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A letter to the editor is presented on the case of a man suffering from gelatinous droplike corneal dystrophy.

In order to identify the causative factors of ring abscess, which is the characteristic feature of pseudomonal keratitis, pseudomonal endotoxin, exotoxin A, and elastase were each separately injected into guinea pig cornea. There was no formation of ring abscess. Injection of living Pseudomonas aeruginosa strains IFO3455 and Takamatsu which produce all three molecules, clearly induced ring abscess. In contrast, when heat-killed bacteria strain IFO3455 or living bacteria of the non-elastase-producing strain PA103 were injected, ring abscess was not induced. Furthermore, when living bacteria strain IFO3455 were injected with anti-elastase antibody or a protease inhibitor, ovomacroglobulin, ring abscess formation was significantly inhibited. Histological examination demonstrated that the ring abscess was a dense accumulation and aggregation of polymorphonuclear leukocytes (PMN) with debris of cells and lamellae in the deep stroma at the corneal margins, suggesting prevention of PMN migration to the central lesion. The presence of anti-elastase antibody or a specific elastase inhibitor facilitated PMN migration towards living bacteria strain IFO3455 in an in vitro model. These results indicate that pseudomonal elastase is a necessary but not sufficient factor in the formation of ring abscess in pseudomonal keratitis. [ABSTRACT FROM AUTHOR]

Fe/N/C single-atom catalysts containing Fe-N x sites prepared by pyrolysis are promising cathode materials for fuel cells and metal-air batteries due to their high oxygen reduction reaction (ORR) activities. We have developed iron complexes containing N2- or N3-chelating coordination structures with preorganized aromatic rings in a 1,12-diazatriphenylene framework tethering bromo substituents as precursors to precisely construct Fe-N 4 sites in an Fe/N/C catalyst. One-step pyrolysis of the iron complex with carbon black forms atomically dispersed Fe-N 4 sites without iron aggregates. X-ray absorption spectroscopy (XAS) and electrochemical measurements revealed that the iron complex with N3-coordination is more effectively converted to Fe-N 4 sites catalyzing ORR with a TOF value of 0.21 e site -1  s -1 at 0.8 V vs. RHE. This indicates that the formation of Fe-N 4 sites is controlled by precise tuning of the chemical structure of the iron complex precursor., (© 2021 Wiley-VCH GmbH.)

Heavy atom-containing molecules cause a photoreaction by a direct S 0  → T n transition. Therefore, even in a hypervalent iodine compound with a benzene ring as the main skeleton, the photoreaction proceeds under 365-400 nm wavelength light, where UV-visible spectra are not observed by usual measurement method. Some studies, however, report hypervalent iodine compounds that strongly absorb visible light. Herein, we report the synthesis of two visible light-absorbing hypervalent iodines and their photooxidation properties under visible light irradiation. We also demonstrated that the S 0  → T n transition causes the photoreaction to proceed under wavelengths in the blue and green light region.

Pyrolytically prepared iron and nitrogen codoped carbon (Fe/N/C) catalysts are promising nonprecious metal electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell applications. Fabrication of the Fe/N/C catalysts with Fe-N x active sites having precise structures is now required. We developed a strategy for thermally controlled construction of the Fe-N x structure in Fe/N/C catalysts by applying a bottom-up synthetic methodology based on a N-doped graphene nanoribbon (N-GNR). The preorganized aromatic rings within the precursors assist graphitization during generation of the N-GNR structure with iron-coordinating sites. The Fe/N/C catalyst prepared from the N-GNR precursor, iron ion, and the carbon support Vulcan XC-72R provides a high onset potential of 0.88 V (vs reversible hydrogen electrode (RHE)) and promotes efficient four-electron ORR. X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) studies reveal that the N-GNR precursor induces the formation of iron-coordinating nitrogen species during pyrolysis. The details of the graphitization process of the precursor were further investigated by analyzing the precursors pyrolyzed at various temperatures using MgO particles as a sacrificial template, with the results indicating that the graphitized structure was obtained at 700 °C. The preorganized N-GNR precursors and its pyrolysis conditions for graphitization are found to be important factors for generation of the Fe-N x active sites along with the N-GNR structure in high-performance Fe/N/C catalysts for the ORR.

Benzophenone has an S 0 → S 1 absorption band at 365 nm. However, the rarely reported S 0 → T n transition occurs upon irradiation at longer wavelengths. Herein, we employed benzophenone as a catalyst and exploited its S 0 → T n transition in C(sp 3 )-H alkynylations with hypervalent iodine reagents. The selective benzophenone excitation prevented alkynylating reagent decomposition, enabling the reaction to proceed under mild conditions. The reaction mechanism was investigated by spectroscopic and computational studies.

According to the Grotthuss-Draper law, light must be absorbed by a substrate to initiate a photoreaction. There have been several reports, however, on the promotion of photoreactions using hypervalent iodine during irradiation with light from a non-absorbing region. This contradiction gave rise to a mystery regarding photoreactions involving hypervalent iodine. We demonstrated that the photoactivation of hypervalent iodine with light from the apparently non-absorbing region proceeds via a direct S 0 →T n transition, which has been considered a forbidden process. Spectroscopic, computational, and synthetic experimental results support this conclusion. Moreover, the photoactivation mode could be extended to monovalent iodine and bromine, as well as bismuth(III)-containing molecules, providing new possibilities for studying photoreactions that involve heavy-atom-containing molecules., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The cyclohexene moiety of the tricyclic 6,7-diaryl-tetrahydro-6 H-benzo[ c]chromene core of palodesangrens could be assembled in a biomimetic and step-economical fashion by the Diels-Alder reaction between the electron-rich ( E)-1,3-butadienylarenes as the diene and the electron-deficient chalcones as the dienophile. During the reduction of ketone to the corresponding alcohol by LiAlH 4 , the mixture of endo and exo isomers underwent a novel diastereoconvergent LiAlH 4 -mediated isomerization to install the desired stereochemistry at C10a. Subsequent pyran ring closure under acidic conditions installed the stereochemistry at the remaining C6. Overall, the tricyclic core of palodesangrens could be prepared in three steps and up to 38% yield.

Purpose: A case of corneal lactoferrin amyloidosis secondary to trichiasis is reported., Case: A 30-year-old male suffered from trichiasis with an elevated gray whitish lesion just under the center of the cornea in his right eye. The lesion had an irregular surface., Method: We excised the corneal lesion, and studied the excised corneal lesion morphologically., Result: The deposit observed just under the corneal epithelial layer was positive for Congo red staining, and showed dichroism under polarizing microscopy. The deposit also showed a immunoreactivity against anti-human lactoferrin antibody., Conclusion: The morphological study proved that the deposits under the corneal lesion were derived from lactoferrin. Long term injury of the corneal surface by trichiasis may lead to the deposition and structural changes of lactoferrin originating from tears.