Miracle-dz/UniFAR-FTUs huggingface dataset:
Fermi Level Alignment and Electronic Levels in “Molecular Wire” Self-Assembled Monolayers on Au

One- and two-photon photoelectron spectroscopies were used to determine the electronic structure around the Fermi level for self-assembled monolayers of a prototypical "molecular wire", 4,4'-(ethynylphenyl)-1-benzenethiol(C 6 H 5 -C≡C-C 6 H 4 -C≡C-C6H5-SH), on Au. One-photon ultraviolet photoelectron spectroscopy indicated a separation between the Fermi level and the peak of the occupied delocalized π levels of 1.9 eV, thus providing a representative value for the hole injection barrier. Two states were identified in two-photon photoelectron spectroscopy measurements corresponding to excitation to the lowest exciton and excitation to an unoccupied final state derived from the e 2 u levels of benzene. The separation between the Fermi level and the corresponding unoccupied π* states is estimated to be 3.2 eV, giving a transport gap of ∼1.9 + 3.2 = 5.1 eV. Occupied states associated with Au-S interactions are observed near the Fermi level for comparison studies on benzenethiol monolayers. Charge transfer associated with the formation of these levels, and their unoccupied counterparts, is suggested to produce the approximately 0.7 eV shift of the Fermi level toward the highest occupied orbitals on the oligomer.
Monitoring the Cross-Linking of a HPAm/Cr(III) Acetate Polymer Gel Using 1H NMR, UV Spectrophotometry, Bottle Testing, and Rheology

Abstract The gelation of a polymer gel formulated at 40°C with 7500 mg/L of partly hydrolyzed polyacrylamide (HPAm) and 3000 mg/L of Cr(III) acetate 50% active was monitored for 72 h using 1H nuclear magnetic resonance (NMR) techniques, oscillatory rheology, bottle testing, and UV spectrophotometry. During the first 5 h, 1H NMR techniques detected changes in the polymer gel signal intensity and transverse relaxation that may be related to the rheological properties of the HPAm/Cr(III) acetate polymer gels. Bottle testing and UV spectrophotometry detected additional changes during 30 and 72 h respectively. Monitoring of the gelation process using these techniques is presented here.
Application of In Situ Microfibrillization to Recycling Ultraviolet‐Aged Poly(Ethylene Terephthalate) (PET) and High Density Polyethylene (HDPE)

The potential of in situ microfibrillization for recycling ultraviolet‐aged high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) mixtures was investigated. The photodegradation of HDPE and PET was conducted through accelerated irradiation in an ultraviolet (UV) chamber. The ultraviolet‐aged HDPE and PET was melt blended (in 80/20 wt. ratio) and rectangular slit die extruded, followed by hot stretch and quenching; thus the in situ microfibrillar PET/HDPE blends were fabricated. Gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT‐IR), and contact angle measurements indicate that HDPE and PET suffered photodegradation. There is an increase in yield strength and tensile modulus as well as Vicat softening temperature (VST) tests for in situ microfibrillar blends with increasing UV exposure time, while there is a decrease in these properties for conventional blends, indicating that the in situ microfibrillar blend process has promising potential for recycling plastic mixtures.
Unimolecular decomposition of the neopentyl radical

