Miracle-dz/UniFAR-FTUs huggingface dataset:
Photoelastic constants in diamond and silicon

Ab Initio calculations, using density functional theory within the AIMPRO code, have been performed on bulk diamond and silicon in order to calculate the change in the dielectric constant due to strain, and hence the values of the photoelastic tensors. A combination of compressive and tensile strain has been applied to two atom unit cells of Si and diamond and the tensors relating to p 11 + 2p 12, p 12 – 2p 11 and p 44 extracted. Good agreement is found with experimental results for absolute values and frequency dependence of the constants for silicon. Results are also given for diamond where experimental data is much more limited and scattered. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Facile synthesis of rGO/SnO2 composite anodes for lithium ion batteries

The reduced graphene oxide/SnO2 (rGO/SnO2) composite was facilely synthesized via a modified colloidal coagulation method and a subsequent reduction. As an anode for lithium ion batteries, it delivers a high reversible capacity of 795 mA h g(-1) in the 600th cycle at a current density of 1000 mA g(-1). The excellent electrochemical performances are mainly due to its morphology stability and the reversible reaction between the formed Li2O and Sn to yield SnO2, as confirmed by XPS and TEM characterization after 200 cycles.
Hydrodynamical Dispersion in Taylor-Couette Cells

In this article we study the mass tracer dispersion in organized flows For this purpose we performed experiments in the flow arising from the Taylor-Couette hydrodynamic instability combined with axial flow. The tracer evolution is followed by means of optical mea- surements of the concentration. In this way transmission curves are obtained. We compare these curves with the solutions of the Gaussian models of mass diffusion and with phenomenological models including tracer trapping in the cells. This comparison gives us physical parameters related to the typical time and distances involved in the diffusive behaviour of tracers in the regions with recirculations and trapping.
X‐Ray Structural Studies of Highly Enantioselective Mn(salen) Epoxidation Catalysts

The relationship between catalyst structure and enantioselectivity in the asymmetric epoxidation of unfunctionalized olefins by a series of chiral Mn(sa1en) complexes (1 – 10) was examined. The X-ray structures of 5-coordinate complexes 5, 8, of 6-coordinate 9 ([6,6′= -tBu; 4,4 = -tBu]+ClO4−), and 10 (6,6′= -tBu; 4,4′=-Br) were determined. Catalysts 1 – 9 were derived from (R,R)-1, 2 diaminocyclohexane and catalyst 10 from (S,S)-1,2-diphenylethylenediamine. Catalysts 1–9 differ in the stereoelectronic substitution of the ortho (6,6) and para (4,4) positions of the salicylidene moiety. A comparison between structures 5, 8, and 9 reveals that the ligand geometry around the metal center and the chiral diimine backbone remains remarkably constant in both five- and six-coordinate cyclohexanediamine-derived complexes; in contrast, the salicylidene regions of the complexes display a wide range of conformations. The asymmetric epoxidation of indene and 6-cyano-2,2-dimethylchromene with NaOCl catalyzed by complexes 1 – 10 was effected. Systematically increasing the steric bulk on the ortho and then the para position in the order 1 (6,6′ = -H; 4,4′ = -H),2(6,6′ = -CH3; 4,4′ = -CH3),3(6,6′=-tBu;4,4′=-H),4(6,6′=-tBu; 4,4′ =-CH3), 5 (6,6′=-tBu; 4,4′=-tBu), and 6 (6,6′=-tBu; 4,4′= -trityl), and electronically modifying the para substituents in 7 (6,6 = -tBu; 4,4 =-OMe) and 8 (6.6′ = -tBu; 4,4′=-OTIPS) resulted in enhanced enantioselectivities of the desired epoxides. The conformational variations observed in the solid state are likely to reflect accessible solution conformations and may help explain the high levels of stereoinduction obtained with these catalysts in the asymmetric epoxidation of unfunctionalized olefins.
Characterization of Holographic Band-Reject Filters Designed for Raman Spectroscopy

We report the optical transmission properties of holographic band-reject filters designed for Raman spectroscopy using excitation at 514.5 nm and at 632.8 nm. We use these data to quantitatively evaluate the compromise between rejection of elastic scatter and transmission of Raman bands as a function of Raman shift. We demonstrate the use of a single filter for the rejection of elastically scattered light from the Raman spectra of a white powder and of a clear liquid.
Design parameters estimations for bubble column reactors

