Analysis of Degradation in Graphene-based Spin Valves

The degradation mechanisms of multilayer graphene spin valves are investigated. The spin injection signals in graphene spin valves have been reported to be linearly dependent on the drain bias voltage, which indicates that the spin polarization of injected spins in graphene is robust against the bias voltage. We present that the disappearance of this robustness is due to two different degradation mechanisms of the spin valves. Our findings indicate that the disappearance of the robustness is due to degradation rather than an intrinsic characteristic of graphene. Thus, the robustness can be greatly enhanced if degradation can be prevented.Comment: 14 pages, 4 figures (To appear in Applied Physics Express

Overproduction of Geranylgeraniol by Metabolically Engineered Saccharomyces cerevisiae▿

(E, E, E)-Geranylgeraniol (GGOH) is a valuable starting material for perfumes and pharmaceutical products. In the yeast Saccharomyces cerevisiae, GGOH is synthesized from the end products of the mevalonate pathway through the sequential reactions of farnesyl diphosphate synthetase (encoded by the ERG20 gene), geranylgeranyl diphosphate synthase (the BTS1 gene), and some endogenous phosphatases. We demonstrated that overexpression of the diacylglycerol diphosphate phosphatase (DPP1) gene could promote GGOH production. We also found that overexpression of a BTS1-DPP1 fusion gene was more efficient for producing GGOH than coexpression of these genes separately. Overexpression of the hydroxymethylglutaryl-coenzyme A reductase (HMG1) gene, which encodes the major rate-limiting enzyme of the mevalonate pathway, resulted in overproduction of squalene (191.9 mg liter−1) rather than GGOH (0.2 mg liter−1) in test tube cultures. Coexpression of the BTS1-DPP1 fusion gene along with the HMG1 gene partially redirected the metabolic flux from squalene to GGOH. Additional expression of a BTS1-ERG20 fusion gene resulted in an almost complete shift of the flux to GGOH production (228.8 mg liter−1 GGOH and 6.5 mg liter−1 squalene). Finally, we constructed a diploid prototrophic strain coexpressing the HMG1, BTS1-DPP1, and BTS1-ERG20 genes from multicopy integration vectors. This strain attained 3.31 g liter−1 GGOH production in a 10-liter jar fermentor with gradual feeding of a mixed glucose and ethanol solution. The use of bifunctional fusion genes such as the BTS1-DPP1 and ERG20-BTS1 genes that code sequential enzymes in the metabolic pathway was an effective method for metabolic engineering

The importance of factors related to the implementation of the physical asset management practices

Namen diplomskega dela je preučitev pomembnosti dejavnikov, ki so povezani z implementacijo dejavnosti obvladovanja fizičnih sredstev. Pričujoče diplomsko delo v teoretičnem delu obravnava pomen ISO-standardov in družino standardov SIST ISO 55000: 2017, elemente obvladovanja premoženja ter sklop šestih področij dejavnosti obvladovanja fizičnega premoženja (ang. Physical asset management). V pregledu literature so predstavljene glavne dejavnosti obvladovanja fizičnega premoženja, in sicer strategija in planiranje obvladovanja fizičnega premoženja, odločitve obvladovanja fizičnega premoženja, obvladovanje življenjskega cikla fizičnega premoženja, obvladovanje informacij fizičnega premoženja, organizacija in ljudje ter področje obvladovanja tveganj in pregledi. Za namene pridobivanja podatkov je bil uporabljen anketni vprašalnik. Raziskava je bila izvedena med slovenskimi organizacijami. Za obdelavo in predstavitev pridobljenih podatkov smo uporabili opisno statistiko. Ugotovitve raziskave kažejo, da so med anketirane organizacije kot motive za implementacijo dejavnosti obvladovanja fizičnega premoženja opredelili zadovoljevanje zahtev kupcev, biti v skladu z industrijsko politiko ter da imajo v organizaciji boljši nadzor nad procesi. Ovire za implementacijo dejavnosti fizičnega premoženja pa v anketiranih organizacijah najpogosteje predstavljajo porast dokumentacije in birokracije, dolgotrajna uvedba in pomanjkanje finančnih ter človeških virov.The purpose of this diploma thesis is to study the importance of factors that are linked with implemantation of the physical asset management practices. The existent diploma thesis in its theoretical part discusses the meaning of ISO-standards and the family of standards SIST ISO 55000: 2017, elements of management assets and a complex of six fields of physical asset management. In the literature overview it deals with the main activities of physical asset management, namely the strategy and planning, asset management decision - making, life cycle delivery, asset information, organization and people and a field of risk and review. A survey questionnaire was used in order to get the data. The research was made in Slovenian organizations. Descriptive statistics were used for processing and presenting the new data. The results of the research shows that the motives of interviewed organizations for implementing activities of physical asset management are meeting the requirements of the customers, to be in line with the industrial policy and to have better control of the processes. The obstacles to the implementation of the activities of physical assets in an organization surveyed most often represents an increase in paperwork and bureaucracy, long – lasting introduction and lack of financial and human resources