The mechanism and intermediates in the UV-light-initiated ligand rearrangement of fac-Re(diimine)(CO)3Cl to form the mer isomer, when incorporated into a 3D metal–organic framework (MOF), have been ...investigated. The structure hosting the rhenium diimine complex is a 3D network with the formula {Mn(DMF)2LRe(CO)3Cl}∞ (ReMn; DMF = N,N-dimethylformamide), where the diimine ligand L, 2,2′-bipyridine-5,5′-dicarboxylate, acts as a strut of the MOF. The incorporation of ReMn into a KBr disk allows spatial distribution of the mer-isomer photoproduct in the disk to be mapped and spectroscopically characterized by both Fourier transform infrared and Raman microscopy. Photoisomerization has been monitored by IR spectroscopy and proceeds via dissociation of a CO to form more than one dicarbonyl intermediate. The dicarbonyl species are stable in the solid state at 200 K. The photodissociated CO ligand appears to be trapped within the crystal lattice and, upon warming above 200 K, readily recombines with the dicarbonyl intermediates to form both the fac-Re(diimine)(CO)3Cl starting material and the mer-Re(diimine)(CO)3Cl photoproduct. Experiments over a range of temperatures (265–285 K) allow estimates of the activation enthalpy of recombination for each process of ca. 16 (±6) kJ mol–1 (mer formation) and 23 (±4) kJ mol–1 (fac formation) within the MOF. We have compared the photochemistry of the ReMn MOF with a related alkane-soluble Re(dnb)(CO)3Cl complex (dnb = 4,4′-dinonyl-2,2′-bipyridine). Time-resolved IR measurements clearly show that, in an alkane solution, the photoinduced dicarbonyl species again recombines with CO to both re-form the fac-isomer starting material and form the mer-isomer photoproduct. Density functional theory calculations of the possible dicarbonyl species aids the assignment of the experimental data in that the ν(CO) IR bands of the CO loss intermediate are, as expected, shifted to lower energy when the metal is bound to DMF rather than to an alkane and both solution data and calculations suggest that the ν(CO) band positions in the photoproduced dicarbonyl intermediates of ReMn are consistent with DMF binding.
We present the magnetic properties of a new family of S = 1 molecule-based magnets, NiF2(3,5-lut)4·2H2O and NiX2(3,5-lut)4, where X = HF2, Cl, Br, or I (lut = lutidine C7H9N). Upon creation of ...isolated Ni–X···X–Ni and Ni–F–H–F···F–H–F–Ni chains separated by bulky and nonbridging lutidine ligands, the effect that halogen substitution has on the magnetic properties of transition-metal-ion complexes can be investigated directly and in isolation from competing processes such as Jahn–Teller distortions. We find that substitution of the larger halide ions turns on increasingly strong antiferromagnetic interactions between adjacent Ni2+ ions via a novel through-space two-halide exchange. In this process, the X···X bond lengths in the Br and I materials are more than double the van der Waals radius of X yet can still mediate significant magnetic interactions. We also find that a simple model based on elongation/compression of the Ni2+ octahedra cannot explain the observed single-ion anisotropy in mixed-ligand compounds. We offer an alternative that takes into account the difference in the electronegativity of axial and equatorial ligands.
Patients' trauma burdens are a combination of anatomic damage, physiologic derangement, and the resultant depletion of reserve. Typically, Injury Severity Score (ISS) >15 defines major anatomic ...injury and Revised Trauma Score (RTS) <7.84 defines major physiologic derangement, but there is no standard definition for reserve. The Need For Trauma Intervention (NFTI) identifies severely depleted reserves (NFTI+) with emergent interventions and/or early mortality. We hypothesized NFTI would have stronger associations with outcomes and better model fit than ISS and RTS.
Thirty-eight adult and pediatric U.S. trauma centers submitted data for 88,488 encounters. Mixed models tested ISS greater than 15, RTS less than 7.84, and NFTI's associations with complications, survivors' discharge to continuing care, and survivors' length of stay (LOS).
