Optical Pooled Screens in Human Cells.

Genetic screens are critical for the systematic identification of genes underlying cellular phenotypes. Pooling gene perturbations greatly improves scalability but is not compatible with imaging of complex and dynamic cellular phenotypes. Here, we introduce a pooled approach for optical genetic screens in mammalian cells. We use targeted in situ sequencing to demultiplex a library of genetic perturbations following image-based phenotyping. We screened a set of 952 genes across millions of cells for involvement in nuclear factor κB (NF-κB) signaling by imaging the translocation of RelA (p65) to the nucleus. Screening at a single time point across 3 cell lines recovered 15 known pathway components, while repeating the screen with live-cell imaging revealed a role for Mediator complex subunits in regulating the duration of p65 nuclear retention. These results establish a highly multiplexed approach to image-based screens of spatially and temporally defined phenotypes with pooled libraries.

A genome-wide optical pooled screen reveals regulators of cellular antiviral responses.

The infection of mammalian cells by viruses and innate immune responses to infection are spatiotemporally organized processes. Cytosolic RNA sensors trigger nuclear translocation of the transcription factor interferon regulatory factor 3 (IRF3) and consequent induction of host immune responses to RNA viruses. Previous genetic screens for factors involved in viral sensing did not resolve changes in the subcellular localization of host or viral proteins. Here, we increased the throughput of our optical pooled screening technology by over fourfold. This allowed us to carry out a genome-wide CRISPR knockout screen using high-resolution multiparameter imaging of cellular responses to Sendai virus infection coupled with in situ cDNA sequencing by synthesis (SBS) to identify 80,408 single guide RNAs (sgRNAs) in 10,366,390 cells-over an order of magnitude more genomic perturbations than demonstrated previously using an in situ SBS readout. By ranking perturbations using human-designed and deep learning image feature scores, we identified regulators of IRF3 translocation, Sendai virus localization, and peroxisomal biogenesis. Among the hits, we found that ATP13A1, an ER-localized P5A-type ATPase, is essential for viral sensing and is required for targeting of mitochondrial antiviral signaling protein (MAVS) to mitochondrial membranes where MAVS must be localized for effective signaling through retinoic acid-inducible gene I (RIG-I). The ability to carry out genome-wide pooled screens with complex high-resolution image-based phenotyping dramatically expands the scope of functional genomics approaches.

Validation of an interprofessional education search strategy in PubMed to optimize IPE literature searching.

Objective: With exponential growth in the publication of interprofessional education (IPE) research studies, it has become more difficult to find relevant literature and stay abreast of the latest research. To address this gap, we developed, evaluated, and validated search strategies for IPE studies in PubMed, to improve future access to and synthesis of IPE research. These search strategies, or search hedges, provide comprehensive, validated sets of search terms for IPE publications. Methods: The search strategies were created for PubMed using relative recall methodology. The research methods followed the guidance of previous search hedge and search filter validation studies in creating a gold standard set of relevant references using systematic reviews, having expert searchers identify and test search terms, and using relative recall calculations to validate the searches' performance against the gold standard set. Results: The three recommended search hedges for IPE studies presented had recall of 71.5%, 82.7%, and 95.1%; the first more focused for efficient literature searching, the last with high recall for comprehensive literature searching, and the remaining hedge as a middle ground between the other two options. Conclusion: These validated search hedges can be used in PubMed to expedite finding relevant scholarships, staying up to date with IPE research, and conducting literature reviews and evidence syntheses.

The role of extracorporeal membrane oxygenation in adult kidney transplant patients: A qualitative systematic review of literature.

BACKGROUND: A paucity of evidence exists regarding the risks and benefits of Extracorporeal Membrane Oxygenation (ECMO) in adult kidney transplantation. METHODS: This was a systematic review conducted from Jan 1, 2000 to April 24, 2020 of adult kidney transplant recipients (pre- or post- transplant) and donors who underwent veno-arterial or veno-venous ECMO cannulation. Death and graft function were the primary outcomes, with complications as secondary outcomes. RESULTS: Twenty-three articles were identified that fit inclusion criteria. 461 donors were placed on ECMO, with an overall recipient 12-month mortality rate of 1.3% and a complication rate of 61.5%, the majority of which was delayed graft function. Fourteen recipients were placed on ECMO intraoperatively or postoperatively, with infection as the most common indication for ECMO. The 90-day mortality rate for recipients on ECMO was 42.9%, with multisystem organ failure and infection as the ubiquitous causes of death. 35.7% of patients experienced rejection within 6 months of decannulation, yet all were successfully treated. CONCLUSIONS: ECMO use in adult kidney transplantation is a useful adjunct. Recipient morbidity and mortality from donors placed on ECMO mirrors that of recipients from standard criteria donors. The morbidity and mortality of recipients placed on ECMO are also similar to other patient populations requiring ECMO.

