Magnetic properties and magnetocaloric effect of Ln = Dy, Tb carborane-based metal-organic frameworks.

We present the synthesis and magneto-thermal properties of carborane-based lanthanide metal-organic frameworks (MOFs) with the formula {[(Ln)3(mCB-L)4(NO3)(DMF)n]·Solv}, where Ln = Dy or Tb, characterized by dc and ac susceptibility, X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD) and heat capacity measurements. The MOF structure is formed by polymeric 1D chains of Ln ions with three different coordination environments (Ln1, Ln2, Ln3) running along the b-axis, linked by carborane-based linkers thus to provide a 3D structure. Static magnetic measurements reveal that these MOFs behave at low temperature as a system of S* = 1/2 Ising spins, weakly interacting ferromagnetically along the 1D polymeric chain (J*/kB = +0.45 K (+0.5 K) interaction constant estimated for Dy-MOF (Tb-MOF)) and coupled to Ln ions in adjacent chains through dipolar antiferromagnetic interactions. The Dy MOF exhibits slow relaxation of magnetization through a thermally activated process, transitioning to quantum tunneling of the magnetization at low temperatures, while both compounds exhibit field-induced relaxation through a very slow, direct process. The maximum magnetic entropy changes (-ΔSmaxm) for an applied magnetic field change of 2-0 T are 5.71 J kg-1 K-1 and 4.78 J kg-1 K-1, for Dy and Tb MOFs, respectively, while the magnetocaloric effect (MCE) peak for both occurs at T ∼ 1.6 K, approximately double that for the Gd counterpart.

Extracting mycotoxins from edible vegetable oils by using green, ecofriendly deep eutectic solvents.

In this work, we developed an environmentally friendly liquid-liquid microextraction method using a natural deep eutectic solvent in combination with liquid chromatography for the simultaneous determination of four mycotoxins (deoxynivalenol, alternariol, ochratoxin A and zearalenone) in edible vegetable oils. A chemometric approach assessed the effect of the operational parameters on the mycotoxin extraction efficiency. The extracts were analyzed by HPLC coupled with a diode array and fluorescence detector. The optimum NADES composition resulted in the highest extraction recoveries, and it was applied to coextract the target mycotoxins in several types of edible vegetable oils without using hazardous solvents or requiring further clean-up. The limits of detection ranged from 0.07 to 300 µg kg-1, and recoveries were close to 100%, except for zearalenone (viz. 35%), with relative standard deviations below 9% in all cases. The proposed method was validated following the European Commission 2002/657/EC and 2006/401/EC.

Origin of the Unusual Ground-State Spin S = 9 in a Cr10 Single-Molecule Magnet.

The molecular wheel [Cr10(OMe)20(O2CCMe3)10], abbreviated {Cr10}, with an unusual intermediate total spin S = 9 and non-negligible cluster anisotropy, D/kB = -0.045(2) K, is a rare case among wheels based on an even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state (S = 0). Herein, we unveil the origin of such a behavior. Angular magnetometry measurements performed on a single crystal confirmed the axial anisotropic behavior of {Cr10}. For powder samples, the temperature dependence of the susceptibility plotted as χT(T) showed an overall ferromagnetic (FM) behavior down to 1.8 K, whereas the magnetization curve M(H) did not saturate at the expected 30 µB/fu for 10 FM coupled 3/2 spin Cr3+ ions, but to a much lower value, corresponding to S = 9. In addition, the X-ray magnetic circular dichroism (XMCD) measured at high magnetic field (170 kOe) and 7.5 K showed the polarization of the cluster moment up to 23 µB/fu. The magnetic results can be rationalized within a model, including the cluster anisotropy, in which the {Cr10} wheel is formed by two semiwheels, each with four Cr3+ spins FM coupled (JFM/kB = 2.0 K), separated by two Cr3+ ions AF coupled asymmetrically (J23/kB = J78/kB = -2.0 K; J34/kB = J89/kB = -0.25 K). Inelastic neutron scattering and heat capacity allowed us to confirm this model leading to the S = 9 ground state and first excited S = 8. Single-molecule magnet behavior with an activation energy of U/kB = 4.0(5) K in the absence of applied field was observed through ac susceptibility measurements down to 0.1 K. The intriguing magnetic behavior of {Cr10} arises from the detailed asymmetry in the molecule interactions produced by small-angle distortions in the angles of the Cr-O-Cr alkoxy bridges coupling the Cr3+ ions, as demonstrated by ab initio and density functional theory calculations, while the cluster anisotropy can be correlated to the single-ion anisotropies calculated for each Cr3+ ion in the wheel.

