Selective Adsorption of Oxygen from Humid Air in a Metal-Organic Framework with Trigonal Pyramidal Copper(I) Sites.

High or enriched-purity O2 is used in numerous industries and is predominantly produced from the cryogenic distillation of air, an extremely capital- and energy-intensive process. There is significant interest in the development of new approaches for O2-selective air separations, including the use of metal-organic frameworks featuring coordinatively unsaturated metal sites that can selectively bind O2 over N2 via electron transfer. However, most of these materials exhibit appreciable and/or reversible O2 uptake only at low temperatures, and their open metal sites are also potential strong binding sites for the water present in air. Here, we study the framework CuI-MFU-4l (CuxZn5-xCl4-x(btdd)3; H2btdd = bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i])dibenzo[1,4]dioxin), which binds O2 reversibly at ambient temperature. We develop an optimized synthesis for the material to access a high density of trigonal pyramidal CuI sites, and we show that this material reversibly captures O2 from air at 25 °C, even in the presence of water. When exposed to air up to 100% relative humidity, CuI-MFU-4l retains a constant O2 capacity over the course of repeated cycling under dynamic breakthrough conditions. While this material simultaneously adsorbs N2, differences in O2 and N2 desorption kinetics allow for the isolation of high-purity O2 (>99%) under relatively mild regeneration conditions. Spectroscopic, magnetic, and computational analyses reveal that O2 binds to the copper(I) sites to form copper(II)-superoxide moieties that exhibit temperature-dependent side-on and end-on binding modes. Overall, these results suggest that CuI-MFU-4l is a promising material for the separation of O2 from ambient air, even without dehumidification.

High-Capacity, Cooperative CO2 Capture in a Diamine-Appended Metal-Organic Framework through a Combined Chemisorptive and Physisorptive Mechanism.

Diamine-appended Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) metal-organic frameworks are promising candidates for carbon capture that exhibit exceptional selectivities and high capacities for CO2. To date, CO2 uptake in these materials has been shown to occur predominantly via a chemisorption mechanism involving CO2 insertion at the amine-appended metal sites, a mechanism that limits the capacity of the material to ∼1 equiv of CO2 per diamine. Herein, we report a new framework, pip2-Mg2(dobpdc) (pip2 = 1-(2-aminoethyl)piperidine), that exhibits two-step CO2 uptake and achieves an unusually high CO2 capacity approaching 1.5 CO2 per diamine at saturation. Analysis of variable-pressure CO2 uptake in the material using solid-state nuclear magnetic resonance (NMR) spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveals that pip2-Mg2(dobpdc) captures CO2 via an unprecedented mechanism involving the initial insertion of CO2 to form ammonium carbamate chains at half of the sites in the material, followed by tandem cooperative chemisorption and physisorption. Powder X-ray diffraction analysis, supported by van der Waals-corrected density functional theory, reveals that physisorbed CO2 occupies a pocket formed by adjacent ammonium carbamate chains and the linker. Based on breakthrough and extended cycling experiments, pip2-Mg2(dobpdc) exhibits exceptional performance for CO2 capture under conditions relevant to the separation of CO2 from landfill gas. More broadly, these results highlight new opportunities for the fundamental design of diamine-Mg2(dobpdc) materials with even higher capacities than those predicted based on CO2 chemisorption alone.

Quantum chemical modeling of hydrogen binding in metal-organic frameworks: validation, insight, predictions and challenges.

