456 research outputs found
Dementia Caregiving Research: Expanding and Reframing the Lens of Diversity, Inclusivity, and Intersectionality
This forum expands and reframes the lens of dementia caregiving research among diverse racial and ethnic groups to better understand the unique needs, stressors, and strengths of multicultural and racial-ethnic family caregivers in the United States. By providing more diverse and inclusive knowledge on caregiving to older adults in the United States, we can create a new path forward with regards to caregiving research. Throughout the article, major questions and answers are supported by critiquing some of the caregiving literature. Discussions are provided to help create inclusive ways of conceptualizing caregiving research and using methodological approaches to reflect the diversity of caregivers and care recipients in the United States. Expanding and reframing the conceptual and methodological lens of diversity, inclusivity and intersectionality can provide evidence to support effective policy, practice, and care in addressing the needs of diverse groups of caregivers and older adults living with dementia
Structure-properties correlations in divalent metal phosphonates
Crystalline metal phosphonates may offer acidic sites, structural flexibility and guest molecules (H2O, heterocyclics, etc.) which can act as proton carriers. In addition, some frameworks are also amenable for post‐synthesis modifications in order to enhance desired properties [1,2].
In this work, we present the synthesis and structural characterization of two hydroxyphosphonoacetates hybrids based on magnesium, [Mg5(O3PCHOHCOO)2(HO3PCHOHCOO)2·8H2O] [Mg5(HPAA)2(H1HPAA)2·8H2O], and zinc, [Zn6K(O3PCHOHCOO)4(OH)·6.5H2O] [Zn6K(HPAA)4(OH)·6.5H2O]. Both solids present three-dimensional frameworks and their crystal structures were solved ab initio from X-ray powder diffraction. The proton conductivity of [Zn6K(HPAA)4(OH)·6.5H2O] as well as ammonia derivatives of M(II)(HO3PCHOHCOO)·2H2O [M(II)=Zn, Mg] will be reported and discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. FQM-1656; MAT2013-41836-
Achieving Health Equity in Embedded Pragmatic Trials for People Living with Dementia and Their Family Caregivers
Embedded pragmatic clinical trials (ePCTs) advance research on Alzheimer's disease/Alzheimer's disease and related dementias (AD/ADRD) in real-world contexts; however, health equity issues have not yet been fully considered, assessed, or integrated into ePCT designs. Health disparity populations may not be well represented in ePCTs without special efforts to identify and successfully recruit sites of care that serve larger numbers of these populations. The National Institute on Aging (NIA) Imbedded Pragmatic Alzheimer's disease (AD) and AD-Related Dementias (AD/ADRD) Clinical Trials (IMPACT) Collaboratory's Health Equity Team will contribute to the overall mission of the collaboratory by developing and implementing strategies to address health equity in the conduct of ePCTs and ensure the collaboratory is a national resource for all Americans with dementia. As a first step toward meeting these goals, this article reviews what is currently known about the inclusion of health disparities populations of people living with dementia (PLWD) and their caregivers in ePCTs, highlights unique challenges related to health equity in the conduct of ePCTs, and suggests priority areas in the design and implementation of ePCTs to increase the awareness and avoidance of pitfalls that may perpetuate and magnify healthcare disparities
Proton conductivity of multifunctional metal phosphonate frameworks
Metal phosphonates exhibit attractive characteristics for proton conductivity, such as tunable functionality, chemical and thermal stability and the existence of H-bond networks with acidic protons within their structure.1
In the present work, we examine the relationship between crystal structure and proton conductivity for several metal (mono-, di- and tri-valent) phosphonates containing rigid: (5-(dihydroxyphosphoryl)isophthalic acid, PiPhtA and 2-hydroxyphosphonoacetic acid, HPAA) or flexible: (hexa- or octamethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid, H8HDTMP or H8ODTMP) multifunctional ligands. The crystalline hybrid derivatives prepared show a great structural diversity, from 1D to 3D open-frameworks possessing hydrogen-bonded water molecules and phosphonic and carboxylic acid groups. The rigid 3D framework of Ca-PiPhtA, that exhibits a proton conductivity of 5.7•10-4 S/cm as synthesized, transforms into a layered compound upon exposure to ammonia vapors2 with increased proton conductivity (6.6•10-3 S/cm). The flexible frameworks of magnesium or lanthanide phosphonates, with 1D channels, present conductivities higher than 10-3 S/cm. Their activation energies fall in the range corresponding to a Grotthuss mechanism.3,4 For M(I)-HPAA solids conductivities up to 5.6•10-3 S/cm were measured.
