MOLECULAR-DYNAMIC SIMULATION OF MIXTURES OF MODIFIED FULLERENES AND 1,8-OCTANDITHIOL

В данной работе мы сообщаем о результатах сравнительного атомистического моделирования двух систем, содержащих функцианализированные фуллерены метилового эфира фенил- C-масляной кислоты (PCBM ) и фенил- C-масляной кислоты (PCBM ) в присутствии растворителя 1,8-октандитиола (ODT). Для реализации расчетов использовался метод молекулярной динамики на базе программного пакета LAMMPS. Зафиксировано принципиальное различие в упаковке молекул PCBM и PCBM . В случае систем с PCBM наблюдается тенденция к постепенному разделению растворителя и фуллеренов. При этом в образцах с PCBM наблюдается тенденция к формированию устойчивых трехмерных сетчатых структур, образованных двумя взаимопроникающими фазами: фуллеренами и молекулами ODT. С целью проверки масштабируемости наблюдаемого структурного упорядочения для смеси PCBM с ODT было выполнено моделирование в ячейке с удвоенным размером ребер. В этом случае мы также наблюдаем формирование биконтинуальных структур из фуллеренов и растворителя. In this work, we report on the results of comparative atomistic modeling of two systems containing functionalized fullerenes of phenyl-C-butyric acid methyl ester (PCBM ) and phenyl- C -butyric acid (PCBM ) in the presence of a high-boiling solvent 1,8 -octanedithiol (ODT). The calculations were performed by full atomistic molecular dynamics with using LAMMPS software package. A fundamental difference in the packaging of PCBM and PCBM molecules was detected. In the case of systems with PCBM , there is a tendency towards gradual separation of the solvent and fullerenes. At the same time, in samples with PCBM , there is a tendency to the formation of stable three-dimensional network structures formed by two interpenetrating phases: fullerenes and ODT molecules. In order to check the scalability of the observed structural ordering for the mixture of PCBM with ODT, an additional simulation was performed in a cell with doubled edge size. In this case, we also observe the formation of bicontinual structures from fullerenes and the solvent.

Evaluation of Solvents Used as Keepers in the Determination of Organic Pollutants by GC/MS

Solvent evaporation is often used in the sample preparation procedure for the determination of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organic pesticides. Because of the loss of analyte during this step, a high-boiling solvent, i.e., a keeper, is often added to the extract before evaporation. However, there are almost no basic studies found in the literature on the selection of keepers for the appropriate type of analytes (keepers are usually selected only on the basis of information provided by various recommendations). In this work, the effect of several keepers (isooctane, toluene, nonane, octanol, dodecane) on the recovery of various analytes (PAHs, PCBs, organic pesticides) was evaluated (during evaporation in a stream of nitrogen, at 40 °C). The analysis of the results obtained for the tested compounds shows that 1-octanol is a universal keeper for compounds with low volatility, i.e., PCBs (average recovery: 97.6%), organochlorine pesticides (average recovery: 95.0%), organophosphorus pesticides (OPPs; average recovery: 99.7%) and higher mass PAHs (average recovery: 91.9%). The use of isooctane as a keeper yields high recoveries for PAHs, regardless of their volatility (average recovery: 95.5%). When using 1-octanol or dodecane as a keeper, the reversed solvent effect (during GC analysis) was noted in relation to volatile analytes causing the distortion of their peaks. Additionally, the phenomenon of loss of some analytes (e.g., OPPs) was observed during evaporation without heating the vials. However, in the case of PCBs, organochlorine pesticides (OCPs) and o-hydroxybiphenyl, evaporation under such conditions yields recoveries greater than or equal to 90.0%. The results presented in this work can help in finding a suitable keeper for a specific group of analytes or an alternative to the commonly used one, especially in the case of recovery problems.