The role of extracorporeal membrane oxygenation in adult liver transplant patients: A qualitative systematic review of literature.

BACKGROUND: A paucity of evidence exists regarding risks and benefits of extracorporeal membrane oxygenation (ECMO) in adult liver transplantation. METHODS: This was a systematic review conducted from January 1, 2000 to April 24, 2020 of adult liver transplant recipients (pre- or post-transplant) and donors who underwent Veno-arterial or Veno-venous ECMO cannulation. Death was the primary outcome, with graft function and complications as secondary outcomes. RESULTS: Forty-one articles were identified that fit criteria. A total of 183 donors were placed on ECMO, with recipient complication profiles and mortality that mirrored rates from standard criteria donors. Sixty-one recipients were placed on ECMO intraoperatively or postoperatively. Most patients experienced at least one complication with infections as the most common cause and minimal complications specifically related to ECMO use. Multisystem organ failure (MSOF) and infections were more common among liver recipients who died compared to those who survived. Overall mortality at 90 days was 45.9%. Causes of death were most commonly MSOF and infections. CONCLUSIONS: ECMO use in adult liver transplantation is a useful adjunct. Recipient morbidity and mortality from donors placed on ECMO parallel that of recipients from standard criteria donors, and morbidity and mortality of recipients placed on ECMO are similar to other ECMO populations.

Educational and economic returns to cognitive ability in low- and middle-income countries: A systematic review.

There is growing interest to use early cognitive ability to predict schooling and employment outcomes in low- and middle-income countries (LMICs). Rather than using educational attainment and school enrollment as predictors of future economic growth or of improving an individual's earning potential, mounting evidence suggests that cognitive ability may be a better predictor. The relationship between cognitive ability, education, and employment are essential to predict future development in LMICs. We performed a systematic literature review and meta-analysis of the evidence regarding the relationship between cognitive ability and educational outcomes, and between cognitive ability and economic outcomes across LMICs. We searched peer-reviewed studies since 2000 that quantitatively measured these relationships. Based on an initial search of 3,766 records, we identified 14 studies, including 8 studies that examined the cognition-education link and 8 studies that assessed cognition-employment returns in LMICs. Identified studies showed that higher cognitive ability increased the probability of school enrollment, academic achievement, and educational attainment across LMICs. A meta-analysis of returns to wages from cognitive ability suggested that a standard deviation increase in cognitive test scores was associated with a 4.5% (95% CI 2.6%-9.6%) increase in wages. Investments into early cognitive development could play a critical role in improving educational and economic outcomes in LMICs. Further research should focus particularly in low-income countries with the least evidence, and examine the impact on education and economic outcomes by cognitive domains to provide more robust evidence for policy makers to take action.

The role of extracorporeal membrane oxygenation in pediatric abdominal transplant patients: A qualitative systematic review of literature.

BACKGROUND: Advances in ECMO have made it a useful adjunct in critically ill pediatric patients; however, a dearth of evidence exists regarding risks and benefits in pediatric abdominal transplantation. The purpose of this study was to perform a qualitative systematic review of outcomes in pediatric patients undergoing ECMO support pre- or post-abdominal organ transplantation. METHODS: This was a systematic review conducted from Jan 1, 1989, to April 24, 2020, via PubMed, Embase, Scopus, Web of Science, the Cochrane Library, and ClinicalTrials.gov of all pediatric solid abdominal organ transplant recipients (pre- and post-transplant) and donors who underwent V-A or V-V ECMO cannulation. Death was the primary outcome, with graft function and complications as secondary outcomes. RESULTS: Fourteen articles were identified that fit criteria, with 88% being case reports. Three patients were donors placed on ECMO, with no mortality among the 8 recipients of organs from these donors. Nineteen recipients were placed on ECMO. All were liver transplants. Most patients experienced at least one complication (84%), with bleeding as the most common cause (44%). Mortality was 26%. Causes of death included multiorgan system failure (n = 3), heart failure (n = 1), Systemic inflammatory response syndrome (n = 1), abdominal compartment syndrome (n = 3), bleeding (n = 1), septic shock from aspergillus (n = 1), and hepatic artery thrombosis (n = 2). CONCLUSIONS: The data are poor on ECMO usage in pediatric abdominal transplantation. While complications were high, mortality did not appear to be related to ECMO usage and was relatively low given the severity of patient illness.

