Miracle-dz/UniFAR-FTUs huggingface dataset:
Dynamics of the methanogenic archaeal community in anoxic rice soil upon addition of straw

Addition of rice straw, which is a common practice in rice agriculture, generally results in enhanced production and emission of the greenhouse gas methane (CH4). However, it is unclear whether straw addition affects only the activity or also the composition of the methanogenic microbial community. It is also unclear to what extent methanogenic archaea would be able to proliferate in the soil. Anoxic slurries of Italian rice‐field soil produced CH4 after a lag, during which ferric iron and sulfate were reduced. Addition of rice straw slightly decreased this lag and greatly enhanced the subsequent production of CH4. At the same time, addition of rice straw enhanced the intermediate production of H2 and acetate that served as the methanogenic substrates. Compared with the unamended control, the addition of rice straw resulted in an increased concentration of phospholipid fatty acids in the soil. Quantitative ‘real‐time’ PCR targeting the 16S rRNA gene also showed increased copy numbers of both Bacteria and Archaea in the straw‐amended soil at the end of the experiment. The composition of the archaeal community was followed over time by terminal restriction length polymorphism (T‐RFLP) analysis of the archaeal 16S rRNA genes extracted from straw‐amended soil and the control. Rice Cluster‐I (RC‐I) methanogens and Methanosarcinaceae were the most abundant methanogenic populations, followed by Methanobacteriales, Methanomicrobiales and Methanosaetaceae. Addition of rice straw resulted in a relative increase of Methanosarcinaceae and Methanobacteriales and a relative decrease of RC‐I methanogens and Methanomicrobiales. Our results revealed a dynamic methanogenic community in anoxic rice‐field soil and showed that addition of organic matter selectively enhanced the growth of particular methanogenic populations, which were apparently better adapted to the presence of straw than the others. The extent of archaeal growth was consistent with that expected theoretically from the ambient Gibbs free energies of hydrogenotrophic and acetoclastic methanogenesis.
Optimal control of leachate recirculation for anaerobic processes in landfills

A mathematical model for the degradation of the organic fraction of solid waste in landfills, by means of an anaerobic bacterial population, is proposed. Additional phenomena, like hydrolysis of insoluble substrate and biomass decay, are taken into account. The evolution of the system is monitored by controlling the effects of leachate recirculation on the hydrolytic process. We investigate the optimal strategies to minimize substrate concentration and recirculation operation costs. Analytical and numerical results are presented and discussed for linear and quadratic cost functionals.
Electrostatic fabrication of oleylamine capped nickel oxide nanoparticles anchored multiwall carbon nanotube nanocomposite: A robust electrochemical determination of riboflavin at nanomolar levels

A simple and strong electrostatic adsorption of oleylamine (OLA) capped nickel oxide (NiO) nanoparticles (oleylamine–amine group) onto the acid functionalized multiwalled carbon nanotubes (MWCNTs) (–COOH group) through coulombic interaction, leads to the construction of OLA–NiO/MWCNTs nanocomposite. The optimum loading of OLA–NiO nanoparticles on to the acid functionalized MWCNTs is investigated by Fourier transform infrared spectroscopy. Moreover, the optimum amount of loading and stability of the modified electrodes were studied by using linear sweep voltammetry and conductivity of optimum loadings are also studied by electrochemical impedance spectroscopy. OLA–NiO/MWCNTs nanocomposite was fabricated on glassy carbon electrode for the electrochemical determination of riboflavin (RF) at nanomolar levels. The results show a dynamic linear range of 0.009–55.9 μM with excellent sensitivity of 0.489 μA μM−1 and the limit of detection was found to be 1 nM (S/N = 3). The developed OLA–NiO/MWCNTs composite decorated GC exhibited good sensitivity, stability, and reproducibility for the determination of RF in differential pulse voltammetry. The OLA–NiO/MWCNTs/GC modified electrode was applied for the determination of RF in pharmaceutical formulation tablet and syrup samples.
The relations between the fluorescence and absorption properties of organic molecules

