Radical-Assisted Formation of Pd Single Atoms or Nanoclusters on Biochar

Supported single atom or nanocluster catalysts have been widely studied due to their excellent catalytic properties. Many methods to prepare such catalysts start with constructing defects on supports, and the main focus is to improve dispersion and stability of the active sites. This paper for the first time reports a radical-assisted method to prepare single atom or nanocluster Pd on a biochar. The char was prepared by pyrolyzing walnut shell at 600°C under N2, and Pd was loaded on the char by impregnating with palladium acetate in toluene under an oxygen-free atmosphere. It is found that there are three types of radicals in the fresh char (F-Char-600), two of them may adsorb/bond with O2 or Pd2+ resulting in decreases in the char's radical concentration. The Pd on F-Char-600 for 24 h impregnation are single atoms (0.1–0.3 nm, 2%) and nanoclusters (0.3–1.2 nm, 98%), which grow larger (0.3–4 nm, 100%) for 84 h impregnation. The Pd on N2 purged O2-adsorbed-char (N-O-Char-600) is much larger in size. The bond between Pd and char is probably C–Pd in F-Char-600 or C–O–Pd in N-O-Char-600.

In situ measurement for tropospheric OH radical by Laser Induced Fluorescence technique during STORM campaign

<p>Hydroxyl (OH) play an essential role in atmospheric chemistry. OH radical is an indicator of atmospheric oxidation and self-purification, which determines the removal of most trace gases in the atmosphere, such as CO, SO<sub>2</sub>, NO<sub>2</sub>, CH<sub>4</sub> and other volatile organic compounds (VOCs). A ground-based system for measurement of tropospheric OH radical by Laser Induced Fluorescence technique (AIOFM-LIF) was developed and integrated into a mobile observation platform for field observation. Ambient air expands through a 0.4 mm nozzle to low pressure. OH radical is irradiated by the 308 nm laser pulse at a repetition rate of 8.5 kHz, accompanying the release fluorescence of the A<sup>2</sup>Σ<sup>+</sup>(v’=0)—X<sup>2</sup>Π<sub>i</sub>(v’’=0) transition at 308 nm with the resultant fluorescence being detected by gated photon counting. The detection sensitivity of AIOFM-LIF system was calibrated by a portable standard OH radical source based on water photolysis-ozone actinometry. Following laboratory and field calibrations to characterise the instrument sensitivity, OH radical detection limits were (1.84±0.26) × 10<sup>5</sup> cm<sup>-3</sup> and (3.69±0.52) × 10<sup>5</sup> cm<sup>-3</sup> at night and noon, respectively. During “A comprehensive STudy of the Ozone foRmation Mechanism in Shenzhen” (STORM) campaign, AIOFM-LIF system was deployed in Shenzhen, China, and OH radical concentration was obtained validly except for the rainy days. Mean diurnal variation of HOx radical concentration was obtained, and the peak was 6.6×10<sup>6</sup> cm<sup>-3</sup> which appeared around 12:00 at noon. A general good agreement of OH radical concentration with j(O<sup>1</sup>D) was observed with a high correlation (R<sup>2</sup> =0.77), which illustrates that photolysis of ozone is an important source of OH radical during this campaign. A box model was applied to simulate the concentrations of OH at this field site, the primary production of OH radical was generally dominated by photolysis of O<sub>3</sub>, HONO, HCHO, while the other production was contributed by calculated species (OVOCs).</p>

Toxicopathological, Cytogenetic Effects of Acetothioamide on Female Albino Mice Reproductive System

AIM: To determine toxicopathological and cytogenetic effects of Acetothioamide (ATA) on the female reproductive system. METHODS: Twenty albino female mice were divided equally into two groups: the first group (control) fed with diet pellet. The second group (treated) were inoculated intraperitoneally with a single dose of ATA (100 mg/kg Bw) for 15 days. All mice were sacrificed at the end of the experiment and blood was collected for evaluation of (FSH and LH), serum peroxy nitrate radical concentration. Cytogenetic analysis (chromosomal aberration, micronuclei, mitotic index and blast index) and the histopathological examination on ovary and uterus were done. RESULTS: ATA causes significant reduction (p < 0.0001) for FSH, LH and serum peroxy nitrate radical concentration among treated females. Oophoritis, pyometria, thrombosis and endometrial hyperplasia with granulomatous reaction were reported among treated females mainly in uterus tissue and ovary. CONCLUSION: ATA causes significant reduction for FSH, LH and serum peroxy nitrate concentration among treated females. Oophoritis, pyometria, thrombosis and endometrial hyperplasia with granulomatous reaction were the main pathological changes in uterus tissue and ovary among treated females.

In situ formation of 1D nanostructures from ceria nanoparticle dispersions by liquid cell TEM irradiation

Deliberate electron irradiation of cerium oxide nanoparticles in water is used to trigger chemical reactions in a liquid cell transmission electron microscope. Formation of nanorods and nanoneedles is observed starting from predominantly octahedral shape nanoparticles. Detailed morphologies found include free-standing needles, needles connected to specific octahedral ceria facets and star-shaped multi-needle patterns. It is found that rod-axis orientations and crystallographic directions are aligned. It is suggested that high ion and radical concentration of radiolysed water dissolves layers of the original CeO2 particles which re-arrange as needles in the direction of energetically preferred facets.