Facile Synthesis of CoOOH Nanorings over Reduced Graphene Oxide and Their Application in the Reduction of p-Nitrophenol

A facile and one-step route has been employed for the synthesis of highly uniform CoOOH nanorings assembled on the surface of reduced graphene oxide (CoOOH/rGO nanocomposite). The physicochemical properties of the obtained CoOOH/rGO nanocomposite were characterized using X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ physical adsorption (BET) and X-ray photoelectron spectroscopy (XPS). The TEM and SEM results confirmed that CoOOH nanorings (edge length ∼ 95 nm) were uniformly decorated on reduced graphene oxide nanosheets using the simple precipitation–oxidation–reduction method. When used as a catalyst for the reduction of p-nitrophenol to p-aminophenol in the presence of excess NaBH₄, the resulting CoOOH/rGO nanocomposite exhibited good activity and stability. When the initial concentration of p-nitrophenol was 1.25 × 10⁻⁴ mol·L⁻¹, p-nitrophenol could be fully reduced within 3.25 min at room temperature. The apparent rate constant was estimated to be 1.77 min⁻¹, which is higher than that of pure CoOOH nanorings. Moreover, p-nitrophenol could still be completely reduced within 6 min in the fifth successive cycle. The superior catalytic performance of the nanocomposite is attributed to the synergistic effect between the highly dispersed CoOOH nanorings and the unique surface properties of the reduced graphene oxide nanosheets, which greatly increased the concentration of p-nitrophenol near CoOOH nanorings on reduced graphene oxide surface and improved the local electron density at the interface.     

~(60)Co照射对大鼠十二指肠内分泌细胞数的影响

观察~(60)钴γ线800rad全身照射后一天内大鼠十二指肠亲银、嗜银细胞的改变,发现照后一天内两种细胞都逐渐减少,亲银细胞数减少的速率比嗜银细胞快。随着细胞数的减少,亲银、嗜银细胞的颗粒亦相对减少,着色变淡。     

Anatomical and electrophysiological study of multitransmitter neuron R14 of Aplysia

This study provides detailed information on the Aplysia neuron R14, including its endogenous electrical activity and extensive axonal projections to a variety of vascular and vascular-related tissues. With the aid of intracellular recording techniques, R14 was found to display in vitro variable spontaneous patterns of silent, beating, or bursting activity. Electrophysiological tracing and intracellular cobalt staining revealed the peripheral processes and target tissues of R14. The white-colored axons of R14 exit the parietovisceral ganglion in the genito-pericardial, spermathecal, branchial, and vulvar nerves. These processes extended 20 mm or more into peripheral tissues: the pericardial wall and lumen, digestive gland sheath, aortae, arteries, and veins. R14 axons also project to the right bag cell cluster. Its extensive axonal projections to tissues associated with the cardiovascular system verify physiological studies that show that R14 plays a role in cardiovascular regulation. This neuron appears to have a wide influence over several aspects of circulation in contrast to individual neurons of the R3-13 group, each of which projects to limited numbers of vascular and vascular-related tissues. R14 also uniquely innervates digestive tissues, thus suggesting that it may act as a nexus between influences on digestive and renal physiology such as ion/water regulation, in addition to modulating cardiovascular homeostasis.     

Retinotopic and chronotopic organization of goldfish retinal ganglion cell axons throughout the optic nerve

The organization of the retinal ganglion cell (RGC) axons within the goldfish optic nerve head and optic nerve was established by labeling select groups of axons either autoradiographically or with cobaltous lysine. In the optic nerve head, the axons are organized eccentrically with respect to their time of development. Axons of older RGCs are located dorsally and those of younger RGCs are located ventrally. The retinal sectors map across the rostrocaudal axis of the optic nerve head, resulting in four dorsoventrally oriented columns that contain, from rostral to caudal, the axons of ventronasal, dorsonasal, dorsotemporal, and ventrotemporal RGCs. Thus, the optic nerve head is organized into orthogonally oriented laminae. One dimension maps the age of the axons and the other maps the retinal sector of the axons' origin. The optic nerve is organized virtually in the same fashion as the optic nerve head. However, glial septa that invade the optic nerve severely distort, but do not eliminate, the columnar organization of the retinal sectors. These septa deflect many RGC axons and disrupt nearest-neighbor relationships. The distortions produced by the glial septa include folding of the columns and distortion of the chronological lamination. However, the glial septa do not extend into the optic foramen. Therefore, a virtually undistorted columnar organization reappears in the optic foramen. Several roles for the glial septa are discussed.     