Rapid Estimating Rumen Digestibility of Forage with Lignin Structures Based on Fourier-Transform Infrared Spectroscopy

The experiment was aimed to predict the relationship between rumen degradation parameters and chemical composition, especially acid detergent lignin, and molecular structure profiles of lignin (the relative content ratio of syringyl and guaiacyl unit) of twenty-two herbaceous and leguminous forage, which were commonly used as roughage for dairy cows in the northeast of China. Analyses of the spectra of forage materials' high boiling solvent lignin samples showed that common features and specific vibrations to each unique lignin were found in the spectrum. In this paper, the spectra of materials high boiling solvent lignin demonstrated absorption at the band around 1332 cm–1 (syringyl) and 1258 cm–1 (guaiacyl). The spectra indicated that the lignin of the plant materials used in this study are H-G-S type. A broad range was found among the chemical composition for each feedstuff. The degradation kinetics characteristics among feedstuffs also had relatively large range of variation. The relative content ratio of syringyl (S) and guaiacyl (G) unit of leguminous samples positively correlated with some rumen degradation characteristics. However, there was no correlation between relative content ratio of S and G unit and degradation parameters among the herbaceous materials (p > 0.05). According to analyses, content acid detergent lignin (ADL) and relative content ratio of S and G could be the predictors of the degradation parameters expect SCP among forage. In conclusion, the relative content ratio of S and G might be potentially used to predict some of the degradation parameters (Kd CP, EDCP, SNDF) of leguminous feedstuffs.

Synthesis and high-resolution structural and chemical analysis of iron-manganese-oxide core-shell nanocubes

We have investigated the structure and chemical composition of nanoparticles synthesized by thermal decomposition of a mixture of iron oleate and manganese oleate in a high-boiling solvent in the presence of Na-oleate and oleic acid as surfactants by analytical transmission electron microscopy (TEM). The particles appear core-shell like in bright field TEM images. Higher spatial resolution TEM (HRTEM) analysis reveals a FeO/MnO like structure in the core and a spinel like structure in the shell. With high-resolution analytical methods like energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS), the distribution of the metals Mn and Fe was investigated. Differences in the oxidation state of these metals were found between the core and the shell region. The presence of sodium from the used surfactant (Na-oleate) on the surface of the particles has been proved.

Synthesis and optical properties of AgInS2 nanoparticles

Ternary chalcogenide Ag-In quantum dots (QDs) are more environmentally friendly than known Cd-, Pb- and P-containing nanoparticles. Here we review the literature on colloidal synthesis methods, properties, and promising fields for the application of AgInS2 quantum dots. Similar to the QDs of lead and cadmium chalcogenides, the most accurate control over the structure and morphology of AgInS2 QDs is achieved by using the method of introducing precursors into high-boiling organic solvents. However, to realize the potential applications of ternary quantum dots, in particular as luminescent biomarkers, the quantum dots must be soluble in polar solvents, especially water. The transfer of quantum dots into aqueous solutions is usually accomplished by exchanging primary lyophilic ligands with smaller bifunctional molecules, such as thioglycolic (or mercapto­propionic) acids, which can passivate the surface of the quantum dots while making them soluble in the polar environment. Methods of colloidal synthesis of AgInS2 / ZnS quantum dots can be classified into the following types: Injection of ions into a high-boiling solvent Synthesis in a mixture of solvents Synthesis in the aquatic environment Methods for the synthesis of AgInS2 QDs in both aqueous solution and organic solvent medium are described. Examples of application of quantum dots for biomedical purposes and in photovoltaic and sensory devices are given. Quantum dots have high photostability and brightness, are characterized by a wide range of absorption and narrow spectral bands of radiation, ie meet most of the criteria for fluorescent materials and biosensors for imaging cancer cells in antitumor therapy, immunofluorescent labeling of proteins, detection of toxins s, visualize intracellular structures, etc. Quantum dots of tertiary chalcogenides, in particular CuInS2 and AgInS2, may be an alternative to quantum dots of binary lead and cadmium chalcogenides for use in light-emitting and light-absorbing systems, such as LEDs, sensors and solar absorbers.

Does 1,8-diiodooctane affect the aggregation state of PC 71 BM in solution?