A detailed chemical understanding of H2 interactions with binding sites in the nanoporous crystalline structure of metal-organic frameworks (MOFs) can lay a sound basis for the design of new sorbent materials. Computational quantum chemical calculations can aid in this quest. To set the stage, we review general thermodynamic considerations that control the usable storage capacity of a sorbent. We then discuss cluster modeling of H2 ligation at MOF binding sites using state-of-the-art density functional theory (DFT) calculations, and how the binding can be understood using energy decomposition analysis (EDA). Employing these tools, we illustrate the connections between the character of the MOF binding site and the associated adsorption thermodynamics using four experimentally characterized MOFs, highlighting the role of open metal sites (OMSs) in accessing binding strengths relevant to room temperature storage. The sorbents are MOF-5, with no open metal sites, Ni2(m-dobdc), containing Lewis acidic Ni(II) sites, Cu(I)-MFU-4l, containing π basic Cu(I) sites and V2Cl2.8(btdd), also containing π-basic V(II) sites. We next explore the potential for binding multiple H2 molecules at a single metal site, with thermodynamics useful for storage at ambient temperature; a materials design goal which has not yet been experimentally demonstrated. Computations on Ca2+ or Mg2+ bound to catecholate or Ca2+ bound to porphyrin show the potential for binding up to 4 H2; there is precedent for the inclusion of both catecholate and porphyrin motifs in MOFs. Turning to transition metals, we discuss the prediction that two H2 molecules can bind at V(II)-MFU-4l, a material that has been synthesized with solvent coordinated to the V(II) site. Additional calculations demonstrate binding three equivalents of hydrogen per OMS in Sc(I) or Ti(I)-exchanged MFU-4l. Overall, the results suggest promising prospects for experimentally realizing higher capacity hydrogen storage MOFs, if nontrivial synthetic and desolvation challenges can be overcome. Coupled with the unbounded chemical diversity of MOFs, there is ample scope for additional exploration and discovery.

Ambient-Temperature Hydrogen Storage via Vanadium(II)-Dihydrogen Complexation in a Metal-Organic Framework.

The widespread implementation of H2 as a fuel is currently hindered by the high pressures or cryogenic temperatures required to achieve reasonable storage densities. In contrast, the realization of materials that strongly and reversibly adsorb hydrogen at ambient temperatures and moderate pressures could transform the transportation sector and expand adoption of fuel cells in other applications. To date, however, no adsorbent has been identified that exhibits a binding enthalpy within the optimal range of -15 to -25 kJ/mol for ambient-temperature hydrogen storage. Here, we report the hydrogen adsorption properties of the metal-organic framework (MOF) V2Cl2.8(btdd) (H2btdd, bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i])dibenzo[1,4]dioxin), which features exposed vanadium(II) sites capable of backbonding with weak π acids. Significantly, gas adsorption data reveal that this material binds H2 with an enthalpy of -21 kJ/mol. This binding energy enables usable hydrogen capacities that exceed that of compressed storage under the same operating conditions. The Kubas-type vanadium(II)-dihydrogen complexation is characterized by a combination of techniques. From powder neutron diffraction data, a V-D2(centroid) distance of 1.966(8) Å is obtained, the shortest yet reported for a MOF. Using in situ infrared spectroscopy, the H-H stretch was identified, and it displays a red shift of 242 cm-1. Electronic structure calculations show that a main contribution to bonding stems from the interaction between the vanadium dπ and H2 σ* orbital. Ultimately, the pursuit of MOFs containing high densities of weakly π-basic metal sites may enable storage capacities under ambient conditions that far surpass those accessible with compressed gas storage.

Overcoming Metastable CO2 Adsorption in a Bulky Diamine-Appended Metal-Organic Framework.

Carbon capture at fossil fuel-fired power plants is a critical strategy to mitigate anthropogenic contributions to global warming, but widespread deployment of this technology is hindered by a lack of energy-efficient materials that can be optimized for CO2 capture from a specific flue gas. As a result of their tunable, step-shaped CO2 adsorption profiles, diamine-functionalized metal-organic frameworks (MOFs) of the form diamine-Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) are among the most promising materials for carbon capture applications. Here, we present a detailed investigation of dmen-Mg2(dobpdc) (dmen = 1,2-diamino-2-methylpropane), one of only two MOFs with an adsorption step near the optimal pressure for CO2 capture from coal flue gas. While prior characterization suggested that this material only adsorbs CO2 to half capacity (0.5 CO2 per diamine) at 1 bar, we show that the half-capacity state is actually a metastable intermediate. Under appropriate conditions, the MOF adsorbs CO2 to full capacity, but conversion from the half-capacity structure happens on a very slow time scale, rendering it inaccessible in traditional adsorption measurements. Data from solid-state magic angle spinning nuclear magnetic resonance spectroscopy, coupled with van der Waals-corrected density functional theory, indicate that ammonium carbamate chains formed at half capacity and full capacity adopt opposing configurations, and the need to convert between these states likely dictates the sluggish post-half-capacity uptake. By use of the more symmetric parent framework Mg2(pc-dobpdc) (pc-dobpdc4- = 3,3'-dioxidobiphenyl-4,4'-dicarboxylate), the metastable trap can be avoided and the full CO2 capacity of dmen-Mg2(pc-dobpdc) accessed under conditions relevant for carbon capture from coal-fired power plants.

