Reversion and Reaging in an Al-2at%Zn-2at%Mg Alloy

Kinetics of reversion and reaging of an Al-2at%Zn-2at%Mg alloy have been studied by resistivity measurements and tensile tests. Perfect reversion occurred only when aged at 20°C. The formation of the transition phase was found to occur in parallel with the dissolution of zones when the specimen aged at 70°C was reverted at 200°C. An incubation period accompanied with initial fast and slow reactions was observed in reaging. When the aging prior to reversion was ceased before the end of fast reaction, the incubation period was not observed, similarly in the case of Al-Cu alloy. It will be clear that the nucleation is necessary for zone formation in Al-Zn-Mg alloys. The initial fast and slow reactions will be explained in terms of the amount of vacancies compared with the number of solute atoms after reversion

On the Two-Stage Aging of Al-Mg-Si Alloys

The two-stage aging effect in three Al-Mg-Si alloys containing 0.5, 1.0 and 1.5% Mg₂Si respectively is investigated by electrical resistivity measurements, tensile tests and electron microscopy. The critical temperature for homogeneous nucleation of precipitates exists between 160 and 200°C for an 1.0% Mg₂Si alloy, and for an 1.5% Mg₂Si alloy between 200 and 260°C. The Temperatures are also correspoding to the highest temperatures for the resistivity increase respectively. The slight decrease in resistivity perhaps due to redissolution of clusters is observed for 0.5% Mg₂Si alloy in the initial stage of isothermal aging at a low temperature. The activation energy Eₛ for migration of solute atoms in the fast reaction is estimated as 0.77 eV for all three alloys in good agreement with the values reported for a 1.4% Mg2Si alloy. The deleterious effect of two-stage aging is observed in only limited cases, though it appearts unfortunately often in practice. The whole effect of two-stage aging appears to be explained only by the stability of clusters or zones formed during preaging. The conservation in zone number is not observed. The nucleation or stabilization of clusters which takes place during heating to aging temperature must be considered not only for quenching effect but also for two-stage aging effect

On the Precipitation in Aluminium-Zinc-Magnesium Alloys

The precipitation characteristics in Al-5wt% Zn-2wt% Mg alloys with or without a trace addition of Ag, Cu or Cr have been studied as the function of solution temperature and time, quenching temperature and medium, and pre-aging between quenching and artificial aging mainly by electrical resistivity measurement and tensile test. Imperfections such as sub-boundaries still remained after incomplete solution treatment, though it is particularly the case when added Cr, influence remarkably the following precipitation. Vacancy-solute clusters, which could be formed during or immediately after quenching, can act as precipitation nuclei of η' intermediate phase and, therefore, influence considerably the age-hardening at higher temperatures. Pre-aging and small additions of Ag have also many favorable effects on higher temperature aging

葉緑体核様体タンパク質CND41の生化学的機能解析

京都大学0048新制・課程博士博士(農学)甲第8529号農博第1138号新制||農||807(附属図書館)学位論文||H12||N3432(農学部図書室)UT51-2000-J38京都大学大学院農学研究科農芸化学専攻(主査)教授 佐藤 文彦, 教授 關谷 次郎, 教授 大山 莞爾学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDFA

A spontaneous tRNA suppressor of a mutation in the Chlamydomonas reinhardtii nuclear MCD1 gene required for stability of the chloroplast petD mRNA

Numerous nuclear gene products are required for the correct expression of organellar genes. One such gene in the green alga Chlamydomonas reinhardtii is MCD1, whose product is required for stability of the chloroplast-encoded petD mRNA. In mcd1 mutants, which are non-photosynthetic, petD mRNA is degraded by a 5′–3′ exonuclease activity, resulting in a failure to synthesize its product, subunit IV of the cytochrome b (6)/f complex. Here, we report the sequence of the wild-type MCD1 gene, which encodes a large and novel putative protein. Analysis of three mutant alleles showed that two harbored large deletions, but that one allele, mcd1-2, had a single base change resulting in a nonsense codon near the N-terminus. This same mutant allele can be suppressed by a second-site mutation in the nuclear MCD2 gene, whereas mcd2-1 cannot suppress the deletion in mcd1-1 (Esposito,D. Higgs,D.C. Drager,R.G. Stern, D.B. and Girard-Bascou,J. (2001) Curr. Genet., 39, 40–48). We report the cloning of mcd2-1, and show that the mutation lies in a tRNA(Ser)(CGA), which has been modified to translate the nonsense codon in mcd1-2. We discuss how the existence of a large tRNA(Ser) gene family may permit this suppression without pleiotropic consequences

Opiskelijoiden osallistaminen aktiivisemmiksi toimijoiksi : Pohjois- Karjalan koulutuskuntayhtymä Joensuu Tekniikan yksikkö