Multicriteria Decision Analysis for Updating of Quality Indicators for Inflammatory Bowel Disease Comprehensive Care Units in Spain.

BACKGROUND AND AIMS: Management of inflammatory bowel disease [IBD] is complex and IBD Comprehensive Care Units [ICCUs] facilitate the delivery of quality care to IBD patients. The objective of this study was to update the existing set of quality indicators [QIs] for ICCUs, based on a nationwide quality certification programme carried out in Spain, from a multi-stakeholder perspective and using multicriteria decision analysis [MCDA] methodology. METHODS: An MCDA comprising three different phases was conducted. In phase 1, a systematic literature review was performed, and after validation by a scientific committee comprising 11 experts, a preliminary set of QIs was developed. In phase 2, a larger group of 49 experts determined the relevance and relative importance of each QI by prioritising and weighing the preliminary set. Finally in phase 3, the scientific committee reviewed the results and made a final selection via a deliberative process. RESULTS: The final set comprised 67 QIs, classified as Structure [23 QIs], Process [35 QIs] and Outcome [9 QIs], which were ranked according to their relative importance. Multidisciplinary management was the most important requirement in ICCUs, followed by continuity of care, standardisation of clinical care and, especially, the incorporation of patients' reported outcomes. CONCLUSIONS: This updated set of QIs comprises a weighted and prioritised set of items that represent the essential minimum of criteria for ensuring appropriate quality of care in the management of IBD patients.

Luminescent and Magnetic Tb-MOF Flakes Deposited on Silicon.

The synthesis of a terbium-based 2D metal-organic framework (MOF), of formula [Tb(MeCOO)(PhCOO)2] (1), a crystalline material formed by neutral nanosheets held together by Van der Waals interactions, is presented. The material can be easily exfoliated by sonication and deposited onto different substrates. Uniform distributions of Tb-2D MOF flakes onto silicon were obtained by spin-coating. We report the luminescent and magnetic properties of the deposited flakes compared with those of the bulk. Complex 1 is luminescent in the visible and has a sizeable quantum yield of QY = 61% upon excitation at 280 nm. Photoluminescence measurements performed using a micro-Raman set up allowed us to characterize the luminescent spectra of individual flakes on silicon. Magnetization measurements of flakes-on-silicon with the applied magnetic field in-plane and out-of-plane display anisotropy. Ac susceptibility measurements show that 1 in bulk exhibits field-induced slow relaxation of the magnetization through two relaxation paths and the slowest one, with a relaxation time of τlf ≈ 0.5 s, is assigned to a direct process mechanism. The reported exfoliation of lanthanide 2D-MOFs onto substrates is an attractive approach for the development of multifunctional materials and devices for different applications.

Slow Magnetic Relaxation in {[CoCxAPy)] 2.15 H2O}n MOF Built from Ladder-Structured 2D Layers with Dimeric SMM Rungs.

We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 H2O}n (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4,4`-azopyridine) (1) that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the bc plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer rungs, running parallel to the c-axis. The crystal packing of 2D layers shows the presence of infinite channels running along the c crystallographic axis, which accommodate the disordered solvate molecules. The Co(II) is six-coordinated in a distorted octahedral geometry, where the equatorial plane is occupied by four carboxylate oxygen atoms. Two nitrogen atoms from APy ligands are coordinated in apical positions. The single-ion magnetic anisotropy has been determined by low temperature EPR and magnetization measurements on an isostructural compound {[Zn0.8Co0.2CxAPy]·1.5 CH3OH}n (2). The results show that the Co(II) ion has orthorhombic anisotropy with the hard-axis direction in the C2V main axis, lying the easy axis in the distorted octahedron equatorial plane, as predicted by the ab initio calculations of the g-tensor. Magnetic and heat capacity properties at very low temperatures are rationalized within a S* = 1/2 magnetic dimer model with anisotropic antiferromagnetic interaction. The magnetic dimer exhibits slow relaxation of the magnetization (SMM) below 6 K in applied field, with a tlf ≈ 2 s direct process at low frequencies, and an Orbach process at higher frequencies with U/kB = 6.7 ± 0.5 K. This compound represents a singular SMM MOF built-up of Co-dimers with an anisotropic exchange interaction.

A Multifunctional Dysprosium-Carboxylato 2D Metall-Organic Framework.