Observation of an Intermediate to H2 Binding in a Metal-Organic Framework.

Coordinatively unsaturated metal sites within certain zeolites and metal-organic frameworks can strongly adsorb a wide array of substrates. While many classical examples involve electron-poor metal cations that interact with adsorbates largely through physical interactions, unsaturated electron-rich metal centers housed within porous frameworks can often chemisorb guests amenable to redox activity or covalent bond formation. Despite the promise that materials bearing such sites hold in addressing myriad challenges in gas separations and storage, very few studies have directly interrogated mechanisms of chemisorption at open metal sites within porous frameworks. Here, we show that nondissociative chemisorption of H2 at the trigonal pyramidal Cu+ sites in the metal-organic framework CuI-MFU-4l occurs via the intermediacy of a metastable physisorbed precursor species. In situ powder neutron diffraction experiments enable crystallographic characterization of this intermediate, the first time that this has been accomplished for any material. Evidence for a precursor intermediate is also afforded from temperature-programmed desorption and density functional theory calculations. The activation barrier separating the precursor species from the chemisorbed state is shown to correlate with a change in the Cu+ coordination environment that enhances π-backbonding with H2. Ultimately, these findings demonstrate that adsorption at framework metal sites does not always follow a concerted pathway and underscore the importance of probing kinetics in the design of next-generation adsorbents.

Selective nitrogen adsorption via backbonding in a metal-organic framework with exposed vanadium sites.

Industrial processes prominently feature π-acidic gases, and an adsorbent capable of selectively interacting with these molecules could enable important chemical separations1-4. Biological systems use accessible, reducing metal centres to bind and activate weakly π-acidic species, such as N2, through backbonding interactions5-7, and incorporating analogous moieties into a porous material should give rise to a similar adsorption mechanism for these gaseous substrates8. Here, we report a metal-organic framework featuring exposed vanadium(II) centres capable of back-donating electron density to weak π acids to successfully target π acidity for separation applications. This adsorption mechanism, together with a high concentration of available adsorption sites, results in record N2 capacities and selectivities for the removal of N2 from mixtures with CH4, while further enabling olefin/paraffin separations at elevated temperatures. Ultimately, incorporating such π-basic metal centres into porous materials offers a handle for capturing and activating key molecular species within next-generation adsorbents.

Evaluation of trauma resources in rural northern Alberta identifies opportunities for improvement.

Background: The care of rural trauma patients in northern Alberta can be extremely challenging because of the vast geographic area, the limited access to health care facilities and the lack of adequate resources to manage severe injuries. Identifying gaps in equipment and personnel in rural centres can provide opportunities for improving the care of injured patients in these environments. We conducted a survey based on Canadian Accreditation Council quality indicators to evaluate trauma infrastructure and human resources in rural centres across northern Alberta. Methods: A standardized survey was developed to assess the availability of trauma-specific equipment and personnel across the prehospital and emergency department (ED) settings. The survey was distributed to 50 peripheral hospitals biannually from January 2017 to September 2018. Two-tailed paired t tests were used to evaluate changes in survey responses; a p value of less than 0.05 was considered statistically significant. Results: The survey response rate was 100%. By the end of the study period, there were significant improvements in the number of providers (p = 0.04), nurses (p = 0.01) and dedicated trauma resuscitation bays (p = 0.04) in the ED for managing injured patients. There were also significant increases in the availability of equipment, including advanced airway management tools (p = 0.02), rapid infusion devices (p = 0.02) and warmers (p = 0.04). Access to x-ray equipment (p = 0.03) and computed tomography (CT) scanners (p = 0.04) as well as equipment to support telehealth and teleconferencing (p = 0.04) increased during the study period. Access to, and supply of, blood products also increased significantly (p = 0.02) during the study period. Conclusion: Our study demonstrates that the trauma resources of rural health care centres may be evaluated in a standardized fashion centres, and the results point to opportunities to remedy gaps in equipment and personnel. Our methods may be applied to any trauma network that serves geographically large areas with a sparse distribution of health care facilities, to provide critical information for the optimization of resources in rural trauma.

