Covalent connections between metal-organic frameworks and polymers including covalent organic frameworks.

Hybrid composite materials combining metal-organic frameworks (MOFs) and polymers have emerged as a versatile platform for a broad range of applications. The crystalline, porous nature of MOFs and the flexibility and processability of polymers are synergistically integrated in MOF-polymer composite materials. Covalent bonds, which form between two distinct materials, have been extensively studied as a means of creating strong molecular connections to facilitate the dispersion of "hard" MOF particles in "soft" polymers. Numerous organic transformations have been applied to post-synthetically connect MOFs with polymeric species, resulting in a variety of covalently connected MOF-polymer systems with unique properties that are dependent on the characteristics of the MOFs, polymers, and connection modes. In this review, we provide a comprehensive overview of the development and strategies involved in preparing covalently connected MOFs and polymers, including recently developed MOF-covalent organic framework composites. The covalent bonds, grafting strategies, types of MOFs, and polymer backbones are summarized and categorized, along with their respective applications. We highlight how this knowledge can serve as a basis for preparing macromolecular composites with advanced functionality.

The Changes in Epidemiology of Imipenem-Resistant Acinetobacter baumannii Bacteremia in a Pediatric Intensive Care Unit for 17 Years.

BACKGROUND: Acinetobacter baumannii infections cause high morbidity and mortality in intensive care unit (ICU) patients. However, there are limited data on the changes of long-term epidemiology of imipenem resistance in A. baumannii bacteremia among pediatric ICU (PICU) patients. METHODS: A retrospective review was performed on patients with A. baumannii bacteremia in PICU of a tertiary teaching hospital from 2000 to 2016. Antimicrobial susceptibility tests, multilocus sequence typing (MLST), and polymerase chain reaction for antimicrobial resistance genes were performed for available isolates. RESULTS: A. baumannii bacteremia occurred in 27 patients; imipenem-sensitive A. baumannii (ISAB, n = 10, 37%) and imipenem-resistant A. baumannii (IRAB, n = 17, 63%). There was a clear shift in the antibiogram of A. baumannii during the study period. From 2000 to 2003, all isolates were ISAB (n = 6). From 2005 to 2008, both IRAB (n = 5) and ISAB (n = 4) were isolated. However, from 2009, all isolates were IRAB (n = 12). Ten isolates were available for additional test and confirmed as IRAB. MLST analysis showed that among 10 isolates, sequence type 138 was predominant (n = 7). All 10 isolates were positive for OXA-23-like and OXA-51-like carbapenemase. Of 27 bacteremia patients, 11 were male (41%), the median age at bacteremia onset was 5.2 years (range, 0-18.6 years). In 33% (9/27) of patients, A. baumannii was isolated from tracheal aspirate prior to development of bacteremia (median, 8 days; range, 5-124 days). The overall case-fatality rate was 63% (17/27) within 28 days. There was no statistical difference in the case fatality rate between ISAB and IRAB groups (50% vs. 71%; P = 0.422). CONCLUSION: IRAB bacteremia causes serious threat in patients in PICU. Proactive infection control measures and antimicrobial stewardship are crucial for managing IRAB infection in PICU.

Controlled Two-Dimensional Alignment of Metal-Organic Frameworks in Polymer Films.

Controlling the alignment of metal-organic framework (MOF) particles is valueable for fully exploiting the anisotropic properties and porous structure of these materials. Herein, we propose a simple, one-step method that can control the two-dimensional (2D) alignment of MOF particles over large areas. Orientational control is achieved without consideration of the underlying lattice parameters or the need for particle surface modification, but instead was achieved by selection of the casting solvent on a water surface. Two distinct types of MOF particles, a hexagonal bifrustum morphology of MIL-96 and an octahedral morphology of the UiO-66 family were aligned and captured in a polydimethylsiloxane (PDMS) matrix using this approach. This work provides opportunities for studying and utilizing the anisotropic properties of MOFs in thin film applications.

