Simulation of Changes in Tensile Strain by Airbag Impact on Eyes After Trabeculectomy by Using Finite Element Analysis.

Purpose: We studied the kinetic phenomenon of an airbag impact on eyes after trabeculectomy using finite element analysis (FEA), a computerized method for predicting how an object reacts to real-world physical effects and showing whether an object will break, to sequentially determine the responses at various airbag deployment velocities. Methods: A human eye model was used in the simulations using the FEA program PAM-GENERISTM (Nihon ESI, Tokyo, Japan). A half-thickness incised scleral flap was created on the limbus and the strength of its adhesion to the outer sclera was set at 30%, 50%, and 100%. The airbag was set to hit the surface of the post-trabeculectomy eye at various velocities in two directions: perpendicular to the corneal center or perpendicular to the scleral flap (30° gaze-down position), at initial velocities of 20, 30, 40, 50, and 60 m/s. Results: When the airbag impacted at 20 m/s or 30 m/s, the strain on the cornea and sclera did not reach the mechanical threshold and globe rupture was not observed. Scleral flap lacerations were observed at 40 m/s or more in any eye position, and scleral rupture extending posteriorly from the scleral flap edge and rupture of the scleral flap resulting from extension of the corneal laceration through limbal damage were observed. Even in the case of 100% scleral flap adhesion strength, scleral flap rupture occurred at 50 m/s impact velocity in the 30° gaze-down position, whereas in eyes with 30% or 50% scleral flap adhesion strength, scleral rupture was observed at an impact velocity of 40 m/s or more in both eye positions. Conclusion: An airbag impact of ≥40 m/s might induce scleral flap rupture, indicating that current airbags may induce globe rupture in the eyes after trabeculectomy. The considerable damage caused by an airbag on the eyes of short-stature patients with glaucoma who have undergone trabeculectomy might indicate the necessity of ocular protection to avoid permanent eye damage.

Fabrication of Self-Expanding Metal-Organic Cages Using a Ring-Openable Ligand.

Metal-organic cages (MOCs), which are formed via coordination-driven assembly, are being extensively developed for various applications owing to the utility of their accessible molecular-sized cavity. While MOC structures are uniquely and precisely predetermined by the metal coordination number and ligand configuration, tailoring MOCs to further modulate the size, shape, and chemical environment of the cavities has become intensively studied for a more efficient and adaptive molecular binding. Herein, we report self-expanding MOCs that exhibit remarkable structural variations in cage size and flexibility while maintaining their topology. A cyclic ligand with an oligomeric chain tethering the two benzene rings of stilbene was designed and mixed with RhII ions to obtain the parent MOCs. These MOCs were successfully transformed into expanded MOCs via the selective cleavage of the double bond in stilbene. The expanded MOCs could effectively trap multidentate N-donor molecules in their enlarged cavity, in contrast to the original MOCs with a narrow cavity. As the direct synthesis of expanded MOCs is impractical because of the entropically disfavored structures, self-expansion using ring-openable ligands is a promising approach that allows precision engineering and the production of functional MOCs that would otherwise be inaccessible.

An approach to MOFaxanes by threading ultralong polymers through metal-organic framework microcrystals.

Mechanically interlocked architecture has inspired the fabrication of numerous molecular systems, such as rotaxanes, catenanes, molecular knots, and their polymeric analogues. However, to date, the studies in this field have only focused on the molecular-scale integrity and topology of its unique penetrating structure. Thus, the topological material design of such architectures has not been fully explored from the nano- to the macroscopic scale. Here, we propose a supramolecular interlocked system, MOFaxane, comprised of long chain molecules penetrating a microcrystal of metal-organic framework (MOF). In this study, we describe the synthesis of polypseudoMOFaxane that is one of the MOFaxane family. This has a polythreaded structure in which multiple polymer chains thread a single MOF microcrystal, forming a topological network in the bulk state. The topological crosslinking architecture is obtained by simply mixing polymers and MOFs, and displays characteristics distinct from those of conventional polyrotaxane materials, including suppression of unthreading reactions.

Accurate deep learning model using semi-supervised learning and Noisy Student for cervical cancer screening in low magnification images.