Measurements have been made of the fluorescence spectra, lifetimes and quantum efficiencies and of the absorption spectra of several organic molecules in dilute solution. These have been used to test the validity of the theoretical relation between the radiative lifetime and the absorption intensity, and of the mirror-image relation between the fluorescence and absorption spectra. The former is found to be valid provided there is no major change in the nuclear configuration between the ground and excited states, but the latter is usually more sensitive to such changes. The effect of a change in nuclear configuration, which is particularly marked in the higher diphenylpolyenes, is to increase the radiative lifetime and to distort the spectral intensity distribution.
From polymer–metal complex framework to 3D architectures: growth, characterization and formation mechanism of micrometer-sized α-NiS

A complex-ion reaction route under solvothermal conditions was investigated for the preparation of micrometer-sized NiAs-type α-NiS with complex architectures, on the basis of the strategy that the framework structure of PEG-NiCl2 complex could provide orientation for the growth of 3D NiAs-type α-NiS crystals. The as-prepared NiS powders with flower-like architectures were characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (FE-SEM), ultraviolet, visible light (UV-Vis) and photoluminescence (PL) spectra. Fourier transform infrared absorption (FT-IR) spectra as functions of temperature were recorded to investigate the coordinative chemical effect in the PEG–NiCl2 complex. When PEG-6000 was substituted with poly(vinyl alcohol) (PVA) or poly(vinyl pyrrolidone) (PVP), two other complex architectures (i.e. tennis-ball shaped or urchin-like) were produced. On the basis of a series of supplementary experiments and the result of FT-IR spectra, it was found that both the framework structure of the polymer–metal complex and the functional groups on the polymers had a considerable effect on the final architectures of α-NiS crystals.
Semidilute Polymer Solutions at Equilibrium and under Shear Flow

The properties of semidilute polymer solutions are investigated at equilibrium and under shear flow by mesoscale simulations, which combine molecular dynamics simulations and the multiparticle collision dynamics approach. In semidilute solution, intermolecular hydrodynamic and excluded volume interactions become increasingly important due to the presence of polymer overlap. At equilibrium, the dependence of the radius of gyration, the structure factor, and the zero-shear viscosity on the polymer concentration is determined and found to be in good agreement with scaling predictions. In shear flow, the polymer alignment and deformation are calculated as a function of concentration. Shear thinning, which is related to flow alignment and finite polymer extensibility, is characterized by the shear viscosity and the normal stress coefficients.
Novel pH responsive hydrogels for controlled cell adhesion and triggered surface detachment

In the field of tissue engineering, the development of novel switchable cell growth scaffolds and triggered substrate surfaces is desirable for manipulating detachment of cells. In this paper, two kinds of pH-responsive C2-cyclohexane based cell scaffold biomaterials (G1 and G2) have been designed and synthesized. The highlight is that they can induce detachment of cells from material's surface by slightly reducing the pH of culture medium in an acceptable range. The abilities to culture cells on hydrogel scaffolds and guide cells to detach without proteolytic enzyme treatment are very useful for their development in various biomedical applications.
Synthesis and in vitro evaluation of thiolated chitosan-dextran sulfate nanoparticles for the delivery of letrozole

The main objectives of our study were to prepare and evaluate a biodegradable nanoparticulate system of Letrozole (LTZ) intended for breast cancer therapy. LTZ loaded thiolated chitosan (TCS)-dextran sulfate (DS) nanoparticles were prepared by emulsion - solvent evaporation method. LTZ loaded TCS-DS nanoaprticles were characterized by infrared spectra, drug entrapment efficiency and in vitro release. The system sustained release of LTZ significantly and further investigation could exhibit its potential usefulness in breast cancer therapy. The nanoparticles of LTZ prepared from TCS-DS may represent a useful approach for targeting its release at its site of absorption, sustaining its release. The TCS-DS nanoparticles developed based on the modulation of charge ratio showed promise as a system for controlled delivery of both small and large molecules.
A comparison of dry combustion and acid digestion for the determination of nitrogen in soil and plant material

Abstract A comparison was made between dry combustion in a Leco NP‐28 nitrogen and protein determinator, and acid digestion by the Kjeldahl procedure in the analyses of soil and plant material for total nitrogen. A statistical functional relationship demonstrated that the methods gave results similar in size and reproducibility. Thus the traditional Kjeldahl procedure can be replaced by a simpler and quicker method.
CFD Study of Power and Mixing Time for Paddle Mixing in Unbaffled Vessels

