Yes / Emtricitabine (ECB) afforded dimorphic cocrystals (Forms I, II) of benzoic acid (BA), whereas with p-hydroxybenzoic acid (PHBA), p-aminobenzoic acid (PABA) are resulted in as high Z'' cocrystals. Intriguingly, the Z'' of cocrystals are trends from two to fourteen based on the manipulation of functional groups on the para position of BA (where H atom is replaced with that of OH or NH2 group). ECB‒PABA cocrystal consists of six molecules each and two water molecules in the asymmetric unit (Z''=14) with 2D planar sheets represents the rare pharmaceutical cocrystal. The findings suggest that the increment of H bond donor(s) systematically via a suitable coformer are in correspondence with attaining high Z'' cocrystals. Further, solid state NMR spectroscopy in conjunction with single crystal X-ray diffraction are demonstrated as significant tools to enhance the understanding of the number of symmetry independent molecules in the crystalline lattice and provide insights to the mechanistic pathways of crystallization. / Department of Science and Technology (DST) Fund for improvement of S & T Infrastructure (FIST) with grant no. SR/FST/CST-266/2015(c) to PS and VP. AN and VV acknowledge the Government of India under National Overseas Scholarship (2012-13) and High Commission of India, London UK for PhD studentship.

The series of compounds [M(H2O)2(15-crown-5)](NO3)2, M = Mg, Mn, Co, Cu and Zn, has been extended to include two new phases for M = Fe and two new phases for M = Ni. The system [M(H2O)2(15-crown-5)](NO3)2 is remarkable for having many high-Z’ phases (Z’ > 1) with similar packing and for having solid-solid phase transitions through which there is no significant loss of crystallinity. The synthesis of the analogous Ni complex was carried out. Single-crystal X-ray diffraction showed that the coordination of the Ni2+ ion is different from that of the other six M2+ ions in the system [M(H2O)2(15-crown- 5)](NO3)2. High temperature phases with high Z’ (8) were isolated for M = Mg, Fe and Zn. The refinements of such phases are challenging because of the lack of information in the diffraction patterns. Full details of the refinements for these three phases are discussed. Six other Ni(II) complexes consisting of Ni2+, NO3-, 15-crown-5 and different solvents were found when efforts were made to synthesize the compound [Ni(H2O)2(15-crown- 5)](NO3)2. In these chemically different environments, the Ni2+ ions are not coordinated by the 15-crown-5 molecules; rather, one-dimensional H-bonded chains are formed from uncomplexed 15-crown-5 molecules and the Ni(II) complexes. Among these six Ni(II) complexes, the compounds [Ni(H2O)6](NO3)2·(15-crown-5)·H2O, [Ni(H2O)6](NO3)2·(15-crown-5)·2H2O and [Ni(H2O)2(MeCN)(NO3)2]·(15-crown- 5)·MeCN were found to have reversible solid-solid phase transitions between structurally related phases. In all of these transitions, no significant crystal damage was detectable. The two latter systems are unusual because their phase sequences include three transitions and four phases between 90 and 295 K and because of the existence of high-Z’ phases. These high-Z’ phases are best depicted as being intermediate to low- and hightemperature phases. A method based on thermal analyses and X-ray diffraction has been developed for studying such sets of phase transitions.

Massive galaxies evolve through different phases including starburst-dominated and active galactic nuclei (AGN)-dominated phases. These phases are predicted to be prevalent at earlier times (z ∼ 2 − 3). In this thesis I present high-sensitivity observations from the Atacama Large Millimeter/submillimeter Array to investigate mid-J (Jupper = 4 and 5) CO emission in nine Wide-field Infrared Survey Explorer-selected hyperluminous, hot dust-obscured galaxies (Hot DOGs). These sources are thought to represent a transition phase between starburst- and AGN-dominated galaxies at z ≈ 2.5 − 5. All nine sources are detected in continuum and line emission. I conclude that the sources are gas-rich with Mgas ≈ 1010−11 M . Previous far-infrared spectral energy distribution decomposition revealed that six of the sources have significant cold dust components suggesting high star-formation rates (SFR ≈ 2000 − 9000 M  yr−1 ). The molecular gas in the sources is shown to follow roughly the same star-formation trend as a smaller sample of Hot DOGs and other populations of star-forming and quasar-host galaxies at low- and high-redshift. The resolved CO emission line data displays large velocity dispersions (FWHM ≈ 400 − 900 km s−1 ) consistent with other high-z star-forming and quasar-host galaxies. For a subset of the sources, the line data shows disturbed morphologies and velocity gradients possibly consistent with rotation or galaxy interaction. The results from this analysis suggest that the studied sources are heavily dust-obscured quasars undergoing extreme starburst episodes. The estimated gas and dynamical masses of the sources are consistent with other populations of massive galaxies at low- and high-z, indicating that they likely represent a stage in the evolution of massive galaxies. / <p>Presentaiton given over zoom platform during COVID-19 pandemic.</p>

Controlled thermonuclear fusion may become an attractive future electrical power source. The most promising of all fusion machine concepts is called a tokamak. The fuel, a plasma made of deuterium and tritium, must be confined to enable the fusion process. It is also necessary to protect the wall of tokamaks from erosion by the hot plasma. To increase wall lifetime, the high-Z metal tungsten is foreseen as wall material in future fusion devices due to its very high melting point. This thesis focuses on the following consequences of plasma impact on a high-Z wall: (i) erosion, transport and deposition of high-Z wall materials; (ii) fuel retention in tokamak walls; (iii) long term effects of plasma impact on structural machine parts; (iv) dust production in tokamaks. An extensive study of wall components has been conducted with ion beam analysis after the final shutdown of the TEXTOR tokamak. This unique possibility offered by the shutdown combined with a tracer experiment led to the largest study of high-Z metal migration and fuel retention ever conducted. The most important results are:   - transport is greatly affected by drifts and flows in the plasma edge; - stepwise transport along wall surfaces takes place mainly in the toroidal direction; - fuel retention is highest on slightly retracted wall elements; - fuel retention is highly inhomogeneous.   A broad study on structural parts of a tokamak has been conducted on the TEXTOR liner. The plasma impact does neither degrade mechanical properties nor lead to fuel diffusion into the bulk after 26 years of duty time. Peeling deposition layers on the liner retain fuel in the order of 1g and represent a dust source. Only small amounts of dust are found in TEXTOR with overall low deuterium content. Security risks in future fusion devices due to dust explosions or fuel retention in dust are hence of lesser concern. / <p>QC 20170630</p>