Trapping an Elusive Fe(IV)-Superoxo Intermediate Inside a Self-Assembled Nanocage in Water at Room Temperature.

Molecular cavities that mimic natural metalloenzymes have shown the potential to trap elusive reaction intermediates. Here, we demonstrate the formation of a rare yet stable Fe(IV)-superoxo intermediate at room temperature subsequent to dioxygen binding at the Fe(III) site of a (Et4N)2[FeIII(Cl)(bTAML)] complex confined inside the hydrophobic interior of a water-soluble Pd6L412+ nanocage. Using a combination of electron paramagnetic resonance, Mössbauer, Raman/IR vibrational, X-ray absorption, and emission spectroscopies, we demonstrate that the cage-encapsulated complex has a Fe(IV) oxidation state characterized by a stable S = 1/2 spin state and a short Fe-O bond distance of ∼1.70 Å. We find that the O2 reaction in confinement is reversible, while the formed Fe(IV)-superoxo complex readily reacts when presented with substrates having weak C-H bonds, highlighting the lability of the O-O bond. We envision that such optimally trapped high-valent superoxos can show new classes of reactivities catalyzing both oxygen atom transfer and C-H bond activation reactions.

Comparison of MAF-32 and a One-Pot Synthesized Superparamagnetic Iron Oxide/MAF-32 Composite for the Adsorption of Diclofenac.

The global presence of pharmaceutical pollutants in water sources represents a burgeoning public health concern. Recent studies underscore the urgency of addressing this class of emerging contaminants. In this context, our work focuses on synthesizing a composite material, FexOy/MAF-32, through a streamlined one-pot reaction process, as an adsorbent for diclofenac, an emerging environmental contaminant frequently found in freshwater environments and linked to potential toxicity towards several organisms such as fish and mussels. A thorough characterization was performed to elucidate the structural composition of the composite. The material presents magnetic properties attributed to its superparamagnetic behavior, which facilitates the recovery efficiency of the composite post-diclofenac adsorption. Our study further involves a comparative analysis between the FexOy/MAF-32 and a non-magnetic counterpart, comprised solely of 2-ethylimidazolate zinc polymer. This comparison aims to discern the relative advantages and disadvantages of incorporating magnetic iron oxide nanoparticles in the contaminant removal process facilitated by a coordination polymer. Our findings reveal that even a minimal incorporation of iron oxide nanoparticles substantially enhanced the composite's overall performance in pollutant adsorption.

Functional Model of Compound II of Cytochrome P450: Spectroscopic Characterization and Reactivity Studies of a FeIV-OH Complex.

Herein, we show that the reaction of a mononuclear FeIII(OH) complex (1) with N-tosyliminobenzyliodinane (PhINTs) resulted in the formation of a FeIV(OH) species (3). The obtained complex 3 was characterized by an array of spectroscopic techniques and represented a rare example of a synthetic FeIV(OH) complex. The reaction of 1 with the one-electron oxidizing agent was reported to form a ligand-oxidized FeIII(OH) complex (2). 3 revealed a one-electron reduction potential of -0.22 V vs Fc+/Fc at -15 °C, which was 150 mV anodically shifted than 2 (Ered = -0.37 V vs Fc+/Fc at -15 °C), inferring 3 to be more oxidizing than 2. 3 reacted spontaneously with (4-OMe-C6H4)3C• to form (4-OMe-C6H4)3C(OH) through rebound of the OH group and displayed significantly faster reactivity than 2. Further, activation of the hydrocarbon C-H and the phenolic O-H bond by 2 and 3 was compared and showed that 3 is a stronger oxidant than 2. A detailed kinetic study established the occurrence of a concerted proton-electron transfer/hydrogen atom transfer reaction of 3. Studying one-electron reduction of 2 and 3 using decamethylferrocene (Fc*) revealed a higher ket of 3 than 2. The study established that the primary coordination sphere around Fe and the redox state of the metal center is very crucial in controlling the reactivity of high-valent Fe-OH complexes. Further, a FeIII(OMe) complex (4) was synthesized and thoroughly characterized, including X-ray structure determination. The reaction of 4 with PhINTs resulted in the formation of a FeIV(OMe) species (5), revealing the presence of two FeIV species with isomer shifts of -0.11 mm/s and = 0.17 mm/s in the Mössbauer spectrum and showed FeIV/FeIII potential at -0.36 V vs Fc+/Fc couple in acetonitrile at -15 °C. The reactivity studies of 5 were investigated and compared with the FeIV(OH) complex (3).