CFD-based computations of the flow field, power consumption and mixing time are presented for a mechanically stirred eight-blade paddle impeller in an unbaffled vessel over a range of Reynolds numbers covering laminar, transitional and turbulent flow regimes. The flow field calculations were performed using the sliding mesh technique to account for the motion of the impeller, and mixing time studies were done using a simulated tracer injection experiment. The effect of grid density and the choice of the turbulence model were investigated. The results are compared with flow field data from Dong et al . 1 , and power and mixing time correlations from the literature and show satisfactory agreement. It is shown that the product of mixing time and rotational speed remains constant for paddle impellers for laminar flow and that the use of a low Reynolds number turbulence model is necessary for good prediction of mixing time in the transitional flow.
Atividade respiratória da microbiota e conteúdo de glicose em resposta à adição de fósforo em solo de Cerrado

Metabolic activity of microorganisms is one of the main processes of control on the nutrient transformation in soil. However, the activity of the soil microbiota is affected by various factors such as the available nutrients, including phosphorus. The present work had as objective to show an approach of the effect of phosphorus addition (50 to 500 mg kg-1 P of dry soil) on the respiratory response of soil microbiota and the amount of extra and intracellular glucose in typic acrustox of Cerrado.The following analyses were carried: amount of C-CO2 evolved; total organic carbon e; extra and intracellular glucose in soil. During the incubation for 31 days, the respiratory activity (daily activity) increased in 6,30 to 23,59 with phosphorus addition, when compared to the control. However, the ratio between the daily carbon evolved (C-CO2) and the added phosphorus decreased, showing a reduction of the efficiency of nutrient utilization. The amount of the extracellular glucose was very smaller than the intracellular glucose. At end of 31 days of incubation, the amount of glucose decreased due to phosphorus addition, showing the consumption of sugar by microorganisms under experimental conditions. Negative metabolic correlation (r= -0.97, p<0.01) between the daily respiration and the intracellular glucose was shown. The soil organic carbon decreased only in the treatment with 500 mg P kg-1of dry soil, being other treatments similar to the control. The strong relation between an increasing of microorganism activity and a decreasing of intracellular glucose occurred, suggesting that the response of soil microbiota to phosphorus addition can be associated to the intracellular glucose content.
Chemistry of soil aluminum

Abstract Better understanding of soil aluminum has had dramatic effects on the interpretation of many aspects of soil chemistry. Aluminum is a Group III element, metallic in nature, and exhibits both ionic and cuvaient bonding. It is the most plentiful of all metallic cations of the earth's crust. It is released from octahedral coordination with oxygen in minerals by weathering processes. Once released, the trivalent Al ion assumes octahedral coordination with six OH2 groups each of which dissociates a H ion in sequence as pH increases. The resulting hydroxy‐Al ions are absorbed to the cation exchange capacity of the soil. Here they polymerize on charged surfaces and in the interlayers of the clay minerals obstructing both the contraction of the clay lattice and the exchange of cations. Soluble Al is toxic to most plants, and reacts readily with soluble phosphates converting them to relatively insoluble and plant‐unavailable forms. Adsorbed and polymerized aluminum affects actual lime requirements of soil.
Solid Sulfur Allotropes

Sulfur is the element with the largest number of solid allotropes. Most of these con- sist of unbranched cyclic molecules with ring sizes ranging from 6 to 20. In addition, poly- meric allotropes are known which are believed to consist of chains in a random coil or heli- cal conformation. Furthermore, several high-pressure allotropes have been characterized. In this chapter the preparation, crystal structures, physical properties and analysis of these allotropes are discussed. Ab initio MO calculations revealed the existence of isomeric sulfur rings with partly rather unusual structures at high temperatures.
Proton transfer in electrode reactions. Experimental test of two theoretical models