The NFTI had stronger associations with complications and LOS than ISS and RTS (odds ratios 99.5% confidence interval: NFTI = 9.44 8.46-10.53; ISS = 5.94 5.36-6.60, RTS = 4.79 4.29-5.34; LOS incidence rate ratios (99.5% confidence interval): NFTI = 3.15 3.08-3.22, ISS = 2.87 2.80-2.94, RTS = 2.37 2.30-2.45). NFTI was more strongly associated with continuing care discharge but not significantly more than ISS (relative risk 99.5% confidence interval: NFTI = 2.59 2.52-2.66, ISS = 2.51 2.44-2.59, RTS = 2.37 2.28-2.46). Cross-validation revealed that in all cases NFTI's model provided a much better fit than ISS greater than 15 or RTS less than 7.84.
In this multicenter study, NFTI had better model fit and stronger associations with the outcomes than ISS and RTS. By determining depletion of reserve via resource consumption, NFTI+ may be a better definition of major trauma than the standard definitions of ISS greater than 15 and RTS less than 7.84. Using NFTI may improve retrospective triage monitoring and statistical risk adjustments.
Prognostic, level IV.
We present the magnetic properties of a new family of
= 1 molecule-based magnets, NiF
(3,5-lut)
·2H
O and NiX
(3,5-lut)
, where X = HF
, Cl, Br, or I (lut = lutidine C
H
N). Upon creation of isolated ...Ni-X···X-Ni and Ni-F-H-F···F-H-F-Ni chains separated by bulky and nonbridging lutidine ligands, the effect that halogen substitution has on the magnetic properties of transition-metal-ion complexes can be investigated directly and in isolation from competing processes such as Jahn-Teller distortions. We find that substitution of the larger halide ions turns on increasingly strong antiferromagnetic interactions between adjacent Ni
ions via a novel through-space two-halide exchange. In this process, the X···X bond lengths in the Br and I materials are more than double the van der Waals radius of X yet can still mediate significant magnetic interactions. We also find that a simple model based on elongation/compression of the Ni
octahedra cannot explain the observed single-ion anisotropy in mixed-ligand compounds. We offer an alternative that takes into account the difference in the electronegativity of axial and equatorial ligands.
By design, targeted pseudo-octahedral Ni(II) complexes composed of simple ligands L show easy-plane anisotropy with 8 ≤ D ≤ 25 K. For small donor-atoms; e.g., N, F, and O, D is the largest for NiN4F2 ...and smallest for NiN4O2. This correlates with Ni-Lax ≤ Ni-Neq and the ligand spectro-chemical properties.
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We examine the crystal structures and magnetic properties of several S = 1 Ni(II) coordination compounds, molecules and polymers, that include the bridging ligands HF2−, AF62− (A = Ti, Zr) and pyrazine or non-bridging ligands F−, SiF62−, glycine, H2O, 1-vinylimidazole, 4-methylpyrazole and 3-hydroxypyridine. Pseudo-octahedral NiN4F2, NiN4O2 or NiN4OF cores consist of equatorial Ni-N bonds that are equal to or slightly longer than the axial Ni-Lax bonds. By design, the zero-field splitting (D) is large in these systems and, in the presence of substantial exchange interactions (J), can be difficult to discriminate from magnetometry measurements on powder samples. Thus, we relied on pulsed-field magnetization in those cases and employed electron-spin resonance (ESR) to confirm D when J ≪ D. The anisotropy of each compound was found to be easy-plane (D > 0) and range from ≈ 8–25 K. This work reveals a linear correlation between the ratio d(Ni-Lax)/d(Ni-Neq) and D although the ligand spectrochemical properties may play an important role. We assert that this relationship allows us to predict the type of magnetocrystalline anisotropy in tailored Ni(II) quantum magnets.
The Cribari Matrix Method (CMM) is the current standard to identify over/undertriage but requires manual trauma triage reviews to address its inadequacies. The Standardized Triage Assessment Tool ...(STAT) partially emulates triage review by combining CMM with the Need For Trauma Intervention, an indicator of major trauma. This study aimed to validate STAT in a multicenter sample.