Contexte: Les soins aux patients victimes de traumatismes en région rurale dans le nord de l'Alberta peuvent être très difficiles en raison de la superficie de la région, de l'accès limité aux établissements de santé et du manque de ressources pour soigner adéquatement les blessures graves. En repérant les lacunes en équipement et en personnel dans les établissements en région rurale, on peut créer des occasions d'améliorer les soins aux patients blessés dans ces milieux. Nous avons mené un sondage fondé sur les indicateurs de qualité du Conseil d'accréditation canadien pour évaluer les infrastructures et les ressources humaines en traumatologie dans les établissements des régions rurales du nord de l'Alberta. Méthodes: Un sondage standardisé a été créé pour évaluer la disponibilité des équipements et des ressources humaines en traumatologie en contexte préhospitalier et aux services d'urgence. Le sondage a été distribué 2 fois par année à 50 hôpitaux entre janvier 2017 et septembre 2018. Des tests t appariés ayant une hypothèse non nulle ont été utilisés pour évaluer les changements dans les réponses au sondage; les résultats ayant une valeur p < 0,05 étaient considérés comme statistiquement significatifs. Résultats: Le taux de participation au sondage était de 100 %. À la fin de la période étudiée, il y avait une amélioration significative du nombre de fournisseurs (p = 0,04), de personnel infirmier (p = 0,01) et d'espaces de réanimation réservés à la traumatologie (p = 0,04) dans les services d'urgence. Il y avait aussi une augmentation significative de la disponibilité de l'équipement, notamment des outils de prise en charge avancée des voies respiratoires (p = 0,02), des appareils de perfusion rapide (p = 0,02) et d'armoires chauffantes (p = 0,04). Les équipements de radiographie (p = 0,03) et de tomographie par ordinateur (p = 0,04) ainsi que les équipements facilitant la télémédecine et les téléconférences (p = 0,04) sont devenus plus accessibles pendant la période étudiée. Les réserves de produits sanguins et l'accès à ces produits a aussi augmenté de manière significative (p = 0,02). Conclusion: Notre étude montre que les ressources en traumatologie dans les établissements de santé en région rurale peuvent être évaluées de manière standardisée, et les résultats indiquent qu'il y a des occasions de combler les lacunes en équipement et en personnel. Notres méthodes peuvent être reproduites dans tout réseau de traumatologie couvrant un grand territoire où les établissements de santé sont dispersés, pour fournir des données critiques sur l'organisation des ressources de traumatologie en région rurale.

Near-Perfect CO2/CH4 Selectivity Achieved through Reversible Guest Templating in the Flexible Metal-Organic Framework Co(bdp).

Metal-organic frameworks are among the most promising materials for industrial gas separations, including the removal of carbon dioxide from natural gas, although substantial improvements in adsorption selectivity are still sought. Herein, we use equilibrium adsorption experiments to demonstrate that the flexible metal-organic framework Co(bdp) (bdp2- = 1,4-benzenedipyrazolate) exhibits a large CO2 adsorption capacity and approaches complete exclusion of CH4 under 50:50 mixtures of the two gases, leading to outstanding CO2/CH4 selectivity under these conditions. In situ powder X-ray diffraction data indicate that this selectivity arises from reversible guest templating, in which the framework expands to form a CO2 clathrate and then collapses to the nontemplated phase upon desorption. Under an atmosphere dominated by CH4, Co(bdp) adsorbs minor amounts of CH4 along with CO2, highlighting the importance of studying all relevant pressure and composition ranges via multicomponent measurements when examining mixed-gas selectivity in structurally flexible materials. Altogether, these results show that Co(bdp) may be a promising CO2/CH4 separation material and provide insights for the further study of flexible adsorbents for gas separations.

Gram-positive pneumonia augments non-small cell lung cancer metastasis via host toll-like receptor 2 activation.

