48 research outputs found
Focusing of high energy electron beam using crystal lenses for applications in radiotherapy
The two dominant radiotherapy methods are either simplified in terms of beam
generation and handling, which compromises the energy deposition curve in
tissues (photon therapy), or require extensive accelerator facilities and
complex beam delivery systems to provide a favorable shape of the energy
deposition curve (hadron therapy). The advantages of both of these methods,
such as the low cost of the apparatus, ease of beam generation, and a suitable
shape of the energy deposition curve in tissues, can potentially be achieved by
using a very high-energy electron beam (beam energy in the order of a few
hundreds of MeV) focused on the area of the tumor lesion. However, focusing of
the beam is usually done with the use of quadrupole magnets which makes the
beam delivery system complex and challenging from the engineering point of
view. In this thesis, the feasibility of an alternative solution is explored,
where focusing is performed by a bent silicon crystal with an appropriate shape
of its exit face. Such a crystal lens can be a very light object (mass in the
order of grams), allowing for much simpler beam delivery systems of
radiotherapy facilities. As a result of this feasibility study, a simulation of
a bent silicon crystal with profiled exit was prepared in Geant4. The outcome
obtained from the simulation proved the focusing ability of such profiled
crystal. However, the focusing strength of the crystal is not strong enough.
Technical requirements needed to enable an improvement in focusing efficiency
were identified and understood. Moreover, alternative solutions providing
stronger focusing while using profiled crystals were proposed.Comment: Master's thesi
Synthesis and characterization of lithium-salt complexes with difluoroalkoxyborates for application as lithium electrolytes
Polymer-in-Salt Electrolytes based on Acrylonitrile/ Butyl Acrylate Copolymers and Lithium Salts
High performance of low-temperature electrolyte for lithium-ion batteries using mixed additives
Investigations on the Interaction of Dichloroaluminum Carboxylates with Lewis Bases and Water: an Efficient Road toward Oxo- and Hydroxoaluminum Carboxylate Complexes
A series of dichloroaluminum carboxylates [Cl<sub>2</sub>Al(O<sub>2</sub>CR)]<sub>2</sub> (were R = Ph (<b>1a</b>), <sup>t</sup>Bu (<b>1b</b>), CHCH<sub>2</sub> (<b>1c</b>) and
C<sub>11</sub>H<sub>23</sub> (<b>1d</b>)) were prepared and
extended
investigations on their structure and reactivity toward various Lewis
bases and H<sub>2</sub>O performed. Compounds [Cl<sub>2</sub>Al(O<sub>2</sub>CR)]<sub>2</sub> and their adducts with Lewis bases show a
large structural variety, featuring both molecular and ionic forms
with different coordination numbers of the metal center and various
coordination modes of the carboxylate ligand. Upon addition of a Lewis
base of moderate strength the molecular form [Cl<sub>2</sub>Al(O<sub>2</sub>CR)]<sub>2</sub> equilibrates with new ionic forms. In the
presences of 4-methylpyridine the six-coordinate Lewis acid–base
adducts [Cl<sub>2</sub>Al(λ<sub>2</sub>-O<sub>2</sub>CR)(<i>py</i>-Me)<sub>2</sub>] [R = Ph (<b>3a</b>), <sup>t</sup>Bu (<b>3b</b>)] with a chelating carboxylate ligand were formed.
The reactions of <b>1a</b>, <b>1b</b>, and <b>1d</b> with 0.33 equiv of H<sub>2</sub>O in THF-toluene solution lead to
oxo carboxylates [(Al<sub>3</sub>O)(O<sub>2</sub>CR)<sub>6</sub>(THF)<sub>3</sub>] [AlCl<sub>4</sub>] [where R = Ph (<b>4a</b><sub>THF</sub>), <sup>t</sup>Bu (<b>4b</b><sub>THF</sub>), and C<sub>11</sub>H<sub>23</sub> (<b>4d</b><sub>THF</sub>)] in high yield. The
similar reaction of <b>1c</b> in tetrahydrofuran (THF) afforded
the chloro(hydroxo)aluminum acrylate [(ClAl)<sub>2</sub>(OH)(O<sub>2</sub>CC<sub>2</sub>H<sub>3</sub>)<sub>2</sub> (THF)<sub>4</sub>][AlCl<sub>4</sub>] (<b>5</b>), while the hydrolysis of <b>1b</b> in MeCN lead to the hydroxoaluminum carboxylate [Al<sub>2</sub>(OH)(O<sub>2</sub>C<sup>t</sup>Bu)<sub>2</sub>(MeCN)<sub>6</sub>][AlCl<sub>4</sub>)<sub>3</sub>] (<b>6</b>). All compounds
were characterized by elemental analysis, <sup>1</sup>H, <sup>27</sup>Al NMR, and IR spectroscopy, and the molecular structure of <b>1a</b>, <b>3a</b>, <b>3b</b>, <b>4a</b><sub>THF</sub>, <b>4b</b><sub>THF</sub>, <b>4b</b><sub><i>py‑</i>Me′</sub>, <b>5</b>, and <b>6</b> were determined by single-crystal X-ray diffraction. The study provides
a platform for testing transformations of secondary building units
in Al-Metal–Organic Frameworks toward H<sub>2</sub>O and neutral
donor ligands