The protein-protein interactions (PPIs) occur when two or more proteins are bound together. Also, this protein-protein interactions (PPIs) cause the various biological processes in the body. Due to this reason, abilities of controlling or inhibiting PPIs can give us promising advantages like (1) better understanding of biological systems, (2) development of new diagnostic approaches for health or disease, and (3) establishment of novel molecular therapeutics. Many proteins adopt the secondary structures, where most of protein-protein interactions take place. -Helices and -sheets are the prevalent secondary conformations, but there are extended secondary structures such as -hairpins, -turns, 310 helix, and so on. As a result, construction of molecules mimicking these protein secondary structures is tractable target for drug design. Moreover, in drug discovery, designing peptidomimetics or non-peptidic mimetics is a popular strategy instead using peptides or truncated peptides because peptides or truncated peptides are prone to proteolysis and degraded in the body. Also, peptidomimetics and non-peptidic mimetics have not only the similar topology as peptides but also resistance to proteolysis. Due to these advantages, in this study, peptidomimetics or non-peptidic mimetics were synthesized and tested for different targets: (1) synthesis of non-peptidic -helical mimetics for p53-MDM2 inhibition, (2) solution-phase synthesis of -hairpin peptide for the inhibition of multiple myeloma cells (MM) adhesion, and (3) synthesis of -hairpin peptoid-peptide hybrids. The synthesis in all three different studies was succeeded, but they still need some improvements. For instance, non-peptidic -helical mimetics, terpyrimidyl derivatives, were synthesized successfully, but they did not show any bioactivity against p53-MDM2. Also, they have a solubility problem. Based on these results, it is necessary to improve the pharmacokinetic properties and bioactivity by changing the substituents on the rings or structures. The -hairpin peptide for the second case already showed good bioactivity against multiple myeloma (MM). For the next level of bio-study, the considerable amount of a -hairpin peptide was demanded. In order to make the substantial -hairpin peptide, the solution phase peptide synthesis was chosen instead of the solid phase peptide synthesis because of the cost-effect. Two methodology were tried for the solution-phase peptide synthesis: (1) segment ligation and (2) continuous synthesis. In the former case, the -hairpin peptide synthesis was successful, but, in the latter case, it is necessary to investigate the appropriate coupling reagents for each step. Peptoid-peptide hybrids has been one of the popular peptidomimetics in the last two decades. Also, mimicking the peptide secondary structure in peptoids has been studied extensively these days. The combination of these two factors was the goal for the third case. Because peptoid-peptide hybrids with a secondary structure can be recognizable by native proteins and resistant to proteolysis. So far, three sets of peptoid-peptide hybrids were synthesize and checked the secondary structure formation by using NMR. However, there was no indication of the secondary structure formation in the three sets of peptoid-peptide hybrids. This result suggests that it is necessary to introduce the more constrained components in peptoid-peptide hybrids. In the above three chapters, it has been tried to find the new drug candidates by synthesizing peptidomimetics or non-peptidic mimetics. Even though the synthesis was successful, some intended results such as the bioactivity or the secondary structure formation were not obtained. However, these results can give us the inspirations to improve properties of peptidomimetics or non-peptidic mimetics for a certain purpose, which leads to earn the intended results and eventually find new drug candidates.

