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1.
Dalton Trans ; 52(18): 6152-6165, 2023 May 09.
Article in English | MEDLINE | ID: mdl-37073995

ABSTRACT

A series of medium- and long-chain zinc carboxylates (zinc octanoate, zinc nonanoate, zinc decanoate, zinc undecanoate, zinc dodecanoate, zinc pivalate, zinc stearate, zinc palmitate, zinc oleate, and zinc azelate) was analyzed by ultra-high-field 67Zn NMR spectroscopy up to 35.2 T, as well as 13C NMR and FTIR spectroscopy. We also report the single-crystal X-ray diffraction structures of zinc nonanoate, zinc decanoate, and zinc oleate-the first long-chain carboxylate single-crystals to be reported for zinc. The NMR and X-ray diffraction data suggest that the carboxylates exist in three distinct geometric groups, based on structural and spectroscopic parameters. The ssNMR results presented here present a future for dynamic nuclear polarization (DNP)-NMR-based minimally invasive methods for testing artwork for the presence of zinc carboxylates.

2.
ACS Nano ; 16(8): 12024-12035, 2022 Aug 23.
Article in English | MEDLINE | ID: mdl-35849721

ABSTRACT

Increasing demand for effective energy conversion materials and devices has renewed interest in semiconductors comprised of earth-abundant and biocompatible elements. Alkaline-earth sulfides doped with rare earth ions are versatile optical materials. However, relatively little is known about controlling the dimensionality, surface chemistry, and inherent optical properties of the undoped versions of alkaline-earth mono- and polychalcogenides. We describe the colloidal synthesis of alkaline-earth chalcogenide nanocrystals through the reaction of metal carboxylates with carbon disulfide or selenourea. Systematic exploration of the synthetic phase space allows us to tune particle sizes over a wide range using a mixture of commercially available carboxylate precursors. Solid-state NMR spectroscopy confirms the phase purity of the selenide compositions. Surface characterization reveals that bridging carboxylates and amines preferentially terminate the surface of the nanocrystals. While these materials are colloidally stable in the mother solution, the selenides are susceptible to oxidation over time, eventually degrading to selenium metal through polyselenide intermediates. As part of these investigations, we have developed the colloidal syntheses of barium di- and triselenides, two among few reported nanocrystalline alkaline-earth polychalcogenides. Electronic structure calculations reveal that both materials are indirect band gap semiconductors. The colloidal chemistry presented here may enable the synthesis of more complex, multinary chalcogenide materials containing alkaline-earth elements.

3.
Sci Rep ; 10(1): 18320, 2020 Oct 27.
Article in English | MEDLINE | ID: mdl-33110102

ABSTRACT

The quantitative evaluation of the three-dimensional (3D) morphology of porous composite materials is important for understanding mass transport phenomena, which further impact their functionalities and durability. Reactive porous paint materials are composites in nature and widely used in arts and technological applications. In artistic oil paintings, ambient moisture and water and organic solvents used in conservation treatments are known to trigger multiple physical and chemical degradation processes; however, there is no complete physical model that can quantitatively describe their transport in the paint films. In the present study, model oil paints with lead white (2PbCO3·Pb(OH)2) and zinc white (ZnO) pigments, which are frequently found in artistic oil paintings and are associated with the widespread heavy metal soap deterioration, were studied using synchrotron X-ray nano-tomography and unilateral nuclear magnetic resonance. This study aims to establish a relationship among the paints' compositions, the 3D morphological properties and degradation. This connection is crucial for establishing reliable models that can predict transport properties of solvents used in conservation treatments and of species involved in deterioration reactions, such as soap formation.

