GBRDs over groups of orders ≤100 or of order pq with p, q primes

AbstractThere are well-known necessary conditions for the existence of a generalized Bhaskar Rao design over a group G, with block size k=3. It has been conjectured that these necessary conditions are indeed sufficient. We prove that they are sufficient for groups G of order pq where p,q are primes and for groups of all orders ≤100 except possibly 32, 36, 48, 54, 60, 64, 72, 96

Characterizing the Excited State Dynamics of Organic Materials for Efficient Energy Conversion: from Current to Photons and Vice-Versa

The use of organic semiconductor (OSC) materials for optoelectronic applications such as display technologies, consumer electronics, energy-storage, and photovoltaic conversion has drawn academic and industrial interest in recent years. The OSC rise in popularity and demand is due to their multiple advantageous properties over their inorganic counterparts. Some of these OSC properties are their ease of device processability, flexibility, and cost-efficiency. In addition, their synthetic flexibility allows for subtle modifications in their structure so their optical and electrochemical properties could be systematically tuned. The molecular structure dictates their function, therefore, fundamental understanding on how modulating their chemical structures will tune their opto-electrical properties is imperative to optimize their optoelectronic performance. In this dissertation, ultrafast spectroscopy and nonlinear optical methods were used to probe the excited state dynamics of OSC materials with 1) thermally activated delayed fluorescence (TADF) characteristics, and 2) light harvesting and low-bandgap materials for bulk heterojunction (BHJ) architectures. The former is a mechanism used for enhancing the efficiency of the third-generation organic light emitting diodes (OLEDs), while the latter composed the active layer of the third generation organic photovoltaic (OPV) devices. TADF is the idea that dark triplet excitons can be converted into emissive singlet exciton via a reverse intersystem crossing (rISC) mechanism, which the rISC is prompted by the combination of room thermal energy with the small energy gap between the singlet-triplet manifolds (ΔEST). This mechanism has been implemented into OLEDs. However, one of the major challenges hampering their commercialization is the lack of seep understanding on the overall TADF mechanism in such systems. Throughout the course of this thesis, the photophysical properties of multiple TADF emitters are elucidated. In addition, a new optical approach for the direct characterization of the rate of rISC (krISC) is introduced. This new methodology could be used to predict their respective device performances. The krISC in TADF emitters is believed to be critical for reducing the triplet-triplet annihilation (TTA) mechanism that cause efficiency roll-off at high operational voltage. In the case of the active materials for BHJ applications, the optical properties of light harvesting polymers and low-bandgap small molecules for non-fullerene acceptors (NFA) devices are elucidated. Specifically, the influence of heterocycles such as furan and thiophene as linkers on the photophysical properties of light harvesting polymers were probed with and emphasis in their charge transfer properties. These light harvesting polymers were based on benzodifuran (BDF) as the donor and diketopyrrolopyrrole (DPP) as the acceptor. The low-bandgap materials were designed to be acceptor-donor-acceptor ladder-type molecules based on perylene-diimide (PDI) as the acceptor and heteroacenes as the donor. These materials have also drawn interest for developing transparent solar cells. Their photophysical properties were investigated and an intense intramolecular charge-transfer character upon pi-conjugation lengthening was observed among them. In addition, fundamental investigation of the feasibility of intramolecular singlet exciton fission (iSF) and subsequent two-electron transfer from tetracyanimethylene quinoidal bithiophene (QOT2) to anthracene were investigated as well.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/153365/1/ricbacu_1.pd

Algebraic constructions of group divisible designs

Some series of Group divisible designs using generalized Bhaskar Rao designs over Dihedral, Symmetric and Alternating groups are obtained

Organophosphorus Chemistry 2018

Organophosphorus chemistry is an important discipline within organic chemistry. Phosphorus compounds, such as phosphines, trialkyl phosphites, phosphine oxides (chalcogenides), phosphonates, phosphinates and >P(O)H species, etc., may be important starting materials or intermediates in syntheses. Let us mention the Wittig reaction and the related transformations, the Arbuzov- and the Pudovik reactions, the Kabachnik–Fields condensation, the Hirao reaction, the Mitsunobu reaction, etc. Other reactions, e.g., homogeneous catalytic transformations or C-C coupling reactions involve P-ligands in transition metal (Pt, Pd, etc.) complex catalysts. The synthesis of chiral organophosphorus compounds means a continuous challenge. Methods have been elaborated for the resolution of tertiary phosphine oxides and for stereoselective organophosphorus transformations. P-heterocyclic compounds, including aromatic and bridged derivatives, P-functionalized macrocycles, dendrimers and low coordinated P-fragments, are also of interest. An important segment of organophosphorus chemistry is the pool of biologically-active compounds that are searched and used as drugs, or as plant-protecting agents. The natural analogue of P-compounds may also be mentioned. Many new phosphine oxides, phosphinates, phosphonates and phosphoric esters have been described, which may find application on a broad scale. Phase transfer catalysis, ionic liquids and detergents also have connections to phosphorus chemistry. Green chemical aspects of organophosphorus chemistry (e.g., microwave-assisted syntheses, solvent-free accomplishments, optimizations, and atom-efficient syntheses) represent a dynamically developing field. Last, but not least, theoretical approaches and computational chemistry are also a strong sub-discipline within organophosphorus chemistry

Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 235)

This publication is a cummulative index to the abstracts contained in Supplements 223 through 234 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included -- subject, personal author, corporate source, foreign technology, contract number, report number and accession number

Earth Resources: A continuing bibliography with indexes, issue 33

This bibliography list 436 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution sytems, instrumentation and sensors, and economic analysis

Aeronautical Engineering: A continuing bibliography with indexes, supplement 153, October 1982

This bibliography lists 535 reports, articles and other documents introduced into the NASA Scientific and Technical Information System in September 1982