Topographic organization across foveal visual areas in macaques.

Introduction: While the fovea on the retina covers only a small region of the visual field, a significant portion of the visual cortex is dedicated to processing information from the fovea being a critical center for object recognition, motion control, and visually guided attention. Despite its importance, prior functional imaging studies in awake monkeys often focused on the parafoveal visual field, potentially leading to inaccuracies in understanding the brain structure underlying function. Methods: In this study, our aim is to unveil the neuronal connectivity and topography in the foveal visual cortex in comparison to the parafoveal visual cortex. Using four different types of retrograde tracers, we selectively injected them into the striate cortex (V1) or V4, encompassing the regions between the fovea and parafovea. Results: V1 and V4 exhibited intense mutual connectivity in the foveal visual field, in contrast to the parafoveal visual field, possibly due to the absence of V3 in the foveal visual field. While previous live brain imaging studies failed to reveal retinotopy in the foveal visual fields, our results indicate that the foveal visual fields have continuous topographic connectivity across V1 through V4, as well as the parafoveal visual fields. Although a simple extension of the retinotopic isoeccentricity maps from V1 to V4 has been suggested from previous fMRI studies, our study demonstrated that V3 and V4 possess gradually smaller topographic maps compared to V1 and V2. Feedback projections to foveal V1 primarily originate from the infragranular layers of foveal V2 and V4, while feedforward projections to foveal V4 arise from both supragranular and infragranular layers of foveal V1 and V2, consistent with previous findings in the parafoveal visual fields. Discussion: This study provides valuable insights into the connectivity of the foveal visual cortex, which was ambiguous in previous imaging studies.

The synthesis of CB[8]/ZnO composites materials with enhanced photocatalytic activities.

Enhancing the separation of hole-electron pairs is one of the valid pathway to enhance the photocatalytic degradation performance of semiconductors. In this work, cucurbit[8]uril/zinc oxide (CB[8]/ZnO) composites were prepared. The structure, morphology, surface elements and optical properties of the composite are characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoemission spectroscopy, thermogravimetric analysis, and specific surface area measurements. In the photocatalytic degradation of 500 mg/L reactive brilliant red X-3B and 400 mg/L reactive yellow X-RG solutions, the rate constant of the CB[8]/ZnO composite is six times that of pure ZnO. A possible photocatalytic degradation mechanism is proposed. Zn2+ ions chelate with the carbonyl group of CB[8] on the surface of CB[8]/ZnO. Under ultraviolet-visible light irradiation, the generated holes of ZnO are transferred to and trapped on the CB[8] units to facilitate the separation of electron-hole pairs, improving the photocatalytic performance of this system.

Efficient removal of heavy metal ions and organic dyes with cucurbit [8] uril-functionalized chitosan.

The development of a high-efficiency adsorption material is important for the simultaneous elimination of heavy metal ions and organic pollutants from wastewater. In the present work, a novel material was synthesized by grafting functionalized cucurbit [8] uril (CB[8]) onto chitosan (CS) chains via a CNC covalent bond (CB[8]-CS). This as-prepared material presented an unprecedented adsorption capacity. The maximum adsorption capacities (qm) were 1622.7 mg/g, 1172.7 mg/g, 1361.9 mg/g and 873.6 mg/g for the adsorption of reactive orange 5 (RO5), acidic blue 25 (AB25), reactive yellow 145 (RY145) and Pb2+ ions, respectively, which are far higher than the reported data. The simultaneous co-adsorption of dye and a heavy metal ion was tested with a mixed solution of 200 mg/L RO5 dye and Pb2+ ion, and the removal rates were 97% and 70% for RO5 and Pb2+, respectively. The adsorption mechanism was explored by means of the IR spectrum and the UV-vis diffuse reflection spectrum (DRS) together with theoretical calculations. The adsorption of dyes was mainly driven by the strong interaction between dye molecules and the hydrophobic cavity of CB[8], and the Pb2+ adsorption was mainly driven by the coordination of Pb2+ with the carbonyl of the CB[8] port and the amino group of chitosan. The ultrahigh adsorption capacity allows the use of CB[8]-CS as potential adsorbent for the simultaneous removal of heavy metal ions and organic dyes from aqueous solution.