The kinetics of the unimolecular decomposition of the neopentyl radical has been investigated. Experimentally, the decomposition was monitored in time-resolved experiments by using a heatable tubular reactor coupled to a photoionization mass spectrometer. The radicals were produced indirectly by pulsed excimer laser photolysis of CCl{sub 4} (to produce CCl{sub 3} + Cl) followed by the rapid reaction between the Cl atoms and neopentane to produce neo-C{sub 5}H{sub 11} + HCl. Unimolecular rate constants were determined as a function of bath gas (He, N{sub 2}, and Ar), temperature (10 temperatures between 560 and 650 K), and bath gas density ((3{minus}30) {times} 10{sup 16} molecules cm{sup {minus}3} (He) and (6{minus}12) {times} 10{sup 16} (N{sub 2}, Ar)). The data were fitted within the framework of RRKM theory by using a vibrational model. The high-pressure rate constant in the temperature range studied was determined to be k(neopentyl {yields} isobutene + CH{sub 3}) = 10{sup 13.9 {plus minus} 0.5} exp({minus}30.9 {plus minus} 1.0 kcal mol{sup {minus}1}/RT) s{sup {minus}1}. The average step sizes down for the bath gases used (adjusted parameters in the RRKM calculations) are comparable: 200 (He), 130 (N{sub 2}), and 140 (Ar) cm{sup {minus}1} (all {plus minus} 60 cm{sup {minus}1}). The high-pressure-limit ratemore » constant expression for the reverse reaction, nonterminal addition of CH{sub 3} to isobutene, was obtained from thermochemical calculations by using the results of this study: k(CH{sub 3} + isobutene {yields} neopentyl) = 3.7 {times} 10{sup {minus}13} exp({minus}10.6 kcal mol{sup {minus}1}/RT) cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. The Arrhenius parameters of this addition reaction indicate that nonterminal addition is inhibited relative to terminal addition mostly by a larger energy barrier to addition, as opposed to possible entropic effects. « less
Transport of Organic Compounds in Thermoplastic Geomembranes. I: Mathematical Model

A quasi-two-dimensional partition-diffusion transport model was developed to determine the diffusion coefficient and partition coefficient for various types of geomembranes from measurements of aqueous organic compound concentrations in a confined, double-compartment apparatus with a geomembrane separating the two compartments. The geomembranes tested were high-density polyethylene (HDPE), very low-density polyethylene (VLDPE), and polyvinyl chloride (PVC) and the permeants were mixtures of methylene chloride, toluene, trichloroethylene (TCE), and \im-xylene at 10–100 mg/L. The diffusion coefficient increased exponentially with aqueous concentration and decreased exponentially with geomembrane thickness. The partition coefficient was unaffected by compound concentration and membrane thickness. As HDPE geomembranes were stretched by 5% of their original length, the partition coefficient increased by 0.15–0.6 times. VLDPE had 1.8–3.3 times greater partition coefficients and 1.6–2.8 times greater diffusion coefficients than HDPE, while PVC had 6.2–8.3 times greater partition coefficients and 1–1.8 times greater diffusion coefficients than HDPE.
The use of pine bark as a natural adsorbent for persistent organic pollutants – study of lindane and heptachlor adsorption†

Pine bark obtained as a sawmill by-product in the north of Portugal was used for the adsorption of lindane and heptachlor, two organochlorine pesticides classified as POPs (Persistent Organic Pollutants), from aqueous solutions. It is intended that this natural adsorbent be used as an alternative to activated carbon in an innovative approach for the removal of these classes of compounds, reducing significantly the regeneration costs of the process, thus providing for its intensification. The analytical methodology validated for pesticides' quantification consisted of solid-phase microextraction (SPME) prior to gas chromatography with electron capture detection (GC-ECD), which presented limits of detection for lindane and heptachlor of 0.067 μg/dm 3 and 0.062 μg/dm 3 , respectively. Repeatability, reproducibility and recovery were the parameters tested for validation, yielding better results for lindane. For the bark particle size used (125-300 μm), the average efficiency of removal attained for lindane was 80.6%, and 93.6% for heptachlor with the equilibrium time set at 24h. Both Langmuir and Freundlich models were tested for the adsorption isotherm, but only the second approach produced reliable results for the adsorption parameters. Values obtained for log(K ow ) were 3.17 for lindane (R 2 =0.9927) and 4.85 for heptachlor (R 2 =0.9401).
Anisotropic films of polypyrrole formed electrochemically using a non-planar dopant

We report the electrochemical preparation of electrically conducting films based on polypyrrole, using 10-camphorsulfonate as the dopant, which exhibit a highly anisotropic molecular organisation. This contrasts with earlier reports, in which anisotropy appeared to be restricted to films prepared using aromatic-based planar dopants. Possible growth mechanisms for these materials to account for the molecular anisotropy are discussed.
Experimental Aspects of Mechanistic Studies on Aqueous Ozone Decomposition in Alkaline Solution