Specific Isotope-Responsive Breathing Transition in Flexible Metal-Organic Frameworks.

An isotope-selective responsive system based on molecular recognition in porous materials has potential for the storage and purification of isotopic mixtures but is considered unachievable because of the almost identical physicochemical properties of the isotopes. Herein, a unique isotope-responsive breathing transition of the flexible metal-organic framework (MOF), MIL-53(Al), which can selectively recognize and respond to only D2 molecules through a secondary breathing transition, is reported. This novel phenomenon is examined using in situ neutron diffraction experiments under the same conditions for H2 and D2 sorption experiments. This work can guide the development of a novel isotope-selective recognition system and provide opportunities to fabricate flexible MOF systems for energy-efficient purification of the isotopic mixture.

Coordinated Molecule-Modulated Magnetic Phase with Metamagnetism in Metal-Organic Frameworks.

Most well-known metal-organic frameworks (MOFs) possessing the magnetic Ni2O2(CO2)2 chains, called Ni-MOF-74, have been investigated with regard to magnetic properties at open-metal sites. We present the modulation of their magnetic phase and metamagnetism via imidazole molecule coordination.

Selective Hydrogen Isotope Separation via Breathing Transition in MIL-53(Al).

Breathing of MIL-53(Al), a flexible metal-organic framework (MOF), leads to dynamic changes as narrow pore (np) transitions to large pore (lp). During the flexible and reversible transition, the pore apertures are continuously adjusted, thus providing the tremendous opportunity to separate mixtures of similar-sized and similar-shaped molecules that require precise pore tuning. Herein, for the first time, we report a strategy for effectively separating hydrogen isotopes through the dynamic pore change during the breathing of MIL-53(Al), a representative of flexible MOFs. The experiment shows that the selectivity for D2 over H2 is strongly related to the state of the pore structure of MIL-53(Al). The highest selectivity (SD2/H2 = 13.6 at 40 K) was obtained by optimizing the exposure temperature, pressure, and time to systematically tune the pore state of MIL-53(Al).

Exploiting Diffusion Barrier and Chemical Affinity of Metal-Organic Frameworks for Efficient Hydrogen Isotope Separation.

Deuterium plays a pivotal role in industrial and scientific research, and is irreplaceable for various applications such as isotope tracing, neutron moderation, and neutron scattering. In addition, deuterium is a key energy source for fusion reactions. Thus, the isolation of deuterium from a physico-chemically almost identical isotopic mixture is a seminal challenge in modern separation technology. However, current commercial approaches suffer from extremely low separation efficiency (i.e., cryogenic distillation, selectivity of 1.5 at 24 K), requiring a cost-effective and large-scale separation technique. Herein, we report a highly effective hydrogen isotope separation system based on metal-organic frameworks (MOFs) having the highest reported separation factor as high as ∼26 at 77 K by maximizing synergistic effects of the chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS). For this purpose, the MOF-74 system having high hydrogen adsorption enthalpies due to strong open metal sites is chosen for CAQS functionality, and imidazole molecules (IM) are employed to the system for enhancing the KQS effect. To the best of our knowledge, this work is not only the first attempt to implement two quantum sieving effects, KQS and CAQS, in one system, but also provides experimental validation of the utility of this system for practical industrial usage by isolating high-purity D2 through direct selective separation studies using 1:1 D2/H2 mixtures.

Proteomics of rice and Cochliobolus miyabeanus fungal interaction: insight into proteins at intracellular and extracellular spaces.

