Miracle-dz/UniFAR-FTUs huggingface dataset:
Response of an Iridium Oxide pH-Sensor in Nonaqueous Solutions. Comparison with Other pH-Sensors

The response of an iridium oxide (IrO_2) pH-sensor (nonaqueous version of METOX, TOA Electronics Ltd.) was studied in various dipolar aprotic solvents. From the potential measurements in picric acid-picrate solutions, it was confirmed to respond in a Nernstian way to the pH in all the solvents studied. The response speed of the IrCh pH-sensor was compared with that of the glass electrode as well as those of the Si_3N_4- and Ta_2O_5-type pH-ISFETs, carrying out acid-base titrations at various speeds of titrant addition. The response speed of the IrO_2 pH-sensor was much higher than that of the glass electrode, though it was somewhat lower than those of the pH-ISFETs. The IrO_2 pH-sensor responded in a wide pH range, gave reproducible results, needed no pretreatment, and was durable over a year. It is promising for pH measurements in various nonaqueous solutions free from redox systems.
Lattice compression and structural behavior of NaVSi2O6 clinopyroxene to 11 GPa

Abstract High-pressure behavior of a synthetic single crystal of the C2/c clinopyroxene NaVSi2O6 was investigated using X-ray diffraction and Raman spectroscopy in combination with diamond-anvil cell techniques. Lattice-parameters, single-crystal intensity data, and Raman spectra were collected up to pressures of about 11 GPa, revealing no discontinuity in the evolution of the lattice with increasing pressure. The fit of a third-order Birch-Murnaghan equation of state to the pressure-volume data yields a bulk modulus of K0 = 114.7 (1.8) GPa with its pressure derivative K′ = 5.4 (4). Strain analysis reveals compressional anisotropy with unit strain axial ratios of 1:2.9:3.1. The direction of largest compression was found to be perpendicular to the (3̅02) plane, which matches closely the direction of largest interlayer spacing between oxygen monolayers forming the structure of clinopyroxenes. The relatively large pressure dependency of the bulk modulus, compared to that of isostructural transition-metal compounds, was related to an increase in stiffness of the M2 polyhedron occurring above 4.6 GPa.
Theoretical Simulation of Temperature Programmed Desorption of Molecular Oxygen on Isolated Au Nanoparticles from Density Functional Calculations and Microkinetics Models

A microkinetic model has been developed to describe the evolution of atomic and molecular oxygen on a variety of Au nanoparticles with rate constants derived from density functional calculations. Simulated thermal programmed desorption (TPD) curves are also presented and compared with recent experimental results for Au nanoparticles supported on silica. The present calculations confirm that TPD temperature peaks depend on the particle size, in agreement with experiment, and provide some clues about the chemical composition of the particles used in the experiments.
The Behaviour of Pure Titanium in Albumin Solution

Among the different biofluids in the human body, albumin is the most important plasma proteins circulating in the bloodstream and our paper are focused on the behaviorof pure titanium in albumin solution. The samples investigated were immersed for 10 days in a mixture of human body plasma and bovine serum albumin solution with concentrations of 2% and 10% in weight. The analysis by diffuse reflectance in the 220–2300 nm domain, and in the mid-infrared range (400–4000 cm−1) was performed. The albumin adsorption at interface was put in evidence from spectral data and is found to be most important in the sample containing a higher concentration of albumin, regarding the relative band intensity. This is in agreement with the electrochemical results showing a better stability at a smaller albumin concentration according to a higher corrosion rate.
Electronic and optical properties of silole‐based derivatives

Purpose – The purpose of this paper is to focus on the development of highly efficient emission materials for light‐emitting diodes (LEDs). Design/methodology/approach – The equilibrium geometries of silole‐based derivatives are optimised by means of DFT/B3LYP method with the 6‐31G(d) basis set in this paper. The geometries of single‐excitation are optimised using the ab initio configuration interaction with single excitations/6‐31G(d), the first singlet excited states and optical properties are calculated by using time‐dependent density‐functional theory based on the 6‐31G(d) basis set.Findings – The highest occupied molecular orbital and lowest unoccupied molecular orbital suffer larger effects from the variation of the substituent groups of methyls and phenyls. The absorption wavelengths of all the cases are similar, but the emission wavelengths are significantly different.Research limitations/implications – Solid‐state stacking effect is not included in this paper.Originality/value – In view of the app.
Effect of temperature and nitrogen source on nitrification in a sandy soil