Interprofessional collaboration and barriers among health and social workers caring for older adults: a Philippine case study.

BACKGROUND: There is limited information on how the barriers to interprofessional collaboration (IPC) across various professionals, organizations, and care facilities influence the health and welfare of older adults. This study aimed to describe the status of IPC practices among health and social workers providing care for older adults in the Philippines; investigate the perceived barriers to its implementation and perceived effects on geriatric care; and identify possible solutions to address the barriers limiting collaborative practice. METHODS: A case study approach was utilized employing 12 semi-structured in-depth interviews and 29 focus group discussions with care workers from selected primary health care units, public and private hospitals, and nursing homes that are directly involved in geriatric care delivery in two cities in the Philippines. Overall, 174 health and social workers consented to participate in this study. All interviews were audio-recorded and transcribed verbatim. An inductive thematic analysis using NVivo 12® was used to identify and categorize relevant thematic codes. RESULTS: Interprofessional geriatric care provided by health and social workers was observed to be currently limited to ad hoc communications typically addressing only administrative concerns. This limitation is imposed by a confluence of barriers such as personal values and beliefs, organizational resource constraints, and a silo system care culture which practitioners say negatively influences care delivery. This in turn results in inability of care providers to access adequate care information, as well as delays and renders inaccessible available care provided to vulnerable older adults. Uncoordinated care of older adults also led to reported inefficient duplication and overlap of interventions. CONCLUSION: Geriatric care workers fear such barriers may aggravate the increasing unmet needs of older adults. In order to address these potential negative outcomes, establishing a clear and committed system of governance that includes IPC is perceived as necessary to install a cohesive service delivery mechanism and provide holistic care for older adults. Future studies are needed to measure the effects of identified barriers on the potential of IPC to facilitate an integrated health and social service delivery system for the improvement of quality of life of older adults in the Philippines.

Essential Services of Clinical Librarians in Academic and Health Care Settings: A Cross-Sectional Study.

This article provides a comprehensive summary of clinical librarian service models in the US, Canada, and the UK from a cross-sectional study. An online survey received 182 responses from clinical librarians in hospital (62%), academic (26%), and other (10%) libraries. These clinical librarians shared the services they provide, patrons they work with, and their perceptions of the value they add to clinical environments. Overall, this study quantifies the services offered most frequently by clinical librarians, the services felt to be most valuable, and the variety of health care clientele whom clinical librarians serve. These findings have implications for current clinical librarians, libraries and health care institutions, and for those who may become clinical librarians in the future.

Mechanistic Study of the Production of NOx Gases from the Reaction of Copper with Nitric Acid.

Copper dissolution in nitric acid is a historic reaction playing a central role in many industrial processes, particularly for metal recovery from the electronics to nuclear industries. The mechanism through which this process occurs is debated. In order to better understand this process, quantum chemical calculations were performed to elucidate the key steps in the mechanism of copper dissolution in nitric acid. We combine both Kohn-Sham density functional theory and ab initio molecular dynamics simulations to understand the mechanism of the formation of the key products: NO2, HNO2, and NO. Our calculations suggest that the mechanisms of formation of NO2, HNO2, and NO are interconnected.

On-Top Ratio for Atoms and Molecules.

The on-top ratio, R, is the ratio of the on-top pair density to the square of half the total density. Here, we explore the on-top ratio as a tool to understand different types of bonds, including covalent, polar covalent, ionic, and dispersion-dominated weak interactions. We show for several diatomic molecules and for ethylene that the partial derivative of R is a useful indicator of covalent-bond breaking. R also presents a local maximum for each electron shell when all electrons are correlated.

Multiconfiguration Pair-Density Functional Theory: A New Way To Treat Strongly Correlated Systems.