1,8-Diiodooctane (DIO) is an additive used in the processing of organic photovoltaics and has previously been reported, on the basis of small-angle X-ray scattering (SAXS) measurements, to deflocculate nano-aggregates of [6,6]-phenyl-C71-butyric acid methyl ester (PC 71 BM) in chlorobenzene. We have critically re-examined this finding in a series of scattering measurements using both X-rays and neutrons. With SAXS, we find that the form of the background solvent scattering is influenced by the presence of DIO, that there is substantial attenuation of the X-rays by the background solvent and that there appears to be beam-induced aggregation. All three factors call into question the suitability of SAXS for measurements on these samples. By contrast, small-angle neutron scattering (SANS) measurements, performed at concentrations of 15 mg ml −1 up to and including 40 mg ml −1 , show no difference in the aggregation state for PC 71 BM in chlorobenzene with and without 3% DIO; we find PC 71 BM to be molecularly dissolved in all solvent cases. In situ film thinning measurements of spin-coated PC 71 BM solution with the DIO additive dry much slower. Optical imaging shows that the fullerene films possess enhanced molecular mobility in the presence of DIO and it is this which, we conclude, improves the nanomorphology and consequently solar cell performance. We propose that any compatible high boiling solvent would be expected to show the same behaviour.

Synthesis of Small Ce3+-Er3+-Yb3+ Tri-Doped BaLuF5 Active-Core-Active-Shell-Active-Shell Nanoparticles with Strong Down Conversion Luminescence at 1.5 μm

Small fluoride nanoparticles (NPs) with strong down-conversion (DC) luminescence at 1.5 μm are quite desirable for optical fiber communication systems. Nevertheless, a problem exists regarding how to synthesize small fluoride NPs with strong DC emission at 1.5 μm. Herein, we propose an approach to improve 1.5 μm emission of BaLuF5:Yb3+,Er3+ NPs by way of combining doping Ce3+ ions and coating multiple BaLuF5: Yb3+ active-shells. We prepared the BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs through a high-boiling solvent method. The effect of Ce3+ concentration on the DC luminescence was systematically investigated in the BaLuF5:Yb3+,Er3+ NPs. Under a 980 nm laser excitation, the intensities of 1.53 μm emission of BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs was enhanced by 2.6 times comparing to that of BaLuF5:18%Yb3+,2%Er3+ NPs since the energy transfer between Er3+ and Ce3+ ions: Er3+:4I11/2 (Er3+) + 2F5/2 (Ce3+) → 4I13/2 (Er3+) + 2F7/2 (Ce3+). Then, we synthesized BaLuF5:18%Yb3+,2%Er3+,2%Ce3+@BaLuF5:5%Yb3+@BaLuF5:5%Yb3+ core-active-shell-active-shell NPs via a layer-by-layer strategy. After coating two BaLuF5:Yb3+ active-shell around BaLuF5:Yb3+,Er3+,Ce3+ NPs, the intensities of the 1.53 μm emission was enhanced by 44 times compared to that of BaLuF5:Yb3+,Er3+ core NPs, since the active-shells could be used to not only suppress surface quenching but also to transfer the pump light to the core region efficiently through Yb3+ ions inside the active-shells.

Polyurethane-tetraaniline conducting composites: synthesis and their anti-corrosion performance

Purpose – The purpose of this paper is to get the insulating polyurethane (PU) as conductive type polymer by compositing with oligoanilines, namely, tetraaniline (TANi) with an implication of its use as anti-corrosion coating material. Design/methodology/approach – Water dispersion of PU was prepared and used as a host material for TANi for composite formulation. Findings – The composites are very useful as anti-corrosion coating on mild steel as evident from Tafel polarisation studies. Research limitations/implications – The solubility of TANi is limited in other organic solvents; because of this, a high-boiling solvent like N-methyl-2-pyrrolidone (NMP) is used. Practical implications – It can be used as a good anti-corrosion coating on mild steel. Apart from anti-corrosion material, this can be used as conductive-based sensor material and also electrostatic dissipation (ESD) or electromagnetic interference (EMI) shield. Originality/value – The work is original.

Preparation and characterization of high boiling solvent lignin-based polyurethane film with lignin as the only hydroxyl group provider

High boiling solvent (HBS) lignin-based polyurethane film was successfully fabricated with lignin as the only hydroxyl group provider.