Kehittämishankkeeni tavoitteena on saada esille mahdollisuuksia, joiden avulla Pohjois-Karjalan koulutuskuntayhtymän Joensuu Tekniikan yksikön opiskelijat saataisiin aktiivisemmin osallistumaan opiskelijakunnan hallituksen (JOPO) järjestämiin tapahtumiin ja tempauksiin. Yhtenä osa-alueena opinnäytetyöni käsittelee osallisuuden tasoja sekä sosiaalisen vahvistamisen käytänteitä, joiden avulla osallisuus toteutuisi nykytilaa paremmin. Osallisuuteen liittyy vahvasti tieto itseä koskevista asioista, eikä myöskään kokemusta itseä koskeviin vaikutusmahdollisuuksiin voi unohtaa. Ammattialalle opinnäytetyöstä tekee ajankohtaisen se kuinka sosiaalinen vahvistaminen toteutuu ammattiopetuksen arjessa. Opinnäytetyössä käsitellään sosiaalisten vahvistamisen näkökulmaa kehitettäessä toiminnasta opiskelijalähtöistä sekä kuinka opiskelijoiden omaa kansalaisvaikuttamista voitaisiin kehittää innostavuudella. Opinnäytetyötä varten hankitun aineiston avulla JOPO saa tietoa, missä formaateissa Tekniikan yksikön opiskelijat haluavat heitä koskevista tapahtumista tiedotettavan sekä millä tasolla opiskelijoiden tietous on heille järjestetyistä tapahtumista. Opinnäyteyö tarjoaa näkökulmia ja idoita, millä keinoin opiskelijalähtöisyyttä voitaisiin kehittää, että Tekniikan yksikön opiskelijat saataisiin paremmin innostettua ja osallistettua yhteisiin tapahtumiin sekä toimimaan aktiivisempina vaikuttajina omassa oppimisympäristössään. Aineistosta sain selville kuinka tapahtumista tiedottamiseen haluttaisiin kehitystä. Vaikutusmahdollisuuksien koetaan paranevan, jos opiskelijat tietäisivät paremmin, kuinka oppilaitoksessa voi vaikuttaa sekä mitkä asiat vaikuttavat opiskelijoiden aktiivisuutta lisäävästi. Tarkastelen opiskelijalähtöisyyttä vertaistuen, sosiaalisen vahvistamisen käytänteiden, osallisuuden tasojen sekä yhteisötoiminnan kautta. Käsittelen myös opiskelijoiden itsensä vastuuta omasta aktiivisuudesta ja osallisuuteen vaikuttavista näkökulmista.The goal of my development project is to bring out ways to get students of Pohjois-Karjalan koulutuskuntayhtymä Joensuu Tekniikan yksikkö to take part in events organized by the student board (JOPO) more active. This thesis partly covers levels of participation and customs of social empowerment which will improve participation. Participation has to do with knowledge of those matters that involves students. This thesis is topical because of how social empowerment occurs in daily professional training. In thesis I process point of view of social empowerment to make activity more student oriented and how to raise students’ civil activity skills by improving motivation. The material acquired for this thesis will give knowledge to JOPO in which formats the students of technical unit want information of events and how well the students think they have been informed about those events. Thesis also offers point of views and ideas how to improve student oriented approach so that students would be more motivated, participate events more active and work mor e active to effect on their school environment. I found out from the material that students wanted that events should be announced earlier. Students feel that their ways to affect would be better if they knew how they can affect in their school. I examine student oriented approaching by peer supporting, knowledge of social empowerment, levels of participation and co-working. I also reflect students’ responsibility of their own activity and the point of views that effect on participation

Remission of anorexia nervosa after thyroidectomy: A report of two cases with Graves' disease and anorexia nervosa

We report two patients with anorexia nervosa and Graves' disease who received subtotal thyroidectomy for Graves' disease and concomitantly experienced remission from anorexia nervosa. Both were young women (aged 20 and 26) at the time of surgery. Both had well controlled thyroid function and eating behavior at the time of surgery. Both were followed for over five years without relapse of anorexia nervosa or hyperthyroidism. These cases suggest the existence of an endocrine factor originating from the thyroid gland that is involved in the pathogenesis of anorexia nervosa. Since patients of thyroidectomy can remain in good health with supplement of thyroxine alone, it can be hypothesized that this anorexigenic endocrine factor is an evolutionary relic not necessary for the normal function of humans and does not have physiological effects unless secreted beyond normal levels. Given that, it implies the existence of a creature in the animal kingdom for which such an anorexigenic hormone is essential for survival. Migrating birds eat beyond their caloric expenditure before migration and become anorexic for the duration of their flight. It is also known that their thyroid function is elevated during migration. The normal physiology of migration is a complex mechanism involving the hypothalamic, pituitary, thyroid, adrenal and reproductive hormones. The mechanism of disease, however, can be simpler. A review of the literature is presented that suggest a heretofore unreported thyroid hormone, which is involved in the regulation of migration behavior, may be the responsible factor behind anorexia nervosa

Nickel–NHC-Catalyzed Cross-Coupling of 2-Methylsulfanylbenzofurans with Alkyl Grignard Reagents

NiCl2(PPh3)(IPr) catalyzes cross-coupling reactions of 2-methylsulfanylbenzofurans with alkyl Grignard reagents. Other nickel complexes such as NiCl2(dppe) failed to catalyze the same reaction. The alkylation is applicable to the synthesis of a couple of protein tyrosine phosphatase inhibitors, 3-(4-biphenylyl)-2-alkylbenzofurans