Thirty-eight adult and pediatric US trauma centers submitted data for 97,282 encounters. Mixed models estimated the effects of overtriage and undertriage versus appropriate triage on the odds of complication, odds of discharge to a continuing care facility, and differences in length of stay for both CMM and STAT. Significance was assessed at p <0.005.
Overtriage (53.49% vs. 30.79%) and undertriage (17.19% vs. 3.55%) rates were notably lower with STAT than with CMM. CMM and STAT had significant associations with all outcomes, with overtriages demonstrating lower injury burdens and undertriages showing higher injury burdens than appropriately triaged patients. STAT indicated significantly stronger associations with outcomes than CMM, except in odds of discharge to continuing care facility among patients who received a full trauma team activation where STAT and CMM were similar.
This multicenter study strongly indicates STAT safely and accurately flags fewer cases for triage reviews, thereby reducing the subjectivity introduced by manual triage determinations. This may enable better refinement of activation criteria and reduced workload.
Near-ideal molecule-based Haldane spin chain Williams, Robert C.; Blackmore, William J. A.; Curley, Samuel P. M. ...
Physical review research,
01/2020, Letnik:
2, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The molecular coordination complex NiI_{2}(3,5-lut)_{4} where (3,5-lut) = (3,5-lutidine) =(C_{7}H_{9}N) has been synthesized and characterized by several techniques including synchrotron x-ray ...diffraction, electron-spin resonance, superconducting quantum interference device magnetometry, pulsed-field magnetization, inelastic neutron scattering, and muon spin relaxation. Templated by the configuration of 3,5-lut ligands the molecules pack in-registry with the Ni–I⋯I–Ni chains aligned along the c axis. This arrangement leads to an uncommon through-space I⋯I magnetic coupling which is directly measured in this work. The net result is a near-ideal realization of the S=1 Haldane chain with J=17.5K and energy gaps of Δ^{∥}=5.3K Δ^{⊥}=7.7K, split by the easy-axis single-ion anisotropy D=−1.2K. The ratio D/J=−0.07 affords one of the most isotropic Haldane systems yet discovered, while the ratio Δ_{0}/J=0.40(1) (where Δ_{0} is the average gap size) is close to its ideal theoretical value, suggesting a very high degree of magnetic isolation of the spin chains in this material. The Haldane gap is closed by orientation-dependent critical fields μ_{0}H_{c}^{∥}=5.3T and μ_{0}H_{c}^{⊥}=4.3T, which are readily accessible experimentally and permit investigations across the entirety of the Haldane phase, with the fully polarized state occurring at μ_{0}H_{s}^{∥}=46.0T and μ_{0}H_{s}^{⊥}=50.7T. The results are explicable within the so-called fermion model, in contrast to other reported easy-axis Haldane systems. Zero-field magnetic order is absent down to 20mK and emergent end-chain effects are observed in the gapped state, as evidenced by detailed low-temperature measurements.
Objectives
Estimates of depression prevalence in pregnancy and postpartum are based on the Edinburgh Postnatal Depression Scale (EPDS) more than on any other method. We aimed to determine if any EPDS ...cutoff can accurately and consistently estimate depression prevalence in individual studies.
Methods
We analyzed datasets that compared EPDS scores to Structured Clinical Interview for DSM (SCID) major depression status. Random‐effects meta‐analysis was used to compare prevalence with EPDS cutoffs versus the SCID.
Results
Seven thousand three hundred and fifteen participants (1017 SCID major depression) from 29 primary studies were included. For EPDS cutoffs used to estimate prevalence in recent studies (≥9 to ≥14), pooled prevalence estimates ranged from 27.8% (95% CI: 22.0%–34.5%) for EPDS ≥ 9 to 9.0% (95% CI: 6.8%–11.9%) for EPDS ≥ 14; pooled SCID major depression prevalence was 9.0% (95% CI: 6.5%–12.3%). EPDS ≥14 provided pooled prevalence closest to SCID‐based prevalence but differed from SCID prevalence in individual studies by a mean absolute difference of 5.1% (95% prediction interval: −13.7%, 12.3%).
Conclusion
EPDS ≥14 approximated SCID‐based prevalence overall, but considerable heterogeneity in individual studies is a barrier to using it for prevalence estimation.
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