Gas-liquid as well as gas-liquid-solid bubble column reactors are extensively used in the chemical industry. This review evaluates the present state of the art for the estimation of “nonadjustable” parameters in bubble column reactors. All the pertinent literature concerning these parameters is discussed and the discussion is followed by relevant recommendations for their predictions. Literature on the modified bubble columns has been incorporated. Finally, the inadeqacies of the data in some areas of practical importance have been pointed out and the recommendations for future work are outlined.
Polysaccharide Nanocomposites Reinforced with Graphene Oxide and Keratin-Grafted Graphene Oxide

Nanocomposites of polysaccharide matrices, chitosan–starch, and carboxymethyl cellulose-starch reinforced with graphene oxide and graphene grafted with keratin were developed. Composites films had been prepared for the casting/solvent evaporation method. The interaction and distribution of graphene materials in the biopolymer matrices were analyzed by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM), and the thermomechanical properties were examined using dynamic mechanical analysis. The nanocomposites of the chitosan–starch matrix improved their mechanical properties substantially, with respect to the film without reinforcing, obtaining an increase of 929% in the storage modulus (E′, 35 °C) with only 0.5 wt % of graphene oxide and outstanding increments in E′ at 150 and 200 °C when keratin-grafted graphene oxide is incorporated (0.1 wt %). In contrast, the graphene oxide incorporated into the carboxymethyl cellulose–starch matrix tends to decrease.
Evaluation of the 15Nitrogen Isotope Dilution Technique for Estimating Crop Nitrogen Uptake from Organic Residues

Abstract A field experiment was conducted to test the new approach for estimating crop nitrogen (N) uptake from organic inputs. The soil was prelabeled with 15N by applying 15N fertilizer to sunflower crop (Helianthus annuus L. var. Viki). The 14N plots, which received unlabelled fertilizer, were also set up. At harvest, 15N labeled residues were added to the unlabeled soils at a rate of 73 kg N ha−1 (direct technique) and unlabeled residues were added to the 15N‐labeled soils at the same rate (indirect technique). Control plots without residues were also established. All plots were sown with the wheat (Triticum aestivum L. var merchouch)–fababean (Vicia faba L.)–wheat (Triticum aestivum L. var merchouch) cropping sequence. In the cropping sequence, the first, second and third crop derived respectively 12.01, 2.4, and 1.93 kg N ha−1 from crop residues estimated by the direct method and 14.77, 3.3, and 1.85 kg N ha−1 estimated by the indirect method. The results showed no significant difference between the two techniques, which suggests that the new soil prelabeling technique compares well with the direct technique.
Optimization Study: Biological Removal of Inorganic Nitrogen along with Chemical Oxygen Demand from Wastewater Using Response Surface Methodology

A comparative optimization study using response surface methodology (RSM) was carried out for biological removal of various inorganic N–NH3 sources (NH4OH, (NH4)2SO4, NH4NO3) along with chemical oxygen demand (COD; glucose: C6H12O6) from synthetic wastewater and consequently minimizing the N–N2O emission. Heterotrophic biomass conversion (HBC) process was used for wastewater treatment. Central composite design (CCD) method was used to optimize various experimental parameters using RSM. During the experiment biomass (total volatile suspended solids) was kept constant, while varying nitrogen and carbon concentration, respectively. Alkalinity consumption results in pH decrease during the HBC process. N–NH3 and COD depletion rates were higher in NH4OH in comparison to the other two nitrogen sources. Analyses of variance observed highly significant differences. Models obtained through CCD method were checked and tested via experiments and statistics. Having optimum value, i.e., 210 mg/L N–NH3, 2.90 g/L COD and 38 h; higher COD (94.1%) and N–NH3 (82.72%) removal was observed in (NH4)2SO4 and NH4OH. Higher desirability factor was obtained in NH4OH.
Diffusion-Induced Instabilities near a Canard