Deep learning technology has been used in the medical field to produce devices for clinical practice. Deep learning methods in cytology offer the potential to enhance cancer screening while also providing quantitative, objective, and highly reproducible testing. However, constructing high-accuracy deep learning models necessitates a significant amount of manually labeled data, which takes time. To address this issue, we used the Noisy Student Training technique to create a binary classification deep learning model for cervical cytology screening, which reduces the quantity of labeled data necessary. We used 140 whole-slide images from liquid-based cytology specimens, 50 of which were low-grade squamous intraepithelial lesions, 50 were high-grade squamous intraepithelial lesions, and 40 were negative samples. We extracted 56,996 images from the slides and then used them to train and test the model. We trained the EfficientNet using 2,600 manually labeled images to generate additional pseudo labels for the unlabeled data and then self-trained it within a student-teacher framework. Based on the presence or absence of abnormal cells, the created model was used to classify the images as normal or abnormal. The Grad-CAM approach was used to visualize the image components that contributed to the classification. The model achieved an area under the curve of 0.908, accuracy of 0.873, and F1-score of 0.833 with our test data. We also explored the optimal confidence threshold score and optimal augmentation approaches for low-magnification images. Our model efficiently classified normal and abnormal images at low magnification with high reliability, making it a promising screening tool for cervical cytology.

Thermal Transformation of Polyacrylonitrile Accelerated by the Formation of Ultrathin Nanosheets in a Metal-Organic Framework.

In this study, polyacrylonitrile (PAN) nanosheets with unimolecular thickness were successfully synthesized by cross-linking polymerization in the 2D nanospaces of a metal-organic framework. In contrast to 1D and 3D analogues, crystallization could be inhibited by the topological constraint of the ultrathin 2D network structure, allowing for an efficient thermal transformation reaction of PAN. The amorphous nature of the PAN nanosheets led to an increase in the access of oxygen molecules to the polymer chains, facilitating the thermal dehydroaromatization reactions to yield a ladder polymer structure with a highly extended conjugated system. Notably, further carbonization of this ladder polymer afforded graphitic carbon with a highly ordered structure because of the well-defined precursor structure.

Fabrication of Double-Stranded Vinyl Polymers Mediated by Coordination Nanochannels.

Although double-stranded structures are commonly found in biopolymers, a general and versatile methodology for fabricating double-stranded synthetic polymers has not yet been developed. Here, we report a new approach for synthesizing double-stranded polymers composed of polystyrene and poly(methyl methacrylate). We conducted crosslinking radical polymerization inside a metal-organic framework (MOF), which had one-dimensional channels with diameters similar to the thickness of two polymer chains. Effective spatial constraint within the MOF pores facilitated highly regulated crosslinking reactions between two polymer chains with extended conformations. Remarkably, the obtained double-stranded polymers were soluble in many organic solvents, even at a high crosslinking ratio (20%), unlike conventional crosslinked polymers. Notably, this stable duplex topology, which was inaccessible using previous methods, endowed the double-stranded vinyl polymers with unusual properties in the solution and bulk states. By designing the properties of the MOF nanochannels, the proposed technique can contribute to the development of a wide range of synthetic polymer duplexes.

Topological entrapment of macromolecules during the formation of metal-organic framework.

Here we present our preliminary results on a novel approach to encapsulate large guest molecules in nanoporous materials, metal-organic frameworks (MOFs), via a newly discovered in situ crystal formation. This method has exciting prospects not only in the design of new organic/inorganic hybrids but also in capturing and separating molecules that are significantly larger than the actual pore size of the host MOF.

Toughening and stabilizing MOF crystals via polymeric guest inclusion.

Improving the mechanical properties and stability of metal-organic frameworks (MOFs) is of significant interest due to their practical applications. Herein, we tune the mechanical properties of MOFs by filling the MOF pores with polymer chains. The mechanical properties reflect the filling rate, molecular weight, and inherent flexibility of the polymeric guests, imparting MOFs with improved resilience and toughness against mechanical pressures.

Mixed Metal-Organic Framework Stationary Phases for Liquid Chromatography.

Strategic design of the stationary phase in liquid chromatography (LC) is crucial for modern separation science. Herein, a design approach using mixed metal-organic frameworks (MOFs) as tunable LC stationary phases is proposed. Three MOFs with an isostructural pillared-layer structure are employed, with pore sizes tuned by the systematic design of the constituent ligands, using 1,4-benzenedicarboxylate (bdc), 1,4-naphthalenedicarboxylate (ndc), and 9,10-anthracenedicarboxylate (adc). Packed columns filled with the MOFs and their mixed-particle/solid-solution stationary phases are prepared and examined for the retention capability of polyethylene glycol (PEG) in LC. While the MOF-packed columns filled with binary mixtures of different MOF particles provide good control of the retention with respect to the particle mixing ratio, the columns filled with mixed-linker solid-solution MOFs show a significant multicomponent effect on the retention behavior. Specifically, mixed-linker solid-solution MOFs consisting of bdc/ndc binary ligands are found to show a strong retention that surpasses even their parent MOFs, namely, pure bdc- and ndc-MOF stationary phases. The retention behavior on the MOF-packed columns is explained by the specific nanostructures of the solid-solution MOFs, which affects the balance between substrate affinity and adsorption kinetics into the MOF pores, dictating the total retention capability. The results provide an extra dimension for stationary phase design using MOFs as a promising recognition medium for LC.