Surgical resection of early stage nonsmall cell lung cancer (NSCLC) is necessary for cure. However, rates of postoperative bacterial pneumonias remain high and may confer an increased risk for metastasis. Toll-like receptors (TLRs) mediate the inflammatory cascade by recognizing microbial products at the surface of numerous cell types in the lung; however, little is known about how host TLRs influence NSCLC metastasis. TLR2 recognizes gram-positive bacterial cell wall components activating innate immunity. We demonstrate that lower respiratory tract infection with Streptococcus pneumonia augments the formation of murine H59 NSCLC liver metastases in C57BL/6 mice through host TLR2 activation. Infected mice demonstrate increased H59 and human A549 NSCLC adhesion to hepatic sinusoids in vivo compared with noninfected controls, a response that is significantly diminished in TLR2 knock-out mice. Intra-tracheal injection of purified TLR2 ligand lipoteichoic acid into mice similarly augments in vivo adhesion of H59 cells to hepatic sinusoids. Additionally, H59 and A549 NSCLC cells incubated with bronchoepithelial conditioned media show increased cell adhesion to extracellular matrix components in vitro and hepatic sinusoids in vivo in a manner that is dependent on bronchoepithelial TLR2 activation and interleukin-6 secretion. TLR2 is therefore a potential therapeutic target for gram-positive pneumonia-driven NSCLC metastasis.

Transanal minimally invasive surgery for benign large rectal polyps and early malignant rectal cancers: experience and outcomes from the first Canadian centre to adopt the technique.

BACKGROUND: Transanal minimally invasive surgery (TAMIS) has emerged as a relatively new technique in treating early cancer and benign lesion of the rectum. The technique is likely to be widely adopted, surpassing other comparable techniques owing to its simple setup and cost-effectiveness. We assessed the outcomes of TAMIS at our centre. METHODS: We retrospectively reviewed prospectively collected data on 50 patients who underwent TAMIS for benign, malignant T1 or T2 cancers that were unfit for radical surgery over a 4-year period. Outcomes, including 30-day complications and recurrence, as well as our ability to implement and integrate this technique at our centre were assessed. RESULTS: All 50 TAMIS procedures were successful. The average lesion was 7 cm from the anal verge, the average tumour size was 2.5 cm, the average duration of surgery was 73 minutes, the average length of stay was 1.1 days, and the margin negativity was 84%. Major indications in our series included 25 lesions that were too large for endoscopic resection, 14 early cancers or high-grade dysplasia, 10 margin checks postpolypectomy, 6 cases of recurrent polyposis, and 4 medically unfit patients. There were no deaths. The rate of short-term complications, including rectal bleeding, reoperation and urinary retention, was 16%. The rate of long-term complications, including anal incontinence and stenosis, was 4%. Benign and malignant recurrence rates were 2% and 6%, respectively. Overall long-term requirement for invasive procedures, low anterior resection or abdominoperineal resection, was 12%. CONCLUSION: To our knowledge, this is the first Canadian study showing TAMIS to be an efficient and safe procedure for the treatment of well-selected patients with rectal lesions. Outcomes from our centre are comparable with those found in the literature.

CONTEXTE: La chirurgie transanale mini-invasive (TAMIS) s'est imposée comme une technique relativement nouvelle pour le traitement du cancer précoce et des lésions bénignes du rectum. La technique est en voie d'être adoptée à grande échelle, voire de supplanter d'autres techniques comparables, en raison de sa mise en place facile et de sa rentabilité. Nous avons évalué les résultats de la technique TAMIS dans notre centre. MÉTHODES: Nous avons fait une analyse rétrospective de données recueillies de façon prospective sur 50 patients traités par TAMIS pour cause de cancer T1 ou T2 malin ou bénin et non candidats à la chirurgie radicale, sur une période de 4 ans. Nous avons évalué les résultats, y compris les complications et la récidive sur 30 jours, ainsi que notre capacité d'adopter et d'intégrer cette technique dans notre centre. RÉSULTATS: Les 50 chirurgies TAMIS furent une réussite. La taille moyenne de la lésion était de 7 cm à partir de la marge anale, la taille moyenne de la tumeur était de 2,5 cm, la durée moyenne de la chirurgie était de 73 minutes, la durée moyenne d'hospitalisation était de 1,1 jour et le taux de marges négatives était de 84 %. Parmi les principales indications dans notre série, mentionnons 25 lésions trop grandes pour la résection endoscopique; 14 cancers précoces ou dysplasies de haut grade; 10 vérifications des marges post-polypectomie, 6 cas de récidive de la polypose et 4 patients non candidats au traitement médical. Il n'y a eu aucun décès. Le taux de complications à court terme, incluant le saignement rectal, les interventions répétées et la rétention urinaire, était de 16 %. Le taux de complications à long terme, incluant l'incontinence anale et la sténose anale, était de 4 %. Les taux de récidive bénigne et maligne étaient respectivement de 2 % et de 6 %. Le taux global de besoin à long terme d'une intervention effractive, d'une résection antérieure basse ou d'une résection abdominopérinéale était de 12 %. CONCLUSION: À notre connaissance, notre étude est la première au Canada qui démontre que la technique TAMIS est une intervention efficace et sécuritaire pour le traitement de patients soigneusement choisis atteints de lésions rectales. Les résultats de notre centre sont comparables à ceux trouvés dans la littérature.