Necrotrophic fungal pathogen Cochliobolus miyabeanus causes brown spot disease in rice leaves upon infection, resulting in critical rice yield loss. To better understand the rice-C. miyabeanus interaction, we employed proteomic approaches to establish differential proteomes of total and secreted proteins from the inoculated leaves. The 2DE approach after PEG-fractionation of total proteins coupled with MS (MALDI-TOF/TOF and nESI-LC-MS/MS) analyses led to identification of 49 unique proteins out of 63 differential spots. SDS-PAGE in combination with nESI-LC-MS/MS shotgun approach was applied to identify secreted proteins in the leaf apoplast upon infection and resulted in cataloging of 501 unique proteins, of which 470 and 31 proteins were secreted from rice and C. miyabeanus, respectively. Proteins mapped onto metabolic pathways implied their reprogramming upon infection. The enzymes involved in Calvin cycle and glycolysis decreased in their protein abundance, whereas enzymes in the TCA cycle, amino acids, and ethylene biosynthesis increased. Differential proteomes also generated distribution of identified proteins in the intracellular and extracellular spaces, providing a better insight into defense responses of proteins in rice against C. miyabeanus. Established proteome of the rice-C. miyabeanus interaction serves not only as a good resource for the scientific community but also highlights its significance from biological aspects.

Epidemiological and Genetic Characterization of Coxsackievirus A6-Associated Hand, Foot, and Mouth Disease in Gwangju, South Korea, in 2022.

Coxsackievirus A6 (CV-A6) has emerged as the predominant causative agent of hand, foot, and mouth disease (HFMD) in young children. Since the declaration of coronavirus disease 2019 (COVID-19) as a global pandemic, the incidence of infectious diseases, including HFMD, has decreased markedly. When social mitigation was relaxed during the COVID-19 pandemic in 2022, the re-emergence of HFMD was observed in Gwangju, South Korea, and seasonal characteristics of the disease appeared to have changed. To investigate the molecular characteristics of enterovirus (EV) associated with HFMD during 2022, 277 specimens were collected. Children aged younger than 5 years accounted for the majority of affected individuals. EV detection and genotyping were performed using real-time RT-PCR and nested RT-PCR followed by sequence analysis. The EV detection rate was found to be 82.3%, and the main genotype identified was CV-A6. Sixteen CV-A6 samples were selected for whole genome sequencing. According to phylogenetic analysis, all CV-A6 strains from this study belonged to the sub-genotype D3 clade based on VP1 sequences. Analysis of 3D polymerase phylogeny showed that only the recombinant RF-A group was identified. In conclusion, circulating EV types should be continuously monitored to understand pathogen emergence and evolution during the post-pandemic era.

Microfluidic approach toward continuous and ultrafast synthesis of metal-organic framework crystals and hetero structures in confined microdroplets.

Herein, we report a novel nanoliter droplet-based microfluidic strategy for continuous and ultrafast synthesis of metal-organic framework (MOF) crystals and MOF heterostructures. Representative MOF structures, such as HKUST-1, MOF-5, IRMOF-3, and UiO-66, were synthesized within a few minutes via solvothermal reactions with substantially faster kinetics in comparison to the conventional batch processes. The approach was successfully extended to the preparation of a demanding Ru3BTC2 structure that requires high-pressure hydrothermal synthesis conditions. Finally, three different types of core-shell MOF composites, i.e., Co3BTC2@Ni3BTC2, MOF-5@diCH3-MOF-5, and Fe3O4@ZIF-8, were synthesized by exploiting a unique two-step integrated microfluidic synthesis scheme in a continuous-flow mode. The synthesized MOF crystals were characterized by X-ray diffraction, scanning electron microscopy, and BET surface area measurements. In comparison with bare MOF-5, MOF-5@diCH3-MOF-5 showed enhanced structural stability in the presence of moisture, and the catalytic performance of Fe3O4@ZIF-8 was examined using Knoevenagel condensation as a probe reaction. The microfluidic strategy allowed continuous fabrication of high-quality MOF crystals and composites exhibiting distinct morphological characteristics in a time-efficient manner and represents a viable alternative to the time-consuming and multistep MOF synthesis processes.

