Diss.--Philosophische Fakultät--Bonn--Rheinische Friedrich-Wilhelms-Universität, 2002. Titre de soutenance : Jean Matal, Ioannes Matalius Metellus Sequanus (*um 1517, gest. 1597) : humanistischer Jurist und konfessioneller Ireniker, Verlagsberater und Atlaskartograf, Mitbegründer der wissenschaftlichen Epigrafik. / Bibliogr. p. 450-541. Index.

Abstract Electric contacts are the essential components of electric equipment. In the past, the silver-cadmium oxide is used as the materials contacts. However, because it generates the poison cadmium gas during the service, which causes the cancer, the silver-cadmium oxide will be prohibited in the near future. Now the silver-tin oxide is often used as the materials of the electrical contacts. To oxidize pure tin more easily,¡AIn2O3 is usually added as the auxiliary oxide agent. However, In2O3 is expensive. Hence, in this study, the other metal oxide agents are added to the silver-tin oxide to investigate the agent effect on the erosion characteristics (such as the erosion amount, the contact resistance, the arc energy, etc). This study uses the powder metallurgy to produce the electrical contacts, where the sizes of pure silver powder and tin oxide powder are 2~3£gm and 4~5£gm, respectively. The doping agents are made of 3~4£gm tungsten oxide and 3~5£gm molybdenum oxide, respectively. The powder are mixed in a suitable proportion to produce electrical contacts. The effect of metal oxide on the erosion of electrical contacts is investigated under different electric conditions. Results show that when the tin oxide powder is added to the pure sil-ver, the splashing of material can be prevented efficiently, and the erosion of electrical contacts can be reduced. Among the materials of silver-tin oxide, the contacts have the minimum erosion at the concen-tration of 5wt%. In order to reduce the cost of electrical con-tacts, the concentration of tin oxide is increased to 10wt% to investigate the influence of the doping agent. Results show that the addition of 0.3wt%WO3 has the minimum erosion. This electrical contact has lower erosion than the commercial ones. Furthermore, the regions, where the electrical contact has lower erosion than the commercial pure silver contacts and the silver-cadmium oxide, respectively, are established. These re-gions will be the best usable regions of silver tin oxide, and it will be the basis for the choice and the application of silver-tin oxide electrical contacts.

This thesis describes basic grammatical features and lexicon of Matal, a Chadic language spoken by around 18 000 people in northern Cameroon. A translation of the New Testament is used as a parallel text for the purposes of this study. The identified language structures are compared with other Chadic languages. The results show that Matal is overall typical for the language family, except for the pronominal system, which lacks a clusivity distinction. Nouns and adjectives have a limited morphology, only expressing number as a grammatical category, whereas verbs have many categories that are expressed morphologically, by prefixation and suffixation. For finite verb forms, subject prefixes are obligatory. Tense is expressed either by altered tone in the stem vowel or morphologically. Several verbal suffixes with number and person variants have been identified, although their functions have not been entirely clarified. A system of complex adpositions that make extensive use of grammaticalized body concepts has also been inquired, within which the phenomenon of preposition agreement has been identified. Basic syntactic features, such as word order, negation and topicalization are also addressed. The analysis of the lexicon demonstrates that the basic vocabulary is mainly inherited from earlier stages of the language, but a large number of lexical loans in various semantic domains have also entered Matal. / Denna uppsats beskriver grundläggande grammatiska drag och ordförråd i Matal, ett tchadspråk som talas av omkring 18 000 personer i norra Kamerun. En översättning av Nya Testamentet används som parallelltext i denna studie. Identifierade språkliga strukturer jämförs med andra tchadspråk. Resultaten visar att Matal är på det stora hela typiskt för språkfamiljen, med undantag för det pronominella systemet, som inte uppvisar någon skillnad i klusivitet. Substantiv och adjektiv har en begränsad morfologi som endast uttrycker numerus som grammatisk kategori, medan verb har ett stort antal kategorier som uttrycks morfologiskt. Dessa har formen av affix som fogas både före och efterstammen. I finita verbformer är subjektprefix obligatoriska. Tempus kan uttryckas antingen genom ändrad ton i stamvokalen eller morfologiskt. Ett antal verbsuffix med varianter för numerus och person har identifierats, dock har deras funktion inte klarlagts helt. Ett system med komplexa adpositioner som i stor utsträckning använder sig av grammatikaliserade kroppsdelstermer har också undersökts, inom vilket fenomenet av prepositionskongruens i vissa komplexa adpositioner har påvisats. Grundläggande syntaktiska drag som ordföljd, negation och topikalisering tas också upp. Analysen av Matals lexikon visar att det grundläggande ordförrådet är företrädesvis nedärvt från tidigare språkstadier, men också att ett stort antal lånord i olika semantiska domäner har kommit in i språket.