Olsalazine-Based Metal-Organic Frameworks as Biocompatible Platforms for H2 Adsorption and Drug Delivery.

The drug olsalazine (H4olz) was employed as a ligand to synthesize a new series of mesoporous metal-organic frameworks that are expanded analogues of the well-known M2(dobdc) materials (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate; M-MOF-74). The M2(olz) frameworks (M = Mg, Fe, Co, Ni, and Zn) exhibit high surface areas with large hexagonal pore apertures that are approximately 27 Å in diameter. Variable temperature H2 adsorption isotherms revealed strong adsorption at the open metal sites, and in situ infrared spectroscopy experiments on Mg2(olz) and Ni2(olz) were used to determine site-specific H2 binding enthalpies. In addition to its capabilities for gas sorption, the highly biocompatible Mg2(olz) framework was also evaluated as a platform for the delivery of olsalazine and other encapsulated therapeutics. The Mg2(olz) material (86 wt % olsalazine) was shown to release the therapeutic linker through dissolution of the framework under simulated physiological conditions. Furthermore, Mg2(olz) was used to encapsulate phenethylamine (PEA), a model drug for a broad class of bioactive compounds. Under simulated physiological conditions, Mg2(olz)(PEA)2 disassembled to release PEA from the pores and olsalazine from the framework itself, demonstrating that multiple therapeutic components can be delivered together at different rates. The low toxicity, high surface areas, and coordinatively unsaturated metal sites make these M2(olz) materials promising for a range of potential applications, including drug delivery in the treatment of gastrointestinal diseases.

Long Duration Energy Storage Using Hydrogen in Metal-Organic Frameworks: Opportunities and Challenges.

Materials-based H2 storage plays a critical role in facilitating H2 as a low-carbon energy carrier, but there remains limited guidance on the technical performance necessary for specific applications. Metal-organic framework (MOF) adsorbents have shown potential in power applications, but need to demonstrate economic promises against incumbent compressed H2 storage. Herein, we evaluate the potential impact of material properties, charge/discharge patterns, and propose targets for MOFs' deployment in long-duration energy storage applications including backup, load optimization, and hybrid power. We find that state-of-the-art MOF could outperform cryogenic storage and 350 bar compressed storage in applications requiring ≤8 cycles per year, but need ≥5 g/L increase in uptake to be cost-competitive for applications that require ≥30 cycles per year. Existing challenges include manufacturing at scale and quantifying the economic value of lower-pressure storage. Lastly, future research needs are identified including integrating thermodynamic effects and degradation mechanisms.

Prophylactic cerebrospinal fluid drainage and spinal cord ischemia in thoracic and thoracoabdominal endovascular procedures: a systematic review and meta-analysis.

