A user's guide to the M.I.T. world energy demand data base

Prepared in association with the Sloan School of Management and the Dept. of EconomicsNational Science Foundation under Grant #GSF SIA75-0073

Cooperation of a ubiquitin domain protein and an E3 ubiquitin ligase during chaperone/proteasome coupling

Background: Molecular chaperones recognize nonnative proteins and orchestrate cellular folding processes in conjunction with regulatory cofactors. However, not every attempt to fold a protein is successful, and misfolded proteins can be directed to the cellular degradation machinery for destruction. Molecular mechanisms underlying the cooperation of molecular chaperones with the degradation machinery remain largely enigmatic so far. Results: By characterizing the chaperone cofactors BAG-1 and CHIP, we gained insight into the cooperation of the molecular chaperones Hsc70 and Hsp70 with the ubiquitin/proteasome system, a major system for protein degradation in eukaryotic cells. The cofactor CHIP acts as a ubiquitin ligase in the ubiquitination of chaperone substrates such as the raf-1 protein kinase and the glucocorticoid hormone receptor. During targeting of signaling molecules to the proteasome, CHIP may cooperate with BAG-1, a ubiquitin domain protein previously shown to act as a coupling factor between Hsc/Hsp70 and the proteasome. BAG-1 directly interacts with CHIP; it accepts substrates from Hsc/Hsp70 and presents associated proteins to the CHIP ubiquitin conjugation machinery. Consequently, BAG-1 promotes CHIP-induced degradation of the glucocorticoid hormone receptor in vivo. Conclusions: The ubiquitin domain protein BAG-1 and the CHIP ubiquitin ligase can cooperate to shift the activity of the Hsc/Hsp70 chaperone system from protein folding to degradation. The chaperone cofactors thus act as key regulators to influence protein quality control

Distribution of iron-titanium oxides in the vanadiferous main magnetite seam of the upper zone : Northern limb, Bushveld complex

The main magnetite seam of the Upper Zone of the Rustenburg Layered Suite (SACS, 1980) on the Bushveld Complex is known to host the world‘s largest vanadium bearing titaniferous iron ores. The vanadiferous titanomagnetites, contain vanadium in sufficient concentrations (1.2 - 2.2 per cent V₂O₅) to be considered as resources and vanadium has been mined historically by a number of companies among them Anglo-American, Highveld Steel and Vanadium and VanMag Resources as well as currently by Evraz Highveld Steel and Vanadium Limited of South Africa. The titanomagnetites contain iron ore in the form of magnetite and titanium with concentrations averaging 50-75 per cent FeO and 12-21 per cent TiO₂. The titaniferous iron ores have been historically dismissed as a source of iron and titanium, due to the known difficulties of using iron ore with high titania content in blast furnaces. The economic potential for the extractability of the titaniferous magnetites lies in the capacity of the ores to be separated into iron rich and titanium rich concentrates usually through, crushing, grinding and magnetic separation. The separatability of iron oxides and titanium oxides, is dependent on the nature in which the titanium oxide occurs, with granular ilmenite being the most favourable since it can be separated from magnetite via magnetic separation. Titanium that occurs as finely exsolved lamellae or as iron-titanium oxides with low titania content such as ulvospinel render the potential recoverability of titanium poor. The Upper Zone vanadiferous titanomagnetites contain titanium in various forms varying from discrete granular ilmenite to finely exsolved lamellae as well as occurring as part of the minerals ulvospinel (Fe₂TiO₄) and titanomagnetite (a solid solution series between ulvospinel and magnetite) . Discrete ilmenite constitutes between 3-5 per cent by volume of the massive titanomagnetite ores, and between 5-10 per cent by volume of the magnetite-plagioclase cumulates with more than 50 per cent opaque oxide minerals. The purpose of this research was to investigate the mineralogical setting and distribution of the iron and titanium oxides within the magnetitite layers from top to bottom as well as spatially along a strike length of 2 000m to determine the potential for the titanium to be extracted from the titanomagnetite ores. The titanomagnetites of the Upper Zone of the Bushveld Complex with particular reference to the Northern Limb where this research was conducted contains titanium oxides as discrete ilmenite grains but in low concentrations whose potential for separate economic extraction will be challenging. The highest concentration of titanium in the magnetite ores is not contained in the granular ilmenite, but rather in ulvospinel and titanomagnetite as illustrated by the marked higher concentration of TiO₂ in the massive ores which contain less granular ilmenite in comparison to the disseminated ores which contain 3 to 8 percentage points higher granular ilmenite than the massive ores. On the scale of the main magnetite seam, the TiO₂ content increases with increasing stratigraphic height from being completely absent in the footwall anorthosite. The V₂2O₅ content also increases with stratigraphic height except for in one of the 3 boreholes where it drops with increasing height. The decrease or increase patterns are repeated in every seam. The titanomagnetites of the main magnetite seam display a variety of textures from coarse granular magnetite and ilmenite, to trellis ilmenite lamellae, intergranular ilmenite and magnesian spinels and fine exsolution lamellae of ulvospinel and ferro-magnesian spinels parallel to the magnetite cleavage. The bottom contact of the main magnetite seam is very sharp and there is no titanium or vanadium in the footwall barely 10cm below the contact. Chromium is present in the bottom of the 4 layers that constitute the main magnetite seam and it upwards decreases rapidly. In boreholes P21 and P55, there are slight reversals in the TiO₂ and V₂O₅ content towards the top of the magnetite seams