[Comparison of two cases of type 2 autoimmune pancreatitis].

We describe two cases of type 2 autoimmune pancreatitis (AIP). A 39-year-old man presented to our hospital with complaints of epigastric and back pain. Pancreatic enzyme levels were elevated, but serum levels of immunoglobulins G and G4 (IgG and IgG4) were normal. Computed tomography (CT) showed diffuse pancreatic enlargement, and endoscopic retrograde pancreatography revealed diffuse narrowing of the pancreatic duct. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) revealed granulocytic epithelial lesions and very few IgG4-positive cells. Colonoscopy revealed ulcerative colitis. Type 2 AIP was diagnosed, and 5-aminosalicylic acid (5-ASA) and prednisolone were administered. The clinical course has since been favorable, and the prednisolone dose is currently being reduced. A 47-year-old woman presented to our hospital with complaints of bloody stools. Colonoscopy revealed ulcerative colitis. CT depicted diffuse pancreatic enlargement with a capsule-like rim. Pancreatic enzyme levels were elevated, but serum levels of IgG and IgG4 were normal. On magnetic resonance cholangiopancreatography, the pancreatic duct could not be delineated. No pathological findings of type 2 AIP were obtained on EUS-FNA. Type 2 AIP was suspected, and 5-ASA and steroid enemas were administered. To date, recurrence has not been observed, and 5-ASA management continues. The two cases differed with regard to sex of patient, clinical course, pathological findings, and treatment.

Hybridization of Synthetic Humins with a Metal-Organic Framework for Precious Metal Recovery and Reuse.

The number of synthetic strategies used to functionalize MOFs with polymers is rapidly growing; this stems from the knowledge that non-native polymeric guests can significantly boost MOF performance in a number of desirable applications. The current work presents a scalable and solid-state method for MOF/polymer composite production. This simple method constitutes mixing a MOF powder, namely, Fe-BTC (BTC = 1,3,5-benzenetricarboxylate), with a biomass-derived solid monomer, 5-hydroxymethylfurfural (HMF), and subsequently heating the solids; the latter promotes both solid-state diffusion of HMF into the MOF and the formation of polymeric humin species with a high density of accessible hydroxyl functionality within the MOF pore. The resulting composite, Fe-BTC/humin, was found to selectively extract Ag+ ions from laundry wastewater. Subsequent reduction of the Ag+ species yields a novel catalyst, Fe-BTC/humin/Ag, that is able to drive the organic transformation of cinnamaldehyde in a highly selective manner. Moreover, the catalyst exhibited recyclability up to five cycles, which is in contrast to the Fe-BTC/Ag catalyst without the humin-based polymer. It is envisioned that MOF/polymer composites that are able to selectively extract precious metals from liquid waste streams can be used for the future production of sustainable catalysts; this work was aimed at demonstrating a proof of concept in this regard. Moreover, this study brings more understanding of the impact that MOFs can have on polymer functionalities. Understanding the polymer structure and how it can be manipulated will help us realize the high degree of future potential of this distinct class of composite materials.

Revisiting molecular adsorption: unconventional uptake of polymer chains from solution into sub-nanoporous media.

Adsorption of polymers from the solution phase has been extensively studied to cope with many demands not only for separation technologies, but also for the development of coatings, adhesives, and biocompatible materials. Most studies hitherto focus on adsorption on flat surfaces and mesoporous adsorbents with open frameworks, plausibly because of the preconceived notion that it is unlikely for polymers to enter a pore with a diameter that is smaller than the gyration diameter of the polymer in solution; therefore, sub-nanoporous materials are rarely considered as a polymer adsorption medium. Here we report that polyethylene glycols (PEGs) are adsorbed into sub-nanometer one-dimensional (1D) pores of metal-organic frameworks (MOFs) from various solvents. Isothermal adsorption experiments reveal a unique solvent dependence, which is explained by the balance between polymer solvation propensity for each solvent and enthalpic contributions that compensate for potential entropic losses from uncoiling upon pore admission. In addition, adsorption kinetics identify a peculiar molecular weight (MW) dependence. While short PEGs are adsorbed faster than long ones in single-component adsorption experiments, the opposite trend was observed in double-component competitive experiments. A two-step insertion process consisting of (1) an enthalpy-driven recognition step followed by (2) diffusion regulated infiltration in the restricted 1D channels explains the intriguing selectivity of polymer uptake. Furthermore, liquid chromatography using the MOFs as the stationary phase resulted in significant PEG retention that depends on the MW and temperature. This study provides further insights into the mechanism and thermodynamics behind the present polymer adsorption system, rendering it as a promising method for polymer analysis and separation.

