Solid-State Nuclear Magnetic Resonance

Dybowski, Cecil; Bai, Shi; Bramer, Scott Van

doi:10.1021/ac0201981

Cited by 11 publications

(2 citation statements)

References 153 publications

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“…For this regards, many outstanding review papers or books have been reported for the last few years. 124,[126][127][128][129][130][131][132] In these reports, the fundamental principles, characteristics and applications of ssNMR spectroscopy have been well described, and therefore these have purposely been avoided here.…”

Section: Ivv Spectroscopic Analysesmentioning

confidence: 99%

Methods to characterize the structure of food powders – a review

Truong

Bhandari

2017

Bioscience, Biotechnology, and Biochemistry

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Food powders can exist in amorphous, crystalline or mixed structure depending on the order of molecular arrangement in the powder particle matrices. In food production, the structure of powders has a greatly effect on their stability, functionality, and applicability. The undesirable structure of powders can be accidentally formed during production. Therefore, characterization of powder structure as well as quantification of amorphous-crystalline proportions presenting in the powders are essential to control the quality of products during storage and further processing. For these purposes, many analytical techniques with large differences in the degree of selectivity and sensitivity have been developed. In this review, differences in the structure of food powders are described with a focus being placed on applications of amorphous powders. Essentially, applicability of common analytical techniques including X-ray, microscopic, vapor adsorption, thermal, and spectroscopic approaches for quantitative and qualitative structural characterization of food powders is also discussed.

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Section: Ivv Spectroscopic Analysesmentioning

confidence: 99%

Methods to characterize the structure of food powders – a review

Truong

Bhandari

2017

Bioscience, Biotechnology, and Biochemistry

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“…Solidstate nuclear magnetic resonance (NMR) and X-ray diffraction (XRD) are wellestablished tools for the characterization of zeolites and zeotype materials. [34][35][36][37][38][39][40] XRD quantifies the fraction of the materials exhibiting Bragg crystallinity, while 29 Si MAS NMR detects crystalline as well as amorphous non-framework material. 41 Recently, the creation of silanol nests, and hydroxyl nets associated to Al-OH in the framework of Y zeolite after alkaline treatment have been observed by using 27 Al{ 1 H} TRAPDOR experiments.…”

Section: Introductionmentioning

confidence: 99%

Hierarchization of USY Zeolite by NH₄OH. A Postsynthetic Process Investigated by NMR and XRD

et al. 2014

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Ammonia treatment of USY zeolite has led to a new hierarchical material. The local and global structural changes during the transformation have been monitored by XRD and by 1 H, 29 Si, and 27 Al solid-state NMR. A wealth of 1D and 2D NMR protocols were applied, including 1 H DQ-SQ, 27 Al MQMAS, 29 Si MAS and CPMAS as well as 1 H-29 Si HETCOR. The effects of aqueous ammonia treatment, different thermal post-treatments and rehydration were studied. An increasing loss of crystallinity was observed upon increasing duration of ammonia treatment. Under the experimental conditions a few percent of silica was lost into solution and no loss of aluminum was observed. But, increasing numbers of silanol groups were detected. The progressive transformation induces formation of mesopores, reduction of the fraction of the sample exhibiting Bragg crystallinity and apparition of a dense, amorphous aluminosilicate phase. The latter contains ammonium ions and strongly bound water which both are resistant to thermal decomposition up to 350 °C. After about 24 hours of treatment the zeolite fraction has been completely transformed into the amorphous phase. At intermediate stages a complexhierarchical material is obtained with mesopores and zeolitic micropores next to a dense amorphous aluminosilicate, containing ammonium ions, highly structured water and silanols nests.

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