Dans un contexte où l’électronique est au centre de notre société, la productiond’appareils de plus en plus compacts et multifonctionnels concentre les efforts en rechercheet développement. Pour répondre à cette attente, une des options est d’augmenter lerendement volumique des composants passifs tels que les condensateurs, en se basant surl’utilisation de nanoparticules diélectriques du type BaTiO3. Dans un premier temps,l’objectif est d’optimiser la synthèse des nanoparticules de BaTiO3 et de comprendre leursmécanismes de formation en milieux fluides supercritiques. Pour ce faire nous avonscombiné des méthodes d’analyses ex situ telles que la microscopie électronique, ladiffraction des rayons X, et les spectroscopies Raman ou infra rouge à des mesures in situsynchrotron de diffraction des rayons X aux grands angles. L’étude a par la suite ététransposé à l’élaboration de la totalité des solutions solidesBa1-xSrxTiO3 (0 ≤ x ≤ 1) et BaTi1-yZryO3 (0 ≤ y ≤ 1). Une fois les synthèses optimisées, l’utilisation du spark plasma sintering(SPS) nous a permis de mettre en oeuvre des céramiques denses et nanostructurées,préservant la taille initiale des particules (20 nm), ceci afin d’étudier les propriétésintrinsèques des matériaux à l’échelle nanoscopique. Enfin, connaissant les propriétés debase de ces nanomatériaux, nous avons pu commencer à développer des matériauxhybrides diélectriques pour l’électronique flexible. / In a context where the electronic is at the center of our society, theproduction of more compact and multifunctional devices focuses the research efforts.To answer to the expectations, one option is to improve the volume efficiency ofpassive components such as capacitors using dielectric nanoparticles such asBaTiO3. First, the objective is to optimize the synthesis of BaTiO3 nanoparticles andunderstand their formation in supercritical fluids. To do this, we combinedconventional ex situ analyses such as X-ray diffraction, electronic microscopy,infrared and Raman spectroscopies with in situ synchrotron wide angle X-rayscattering analyses. This was then transferred to the development of Ba1-xSrxTiO3 (0≤ x ≤ 1) and BaTi1-yZryO3 (0 ≤ y ≤ 1) solid solutions. Once the syntheses wereoptimized, using spark plasma sintering (SPS), we processed the powders intodense and nanostructured ceramics keeping the starting particles size (20 nm), tostudy the materials intrinsic properties at the nanoscale. Finally, knowing thenanoparticles properties, we could start to develop hybrid dielectric materials forflexible electronics.

In the first study, superconducting 2D NbSe₂ was examined towards its prototypical demonstration as a transition-edge sensor, where photoexcitation caused a thermodynamic phase transition in NbSe₂ from the superconducting state to the normal state. The efficacy of the optical absorption was found to depend on the wavelength of the incoming radiation used, which ranged from the ultra-violet (405 nm), visible (660 nm), to the infrared (1060 nm). In the second case involving WSe₂, the UV-ozone treatment revealed the presence of localized excitonic emission in 1L WSe₂ that was robust and long-lived. Our third material platform dealt with hybrid 0D-2D ensembles based on graphene and WSe₂, specifically graphene–endohedral, WSe₂–fullerene (C₆₀), and WSe₂–Au nanoparticles, and exhibited exceptional performance gains achieved with both types of hybrid structures. Next, we investigated WSe₂ based mixed dimensional hybrids. Temperature T-dependent and wavelength λ-dependent optoelectronic transport measurements showed a shift in the spectral response of 1L WSe₂ towards the SPR peak locations of Au-Sp and Au-BP, fostered through the plexciton interactions. Models for the plexcitonic interactions are proposed that provide a framework for explaining the photoexcited hot charge carrier injection from AuNPs to WSe₂ and its influence on the carrier dynamics in these hybrid systems. Last, we studied interactions of vdWs hybrid structures composed of WSe₂ with 0D buckminsterfullerene (C₆₀) spheres. Our results indicate that the C₆₀-WSe₂ vdWs hybrid heterostructure appears to be an attractive architecture for enabling charge transfer and high performance photodetection capabilities. T-dependent electrical transport measurements after C₆₀ deposition revealed a dominant p-type conduction behavior and a significant ×10³ increase in WSe₂ field-effect mobility, with a maximum field-effect mobility of 281 cm²V⁻¹s⁻¹ achieved at 350 K and room-T mobility of 119.9 cm²V⁻¹s⁻¹ for the C₆₀-WSe₂ hybrid.