Metal-Organic Frameworks as Versatile Media for Polymer Adsorption and Separation.

Molecular recognition is of paramount importance for modern chemical processes and has now been achieved for small molecules using well-established host-guest chemistry and adsorption-science principles. In contrast, technologies for recognizing polymer structure are relatively undeveloped. Conventional polymer separation methods, which are mostly limited in practice to size-exclusion chromatography and reprecipitation, find it difficult to recognize minute structural differences in polymer structures as such small structural alterations barely influence the polymer characteristics, including molecular size, polarity, and solubility. Therefore, most of the polymeric products being used today contain mixtures of polymers with different structures as it is challenging to completely control polymer structures during synthesis even with state-of-the-art substitution and polymerization techniques. In this context, development of novel techniques that can resolve the challenges of polymer recognition and separation is in great demand, as these techniques hold the promise of a new paradigm in polymer synthesis, impacting not only materials chemistry but also analytical and biological chemistry.In biological systems, precise recognition and translation of base monomer sequences of mRNA are achieved by threading them through small ribosome tunnels. This principle of introducing polymers into nanosized channels can possibly help us design powerful polymer recognition and separation technologies using metal-organic frameworks (MOFs) as ideal and highly designable recognition media. MOFs are porous materials comprising organic ligands and metal ions and have been extensively studied as porous beds for gas separation and storage. Recently, we found that MOFs can accommodate large polymeric chains in their nanopores. Polymer chains can spontaneously infiltrate MOFs from neat molten and solution phases by threading their terminals into MOF nanochannels. Polymer structures can be recognized and differentiated due to such insertion processes, resulting in the selective adsorption of polymers on MOFs. This enables the precise recognition of the polymer terminus structure, resulting in the perfect separation of a variety of terminal-functionalized polymers that are otherwise difficult to separate by conventional polymer separation methods. Furthermore, the MOFs can recognize polymer shapes, thus enabling the large-scale separation of high purity cyclic polymers from the complex crude mixtures of linear polymers, which are used as precursor materials in common cyclization reactions. In solution-phase adsorption, many factors, including molecular weight, terminal groups, polymer shape, polymer-MOF interaction, and coexisting solvent molecules, influence the selective adsorption behavior; this yields a new liquid chromatography-based polymer separation technology using an MOF as the stationary phase. MOF-packed columns, in which a novel separation mode based on polymer insertion into the MOF operates under a dynamic insertion/rejection equilibrium at the liquid/solid interface, exhibited excellent polymer separation capability. The polymer recognition principle described in this study thus has a high probability for realizing previously unfeasible polymer separations based on monomer composition and sequences, stereoregularity, regioregularity, helicity, and block sequences in synthetic polymers and biomacromolecules.

Chiral Induction in Buckminsterfullerene Using a Metal-Organic Framework.

Chiral induction is an emerging topic of interest in various areas of chemistry because of its relationship to the elusive mechanism of spontaneous symmetry breaking in nature. Buckminsterfullerene (C60 ) with the shape of a highly symmetric truncated icosahedron has rarely been referred for chiral induction due to the difficult symmetry breaking. In this work, we demonstrate that a chiral metal-organic framework (MOF) can provide a key field for chiral induction. C60 could be incorporated into the chiral nanochannels of the MOF using an in situ self-assembly strategy. The circular dichroism spectra of the resulting nanocomposites showed an intense chiral signal in the absorption region of C60 . Experimental and theoretical studies showed that this unprecedented chiral induction of C60 was attributed to hybridization of the molecular orbitals through a close association with the pore surface of the MOF. Our method can endow highly symmetric achiral compounds with chirality, paving the new way toward fabrication of novel chiral nanomaterials.

Metal-Organic Frameworks for Practical Separation of Cyclic and Linear Polymers.

The purification step in the manufacturing of cyclic polymers is difficult as complete fractionation to eliminate linear impurities requires considerable effort. Here, we report a new polymer separation methodology that uses metal-organic frameworks (MOFs) to discriminate between linear and cyclic polyethylene glycols (PEGs) via selective polymer insertion into the MOF nanopores. Preparation of a MOF-packed column allowed analytical and preparative chromatographic separation of these topologically distinct pairs. In addition, gram-scale PEGs with only cyclic structures were successfully obtained from a crude reaction mixture by using MOF as an adsorbent.