Reoperation After Operative Treatment of Open Finger Fractures.

BACKGROUND: Our primary aim was to develop a prediction model for return to the operating room (OR) after open finger fractures by studying the reoperation rate of open finger fractures based on patient demographics, injury mechanism, injury severity, and type of initial surgical fixation. The secondary aim was to study the predictors for secondary surgery due to nonunion, postoperative infection, and secondary amputation. METHODS: In the retrospective chart review, 1321 open finger fractures of 907 patients were included. Demographic-, injury-, and treatment-related factors were gathered from medical records. RESULTS: We found that open fractures involving the thumb had lower odds of undergoing secondary surgery. Crush injury, proximal phalangeal fracture, arterial injury, other injured fingers, and other injuries to the ipsilateral hand were associated with higher odds of undergoing secondary surgery. However, the associated factors we identified were not powerful enough to create a predictive model. Other injury to the ipsilateral hand, vein repair, and external fixator as initial treatment were associated with postoperative nonunion. Crush injury and proximal phalangeal fracture were associated with postoperative infection. No factors were associated with secondary amputation. CONCLUSIONS: A quarter of open finger fractures will likely need more than one surgical procedure, especially in more severely injured fingers, due to crush or with vascular impairment. Furthermore, fractures involving the thumb have less reoperation, while fractures involving the proximal phalanx have poorest outcomes.

A Threshold QuickDASH Score for Estimating a Diagnosis of Major Depression in Patients With Fingertip Injuries in the American and Dutch Population.

BACKGROUND: The aim was to determine the threshold Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score that estimates a diagnosis of major depression in patients with fingertip injuries in American and Dutch patients. METHODS: In this observational cross-sectional study, 112 patients with a recent fingertip injury measured symptoms of depression with the Patient Health Questionnaire and upper extremity disability with the QuickDASH. RESULTS: In the US cohort, 8 of 56 patients had an estimated diagnosis of major depression. A threshold value of QuickDASH of 50 showed a sensitivity of 88% and a specificity of 81%, with a negative predicting value (NPV) of 95% for an estimated diagnosis of major depression. In the Dutch cohort, 7 of 56 patients had an estimated diagnosis of major depression. The same threshold score of 50 had a sensitivity of 71%, a specificity of 63%, and an NPV of 94%. CONCLUSIONS: We have found a correlation between experienced loss of function and an estimated diagnosis of major depression in patients with a fingertip injury. Referral to the primary care physician for further evaluation of depression in these patients is advised.

Self-assembly of iron oxide precursor micelles driven by magnetic stirring time in sol-gel coatings.

The purpose of this work is to fabricate self-assembled microstructures by the sol-gel method and study the morphological, structural and compositional dependence of ε-Fe2O3 nanoparticles embedded in silica when glycerol (GLY) and cetyl-trimethylammonium bromide (CTAB) are added as steric agents simultaneously. The combined action of a polyalcohol and a surfactant significantly modifies the morphology of the sample giving rise to a different microstructure in each of the studied cases (1, 3 and 7 days of magnetic stirring time). This is due to the fact that the addition of these two compounds leads to a considerable increase in gelation time as GLY can interact with the alkoxide group on the surface of the iron oxide precursor micelle and/or be incorporated into the hydrophilic chains of CTAB. This last effect causes the iron oxide precursor micelles to be interconnected forming aggregates whose size and structure depend on the magnetic stirring time of the sol-gel synthetic route. In this paper, crystalline structure, composition, purity and morphology of the sol-gel coatings densified at 960 °C are examined. Emphasis is placed on the nominal percentage of the different iron oxides found in the samples and on the morphological and structural differences. This work implies the possibility of patterning ε-Fe2O3 nanoparticles in coatings and controlling their purity by an easy one-pot sol-gel method.

