She Shall Be Saved in Childbearing: Submission, Contemplation of Conception, and Annunciation Imagery in the Books of Hours of Two Late Medieval Noblewomen

The role of the Book of Hours in female lay devotional life during the late Middle Ages has been investigated and analyzed by many scholars and art historians over the course of the past century. The general consensus has been that semi-literate medieval women valued these books greatly as instructional manuals on how to attain salvation, using the images contained within as spiritual aids meant to encourage individual contemplation and pious recitation. Prayers for mediation, protection, and guidance featured prominently within these books and many historians of both genders have come to the conclusion that Books of Hours were a source of comfort and spiritual nourishment for women living in a male-dominated and male-oriented world. [excerpt

James R. Killian, Jr., Sputnik, and Eisenhower: White House Science Advice and the Reformation of American Science Education, 1955-1958

This paper chronicles the often-overlooked relationship between President Dwight D. Eisenhower and Dr. James R. Killian, Jr., the first-ever appointed Presidential Science Advisor. Emphasis is placed on the role of Dr. Killian and the President’s Science Advisory Committee (PSAC) in advocating curricular reform in the fields of science and mathematics, a reformation which became doubly important following the successful launch of the Soviet satellite Sputnik I in 1957. This essay examines the efforts of Eisenhower and Killian to keep pace with the Russian scientific advances by improving American education in the scientific and technical fields. It concludes with a discussion of the National Defense Education Act of 1958 and Killian’s efforts to see the piece of legislation enacted

The Metallacyclopentane-Olefin Interchange Reaction

Tris(triphenylphosphine)tetramethylenenickel(II) and biscyclopentadienyltetramethylenetitanium, prepared from the reaction of a 1,4-dilithiobutane and the transition metal dihalides react with olefins to produce substituted metallacyclopentanes; the stereochemistry and substitution pattern of the metallocycles formed from propene, octa-1,7-diene, and norbornadiene has been determined

\u3ci\u3eArcynopteryx Compacta\u3c/i\u3e (Plecoptera: Perlodidae), A Holarctic Stonefly Confirmed From Lake Superior, With a Review and First Checklist of the Stoneflies of Michigan

Arcynopteryx compacta, a northern Holarctic species, is confirmed from Lake Superior along the Keweenaw Peninsula of Michigan\u27s Upper Peninsula. A checklist of stoneflies of Michigan is provided, reporting 58 species plus a list of an additional 19 species that are likely to occur in the state

Chelated Ruthenium Catalysts for Z-Selective Olefin Metathesis

We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands that catalyze highly Z-selective olefin metathesis. A very simple and convenient procedure for the synthesis of such catalysts has been developed. Intramolecular C–H bond activation of the NHC ligand, promoted by anion ligand substitution, forms the appropriate chelate for stereocontrolled olefin metathesis

Facile Synthesis of Effcient and Selective Ruthenium Olefin Metathesis Catalysts with Sulfonate and Phosphate Ligands

A series of novel, air-stable ruthenium NHC catalysts with sulfonate and phosphate anions have been prepared easily in one pot at high yields using commercially available precursors. The catalysts were found to be effective for ring-opening metathesis polymerization, ring-closing metathesis, and cross-metathesis. The catalysts showed higher cis-selectivity in olefin cross-metathesis reactions as compared to earlier known ruthenium-based olefin metathesis catalysts, with allylbenzene and cis-1,4-diacetoxybutene as substrates

Formation of bridged bicycloalkenes via ring closing metathesis

Ring closing metathesis may be used in the formation of small ring bicycloalkenes from monocyclic diene precursors

Tandem ring-closing metathesis reaction with a ruthenium catalyst containing a N-heterocyclic ligand

The highly active catalyst 2 was used in tandem RCM to make molecules with various ring systems containing α,β-unsaturated carbonyl compounds

A catalytic cycle for oxidation of tert-butyl methyl ether by a double C−H activation-group transfer process

A square-planar, iridium(I) carbene complex is shown to effect atom and group transfer from nitrous oxide and organic azides, releasing the corresponding formate or formimidate and an iridium(I)−dinitrogen adduct. The dinitrogen complex performs C−H activation upon photolysis or thermolysis, regenerating the carbene from tert-butyl methyl ether with loss of H_2. Taken together, these reactions represent a net catalytic cycle for C−H functionalization by double C−H activation to generate metal−carbon multiple bonds. Additionally, the unusual group transfer from diazo reagents underscores the unique nature of the reactivity observed for nucleophilic-at-metal carbene complexes

Monotelechelic Poly(oxa)norbornenes by Ring-Opening Metathesis Polymerization Using Direct End-Capping and Cross-Metathesis

Two different methodologies for the synthesis of monotelechelic poly(oxa)norbornenes prepared by living ring-opening metathesis polymerization (ROMP) are presented. The first method, termed direct end-capping, is carried out by adding an internal cis-olefin terminating agent (TA) to the reaction mixture immediately after the completion of the living ROMP reaction. The second method relies on cross-metathesis (CM) between a methylene-terminated poly(oxa)norbornene and a cis-olefin TA mediated by the ruthenium olefin metathesis catalyst (H_(2)IMes)(Cl)_(2)Ru(CH-o-OiPrC_(6)H_4) (H_(2)IMes = 1,3-dimesitylimidazolidine-2-ylidene). TAs containing various functional groups, including alcohols, acetates, bromides, α-bromoesters, thioacetates, N-hydroxysuccinimidyl esters, and Boc-amines, as well as fluorescein and biotin groups, were synthesized and tested. The direct end-capping method typically resulted in >90% end-functionalization efficiency, while the CM method was nearly as effective for TAs without polar functional groups or significant steric bulk. End-functionalization efficiency values were determined by ^(1)H NMR spectroscopy