Outcomes of dogs with progressive myelomalacia treated with hemilaminectomy or with extensive hemilaminectomy and durotomy.

OBJECTIVE: To evaluate the ability of extensive hemilaminectomy and durotomy (EHLD) to control progressive myelomalacia (PMM) in dogs. STUDY DESIGN: Retrospective clinical study. ANIMALS: Twenty-eight client owned dogs that underwent EHLD (n = 10) or HL alone (n = 18). METHODS: After diagnosis by MRI, dogs were immediately treated with HL alone or EHLD at the site of intramedullary hyperintensity on T2-weighted (T2W)-MRI. Medical records were retrospectively reviewed. Follow-up data were collected via telephone interviews with the referring veterinarian and a standardized questionnaire. Postoperative survival outcome between groups was compared (log-rank test) by using Cox's proportional hazard analysis with baseline characteristics entered as covariates. RESULTS: The survival rate was higher in the EHLD group (P = .03) compared with the HL-alone group. Eleven of 18 dogs treated with HL survived, while seven of 18 dogs died (median, 5 days after surgery). In the EHLD group, 10 of 10 dogs survived postoperatively. Baseline characteristics were not associated with postoperative survival outcomes. According to multivariate analysis, EHLD was the independent factor associated with an increase in survival rate (P = .0002). CONCLUSION: EHLD durotomy at the intramedullary hyperintense region on T2W-MRI improved the survival rate of dogs with PMM compared with dogs treated with standard HL. CLINICAL SIGNIFICANCE: This study provides evidence that supports treatment with EHLD in dogs with PMM. Additional prospective studies are required.

Unimolecularly thick monosheets of vinyl polymers fabricated in metal-organic frameworks.

Polymers with two-dimensional (2D) network topologies are currently gaining significant attention due to their unique properties that originate from their regulated conformations. However, in contrast to conventional 1D- and 3D-networked macromolecules, the synthesis of such 2D networks provides challenges for polymer chemists because of the nature of the networking polymerisation reaction, which occurs in a spatially random fashion when conventional solution-phase synthesis is performed. Here we report a versatile synthesis of polymeric monosheets with unimolecularly thick networking architectures by exploiting the 2D nanospaces of metal-organic frameworks (MOFs) as reaction templates. Crosslinking radical polymerisation in the 2D nanospaces of pillared-layer-type MOFs affords monosheets of typical vinyl polymers and can be carried out on the gram scale. Remarkably, the prepared polymer monosheets are highly soluble in organic solvents and show atypical thermal and rheological properties that result from their 2D-regulated conformations that cannot be adopted by their 1D or 3D analogues.

Supramolecular Chiral Nanoarchitectonics.

Exploration of molecular functions and material properties based on the control of chirality would be a scientifically elegant approach. Here, the fabrication and function of chiral-featured materials from both chiral and achiral components using a supramolecular nanoarchitectonics concept are discussed. The contents are classified in to three topics: i) chiral nanoarchitectonics of rather general molecular assemblies; ii) chiral nanoarchitectonics of metal-organic frameworks (MOFs); iii) chiral nanoarchitectonics in liquid crystals. MOF structures are based on nanoscopically well-defined coordinations, while mesoscopic orientations of liquid-crystalline phases are often flexibly altered. Discussion on the effects and features in these representative materials systems with totally different natures reveals the universal importance of supramolecular chiral nanoarchitectonics. Amplification of chiral molecular information from molecules to materials-level structures and the creation of chirality from achiral components upon temporal statistic fluctuations are universal, regardless of the nature of the assemblies. These features are thus surely advantageous characteristics for a wide range of applications.

Scalable and Precise Synthesis of Armchair-Edge Graphene Nanoribbon in Metal-Organic Framework.

Graphene nanoribbons (GNRs), narrow and straight-edged stripes of graphene, attract a great deal of attention because of their excellent electronic and magnetic properties. As of yet, there is no fabrication method for GNRs to satisfy both precision at the atomic scale and scalability, which is critical for fundamental research and future technological development. Here, we report a methodology for bulk-scale synthesis of GNRs with atomic precision utilizing a metal-organic framework (MOF). The GNR was synthesized by the polymerization of perylene (PER) or its derivative within the nanochannels of the MOF. Molecular dynamics simulations showed that PER was uniaxially aligned along the nanochannels of the MOF through host-guest interactions, which allowed for regulated growth of the nanoribbons. A series of characterizations of the GNR, including NMR, UV/vis/NIR, and Raman spectroscopy measurements, confirmed the formation of the GNR with well-controlled edge structure and width.