Limitations of the Quantification of Organic Carbon in Sediment from C–H Stretching Vibrations in DRIFT Spectra

Abstract

The limitations of quantifying organic carbon (OC) or various organic substances in sediment from the integration of infrared C–H stretching bands using diffuse reflectance infrared Fourier transform (DRIFT) spectra are pointed out, both from theoretical arguments and by presenting experimental data. Such determinations are inaccurate and imprecise because (i) the band at 2930 cm^?1 is not exclusively due to CH₂ groups; (ii) there is a spectral interference from CO₃ ^2? absorption; and (iii) the proportion of CH₂ groups in organic matter varies for different sediments. The measurement of aliphatic C–H stretching band areas only provides an approximate measurement of aliphatic carbon bonded to hydrogen, which turns out to be a factor of about 3 to 3.5 times smaller than the OC content for Hong Kong marine sediments, depending on their nature and origin.     

Investigation of the Chemical Differences between Native and Bypass Coronary Artery Plaques from the Same Heart Using Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance (CP/MAS-NMR)

The plaque deposits in bypass arteries and native arteries from the same heart have been studied using solid state cross polarization nuclear magnetic resonance (CP/MAS NMR). Both ¹³C and ³¹P signals were observed. The samples are of interest because plaque in native arteries may have deposited during the lifetime of the patient. However, plaque in the bypass occurred since bypass surgery. It has been observed that the mature plaque in native arteries was more calcified than that in bypass arteries, especially if the latter had not matured to become significant in size. Results showed that the concentrations of carboxylate carbons present in cholesterol esters were similar in native and bypass arteries. However, the areas of the ¹³C peaks of the carboxylate compared to the sum of areas of all other ¹³C arteries indicated that the carboxylate was attached to five or six other carbons. From this we can calculate that the carboxylate to other carbon ratio in the remainder must be 1:4 or 1:3. This indicates large quantities of other organic compounds in the deposits. Studies of ³¹P showed that phosphorus existed primarily as hydroxyapatite in the crystalline native plaque. However, a large proportion existed as organic phosphorus in the bypass plaque. In addition, we studied the interactions of calcium with homocysteine and cholesterol. Calcium-homocysteine and cholesterol-homocysteine precipitates were characterized using ¹³C solid state NMR. Results showed that calcium appeared to interact with sulphur in the homocysteine which seemed to form dimers and polymers.     

Spatial variations in larch needle and soil δ15N at a forest–grassland boundary in northern Mongolia

The spatial patterns of plant and soil δ¹⁵N and associated processes in the N cycle were investigated at a forest–grassland boundary in northern Mongolia. Needles of Larix sibirica Ledeb. and soils collected from two study areas were analysed to calculate the differences in δ¹⁵N between needle and soil (Δδ¹⁵N). Δδ¹⁵N showed a clear variation, ranging from ?8?‰ in the forest to ?2?‰ in the grassland boundary, and corresponded to the accumulation of organic layer. In the forest, the separation of available N produced in the soil with ¹⁵N-depleted N uptake by larch and ¹⁵N-enriched N immobilization by microorganisms was proposed to cause large Δδ¹⁵N, whereas in the grassland boundary, small Δδ¹⁵N was explained by the transport of the most available N into larch. The divergence of available N between larch and microorganisms in the soil, and the accumulation of diverged N in the organic layer control the variation in Δδ¹⁵N.     