Von temporär vernetzten Grenzflächenfilmen zu Mikrokapseln

Durch die vielfältigen technischen Anwendungsmöglichkeiten mikroverkapselter Systeme besteht ein stetiges Interesse an neuartigen Grenzflächen- und Membranfilmen, die eine effektive Stabilisierung von Emulsionstropfen ermöglichen. Im Rahmen dieser Dissertation wurden erstmals temporär vernetzte Mikrokapseln entwickelt, charakterisiert und ihr Verhalten in externen Zentrifugal- und Scherfeldern untersucht. Im Vordergrund stand dabei der Vergleich zweier unterschiedlicher Substanzklassen, Sorbitanester und Rinderserumalbumin (BSA). Beide Systeme bildeten durch Selbstorganisation der amphiphilen Moleküle viskoelastische Filme an Phasengrenzflächen. Eine besondere Aufmerksamkeit gilt dem Sorbitanester Span 65, dessen Filme sich bereits in vorherigen Arbeiten durch eine ausgeprägte Viskoelastizität auszeichneten. Mittels verschiedener strukturanalytischer Methoden konnte die Ursache ihrer Viskoelastizität aufgeklärt werden. Dieser makroskopische rheologische Effekt kam allein durch die Existenz der monomolekularen Schicht zustande, die aus einer Kombination aus festen Schollen und fluiden Schaumstrukturen besteht und dem System eine ausgeprägte Flexibilität verleiht. Die Proteinfilme bildeten ebenfalls temporäre Netzwerke. Diese ließen sich durch gezielte Vernetzungsreaktionen in permanente Netzwerke umwandeln, welche vergleichbare Elastizitäten aufweisen. Dies ermöglicht eine sehr gezielte Anpassung der Filmeigenschaften an die gewünschten Anforderungen (z.B. Stabilität, Flexibilität etc.). Auf Basis der erhaltenen Ergebnisse konnten Mikrokapseln entwickelt werden, deren Stabilisierung durch die Selbstorganisation der grenzflächenaktiven Substanzen zustande kam. Diese Partikel vereinen die Vorteile von Flüssigkeitstropfen und permanent vernetzten Kapseln, was sie für eine Vielzahl an Anwendungen interessant macht. Im Vergleich zu klassischen Polymerkapseln mit Polysiloxan- oder Polyacrylamidmembranen bieten temporär vernetzte Kapseln die Vorteile einer einfachen Herstellung, gut reproduzierbarer Eigenschaften, ultradünnen Wandstärken und einer augeprägten Biokompatibilität. Ihre außergewöhnliche Deformierbarkeit bei gleichzeitig hoher Stabilität ist insbesondere für die Modellbetrachtung biologischer Zellen interessant. Die Regenerationsfähigkeit der temporären Netzwerke verhindert außerdem die Zerstörung der Kapseln unter äußerer Belastung, was für eine Vielzahl von Simulationsprozessen von großer Bedeutung ist. In einer Reihe von Experimenten konnten charakteristische Deformations- und Orientierungsmodi gefunden werden, welche bisher primär für Mikrokapseln mit festkörperartiger Hülle bekannt sind. Die Ergebnisse der Kapseluntersuchungen in externen Kraftfeldern ergaben insgesamt ähnliche Werte für die Elastizität, Komprimierbarkeit und die Stabilität gegenüber Scher- und Dehnkräften und ermöglichten somit die umfassende Charakterisierung der Kapseln im Hinblick auf zukünftige Anwendungen

Cadmium Uptake in Plants as Influenced by Selenium Uptake and Sulphate Availability

With cadmium uptake by plants posing a risk to plants and consumers alike, strategies to reduce metal uptake are desirable. One strategy may be to apply selenium (as selenate) to the growth medium. I hypothesized selenate would yield greater lignification, with a higher proportion of cadmium bound to root cell walls. Consequently, higher selenium in plants would result in greater tolerance to cadmium. Additionally, since selenate is taken up in place of sulphate, providing the plants with high sulphate would inhibit uptake and translocation of selenium, mitigating selenate’s benefits of reducing cadmium uptake and translocation. Experimental results did not support these hypotheses. Selenate did not affect lignification, nor yield lower cadmium uptake and translocation. Rather, shoot selenium and cadmium concentrations were positively correlated. Thus, the safety of consuming plants from where cadmium concentrations are elevated appears unlikely to be improved by applying selenate, and potential for harm may increase

Nachgefragt: Christian Demand und Ingo Meyer zur Lage der Ästhetik

Meyer I, Demand C. Nachgefragt: Christian Demand und Ingo Meyer zur Lage der Ästhetik.; 2013