Abstract Ozone decomposition in aqueous solution was studied by the stopped - flow method over the pH 10.4 - 13.2 range at 25 ± 0.1 °C and I = 0.5 M NaClO4. At 260 nm the molar absorptivity of aqueous ozone was determined to be 3135 ± 22 M−1cm−1. It was shown that various experimental factors may significantly alter the course of the reaction. Even small amounts of H2O2 absorbed by the plastic parts of the stopped-flow instrumént can affect the kinetic features of the reaction for an extended period of time. Under strictly controlled experimental conditions sufficiently reproducible data could be obtained for the decomposition. The data were evaluated by comparing experimental and simulated kinetic traces. A detailed kinetic model was developed which is able to predict the decay and life-time of ozone as well as the formation and decomposition of the ozonide ion radical (O3 −) over the pH 10.4 - 13.2 range.
Mass spectra of Δ4‐ and 5α‐3‐ketosteroids formed during the oxidation of some 3β‐hydroxysteroids by cholesterol oxidase

Thirty-six delta5- and 5'alpha-3beta-hydroxysteroids have been oxidized with cholesterol oxidase to give the corresponding delta4- and 5alpha-3-ketosteroids, respectively. The mass spectral characteristics of the products (or their trimethylsilyl ether derivatives, in the case of 3-keto-hydroxysteroids) varied considerably, depending especially on the nature of the C-17 sidechain. The ion of m/e 124 (or its equivalent) from cleavage of ring B was frequently a major fragment from delta4-3-ketosteroids, but in some instances was of insignificant abundance. Trimethylsilylation of the product of the oxidation of neoergosterol gave neoergosterone enol-trimethylsilyl ether. Fragmentations of the sidechain predominated in the mass spectra of the 5alpha-3-ketosteroids.
Protocol for Quantitative Detection of Elemental Sulfur and Polysulfide Zero‐Valent Sulfur Distribution in Natural Aquatic Samples

A HPLC‐based protocol has been developed for the determination of zero‐valent sulfur (ZVS) speciation, including solid, colloidal elemental sulfur and individual inorganic polysulfides in natural aquatic samples. The protocol includes four experimental procedures: (1) determination of polysulfide speciation by rapid single‐phase derivatisation with methyl trifluoromethanesulfonate; (2) determination of the sum of polysulfide and colloidal sulfur by reaction with hydrogen cyanide (cyanolysis); (3) determination of total zero‐valent sulfur by treatment with zinc chloride followed by extraction with chloroform; and (4) chromatographic determination of polythionates without sample pre‐treatment. With proper sampling and preservation techniques in the field or on board ship, this combination of methods allowed the quantitative determination of: (a) individual polysulfide species; (b) dispersed colloidal sulfur; (c) dispersed solid elemental sulfur; and (d) tetra‐, penta‐ and hexathionates. With minor modification, the method could be expanded to include other polythionates. Sixteen various wet chemical and liquid chromatographic methods were tested on nine synthetic reference samples (including solid elemental sulfur, colloidal elemental sulfur, inorganic polysulfides and polythionates) to establish the optimal protocol. The protocol was further evaluated by analysing the zero‐valent sulfur content in microbially‐produced sulfur and in sulfur from two natural samples of sulfide‐rich seawater from tidal flats pools of the Wadden Sea (Germany).
Soil amelioration effects on boron uptake by sunflowers

Abstract Results of field trials with sunflowers grown on an Ultisol over three seasons indicated that applications of lime and gypsum had little effect on the boron concentration in plant tissues. Only when 30 kg borax/ha/annum had been applied did soil amelioration slightly but significantly decrease the B concentration in 1‐month‐old sunflower seedlings. Liming for three seasons significantly decreased the B concentration in the topmost mature leaf at flowering only when 30 kg borax/ha/annum had been applied and the pH (N KCl) was 4.4 and above. A pot experiment with the same soil was designed to test whether high pH levels affected B uptake. The reduction of toxic aluminum markedly increased top and root growth but higher rates of line had no further benefit. Liming significantly decreased the B concentration in seedling tope but the total B content of the tops was increased by liming. It appeared that liming to pH (N KCl) 7.0 did not adversely affect the uptake and translocation of B by sunflower roo.
A simple model framework for the prediction of controlled release from bulk eroding polymer matrices