References
1. P. Ramaswamy, N.E. Wong, G.K.H. Shimizu, Chem. Soc. Rev. 43 (2014) 5913.
2. M. Bazaga-García, R.M.P. Colodrero, M. Papadaki, P. Garczarek, J. Zoń, P. Olivera-Pastor, E.R. Losilla, L. León-Reina, M.A.G. Aranda, D. Choquesillo-Lazarte, K.D. Demadis, A. Cabeza, J. Amer. Chem. Soc. 136 (2014) 5731.
3. R.M.P. Colodrero, P. Olivera-Pastor, E.R. Losilla, D. Hernández-Alonso, M.A.G. Aranda, L. Leon-Reina, J. Rius, K.D. Demadis, B. Moreau, D. Villemin, M. Palomino, F. Rey, A. Cabeza, Inorg. Chem. 51 (2012) 7689.
4. R.M.P. Colodrero, P. Olivera-Pastor, E.R. Losilla, M.A.G. Aranda, L. Leon-Reina, M. Papadaki, A.C. McKinlay, R.E. Morris, K.D. Demadis, A. Cabeza, Dalton Trans. 41 (2012) 4045.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Junta de Andalucía, Proyecto Excelencia FQM-1656. Ministerio de Economía y Competitividad, MAT2013-41836-
Photocatalytic behavior of phosphonate-based hybrid materials on dyes and phenols degradation
Comunicación presentanda al congreso EUROMAT2013, del 8 al 13 de Septiembre, Sevilla.There is increasing interest in using heterogeneous catalysis for mineralization of
organic pollutants. Within Advanced Oxidation Processes (AOPs), Photo-Fenton
reaction is one of the most efficient methodologies. To date, most of heterogeneous
iron catalysts studied was based on oxides or hydroxides. We extend here our previous
studies on phenol photodegradation [1] by exploring the photocatalytic activity of
various hybrid MII phosphonates (MII = Mn, Fe, Cu) for several organic pollutants.
Synthesis conditions, pre-activation, H2O2 concentration, and surface characteristic have
been studied/optimized. For dyes, decolouring and mineralization degrees up to 90%
and 45%, respectively, were attained. Chemical analysis and X-ray photoelectron
spectroscopy revealed the dynamic character of the photocatalyst surface upon reaction.MAT2010-15175; FQM-11
2D Corrugated Magnesium Carboxyphosphonate Materials: Topotactic Transformations and Interlayer “Decoration” with Ammonia
In this paper we report the synthesis and structural characterization of the 2D layered coordination polymer Mg(BPMGLY)(H2O)2 (BPMGLY = bis-phosphonomethylglycine, (HO3PCH2)2N(H)COO2−). The Mg ion is found in a slightly distorted octahedral environment formed by four phosphonate oxygens and two water molecules. The carboxylate group is deprotonated but noncoordinated. This compound is a useful starting material for a number of topotactic transformations. Upon heating at 140 °C one (of the two) Mg-coordinated water molecule is lost, with the archetype 2D structure maintaining itself. However, the octahedral Mg in Mg(BPMGLY)(H2O)2 is now converted to trigonal bipyramidal in Mg(BPMGLY)(H2O). Upon exposure of the monohydrate Mg(BPMGLY)(H2O) compound to ammonia, one molecule of ammonia is inserted into the interlayer space and stabilized by hydrogen bonding. The 2D layered structure of the product Mg(BPMGLY)(H2O)(NH3) is still maintained, with Mg now acquiring a pseudo-octahedral environment. All of these topotactic transformations are also accompanied by changes in hydrogen bonding between the layers.Proyecto nacional MAT2010-1517
Structural Mapping and Framework Interconversions in 1D, 2D, and 3D Divalent Metal R,S-Hydroxyphosphonoacetate Hybrids
Reactions of divalent cations (Mg2þ, Co2þ, Ni2þ, and Zn2þ) with R,S-hydroxyphosphonoacetic acid (HPAA) in aqueous solutions (pH values ranging 1.0-4.0) yielded a range of crystalline hydrated M-HPAA hybrids. Onedimensional (1D) chain compounds were formed at room temperature whereas reactions conducted under hydrothermal conditions resulted in two-dimensional (2D) layered frameworks or, in some cases, three-dimensional (3D) networks incorporating various alkaline cations. 1D phases with compositions [M{HO3PCH(OH)CO2}(H2O)2]· 2H2O (M = Mg, Co, and Zn) were isolated. These compounds were dehydrated in liquid water to yield the corresponding [M{HO3PCH(OH)CO2}(H2O)2] compounds lacking the lattice water between the 1D chains. [M{HO3PCH(OH)CO2}(H2O)2] (M = Mg, Ni, Co, Zn) compounds were formed by crystallization at room temperature
(at higher pH values) or also by partial dehydration of 1D compounds with higher hydration degrees. Complete dehydration of these 1D solids at 240-270 ºC led to 3D phases, [M{HO3PCH(OH)CO2}]. The 2D layered compound [Mg{HO3PCH(OH)CO2}(H2O)2] was obtained under hydrothermal conditions. For both synthesis methods, addition of alkali metal hydroxides to adjust the pH usually led to mixed phase materials, whereas direct reactions between the metal oxides and the hydroxyphosphonoacetic acid gave single phase materials. On the other hand, adjusting the pH with acetate salts and increasing the ratio M2þ/HPAA and/or the Aþ/M2þ ratio (A = Na, K) resulted in 3D networks, where the alkali cations were incorporated within the frameworks for charge compensation. The crystal structures of eight new M(II)-HPAA hybrids are reported herein and the thermal behavior related to dehydration/rehydration of some compounds are studied in detail.Proyecto nacional MAT2006-11080-C02-0
Structural Variability in Multifunctional Metal Xylenediaminetetraphosphonate Hybrids
The two cornerstones in the field of MOFs are the Secondary Building Units (SBU’s or “bricks”) and the organic linkers. The structural tunability of crystalline MOFs coupled, when possible, with high chemical and thermal robustness, makes them suitable materials to correlate structure with function [1]. Hence, the research focus has been set recently to the potential applications of some of these compounds, including phosphonate-based MOFs [2].
