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We investigated room-temperature metal and ligand K-edge X-ray absorption (XAS) spectra of a complete redox series of cubane-type iron-sulfur clusters. The Fe K-edge position provides a qualitative but convenient alternative to the traditional spectroscopic descriptors used to identify oxidation states in these systems, which we demonstrate by providing a calibration curve based on two analytic methods. Furthermore, high energy resolution fluorescence detected XAS (HERFD-XAS) at the S K-edge was used to measure Fe-S bond covalencies and record their variation with the average valence of the Fe atoms. While the Fe-S(thiolate) covalency evolves linearly, gaining 11 ± 0.4% per bond and hole, the Fe-S(μ 3 ) covalency evolves asystematically, reflecting changes in the magnetic exchange mechanism. A strong discontinuity manifested for superoxidation to the all-ferric state, distinguishing its electronic structure and its potential (bio)chemical role from those of its redox congeners. We highlight the functional implications of these trends for the reactivity of iron-sulfur cubanes., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Background: Abdominal venous thromboses are rare thrombotic events with heterogeneous etiologies. They are related to myeloproliferative neoplasms (MPNs) in some patients and can occur as first signs of the disease. MPNs are characterized by mutations in the genes of Janus kinase 2 (JAK2), myeloproliferative leukemia virus oncogene (MPL), and calreticulin (CALR)., Methods: Within the prospective trial "Prevalence of JAK2 mutations in patients with abdominal venous thromboses" (JAK2 MV study; German Clinical Trials Register: DRKS00026943), the peripheral blood of patients with abdominal venous thromboses in Mecklenburg-West Pomerania, a federal state located in north-east Germany, was analyzed by next-generation ultradeep sequencing for MPN-associated mutations. Clinical characteristics and blood cell counts were also of interest. The primary endpoint was the detection of the mutation JAK2 p.V617F. Secondary endpoints were the detection of other acquired variants of JAK2, as well as MPL and CALR., Results: A total of 68 patients with abdominal venous thromboses were included from February 2017 to January 2021, with splanchnic veins affected in 65 patients. The mutation JAK2 p.V617F was present in 13 patients (19%), with four patients showing low variant allele frequencies (VAF 0.1% to 1.9%). The time interval from the thrombotic event to analysis was longer for patients with the mutation. The mutation MPL p.W515R was detected in three cases, all of them with low VAF. One patient among them had a concurrent mutation of JAK2 p.V617F. The mutations CALR type I or type II were not found., Discussion: By analyzing peripheral blood for the mutation JAK2 p.V617F, an important cause of these rare thrombotic events can be identified. The development of a diagnostic workup with next-generation ultradeep sequencing for the analysis of the JAK2 p.V617F mutation and further mutations has the potential to better understand the etiology of abdominal venous thromboses in individual patients in regional clinical care, as abdominal venous thromboses are diagnosed by various medical disciplines., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Henze, Grunwald, Felser, Witte, Grosse-Thie, Roolf, Murua Escobar and Junghanss.)

We study whether neural quantum states based on multilayer feed-forward networks can find ground states which exhibit volume-law entanglement entropy. As a testbed, we employ the paradigmatic Sachdev-Ye-Kitaev model. We find that both shallow and deep feed-forward networks require an exponential number of parameters in order to represent the ground state of this model. This demonstrates that sufficiently complicated quantum states, although being physical solutions to relevant models and not pathological cases, can still be difficult to learn to the point of intractability at larger system sizes. Hence, the variational neural network approach offers no benefits over exact diagonalization methods in this case. This highlights the importance of further investigations into the physical properties of quantum states amenable to an efficient neural representation.

