65 research outputs found

    Chiroptical Properties and Conformation of 4,5-Saturated Derivatives of 5-Aryl-1,4-benzodiazepin-2-ones

    Get PDF
    CD spectra of a series of 5-aryl-7-chloro-l,3,4,5-tetrahydro- 2H-l,4-benzodiazepin-2-one derivatives having different substituents at positions 1, 3, 4, and 5 were studied. The absolute configuration at C-5 of two homochiral analogues, 1 and 2, having enantiomorphous ring conformations was determined on the basis of chiroptical correlations and theoretical calculations. The latter have shown that the optical activity mainly originates from the one-electron mechanism and is determined by the helicity of the diazepine ring, i. e. by the inherent chirality of the partial chromophore 4-chloro-N,2-dimethyl-formanilide. Exciton inter action s between transitions of the two arornatic chromophores A and C also give a significant contribution to chiroptical properties. By applying simple chiroptical rules dedueed from experimental spectra and supported by calculations, the stereochemistry (absolute conformation and configuration), of 3,5-disubstituted cis and trans epimeric pairs (7-17) was revealed

    CMIP5 Intermodel Relationships in the Baseline Southern Ocean Climate System and With Future Projections

    Get PDF
    This is the final version. Available on open access from Wiley via the DOI in this recordClimate models exhibit a broad range in the simulated properties of the climate system. In the early historical period, the absolute global mean surface air temperature in Coupled Model Intercomparison Project, phase 5 (CMIP5) models spans a range of ~12-15 °C. Other climate variables may be linked to global mean temperature, and so accurate representation of the baseline climate state is crucial for meaningful future climate projections. In CMIP5 baseline climate states, statistically significant intermodel correlations between Southern Ocean surface temperature, outgoing shortwave radiation, cloudiness, the position of the mid-latitude eddy-driven jet, and Antarctic sea ice area are found. The baseline temperature relationships extend to projected future changes in the same set of variables. The tendency for models with initially cooler Southern Ocean to exhibit more global warming, and vice versa for initially warmer models, is linked to baseline Southern Ocean climate system biases. Some of these intermodel correlations arise due to a ‘capacity for change’. For example, models with more sea ice initially have greater capacity to lose sea ice as the planet warms, whereas models with little sea ice initially are constrained in the amount they can lose. Similar constraints apply to Southern Ocean clouds, which are projected to reduce under radiative forcing, and the jet latitude, which is projected to migrate poleward. A first look at emerging data from CMIP6 reveals a shift of the relationship from the Southern Ocean towards the Antarctic region, possibly due to reductions in Southern Ocean biases, such westerly wind representation.Natural Environment Research Council (NERC)Centre for Southern Hemisphere Oceans ResearchAustralian Government National Environmental Science ProgramAustralian Research Council (ARC

    Chiroptical Properties and Conformation of 4,5-Saturated Derivatives of 5-Aryl-1,4-benzodiazepin-2-ones

    Get PDF
    CD spectra of a series of 5-aryl-7-chloro-l,3,4,5-tetrahydro- 2H-l,4-benzodiazepin-2-one derivatives having different substituents at positions 1, 3, 4, and 5 were studied. The absolute configuration at C-5 of two homochiral analogues, 1 and 2, having enantiomorphous ring conformations was determined on the basis of chiroptical correlations and theoretical calculations. The latter have shown that the optical activity mainly originates from the one-electron mechanism and is determined by the helicity of the diazepine ring, i. e. by the inherent chirality of the partial chromophore 4-chloro-N,2-dimethyl-formanilide. Exciton inter action s between transitions of the two arornatic chromophores A and C also give a significant contribution to chiroptical properties. By applying simple chiroptical rules dedueed from experimental spectra and supported by calculations, the stereochemistry (absolute conformation and configuration), of 3,5-disubstituted cis and trans epimeric pairs (7-17) was revealed

