Peri-gondwanan permian correlations : the meso-tethyan margins

Correlations of the Permian sequences for sixteen regions of north eastern Gondwana during the Permian are presented in this review. These correlations are compared with Permian sequences of the Australian continent. Broad conclusions on palaeoclimatic change and tectonic events are summarised for six time intervals of the Permian Period.

The Asselian-Sakmarian-early Artinskian time interval indicates a change from cold to temperate depositional environments. Glacial deposits and low diversity Gondwanan marine faunas are succeeded by younger, warmer water, clastic and bioclastic sequences with moderately diverse marine faunas. Deposition of these sequences is occasionally associated with basaltic volcanism and initial rifting of the peripheral northern Gondwanan margin.

During the Late Artinskian-Kungurian (including Early Ufimian) time interval, climate amelioration occurred with the onset of carbonate deposition in several Cimmerian terranes. Basaltic volcanism in several terranes is indicative of significant rifting and the opening of the Meso-Tethys.

The Roadian (Late Ufimian) and Wordian-Capitanian (including Kazanian-Midian) time intervals were characterised by widespread, subtropical, marine carbonate depositional sequences. These occurred throughout the Cimmerian blocks as they drifted northward and on the more northerly parts of the Meso-Tethyan southern margin. These transgressive sequences may rest on significant unconformity surfaces. Equivalent carbonate units are known in the offshore and subsurface sequences of western Australia. Andesitic, convergent plate margin volcanism and volcaniclastic sequences are present in eastern Australia.

The Wuchiapingian time slice is characterised by widespread marine transgressions which extended into the north western basins of Australia.

The Changhsingian time slice is represented by relatively minor marine transgressive events in the Trans-Himalaya with the Selong section of Tibet being probably the most complete Permo-Triassic sequence for the southern margin of the Meso-Tethys.

A study of hydrogen bonding in concentrated diol/water solutions by proton NMR correlations with glass formation

Solute/water interactions in a series of diol solutions have been investigated by ¹H NMR. Strong hydrogen bonding between water and alcohols that are more basic than water is thought to result in lower chemical shifts of water protons compared to the case of pure water. This is attributed to a greater degree of covalent character in the hydrogen bonding between water and the more basic diols. The inductive effect of the methyl group and longer chain alkyls is observed to increase basicity in ethylene glycol, propylene glycol, and 2,3-butanediol solutions. A correlation between the glass-forming ability of the diol solutions and the stronger hydrogen-bonding solutes (i.e., stronger bases) is developed, with 2,3-butanediol best promoting glass formation at the lowest concentrations.

On the concept of ionicity in ionic liquids

Ionic liquids are liquids comprised totally of ions. However, not all of the ions present appear to be available to participate in conduction processes, to a degree that is dependent on the nature of the ionic liquid and its structure. There is much interest in quantifying and understanding this ‘degree of ionicity’ phenomenon. In this paper we present transport data for a range of ionic liquids and evaluate the data firstly in terms of the Walden plot as an approximate and readily accessible approach to estimating ionicity. An adjusted Walden plot that makes explicit allowance for differences in ion sizes is shown to be an improvement to this approach for the series of ionic liquids described. In some cases, where diffusion measurements are possible, it is feasible to directly quantify ionicity via the Nernst–Einstein equation, confirming the validity of the adjusted Walden plot approach. Some of the ionic liquids studied exhibit ionicity values very close to ideal; this is discussed in terms of a model of a highly associated liquid in which the ion correlations have similar impact on both the diffusive and conductive motions. Ionicity, as defined, is thus a useful measure of adherence to the Nernst–Einstein equation, but is not necessarily a measure of ion availability in the chemical sense.

An analysis of side chain interactions and pair correlations within antiparallel β-sheets : the differences between backbone hydrogen-bonded and non-hydrogen-bonded residue pairs

Cross-strand pair correlations are calculated for residue pairs in antiparallel β-sheet for two cases: pairs whose backbone atoms are hydrogen bonded together (H-bonded site) and pairs which are not (non-H-bonded site). The statistics show that this distinction is important. When glycine is located on the edge of a sheet, it shows a 3:1 preference for the H-bonded site. Thestrongest observed correlations are for pairs of disulfide-bonded cystines, many of which adopt a close-packed conformation with each cystine in a spiral conformation of opposite chirality to its partner. It is likely that these pairs are a signature for the family of small, cystine-rich proteins. Most other strong positive and negative correlations involve charged and polar residues. It appears that electrostatic compatibility is the strongest factor affecting pair correlation. Significant correlations are observed for β- and γ-branched residues inthe non-H-bonded site. An examination of the structures showsa directionality in side chain packing. There is a correlation between (1) the directionality in the packing interactions of non-H-bonded β- and γ-branched residue pairs, (2) the handedness of the observed enantiomers of chiral β-branched side chains, and (3) the handedness of the twist of β-sheet. These findings have implications for the formation of β-sheets during protein folding and the mechanism by which the sheet becomes twisted

Ripple effects of house prices : considering spatial correlations in geography and demography

Purpose: Studies into ripple effects have previously focused on the interconnections between house price movements across cities over space and time. These interconnections were widely investigated in previous research using vector autoregression models. However, the effects generated from spatial information could not be captured by conventional vector autoregression models. This research aimed to incorporate spatial lags into a vector autoregression model to illustrate spatial-temporal interconnections between house price movements across the Australian capital cities. Design/methodology/approach: Geographic and demographic correlations were captured by assessing geographic distances and demographic structures between each pair of cities, respectively. Development scales of the housing market were also used to adjust spatial weights. Impulse response functions based on the estimated SpVAR model were further carried out to illustrate the ripple effects. Findings: The results confirmed spatial correlations exist in housing price dynamics in the Australian capital cities. The spatial correlations are dependent more on the geographic rather than the demographic information. Originality/value: This research investigated the spatial heterogeneity and autocorrelations of regional house prices within the context of demographic and geographic information. A spatial vector autoregression model was developed based on the demographic and geographic distance. The temporal and spatial effects on house prices in Australian capital cities were then depicted.