We investigate diffusion-induced instabilities of phase waves in one spatial dimension for a two-variable model of the Belousov-Zhabotinsky reaction. We use as initial conditions small-amplitude phase waves which exist in the parametric range between a canard point and a supercritical Hopf bifurcation point. Closer to the canard point, the instability leads to initiation of trigger waves, usually at the zero flux boundary. Such induced trigger waves reflect from the boundary, and when they collide, a new trigger wave emerges at the location of the collision. When the parameters are chosen nearer to the Hopf point, the phase waves lose their regular pattern and become uncorrelated. Very close to the Hopf point, diffusion alters the phase wave profile into small-amplitude synchronized bulk oscillations. Different types of spatiotemporal behavior are observed when the wavelength of the phase waves, the overall size of the system, or the diffusion coefficients are changed. Comparison of the behavior near a canard and near a subcritical Hopf bifurcation shows that in the former case trigger waves can be initiated at all points of the excitable medium, whereas in the latter case trigger waves are generated only at the boundary.
Temperature Dependent Performance and In Situ AC Impedance of High-Temperature PEM Fuel Cells Using the Nafion-112 Membrane

In this paper, temperature dependent performance of a Nafion 112-based proton exchange membrane (PEM) fuel cell was investigated at different temperatures, 30 psig back pressure, and 100% relative humidity (RH). High cell performance of ca. 0.637 V at 1.0 A/cm 2 was obtained at 120°C. Cell voltage decreased when the temperature increased within the range of 80-20°C. An in situ ac impedance spectroscopy method under load was developed to diagnose the performance reduction. A semi-empirical treatment was initiated to obtain expressions for extinguishing the individual performance drops caused by reaction kinetics (charge-transfer resistance), membrane resistance, and mass-transfer limitation, respectively.
Label free Detection of Vitamin B12 Based on Fluorescence Quenching of Graphene Oxide Nanolayer

A graphene oxide nanolayer was synthesized and characterized. The label free detection of vitamin B12 based on fluorescence spectroscopy was investigated. The graphene oxide was shown to specifically interact with vitamin B12 in comparison with other samples including vitamin B1, vitamin B9, vitamin C, vitamin B6, urea, lauric acid, glucose, and uric acid. The quenching effect of B12 on the fluorescence emission of graphene oxide layer based on a Stern–Volmer type equation was used to detect samples. The limit of detection (3.2 × 10−7 M) and limit of quantitation (1.08 × 10−6 M) were obtained under optimal condition.
Neural network potentials for metals and oxides – First applications to copper clusters at zinc oxide

The development of reliable interatomic potentials for large‐scale molecular dynamics (MD) simulations of chemical processes at surfaces and interfaces is a formidable challenge because a wide range of atomic environments and very different types of bonding can be present. In recent years interatomic potentials based on artificial neural networks (NNs) have emerged offering an unbiased approach to the construction of potential energy surfaces (PESs) for systems that are difficult to describe by conventional potentials. Here, we review the basic properties of NN potentials and describe their construction for materials like metals and oxides. The accuracy and efficiency are demonstrated using copper and zinc oxide as benchmark systems. First results for a potential of the combined ternary CuZnO system aiming at the description of oxide‐supported copper clusters are reported.
EDTA: the chelating agent under environmental scrutiny

The chelating agent EDTA (ethylenediaminetetraacetic acid) is a compound of massive use world wide with household and industrial applications, being one of the anthropogenic compounds with highest concentrations in inland European waters. In this review, the applications of EDTA and its behavior once it has been released into the environment are described. At a laboratory scale, degradation of EDTA has been achieved; however, in natural environments studies detect poor biodegradability. It is concluded that EDTA behaves as a persistent substance in the environment and that its contribution to heavy metals bioavailability and remobilization processes in the environment is a major concern.
Nonthermalized excited states in Ru(II) polypyridyl complexes probed by ultrafast transient absorption spectroscopy with high photon energy excitation