The electronic energy of a system provides the Born-Oppenheimer potential energy for internuclear motion and thus determines molecular structure and spectra, bond energies, conformational energies, reaction barrier heights, and vibrational frequencies. The development of more efficient and more accurate ways to calculate the electronic energy of systems with inherently multiconfigurational electronic structure is essential for many applications, including transition metal and actinide chemistry, systems with partially broken bonds, many transition states, and most electronically excited states. Inherently multiconfigurational systems are called strongly correlated systems or multireference systems, where the latter name refers to the need for using more than one ("multiple") configuration state function to provide a good zero-order reference wave function. This Account describes multiconfiguration pair-density functional theory (MC-PDFT), which was developed as a way to combine the advantages of wave function theory (WFT) and density functional theory (DFT) to provide a better treatment of strongly correlated systems. First we review background material: the widely used Kohn-Sham DFT (which uses only a single Slater determinant as reference wave function), multiconfiguration WFT methods that treat inherently multiconfigurational systems based on an active space, and previous attempts to combine multiconfiguration WFT with DFT. Then we review the formulation of MC-PDFT. It is a generalization of Kohn-Sham DFT in that the electron kinetic energy and classical electrostatic energy are calculated from a reference wave function, while the rest of the energy is obtained from a density functional. However, there are two main differences with respent to Kohn-Sham DFT: (i) The reference wave function is multiconfigurational rather than being a single Slater determinant. (ii) The density functional is a function of the total density and the on-top pair density rather than being a function of the spin-up and spin-down densities. In work carried out so far, the multiconfigurational wave function is a multiconfiguration self-consistent-field wave function. The new formulation has the advantage that the reference wave function has the correct spatial and spin symmetry and can describe bond dissociation (of both single and multiple bonds) and electronic excitations in a formally and physically correct way. We then review the formulation of density functionals in terms of the on-top pair density. Finally we review successful applications of the theory to bond energies and bond dissociation potential energy curves of main-group and transition metal bonds, to barrier heights (including pericyclic reactions), to proton affinities, to the hydrogen bond energy of water dimer, to ground- and excited-state charge transfer, to valence and Rydberg excitations of molecules, and to singlet-triplet splittings of radicals. We find that that MC-PDFT can give accurate results not only with complete-active-space multiconfiguration wave functions but also with generalized-active-space multiconfiguration wave functions, which are practical for larger numbers of active electrons and active orbitals than are complete-active-space wave functions. The separated-pair approximation, which is a special case of generalized active space self-consistent-field theory, is especially promising. MC-PDFT, because it requires much less computer time and storage than pure WFT methods, has the potential to open larger and more complex strongly correlated systems to accurate simulation.

On-Top Pair Density as a Measure of Left-Right Correlation in Bond Breaking.

To better understand left-right electron correlation and the effect of bond breaking on the on-top pair density, analytic expressions for the total density, the on-top pair density, and the ratio of the on-top pair density to the square of the total density were derived for H2 for both a restricted Hartree-Fock wave function and a complete active space self-consistent-field wave function with two electrons in two active orbitals. These quantities are compared for the two wave functions for various points in space around the molecule as functions of internuclear distance. At some points in space, in the CASSCF(2,2) wave function, electron correlation, perhaps counterintuitively, increases the probability that two electrons are at the same point in space. At the Coulson-Fischer point, the on-top pair density for the complete active space wave function starts to rapidly approach zero, and this can be taken as an indicator of bond breaking.

Use of Brevibacillus choshinensis for the production of biologically active brain-derived neurotrophic factor (BDNF).

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family critical for neuronal cell survival and differentiation, with therapeutic potential for the treatment of neurological disorders and spinal cord injuries. The production of recombinant, bioactive BDNF is not practical in most traditional microbial expression systems because of the inability of the host to correctly form the characteristic cystine-knot fold of BDNF. Here, we investigated Brevibacillus choshinensis as a suitable expression host for bioactive BDNF expression, evaluating the effects of medium type (2SY and TM), temperature (25 and 30 °C), and culture time (48-120 h). Maximal BDNF bioactivity (per unit mass) was observed in cultures grown in 2SY medium at extended times (96 h at 30 °C or >72 h at 25 °C), with resulting bioactivity comparable to that of a commercially available BDNF. For cultures grown in 2SY medium at 25 °C for 72 h, the condition that led to the greatest quantity of biologically active protein in the shortest culture time, we recovered 264 µg/L of BDNF. As with other microbial expression systems, BDNF aggregates did form in all culture conditions, indicating that while we were able to recover biologically active BDNF, further optimization of the expression system could yield still greater quantities of bioactive protein. This study provides confirmation that B. choshinensis is capable of producing biologically active BDNF and that further optimization of culture conditions could prove valuable in increasing BDNF yields.