We report the microwave assisted synthesis of a bidimensional (2D) MOF of formula [Dy(MeCOO)(PhCOO)2 ]n (1) and its magnetically diluted analogue [La0.9 Dy0.1 (MeCOO)(PhCOO)2 ] (1 d). 1 is a 2D material with single-ion-magnet (SIM) behaviour and 1 d is a multifunctional, magnetic and luminescent 2D material. 1 can be exfoliated into stable nanosheets by sonication.

A Randomized Clinical Trial on the Use of Antiseptic Solutions for the Pin-Site Care of External Fixators: Chlorhexidine-Alcohol Versus Povidone-Iodine.

Pin-site infections remain a common clinical complication in patients with external fixators. Pin-site care is commonly performed with either chlorhexidine-alcohol solution or povidone-iodine solution. This study aimed to investigate the superiority of chlorhexidine-alcohol solution versus povidone-iodine solution for external fixator pin-site care in pin-site infection. This prospective randomized clinical trial using an open, parallel-group design was conducted in a single Spanish hospital. Eligible consenting patients from November 2018 to May 2019 who underwent placement of an external fixator were included. Patients were randomly assigned to receive pin-site care using either a 2% chlorhexidine-alcohol solution or a 10% povidone-iodine solution. The primary endpoint was the development of a pin-site infection. In total, 568 pins were analyzed (128 patients, with a mean of 4.3 pins per patient). No significant differences were found between groups. However, statistically significant differences were found regarding time and infection variables. The longer the person had the fixator, the higher the risk of infection, t(x) = 5.49, p = .002. Both chlorhexidine-alcohol and povidone-iodine solutions are equally effective antiseptic agents for the prevention of infections in external fixators.

Correction: Magnetic properties of the seven-coordinated nanoporous framework material Co(bpy)1.5(NO3)2 (bpy = 4,4'-bipyridine).

Correction for 'Magnetic properties of the seven-coordinated nanoporous framework material Co(bpy)1.5(NO3)2 (bpy = 4,4'-bipyridine)' by Elena Bartolomé et al., Dalton Trans., 2012, 41, 10382-10389.

Chemical tunnel-splitting-engineering in a dysprosium-based molecular nanomagnet.

Total control over the electronic spin relaxation in molecular nanomagnets is the ultimate goal in the design of new molecules with evermore realizable applications in spin-based devices. For single-ion lanthanide systems, with strong spin-orbit coupling, the potential applications are linked to the energetic structure of the crystal field levels and quantum tunneling within the ground state. Structural engineering of the timescale of these tunneling events via appropriate design of crystal fields represents a fundamental challenge for the synthetic chemist, since tunnel splittings are expected to be suppressed by crystal field environments with sufficiently high-order symmetry. Here, we report the long missing study of the effect of a non-linear (C4) to pseudo-linear (D4d) change in crystal field symmetry in an otherwise chemically unaltered dysprosium complex. From a purely experimental study of crystal field levels and electronic spin dynamics at milliKelvin temperatures, we demonstrate the ensuing threefold reduction of the tunnel splitting.

Assessment of the Pneumatic Ischemia Technique Using the Limb Occlusion Pressure During Upper Limb Surgery.

PURPOSE: The purpose of our study was to evaluate effective ischemia and its associated complications using the limb occlusion pressure technique versus standard pneumatic ischemia technique. DESIGN: Single-centered randomized, controlled clinical trial. METHODS: One hundred sixty participants were randomized into two equal and parallel groups: (1) intervention group-LOP technique, and (2) control group-standard pneumatic ischemia technique. FINDINGS: Anesthetic incidences (need to administer analgesics for pain and/or hypnotics for anxiety) were similar in both groups. Statistically significant differences were observed for pain, hyperemia, and hospitalization, with higher values in the control group. Patients in the intervention group had, at 95% confidence, a 2.9 times greater chance of having optimal ischemia (assessed as 9 on the analog scale) than patients in the control group (odds ratio, 2.9; 95% confidence interval, 1.4 to 6.1). CONCLUSIONS: Intervention group patients had lower indexes of hyperemia, pain, and hospital stay.

Variables to Predict Mortality in Hip Fractures in Patients Over 65 Years of Age: A Study on the Role of Anticoagulation as a Risk Factor.