Strontium hexaferrite platelets: a comprehensive soft X-ray absorption and Mössbauer spectroscopy study.

Platelets of strontium hexaferrite (SrFe12O19, SFO), up to several micrometers in width, and tens of nanometers thick have been synthesized by a hydrothermal method. They have been studied by a combination of structural and magnetic techniques, with emphasis on Mössbauer spectroscopy and X-ray absorption based-measurements including spectroscopy and microscopy on the iron-L edges and the oxygen-K edge, allowing us to establish the differences and similarities between our synthesized nanostructures and commercial powders. The Mössbauer spectra reveal a greater contribution of iron tetrahedral sites in platelets in comparison to pure bulk material. For reference, high-resolution absorption and dichroic spectra have also been measured both from the platelets and from pure bulk material. The O-K edge has been reproduced by density functional theory calculations. Out-of-plane domains were observed with 180° domain walls less than 20 nm width, in good agreement with micromagnetic simulations.

On the effect of nanocrystallization and disorder on the magnetic properties of Cu-rich, FeMnCu alloys.

We report on the temperature dependencies of the Mössbauer spectra and the AC magnetic susceptibility measured in Cu-rich, FeMnCu samples prepared by mechanically alloying, using, on the one side, Cu and prealloyed FeMn powders and, on the other, pure element Cu, Mn, and Fe powders. From the correlation of the Mössbauer and susceptibility data we conclude about the basic characteristics of the phase distributions present in the different studied samples. Those distributions are a consequence of both the nanostructure induced upon milling and of the different signs of the Mn/Cu (negative) and Fe/Cu (positive) enthalpies of mixing. The proposed phase distributions are significantly different in the samples prepared from different precursors and this fact is analyzed in terms of the disproportion of the precursor FeMn alloy and in those of the favoured Mn/Cu interdiffusion and the hindered Fe/Cu one.

Origin of the magnetic transition at 100 K in ε-Fe2O3 nanoparticles studied by x-ray absorption fine structure spectroscopy.

The current study unveils the structural origin of the magnetic transition of the ε-Fe2O3 polymorph from an incommensurate magnetic order to a collinear ferrimagnetic state at low temperature. The high crystallinity of the samples and the absence of other iron oxide polymorphs have allowed us to carry out temperature-dependent x-ray absorption fine structure spectroscopy experiments out. The deformation of the structure is followed by the Debye-Waller factor for each selected Fe-O and Fe-Fe sub-shell. For nanoparticle sizes between 7 and 15 nm, the structural distortions between the Fete and Fe-D1oc sites are localized in a temperature range before the magnetic transition starts. On the contrary, the inherent interaction between the other sub-shells (named Fe-O1,2 and Fe-Fe1) provokes cooperative magneto-structural changes in the same temperature range. This means that the Fete with Fe-D1oc polyhedron interaction seems to be uncoupled with temperature dealing with these nanoparticle sizes wherein the structural distortions are likely moderate due to surface effects.

Initial stages of FeO growth on Ru(0001).