Co3O4 Hollow Polyhedrons as Bifunctional Electrocatalysts for Reduction and Evolution Reactions of Oxygen

It is very important to exploit low‐cost and efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts for the development of renewable‐energy conversion and storage techniques. Although much attention has been made to develop efficient catalysts for ORR and OER, it is still highly desired to create new bifunctional catalysts. In this study, Co₃O₄ hollow polyhedrons are synthesized as efficient bifunctional electrocatalysts for ORR and OER by simple one‐step annealing Co‐centered metal–organic frameworks (ZIF‐67). Due to the large specific surface areas and high porosity, the as‐prepared Co₃O₄ hollow polyhedrons exhibit excellent electrocatalytic activities for ORR and OER in alkaline media. Co₃O₄ hollow polyhedrons show higher peak current density (0.61 mA cm^?2) with four‐electron pathway than Co₃O₄ particles (0.39 mA cm^?2), better methanol tolerance and superior durability (82.6%) than commercial Pt/C electrocatalyst (58.6%) for ORR after 25 000 s. In addition, Co₃O₄ hollow polyhedrons also display excellent OER performances with smaller overpotential (536 mV) for 10 mA cm^?2 than Co₃O₄ particles (593 mV) and superior stability (86.5%) after 25 000 s. This facile one‐step strategy based on metal–organic frameworks self‐sacrificed templates can be used to develop the promising well‐defined porous hollow metal oxides electrode materials for energy conversion and storage technologies.     

Phosphate and amide III mapping in sialoliths with Raman microspectroscopy

Sialoliths, a cause of the salivary gland infection, are reported to be composed of inorganic and organic substances. However, the precise mechanism of sialolith formation remains unclear. The purpose of this report is to elucidate this mechanism by analyzing the precise distribution of phosphate (an inorganic substance) and amide III (an organic substance) in sialoliths by using Raman microspectroscopy. Sialoliths from the submandibular gland duct were analyzed by this form of observation and by a scanning electron microscope (SEM) equipped with an energy‐dispersive X‐ray spectroscope (EDX). In Raman microspectroscopy we analyzed the spectral peak of the phosphate (PO₄³⁻) symmetric stretching vibrational mode (υ₁) at 960 cm⁻¹ and that of amide III at 1265 cm⁻¹ to demonstrate the mapping of an image of these elements showing a semiquantitative distribution of phosphate and amide III in the sialoliths. It was found that phosphate and amide III were concentrated at the center of the sialoliths, and the phosphate distribution in the sialoliths showed concentric laminations. These results indicated the possibility that the sialoliths originated from a nidus of organic materials and progressively grew by the deposition of layers of organic and inorganic materials. Copyright © 2008 John Wiley & Sons, Ltd.     

Isotopic and multielemental fingerprinting of organically and conventionally grown potatoes

Two marker combinations were used for the differentiation of organically produced from conventionally produced potatoes and also for the geographical origin identification. Fifty-seven samples (from Romanian local producers or imported) were analysed from the stable isotopic (isotope ratio mass spectrometry) and elemental profile (inductively coupled plasma mass spectrometry) point of view. In order to assess the best marker combination, both isotopic and elemental experimental results were subject to chemometric analysis. The statistical tests performed were ANOVA test, Pearson correlation, principal component analysis and linear discriminant analysis (LDA). For a more comprehensive differentiation between organic vs. conventional potato samples, LDA was applied, and 94.7?% of original cases were correctly classified and the percentage obtained in cross-validation procedure was 91.2?%. Regarding the geographic origin classification, LDA provided an initial classification of 96.5?%, while for cross-validation the percentage was 87.7. LDA found δ¹⁵N, Cd, Ca, Cu and Zn as best discrimination markers between organically and conventionally grown potatoes. The strongest predictors for Romania vs. foreign geographical areas along LDA were seen to be Ca, P, Co, Ni and δ¹³C.     