A broadly applicable model for predicting controlled release could eliminate the need for exploratory, in vitro experiments during the design of new biodegradable matrix-based therapeutics. We have developed a simple mathematical model that can predict the release of many different types of agents from bulk eroding polymer matrices without regression. New methods for deterministically calculating the magnitude of the initial burst and the duration of the lag phase (time before Fickian release) were developed to enable the model's broad applicability. To complete the model's development, such that predictions can be made from easily measured or commonly known parameters, two correlations were developed by fitting the fundamental equations to published controlled release data. To test the model, predictions were made for several different biodegradable matrix systems. In addition, varying the readily attainable parameters over rational bounds shows that the model predicts a wide range of therapeutically relevant release behaviors.
The Chemical and Biological Properties of Protopine and Allocryptopine

The isoquinoline alkaloids, protopine and allocryptopine are components of numerous phytopreparations. The wide spectrum of biological activities reported for these alkaloids include multiple actions on the cardiovascular system, anti-thrombotic, anti-inflammatory, anti-spasmodic, neuroprotective, anti-bacterial, anti-viral, anti-fungal and anti-parasitic activities. This review aims to summarize recent knowledge on the basic chemistry, analysis, above biological activities, and application of both alkaloids published within the period 1995-2010.
A Raman spectroscopic investigation of graphite oxide derived graphene

Graphene sheets that are now routinely obtained by the exfoliation/reduction of graphite oxide exhibit Raman spectra unlike traditional graphene systems. The general attributes of the Raman spectra of these ‘wrinkled graphene’ are first reaffirmed by evaluating the spectra of samples prepared by seven different exfoliation-reduction methods. These graphene sheets exhibit highly broadened D and G Raman bands and in addition, have a modulated bump in place of the conventional 2D (G′) band. It is shown that the high wavenumber ‘bump’ can be resolved into the conventional 2D band and several defect activated peaks such as G*, D+D′ and 2D′. The broad G band could also be deconvoluted into the actual G band and the D′ band, thereby attributing the broadening in the G band to the presence of this defect activated band. Two additional modes, named as D* at 1190 cm-1 and D** at ∼1500 cm-1 could be identified. These peculiar features in the Raman spectrum of ‘graphene’ are attributed to the highly disordered and wr.
X‐ray diffraction refinement of the crystal structure of anosovite prepared from leucoxene

The crystal structure of anosovite, (Ti1.69Al0.26Fe0.05)3+(Ti0.97Zr0.03)4+O5, prepared by carbothermal reduction of leucoxene under vacuum at 1450°C has been refined by Rietveld method using powder X‐ray diffraction data. It was found that it represents slightly monoclinically deformed pseudobrookite type structure with lattice parameters a = 9.8111 Å, b = 3.7509 Å, c = 9.9468 Å, β = 90.628°. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positive and Negative Artifacts in Particulate Organic Carbon Measurements with Denuded and Undenuded Sampler Configurations Special Issue of Aerosol Science and Technology on Findings from the Fine Particulate Matter Supersites Program

Measurement of ambient particulate organic carbon (POC) with quartz filters is prone to positive and negative sampling artifacts. One approach for estimating these artifacts is to sample with a backup quartz filter placed behind either the main quartz filter or a Teflon filter in a parallel line. Another approach is to use a denuder to reduce the positive artifact in combination with a highly adsorbent backup filter to capture any negative artifact. Results obtained using both of these approaches in parallel for over one year in Pittsburgh, PA are presented in this article. A sampler using an activated carbon monolith denuder has been developed and tested extensively. Transmission losses were found to be negligible, and the denuder is on average 94% efficient at removing gas-phase organics. Denuder breakthrough is corrected for each run using a dynamic blank in parallel with the sample line. Comparisons with the dynamic blank indicate that the denuder almost eliminates the positive artifact on the quartz filter. Negative artifact from the denuded quartz filter is quantified using a carbon-impregnated glass fiber (CIG) backup filter and was found to be small, typically less than 10% of the ambient POC. Compared to the denuded sampler POC, 24 h bare quartz samples showed an almost constant positive artifact of 0.5 μg-C/m3 for samples taken throughout the year-long study period. Sampling for shorter durations (4–6 h) resulted in a larger positive artifact. A quartz filter behind a Teflon filter (QBT) provides a consistent estimate of the positive artifact on the bare quartz filter irrespective of sample duration, though it overcorrects for the positive artifact by 16–20% (attributed to particulate matter volatilizing off the upstream Teflon filter). The quartz behind quartz (QBQ) approach provides a reasonable estimate of the positive artifact on the bare quartz filter for the 24 h samples but not for the shorter samples. A slight seasonal variation is observed in the absolute value of the positive artifact, with higher values observed during the summer months.
Investigating the Chemical Characteristics of Soil Organic Matter Fractions Suitable for Modeling