Background: Spinal cord ischemia (SCI) is one of the most devastating complications of thoracic endovascular aortic repair (TEVAR). Prophylactic cerebrospinal fluid drainage (CSFD) has been shown to decrease the risk of SCI in open thoracic aortic procedures; however, its utility in TEVAR remains uncertain. This systematic review and meta-analysis aim to determine the role of prophylactic CSFD in preventing SCI in TEVAR. Methods: A literature search of five databases was performed and all studies published before September 2022 that reported SCI rates in TEVAR patients undergoing prophylactic CSFD were included. A random effects meta-analysis of means or proportions was performed for single-arm data. Odds ratios (ORs) with 95% confidence intervals (CIs) were reported for comparisons between groups. Results: A total of 4,793 patients undergoing TEVAR from 40 studies were included. The mean age was 68.8 years and 70.9% of patients were male. The overall SCI rate was 3.5%, with a 1.3% rate of immediate SCI and a 1.9% rate of delayed SCI. There were no significant differences in SCI rates between prophylactic CSFD patients and non-drained patients. Routine CSFD did not have a significant impact on SCI rates compared to non-drained patients. There was an increased rate of transient SCI with selective CSFD compared to non-drained patients (OR 2.08; 95% CI: 1.06-4.08; P=0.03). The most common drain-related complication was spinal headache (4.3%). The major complication rate was 1.6%, of which epidural or spinal hematoma (0.9%) was the most common, followed by intracranial or subdural hemorrhage (0.8%) and paraparesis or paraplegia (0.8%). Conclusions: This study found no significant difference in SCI rates between prophylactic CSFD patients and their non-drained counterparts. CSFD is associated with a small but non-negligible risk of serious complications. Multi-center randomized controlled trials (RCTs) are warranted to help stratify the risk of both SCI and CSFD-related complications in patients undergoing endovascular aortic procedures.

Permanent Porosity in the Room-Temperature Magnet and Magnonic Material V(TCNE)2.

Materials that simultaneously exhibit permanent porosity and high-temperature magnetic order could lead to advances in fundamental physics and numerous emerging technologies. Herein, we show that the archetypal molecule-based magnet and magnonic material V(TCNE)2 (TCNE = tetracyanoethylene) can be desolvated to generate a room-temperature microporous magnet. The solution-phase reaction of V(CO)6 with TCNE yields V(TCNE)2·0.95CH2Cl2, for which a characteristic temperature of T* = 646 K is estimated from a Bloch fit to variable-temperature magnetization data. Removal of the solvent under reduced pressure affords the activated compound V(TCNE)2, which exhibits a T* value of 590 K and permanent microporosity (Langmuir surface area of 850 m2/g). The porous structure of V(TCNE)2 is accessible to the small gas molecules H2, N2, O2, CO2, ethane, and ethylene. While V(TCNE)2 exhibits thermally activated electron transfer with O2, all the other studied gases engage in physisorption. The T* value of V(TCNE)2 is slightly modulated upon adsorption of H2 (T* = 583 K) or CO2 (T* = 596 K), while it decreases more significantly upon ethylene insertion (T* = 459 K). These results provide an initial demonstration of microporosity in a room-temperature magnet and highlight the possibility of further incorporation of small-molecule guests, potentially even molecular qubits, toward future applications.

Reactive high-spin iron(IV)-oxo sites through dioxygen activation in a metal-organic framework.

In nature, nonheme iron enzymes use dioxygen to generate high-spin iron(IV)=O species for a variety of oxygenation reactions. Although synthetic chemists have long sought to mimic this reactivity, the enzyme-like activation of O2 to form high-spin iron(IV) = O species remains an unrealized goal. Here, we report a metal-organic framework featuring iron(II) sites with a local structure similar to that in α-ketoglutarate-dependent dioxygenases. The framework reacts with O2 at low temperatures to form high-spin iron(IV) = O species that are characterized using in situ diffuse reflectance infrared Fourier transform, in situ and variable-field Mössbauer, Fe Kß x-ray emission, and nuclear resonance vibrational spectroscopies. In the presence of O2, the framework is competent for catalytic oxygenation of cyclohexane and the stoichiometric conversion of ethane to ethanol.

Procedural and clinical outcomes of transcatheter aortic valve replacement in bicuspid aortic valve patients: a systematic review and meta-analysis.