The picosecond excited state dynamics of a series of homoleptic Ru(II) polypyridyl complexes (where LL = bpy, dmb, dmeob, dfmb, or dttb) have been investigated in aqueous solution at room temperature using femtosecond transient absorption spectroscopy with high photon energy excitation. All of the complexes studied produced similar spectroscopic signatures: a near-instantaneous bleach centered at 470-500 nm corresponding to the static absorption spectrum, as well as an intense absorption (475-650 nm) that decayed within the instrument response function (IRF) to form a broad, low-level absorption extending from 500-650 nm. Detailed analyses of both kinetic and spectral parame- ters by singular value decomposition (SVD) indicate that the excited state difference spectra contain contributions from at least three distinguishable species that have been assigned as ligand-based π* ←π * and ligand-to-metal-charge- transfer (LMCT) transitions concomitant with the loss of the ground state metal-to-ligand-charge-transfer (MLCT) tran- sition. Kinetic information extracted at 530 nm (an optical marker for the fully intraligand-delocalized 3 MLCT state) or 660 nm (LMCT transitions) appear to be biphasic in some cases with the amplitude of the IRF-limited component be- coming larger with shorter wavelength excitation. Further, rise dynamics were observed at redder probe wavelengths for Ru(bpy)3 2+ and Ru(dttb)3 2+ . These observations are different from those obtained using lower photon energy excitation and show that excitation wavelength strongly influences the early photophysical events in these Ru(II) complexes.
Water oxygen-17 magnetic relaxation in polyelectrolyte solutions

Water oxygen-17 longitudinal and transverse relaxation rates have been measured at two frequencies for aqueous solutions of poly(acrylic acid) and poly(methacrylic acid) under conditions of variable temperature, concentration and degree of dissociation. The proton-exchange broadening of the 17O resonance from these polyacid solutions has also been investigated. The data show that the residence time for water molecules interacting with the polyacid is of the order of 10–8 s, during which time they reorient anisotropically, an order of magnitude slower than bulk water, and engage in rapid proton transfer with acidic groups. The motional perturbation of associated water is to a large extent electrostatically induced. A new method for determining an upper limit for the lifetime of ‘bound’ water from the proton-exchange broadening is employed and the necessary equations are derived.
Wavelength Selection with a View to a Simplified Handheld Optical System to Estimate Grape Ripeness

The aim of this work was to identify the three most significant wavelengths able to discriminate in the field those grapes ready to be harvested using a simplified, handheld, and low-cost optical device. Nondestructive analyses were carried out on a total of 68 samples and 1,360 spectral measurements were made using a portable commercial vis/near-infrared spectrophotometer. Chemometric analyses were performed to extract the maximum useful information from spectral data and to select the most significant wavelengths. Correlations between the spectral data matrix and technological (total soluble solids) and phenolic (polyphenols) parameters were carried out using partial least square (PLS) regression. Standardized regression coefficients of the PLS model were used to select the relevant variables, representing the most useful information of the full spectral region. To support the variable selection, a qualitative evaluation of the average spectra and loading plot, derived from principal component analysis, was considered. The three selected wavelengths were 670 nm, corresponding to the chlorophyll absorption peak, 730 nm, equal to the maximum reflectance peak, and 780 nm, representing the third overtone of OH bond stretching. Principal component analysis and multiple linear regression were applied on the three selected wavelengths in order to verify their effectiveness. Simple equations for total soluble solids and polyphenols prediction were calculated. The results demonstrated the feasibility of a simplified handheld device for ripeness assessment in the field.
Proximate Composition, Colour, Texture Profile of Malaysian Chicken Balls

The results of the analyses of six brands of commercial chicken balls showed significant differences (p<0.05) in chemical composition, colour and texture among all samples. Most of the samples contained high moisture content (between 60.14-72.81%), with protein content ranging from a low of 9.93% to moderately high of 15.06%. However, the fat content displayed an inverse relationship as compared to protein, ranging from 4.26-14.00%. The low ash content ranging from 1.92-2.82%, could be contributed by the presence of salts and flavoring ingredients in the chicken balls. The difference in carbohydrate content ranging from 5.54-20.85%, indicated high usage of meat substitute in certain brands tested. The L, a and b values of cooked chicken balls ranged between 69.61-77.96, -2.02 to 0.33 and 15.66-19.70 respectively. The hardness, cohesiveness, springiness and shear force ranged between 3.73-5.73, 0.55-0.69, 11.40- 13.71, 31.27-53.77 and 0.51-1.28, respectively. Chewiness readings obtained were between 31.27-53.77, possibly contributed by the different thickeners used in the formulations. The research result shows that Malaysian commercial chicken balls are significantly different in their chemical composition, colour and textural properties.
Effect of H2 and Redox Condition on Biotic and Abiotic MTBE Transformation