Introduction: Medical readiness to deploy is an increasingly important issue within the military. Musculoskeletal back pain is one of the most common medical problems that affects service members. This study demonstrates the associations between risk factors and the prevalence of musculoskeletal back pain among active duty sailors and Marines within the Department of the Navy (DoN)., Materials and Methods: Utilizing the Military Health System Data Repository, we conducted a retrospective cross-sectional review of administrative healthcare claim data for all active duty DoN personnel with at least one medical encounter during fiscal years 2009-2015. For each fiscal year, we identified all claims with an ICD-9 code for back pain and calculated prevalence. We compared those with and without back pain across all variables (age, gender, rank, race, body mass index, tobacco use, occupation, and branch of service) using chi-square analysis. Unadjusted and adjusted log-binomial regressions were used to calculate prevalence ratios and examine associated risk factors for back pain., Results: The number of active duty subjects per fiscal year ranged from 424,460 to 437,053. The prevalence of back pain showed an upward trend, ranging from 9.99% in 2009 to 12.09% in 2015. Personnel aged 35 years and older had the strongest adjusted prevalence ration (APR) for back pain (APR 2.59; 95% CI, 2.53-2.66). There were also strong associations with obese body mass index (APR 1.76; 95% CI, 1.66-1.86), overweight body mass index (APR 1.29; 95% CI, 1.27-1.32), and tobacco use (APR 1.39; 95% CI, 1.36-1.42). Females were more likely to have back pain than males (APR 1.43; 95% CI, 1.40-1.47) and Marines more likely than sailors (APR 1.39; 95% CI, 1.36-1.42). The occupation with the highest prevalence ratio was healthcare (APR 1.34; 95% CI, 1.29-1.40) when compared to the reference group of combat specialists., Conclusions: There was an increasing prevalence of back pain across the DoN from 2009 to 2015. Different occupational categories demonstrate different prevalence of back pain. Surprisingly, combat occupations and aviators were among the groups with the lowest prevalence. Lifestyle factors such as excess body weight and use of tobacco products are clearly associated with increased prevalence. These results could inform military leaders with regard to setting policies that could increase medical readiness., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2021. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Introduction: There are approximately 1.5 million U.S. military-dependent children. However, little is known about mental health referrals for these youths. This study sought to examine the type of mental health treatment referrals made by primary care providers for child military-dependent beneficiaries receiving care in the direct (within Military Treatment Facilities) and private care (civilian-fee-for service facilities) sectors of the Military Health System., Materials and Methods: A between-subjects, cross-sectional study was performed on children aged 5-18 years old in fiscal years 2011-2015 and enrolled in TRICARE Prime. Study analyses examined specialty ("talk therapy") mental health care and psychotropic medication referrals from TRICARE Prime (the Defense Health Agency-managed health care program) providers for beneficiary children diagnosed with attention-, mood-, anxiety-, or behavior-related disorders in direct versus private sector care., Results: Of 1,533,630 children enrolled in TRICARE Prime (50.03% female), 8.6% (n = 131,393) were diagnosed with a psychological disorder during FY 2011-2015. Most were attention-related (5.2%, n = 79,770), followed by mood (1.7%, n = 25,314), anxiety (1.1%, n = 16,155), and conduct-related diagnoses (0.7%, n = 10,154). Adjusting for age, sex, and sponsor rank, children within direct care diagnosed with attention-related disorders were 1.7 times more likely to receive a prescription for psychotropic medication than those in private sector care, odds ratio (OR) = 1.72, 95% confidence interval (CI): [1.66, 1.77]. Children diagnosed with mood-related disorders in direct care were 2.1 times more likely to receive a prescription for psychotropic medication than those in private sector care, OR = 2.08, 95% CI: [1.96, 2.21]. Across disorders, children who received private sector care were more likely to have a referral specialty mental health ("talk therapy") follow-up (ps < 0.0001)., Conclusions: For attention- and mood-related disorders, but not anxiety- or conduct-related disorders, direct care providers were more likely than private sector care providers to prescribe psychotropic medications. Inconsistencies of provider referrals within and outside of the Military Health System should be elucidated to determine the impact on outcomes., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2022. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

As key intermediates in metal-catalyzed nitrogen-transfer chemistry, terminal imido complexes of iron have attracted significant attention for a long time. In search of versatile model compounds, the recently developed second-generation N -anchored tris -NHC chelating ligand t ris -[2-(3-mesityl- im idazole-2-ylidene)- m ethyl]ami n e (TIMMN Mes ) was utilized to synthesize and compare two series of mid- to high-valent iron alkyl imido complexes, including a reactive Fe(V) adamantyl imido intermediate en route to an isolable Fe(V) nitrido complex. The chemistry toward the iron adamantyl imides was achieved by reacting the Fe(I) precursor [(TIMMN Mes )Fe I (N 2 )] + ( 1 ) with 1-adamantyl azide to yield the corresponding trivalent iron imide. Stepwise chemical reduction and oxidation lead to the isostructural series of low-spin [(TIMMN Mes )Fe(NAd)] 0,1+,2+,3+ ( 2 Ad - 5 Ad ) in oxidation states II to V. The Fe(V) imide [(TIMMN Mes )Fe(NAd)] 3+ ( 5 Ad ) is unstable under ambient conditions and converts to the air-stable nitride [(TIMMN Mes )Fe V (N)] 2+ ( 6 ) via N-C bond cleavage. The stability of the pentavalent imide can be increased by derivatizing the nitride [(TIMMN Mes )Fe IV (N)] + ( 7 ) with an ethyl group using the triethyloxonium salt Et 3 OPF 6 . This gives access to the analogous series of ethyl imides [(TIMMN Mes )Fe(NEt)] 0,1+,2+,3+ ( 2 Et - 5 Et ), including the stable Fe(V) ethyl imide. Iron imido complexes exist in a manifold of different electronic structures, ultimately controlling their diverse reactivities. Accordingly, these complexes were characterized by single-crystal X-ray diffraction analyses, SQUID magnetization, and electrochemical methods, as well as 57 Fe Mössbauer, IR vibrational, UV/vis electronic absorption, multinuclear NMR, X-band EPR, and X-ray absorption spectroscopy. Our studies are complemented with quantum chemical calculations, thus providing further insight into the electronic structures of all complexes.

Synthetic iron-sulfur cubanes are models for biological cofactors, which are essential to delineate oxidation states in the more complex enzymatic systems. However, a complete series of [Fe 4 S 4 ] n complexes spanning all redox states accessible by 1-electron transformations of the individual iron atoms ( n = 0-4+) has never been prepared, deterring the methodical comparison of structure and spectroscopic signature. Here, we demonstrate that the use of a bulky arylthiolate ligand promoting the encapsulation of alkali-metal cations in the vicinity of the cubane enables the synthesis of such a series. Characterization by EPR, 57 Fe Mössbauer spectroscopy, UV-visible electronic absorption, variable-temperature X-ray diffraction analysis, and cyclic voltammetry reveals key trends for the geometry of the Fe 4 S 4 core as well as for the Mössbauer isomer shift, which both correlate systematically with oxidation state. Furthermore, we confirm the S = 4 electronic ground state of the most reduced member of the series, [Fe 4 S 4 ] 0 , and provide electrochemical evidence that it is accessible within 0.82 V from the [Fe 4 S 4 ] 2+ state, highlighting its relevance as a mimic of the nitrogenase iron protein cluster.