Extracting optical modes of organic light-emitting diodes using quasi-periodic WO3 nanoislands.

Quasi-periodic WO(3) nanoislands are introduced to extract two optical modes in organic light-emitting diodes. The nano-scaled and size-tunable WO(3) islands were fabricated by use of wet-etching with self-aggregated Ag mask. The improvement of light extraction efficiency originates to the recovery of light losses which are surface plasmon mode and waveguide mode. As a result, external quantum efficiency and power efficiency were increased. No changes in emission spectrum and CIE color coordinates with WO(3) nanoislands at various observation angles are desirable if this device is to be utilized in optical system. Furthermore, cost-effective fabrication makes it possible to adopt this system in large area fabrication.

Synthesis of Triazole and Tetrazole-Functionalized Zr-Based Metal-Organic Frameworks Through Post-Synthetic Ligand Exchange.

Metal-organic frameworks (MOFs) are a class of porous materials that are formed through coordination bonds between metal clusters and organic ligands. Given their coordinative nature, the organic ligands and strut framework can be readily removed from the MOF and/or exchanged with other coordinative molecules. By introducing target ligands to MOF-containing solutions, functionalized MOFs can be obtained with new chemical tags via a process called post-synthetic ligand exchange (PSE). PSE is a straightforward and practical approach that enables the preparation of a wide range of MOFs with new chemical tags via a solid-solution equilibrium process. Furthermore, PSE can be performed at room temperature, allowing the incorporation of thermally unstable ligands into MOFs. In this work, we demonstrate the practicality of PSE by using heterocyclic triazole- and tetrazole-containing ligands to functionalize a Zr-based MOF (UiO-66; UiO = University of Oslo). After digestion, the functionalized MOFs are characterized via various techniques, including powder X-ray diffraction and nuclear magnetic resonance spectroscopy.

Effect and Safety of Pressure Sensor-equipped Handpiece in Phacoemulsification System.

PURPOSE: To evaluate the effect of the Active Sentry handpiece of the Centurion Vision System compared to the Centurion Ozil handpiece for phacoemulsification in cataract surgery. METHODS: A retrospective study was conducted on 281 patients (449 eyes) who underwent cataract surgery between August 2020 and June 2021. Preoperative measurements, intraoperative parameters, complication rate, and postoperative outcomes were compared between the Active Sentry handpiece and the Centurion Ozil handpiece groups. Additionally, the parameters were compared in different cataract severity groups and multiple predictive factors for the number of active surge mitigation (ASM) actuations were assessed with the Active Sentry handpiece. RESULTS: There were 198 eyes in the Active Sentry group and 251 eyes in the Centurion Ozil group. There were no statistically significant differences between the two groups, as the cumulative dissipated energy in the Active Sentry and Centurion Ozil groups were 8.32 ± 7.74 and 7.87 ± 9.25 µJ, respectively (p = 0.576). Total surgery time, ultrasound usage time, aspiration time, amount of fluid aspirated, postoperative corrected distant visual acuity, and postoperative decrease in corneal endothelial cell density were comparable between the two groups. The significant contributors to the number of ASM actuations were age, preoperative corrected distant visual acuity, axial length, and total ultrasound time. CONCLUSIONS: There was no clear advantage of the Active Sentry handpiece compared to the Centurion Ozil handpiece. ASM actuation increases with age, poor visual acuity before surgery, short axial length, and prolonged ultrasound usage time. It is expected that in more severe and high-risk cataract surgery, the Active Sentry handpiece functions more effectively, possibly affecting the safety and prognosis.

Surface plasmon-waveguide hybrid polymer light-emitting devices using hexagonal Ag dots.