Synthesis,Spectral, Solvent Dependent Linear and Nonlinear Optical Characteristics of (E)-N-(3-(3-(4(dimethylamino)phenyl)acryloyl) phenyl)quinolone-2-carboxamide

This paper presents the synthesis of novel organic compound (E)-N-(3-(3-(4(dimethylamino)phenyl)acryloyl)phenyl)quinolone-2-carboxamide, also known as Quinolinecarboxamide Chalcone (QCC) using aldol condensation and carboxamide formation method. The organic sample QCC was examined by FT-IR, ¹H NMR, ¹³C NMR and mass spectroscopic techniques, respectively. Linear and third-order nonlinear optical (TNLO) properties of QCC dissolved in polar solvents such as DMSO, DMF and Ethanol have also been studied. The order of nonlinear refractive index and nonlinear absorption coefficient of QCC was measured to be 10^?11 m²/W and 10^?5 m/W. The nonlinear refractive index (n₂) of QCC was attributed to negative nonlinearity due to self-defocusing effect, and nonlinear absorption coefficient (β) indicates the behaviors of saturable absorption (SA) and reverse saturable absorption (RSA). The real and imaginary features of the TNLO susceptibility (χ⁽³⁾) of QCC in polar solvents were calculated to be the order of 10^─7 esu. The spectral characteristics of solvent on TNLO susceptibility of QCC were discussed. The results divulged that the synthesized organic compound is a novel nonlinear optical (NLO) material for applications in photonics and optoelectronics.

     

Radiological and hyperfine characterization of soils from the Northeastern region of the Province of Buenos Aires, Argentina

The activity concentrations of both natural (²³⁸U and ²³²Th chains and ⁴⁰K) and anthropogenic (¹³⁷Cs) radionuclides down along the soil profile have been determined in soil samples collected from inland and coastal areas of the La Plata River, located in the Northeastern region of the Province of Buenos Aires, Argentina. These studies were complemented with ⁵⁷Fe Mössbauer spectroscopy characterization, pH, texture and organic carbon content measurements. From Mössbauer results, the sample compositions differ from one area to the other. Spectra from both soil samples are dominated by the Fe^3+? paramagnetic signal. For soil samples from the coastal area, the ??-Fe₂O₃ contribution is lower, Fe₃O₄ was not detected, and the relative areas of each spectral contribution are nearly constant with depth. For samples from the inland area, the Fe^3+? paramagnetic fraction increases up to 82%, mainly at the expense of the magnetically ordered phase. The main observed activity originates from the decay of ⁴⁰K (540?C750 Bq/kg), followed by ²³⁸U (60?C92 Bq/kg) and ²³²Th (37?C46 Bq/kg) chains. The activity of ²³⁵U was in all the cases lower than the detection limit (L_D?=?0.02 Bq/kg). The only determined anthropogenic nuclide was ¹³⁷Cs, arising from the fallout of the Southern Hemisphere nuclear weapon tests. Three of the observed differences in the depth distributions can be described by the dispersion-convection model. A correlation between the natural nuclide activities and the Mössbauer relative fractions was found, whereas no correlation was found between the ¹³⁷Cs profile and the relative fraction of Fe₃O₄ or with other iron species.     

Highly Dispersed ZnSe Nanoparticles Embedded in N‐Doped Porous Carbon Matrix as an Anode for Potassium Ion Batteries

Advanced nanostructured functional materials obtained from the precursors of metal–organic frameworks show several unique advantages, including plentiful porous structures and large specific surface areas. Based on this, designed and constructed are highly dispersed ZnSe nanoparticles anchored in a N‐doped porous carbon rhombic dodecahedron (ZnSe@NDPC) by a sequential high‐temperature pyrolysis and selenization method. The specific synthesis process involves a two‐step heat treatment of the template‐engaged reaction between zinc‐based zeolitic imidazolate framework (ZIF‐8) and selenium power. By optimizing the calcination temperature, the as‐synthesized ZnSe@NDPC‐700 as an advanced anode of potassium ion batteries demonstrates the best electrochemical performance, including a high capacity (262.8 mA h g^?1 over 200 cycles at 100 mA g^?1) and a good rate capability (109.4 mA h g^?1 at 2000 mA g^?1 and 52.8 mA h g^?1 at 5000 mA g^?1). Moreover, the capacitance and diffusion mechanisms are also investigated by the qualitative and quantitate analysis, finally accounting for the superior K storage.     