We study how FeO wüstite films on Ru(0001) grow by oxygen-assisted molecular beam epitaxy at elevated temperatures (800­900 K). The nucleation and growth of FeO islands are observed in real time by low-energy electron microscopy (LEEM). When the growth is performed in an oxygen pressure of 10(−6) Torr, the islands are of bilayer thickness (Fe­O­Fe­O). In contrast, under a pressure of 10(−8) Torr, the islands are a single FeO layer thick. We propose that the film thickness is controlled by the concentration of oxygen adsorbed on the Ru. More specifically, when monolayer growth increases the adsorbed oxygen concentration above a limiting value, its growth is suppressed. Increasing the temperature at a fixed oxygen pressure decreases the density of FeO islands. However, the nucleation density is not a monotonic function of oxygen pressure.

Wavelength and pulse duration effects on laser induced changes on raw pigments used in paintings.

In this study, the reaction of widely used artist's pigments in raw form to pulsed laser radiation of different wavelengths and pulse duration was investigated. Vermilion, lead chromate and malachite (in the form of pellets) were irradiated using laser pulses of 500 fs at 248 nm, and pulses of 150 ps and 15 ns at 1064 and 213 nm. Optical microscopy, colorimetry, spectrofluorimetry, micro-Raman spectroscopy and X-ray photoelectron spectroscopy were employed to characterize the physicochemical changes induced to the pigments. Change of crystalline phase was identified for vermilion while reduction processes take place for lead chromate and malachite. It was found that these effects were minimized by application of ultraviolet ultrashort pulses (of femtosecond and picosecond duration) as compared with changes occurring by pulsed infrared irradiation (of both picosecond and nanosecond duration). The results presented are discussed in relation to previous research on painted mock-ups in order to elucidate the role and significance of the binding media in the laser induced discoloration of painted surfaces and thus to propose optimum laser cleaning practices.

Loss of TCR-beta F1 and/or EZRIN expression is associated with unfavorable prognosis in nodal peripheral T-cell lymphomas.

Nodal peripheral T-cell lymphoma (nodal PTCL) has an unfavorable prognosis, and specific pathogenic alterations have not been fully identified. The biological and clinical relevance of the expression of CD30/T-cell receptor (TCR) genes is a topic under active investigation. One-hundred and ninety-three consecutive nodal PTCLs (89 angioimmunoblastic T-cell lymphomas (AITL) and 104 PTCL-unspecified (PTCL-not otherwise specified (NOS)) cases) were analyzed for the immunohistochemical expression of 19 molecules, involving TCR/CD30 pathways and the associations with standard prognostic indices. Mutually exclusive expression was found between CD3 and TCR-beta F1 with CD30 expression. Taking all PTCL cases together, logistic regression identified a biological score (BS) including TCR molecules (TCR-beta F1 and EZRIN) that separates two subgroups of patients with a median survival of 34.57 and 5.20 months (P<0.001). Multivariate analysis identified BS and the prognostic index for PTCL (PIT) score as independent prognostic factors. This BS maintained its significance in multivariate analysis only for the PTCL-NOS subgroup of tumors. In AITL cases, only a high level of ki67 expression was related to prognosis. A BS including molecules involved in the TCR signaling pathway proved to be an independent prognostic factor of poor outcome in a multivariate analysis, specifically in PTCL-NOS patients. Nevertheless, validation in an independent series of homogeneously treated PTCL patients is required to confirm these data.

Magnetic interaction in ferrous antimonite, FeSb2O4, and some derivatives.

Ferrous antimonite, FeSb(2)O(4), which is isostructural with Pb(3)O(4), and some lead- and cobalt-doped variants of composition FeSb(1.5)Pb(0.5)O(4) and Co(0.5)Fe(0.5)Sb(1.5)Pb(0.5)O(4) have been examined by (57)Fe and (121)Sb Mössbauer spectroscopy. Antimony is present as Sb(3+). The presence of Pb(2+) on the antimony site induces partial oxidation of Fe(2+) to Fe(3+). There is no Verwey-type transition in which electrons are shared between iron in different oxidation states. The quasi-one-dimensional magnetic structure gives rise to situations in which weakly coupled Fe(2+) ions can coexist in a non-magnetic state alongside Fe(3+) ions in a magnetically ordered state.