Bioinspired microenvironment modulation of metal-organic framework-based catalysts for selective methane oxidation.

Inspiration from natural enzymes enabling creationary catalyst design is appealing yet remains extremely challenging for selective methane (CH4) oxidation. This study presents the construction of a biomimetic catalyst platform for CH4 oxidation, which is constructed by incorporating Fe-porphyrin into a robust metal-organic framework, UiO-66, furnished with saturated monocarboxylic fatty acid bearing different long alkyl chains. The catalysts demonstrate the high efficiency in the CH4 to methanol (CH3OH) conversion at 50 °C. Moreover, the selectivity to CH3OH can be effectively regulated and promoted through a fine-tuned microenvironment by hydrophobic modification around the Fe-porphyrin. The long-chain fatty acids anchored on the Zr-oxo cluster of UiO-66 can not only tune the electronic state of the Fe sites to improve CH4 adsorption, but also restrict the amount of H2O2 around the Fe sites to reduce the overoxidation. This behavior resembles the microenvironment regulation in methane monooxygenase, resulting in high CH3OH selectivity.

Hydrogen Bonding Regulated Flexibility and Disorder in Hydrazone-Linked Covalent Organic Frameworks.

Covalent organic framework (COF) chemistry is experiencing unprecedented development in recent decades. The current studies on COF chemistry are mainly focused on the discovery of novel covalent linkages, new topological structures, synthetic methodologies, and potential applications. However, despite the fact that noncovalent interactions are ubiquitous in COF chemistry, relatively little attention has been given to the role of noncovalent bonds on COF structures and their properties. In this work, a series of hydrazone-linked COFs involving noncovalent hydrogen bonds have been constructed, where the hydrogen-bonding interaction plays critical roles in the COF crystallinity and structures. The regulation of structural flexibility, the reversible transition between order and disorder, and the variety of host-guest interactions have been demonstrated in succession for the first time in COFs. The results obtained by the hydrogen-bonding-regulated strategy may also be extendable to other noncovalent interactions, such as π-π interactions, metal coordination interactions, Lewis acid-base interactions, etc. These findings will inspire future developments in the design, synthesis, structural regulation, and applications of COFs by manipulating noncovalent interactions.

Validation of the predictive accuracy of "clinical + morphology nomogram" for the rebleeding risk of ruptured intracranial aneurysms after admission.

BACKGROUND: Rebleeding can cause a catastrophic outcome after aneurysmal subarachnoid hemorrhage. A clinical + morphology nomogram was promoted in our previous study to assist in discriminating the rupture intracranial aneurysms (RIAs) with a high risk of rebleeding. The aim of this study was to validate the predictive accuracy of this nomogram model. METHOD: The patients with RIAs in two medical centers from December 2020 to September 2021 were retrospectively reviewed, whose clinical and morphological parameters were collected. The Cox regression model was employed to identify the risk factors related to rebleeding after their admission. The predicting accuracy of clinical + morphological nomogram, ELAPSS score and PHASES score was compared based on the area under the curves (AUCs). RESULTS: One hundred thirty-eight patients with RIAs were finally included in this study, 20 of whom suffering from rebleeding after admission. Hypertension (hazard ratio (HR), 2.54; a confidence interval of 95% (CI), 1.01-6.40; P = 0.047), bifurcation (HR, 3.88; 95% CI, 1.29-11.66; P = 0.016), and AR (HR, 2.68; 95% CI, 1.63-4.41; P < 0.001) were demonstrated through Cox regression analysis as the independent risk factors for rebleeding after admission. The clinical + morphological nomogram had the highest predicting accuracy (AUC, 0.939, P < 0.01), followed by the bifurcation (AUC, 0.735, P = 0.001), AR (AUC, 0.666, P = 0.018), and ELAPSS score (AUC, 0.682, P = 0.009). Hypertension (AUC, 0.693, P = 0.080) or PHASES score (AUC, 0.577, P = 0.244) could not be used to predict the risk of rebleeding after admission. The calibration curve for the probability of rebleeding showed a good agreement between the prediction through clinical + morphological nomogram and actual observation. CONCLUSION: Hypertension, bifurcation site, and AR were independent risk factors related to the rebleeding of RIAs after admission. The clinical + morphological nomogram could help doctors to identify the high-risk RIAs with a high predictive accuracy.

A General Strategy to Immobilize Single-Atom Catalysts in Metal-Organic Frameworks for Enhanced Photocatalysis.