Laboratory studies conducted with surface water sediment from a methyl tert‐butyl ether (MTBE)‐contaminated site in South Carolina demonstrated that, under methanogenic conditions, [U‐14C] MTBE was transformed to 14C tert‐butyl alcohol (TBA) with no measurable production of 14CO2. Production of TBA was not attributed to the activity of methanogenic microorganisms, however, because comparable transformation of [U‐14C] MTBE to 14C‐TBA also was observed in heat‐sterilized controls with dissolved H2 concentrations > 5 nM. The results suggest that the transformation of MTBE to TBA may be an abiotic process that is driven by biologically produced H2 under in situ conditions. In contrast, mineralization of [U‐14C] MTBE to 14CO2 was completely inhibited by heat sterilization and only observed in treatments characterized by dissolved H2 concentrations < 2 nM. These results suggest that the pathway of MTBE transformation is influenced by in situ H2 concentrations and that in situ H2 concentrations may be an useful indicator of MTBE transformation pathways in ground water systems.
Click-Chemie: diverse chemische Funktionalität mit einer Handvoll guter Reaktionen

Betrachtet man die in der Natur am haufigsten vorkommenden Verbindungen, so fallt auf, dass die Bildung von Kohlenstoff-Heteroatom-Bindungen gegenuber der von Kohlenstoff-Kohlenstoff-Bindungen deutlich bevorzugt ist. Da zum einen Kohlendioxid die Basisverbindung der Natur ist und andererseits das Medium naturlicher Reaktionen zumeist Wasser ist, uberrascht dies sicherlich nicht. Nucleinsauren, Proteine und Polysaccharide sind polymere Kondensationsprodukte kleiner Untereinheiten, die durch Kohlenstoff-Heteroatom-Bindungen verknupft sind. Sogar die etwa 35 Baueinheiten, aus denen diese essentiellen Verbindungen bestehen, enthalten nicht mehr als sechs aufeinander folgende C-C-Bindungen, sieht man einmal von den drei aromatischen Aminosauren ab. Mit der Natur als Vorbild richteten wir unser Interesse auf die Entwicklung leistungsfahiger, gut funktionierender und selektiver Reaktionen fur die effiziente Synthese neuartiger nutzlicher Verbindungen sowie kombinatorischer Bibliotheken mittels Heteroatomverknupfungen (C-X-C). Diese Synthesestrategie nennen wir „Click-Chemie“. Click-Chemie ist durch eine Auswahl einiger weniger nahezu idealer Reaktionen charakterisiert, mit all ihren Grenzen und Moglichkeiten. In diesem Beitrag werden zum einen die strengen Kriterien, die Reaktionen erfullen mussen, um die Bezeichnung „Click-Chemie“ zu verdienen, definiert, zum anderen werden Beispiele fur molekulare Strukturen gegeben, die mit dieser spartanischen, aber dennoch leistungsfahigen Synthesestrategie leicht hergestellt werden konnen.
Sward canopy structure and the bite dimensions and bite weight of grazing sheep

Seventeen grass or oats swards, displaying a wide and largely independent variation in surface height and bulk density, were produced using different seed rates at sowing and different cutting or grazing pre-treatments. Four sheep confined in cages were allowed to take twenty bites from small patches of each sward, and measurements of bite weight and the physical dimensions of the average bite in the sward (bite depth, area and volume) were related to a range of sward structural characteristics. Mean bite weight per sward ranged from 40 to 330 mg dry matter (DM). It was positively related to surface height (range 6–55 cm), which acted primarily upon bite depth and hence bite volume, and to the bulk density of the grazed stratum (range 0·1–2·0 mg DM cm −3) which influenced bite weight directly. The effects of surface height and grazed stratum bulk density were independent and additive, resulting in a planar response surface. The influence of sward variables on bite area was less clear than on bite depth, but within a given grass species the effect of surface height appeared to be positive and that of the population density of grazed leaves and stems negative. These findings are considered in relation to a theory concerning grazing mechanics. The merits of the grazing cage technique are discussed and suggestions made for further work.