We investigated surface plasmon-waveguide hybrid resonances for enhancement of light emission in polymer light-emitting diodes (PLEDs). Hybrid waveguide-plasmon resonances in the visible range for waveguide mode and near IR range for surface plasmons were observed by incorporation of hexagonal Ag dot arrays. Considerable overlap between the emission wavelength of the PLEDs and the waveguide mode by an Ag dot array with a lattice constant of 500 nm was observed. Because of enhanced light extraction by Bragg scattering of waveguide modes, photoluminescence (PL) and electroluminescence (EL) were increased by 70% and 50%, respectively.

Lifetime risk and age of onset distributions of psychiatric disorders: analysis of national sample survey in South Korea.

BACKGROUND: The present study represents the first attempt at examining variation across Korean cohorts with respect to lifetime risk of DSM-IV psychiatric disorders. AIMS: To present data on lifetime prevalence and projected lifetime risk, as well as age of onset (AOO) and demographic correlates of DSM-IV psychiatric disorders as assessed in the nationwide survey of a representative sample of Korean adults. METHOD: The survey was based on a multistage area probability sample of non-institutionalized Koreans aged 18-64 years. The Korean version of the Composite International Diagnostic Interview 2.1 (K-CIDI 2.1) was administered by lay interviewers. RESULTS: Lifetime prevalence of any disorder was 24.6%. Alcohol abuse (9.2%), alcohol dependence (7.0%), major depressive disorder (5.6%), specific phobia (3.8%), and GAD (1.6%) were the most common disorders. The median AOO was earliest for anxiety disorders (age 29), latest for mood disorders (age 47), and intermediate for alcohol use disorders (age 31). Compared to observed lifetime prevalence (24.6%), 35.0% of Koreans will eventually experience one of these disorders. Further, half of the population who present with a psychiatric disorder do so by the age of 32 and younger cohorts are at greater risk for most disorders. CONCLUSIONS: About one-third of the Korean adult population will meet the criteria for a DSM-IV psychiatric disorder at some time during their life. The median age of onset varies from disorder to disorder and younger cohorts appear to be at greater risk for most disorders.

Post-synthetic ligand cyclization in metal-organic frameworks through functional group connection with regioisomerism.

A covalent connection between two orthogonal functional groups (-NH2 and -OH) in metal-organic frameworks (MOFs) has been developed. This post-synthetic ligand cyclization (PSLC) was successfully demonstrated to synthesize a benzoxazole-functionalized MOF from a Zr-based UiO-66-2,3-(NH2)(OH) under microwave irradiation. In contrast, the regioisomeric UiO-66-2,5-(NH2)(OH) only produces a non-cyclized formamide-functionalized MOF.

Influence of Mechanical Fatigue at Different States of Charge on Pouch-Type Li-Ion Batteries.

Since flexible devices are being used in various states of charge (SoCs), it is important to investigate SoCs that are durable against external mechanical deformations. In this study, the effects of a mechanical fatigue test under various initial SoCs of batteries were investigated. More specifically, ultrathin pouch-type Li-ion polymer batteries with different initial SoCs were subjected to repeated torsional stress and then galvanostatically cycled 200 times. The cycle performance of the cells after the mechanical test was compared to investigate the effect of the initial SoCs. Electrochemical impedance spectroscopy was employed to analyze the interfacial resistance changes of the anode and cathode in the cycled cells. When the initial SoC was at 70% before mechanical deformation, both electrodes well maintained their initial state during the mechanical fatigue test and the cell capacity was well retained during the cycling test. This indicates that the cells could well endure mechanical fatigue stress when both electrodes had moderate lithiation states. With initial SoCs at 0% and 100%, the batteries subjected to the mechanical test exhibited relatively drastic capacity fading. This indicates that the cells are vulnerable to mechanical fatigue stress when both electrodes have high lithiation states. Furthermore, it is noted that the stress accumulated inside the batteries caused by mechanical fatigue can act as an accelerated degradation factor during cycling.

Relationship between physical activity and mental health in a nationwide sample of Korean adults.