4.
Magn Reson Chem ; 58(9): 798-811, 2020 09.
Article in English | MEDLINE | ID: mdl-32247290

ABSTRACT

Heavy metal carboxylate or soap formation is a widespread deterioration problem affecting oil paintings and other works of art bearing oil-based media. Lead soaps are prevalent in traditional oil paintings because lead white was the white pigment most frequently chosen by old masters for the paints and in some cases for the ground preparations, until the development of other white pigments from approximately the middle of the 18th century on, and because of the wide use of lead-tin yellow. In the latter part of the 19th century, lead white began to be replaced by zinc white. The factors that influence soap formation have been the focus of intense study starting in the late 1990s. Since 2014, nuclear magnetic resonance (NMR) studies have contributed a unique perspective on the issue by providing chemical, structural, and dynamic information about the species involved in the process, as well as the effects of environmental conditions such as relative humidity and temperature on the kinetics of the reaction(s). In this review, we explore recent insights into soap formation gained through solid-state NMR and single-sided NMR techniques.

5.
Chemphyschem ; 21(1): 113-119, 2020 01 03.
Article in English | MEDLINE | ID: mdl-31536159

ABSTRACT

Heavy metal carboxylate degradation severely affects thousands of oil paintings. Relative humidity has been reported to accelerate the rate of the reactions. To evaluate its role further, water diffusion and molecular mobility of protons in linseed oil-based lead white paints were studied by unilateral NMR and 1 H HRMAS spectroscopy. The results indicate that exposure to high %RH for relatively long times affects the dynamics of the oil paint's mobile fraction and that the effect is more pronounced as the thickness of the film increases. It was found that the paint can absorb appreciable amounts of water and has a porosity of approximately 6 % available for the diffusion of water, for which a regime of restricted diffusion was observed. Furthermore, the presence of bound and free-moving water, due to the possible formation of hydrated ionic-group clusters, supports the hypothesis of a polymeric/ionomeric network, as well as regions of essentially water free to move as in the bulk. The findings allow a better understanding of the role of water as a factor activating the degradation process in linseed oil-based lead white paints.

6.
J Nurs Care Qual ; 31(1): 40-5, 2016.
Article in English | MEDLINE | ID: mdl-26121052

ABSTRACT

Many fall prevention strategies exist with some degree of effectiveness. Evidence to support 1 unique bundling of strategies is limited. The purpose of this article is to describe a staff-driven quality improvement initiative to develop a video in partnership with patients and families to prevent falls when hospitalized. Since the video's release, the fall rate has decreased by 29.4%.


Subject(s)
Accidental Falls/prevention & control , Nursing Staff , Quality Improvement , Video Recording/methods , Humans , Michigan , Patient Safety , Program Evaluation , Video Recording/standards
7.
Nature ; 418(6893): 37-8, 2002 Jul 04.
Article in English | MEDLINE | ID: mdl-12097899

ABSTRACT

How left right handedness originates in the body plan of the developing vertebrate embryo is a subject of considerable debate. In mice, a left right bias is thought to arise from a directional extracellular flow (nodal flow) that is generated by dynein-dependent rotation of monocilia on the ventral surface of the embryonic node. Here we show that the existence of node monocilia and the expression of a dynein gene that is implicated in ciliary function are conserved across a wide range of vertebrate classes, indicating that a similar ciliary mechanism may underlie the establishment of handedness in all vertebrates.


Subject(s)
Body Patterning , Cilia/physiology , Dyneins/metabolism , Embryo, Mammalian/cytology , Embryo, Mammalian/embryology , Embryo, Nonmammalian , Vertebrates/embryology , Animals , Axonemal Dyneins , Chick Embryo , Conserved Sequence , Dyneins/genetics , Embryo, Mammalian/metabolism , Gastrula/cytology , Gastrula/metabolism , Gene Expression Profiling , Gene Expression Regulation, Developmental , Mice , Organizers, Embryonic/embryology , Organizers, Embryonic/metabolism , Signal Transduction , Vertebrates/genetics , Xenopus/embryology , Xenopus/genetics , Zebrafish/embryology , Zebrafish/genetics , Zebrafish Proteins
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