Hybrid macrocycles, which chimerically integrate multiple chemical compositions and architectures, provide an effective way to impart new properties to polymers that are not found in their linear or homocyclic analogues. This dissertation addresses the incorporation of hydrophilic blocks into hydrophobic polymer, as either a poly(dimethyl siloxane)-block-poly(oxyethylene) (PDMS-POE) tadpole with a hydrophobic head and a hydrophilic tail or as a diblock poly(styrene)-block-diethylene glycol (PS-DEG) hydrophobic-hydrophilic macrocycle. The supramolecular association properties of both kinds of cycles were studied: the PDMS-POE tadpoles in forming micelles, and the PS-DEG macrocycles in threading with linear polymer to form polyrotaxanes. For the PDMS-POE macrocycle, linear alpha,omega-dihydroxy PDMS was cyclized under dilute conditions with dichloromethylhydrosilane as a linking group to produce hydrosilane-functionalized cyclic PDMS. This was joined to alpha-methoxy,omega-allyl POE via a free radical hydrosilylation reaction to produce the hybrid tadpole macrocycle, which was analyzed by GPC, DSC, and 1H, 13C, and 29Si NMR spectroscopy. Supramolecular aggregation consisting of the formation of micelles under both polar and nonpolar conditions was studied by surface tensiometry and quasielastic light scattering. For the PS-DEG macrocycle, linear alpha,omega-dihydroxy PS was prepared by ATRP polymerization of styrene, followed by reaction with KOH to give hydroxyl endgroups. The linear PS was then cyclized under dilute conditions with diethylene glycol ditosylate, and the product was analyzed by GPC, MALDI-TOF MS, DSC, and 1H, 13C and DOSY NMR spectroscopy. The macrocycle was then statistically threaded with linear PS to give the supramolecular structure poly(styrene)-rotaxa-cyclo[poly(styrene)-block-diethylene glycol]. Characterization was performed with DOSY NMR to verify that the product was threaded, and 1H NMR was collected to determine that the product was 13% macrocycle by weight. DSC showed only one Tg, indicating that the linear and cyclic species were present in the same phase.

The development of a new family of robotic vehicles for use in the exploration of Mars and other remote planets is an ongoing process. Current rovers have to traverse rough terrain and be able to withstand various conditions on Mars. The goal of this project is to design a new Mars rover mobility system that performs to optimum capability. This project will involve the design and control of a robot that will use wheels, as well as legs, allowing the robot to reconfigure itself to adapt to its current environment and traverse various terrains. This new reconfigurable hybrid robotic vehicle, Byrobot (named after the student), will have a six-legged mobility design for walking. Each leg will have 3 degrees of freedom, controlled by 3 separate servos, for the movement of the legs. Byrobot will also have 4 wheels each directly attached to the shaft of a DC motor, for four-wheel differential drive. By having these two mobility systems, Byrobot will be able to operate in various environments, by capitalizing on the advantages of both legged and wheeled robots. The CAD designing for this new robot is done on Pro-Engineer, and mechanisms and animations will be run to test movement of parts. The actual robot hardware will then be constructed in the Georgia Tech MRDC machine shop. The control system for the robot will be run by the Eyebot, which uses a 25MHz 32bit Controller (Motorola 68332), as well as the SSC-32 Servo Controller from Lynxmotion. This new robotic mobility platform will facilitate future Mars exploration.

Mixed matrix membranes offer an attractive route to the development of high performance and efficiency membranes required for demanding gas separations. Such membranes combine the advantageous processing characteristics of polymers with the excellent separation productivity and efficiency of molecular sieving materials. This research explores the development of mixed matrix membranes, namely in the form of asymmetric hollow fiber membranes using zeolites as the molecular sieving phase and commercially available high performance polymers as the continuous matrix. Lack of adhesion between the typically hydrophobic polymer and the hydrophilic native zeolite surface is a major hurdle impeding the development of mixed matrix membranes. Silane coupling agents have been used successfully to graft polymer chains to the surface of the zeolite to increase compatibility with the bulk polymer in dense films. However, transitioning from a dense film to an asymmetric structure typically involves significant processing changes, the most important among them being the use of phase separation to form the asymmetric porous structure. During the phase separation, it is believed that hydrophilic sieves can act as nucleating agents for the hydrophilic polymer lean phase. Such nucleation tendencies are believed to lead to the formation of gaps between the polymer and sieve resulting in poor mixed matrix performance. This research focuses on defining procedures and parameters to form successful mixed matrix hollow fiber membranes. The first part of this dissertation describes dope mixing procedures and unsuccessful results obtained using a silane coupling agent to enhance polymer-zeolite adhesion. The next section follows the development of a highly successful surface modification technique, discovered by the author, employing the use of a Grignard reagent. As a test case, two zeolites of different silicon-to-aluminum ratios are successfully modified and used to develop mixed matrix membranes with greatly increased gas separation efficiencies. The broad applicability of the surface treatment is also demonstrated by the successful incorporation of the modified zeolites in a second polymer matrix. The final section of the work describes the novel occurrence of large defects (macrovoids) caused by the presence of large zeolite particles proposing a particle size effect in the formation of such defects.