Current models of soil organic matter (SOM) turnover tend to invoke pools that are defined by their contrasting first-order reactivity constants but which cannot be directly measured. New models may be based around fractions defined by procedures that can be used to isolate them experimentally. The drawback of such fractions is that they may display properties that are not sufficiently distinct or which vary in time or space. In this study the properties of two fractions from soils of contrasting geographical origin and under different nutrient management were examined using 13 C nuclear magnetic resonance (NMR) spectroscopy. The fractions were free SOM (FR-SOM, discrete organic particles located between stable aggregates), and intra-aggregate SOM (IA-SOM, discrete organic particles within stable aggregates). The composition of both fractions was highly consistent across soil types and environments, but the fractions differed significantly in the proportion of C present in five of the seven functional C groups identified by NMR (P <-0.05). The results confirmed that IA-SOM contains a greater proportion of microbial products and more resistant C as compared with the FR-SOM. Nutrient management affected fraction composition in four functional groups most abundant in plant material or farmyard manure (P < 0.05). The effects were considerably less pronounced when the analysis was restricted to plots receiving inorganic (or zero) N. Overall the results supported the view that free and intra-aggregate organic matter occupy contrasting positions in the decomposition sequence, and are likely to display reactivities sufficiently distinct to operate as discrete pools in new SOM models.
Rapid and simultaneous analysis of free sterols, tocopherols, and squalene in edible oils by coupled reversed-phase liquid chromatography-gas chromatography

On-line coupling of reversed-phase liquid chromatography and gas capillary chromatography (RPLC-GC) using a programmed temperature vaporizer (PTV) as interface is used for the direct and simultaneous analysis of free sterols, tocopherols, and squalene of edible oils by direct injection (that is, without the need for prior enrichment of the sample). The proposed method allows large volume fractions of water methanol eluents to be transferred into the GC system, 2000 μL/min being the speed of sample introduction. The overall procedure including LC preseparation, transfer from LC to GC, and GC analysis takes <1 h. Keywords: On-line coupled RPLC-GC; sterols; tocopherols; squalene; direct analysis; edible oils
Studies on egg shells. II.—A method for marking and counting pores†

A method has been developed for marking the pores in egg shells by immersing them in concentrated nitric acid for very short periods of time. This makes the pores easily visible under the microscope, and counting can then be done by a statistical method. Not only is the total number of pores determined, but also a frequency distribution is obtained which indicates that the pores are not distributed at random.
Investigation of the fate of poplar lignin during autohydrolysis pretreatment to understand the biomass recalcitrance

Lignocellulosic biomass is the most abundant renewable resource for the potential replacement of fossil fuels, though to fully realize this vision, an improved understanding of the chemical structures of its components within the biomass and after bioprocessing is critical. In this study, we investigated the fate of isolated poplar lignin during autohydrolysis pretreatment at different temperatures and subsequently analyzed the structural changes by gel permeation chromatography, 13C–1H HSQC and phosphorylation/31P NMR. Our results suggested that an increase in temperature and time of autohydrolysis of lignin resulted in an increase in phenolic hydroxyl groups coupled with a decrease in aliphatic hydroxyl groups. This may be attributed to the cleavage of β-O-4 linkages via acidolysis. Molecular weight determination revealed that lignin depolymerization predominates over condensation. Our results also highlight that the cleavage of lignin side-chain units is relatively fast in lignin autohydrolysis compared to the autohydrolysis of biomass. This study provides an enhanced understanding of the fundamental autohydrolysis pretreatment lignin chemistry and will facilitate improved methodology to reduce biomass recalcitrance.