Genetic and process engineering approaches for improving lipid productivity in the non-conventional oleaginous yeast Cutaneotrichosporon oleaginosus

Gli oli microbici stanno ricevendo sempre più attenzioni come possibile alternativa agli oli vegetali, nel processo di sostituzione dei combustibili fossili. Tuttavia, diversi aspetti necessitano di essere ottimizzati al fine di ottenere oli economicamente competitivi e con caratteristiche chimico-fisiche desiderate. In questa ricerca, sono stati utilizzati due differenti approcci per poter realizzare l’obiettivo preposto. Il primo, si è basato sull’ingegnerizzazione genetica del lievito C. oleaginous, al fine di incrementare la produttività di lipidi e modificare la composizione dei trigliceridi (TAG) sintetizzati. Un protocollo basato su una trasformazione genetica mediata da Agrobacterium è stato utilizzato per sovraesprimere la diacilglicerol trasnferasi (DGA1), l’enzima responsabile dell’ultimo step della sintesi dei TAG, e la Δ9-desaturasi, l’enzima che catalizza la conversione dell’acido stearico (C18:0) in acido oleico (C18:1). La selezione di colonie positive e l’analisi dei mutanti ottenuti ha confermato la buona riuscita della trasformazione. Il secondo approccio ha mirato a studiare l’influenza sulla crescita e sul profilo di lipidi accumulati da C. oleaginous da parte di diversi acidi grassi volatili (VFAs), una materia prima ottenibile da trattamenti di scarti industriali. A questo proposito, sono state utilizzate fermentazioni fed-batch su scala da 1-L basate su glucosio e miscele sintetiche di acido acetico e di VFAs come fonte di carbonio. L’utilizzo simultaneo di acido acetico e acidi secondari ha mostrato come sia possibile stimolare il metabolismo microbico al fine di incrementare l'accumulo di oli e ottenere una composizione chimica lipidica desiderata.

Electrical spectroscopy of rubrene bulk and thin film crystals

One of the most diffused electronic device is the field effect transistor (FET), contained in number of billions in each electronic device. Organic optoelectronics is an emerging field that exploits the unique properties of conjugated organic materials to develop new applications that require a combination of performance, low cost and processability. Organic single crystals are the material with best performances and purity among the variety of different form of organic semiconductors. This thesis is focused on electrical and optical characterization of Rubrene single crystal bulk and thin films. Rubrene bulk is well known but for the first time we studied thin films. The first Current-voltage characterization has been performed for the first time on three Rubrene thin films with three different thickness to extract the charge carriers mobility and to assess its crystalline structure. As results we see that mobility increase with thickness. Field effect transistor based on Rubrene thin films on $SiO_2$ have been characterize by current-voltage (I-V) analyses (at several temperatures) and reveals a hopping conduction. Hopping behavior probably is due to the lattice mismatch with the substrate or intrinsic defectivity of the thin films. To understand effects of contact resistance we tested thin films with the Transmission Line Method (TLM) method. The TLM method revealeds that contact resistance is negligible but evidenced a Schottky behavior in a limited but well determined range of T. To avoid this effect we carried out annealing treatment after the electrode evaporation iswe performed a compete I-V characterization as a function of in temperature to extract the electronic density of states (DOS) distribution through the Space Charge Limited Current (SCLC) method. The results show a DOS with an exponential trenddistribution, as expected. The measured mobility of thin films is about 0.1cm^2/Vs and it increases with the film thickness. Further studies are necessary to investigate the reason and improve performances. From photocurrent spectrum we calculated an Eg of about 2.2eV and both thin films and bulk have a good crystal order. Further measurement are necessary to solve some open problems

A ROS-based Workspace Control and Trajectory Planner for a seven degrees of freedom Robotic arm

In this Bachelor Thesis I want to provide readers with tools and scripts for the control of a 7DOF manipulator, backed up by some theory of Robotics and Computer Science, in order to better contextualize the work done. In practice, we will see most common software, and developing environments, used to cope with our task: these include ROS, along with visual simulation by VREP and RVIZ, and an almost "stand-alone" ROS extension called MoveIt!, a very complete programming interface for trajectory planning and obstacle avoidance. As we will better appreciate and understand in the introduction chapter, the capability of detecting collision objects through a camera sensor, and re-plan to the desired end-effector pose, are not enough. In fact, this work is implemented in a more complex system, where recognition of particular objects is needed. Through a package of ROS and customized scripts, a detailed procedure will be provided on how to distinguish a particular object, retrieve its reference frame with respect to a known one, and then allow navigation to that target. Together with technical details, the aim is also to report working scripts and a specific appendix (A) you can refer to, if desiring to put things together.