Vacuolar-type ATPases (V-ATPases) are ubiquitous membrane-bound protein complexes present in the endo-membrane system of all eukaryotic cells. In eukaryotic cells, the reversible dissociation of the V1 and Vo regions is an essential mechanism for regulating V-ATPase activity. Therefore, knowledge of the structure of the dissociated V1-ATPase is necessary for understanding the regulation of V-ATPase activity. In this thesis, I showed that by introducing a 3xFLAG tag at the C terminus of different V1-ATPase subunits, highly purified V1-ATPase complex could be isolated. Electron cryomicroscopy (cryo-EM) was used for initial analysis of the intact V1-ATPase. In addition to the intact complex, partial V1-ATPase subcomplexes with different subunit compositions were isolated from yeast cells in late log phase. All of the isolated subcomplexes were found to contain the major V1-ATPase subunits A and B, but differed in the peripheral stalk subunit composition.

No description available.

In this study, we discussed the capacitance-voltage characteristics of the GaN MOS structure with surface treatment using low energy ion beam prior to the oxide deposition. We used the E-Beam evaporator which was equipped with the ion beam assisted deposition system that originally used for optical thin film deposition. Before depositing SiO2 the surface was treated by low energy Ar+ with different processing time inside the vacuum chamber around 10-6 torr. The purpose was to reduce the density of interface states and to explore the influence of C-V characteristics of the GaN MOS structure. We have measured the high frequency C-V curve, hysteresis, and also varied the delay time while measuring. Based on the measuring results, some useful parameters of the device were obtained. Found that the deep depletion phenomenon and hysteresis were easy seen in high frequency C-V measurement. To lower the interfacial states of the sample and shorten the processing time of the low energy ion beam treatment yielded the better result.But the surface was easily damaged when the processing time was prolonged.At last we added the capacitance-voltage study of the Si MOS structure with surface treatment using low energy ion beam, and the capacitance-voltage study of the InN MOS structure.

InN films were grown on Si(111) wafer with AlN buffer layer by plasma-assisted molecular beam epitaxy (PAMBE). The sample went through a conventional cleaning process which involved sequential rinsing in acetone (5 mins), isopropyl alcohol (5 mins), de-ionized water (5 mins), and blown dry with nitrogen before SiO2 deposited. We used E-beam to deposit SiO2 thin film on InN. Ohmic contact (Ti) was prepared by e-beam evaporation. The system used to measure the high-frequency and low-frequency consists of Keithley 590 analyzer and Quasistatic CV meter. At last we added the capacitance-voltage study of the Si MOS structure and the research of growing high quality AlN for high quality InN.

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Velocity-difference induced focusing (V-DIF) with a dynamic pH junction in capillary electrophoresis (CE) using a sample with a pH different from that of the background electrolyte (BGE) was developed in our group, but the mechanism was not well understood. In this work, the mechanism of this focusing technique was first studied using an appropriate dye to monitor the pH of the BGE and the sample during the focusing process. A mechanism was proposed based on the experimental results. This technique was then applied to serotonin to improve the detection limit when CE was used with a UV absorption detector. It was also applied to focus amino acids, peptides, and proteins to improve the concentration sensitivity. It is found that the pKa rather than the pI of the analytes is the key criterion for selecting the pH for the sample and for the BGE to obtain the optimum focusing for these molecules. Since UV detection only provides migration time information, more structure information is obtained by using a photodiode array (PDA) and mass spectrometer (MS) for peak identification. Comparisons were made between the PDA detection and MS detection for aromatic amino acids with V-DIF using a dynamic pH junction. This V-DIF technique was then applied to non-aromatic amino acids with MS detection. It was used at low pH with positive ESI-MS detection and at high pH with negative ESI-MS ionization. The results of the two methods were compared and discussed. Finally, the preparative operation of continuous flow counterbalanced CE (FCCE) was studied. The effects of larger sample volumes and multiple capillary systems on improving the purification yield were investigated.