    Kondisi Self Disclosure Mahasiswa Bimbingan dan Konseling

    Get PDF
    <p>Penelitian ini bertujuan untuk mengidentifikasikan kondisi <em>self disclosure</em> mahasiswa Bimbingan dan Konseling berdasarkan dimensi keluasan dan kedalaman. Jenis penelitian ini adalah penelitian deskriptif<em> </em>dengan metode kuantitatif. Instrumen yang digunakan adalah Inventori Pengukuran <em>Self Disclosure</em> Mahasiswa (IPSDM), dengan Sampel sebanyak 85 orang mahasiswa menggunakan teknik <em>Simple Random Sampling</em>. Temuan penelitian mengungkapkan bahwa, 1) Sebanyak 55,29% mahasiswa Bimbingan dan Konseling memiliki kondisi keluasan<em> self disclosure</em> pada kategori tidak luas dan dilihat pada target <em>person </em> menunjukkan bahwa ibu merupakan target <em>person</em> pertama dan paling banyak dipilih responden penelitian (72,16%), 2) Sebanyak 38,82% mahasiswa Bimbingan dan Konseling memiliki kondisi kedalaman<em> self disclosure</em> pada kategori sedang. Penelitian ini merekomendasikan mahasiswa Bimbingan dan Konseling, agar dapat memperluas dan memperdalam kemampuan melakukan <em>self disclosure</em> dan perlu pelayanan Bimbingan dan Konseling untuk memperluas dan memperdalam kemampuan dalam melakukan <em>self disclosure</em>.</p

    Impacts of marine heatwaves on tropical western and central Pacific Island nations and their communities

    No full text
    Marine heatwaves can have devastating impacts on marine species and habitats, often with flow-on effects to human communities and livelihoods. This is of particular importance to Pacific Island countries that rely heavily on coastal and ocean resources, and for which projected increases in future marine heatwave (MHW) frequency, intensity, and duration could be detrimental across the Pacific Island region. In this study, we investigate MHWs in the tropical western and central Pacific Ocean region, focusing on observed MHWs, their associated impacts, and future projections using Coupled Model Intercomparison Project phase 6 (CMIP6) simulations under a low (SSP1–2.6) and a high (SSP5–8.5) greenhouse gas emissions scenario. Documented impacts from “Moderate” mean intensity MHW events in Fiji, Samoa, and Palau, that were categorised as “Strong” at their peak, included fish and invertebrate mortality and coral bleaching. Based on CMIP6 multi-model mean estimates, and relative to current baselines, “Moderate” intensity MHWs are projected to increase from recent historical (1995–2014) values of 10–50 days per year (dpy) across the region to the equivalent of >100 dpy by the year 2050 under the low emissions scenario, and > 200 dpy nearer the equator. Under the high emissions scenario, 200 dpy of Moderate MHW intensities are projected across most of the region by 2050, with >300 dpy nearer the equator. For the most intense “Extreme” category of MHW, estimates range from 50 dpy projected under the high emissions scenario by 2050. In contrast, “Extreme” MHWs are projected to increase to <5 dpy by 2050 under the low emissions scenario, highlighting the importance for Pacific Island nations that global emissions more closely follow the low emissions scenario trajectory

    DICOBALT HEXACARBONYL DERIVATIVES OF CHIRAL ACETYLENES

    No full text
    (mu(2)-RC(2)R')Co-2(CO)(6) complexes are prepared where R not equal R' and one of these substituents is a chiral organic group. The structures of the 11 complexes (10 new) range from the simplest possible chiral acetylenic hydrocarbon derivative (S-3-methyl-1-pentyne 1a) to ethynylsteroid (1f, 1g, 1h) and ethynylcodeine (1i, 1j, 1k) derivatives. The CD spectra are reported and the results are analysed in terms of a quadrant rule. The CD spectra show that in all complexes the Co-2(CO)(6) fragment of the molecule gets chirally perturbed. The reasons for the chiral perturbation include apolar repulsing (dominant for the hydrocarbon acetylenes) and polar attractive (''autosolvation''; dominant for acetylenes with polar hetero-atom containing substituents) forces
    corecore