The objective of this research was to study the possible relationship between the consumption of dicoumarinic agents (understanding the consumption of acenocoumarol as regulated and monitored anticoagulation) and the mortality rate in people older than 65 years undergoing a hip fracture (HF) intervention. It was a retrospective, observational and descriptive study. Nine hundred fifty-seven patients were included who underwent an intervention for HF between the years 2012 and 2014 in a third-level hospital. Patients took acenocoumarol (16.1%), which compared with nonanticoagulated patients took longer in receiving intervention, they remained hospitalized for more days, and they presented greater mortality within the first year after the intervention. Likewise, those who presented greater risk according to the classification system used by the American Society of Anesthesiologists (ASA) to estimate the risk of anesthesia for the different states of the patients who were anticoagulated also suffered greater mortality. The next factors increased the mortality in the first year: advanced age, delayed surgery, male sex, need for transfusion, high international normalized ratio, consumption of acenocoumarol, and a high ASA risk. We concluded the consumption of acenocoumarol increased the risk of mortality within the first year after surgery in 1.3 of possible cases. Other risk factors that also independently increased the risk of mortality included advanced age, male sex, delayed surgery, the need for transfusions, and surgical risk (for high levels in the ASA classification).

Slow magnetic relaxation in a dimeric Mn2Ca2 complex enabled by the large Mn(iii) rhombicity.

In this paper we present the characterization of a complex with the formula [Mn2Ca2(hmp)6(H2O)4(CH3CN)2](ClO4)4 (1), where hmp-H = 2-(hydroxymethyl)pyridine. Compound 1 crystallizes in the monoclinic space group C2/c with the cation lying on an inversion centre. Static magnetic susceptibility, magnetization and heat capacity measurements reflect a unique Mn(iii) valence state, and single-ion ligand field parameters with remarkable large rhombic distortion (D/kB = -6.4 K, E/kB = -2.1 K), in good agreement with the high-field electron paramagnetic resonance experiments. At low temperature Mn2Ca2 cluster behaves as a system of ferromagnetically coupled (J/kB = 1.1 K) Mn dimers with a ST = 4 and mT = ±4 ground state doublet. Frequency dependent ac susceptibility measurements reveal the slow magnetic relaxation characteristic of a single molecule magnet (SMM) below T = 4 K. At zero magnetic field, an Orbach-type spin relaxation process (τ ∼ 10-5 s) with an activation energy Ea = 5.6 K is observed, enabled by the large E/D rhombicity of the Mn(iii) ions. Upon the application of a magnetic field, a second, very slow process (τ ∼ 0.2 s) is observed, attributed to a direct relaxation mechanism with enhanced relaxation time owing to the phonon bottleneck effect.

Emerging Diluted Ferromagnetism in High-Tc Superconductors Driven by Point Defect Clusters.

Defects in ceramic materials are generally seen as detrimental to their functionality and applicability. Yet, in some complex oxides, defects present an opportunity to enhance some of their properties or even lead to the discovery of exciting physics, particularly in the presence of strong correlations. A paradigmatic case is the high-temperature superconductor YBa2Cu3O7-δ (Y123), in which nanoscale defects play an important role as they can immobilize quantized magnetic flux vortices. Here previously unforeseen point defects buried in Y123 thin films that lead to the formation of ferromagnetic clusters embedded within the superconductor are unveiled. Aberration-corrected scanning transmission microscopy has been used for exploring, on a single unit-cell level, the structure and chemistry resulting from these complex point defects, along with density functional theory calculations, for providing new insights about their nature including an unexpected defect-driven ferromagnetism, and X-ray magnetic circular dichroism for bearing evidence of Cu magnetic moments that align ferromagnetically even below the superconducting critical temperature to form a dilute system of magnetic clusters associated with the point defects.

Prevalencia de úlceras por presión en pacientes sometidos a artrodesis de columna / Prevalence of pressure ulcers in patients undergoing an arthrodesis spine

Objetivos: Identificar la incidencia de úlceras por presión (UPP) en el quirófano en pacientes sometidos a artrodesis de columna realizadas en el intervalo de 2 años. Material y métodos: Diseño descriptivo, trasversal retrospectivo. Revisión de historias clínicas. Resultados: Se valoraron 269 pacientes, 52% mujeres, de una media de edad de 58,7 años. Las posiciones más frecuentes fueron decúbito supino y decúbito prono (34% ambas). La prevalencia de UPP fue del 14%, con un 51,4% de grado II, y la localización más frecuente fue tórax y frente. La mayor frecuencia de aparición fue a partir de las 4 horas de intervención, pero no hallamos relaciones significativas entre la aparición de úlceras por presión y otras variables. Conclusiones: Es necesario llevar a cabo estudios de intervención para prevenir UPP en el área quirúrgica, debido a que existe poca bibliografía al respecto. Por otro lado, la alta incidencia hallada nos hace plantearnos la necesidad de aumentar las medidas preventivas por parte de enfermería