Det finns ett växande intresse för lokalodlad frukt i Sverige och det blir vanligare att plantera fruktträd i sina trädgårdar. Samtidigt sker den mesta fruktodlingen i södra Sverige. I norr är odlingssäsongen kortare vilket gör att frukten kan ha svårt att hinna mogna och det finns risk för frostskador på träd och knoppar. Tillsammans med ett bristfälligt utbud av härdiga sorter har det gjort att odling av fruktträd ur Prunussläktet som körsbär och plommon är ovanlig i Norrland. Mycket kan dock göras för att träden ska trivas genom att förbättra klimatet närmast trädet; det som kallas mikroklimat. För detta behövs kunskap om övergripande klimatfaktorer och om de ståndortskrav som Prunus har. Syftet med denna uppsats är att undersöka de faktorerna tillsammans med vilka mikroklimatförbättringar som lämpar sig för Prunus. Fokus ligger på Umeå i Västerbotten, växtzon V. Metoden som använts är litteraturstudie i kombination med intervjuer.  Resultatet visar att klimatet i Umeå enligt prognoser förväntas bli varmare med ökad nederbörd och längre växtsäsong. Förändringar av klimatet kan ha en stor inverkan på behoven av att modifiera mikroklimatet. De ståndortsfaktorer som är de mest betydande för fruktbärande Prunus är god tillgång till värme och solstrålning samt en jord som både är fuktighetshållande och väldränerad. Under våren kan knoppar och ved lätt skadas av nattfrost liksom under höst och vinter om träden inte hunnit invintra ordentligt. Mikroklimatförbättringar som kan göras är att se till att jorden är varm genom att använda en sandjord som värms upp snabbt på våren. De ger även träden bättre förutsättningar att avmogna på hösten genom att de generellt är bättre dränerade än lerjordar. För att öka mullhalt och fuktighetshållande förmåga kan organiskt material tillföras. Att höja upp odlingsbädden gör att jorden blir varmare och dräneringen fungerar bättre. Eftersom större stenar fungerar som värmemagasin kan närhet till dessa ge en varmare och jämnare temperatur för trädens rötter. Det är även gynnsamt för Prunus om odlingen placeras i en södervänd sluttning för maximal solinstrålning. En viktig faktor för att öka temperaturen är att skydda träden från vindutsatthet genom växtlighet eller byggda skydd. Spaljéring av Prunus kan skydda mot frostskador samtidigt som det kan bidra till för tidig knoppsprickning och därmed extra känslighet mot frost. Det finns ett flertal sorter av fruktträd ur Prunussläktet som är lämpade att odla i Umeå med omnejd. I slutet av arbetet finns dessa sorter listade.

Velocity-difference induced focusing (V-DIF) with a dynamic pH junction in capillary electrophoresis (CE) using a sample with a pH different from that of the background electrolyte (BGE) was developed in our group, but the mechanism was not well understood. In this work, the mechanism of this focusing technique was first studied using an appropriate dye to monitor the pH of the BGE and the sample during the focusing process. A mechanism was proposed based on the experimental results. This technique was then applied to serotonin to improve the detection limit when CE was used with a UV absorption detector. It was also applied to focus amino acids, peptides, and proteins to improve the concentration sensitivity. It is found that the pKa rather than the pI of the analytes is the key criterion for selecting the pH for the sample and for the BGE to obtain the optimum focusing for these molecules. Since UV detection only provides migration time information, more structure information is obtained by using a photodiode array (PDA) and mass spectrometer (MS) for peak identification. Comparisons were made between the PDA detection and MS detection for aromatic amino acids with V-DIF using a dynamic pH junction. This V-DIF technique was then applied to non-aromatic amino acids with MS detection. It was used at low pH with positive ESI-MS detection and at high pH with negative ESI-MS ionization. The results of the two methods were compared and discussed. Finally, the preparative operation of continuous flow counterbalanced CE (FCCE) was studied. The effects of larger sample volumes and multiple capillary systems on improving the purification yield were investigated.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Inaug.-diss.--München. / Lebenslauf. "Notenbeispiele": p. [123]-140. "Bibliographie": p. [9]-11.