Singlet Oxygen Generation and Photoinduced Charge Separation of Tetra Polyethyleneglycol Functionalized Zinc Phthalocyanine-Fullerene Dyad

Utilization of polyethyleneglycol （PEG） functionalized zinc phthalocyanine, （PEG）4ZnPc in （i） singlet oxygen generation, and （ii） in building energy harvesting donor-acceptor systems using fullerene, C60 as an acceptor via the well-known metal-ligand axial coordination approach is reported. The （PEG）4ZnPe was found to be capable of producing singlet oxygen with a quantum yield, ooa of 0.77 in toluene, a value higher than that obtained for pristine （t-bu）4ZnPc （φ△=0.54） carrying no PEG groups, revealing its usefulness in photodynamic therapy applications. Spectroscopic studies revealed efficient binding of phenylimidazole functionalized fullerene, C60 Im with l ： 1 stoichiometry to （PEG）4ZnPc. Binding constant K for the formation of （PEG）4ZnPc：ImC60 dyad was found to be 6 × 103 M 1 revealing moderate stability. Geometric and electronic studies of the dyad was arrived by B3LYP/3-21G（＊） method. The HOMO level was found to be on zinc phthalocyanine entity while the LUMO level was found to be on the C60 entity suggesting formation of （PEG）4ZnPc＊＋：ImC60＊ charge separated state during the process of electron transfer reaction. Redox studies on the （PEG）4ZnPc：ImC60 dyad enabled accurate determination of the oxidation and reduction potentials of the donor-acceptor system, and to evaluate free-energy changes associated for the charge separation process. Kinetics of photoinduced charge separation and recombination in the （PEG）4ZnPc：ImC60 dyad was investigated using femtosecond transient absorption studies. Relatively long-lived charge separated states were confirmed for the dyad suggesting their potential usefulness in energy harvesting applications.

Double-sided friction stir welding of Nitronic-40 stainless steel for application in tokamak devices

Nitrogen containing austenitic stainless steels(N-ASS)are widely utilized to fabricate various structural components in tokamak type fusion reactors owing to their suitable mechanical and functional proper-ties.These components are exposed to a range of temperatures(4-500 K)and interact closely with the magnetic fields that are used to control and contain the plasma within the tokamak systems.Nitronic-40(N40)or XM-11 stainless steel is one such N-ASS used for fabricating structural components in the mag-netic and vacuum vessel systems in tokamak devices.Fabrication of most of the larger components in the magnetic and vacuum vessel systems typically involves some type of fusion-based welding process.This study presents a double-sided friction stir welding(FSW)approach as an alternative to fusion welding processes to join 12 mm thick N40 plates to obtain joints with a low fraction ofδferrite(a detrimen-tal ferromagnetic phase),high joint efficiency,no sensitization and loss of hardness in the heat affected zone,and minimal nitrogen desorption from the weld nugget.The double-sided FSW approach yielded superior weldments when compared to similar joints accomplished by fusion welding for application in tokamak devices.

Elimination of extraordinarily high cracking susceptibility of aluminum alloy fabricated by laser powder bed fusion

Using the calculation of phase diagrams approach and Scheil solidification modeling,the Al-2.5Mg-1.0Ni-0.4Sc-0.1Zr alloy was designed,intentionally with an extraordinarily high cracking susceptibility,making it prime for solidification cracking during laser powder bed fusion.This study demonstrates the ability to mitigate even the most extreme solidification cracking tendencies in aluminum alloys with only minor alloying additions of Sc and Zr,0.5 wt.%max.Furthermore,by employing a simple direct ageing heat treatment,good tensile mechanical properties were observed with a yield strength of 308 MPa,an ultimate tensile strength of 390 MPa,and a total elongation of 11%.