硬质合金粉尘接触对人体头发、全血钴含量的影响

目的 探讨接触硬质合金粉尘对人体头发、全血钴含量的影响。方法 采集接触组与对照组头发及全血样品，处理后用AAS无火焰法分析钴含量。结果 接触组头发钴含量明显高于对照组（P＜0．001），而全血钴含量与对照组比较无显著性差异（P＞0．05）。接触组男、女性头发钴含量与全血钴含量均呈显著负相关（P＜0．05）。结论 硬质合金粉尘接触可导致人体头发钴含量显著增高，但对人体全血钴含量影响不大。     

Conditions for detecting the mutagenicity of divalent metals in Salmonella typhimurium.

The mutagenesis of metals in bacteria, as reported in the literature, can best be described as inconsistent. We report that cobalt chloride (Co++), ferrous sulfate (Fe++), manganese sulfate (Mn++), cadmium chloride (Cd++), and zinc chloride (Zn++) could be reproducibly detected as mutagens in Salmonella strain TA97 when preincubation exposures were made in sterile, distilled, deionized water, or in Hepes buffer in NaCl2/KCl2, rather than the standard sodium phosphate buffer. Co++ was also mutagenic under standard preincubation conditions. The individual components of Vogel-Bonner medium, i.e., potassium and ammonium phosphate, citrate, and magnesium sulfate, inhibit mutagenesis by these metals. The phosphates and the citrate probably inhibit by chelating the metals, while data are presented to suggest that Mg++ inhibition of metal mutagenesis is due to competitive inhibition for active transport via the magnesium active transport system in Salmonella. The chelator, diethyldithiocarbamate, inhibited the mutagenicity of Co++, Fe++, Zn++, and Mn++, but enhanced the mutagenicity of Cd++. The results presented show that divalent metals can be detected as mutagens in Salmonella, and that their lack of detection as mutagens is not due to an inherent insensitivity of Salmonella but to their interaction with media components and/or passive and active transport processes.     

氯化钴对体外培养的视网膜色素上皮细胞VEGF表达的影响

目的探讨人视网膜色素上皮（RPE）细胞体外纯化培养方法和观察氯化钴（CoCl2）对RPE细胞VEGF表达的影响。方法采用酶辅助的显微分离法分离培养人RPE细胞并用细胞角蛋白和S-100免疫组织化学鉴定，用100μmol／L CoCl2 10％胎牛血清的DMEM培养RPE 30h，用免疫印迹方法测量其VEGF蛋白表达水平。结果酶辅助的显微分离法可体外纯化培养RPE细胞，用细胞角蛋白和S-100免疫组织化学染色均呈阳性。100μmol／L CoCl2作用30h后RPE细胞VEGF表达水平可提高2倍。结论通过Hu氏酶辅助的显微分离法，获得了RPE细胞的纯化培养；CoCl2可明显诱导RPE细胞VEGF表达上调。     

Input-output relationships of identified buccal neurones involved in feeding control in Aplysia

A group of about 28 neurones located in the lateral portion of the caudal face of Aplysia buccal ganglion and projecting into the cerebro-buccal connective were identified by retrograde cobalt staining, and designated as L neurones. It was found that the L neurones did not establish synaptic relations with the known buccal neurones, which are mainly involved in the production of the consummatory phase of feeding, nor with several cerebral neurones tested, including the well-known serotonin giant cell. Neither did they show responses to stimulation of the nerves directed to the buccal mass. On the other hand, the L neurones showed depolarizing responses, with the possible addition of a weak, slower hyperpolarizing phase, to stimulation of the ipsi- and contralateral oesophageal nerves, which innervate the portion of the gut posterior to the buccal mass. These findings, together with several properties of the oesophageal nerve input, suggest that one function of the L cells is to transmit information about gut regions posterior to the buccal mass towards the cerebral ganglia, and that they may mediate the inhibitory influence which in Aplysia is known to be exerted upon feeding by the presence of bulk in the anterior gut. The L neurones showed synaptic responses - consisting mainly or exclusively of depolarizations - to stimulation of the cerebro-buccal connectives. Besides this, large, tonic EPSPs, which often occurred in the 'spontaneous' activity of the L neurones, were found to be generated by spikes that travelled in the cerebro-buccal connective towards the buccal ganglion.(ABSTRACT TRUNCATED AT 250 WORDS)