Efficient CH-Group Selection and Identification in <sup>13</sup>C Solid-State NMR by Dipolar DEPT and <sup>1</sup>H Chemical-Shift Filtering

Schmidt‐Rohr, Klaus; Jd, Mao

doi:10.1021/ja027362m

Cited by 66 publications

(96 citation statements)

References 25 publications

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“…A few techniques can identify the nature of the atoms bonded to C in a material: 13 C-Nuclear Magnetic Resonance (Casabianca et al, 2010), including Distortionless Enhancement by Polarization Transfer Spectra (Schmidt-Rohr and Mao, 2002), and Near-Edge X-ray Absorption Fine Structure spectroscopy (Braun, 2005). However, C atoms can be well bonded to C atoms even in quite banal organic molecules like coronene or neopentane, for instance.…”

Section: Measurements Of Ec and Ocmentioning

confidence: 99%

Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

et al. 2012

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Abstract. Soot, which is produced from biomass burning and the incomplete combustion of fossil and biomass fuels, has been linked to regional and global climate change and to negative health problems. Scientists measure the properties of soot using a variety of methods in order to quantify source emissions and understand its atmospheric chemistry, reactivity under emission conditions, interaction with solar radiation, influence on clouds, and health impacts. A major obstacle currently limiting progress is the absence of established standards or reference materials for calibrating the many instruments used to measure the various properties of soot.The current state of availability and practicability of soot standard reference materials (SRMs) was reviewed by a group of 50 international experts during a workshop in June of 2011. The workshop was convened to summarize the current knowledge on soot measurement techniques, identify the measurement uncertainties and limitations related to the lack of soot SRMs, and identify attributes of SRMs that, if developed, would reduce measurement uncertainties. The workshop established that suitable SRMs are available for calibrating some, but not all, measurement methods. The community of users of the single-particle soot-photometer (SP2), an instrument using laser-induced incandescence, identified a suitable SRM, fullerene soot, but users of instruments that measure light absorption by soot collected on filters did not. Similarly, those who use thermal optical analysis (TOA) to analyze the organic and elemental carbon components of soot were not satisfied with current SRMs. The workshop, and subsequent, interactive discussions, produced a number of recommendations for the development of new SRMs, and their implementation, that would be suitable for the different soot measurement methods.

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Section: Measurements Of Ec and Ocmentioning

confidence: 99%

Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

et al. 2012

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“…The difference between the dephased and undephased 13 C NMR spectra shows only carbons connected to nitrogen. Other NMR spectral editing methods separate overlapping resonances of various chemical groups (Schmidt-Rohr and Mao, 2002b). The method has been tested and calibrated on model compounds (Schmidt-Rohr and Mao, 2002a).…”

Section: Yield Trends and Som Quality Under Intensive Rice Croppingmentioning

confidence: 99%

Chemical stabilization of soil organic nitrogen by phenolic lignin residues in anaerobic agroecosystems

Olk¹,

Cassman

Schmidt‐Rohr

et al. 2006

Soil Biology and Biochemistry

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110

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This review summarizes independent reports of yield decreases in several agricultural systems that are associated with repeated cropping under wet or submerged soil conditions. Crop and soil data from most of these agroecosystems have led researchers to attribute yield decreases to a reduction in crop uptake of N mineralized from soil organic matter (SOM). These trends are most evident in several long-term field experiments on continuous lowland rice systems in the Philippines, but similar trends are evident in a continuous rice rotation in Arkansas, USA and with no-till cropping systems in North American regions with cool, wet climatic conditions in Spring. Soil analyses from some of these systems have found an accumulation of phenolic lignin compounds in SOM. Phenolic compounds covalently bind nitrogenous compounds into recalcitrant forms in laboratory conditions and occurrence of this chemical immobilization under field conditions would be consistent with field observations of reduced soil N supply. However, technological shortcomings have precluded its demonstration for naturally formed SOM. Through recent advances in nuclear magnetic resonance spectroscopy, agronomically significant quantities of lignin-bound N were found in a triple-cropped rice soil in the Philippines. A major research challenge is to demonstrate in the anaerobic agroecosystems that these lignin residues bind sufficient quantities of soil N to cause the observed yield decreases. A key objective will be to elucidate the cycling dynamics of lignin-bound N relative to the seasonal pattern of crop N demand. Anaerobic decomposition of crop residues may be the key feature of anaerobic cropping systems that promotes the accumulation of phenolic lignin residues and hence the covalent binding of soil N. Potential mitigation options include improved timing of applied N fertilizer, which has already been shown to reverse yield decreases in tropical rice, and aerobic decomposition of crop residues, which can be accomplished through field drainage or timing of tillage operations. Future research will evaluate whether aerobic decomposition promotes the formation of phenol-depleted SOM and greater in-season N mineralization, even when the soil is otherwise maintained under flooded conditions during the growing season. r

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“…During the recent years, many advanced solid-state 13 C NMR techniques have been developed, improved, and applied for characterizing complexity of NOM in algaes, plants, soils, sediments, and kerogens [23,43]; Mao and Schmidt-Rohr [24][25][26], Mao et al [27][28][29]. These advanced solid-state NMR techniques include 13 C DP/ MAS NMR, quantitative DP/MAS plus dipolar dephasing, 13 C chemical-shift anisotropy filter (CSA), and CH, CH 2 spectral editing [28].…”

Section: Introductionmentioning

confidence: 99%

Composition and structure of natural organic matter through advanced nuclear magnetic resonance techniques

Zhang

Duan

Huang

et al. 2017

Chem. Biol. Technol. Agric.

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Natural organic matter (NOM) plays important roles in biological, chemical, and physical processes within the terrestrial and aquatic ecosystem. Despite its importance, a clear and exhaustive knowledge on NOM chemistry still lacks. Aiming to prove that advanced solid-state 13 C nuclear magnetic resonance (NMR) techniques may contribute to fill such a gap, in this paper we reported relevant examples of its applicability to NOM components, such as biomass, deposition material, sediments, and kerogen samples. It is found that nonhydrolyzable organic carbons (NHC), chars, and polymethylene carbons are important in the investigated samples. The structure of each of the NHC fractions is similar to that of kerogens, highlighting the importance of selective preservation of NOM to the kerogen origin in the investigated aquatic ecosystems. Moreover, during the artificial maturation experiments of kerogen, the chemical and structural characteristics such as protonated aromatic, nonprotonated carbons, and aromatic cluster size play important roles in the origin and variation of nanoporosity during kerogen maturation.

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Efficient CH-Group Selection and Identification in ¹³C Solid-State NMR by Dipolar DEPT and ¹H Chemical-Shift Filtering

Cited by 66 publications

References 25 publications

Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

Chemical stabilization of soil organic nitrogen by phenolic lignin residues in anaerobic agroecosystems

Composition and structure of natural organic matter through advanced nuclear magnetic resonance techniques

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Efficient CH-Group Selection and Identification in 13C Solid-State NMR by Dipolar DEPT and 1H Chemical-Shift Filtering

Cited by 66 publications

References 25 publications

Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

Chemical stabilization of soil organic nitrogen by phenolic lignin residues in anaerobic agroecosystems

Composition and structure of natural organic matter through advanced nuclear magnetic resonance techniques

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Product

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Efficient CH-Group Selection and Identification in ¹³C Solid-State NMR by Dipolar DEPT and ¹H Chemical-Shift Filtering