Phosphofructokinase from Escherichia coli (EcPFK) is allosterically regulated by MgADP and phospho(enol)pyruvate (PEP). Both molecules compete for binding to the same allosteric site, however, MgADP activates and PEP inhibits the binding of fructose-6-phosphate (F6P) to the active site. The mode by which this enzyme can differentiate between the two ligands and cause the appropriate response is important for the understanding of the basis of allosteric regulation. We studied the interactions between an active site and an allosteric site (heterotropic interactions) within the protein, and found that each of the four unique heterotropic interactions is unique and the magnitudes of the coupling free energies for MgADP activation sum up to 100% that of wildtype EcPFK without homotropic cooperativity in F6P binding. We took on the kinetic and structural characterization of phosphofructokinase from Lactobacillus bulgaricus (LbPFK) to reveal an enzyme that exhibits allosteric properties in spite of previous kinetic studies performed by Le Bras et al. (1991). We have identified residues in EcPFK (Asp59, Gly184 and Asp273), which are important for the allosteric responses to both MgADP and PEP. Interestingly, Lys214 is only important in PEP inhibition and not MgADP activation. We can also differentially disrupt the MgADP heterotropic interactions with the introduction of G184C within the protein. These results suggest that there are different pathways for allosteric communication within the enzyme: different paths for MgADP activation and PEP inhibition, and different paths for each heterotropic interaction with Gly184 being important for the 33Å MgADP heterotropic interaction.

Hybrid plants and animals, like corn and the domestic dog, grow larger and more vigorously than their parents, a common phenomenon known as hybrid vigor or heterosis. In hybrids between Arabidopsis ecotypes or species (in allotetraploids), altered expression of circadian clock genes leads to increased starch and chlorophyll content and greater biomass. In plants and animals, circadian clock regulation plays a key role in optimizing metabolic pathways, increasing fitness, and controlling responses to biotic and abiotic stresses. In the allotetraploids, the increased level of heterosis is likely caused by interspecific hybridization as well as genome doubling. However, it is unknown how genome dosage and allelic effects influence heterosis, and whether additional clock output traits, such as stress responses, are altered in hybrids. In three related projects, the effects of genomic hybridization (including parent-of-origin effects) and genome dosage on heterosis were elucidated. In my first project, I found that although ploidy influenced many traits, including seed and cell size, biomass and circadian clock gene expression were most strongly influenced by hybridization. Additionally, parent-of-origin effects between reciprocal hybrids were frequently observed for many traits. In my second project, I described a unique role for RNA-directed DNA methylation (mainly CHH methylation) in mediating the parent-of-origin effect on expression of the circadian clock gene CCA1 in reciprocal hybrids. Altered CCA1 expression peaks were associated with heterosis of biomass accumulation in the reciprocal hybrids. Lastly, I used transcriptome sequencing in hybrids at different times of day to examine changes in downstream clock-regulated pathways. In the hybrids, many genes in photosynthetic pathways were upregulated, while many genes involved in biotic and abiotic stresses were repressed during the morning and afternoon, respectively. Additionally, natural variation between parents in stress-responsive gene expression was found to be crucial for producing vigorous hybrids. These conceptual advances increase the mechanistic understanding of heterosis, and may guide selection of parents for making better hybrids. / text

The aim of work – to determine efficienty of the Lithuanian Black-and-White cattle crossing with Charolais bull. The task of research: 1.To analyse the literature about the crossing Lithuanian Black-and-White caws with Charolais bull. 2.To determine the influence of Charolais bull on beef meat production and quality of Lithuanian Black-and-White cattle. Conclusions: 1.Charolais bulls were found to improve the weight of Lithuanian Black-and-White cattle at 18 month of age by 38.5 kg or 7.6 % (P>0,05) and reduced feed conversion per weight gain unit by 8.2 %. 2.The daily gain of the Charolais hybrids bulls was by 8.0 % bigger than that of the pure-blooded Lithuanian Black-and-White bulls. 3.Control slaughters indicated the bigger carcass mass for Charolais hybrids which was 20.7 kg, or 7.8 % bigger than the carcass mass of the pure-blooded Lithuanian Black-and-White young bulls. 4.Hybrids had a 1.5 % better carcass output, 4.0 % better ham output, and 2.4 % better output of ham edible parts in carcass, by 0.65 bigger the coefficient of succulence of this part of carcass and by 42.94 cm² bigger area of loin lean. 5.Crossbreeding had no significant influence on meat quality. A tendency was observed to lower meat pH, higher shear force and a better amino acids triptophan and oxyproline ratio 5.47 of hybrids (P<0,005). 6.It has been concluded that it is useful to use Charolais bulls for crossing with Lithuanian Black-and-White cattle of milk type.