The effect of soil temperature, nitrogen (N) source, and indirectly soil pH, on the nitrification of 15NH4-N, was studied in a sandy, moderately acidic soil. Four N sources, including a 15N-labeled urea solution and mixtures of a 15N-labeled urea and a HNO3-N solution were added to soil which was incubated at 20°C, 16°C, 12°C, 10°C, 8°C, and 5°C. The N sources adjusted the soil pH to 8.3, 7.1, 6.7, and 5.4 within 4 days of application. These treatments enabled an evaluation of the interactions between soil pH and temperature as they affect nitrification in sandy soil. The content of 15NH4-ions and 15NO3-ions in 1 M KCl extracts was determined by steam distillation and mass spectrometry. Maximum rates of nitrification decreased as temperature was reduced from 20°C to 5°C and as the input of alkalinity in the N sources declined. The relationships between temperature and relative maximum rates of nitrification (rrel) were best described by the Arrhenius equation. However, the temperature coefficient, or Q10, determined from the fitted Arrhenius equation was ∼5, a value which is higher than that typically used to describe the effect of temperature on nitrification. The production of NO3-ions after 56 days declined as soil temperature was reduced from 20°C to 5°C. Nitrification was limited by pH in soil treatments which were amended with urea and incubated at 20°C. In contrast, nitrification ceased at soil pH 5.0, 5.8, and 6.3 when soil amended with urea was incubated at temperatures of 16°C, 12°C, and 10°C, respectively. Nitrite (NO2-ion) was found to accumulate in urea-amended soil incubated at temperatures below 12°C, implying that the growth and activity of nitrite oxidizing bacteria were preferentially restricted at temperatures below 12°C. The peak concentrations of NO2-ions preceded the inhibition of nitrification at pH 5.8 and pH 6.3 in soil incubated at 12°C and 10°C, respectively. These findings suggest that nitrification is not always limited by the growth and activity of NH4-ion oxidizers as has been often assumed in models of nitrification.
Carbon isotopes of water‐extractable organic carbon in a depth profile of forest soil imply a dynamic relationship with soil carbon

Although considerable research has been conducted on the importance of recent litter compared with older soil organic matter as sources of dissolved organic carbon (DOC) in forest soils, a more thorough evaluation of this mechanism is necessary. We studied water‐extractable organic carbon (WEOC) in a soil profile under a cool‐temperate beech forest by analysing the isotopic composition (13C and 14C) of WEOC and its fractions after separation on a DAX‐8 resin. With depth, WEOC became more enriched in 13C, which reflects the increasing proportion of the hydrophilic, isotopically heavier fraction. The 14C content in WEOC and its fractions decreased with depth, paralleling the 14C trend in soil organic matter (SOM). These results indicate a dynamic equilibrium of WEOC and soil organic carbon. The dominant process maintaining the WEOC pool in the mineral soil appears to be the microbial release of water‐soluble compounds from the SOM, which alters in time‐scales of decades to centuries.
High thermal conductivity graphite nanoplatelet/UHMWPE nanocomposites

High thermal conductivity graphite nanoplatelet/ultra-high molecular weight polyethylene (GNPs/UHMWPE) nanocomposites are fabricated via mechanical ball milling followed by a hot-pressing method. The GNPs are located at the interface of the UHMWPE matrix. The thermal conductivity coefficient of the GNPs/UHMWPE nanocomposite is greatly improved to 4.624 W m−1 K−1 with 21.4 vol% GNPs, 9 times higher than that of the original UHMWPE matrix. The significantly high improvement of the thermal conductivity is ascribed to the formation of multidimensional thermally conductive GNPs–GNPs networks, and the GNPs have a strong ability to form continuous thermally conductive networks. The method of cooling-pressing on the machine is more beneficial for the improvement of the thermal conductivity, by increasing the crystallinity of the UHMWPE matrix. Furthermore, the thermal stabilities of the GNPs/UHMWPE nanocomposites are increased with increasing addition of GNPs.
Extraction of Ashwagandha by conventional extraction methods and evaluation of its anti-stress activity.

