The role of water in the degradation process of paper using 1H HR-MAS NMR spectroscopy

2016 ◽  
Vol 18 (48) ◽  
pp. 33335-33343 ◽  
Author(s):  
Carmelo Corsaro ◽  
Domenico Mallamace ◽  
Sebastiano Vasi ◽  
Luciano Pietronero ◽  
Francesco Mallamace ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Dynamic Properties ◽  
Degradation Process ◽  
Mas Nmr ◽  
Cellulose Paper

We combine 1H HR MAS NMR and multi-component relaxation time to study the dynamic properties of the different components of cellulose–paper and water separately.

The Role of Si-H Functionality in Oxycarbide Glass Synthesis

1992 ◽  
Vol 271 ◽  
Author(s):  
Anant K. Singh ◽  
Carlo G. Pantano
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Analysis ◽  
Carbon Concentration ◽  
Mas Nmr ◽  
Silicon Oxycarbide ◽  
Total Carbon ◽  
Primary Interest ◽  
Hydrolysis And Condensation ◽  
Oxycarbide Glass

ABSTRACTSilicon oxycarbide gels and glasses were synthesized using various ratios of methyldimethoxysilane and TEOS. These gels and glasses were compared with those made from methyltrimethoxysilane and TEOS. The effect of the Si-H functionality in the methyldimethoxysilane was of primary interest. Hydrolysis and condensation processes were monitored using 1H and 29Si-NMR spectroscopy. The structures and the oxycarbide fractions of the glasses, obtained after heating the gels to 900°C in flowing argon, were investigated with 29si-MAS NMR. The total carbon and silicon contents of the glasses were determined using chemical analysis. The glasses covered the range of carbon concentration from ∼1 to 15%, while the silicon concentrations were constant at about 40%. The concentration of the oxycarbide species was enhanced in the glasses synthesized with the Si-H functionality in the precursor.

Crystallinity and structuring role of water in native and recrystallized starches by 13C CP-MAS NMR spectroscopy

1999 ◽  
Vol 39 (4) ◽  
pp. 327-339 ◽  
Author(s):  
M Paris ◽  
H Bizot ◽  
J Emery ◽  
J.Y Buzaré ◽  
A Buléon
Keyword(s):  
Nmr Spectroscopy ◽  
Mas Nmr ◽  
Cp Mas Nmr ◽  
13C Cp Mas Nmr

An NMR study on the mechanisms of freezing and melting of water confined in spherically mesoporous silicas SBA-16

2016 ◽  
Vol 18 (27) ◽  
pp. 18555-18562 ◽  
Author(s):  
Tatsuya Miyatou ◽  
Ryutaro Ohashi ◽  
Tomonori Ida ◽  
Shigeharu Kittaka ◽  
Motohiro Mizuno
Keyword(s):  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Dynamic Properties ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Mesoporous Silicas ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
H Nmr ◽  
Nmr Study

Thermodynamic and dynamic properties of water confined in mesoporous silica glass SBA-16 were investigated by DSC and 1,2H NMR spectroscopy and 2H NMR spin–lattice relaxation time as a function of pore size.

Progress in Structural Elucidation of Glasses by and 1B Satellite Transition NMR Spectroscopy

1995 ◽  
Vol 50 (4-5) ◽  
pp. 413-422 ◽  
Author(s):  
G. Kunath-Fandrei ◽  
D. Ehrt ◽  
C. Jäger
Keyword(s):  
Nmr Spectroscopy ◽  
Quadrupole Interaction ◽  
Chemical Shifts ◽  
Glass Structure ◽  
Structural Elucidation ◽  
Mas Nmr ◽  
Interaction Parameters ◽  
31P Mas Nmr ◽  
Satellite Transition

The structure of Na2O-Al2O3-B2O3 and Na2O-Al2O3-P2O5 glasses with 70 mole% B2O3 or P2O5 and varied Na/Al ratio is investigated using standard 31P MAS NMR and 27Al and UB Satellite Transition NMR spectroscopy. The role of the two network formers on the glass structure is discussed. For the AlOx units and BO3 and BO4 groups both chemical shifts and quadrupole interaction parameters including their distribution widths are reported. Besides this, the advantages of Satellite Transition spectroscopy are demonstrated both for 27A1 and 11B NMR

A kinetic study of the phase transformations in Al2O3 and Na2O · 6Al2O3 by a combined use of 27Al MAS NMR spectroscopy and x-ray diffraction: Importance of nucleation

1991 ◽  
Vol 6 (12) ◽  
pp. 2701-2705 ◽  
Author(s):  
S. Prabakar ◽  
K.J. Rao ◽  
C.N.R. Rao
Keyword(s):  
Nmr Spectroscopy ◽  
Phase Transformations ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
X Ray ◽  
Combined Use ◽  
27Al Mas Nmr ◽  
First Time ◽  
Kinetics Of

Phase transformations of Al2O3 and Na2O · 6Al2O3 prepared by the gel route have been investigated for the first time by 27Al MAS NMR spectroscopy in combination with x-ray diffraction. Of particular interest in the study is the kinetics of the γ → α and γ → β transformations, respectively, in these two systems. Analysis of the kinetic data shows the important role of nucleation in both these transformations.

Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1576-1586 ◽  
Author(s):  
Sara Pfister ◽  
Luca Sauser ◽  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen
Keyword(s):  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Core Region ◽  
Chlorin E6 ◽  
Polypropylene Glycol ◽  
Polymer Carriers ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Dynamic Methods ◽  
Derivatives Of

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

scholarly journals The Role of the Reactive Species Involved in the Photocatalytic Degradation of HDPE Microplastics Using C,N-TiO2 Powders

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 999 ◽  
Author(s):  
Aranza Denisse Vital-Grappin ◽  
Maria Camila Ariza-Tarazona ◽  
Valeria Montserrat Luna-Hernández ◽  
Juan Francisco Villarreal-Chiu ◽  
Juan Manuel Hernández-López ◽  
...  
Keyword(s):  
Wastewater Treatment Plants ◽  
Reaction System ◽  
Terrestrial Ecosystems ◽  
Degradation Process ◽  
Reactive Species ◽  
Hazardous Substances ◽  
Wide Range ◽  
Degradation Behaviors ◽  
Environmentally Friendly Process

Microplastics (MPs) are distributed in a wide range of aquatic and terrestrial ecosystems throughout the planet. They are known to adsorb hazardous substances and can transfer them across the trophic web. To eliminate MPs pollution in an environmentally friendly process, we propose using a photocatalytic process that can easily be implemented in wastewater treatment plants (WWTPs). As photocatalysis involves the formation of reactive species such as holes (h+), electrons (e−), hydroxyl (OH●), and superoxide ion (O2●−) radicals, it is imperative to determine the role of those species in the degradation process to design an effective photocatalytic system. However, for MPs, this information is limited in the literature. Therefore, we present such reactive species’ role in the degradation of high-density polyethylene (HDPE) MPs using C,N-TiO2. Tert-butanol, isopropyl alcohol (IPA), Tiron, and Cu(NO3)2 were confirmed as adequate OH●, h+, O2●− and e− scavengers. These results revealed for the first time that the formation of free OH● through the pathways involving the photogenerated e− plays an essential role in the MPs’ degradation. Furthermore, the degradation behaviors observed when h+ and O2●− were removed from the reaction system suggest that these species can also perform the initiating step of degradation.

scholarly journals Sampling Method Affects HR-MAS NMR Spectra of Healthy Caprine Brain Biopsies

Metabolites ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 38
Author(s):  
Annakatrin Häni ◽  
Gaëlle Diserens ◽  
Anna Oevermann ◽  
Peter Vermathen ◽  
Christina Precht
Keyword(s):  
Nmr Spectroscopy ◽  
Sampling Method ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
1H Nuclear Magnetic Resonance ◽  
Rapid Changes ◽  
Tissue Degradation ◽  
Angle Spinning

The metabolic profiling of tissue biopsies using high-resolution–magic angle spinning (HR-MAS) 1H nuclear magnetic resonance (NMR) spectroscopy may be influenced by experimental factors such as the sampling method. Therefore, we compared the effects of two different sampling methods on the metabolome of brain tissue obtained from the brainstem and thalamus of healthy goats by 1H HR-MAS NMR spectroscopy—in vivo-harvested biopsy by a minimally invasive stereotactic approach compared with postmortem-harvested sample by dissection with a scalpel. Lactate and creatine were elevated, and choline-containing compounds were altered in the postmortem compared to the in vivo-harvested samples, demonstrating rapid changes most likely due to sample ischemia. In addition, in the brainstem samples acetate and inositols, and in the thalamus samples ƴ-aminobutyric acid, were relatively increased postmortem, demonstrating regional differences in tissue degradation. In conclusion, in vivo-harvested brain biopsies show different metabolic alterations compared to postmortem-harvested samples, reflecting less tissue degradation. Sampling method and brain region should be taken into account in the analysis of metabolic profiles. To be as close as possible to the actual situation in the living individual, it is desirable to use brain samples obtained by stereotactic biopsy whenever possible.

Sign in / Sign up

Export Citation Format

Share Document