Objectives: Identify the incidence of pressure ulcers (PU) in surgery in patients undergoing spinal fusion performed in the range of 2 years. Material and methods: Descriptive, transversal and retrospective design. Review of medical histories. Results: 269 patients were evaluated, 52% were women and the average age of 58.7 years. The most frequent were supine and prone positions (34% both). PU prevalence was 14%, with 51.4% grade II, the most frequent location was chest and forehead. The highest frequency of occurrence was from 4 hours intervention, but we have not significant relationships between pressure ulcers and other variables. Conclusions: It is necessary to carry out intervention studies to prevent PU in the surgical area, because there is little literature. On the other hand the high incidence found begs the need to increase preventive measures by nurses

{Dy(α-fur)3}n: from double relaxation single-ion magnet behavior to 3D ordering.

The synthesis and magnetostructural properties of a new low-dimensional magnetic system based on α-furoate ligands, {[Dy(α-C4H3OCOO)(µ-(α-C4H3OCOO))2(H2O)3]}n, abbreviated {Dy(α-fur)3}n, are reported. X-ray diffraction experiments results evidence the presence of two different Dy coordination environment types differing only in the position of one of the furoate ligands. The crystallographic structure is formed by polymeric chains along the c-axis, each composed of just one Dy type, coupled within the bc-plane with chains of the same Dy type. These planes, each of them containing only one Dy type, are randomly stacked along the a-axis. The magnetic behaviour was studied by magnetization, static and dynamic susceptibility, heat capacity measurements and ab initio simulations. The directions of the easy axes of magnetization, gyromagnetic values and energy level structures of the two Dy types were obtained from ab initio calculations. {Dy(α-fur)3}n exhibits slow magnetic relaxation dynamics below 10 K. The two Dy types with different coordination environments behave as single-ion magnets, with different thermal activation energies of 80.5(6) K and 32.4(5) K, until they reach, upon cooling, a quantum tunneling (QT) regime. Magnetic diluted samples, substituting Dy by Y, {Y(x)Dy(1-x)(α-fur)3}n, were prepared to study the effect of intercluster interactions. Decreasing the Dy interaction by dilution by 90-95% leaves the activation energy unchanged, but shifts the transition to the QT regime to lower temperatures. At T = 2.4 K the tunneling time constant has been shown to decrease weakly with the field in the x = 0 case, and more strongly for x = 0.9. As the external field increases, quantum tunneling is quenched and a new slow relaxation appears that is identified at high fields as caused by a direct relaxation process. As the temperature is decreased, interchain AF coupling becomes effective and gives rise to the occurrence of an antiferromagnetic 3D order transition at T(N) = 0.66 K. From all the evidence, it is concluded that within each bc-plane Dy ions arrange in chains along the c-direction, having weak uncompensated ferromagnetic spin-canted intrachain coupling and antiferromagnetic interchain coupling.

Magnetic properties of the seven-coordinated nanoporous framework material Co(bpy)1.5(NO3)2 (bpy = 4,4'-bipyridine).

The magnetic properties of the porous metal-organic complex Co(bpy)(1.5)(NO(3))(2) (bpy = 4,4'-bipyridine), investigated by SQUID magnetometry, EPR and heat capacity measurements, are reported. The tongue-and-groove structure of this complex is formed by the assembly of T-shaped building blocks, where each Co is bound to three bpy ligands. Co(II) is hepta-coordinated by three N atoms from the bpy units, and four O atoms from two nitrate groups. Experimental results showed a large crystal field effect induced anisotropy with a zero field splitting of Δ = 198 K between the ground and excited Kramers doublets, a factor of two larger than previously reported values in Co(II) hepta-coordinated complexes. EPR revealed orthorhombic crystal field anisotropy, with gyromagnetic principal values of g(1)* = 6.1, g(2)* = 4.2 and g(3)* = 2.2, in an S* = 1/2 effective spin on the ground state Kramers doublet. Ab initio simulations allowed us to assign the anisotropy easy axis of magnetization to the binary symmetry axis of the molecule, aligned with the Co-N apical direction of the T-block.