The present study was conducted to compare the yield and the antistress activity of Ashwagandha (Withania somnifera) extracts, using two extraction methods: hot continuous percolation and maceration. Various parameters like temperature, extraction time (10 hours) solvents (water, alcohol, hydroalcohol) and drug-solvent ratios (1:6, 1:8, 1:10) were fixed. The highest yield was found to be 16.96% w/w by maceration process using water (1:8). The activity of different extracts was done by Plus-Maze model using alprazolam as the standard drug. Significant result was found in water extract and hydroalcoholic (1:8) extract prepared by maceration method and also in hydro-alcoholic extract (1:8) prepared by soxhlet process. Key words: Alprazolam, anti-stress activity, elevated plus maze, extraction, withania somnifera
The dipole moment function and vibrational transition intensities of OH

The relative intensities of nine pairs of rovibrational transitions of OH in the v=1←0 fundamental have been measured by flash kinetic infrared absorption spectroscopy. Each pair of transitions originates from a common rotational and spin–orbit state, so that relative intensities are independent of the OH number density and quantum state distribution. The relative intensities are strongly J dependent and this dependence provides detailed information about the shape of the OH dipole moment function, μ(r), and hence the absolute infrared transition strengths. In an accompanying paper we present the theoretical basis for extracting μ(r), for an open shell diatomic like OH, from relative infrared intensities and permanent dipole moment measurements (Peterson et al.). In this work we implement those ideas and determine the OH dipole moment function to be: μ(r)=1.6498(6) D+0.561(32) D/A (r−re )−0.75(17) D/A2 (r−re )−1.5(11) D/A3(r−re )3. The accuracy of μ(r) is excellent near re (re =0.970 A), since the data us.
Nonlinear Model Predictive Control: A Self-Adaptive Approach

Model predictive control (MPC) is an online application based on dynamic models. Its application faces two major obstacles: (i) computational constraints and (ii) the need to accurately simulate the process by a model that properly predicts how the plant will behave in the future.Implementation of MPC is not always possible in large-scale or industrial applications due to the computational complexity of MPC and to the dimensionality of the models. To facilitate MPC implementations, this paper proposes a self-adaptive approach based on simplified (or reduced-order) nonlinear models. The proposed methodology yields an MPC that adjusts the dimension of the model according to both the current process conditions and the control objectives. The self-adaptive approach is described and validated on an industrial case study, a C4-splitter.
Assessing the impact of crops on regional CO2 fluxes and atmospheric concentrations

Human conversion of natural ecosystems to croplands modifies not only the exchange of water and energy between the surface and the atmosphere, but also carbon fluxes. To investigate the impacts of crops on carbon fluxes and resulting atmospheric CO2 concentrations in the mid-continent region of the United States, we coupled a crop-specific phenology and physiology scheme for corn, soybean and wheat to the coupled ecosystem–atmosphere model SiB3–RAMS. Using SiBcrop–RAMS improved carbon fluxes at the local scale and had regional impacts, decreasing the spring uptake and increasing the summer uptake over the mid-continent. The altered fluxes changed the mid-continent atmospheric CO2 concentration field at 120 m compared to simulations without crops: concentrations increased in May and decreased >20 ppm during July and August, summer diurnal cycle amplitudes increased, synoptic variability correlations improved and the gradient across the mid-continent region increased. These effects combined to reduce the squared differences between the model and high-precision tower CO2 concentrations by 20%. Synoptic transport of the large-scale N–S gradient caused significant day-to-day variability in concentration differences measured between the towers. This simulation study shows that carbon exchange between crops and the atmosphere significantly impacts regional CO2 fluxes and concentrations.
Poly(methyl methacrylate)/Laponite Nanocomposites: Exploring Covalent and Ionic Clay Modifications