We report two families of isostructural divalent (Ca, Mg, Co, Zn) hybrid phosphonate MOFs based on the tetraphosphonate ligands 1,4- and 1,3-bis(aminomethyl)benzene-N,N’-bis(methylenephosphonic acid), (H2O3PCH2)2-N- CH2C6H4CH2-N(CH2PO3H2)2, (designated as p-C12H20O12N2P4•or m-C12H20O12N2P4, respectively). The use of these two functionalized ligands, otherwise chemically and structurally quite similar, represents a good example of how small stereochemical changes in the organic linker may dramatically affect structural features and dimensionality of the resulting solids and, hence, their final properties. The crystal structures of representative compounds of each family were solved ab initio from synchrotron powder diffraction data (λ=0.2998 Å, beamline ID31-ESRF) and were used as starting models for the Rietveld refinements of the remaining components. M-p-C12H20O12N2P4 (M = Mg, Co and Zn) present low dimensionality (1D) within a wide range of experimental conditions (figure 1). In contrast, solids containing the linker m-H8L, M-m-C12H20O12N2P4 (M = Mg, Ca and Zn) tend to acquire a 3D pillared open-framework for a wide range of metal ion sizes (figure 2). Two representative members, Mg-p-C12H20O12N2P4 and Zn-m-C12H20O12N2P4, were studied for characterizing their proton-conducting behavior. At 98 % RH and T = 297 K, σ are close to 9.4x10-5 Sxcm-1 for both compounds [3]. Their crystal structures, thermal stability and proton conductivity properties will be reported and discussed.Proyecto MAT2010-15175, grupo PAIDI FQM-11
In situ high pressure powder diffraction study of proton conductors based on metal phosphonates
Soft Porous Metal Organic frameworks (MOFs) are referred to as a class of coordination polymers that exhibit structural flexibility in response to guest interactions or physical stimuli [1]. By combining softness and regularity, the responsive crystalline frameworks show, for instance, unique mechanisms of separation and storage of gases.
Here we report the effects of high pressures of CO2 on the frameworks of two types of coordination polymers based on multifunctional metal phosphonates, which exhibit proton conductivity at high relative humidity in addition to porous properties. The first one, Ni2(H2O)2(O3PCH2N(C4H8)NCH2PO3)⋅8H2O (Ni-STA-12) is a well-known MOF material structural featured by 1D channels build from MO5N octahedra linked by the piperazinyl moieties [2]. The second solid, Mg[(HO3PCH2)2NHCH2C6H4CH2NH-(CH2PO3H)2]·2H2O, (MgHDTMP·2H2O), is a pillared layer metal phosphonate containing flexible alkyldiaminetetraphosphonate as linker of the inorganic layers. For both solids, in situ synchrotron powder diffraction data were collected on BL04-MSPD under different pressures of CO2 (up to ~10 bar) and temperatures at ALBA (Barcelona, Spain). The resulting structural changes observed on their frameworks as well as their proton conductivities will be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Junta de Andalucía,Proyecto de Excelencia P12-FQM-1656 MINECO: MAT2013-41836-R
Crystal engineering in confined spaces. A novel method to grow crystalline metal phosphonates in alginate gel systems
In this paper we report a crystal growth method for metal phosphonate frameworks in alginate gels. It consists of a metalcontaining alginate gel, in which a solution of phosphonate ligand is slowly diffused. Crystals of metal phosphonate products are formed inside the gel. We have applied this for a variety of metal ions (alkaline-earth metals, transition metals and lanthanides) and a number of polyphosphonic acid and mixed carboxy/phosphonic acid ligands.Proyecto nacional MAT2010-1517
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