All the experimental data on the kinetics of the cathodic discharge of proton donors allowing a choice to be made between two models of an elementary act of proton transfer, the bond-stretching model and the medium-reorganization model, are considered. The specific features of electrochemical processes allowing investigation of the influence of certain factors which cannot be examined by the methods based on the kinetics of homogeneous chemical reactions are discussed. The data concerning barrierless discharge, the influence of the nature of the electrode metal on the preexponential factor and the kinetic isotopic effect, the influence of potential on the isotopic effect during the discharge of H3O+ and H2O, the influence of the nature of the solvent and bond breaking on the activation energy, etc., are analysed. All the experimentally observed relationships are at variance with the conclusions of the bond-stretching model and in full agreement with the predictions of the medium-reorganization model.
Irreversible Statistical Mechanics of Polymer Chains. II. Viscosity

The Fokker–Planck diffusion equation derived in the previous paper is applied to Erpenbeck–Kirkwood theory on the viscosity of polymer solutions. The Newtonian viscosity for ring polymers is given by ηN = 2ckT ∑ σ = 1N τσ / (1 + iωτσ), where τσ is the relaxation time, c is the number of polymers in unit volume, and kT has the usual meaning. Without hydrodynamic interactions among monomer units, the relaxation time is given by τσ = γσ2 / 2Dσ, where γσ and Dσ are, respectively, the expansion parameter and the diffusion constant in regard to the normal coordinate Qσ. With hydrodynamic interactions, the relaxation time is modified as τσ′ = τσ(1 + kTTσ / Dσ), where Tσ is the σth eigenvalue of Kirkwood–Riseman tensor.
Novel pH-sensitive hydrogels of segmented poly(amine ureas) having a repetitive array of polar and apolar units in the main chain

The pH-responsive swelling/deswelling of novel segmented poly(amine ureas) (SPAU) with a repetitive array of polar (N,N'-diethylethylenediamine) and apolar (diethylenephenylene) units in the main chain was examined as a function of ionic strength and temperature. An end-isocyanated polyamine was prepared by the 2:1 addition reaction of 4,4'-methylenediphenyldiisocyanate (MDI) to telechelic polyamine having secondary amino groups at both ends. The isocyanated polyamine was extended by the reaction with equimolar ethylenediamine to form a segmented poly(amine urea) (SPAU). The SPAU exhibited reproducible swelling/deswelling in response to pH changes. A discontinuous 270-fold change in the swelling degree was observed at a critical pH, indicating a phase transition. The shift of ethylenediamine units to the trans conformation on double protonation may play a role in the swelling transition through a stiffening of the polymer strands. The hysteresis observed in the swelling/deswelling cycle in water at 30 o C disappeared upon addition of 0.05 M NaCl or upon lowering of the temperature to 4 o C. The regulation of solute transport across the SPAU matrix responding to a change in external pH was demonstrated using vitamin B 12 as a model solute, suggesting the formation of a barrier layer at the surface of the film that stopped solute diffusion at high pH. SPAUs can be cast on substrates of any shape, providing mechanically strong pH-responsive surface coatings
Catalytic Wet Peroxide Oxidation of Epoxy Resin Wastewater for Reusing

To remove the organic compounds from epoxy resin wastewater which contains high concentration sodium chloride, a catalytic wet peroxide oxidation (CWPO) process was applied to treat it. The effect of different reaction conditions on total organic carbon (TOC) removal efficiency was evaluated, and the experimental results showed that the optimal H2O2 dosage, Fe2+ dosage, temperature, and pH were 0.735 M, 0.027 M, 90oC and 3.0, respectively. Multiple additive methods of H2O2 and Fe2+ significantly enhanced TOC removal than the one step addition. The TOC value of treated wastewater was lower than its limit for diaphragm electrolytic cell feed, thus it could be recycled to a chloro-alkali process for reusing.
Formation and Characterization of Monolithic Nanoporous Copper by Chemical Dealloying of Al−Cu Alloys

Monolithic nanoporous copper (NPC) ribbons can be fabricated through chemical dealloying of melt-spun Al−Cu alloys with 33−50 at % Cu under free corrosion conditions. The microstructure of these NPC ribbons was characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and transmission electron microscopy. The experimental results show that the melt-spun Al−Cu alloys with 33−50 at % Cu are composed of one or a combination of Al2Cu and AlCu intermetallic compounds. Both Al2Cu and AlCu can be fully dealloyed, and the synergetic dealloying of Al2Cu and AlCu in the two-phase Al−Cu alloys results in the formation of NPC with a homogeneous porous structure. The NPC ribbons exhibit an open, bicontinuous interpenetrating ligament-channel structure. NPC is a promising high strength/low density material due to its high porosity and yield strength of 86 ± 10 MPa. In addition, bulk NPC rods and slices can also be synthesized using the same strategy. These NPC ribbons, rods,.
{111} Facet Formation during Lateral Solid-Phase Epitaxy of Silicon