Laponite clay was modified with combinations of organic ammonium surfactant and/or covalently bound poly(methyl methacrylate) (PMMA). Two polymer attachment methods were explored, one through reaction of a methacrylate compound with the clay's silanol group followed by in situ free-radical polymerization of methyl methacrylate (MMA), and the other through attachment of an ATRP initiator followed by brush polymerization. The free-radical method yielded clays with ca. 75 wt % of polymer bound though multiple attachment sites to the clay, whereas the ATRP method yielded ca. 68 wt % of bound polymer attached only at the chain end. The PMMA-modified clays were very dispersible in organic solvents and were solvent-blended with commercial PMMA at 1, 3, 5, and 10 wt % concentrations. The resulting nanocomposites were optically transparent and homogeneous. TEM images showed mixed intercalated and exfoliated dispersions. DMA analysis showed an increase in room temperature modulus of 50% at 5 wt % concentration for .
Synthesis and characterization of new soluble polyamides derived from 2,6‐bis(4‐aminophenyl)‐3,5‐dimethyltetrahydro‐4H‐pyran‐4‐one

A new oxypyrone diamine, 2,6-bis(4-aminophenyl)-3,5-dimethyltetrahydro-4H-pyran-4-one (DAPP), was prepared from 4-nitrobenzaldehyde and 3-oxa-n-pentane in a two-step reaction with a high yield and a high purity. Aromatic polyamides were obtained from this novel condensation monomer and several diacid chlorides through the conventional low-temperature solution method in N,N-dimethylacetamide. Polycondensation results were consistent with a high reactivity for DAPP because high yields and high molecular weight polyamides were obtained with inherent viscosities up to 1.8 dL/g. The reactivity of DAPP was also estimated with theoretical calculations from computer programs for molecular simulation, with orbital and charge factors considered. The polymers showed improved solubility in organic solvents, relative to conventional wholly aromatic polyamides, and high glass-transition temperatures (from differential scanning calorimetry) over 270 °C. However, the thermal resistance, as estimated by thermogravimetric analysis, was lower than that of conventional aromatic polyamides; nevertheless, decomposition temperatures well beyond 300 °C were observed in nitrogen and air. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1825–1832, 2001
The specific surface of powders. A modification of the theory of the air‐permeability method

The paper describes a modification of the Kozeny theory of the air-permeability method for determining the specific surface of powders to take into account the effect of “slip” at the walls of the pores in the bed of powder. The dependence of the measured value of specific surface on the mean pressure in the bed has been examined experimentally, and it is shown that, by making the correction for “slip,” values of specific surface are obtained substantially independent of the mean pressure (and hence of the mean free path of the gas molecules) in the region of atmospheric pressure. It is also shown that, if the modified equation is used, good agreement is obtained between values of specific surface determined by the “air” method and by a “liquid” method using water, acetone or n-hexane. A full account is given of the experimental work which has included measurements on six powders ranging in surface area from 0·4 to 5 sq. metre/g.
Direct Measurements of the Isotope Exchange Reactions between 18OH and NO, NO2, N2O and O2

The isotope exchange reactions between 18OH and NO, NO2, N2O and O2 were studied at room temperature in a discharge flow system with laser magnetic resonance detection of 18OH and 16OH. Exchange rate constants of where obtained for NO and NO2, respectively. Upper limits of k < 1 · 108 cm3/mol s can be reported for the reactions The results are compared with recombination rate data in the limit of high pressures and with vibrational deactivation measurements.
Silica nanoparticles functionalized with porphyrins and analogs for biomedical studies

This review focus on the preparation of silica nanoparticles functionalized with porphyrins and related compounds. It is aimed to highlight their features as photosensitizers in the area of photodynamic therapy. In this field, photosensitizers have been covalently and non-covalently linked to silica nanoparticles, in order to study their photophysical and biological properties. Another fascinating scenario for photosensitizer-silica nanoparticles hybrids involves the possibility of including metal cores for conditioning the uptake in the target cells, allowing most of the times the combination of therapies and in certain conditions to facilitate the removal and reutilization of the photosensitizer in environmental applications.
A simultaneous assay method using capillary zone electrophoresis for a fixed dose combination of vildagliptin and metformin hydrochloride in coated tablets