Single-atom catalysts (SACs) are witnessing rapid development due to their high activity and selectivity toward diverse reactions. However, it remains a grand challenge in the general synthesis of SACs, particularly featuring an identical chemical microenvironment and on the same support. Herein, a universal synthetic protocol is developed to immobilize SACs in metal-organic frameworks (MOFs). Significantly, by means of SnO2 as a mediator or adaptor, not only different single-atom metal sites, such as Pt, Cu, and Ni, etc., can be installed, but also the MOF supports can be changed (for example, UiO-66-NH2 , PCN-222, and DUT-67) to afford M1 /SnO2 /MOF architecture. Taking UiO-66-NH2 as a representative, the Pt1 /SnO2 /MOF exhibits approximately five times higher activity toward photocatalytic H2 production than the corresponding Pt nanoparticles (≈2.5 nm) stabilized by SnO2 /UiO-66-NH2 . Remarkably, despite featuring identical parameters in the chemical microenvironment and support in M1 /SnO2 /UiO-66-NH2 , the Pt1 catalyst possesses a hydrogen evolution rate of 2167 µmol g-1 h-1 , superior to the Cu1 and Ni1 counterparts, which is attributed to the differentiated hydrogen binding free energies, as supported by density-functional theory (DFT) calculations. This is thought to be the first report on a universal approach toward the stabilization of SACs with identical chemical microenvironment on an identical support.

Advantages of using a prophylactic epidural closed drain and non-watertight dura suture in a craniotomy near the "parietal site".

BACKGROUND: In neurosurgery, the necessity of having a drainage tube is controversial. Subgaleal fluid collection (SFC) often occurs, especially in a craniotomy near the "parietal site".This study aimed to reassess the benefit of using a prophylactic epidural drainage (ED) and non-watertight dura suture in a craniotomy near the parietal site. METHODS: A retrospective review was conducted on 63 consecutive patients who underwent a craniotomy near the parietal site. The patients were divided into two groups according to different period. The deal group received ED and a non-watertight dura suture (drain group, DG), the control group that did not (non-drain group, NDG). Complications and patient recovery were evaluated and analysed. RESULTS: Three patients (11.5%, 26) in DG and 20 patients (54.1%, 37) in NDG presented with SFC (p < 0.05). One patient (3.8%) in DG and three patients (8.1%) in NDG presented with subdural tensile hydrops (STH) (p > 0.05). Six developed an infection in NDG (four intracranial infections, one abscess, one pulmonary infection), while none in DG (p > 0.05) developed infection. Three (11.5%) cases in DG and one (2.7%) case in NDG had muscle strength that improved postoperatively (p > 0.05). Fifteen (57.7%) in DG and 14 (37.8%) in NDG had epileptic seizures less frequently postoperatively (p < 0.05). The average temperature (37.4 °C vs 37.6 °C, p > 0.05), the maximum temperature (37.9 °C vs 38.1 °C, p > 0.05) on 3 PODs, the postoperative hospital stay day (7.5 days vs 8.0 days, p > 0.05), and the postoperative medicine fee (¥29762.0 vs ¥28321.0, p > 0.05) were analysed. CONCLUSION: In patients who undergo a craniotomy near the parietal site, the prophylactic use of ED and a non-watertight dura suture helps reduce SFC, infection, and control epilepsy.

Iron-naphthalenedicarboxylic acid gels and their high efficiency in removing arsenic(v).

Metal-organic gels (MOGs) of three-dimensional (3D) networks comprising nanosheets of ∼30 nm thickness and square-micrometer in size were easily produced via coordination interactions of iron (Fe(3+)) and 1,4-naphthalenedicarboxylic acid (NDC). Such MOGs exhibit ultrahigh removal of arsenic(v) in water, with the adsorption capacity of 144 mg g(-1), dramatically superior to those of the recently reported Fe-based inorganic and organic adsorbents.

Hydrogelation and Crystallization of Sodium Deoxycholate Controlled by Organic Acids.

The gelation and crystallization behavior of a biological surfactant, sodium deoxycholate (NaDC), mixed with l-taric acid (L-TA) in water is described in detail. With the variation of molar ratio of L-TA to NaDC (r = n(L-TA)/n(NaDC)) and total concentration of the mixtures, the transition from sol to gel was observed. SEM images showed that the density of nanofibers gradually increases over the sol-gel transition. The microstructures of the hydrogels are three-dimensional networks of densely packed nanofibers with lengths extending to several micrometers. One week after preparation, regular crystallized nanospheres formed along the length of the nanofibers, and it was typical among the transparent hydrogels induced by organic acids with pKa1 value <3.4. Small-angle X-ray diffraction demonstrated differences in the molecular packing between transparent and turbid gels, indicating a variable hydrogen bond mode between NaDC molecules.