H2O2 rejuvenation-mediated synthesis of stable mixed-morphology Ag3PO4 photocatalysts.

Ag3PO4 photocatalyst has attracted interest of the scientific community in recent times due to its reported high efficiency for water oxidation and dye degradation. However, Ag3PO4 photo-corrodes if electron accepter such as AgNO3 is not used as scavenger. Synthesis of efficient Ag3PO4 followed by a simple protocol for regeneration of the photocatalyst is therefore a prerequisite for practical application. Herein, we present a facile method for the synthesis of a highly efficient Ag3PO4, whose photocatalytic efficiency was demonstrated using 3 different organic dyes: Methylene Blue (MB), Methyl orange (MO) and Rhodamine B (RhB) organic dyes for degradation tests. Approximately, 19 % of Ag3PO4 is converted to Ag0 after 4.30 hours of continuous UV-Vis irradiation in presence of MB organic dye. We have shown that the Ag/Ag3PO4 composite can be rejuvenated by a simple chemical oxidation step after several cycles of photocatalysis tests. At an optimal pH of 6.5, a mixture of cubic, rhombic dodecahedron, nanosphere and nanocrystals morphologies of the photocatalyst was formed. H2O2 served as the chemical oxidant to re-insert the surface metallic Ag into the Ag3PO4 photocatalyst but also as the agent that can control morphology of the regenerated as-prepared photocatalyst without the need for any other morphology controlling Agent (MCA). Surprisingly, the as- regenerated Ag3PO4 was found to have higher photocatalytic reactivity than the freshly made material and superior at least 17 times in comparison with the conventional Degussa TiO2, and some of TiO2 composites tested in this work

Investigating energy dissipation through nucleon transfer reactions

Nucleon and cluster transfer probabilities have been measured in the collisions of 16,18O, 19F with 204,208Pb, 209Bi for charge stripping channels down to ΔZ = - 3. Strong evidence of correlated nucleon transfer has been observed in particular channels, and neighbouring systems are seen to differ significantly in their behaviour. New measurements were made using an improved ΔE-E telescope. The back-scattered projectilelike fragments were measured in the telescope at θlab = 160.6°, and in combination with monitor detectors at forward angles allowed determination of absolute transfer probabilities. The improved design allows isotopic yields to be measured with greater precision

Evolution of signatures of quasifission in reactions forming curium

Background: Quasifission, a fission-like reaction outcome in which no compound nucleus forms, is an important competitor to fusion in reactions leading to superheavy elements. The precise mechanisms driving the competition between quasifission and fusio

How signatures of quasifission evolve in reactions forming Curium

Quasifission, a fission-like reaction outcome in which no compound nucleus forms, is an important competitor to fusion in reactions used for super-heavy element formation. The precise mechanisms driving the competition between quasifission and fusion are poorly understood. To explore the influence reaction parameters have on quasifission probabilities, an investigation into the evolution of quasifission signatures as a function of entrance channel parameters is required. Using the Australian National University’s 14UD tandem accelerator and CUBE detector for two-body fission studies, measurements were made for a diverse range of reactions forming isotopes of Curium. Observables known to reveal signs of quasifission—namely mass ratio spectra, mass-angle distributions, and angular anisotropies—were extracted. Evidence of quasifission was observed in all reactions, but the observables showing evidence of quasifission were not the same for all reactions. A link between this evolution and reaction timescales will be discusse

Fission cross sections as a probe of fusion dynamics at high angular momentum

Background: Fusion of heavy nuclei requires energy dissipation to trap the system inside the capture barrier. At high angular momentum, the centrifugal potential causes the barrier radius to reduce, which may lead to energy dissipation outside the barrier, affecting the fusion angular momentum distributions and thus the capture cross sections. Purpose: To investigate the sensitivity of fusion-fission cross sections as a probe of fusion dynamics at high angular momentum. Method: Fission of the compound nucleus Yb164 formed by three different fusion reactions, namely, O16+Sm148, Si28+Ba136, and Ca40+Sn124, was measured at four beam energies well above their respective capture barriers. Fission cross sections were extracted from the measured fission fragment angular distributions and compared with model calculations of fusion and subsequent fission. Fusion and evaporation residue cross sections available in the literature for the same or similar reactions were used to guide model calculations and obtain the fusion angular momentum distributions. Results: The measured fission characteristics were found to be consistent with fusion-fission, as expected, justifying the use of the statistical model to calculate fission cross sections for each reaction. Significantly different fission cross-section predictions were obtained from calculations using angular momentum distributions corresponding to different coupling schemes and different diffuseness parameter of the nuclear potential. A large diffuseness parameter (0.65 fm) of the nuclear potential was observed to give the best reproduction of both the experimental fusion as well as fission cross sections. Conclusions: Experimental fission cross sections provide a stringent constraint to the fusion model calculations and thus prove to be a sensitive probe for understanding fusion dynamics at high angular momentum. This is shown in the present work by a simultaneous analysis of the fusion and fission cross sections for systems where fission cross sections form a small fraction of the fusion cross section and where noncompound nuclear processes are not a dominant competing channel. Observations from this work also suggest the requirement of evaporation residue as well as fission cross sections of higher precision than those generally available for drawing quantitative conclusions.The support from Australian Research Council through Grants No. DE140100784, No. DP160101254, No. FL110100098, and No. FT120100760 and support for the HIAF accelerator operations from the Australian Federal Government NCRIS program is gratefully acknowledged

Probing cluster structures through sub-barrier transfer reactions

Multinucleon transfer probabilities and excitation energy distributions have been measured in 16,18O, 19F + 208Pb at energies between 90% - 100% of the Coulomb barrier. A strong 2p2n enhancement is observed for all reactions, though most spectacularly in the 18O induced reaction. Results are interpreted in terms of the Semiclassical model, which seems to suggest α-cluster transfer in all studied systems. The relation to cluster-states in the projectile is discussed, with the experimental results consistent with previous structure studies. Dissipation of energy in the collisions of 18O is compared between different reaction modes, with cluster transfer associated with dissipation over a large number of internal states. Cluster transfer is shown to be a long range dissipation mechanism, which will inform the development of future models to treat these dynamic processes in reactions

Computerized characterization of breast masses on threeâ dimensional ultrasound volumes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134860/1/mp9531.pd