Background: Currently, bicuspid aortic valve (BAV) anatomy remains a relative contraindication for transcatheter aortic valve replacement (TAVR) due to concerns of suboptimal anatomy. However, recent advancements in the field have provided a wealth of promising data and more clinicians are opting for TAVR as an alternative to surgical repair. We aim to review and analyze the available data for TAVR in BAV patients, targeting procedural outcomes, clinical outcomes and mortality with up to two years of follow-up. Methods: A literature search of five databases was performed and all primary studies published between 2002 and 2021 that reported procedural, clinical or mortality outcome data were identified. Following data extraction, a meta-analysis of means or proportions was performed using a random effects model. Heterogeneity was assessed using the I2 statistic. Results: A total of 22 studies with 1,945 BAV patients were identified. The mean age was 74.1 years and 58.8% of patients were male. Device success rates was 87.5%. Moderate to severe paravalvular leak (PVL) was seen in 3.7% of procedures. Clinical outcomes included new permanent pacemaker insertion (PPI) (11.8%), major bleeding (3.5%), major vascular complications (2.5%), stroke (2.3%), acute kidney injury (2.1%) and coronary obstruction (0.1%). Mortality in hospital, at 30-days, one and two years of follow-up were 1.9%, 2.1%, 9.6% and 12.9%, respectively. Conclusions: This assessment of the available data on TAVR for BAV shows promising outcomes and low rates of complications. However, further research is warranted to reduce the heterogeneity of the available data and provide insight into outcomes beyond two years of follow-up.

Correction: Influence of the primary and secondary coordination spheres on nitric oxide adsorption and reactivity in cobalt(ii)-triazolate frameworks.

[This corrects the article DOI: 10.1039/D1SC03994F.].

Influence of the primary and secondary coordination spheres on nitric oxide adsorption and reactivity in cobalt(ii)-triazolate frameworks.

Nitric oxide (NO) is an important signaling molecule in biological systems, and as such, the ability of porous materials to reversibly adsorb NO is of interest for potential medical applications. Although certain metal-organic frameworks are known to bind NO reversibly at coordinatively unsaturated metal sites, the influence of the metal coordination environment on NO adsorption has not been studied in detail. Here, we examine NO adsorption in the frameworks Co2Cl2(bbta) (H2bbta = 1H,5H-benzo(1,2-d:4,5-d')bistriazole) and Co2(OH)2(bbta) using gas adsorption, infrared spectroscopy, powder X-ray diffraction, and magnetometry. At room temperature, NO adsorbs reversibly in Co2Cl2(bbta) without electron transfer, with low temperature data supporting spin-crossover of the NO-bound cobalt(ii) centers of the material. In contrast, adsorption of low pressures of NO in Co2(OH)2(bbta) is accompanied by charge transfer from the cobalt(ii) centers to form a cobalt(iii)-NO- adduct, as supported by diffraction and infrared spectroscopy data. At higher pressures of NO, characterization data indicate additional uptake of the gas and disproportionation of the bound NO to form a cobalt(iii)-nitro (NO2 -) species and N2O gas, a transformation that appears to be facilitated by secondary sphere hydrogen bonding interactions between the bound NO2 - and framework hydroxo groups. These results provide a rare example of reductive NO binding in a cobalt-based metal-organic framework, and they demonstrate that NO uptake can be tuned by changing the primary and secondary coordination environment of the framework metal centers.

Magnetic ordering through itinerant ferromagnetism in a metal-organic framework.

Materials that combine magnetic order with other desirable physical attributes could find transformative applications in spintronics, quantum sensing, low-density magnets and gas separations. Among potential multifunctional magnetic materials, metal-organic frameworks, in particular, bear structures that offer intrinsic porosity, vast chemical and structural programmability, and the tunability of electronic properties. Nevertheless, magnetic order within metal-organic frameworks has generally been limited to low temperatures, owing largely to challenges in creating a strong magnetic exchange. Here we employ the phenomenon of itinerant ferromagnetism to realize magnetic ordering at TC = 225 K in a mixed-valence chromium(II/III) triazolate compound, which represents the highest ferromagnetic ordering temperature yet observed in a metal-organic framework. The itinerant ferromagnetism proceeds through a double-exchange mechanism, which results in a barrierless charge transport below the Curie temperature and a large negative magnetoresistance of 23% at 5 K. These observations suggest applications for double-exchange-based coordination solids in the emergent fields of magnetoelectrics and spintronics.