一种新型有机染料的宽带双光子吸收和光限幅特性的研究

研究了一种新型双共轭链有机染料分子的双光子吸收（TPA）及其光功率限幅特性，实验研究了该有机染料的双光子吸收谱和光功率限幅曲线. 结果证实在浓度为1×10^-2 mol/L的四氢呋喃（THF）溶液中，该有机染料在近红外区有宽达400nm的宽带非线性双光子吸收及光功率限幅特性. 它的双光子吸收谱存在三个峰，分别位于730，850和980nm，并且在850nm处有最大的TPA截面，为σ′₂＝25.9×10^-47　cm^{4·s 关键词： 宽带 双光子吸收 光限幅 双共轭链有机分子}     

Comparative charge transfer studies in nonmetallated and metallated porphyrin fullerene dyads

Single material organic solar cells become an interesting area of research to overcome the challenges with efficient charge separation efficiencies in conventional organic solar cells. In this article, we have synthesized nonmetallated and metallated porphyrin‐fullerene dyad materials (H2P‐C60 and ZnP‐C60, respectively) with simple structure, comprehensively studied their charge transfer mechanism, and established a proof of concept that nonmetallated porphyrin‐fullerene dyads are better candidates to be used in organic solar cells compared with metallated dyads. Absorption and electrochemical analysis revealed the ground state electronic interactions between donor‐acceptor moieties in both types of dyads. Driving force (?ΔG^o_ET) for intramolecular electron transfer process was calculated by first oxidation and reduction potentials of dyads. The excited state electronic interactions were characterized by time‐resolved fluorescence and pump‐probe transient absorption experiments. Strong fluorescence quenching of porphyrin along with reduced lifetimes in dyads due to deactivation of singlet excited states by photoinduced charge transfer process between porphyrin/Zn‐porphyrin core and fullerene in different polarity solvents was observed. Transient absorption spectroscopy was also applied to identify the transient spectral features, ie, cationic (H2P⁺/ZnP⁺) and anionic (C₆₀^?) radicals formed because of the charge separation in both types of dyads. Finally, organic solar cell device was also fabricated using the dyads. We obtained higher V_oc, J_sc, and fill factor in single material organic solar cell using H2P‐C60 compared to previous reports.     

Photoelectron spectroscopy of irontricarbonyl complexes of vinylnaphthalenes: Quantum-chemical calculations by the density functional method

The HeI photoelectron spectra of the complexes η⁴-1-vinylnaphthalene-Fe(CO)₃ and η ⁴-2-vinylnaphthalene-Fe(CO)₃ and the free organic ligands 1-vinylnaphthalene and 2-vinylnaphthalene are measured. The spectra are interpreted on the basis of quantum-chemical calculations by the density functional method in the SVWN/6-31G(d) local density approximation and with the B3LYP/6-31G(d) hybrid exchange-correlation functional. The Kohn-Sham orbital energies with calibration corrections are shown to reproduce well the vertical ionization potentials of both the irontricarbonyl π complexes under study and their ligands. The relative ionization cross sections σ_i of the valence orbitals of the complexes are calculated in terms of the Gelius model. These quantities prove to agree perfectly with the relative ionization cross sections σ _i ^exp determined experimentally from direct estimation of the band areas of the photoelectron spectra.     

Organic insulator layer influence on the electrical properties of N,N’-di (2-ethylhexyl) - 3, 4, 9, 10-perylene diimide organic thin-film transistors: Experiment and modeling

