Investigation of the Solvent Enclathration Potentials of 5-Phenyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ol and Related Seven-membered Ring Alcohols

Four previously reported tricyclic alcohols containing seven-membered central B-rings, 5-phenyl-10, 11-dihydro-5Hdibenzo [a,d]cyclohepten-5-ol, 5-phenyl-5H-dibenzo[a,d]cyclohepten-5-ol, 11-phenyl-6, 11-dihydrodibenzo[b,e]oxepin-11-ol and 11-phenyl-6, 11-dihydrodibenzo[b,e]thiepin-11-ol have been synthesized and their solvent enclathration (inclusion) properties investigated and compared by using 1H-NMR and differential scanning calorimetry (DSC). The presence of an oxygen or a sulphur atom, respectively, in the B-ring of the latter two compounds had a detrimental effect on the solvent enclathration properties of the host compounds as compared to those containing an ethane or ethylene bridge. This suggests that, although enclathration is highly dependent on the hydrogen bonding ability of the host, rigidity of the structure plays a crucial role in the formation and stability of these complexes. South African Journal of Chemistry Vol.57 2004: 44-4

The Synthesis of Novel Enclathration Compounds : Bis(9-amino-9-aryl-9H-thioxanthenes) and Investigations of their Host-Guest Inclusion Potential

Four novel bis(9-amino-9-aryl-9H-thioxanthenes) were synthesized and their inclusion potential assessed by allowing them to crystallize slowly from organic solvents (single and binary mixtures). Only two of the compounds studied displayed inclusion ability and enclathrated several of the solvents studied. The stoichiometries of the resultant inclusion complexes were determined by 1H-NMRstudies, and the favoured host:guest ratios were found to be predominantly 1 : 1, with ratios 2 : 1, 4 : 3 and 3 : 2 occurring less frequently. The stability of the clathrate complexes has been investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Competition experiments were carried out with the compounds that successfully hosted solvent molecules in order to determine their relative affinity for these solvents. One of the hosts was also exposed to two vaporous guests in two separate experiments to assess its ability for entrapping molecules from the vapour phase. South African Journal of Chemistry Vol.55 2002: 144-14

(E)-N-(Ferrocenyl­methyl­idene)(pyridin-3-yl)methanamine

In the title compound, [Fe(C5H5)(C12H11N2)], the cyclo­penta­dienyl rings are present in an eclipsed conformation. The imine is E-configured. In the crystal, C—H⋯N inter­actions involving both N atoms connect the mol­ecules into two undulating sheets perpendicular to the b axis. The centroid–centroid distance between the two aromatic systems in the ferrocenyl moiety is 3.2928 (18) Å. A C–H⋯π inter­action is also present

Effects of current mismatch due to uneven soiling on the performance of multi-crystalline silicon module strings

Photovoltaic (PV) module operation is critical in PV systems for optimum generation of electrical power. Modules installed in the field suffer uneven soiling caused by bird droppings and dust build-up on their front surface. This study investigated the impact of partial shading caused by non-uniform soiling on the electrical characteristics of multi-crystalline silicon (mc-Si) modules and strings, and compared this with simulated I-V parameters. Light and heavy uneven soiling on mc-Si solar cells resulted in current mismatch which can be simulated. The effects of partial soiling on the I-V characteristics of mc-Si module strings were experimentally measured and agreed with the simulated results

DNA replication times the cell cycle and contributes to the mid-blastula transition in Drosophila embryos

Deletion of S phase disrupts mitotic timing in maternally regulated cycles, but it doesn't alter the cell cycle once zygotic transcription has begun

Theory, Simulation and Nanotechnological Applications of Adsorption on a Surface with Defects

Theory of adsorption on a surface with nanolocal defects is proposed. Two efficacy parameters of surface modification for nanotechnological purposes are introduced, where the modification is a creation of nanolocal artificial defects. The first parameter corresponds to applications where it is necessary to increase the concentration of certain particles on the modified surface. And the second one corresponds to the pattern transfer with the help of particle self-organization on the modified surface. The analytical expressions for both parameters are derived with the help of the thermodynamic and the kinetic approaches for two cases: jump diffusion and free motion of adsorbed particles over the surface. The possibility of selective adsorption of molecules is shown with the help of simulation of the adsorption of acetylene and benzene molecules in the pits on the graphite surface. The process of particle adsorption from the surface into the pit is theoretically studied by molecular dynamic technique. Some possible nanotechnological applications of adsorption on the surface with artificial defects are considered: fabrication of sensors for trace molecule detection, separation of isomers, and pattern transfer.Comment: 12 pages, 2 Postscript figures. Submitted to Surface Science (1998

