Skeletal Isomerization of n-Butene

In this review, the most relevant aspects of skeletal isomerization of n-butene to isobutene are discussed: the nature of the active sites, the prevailing mechanism of the skeletal isomerization, and the relation of this to that of n-butane. It is concluded that the prevailing mechanism of skeletal isomerization of n-butene is monomolecular (in contrast to butane isomerization) and requires Br?nsted acid (OH) active sites. The selectivity and catalytic stability can be influenced by the shape selectivity of zeolites and zeotypes. These effects are explained on the basis of the knowledge on the prevailing mechanism.     

One-phonon resonant Raman scattering in AlxGa1-xAs (0.5

C Trallero-Giner  A Cantarero  M Cardona  VI Gavrilenko 《Canadian Metallurgical Quarterly》1990,42(18):11875-11880

Formation of a resting form of Bacillus cereus and Micrococcus luteus

Under certain cultivation conditions, the bacteria Bacillus cereus and Micrococcus luteus form cystlike refractive cells (up to 60% of the total number) that retain viability over a long time, are metabolically inactive and thermotolerant and possess specific ultrastructure. These properties allow them to be attributed to a new type of resting forms of microorganisms.     

The emergence of silent myocardial ischemia as the manifestation of the nitrate withdrawal syndrome in patients with ischemic heart disease

A patient is described, who was examined 1 year after surgery for mandibular cyst diagnosed as radicular near the !5 tooth and for plasty of the secondary osseous cavity with hydroxyapatite granulate. X-Ray examination revealed a cystic cavity near the roots of teeth !234. Histologic examination of tissue fragments and the remainder of hydroxyapatite granulate, obtained by cystectomy, helped diagnose a primordial cyst. Intensive bone regeneration was observed at the site of hydroxyapatite granule accumulation and fusion of the new bone with the granules to form a solid osseogranular complex. The authors recommend hydroxyapatite ceramic granules for surgical treatment of minor and medium bone defects and for corrective bone plasty.