In this work, n- type organic thin film transistors (OTFTs) based on different kinds of organic dielectrics were fabricated, characterized and theoretically investigated. Three kinds of organic insulators were applied as dielectric gate which are: divinyl tetramethyl disiloxane-bis (benzo-cyclobutene) (BCB), poly(vinylalcohol) (PVA) and poly (4-vinyl phenol) (PVP). Analytical model was applied to describe the electrical behavior of the fabricated OTFTs and to explain the absence of saturation of the drain current for the device based on PVA dielectric. In addition, Meyer–Neldel rule-grain boundary model was applied for the calculation of total resistance of OTFTs based on different dielectrics materials. The theoretical results of output characteristics and total resistance showed an excellent agreement with the experimental measurements. The experimental and theoretical calculations revealed that the n-channel OTFTs based on BCB as an insulator layer exhibited superior electrical characteristics in terms of threshold voltage, mobility and drain current compared with the devices based on PVA and PVP as a gate insulator layer. The device based on BCB organic insulator layer has the largest mobility of 4?×?10^?3 cm² V^?1 s^?1, the smallest leakage current relative to the devices based on PVA and PVP. While, the device fabricated with PVP organic insulator gate has a large trap density on the PVP-EHPDI interface which causes a pronounced decrease in field effect mobility and consequently drain current.     

利用空间电荷限制电流方法确定三(8-羟基喹啉)铝的电子迁移率特性初步研究

材料的迁移率是其关键电学特性之一.有机材料迁移率的研究对于有机电致发光器件、 有机太阳电池、有机薄膜场效应晶体管性能的提高有重要的意义. 应用简单易行的空间电荷限制电流方法,对基于三(8-羟基喹啉)铝(Alq₃) 的四种单载流子器件电流密度-电压曲线特性进行研究, 根据空间电荷限制电流模型,拟合出Alq₃材料在四种器件中的零场电子迁移率和电场依赖因子,并且给出Alq₃电子迁移率随外加偏压的变化趋势. 实验结果表明,顶电极铝蒸镀到缓冲层氟化锂(1 nm)和Alq₃ (100 nm)的表面后, 可以明显改善Alq₃的零场迁移率和电场依赖因子. 认为产生这种现象的原因是氟化锂可以使铝和Alq₃发生络合反应, 形成Li⁺¹Alq^-1粒子,形成良好的欧姆接触,使得电子的注入效率大大提高.     

Rare Earth Centered Hybrid Materials: Tb<Superscript>3+</Superscript> Covalently Bonded with La<Superscript>3+</Superscript>, Gd<Superscript>3+</Superscript>, Y<Superscript>3+</Superscript> Through Sulfonamide Bridge and Luminescence Enhancement

The organic ligand 5-sulfosalicylic acid (SSA) is grafted by (3-aminopropyl) triethoxysilane (APTES) to achieve functionalized sulfonamide bridge (SSA-Si) which can both coordinate to Ln³⁺ to form luminescent center and link inorganic Si-O network through hydrolysis and condensation reaction with tetraethoxysilane (TEOS). Thus the organic–inorganic hybrid is obtained with sol-gel method. The organic polymer poly-methyl methacrylate (PMMA) acts as another precursor is prepared through the direct addition polymerization of MMA monomer in the presence of the initiator BPO (benzoyl peroxide). The two kinds of precursors are coordinated to the Ln³⁺ simultaneously to form organic–inorganic-polymeric hybrids which contain both inorganic Si-O-Si net and organic periodic C–C chains. In these complicated compounds we intercalate different ratios of Tb³⁺ and inert lanthanide ion (La³⁺, Gd³⁺, Y³⁺) and find that the introduction of the inert lanthanide ions can enhance the luminescence intensity. This enhancement phenomenon is called co-luminescence effect which is studied by emission spectra in this paper.     

Improved method to detect nitric oxide in biological systems

In this work an improved method is described for using organic solvent extracting to detect nitric oxide. The partition coefficients of the diethylthiocarbamate (DETC)-Fe²⁺ complex between different organic solvents and water, the signal intensity of the same NO trapping complex concentration in different organic solvents, and the extracting abilities of the organic solvents were determined. It was found that ethyl acetate was the optimal organic solvent. With ethyl acetate as extracting solvent, the (DETC)₂-Fe²⁺-NO complex was extracted from water phase to organic phase, and low concentration of nitric oxide in large volume could be detected by electron spin resonance (ESR) at room temperature. The ESR signal intensity had a good linear relationship with the concentration of nitric oxide, at a signal-to-noise ratio of 2. The detection threshold of this method was improved to lower than 50 nM, which was more sensitive than the usually used method. The (DETC)₂-Fe²⁺-NO complex was stable in the dark at 0–4°C, and there was little change after days. Nitric oxide produced by cardiomyocytes cultured in media and other biological systems was firstly detected with this method.     

