Latex state NMR spectroscopy and field gradient fast magic angle spinning solid state NMR spectro... more Latex state NMR spectroscopy and field gradient fast magic angle spinning solid state NMR spectroscopy were used for structural characterization of vulcanized butadiene rubber and vulcanized natural rubber. High resolution NMR spectra for elastomers were achieved either through Brownian motion of a latex dispersion or fast magic angle spinning for a solid. Sequence distribution of cis-1,4-, trans-1,4-and 1,2-butadiene units was investigated for polybutadiene through latex state NMR spectroscopy. Crosslinking junctions of vulcanized natural rubber were analyzed by field gradient fast magic angle spinning solid state NMR spectroscopy.
The natural abundant two-dimensional exchange 13 C NMR revealed the very close proximity between ... more The natural abundant two-dimensional exchange 13 C NMR revealed the very close proximity between the carboxyl carbon of PMAA and carbonyl carbon of PVAc in the miscible PMAA/PVAc = 3/1 blend. The estimated distance between the CO carbons is approximately 0.37 nm. This close distance is induced by a strong hydrogen bond between the hydrogen of carboxyl group for PMAA and the oxygen of carbonyl group for PVAc. The molecular mechanics (MM) calculation reveals that the distance of the hydrogen bond between the hydrogen of the carboxyl group and the oxygen of the carbonyl group is approximately 0.2 nm by fixing the intermolecular (inter-polymer) CC distance between the CO carbons to be 0.37 nm. This value is reasonable for the very strong hydrogen bonding interaction. This interaction makes the 13 C chemical shift value of PVAc carbonyl carbon peak toward lower field by 4 ppm and that of PMAA carboxyl carbon peak to change toward upper field by 4 ppm. The MM calculation also showed that the distance between the backbone carbons of PMAA and PVAc is less than 1 nm. This very cross proximity for the interacted region is important to create the homogenous PMAA/PVAc blends on a scale of 2-5 nm.
Preface to the Special Issue Simulation and training have now become indispensable strategies in ... more Preface to the Special Issue Simulation and training have now become indispensable strategies in many businesses, industries, and lhe mili tary to accomplish their missions and objectives. In fac t, the investment in si mulation technologies and train ing strategies by organizations is over $300 billion a year. In spite of this huge investment, can we calculate its return? Do we know whether our training strategies are working or yieldi ng the desired learning and performance outcomes? Do we routinely conduct trai ning evaluations and, if so, how? Every training textbook or instruction model espouses the importance and necessity of training evaluations. Although those in the field cannot deny their importance and value, such evaluations are more talked about than actually conducted. We all pay lip service to the criticality of training evaluations, but we seldom perform them. Therefore, this subject is the focus of this special issue. The purpose of the special issue is twofold. First, we want to document recent theories, research, methods, and approaches being developed in this area. The articles in this issue arc a representative sample of the research being conducted, pri marily by the military, in trai ning evaluations. A second purpose is to convince those in charge of designing, delivering, implementing, and managing training systems of the value of conducting such evaluations. We hope that scientists and those in practice will sec that additional tools and guideli nes fo r facilitati ng the conduct of training evaluations arc now available and th at such evaluations can be "built in" as a regular component when designi ng training and simulation systems. Further, we hope to encourage scientists to continue to conduct research in this area and to develop tools, methods, principles, and guidelines that practitioners can use and apply. Finally, it is our hope that, with this issue, a new era in military trainingthe systematic and routine conduct of training evaluationswill be launched. We would like to thank Marty Wiskoff fo r his support and encouragement in the completion of this issue. We would also like to express our appreciation to the many reviewers who provided useful comments to the authors of the articles. Finally, we thank those authors for their patience duri ng the long review process. We believe that, in the end, all of the hard work paid off!