OBJECTIVE: There is widespread recognition of the effect of physical activity on mental health. The authors examined the relationships between physical activity and mental health in a nationwide sample of Korean adults. METHODS: A total of 6,510 subjects aged 18 to 64 years participated in the study. The short form of the International Physical Activity Questionnaire was used to estimate the level of physical activity. Mental health was assessed using the Composite International Diagnostic Interview, the Epidemiological Studies Depression Scale (CES-D), and the General Health Questionnaire (GHQ). Logistic regression analysis was used to compare the prevalence of CES-D and GHQ cases and psychiatric disorders among the following physical activity categories: inactive, minimally active, and health-enhancing physical activity (HEPA) active. RESULTS: HEPA-active or minimally active subjects were less likely to be classified as "depressed" on the CES-D (≥21) and "psychologically distressed" on the GHQ (≥3) than were physically inactive subjects. HEPA was associated with a significantly decreased 1-year prevalence of major depressive disorder and obsessive-compulsive disorder, and with a significantly increased 1-year prevalence of alcohol abuse, relative to physical inactivity. In addition, HEPA was associated with a significantly increased 1 year prevalence of alcohol abuse, relative to minimal physical activity. Physical inactivity was associated with a significantly increased 1-year prevalence of alcohol dependence, relative to physical inactivity. CONCLUSIONS: The results indicate a negative association between physical activity and depressive and anxiety disorders. A high level of physical activity seems to be associated with alcohol abuse, but a moderate level of physical activity may play a role in preventing alcohol dependence.

Relationships of mental disorders and weight status in the Korean adult population.

The purpose of this study was to evaluate the associations between weight status and mental disorders, including depressive disorder, anxiety disorder and alcohol use disorder. A total of nationally representative 6,510 subjects aged 18-64 yr was interviewed in face-to-face household survey. Response rate was 81.7%. Mental disorders were diagnosed using the Korean version of the Composite International Diagnostic Interview (K-CIDI). The subjects reported their heights and weights. After adjusting for age and gender, the lifetime diagnosis of depressive disorder had a significant association with only the underweight group (odds ratio [OR], 1.68, 95% confidence interval [CI], 1.19-2.38). The association between underweight and depressive disorder was the strongest for subjects with a high education level (OR, 1.75, 95% CI, 1.2-2.56), subjects with a married/cohabiting status (OR, 1.94, 95% CI, 1.17-3.22) and smokers (OR, 2.58, 95% CI, 1.33-4.98). There was no significant association between obesity and depressive disorder in Korea. But there was a significant association between the underweight group and depressive disorder. The relationship between obesity and mental disorder in a Korean population was different from that in a Western population. These results suggest that the differences of traditional cultures and races might have an important effect on the associations between the weight status and mental disorders.

Elucidation of Diffusivity of Hydrogen Isotopes in Flexible MOFs by Quasi-Elastic Neutron Scattering.

Kinetic-quantum-sieving-assisted H2 :D2 separation in flexible porous materials is more effective than the currently used energy-intensive cryogenic distillation and girdle-sulfide processes for isotope separation. It is believed that material flexibility results in a pore-breathing phenomenon under the influence of external stimuli, which helps in adjusting the pore size and gives rise to the optimum quantum-sieving phenomenon at each stage of gas separation. However, only a few studies have investigated kinetic-quantum-sieving-assisted isotope separation using flexible porous materials. In addition, no reports are available on the microscopic observation of isotopic molecular transportation during the separation process under dynamic transition. Here, the experimental observation of a significantly faster diffusion of deuterium than hydrogen in a flexible pore structure, even at high temperatures, through quasi-elastic neutron scattering, is reported. Unlike rigid structures, the extracted diffusion dynamics of hydrogen isotopes within flexible frameworks show that the diffusion difference between the isotopes increases with an increase in temperature. Owing to this unique inverse trend, a new strategy is suggested for achieving higher operating temperatures for efficient isotope separation utilizing a flexible metal-organic framework system.