Electrical conductivity and luminescence of metal-organic nanocomposites

We presented the results of experimental study of electrical and luminescence properties of planar nanocomposites based on gold island films and layers of efficient organic luminophores — aluminum (III) 8-hydroxyquinolinate (Alq₃) and europium β-diketonates [Eu(DBM)₃ bath, Eu(DBM)₃ phen, and Eu(DBM)₃]. The mechanisms of electroluminescence of such hybrid systems are discussed and the processes of luminescence excitation in the organic component of nanocomposites are considered in detail. It is shown that the spectral characteristics of europium β-diketonates are controlled by the Eu³⁺ ion fluorescence. The proposed mechanisms of nanocomposite electroluminescence are confirmed by the results of measurements of cathodoluminescence spectra of organic luminophores.     

Size effect on organic optoelectronics devices: Example of photovoltaic cell efficiency

Electromagnetic study of organic photovoltaic cells design shows that electrical parameters depend drastically on the active area geometry: we theoretically show that electrical parameters are altered when the cell length becomes greater than one centimeter. Experimental verification is provided with simple molecular heterojunction cells with areas from 0.03 to 0.78 cm².     

An alternative method to remove PEO-PPO-PEO template in organic-inorganic mesoporous nanocomposites by sulfuric acid extraction

Sulfuric acid is used as an extraction agent to remove PEO-PPO-PEO templates in the organic-inorganic mesoporous nanocomposites from the triconstituent co-assembly which includes the low-polymerized phenolic resins, TEOS and triblock copolymer F127. The XRD and TEM results show well ordered mesostructure after extraction with sulfuric acid. As followed from the N₂ sorption isotherms the extracted composites possess high surface areas (332-367 m²/g), large pore volumes (0.66-0.78 cm³/g), and large pore sizes (about 10.7 nm). The FT-IR analysis reveals almost complete elimination of triblock copolymer F127, and the maintenance of organic groups. This method shows potentials in removing templates from nanocomposites containing functional moieties.     

Diffusion- and T2-weighted MRI of closed-head injury in rats: A time course study and correlation with histology

Diffusion- and T₂-weighted MRI were used to evaluate changes in brain water characteristics following closed-head injury in rats. Images were collected within the first 2 h and at 24 h and 7 days following the traumatic event and then compared with histology. The ratios between the apparent diffusion coefficients (ADCs) of the traumatized tissues and normal brain tissues were significantly different from unity and were found to be 0.79 ± 0.25 (p < 0.01), 0.49 ± 0.33 (p < 0.0002), and 3.47 ± 1.36 (p < 10⁻⁶) at 1–2 h, 24 h, and 1 week after the trauma, respectively. In severe trauma, areas of hyperintensity which were not apparent on the T₂-weighted images could be detected on the diffusion-weighted images within 1–2 h after the trauma. At 24 h following the traumatic event, large areas of hyperintensity are observed in both types of images. One week following the trauma, the ADCs of the traumatized tissues (1.84 ± 0.69 × 10⁻⁵ cm²/s) are much larger than those of normal brain (0.57 ± 0.19 × 10⁻⁵ cm²/s) and approach the value of free water. At 7 days, the areas of hyperintensity in the T₂-weighted images seem to underestimate the injured areas found by histology. At this time point a good correlation is obtained between the areas of hypointensity observed on the diffusion-weighted images and the infarct areas obtained by histology (r = 0.88).