2-Bromo-1-phenyl­ethanone

The title compound, C8H7BrO, is a halogenated derivative of acetophenone. The mol­ecule shows noncrystallographic Cs symmetry. The intra­cyclic C—C—C angles cover the range 118.8 (2)–120.4 (3)°. In the crystal structure, C—H⋯O contacts connect the mol­ecules into undulating sheets perpendicular to the crystallographic c axis

Influence of cyclin type and dose on mitotic entry and progression in the early Drosophila embryo

Cyclins are key cell cycle regulators, yet few analyses test their role in timing the events that they regulate. We used RNA interference and real-time visualization in embryos to define the events regulated by each of the three mitotic cyclins of Drosophila melanogaster, CycA, CycB, and CycB3. Each individual and pairwise knockdown results in distinct mitotic phenotypes. For example, mitosis without metaphase occurs upon knockdown of CycA and CycB. To separate the role of cyclin levels from the influences of cyclin type, we knocked down two cyclins and reduced the gene dose of the one remaining cyclin. This reduction did not prolong interphase but instead interrupted mitotic progression. Mitotic prophase chromosomes formed, centrosomes divided, and nuclei exited mitosis without executing later events. This prompt but curtailed mitosis shows that accumulation of cyclin function does not directly time mitotic entry in these early embryonic cycles and that cyclin function can be sufficient for some mitotic events although inadequate for others

1-(4-Ferrocenylphen­yl)-3-methyl­imidazolium iodide monohydrate

In the title compound, [Fe(C5H5)(C15H14N2)]I·H2O, the benzene and imidazolium rings are twisted by 17.26 (17) and 32.53 (19)°, respectively, with respect to the η5-C5H4 plane of the ferrocenyl unit. The imidazolium ring is rotated by 48.81 (17)° with respect to the benzene ring. The packing is dominated by layers established by O—H⋯I, C—H⋯I and C—H⋯O contacts and propagating along the bc plane

U–Pb (LA-ICP-MS) ages on detrital zircon grains from Angacos limestone siliciclastic levels (Caucete Group), San Juan province, Argentina: provenance implications for the Cuyania terrane

In this work, we present isotopic results on detrital zircon grains in siliciclastic levels from Angacos Limestone. This unit, together with the El Quemado, La Paz and El Desecho Formations, constitute the Caucete Group (Borrello, 1969; emend. Vujovich, 2003), which occurs on the western side of the Pie de Palo range in northwestern Argentina (Fig. 1). The Pie de Palo Complex is bordered by the Las Pirquitas Thrust and is characterized by Grenville-age basement with medium- to high-grade metamorphic and minor igneous rocks (Vujovich et al., 2004, and references therein). The Pie de Palo range is part of the Cuyania composite terrane (Ramos et al., 1998) and has been recognized as an allochthonous microcontinent derived from Laurentia or as paraautochthonous unit from Gondwana (Finney et al., 2005). The Angacos Limestone is mainly composed of limestone, calcareous schist, dolostone, and calcitic marble. The metamorphism indicates greenschist facies (Ramos and Vujovich, 2000). Moreover, mylonitic products of the high deformation that affected the entire zone are present. The protolith of these carbonates is interpreted as a succession of limestone and dolostone with minor sandstone interbeds. The age of the Angacos Limestone is uncertain because of the absence of diagnostic fossils. Isotopic studies of Sr, C and O has led to the correlation with the Early Paleozoic platform limestone sequence from the Precordillera (Linares et al., 1982; Galindo et al., 2004; Naipauer et al., 2005). It is important to note that the El Quemado Formation as a part of the Caucete Group has a maximum depositional age of 550 Ma as defined by detrital zircon data (Naipauer et al., 2005). The main purpose of this work is to present isotopic data of the detrital zircons separated from siliciclastic levels interlayered within the Angacos Limestone. We compare the obtained results with detrital zircon data from the El Quemado Formation (Naipauer et al., 2005; Ellis, 2005), and discuss some provenance implications in the tectonic terrane.Centro de Investigaciones GeológicasConsejo Nacional de Investigaciones Científicas y Técnica