2004 – 2005 m. Alytaus AB „Vilda“ gamybinėse gluosnių ir karklų plantacijose įrengtose lauko kolekcijose buvo atlikta gluosnio žilvičio (S. viminalis L.) ir kai kurių jo kultivarų bei hibridų klonų (S. viminalis kl. 04116, S. viminalis `Americana` žaliažievė forma kl. 9972, S. viminalis `Americana` kl. 9976, S. viminalis `Tordis`, S. purpurea x S. viminalis kl. 9714 ir kl. 04141) morfobiologiniai ir produktyvumo tyrimai. Nustatyta, kad I – II auginimo metais tirtųjų taksonų krūmai skiriasi pagal jų aukštį, atžalinių ūglių ir stiebų skaičių krūme, atžalinių ūglių vidutinį ilgį bei jų skersmenį ir nulaibėjimo pobūdį, lapų formą ir dydį, medienos ir šerdies plotį ūglio skerspjūvyje. Daugiausiai atžalinių ūglių (vytelių) antraisiais auginimo metais išaugino S. viminalis `Americana` žaliažievė forma kl. 9972 (649,8 tūkst.vnt./ha) ir S. purpurea x S. viminalis kl. 9714 (609,9 tūkst.vnt./ha). Intensyviausiu atžalinių ūglių krūmų augimu I-II-aisiais auginimo metais išsiskyrė S. viminalis `Tordis`, S. viminalis `Americana` kl. 9976 ir S. viminalis `Americana` žaliažievė forma kl. 9972. Didžiausią krūmo atžalinių ūglių masę I-II-aisiais auginimo metais išaugino S. viminalis `Americana` žaliažievė forma kl. 9972 (2004 m. – 17,1 t/ha,2005 m. – 44,4 t/ha), S. viminalis `Americana` kl. 9976 (2004 m. – 14,6 t/ha, 2005 m. – 48,9 t/ha), S. viminalis `Tordis` (2004 m. – 13,5 t/ha, 2005 m. – 34,8 t/ha). Didžiausią vieno krūmo vidutinė dvimečių... [toliau žr. visą tekstą] / In 2004 – 2006, in plantation of Alytus join stock company “Vilda”, there were researched and valued morphological characteristics and productivity of basket willow (Salix viminalis L.), some of its cultivares and clones of hybrids (S. viminalis cl. 04116, S. viminalis `Americana` green bark form cl. 9972, S. viminalis `Americana` cl. 9976, S. viminalis `Tordis`, S. purpurea x S. viminalis cl. 9714 and cl. 04141). It has been proved some differences between S. viminalis L., its cultivares and clones of hybrids in number and mass of sprouts and stems on a bush, the height of bushes, their diametre lenght and yield of twigs. The most valuable taxa of clones regarding productivity are S. viminalis `Americana` cl. 9972 (649,8 thou.unit/ha) and S. purpurea x S. viminalis cl. 9714 (609,9 thou.unit/ha). S. viminalis `Tordis`, S. viminalis `Americana` cl. 9972, S. viminalis `Americana` cl.9976 are the most intensively growing bushes and have the longest sprouts. In the field collections the highest mass of regrowth sprouts and stems are found by the clone 9976 of S. viminalis `Americana`(1828,9 gram) and S. viminalis `Tordis` (1774,9 gram). It has been discovered that within the period of 3 years taxa of S. viminalis L. reach the stated mass of dry stems per one ha: S. viminalis cl. 04116 – 35,5 t/ha, S. viminalis `Americana` žaliažievė forma cl. 9972 – 44,2 t/ha, S. viminalis `Americana` cl. 9976 – 50,1 t/ha, S. viminalis `Tordis` – 49,6 t/ha.