Molcas 8: New capabilities for multiconfigurational quantum chemical calculations across the periodic table.

In this report, we summarize and describe the recent unique updates and additions to the Molcas quantum chemistry program suite as contained in release version 8. These updates include natural and spin orbitals for studies of magnetic properties, local and linear scaling methods for the Douglas-Kroll-Hess transformation, the generalized active space concept in MCSCF methods, a combination of multiconfigurational wave functions with density functional theory in the MC-PDFT method, additional methods for computation of magnetic properties, methods for diabatization, analytical gradients of state average complete active space SCF in association with density fitting, methods for constrained fragment optimization, large-scale parallel multireference configuration interaction including analytic gradients via the interface to the Columbus package, and approximations of the CASPT2 method to be used for computations of large systems. In addition, the report includes the description of a computational machinery for nonlinear optical spectroscopy through an interface to the QM/MM package Cobramm. Further, a module to run molecular dynamics simulations is added, two surface hopping algorithms are included to enable nonadiabatic calculations, and the DQ method for diabatization is added. Finally, we report on the subject of improvements with respects to alternative file options and parallelization.

Bimetallic cobalt-dinitrogen complexes: impact of the supporting metal on N2 activation.

Expanding a family of cobalt bimetallic complexes, we report the synthesis of the Ti(III) metalloligand, Ti[N(o-(NCH2P((i)Pr)2)C6H4)3] (abbreviated as TiL), and three heterobimetallics that pair cobalt with an early transition metal ion: CoTiL (1), K(crypt-222)[(N2)CoVL] (2), and K(crypt-222)[(N2)CoCrL] (3). The latter two complexes, along with previously reported K(crypt-222)[(N2)CoAlL] and K(crypt-222)[(N2)Co2L], constitute an isostructural series of cobalt bimetallics that bind dinitrogen in an end-on fashion, i.e. [(N2)CoML](-). The characterization of 1-3 includes cyclic voltammetry, X-ray crystallography, and infrared spectroscopy. The [CoTiL](0/-) reduction potential is extremely negative at -3.20 V versus Fc(+)/Fc. In the CoML series where M is a transition metal, the reduction potentials shift anodically as M is varied across the first-row period. Among the [(N2)CoML](-) compounds, the dinitrogen ligand is weakly activated, as evidenced by N-N bond lengths between 1.110(8) and 1.135(4) Å and by N-N stretching frequencies between 1971 and 1995 cm(-1). Though changes in νN2 are subtle, the extent of N2 activation decreases across the first-row period. A correlation is found between the [CoML](0/-) reduction potentials and N2 activation, where the more cathodic potentials correspond to lower N-N frequencies. Theoretical calculations of the [(N2)CoML](-) complexes reveal important variations in the electronic structure and Co-M interactions, which depend on the exact nature of the supporting metal ion, M.

Heterobimetallic Complexes That Bond Vanadium to Iron, Cobalt, and Nickel.

Zero-valent iron, cobalt, and nickel were installed into the metalloligand V[N(o-(NCH2P((i)Pr)2)C6H4)3] (1, VL), generating the heterobimetallic trio FeVL (2), CoVL (3), and NiVL (4), respectively. In addition, the one-electron-oxidized analogues [FeVL]X ([2(ox)]X, where X(-) = BPh4 or PF6) and [CoVL]BPh4 ([3(ox)]BPh4) were prepared. The complexes were characterized by a host of physical methods, including cyclic voltammetry, X-ray crystallography, magnetic susceptibility, electronic absorption, NMR, electron paramagnetic resonance (EPR), and Mössbauer spectroscopies. The CoV and FeV heterobimetallic compounds have short M-V bond lengths that are consistent with M-M multiple bonding. As revealed by theoretical calculations, the M-V bond is triple in 2, 2(ox), and 3(ox), double in 3, and dative (Ni → V) in 4. The (d-d)(10) species, 2 and 3(ox), are diamagnetic and exhibit large diamagnetic anisotropies of -4700 × 10(-36) m(3)/molecule. Complexes 2 and 3(ox) are also characterized by intense visible bands at 760 and 610 nm (ε > 1000 M(-1) cm(-1)), respectively, which correspond to an intermetal (M → V) charge-transfer transition. Magnetic susceptibility measurements and EPR characterization establish S = (1)/2 ground states for (d-d)(9) 2(ox) and (d-d)(11) 3, while (d-d)(12) 4 is S = 1 based on Evans' method.