Abstract The effect of 1 H spin diffusion on the relaxation process in poly(γ-methyl- l -glutamat... more Abstract The effect of 1 H spin diffusion on the relaxation process in poly(γ-methyl- l -glutamate)/poly(vinylpyrrolidone) (PMLG/PVP) blends has been studied by CP/MAS 13 C NMR spectroscopy. The domain sizes of PMLG/PVP blends have been estimated. The 70 30 PMLG/PVP blend is found to be homogeneous on a scale of 10–20 nm from the examination of 1 H relaxation, while the other blends are heterogeneous on that scale. The Goldman-Shen experiment combined with the CP/MAS 13 C NMR technique provides information on the mean width of PMLG domain in the PMLG/PVP blends. The mean width of PMLG domain in the 70 30 PMLG/PVP blend is estimated to be about 6.8 nm.
Various types of silica, silica gel, fumed silicas and fused silica were added to polypropylene a... more Various types of silica, silica gel, fumed silicas and fused silica were added to polypropylene and polyethylene oxide to determine their flame retardant effectiveness and mechanisms. Polypropylene was chosen as a non-char-forming thermoplastic and polyethylene oxide was chosen as ...
The 13C NMR spectrum of regioirregular polypropylene containing up to 40 mol % of inverted propyl... more The 13C NMR spectrum of regioirregular polypropylene containing up to 40 mol % of inverted propylene units was assigned using the 2D INADEQUATE technique, the INEPT technique, and 13C chemical shift calculations based on the NMR y-effect and the application of the rotational isomeric state model and also on the additive rules for 13C chemical shifts of methyl-substituted alkanes. The presence of four kinds of sequences containing head-to-head and/or tail-to-tail units in the sample was confirmed. The 13C-I3C connectivities of the 2D INADEQUATE spectrum were extremely useful in the assignment of overlapping peaks as well as the identification of several such sequences. The peaks were assigned to each carbon in these sequences by taking tacticity into account. There is exclusively a meso head-to-head unit in the sequence where a single inverted unit is contained in several head-to-tail units.
Latex state NMR spectroscopy and field gradient fast magic angle spinning solid state NMR spectro... more Latex state NMR spectroscopy and field gradient fast magic angle spinning solid state NMR spectroscopy were used for structural characterization of vulcanized butadiene rubber and vulcanized natural rubber. High resolution NMR spectra for elastomers were achieved either through Brownian motion of a latex dispersion or fast magic angle spinning for a solid. Sequence distribution of cis-1,4-, trans-1,4-and 1,2-butadiene units was investigated for polybutadiene through latex state NMR spectroscopy. Crosslinking junctions of vulcanized natural rubber were analyzed by field gradient fast magic angle spinning solid state NMR spectroscopy.
The natural abundant two-dimensional exchange 13 C NMR revealed the very close proximity between ... more The natural abundant two-dimensional exchange 13 C NMR revealed the very close proximity between the carboxyl carbon of PMAA and carbonyl carbon of PVAc in the miscible PMAA/PVAc = 3/1 blend. The estimated distance between the CO carbons is approximately 0.37 nm. This close distance is induced by a strong hydrogen bond between the hydrogen of carboxyl group for PMAA and the oxygen of carbonyl group for PVAc. The molecular mechanics (MM) calculation reveals that the distance of the hydrogen bond between the hydrogen of the carboxyl group and the oxygen of the carbonyl group is approximately 0.2 nm by fixing the intermolecular (inter-polymer) CC distance between the CO carbons to be 0.37 nm. This value is reasonable for the very strong hydrogen bonding interaction. This interaction makes the 13 C chemical shift value of PVAc carbonyl carbon peak toward lower field by 4 ppm and that of PMAA carboxyl carbon peak to change toward upper field by 4 ppm. The MM calculation also showed that the distance between the backbone carbons of PMAA and PVAc is less than 1 nm. This very cross proximity for the interacted region is important to create the homogenous PMAA/PVAc blends on a scale of 2-5 nm.