A model for {111} facet formation during lateral solid-phase epitaxy (L-SPE) along the <100> direction has been proposed. Based on the experimental fact that the SPE growth rate along the <110> direction is higher than the <111> direction by a factor of seven, it is concluded that, at the very base of a V-shaped SPE front delineated by {111} facets, SPE takes place predominantly along the <110> direction unless there are obstacles. This would eventually bury the V-shaped valley and the flat {110} facet would be resumed. In order to match this view with the well-known fact that the flat {110} facets never recover once the folded {111} facets are formed, we must assume that there are some obstacles which cause and sustain the folded {111} facets. Via plan-view transmission electron microscopy (TEM) observation we have found that the obstacle is the polygrains which have grown randomly in the amorphous Si region due to heterogeneous nucleation.
Quantitative study of the charge transfer in chemisorption; oxygen chemisorption on ZnO

A new experimental approach is presented for studying the charge‐transfer process involved in the chemisorption on polar semiconductors. This approach utilizes the surface piezoelectric effect, contact potential difference measurements, and surface photovoltage spectroscopy. From the study of oxygen adsorption on ZnO it was found that the rate of electron transfer varies exponentially with the surface barrier height and is proportional to the oxygen pressure (from 10−3 to 20 Torr). Furthermore, it was found that the charge transfer is characterized by a thermal activation energy of about 0.72 eV. At room temperature this activation energy constitutes the most significant rate‐limiting factor and is largely responsible for the extremely slow rate of chemisorption. A model for chemisorption was developed in which the thermal activation is treated as an intermediate nonelectronic step involving metastable activated surface states. Upon capturing electrons from the bulk these states become stable surface stat.
GAMMA AND PROTON IRRADIATION EFFECTS ON OPTICAL TRANSMISSION MATERIALS FOR PLASMA DIAGNOSTICS IN NUCLEAR FUSION REACTOR

Optical transmission materials will play v ery important roles in fusion reactors, where they will be used un der heavy irradiation environments. Our goal is to assess the suitability of SiO2 and Al2O3 based materials for both diagnostic and remote handling application, focusing on comparison of the ionization and displacement induced damage (influence on the UV and visible optical transmission properties). The irradiation facilities are: IRASM ‐ 200 kCi 60 Co source, minimum 2kGy/h, ethanol chlorine benzene and ESR dosimetry; HVEC 8 MV TANDEM ‐ protons up to 16 MeV and 200 nA. The gamma and proton irradiation chambers characteristics and some preliminary results on alumina pellets are presented.
Analysis of Success in General Chemistry Based on Diagnostic Testing Using Logistic Regression

Several chemistry diagnostic and placement exams are used to help place chemistry students in an appropriate course or to determine strengths and weaknesses for specific topics in chemistry or math. The purpose of obtaining pre-course measurements is to increase students' academic success. Often these tests are used to predict the chance a student has in passing a course. This paper discusses the statistical methods of logistic regression applied to predicting the probability of passing a course, based on the scores on the California Chemistry Diagnostic Test at two different institutions with two different instructors over multiple years. This technique describes the relation of a test score (a continuous variable) to the probability of passing the class (a binary variable). Many papers in the Journal of Chemical Education have used a simple linear regression technique to correlate placement test scores with the proportion of students passing a course. The model assumptions are difficult to satisfy when using simple linear regression. Simple linear regression is useful when continuous predictor variables predict a continuous response, whereas logistic regression is useful when continuous predictor variables predict a binary response. Differences between simple linear regression and logistic regression and methods for evaluating linear regression model assumptions are discussed in detail. The fundamental concepts behind regression are described, with the caveats of using regression equations for predictions. By using logistic regression, instructors will be able to provide students with an estimate of their probability of passing the course.