Influence of Copper Oxidation State on the Bonding and Electronic Structure of Cobalt-Copper Complexes.

Heterobimetallic complexes that pair cobalt and copper were synthesized and characterized by a suite of physical methods, including X-ray diffraction, X-ray anomalous scattering, cyclic voltammetry, magnetometry, electronic absorption spectroscopy, electron paramagnetic resonance, and quantum chemical methods. Both Cu(II) and Cu(I) reagents were independently added to a Co(II) metalloligand to provide (py3tren)CoCuCl (1-Cl) and (py3tren)CoCu(CH3CN) (2-CH3CN), respectively, where py3tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. Complex 2-CH3CN can lose the acetonitrile ligand to generate a coordination polymer consistent with the formula "(py3tren)CoCu" (2). One-electron chemical oxidation of 2-CH3CN with AgOTf generated (py3tren)CoCuOTf (1-OTf). The Cu(II)/Cu(I) redox couple for 1-OTf and 2-CH3CN is reversible at -0.56 and -0.33 V vs Fc(+)/Fc, respectively. The copper oxidation state impacts the electronic structure of the heterobimetallic core, as well as the nature of the Co-Cu interaction. Quantum chemical calculations showed modest electron delocalization in the (CoCu)(+4) state via a Co-Cu σ bond that is weakened by partial population of the Co-Cu σ antibonding orbital. By contrast, no covalent Co-Cu bonding is predicted for the (CoCu)(+3) analogue, and the d-electrons are fully localized at individual metals.

Pushing the Limits of Delta Bonding in Metal-Chromium Complexes with Redox Changes and Metal Swapping.

Into the metalloligand Cr[N(o-(NCH2P((i)Pr)2)C6H4)3] (1, CrL) was inserted a second chromium atom to generate the dichromium complex Cr2L (2), which is a homobimetallic analogue of the known MCrL complexes, where M is manganese (3) or iron (4). The cationic and anionic counterparts, [MCrL](+) and [MCrL](-), respectively, were targeted, and each MCr pair was isolated in at least one other redox state. The solid-state structures of the [MCrL](+,0,-) redox members are essentially the same, with ultrashort metal-metal bonds between 1.96 and 1.74 Å. The formal shortness ratios (r) of these interactions are between 0.84 and 0.74 and are interpreted as triple to quintuple metal-metal bonds with the aid of theory. The trio of (d-d)(10) species [Cr2L](-) (2(red)), MnCrL (3), and [FeCrL](+) (4(ox)) are S = 0 diamagnets. On the basis of M-Cr bond distances and theoretical calculations, the strength of the metal-metal bond across the (d-d)(10) series increases in the order Fe < Mn < Cr. The methylene protons in the ligand are shifted downfield in the (1)H NMR spectra, and the diamagnetic anisotropy of the metal-metal bond was calculated as -3500 × 10(-36), -3900 × 10(-36), and -5800 × 10(-36) m(3) molecule(-1) for 2(red), 3, and 4(ox) respectively. The magnitude of diamagnetic anisotropy is, thus, affected more by bond polarity than by bond order. A comparative vis-NIR study of quintuply bonded 2(red) and 3 revealed a large red shift in the δ(4) → δ(3)δ* transition energy upon swapping from the (Cr2)(2+) to the (MnCr)(3+) core. Complex 2(red) was further investigated by resonance Raman spectroscopy, and a band at 434 cm(-1) was assigned as the Cr-Cr bond vibration. Finally, 4(ox) exhibited a Mössbauer doublet with an isomer shift of 0.18 mm/s that suggests a primarily Fe-based oxidation to Fe(I).