Preface to the Special Issue Simulation and training have now become indispensable strategies in ... more Preface to the Special Issue Simulation and training have now become indispensable strategies in many businesses, industries, and lhe mili tary to accomplish their missions and objectives. In fac t, the investment in si mulation technologies and train ing strategies by organizations is over $300 billion a year. In spite of this huge investment, can we calculate its return? Do we know whether our training strategies are working or yieldi ng the desired learning and performance outcomes? Do we routinely conduct trai ning evaluations and, if so, how? Every training textbook or instruction model espouses the importance and necessity of training evaluations. Although those in the field cannot deny their importance and value, such evaluations are more talked about than actually conducted. We all pay lip service to the criticality of training evaluations, but we seldom perform them. Therefore, this subject is the focus of this special issue. The purpose of the special issue is twofold. First, we want to document recent theories, research, methods, and approaches being developed in this area. The articles in this issue arc a representative sample of the research being conducted, pri marily by the military, in trai ning evaluations. A second purpose is to convince those in charge of designing, delivering, implementing, and managing training systems of the value of conducting such evaluations. We hope that scientists and those in practice will sec that additional tools and guideli nes fo r facilitati ng the conduct of training evaluations arc now available and th at such evaluations can be "built in" as a regular component when designi ng training and simulation systems. Further, we hope to encourage scientists to continue to conduct research in this area and to develop tools, methods, principles, and guidelines that practitioners can use and apply. Finally, it is our hope that, with this issue, a new era in military trainingthe systematic and routine conduct of training evaluationswill be launched. We would like to thank Marty Wiskoff fo r his support and encouragement in the completion of this issue. We would also like to express our appreciation to the many reviewers who provided useful comments to the authors of the articles. Finally, we thank those authors for their patience duri ng the long review process. We believe that, in the end, all of the hard work paid off!
Abstract The effect of 1 H spin diffusion on the relaxation process in poly(γ-methyl- l -glutamat... more Abstract The effect of 1 H spin diffusion on the relaxation process in poly(γ-methyl- l -glutamate)/poly(vinylpyrrolidone) (PMLG/PVP) blends has been studied by CP/MAS 13 C NMR spectroscopy. The domain sizes of PMLG/PVP blends have been estimated. The 70 30 PMLG/PVP blend is found to be homogeneous on a scale of 10–20 nm from the examination of 1 H relaxation, while the other blends are heterogeneous on that scale. The Goldman-Shen experiment combined with the CP/MAS 13 C NMR technique provides information on the mean width of PMLG domain in the PMLG/PVP blends. The mean width of PMLG domain in the 70 30 PMLG/PVP blend is estimated to be about 6.8 nm.
Various types of silica, silica gel, fumed silicas and fused silica were added to polypropylene a... more Various types of silica, silica gel, fumed silicas and fused silica were added to polypropylene and polyethylene oxide to determine their flame retardant effectiveness and mechanisms. Polypropylene was chosen as a non-char-forming thermoplastic and polyethylene oxide was chosen as ...
The 13C NMR spectrum of regioirregular polypropylene containing up to 40 mol % of inverted propyl... more The 13C NMR spectrum of regioirregular polypropylene containing up to 40 mol % of inverted propylene units was assigned using the 2D INADEQUATE technique, the INEPT technique, and 13C chemical shift calculations based on the NMR y-effect and the application of the rotational isomeric state model and also on the additive rules for 13C chemical shifts of methyl-substituted alkanes. The presence of four kinds of sequences containing head-to-head and/or tail-to-tail units in the sample was confirmed. The 13C-I3C connectivities of the 2D INADEQUATE spectrum were extremely useful in the assignment of overlapping peaks as well as the identification of several such sequences. The peaks were assigned to each carbon in these sequences by taking tacticity into account. There is exclusively a meso head-to-head unit in the sequence where a single inverted unit is contained in several head-to-tail units.
Uploads
Papers by Atsushi Asano