three agricultural fields in Aliero, Kebbi state. The bulbs and stalks contained closely related mean values of 93.11g/100g and 91.70g/100g, 6.48g/100g and 6.74g/100g as moisture and crude protein contents respectively. Values of 4.26g/100g (bulbs) and 13.56g/100g (stalks) were observed as ash content, while their fibre contents were 13.56g/100g (bulbs) and 9.33g/100g (stalks). The macro element concentration in the bulbs was in the order Ca>Mg>K>P>Na while that of the stalks was Mg>Ca>K>P>Na. For the trace elements, the order was Fe>Zn>Mn>Cu>Pb>Ni>Cd for the bulbs and Fe>Mn>Zn>Cu>Ni>Pb>Cd for the stalks. Only Iron concentrations were observed to be higher than (100-500μgg-1) the normal Fe concentrations in plants. There were significant differences (p Keywords: Onion bulbs and stalks, proximate, nutrient elements, vitamins A and C; oxalate
Biodegradation kinetics of trans-4-methyl-1-cyclohexane carboxylic acid in continuously stirred tank and immobilized cell bioreactors

BACKGROUND: Naphthenic acids are carboxylic acid compounds of oil sands wastewaters that contribute to aquatic toxicity. Biodegradation kinetics of an individual naphthenic acid compound in two types of continuous-flow bioreactors were investigated as a means of improving remediation strategies for these compounds. RESULTS: This study evaluates the kinetics of biodegradation of trans-4-methy-1-cyclohexane carboxylic acid (trans-4MCHCA) using two bioreactor systems and a microbial culture developed in previous work. Using a feed concentration of 500 mg L−1 the biodegradation rate of trans-4MCHCA in the immobilized cell bioreactor was almost two orders of magnitude higher than that in a continuously stirred tank bioreactor. The maximum reaction rates of 230 mg (L d)−1 at a residence time of 1.6 d (40 h) and 22 000 mg (L d)−1 at a residence time of 2.6 h were observed in the continuously stirred tank and immobilized cell bioreactors, respectively. In a second immobilized cell system operating with a feed concentration of 250 mg L−1, a comparable maximum reaction rate (21 800 mg (L d)−1) was achieved at a residence time of 1.0 h. CONCLUSION: The use of immobilized cell bioreactors can enhance the biodegradation rate of naphthenic acid compounds by two orders of magnitude. Further, biodegradation greatly reduces the toxicity of the effluent wastewater. Copyright © 2009 Society of Chemical Industry
Using PUF disk passive samplers to simultaneously measure air concentrations of persistent organic pollutants (POPs) across the Tuscany Region, Italy

Abstract Passive air samplers consisting of polyurethane foam (PUF) disks were deployed simultaneously over 2–4 month periods from April to July 2008 at 19 locations throughout the Tuscany Region at urban (n = 9), rural (n = 7) and agricultural sites (n = 3). The purpose of the study was to assess the gas–phase air concentrations of PCBs, OCPs, PBDEs and PAHs on a local and regional scale. Derived air concentrations (pg m −3 ) ranged from below detection limit (BDL) to 300 for Σ 6 PCBs and from BDL to 30 for Σ 3 PBDEs. As expected, the highest PCB concentrations (pg m −3 ) were observed at urban sites, peaking in Piombino (300). PBDEs, however, exhibited a “reverse gradient” (i.e. rural>agricultural>urban) with highest air concentration at the rural site, Arcidoso (30). Levels of OCPs showed less distinct differences among the three site types. The most frequently detected OCPs were Endosulfan I, γ–HCH and α–HCH. Endosulfan I ranged from BDL to 2 200 pg m −3 , α–HCH from BDL to 610, and γ–HCH from BDL to 1 100. The high air concentrations of HCHs were surprising and possibly due to continued and illegal use – especially at agricultural and urban sites that exhibited the highest levels in air. PAHs showed highest concentrations (pg m −3 ) at agricultural and urban sites, ranging from 290 to 4 700 and were generally consistent with other data sets from Europe. PAHs were dominated by the 3–ring PAHs (76 ± 6)%, with phenanthrene alone accounting for (45 ± 11%) of the total PAHs. This study demonstrates the feasibility of using PUF disks as time–integrating passive air samplers for assessing local and regional scale concentrations of a wide range of POPs in central Italy. Given their low cost and simplicity, passive air samplers are the preferred option for conducting concurrent sampling at multiple sites for monitoring and research purposes.