In the present study, a quick and reliable validated capillary zone electrophoresis (CZE) method was established for the simultaneous determination of vildagliptin (VLG) and metformin hydrochloride (MET) in pharmaceutical dosage form. Successful separation of the drugs by the CZE method was achieved in a fused silica capillary by applying a potential of 25 kV (positive polarity) and hydrodynamic injection by 50 mbar for 5 s. The selected running buffer consisted of 25 mM sodium tetraborate decahydrate solution (array pH 9.0) with UV/photodiode (PDA) detection at 207 nm and 250 nm for VLG and MET respectively. Specificity, linearity, precision, accuracy, limit of detection and limit of quantitation and robustness were established for VLG and MET in accordance with International Conference on Harmonization (ICH) guidelines. The specificity and stability-indicating capability of the method was established by enforced degradation studies combined with peak purity assessment using PDA detection. Electrophoretic separation was obtained within 10 min and the method was linear in the range of 30–60 μg mL−1 and 300–600 μg mL−1 for VLG and MET, respectively (R2 > 0.9980). Precision of the method was reflected by RSD lower than 2.95% and accuracy results around 100% for both VLG and MET measurement. Moreover, the Plackett–Burman experimental design was used to evaluate robustness, producing results within the acceptable range.
Heterogeneous Uptake Kinetics of Volatile Organic Compounds on Oxide Surfaces Using a Knudsen Cell Reactor: Adsorption of Acetic Acid, Formaldehyde, and Methanol on α-Fe2O3, α-Al2O3, and SiO2

The role of heterogeneous reactions on particulate matter present in the Earth's atmosphere remains an important question in tropospheric chemistry. It has been proposed in several modeling studies that mineral dust may provide reactive surfaces for trace atmospheric gases. Laboratory studies can provide some answers concerning the kinetics of these reactions, so that heterogeneous chemistry can be quantitatively assessed in atmospheric chemistry models. In this study, the heterogeneous uptake kinetics of several volatile organic compounds (VOCs) on oxide surfaces have been measured with a Knudsen cell reactor at 295 K. In particular, the heterogeneous uptake of acetic acid, methanol, and formaldehyde on α-Fe2O3, α-Al2O2, and SiO2 has been investigated. These VOCs are representative of some of the different types of oxygenated organics found in the atmosphere. The oxide particles used in this study are models for mineral dust found in the Earth's atmosphere. Initial uptake coefficients, γ0, have been extr.
Adsorption Behavior of Chlorophenols on Natural Zeolite

Abstract The adsorption of aqueous organic pollutants, i.e., phenol, monochlorophenols (2‐and 4‐), and dichlorophenols (2,4‐and 3,5‐) on natural Jordanian zeolitic tuff was studied. Three simplified kinetic models, viz., pseudo‐first order, pseudo‐second order, and intraparticle diffusion models were used to fit the kinetics data. The results revealed that at earlier stages of adsorption of phenols onto zeolite, the pseudo‐second order and the bulk diffusion rate constants are dependent on the acidity and the hydrophobicity of phenols. Whereas at later stages of adsorption, the adsorption capacity and the intraparticle diffusion rate constants are affected by the molecular size and the extent of dissociation of phenols.
Scientific Inquiry: A Bridge.

This paper outlines a three semester hour undergraduate, core course in Scientific Inquiry that increases student knowledge and advances student skills in understanding science as knowledge, process, and human enterprise. This course was developed as a bridge between science and the humanities and a bridge for entry-level students in the development of attitudes and understandings of methods used in scientific research and enterprise. The sample for the study was 54 undergraduate college students in a private urban Catholic 4-year college with an enrollment of 2,700 students. In comparing the pretest and posttest survey, student beliefs about science were still localized around content or "body of knowledge. " Surprisingly, students views moved away from the process view "exploring the world. " (PR) *********************************************************************** * Reproductions supplied by EDRS are the best that can be made * * from the original document. * *********************************************************************** Scientific Inquiry : A Bridge Carolyn B. Black, PhD Incarnate Word College San Antonio, TX 78209 A paper presented at the annual meeting of the National Association for Research in Science Teaching, April 16, 1993, Atlanta, GA. U.S. DEPARTMENT OF EDUCATION ) Ottote of Educational Reseatch and improvement EDUCATIONAL RESOURCES INFORMATION CENTER (ERIC) EXThis document has been reproduced as received from the person or oroaniztion 1 Ofiginahng it 0 Minor changes have boon made to improve reproduction quality Points ot view Of OpiniOns stated in this document do not necessarily represent official OEM POsitrOn of policy "PERMISSION TO REPRODUCE THIS MATERIAL HAS BEEN GRANTED BY Carolyn B. Black TO THE EDUCATIONAL RESOURCES INFORMATION CENTER (ERIC). " Running head: Scientific Inquiry: A Bridge