Australian Nuclear Science and Technology Organisation

SciPy is an open-source scientific computing library for the Python programming language. Since its initial release in 2001, SciPy has become a de facto standard for leveraging scientific algorithms in Python, with over 600 unique code contributors, thousands of dependent packages, over 100,000 dependent repositories and millions of downloads per year. In this work, we provide an overview of the capabilities and development practices of SciPy 1.0 and highlight some recent technical developments.

Abstract: SciPy is an open-source scientific computing library for the Python programming language. Since its initial release in 2001, SciPy has become a de facto standard for leveraging scientific algorithms in Python, with over 600 unique code contributors, thousands of dependent packages, over 100,000 dependent repositories and millions of downloads per year. In this work, we provide an overview of the capabilities and development practices of SciPy 1.0 and highlight some recent technical developments.

The energy costs associated with large-scale industrial separation of light hydrocarbons by cryogenic distillation could potentially be lowered through development of selective solid adsorbents that operate at higher temperatures. Here, the metal-organic framework Fe(2)(dobdc) (dobdc(4-) : 2,5-dioxido-1,4-benzenedicarboxylate) is demonstrated to exhibit excellent performance characteristics for separation of ethylene/ethane and propylene/propane mixtures at 318 kelvin. Breakthrough data obtained for these mixtures provide experimental validation of simulations, which in turn predict high selectivities and capacities of this material for the fractionation of methane/ethane/ethylene/acetylene mixtures, removal of acetylene impurities from ethylene, and membrane-based olefin/paraffin separations. Neutron powder diffraction data confirm a side-on coordination of acetylene, ethylene, and propylene at the iron(II) centers, while also providing solid-state structural characterization of the much weaker interactions of ethane and propane with the metal.

The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correlations in the offset.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

ABSTRACT Early researchers of radiocarbon levels in Southern Hemisphere tree rings identified a variable North-South hemispheric offset, necessitating construction of a separate radiocarbon calibration curve for the South. We present here SHCal20, a revised calibration curve from 0–55,000 cal BP, based upon SHCal13 and fortified by the addition of 14 new tree-ring data sets in the 2140–0, 3520–3453, 3608–3590 and 13,140–11,375 cal BP time intervals. We detail the statistical approaches used for curve construction and present recommendations for the use of the Northern Hemisphere curve (IntCal20), the Southern Hemisphere curve (SHCal20) and suggest where application of an equal mixture of the curves might be more appropriate. Using our Bayesian spline with errors-in-variables methodology, and based upon a comparison of Southern Hemisphere tree-ring data compared with contemporaneous Northern Hemisphere data, we estimate the mean Southern Hemisphere offset to be 36 ± 27 14 C yrs older.

Metal oxide nanoparticles are finding increasing application in various commercial products, leading to concerns for their environmental fate and potential toxicity. It is generally assumed that nanoparticles will persist as small particles in aquatic systems and that their bioavailability could be significantly greater than that of larger particles. The current study using nanoparticulate ZnO (ca. 30 nm) has shown that this is not always so. Particle characterization using transmission electron microscopy and dynamic light scattering techniques showed that particle aggregation is significant in a freshwater system, resulting in flocs ranging from several hundred nanometers to several microns. Chemical investigations using equilibrium dialysis demonstrated rapid dissolution of ZnO nanoparticles in a freshwater medium (pH 7.6), with a saturation solubility in the milligram per liter range, similar to that of bulk ZnO. Toxicity experiments using the freshwater alga Pseudokirchneriella subcapitata revealed comparable toxicity for nanoparticulate ZnO, bulk ZnO, and ZnCl2, with a 72-h IC50 value near 60 microg Zn/ L, attributable solely to dissolved zinc. Care therefore needs to be taken in toxicity testing in ascribing toxicity to nanoparticles per se when the effects may be related, at least in part, to simple solubility.

The contrast-variation technique is employed in multiple-contrast neutron/X-ray reflectometry experiments to highlight scattering from different structural components that are present at a surface or interface. The advantage of this technique is that the structural model used to describe the interfacial scattering length density profile must apply to all the contrasts measured. A new reflectivity analysis package, MOTOFIT , which runs in the IGOR Pro environment (http://www.wavemetrics.com), has been created to aid the simultaneous fitting (with the same structural model) of these multiple-contrast data, using an intuitive graphical user interface, which most co-refinement packages do not possess. MOTOFIT uses a slab-model approach with the Abeles matrix method, and extensions for surface roughness to perform non-linear least-squares regression on the experimental reflectivity curves. Other features, such as the ability to create complicated interparameter constraints or analyse reflectivity from multilayers, simulated annealing, etc. , make MOTOFIT a powerful reflectometry analysis package

Abstract The status of room‐temperature potassium‐ion batteries is reviewed in light of recent concerns regarding the rising cost of lithium and the fact that room‐temperature sodium‐ion batteries have yet to be commercialised thus far. Initial reports of potassium‐ion cells appear promising given the infancy of the research area. This review presents not only an overview of the current potassium‐ion battery literature, but also attempts to provide context by describing previous developments in lithium‐ion and sodium‐ion batteries and the electrochemical reaction mechanisms discovered thus far. Perspectives and directions on the techniques available to characterize newly developed battery materials are also provided based on our experience and knowledge from the literature. It is hoped that through this review, the potential of potassium‐ion batteries as a competitive energy‐storage technology will be realised, and the accessibility and available knowledge of the techniques required to develop the technology will be made apparent.

We present a compilation of tropospheric 14 CO 2 for the period 1950–2010, based on published radiocarbon data from selected records of atmospheric CO 2 sampling and tree-ring series. This compilation is a new version of the compilation by Hua and Barbetti (2004) and consists of yearly summer data sets for zonal, hemispheric, and global levels of atmospheric 14 C. In addition, compiled (and extended) monthly data sets for 5 atmospheric zones (3 in the Northern Hemisphere and 2 in the Southern Hemisphere) are reported. The annual data sets are for use in regional and global carbon model calculations, while the extended monthly data sets serve as calibration curves for 14 C dating of recent, short-lived terrestrial organic materials.

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 +/- 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (-2.3 +/- 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.

Abstract In recent decades, significant advances in drug‐delivery systems have enabled more effective drug administration. To deliver drugs to specific organs, a range of organic systems (e.g., micelles, liposomes, and polymeric nanoparticles) have been designed. They suffer from limitations, including poor thermal and chemical stability, and rapid elimination by the immune system. In contrast, silica particles offer a biocompatible, stable, and “stealthy” alternative. Bioactive molecules can be easily encapsulated within silica particles by combining sol–gel polymerization with either spray‐drying or emulsion chemistry. Spray‐drying faces challenges, including low yield, surface segregation, and size limitations. In contrast, sol–gel emulsions enable the production of nanoparticles with homogeneous drug distribution, and permit ambient temperature processing, necessary for handling biologicals. Independent control of the size and release rate can be readily achieved. Preliminary in‐vivo experiments reveal enhanced blood stability of the nanoparticles, which, coupled with sustained release of anti‐tumor agents, show good potential for cancer treatment.

A worldwide compilation of atmospheric total phosphorus (TP) and phosphate (PO 4 ) concentration and deposition flux observations are combined with transport model simulations to derive the global distribution of concentrations and deposition fluxes of TP and PO 4 . Our results suggest that mineral aerosols are the dominant source of TP on a global scale (82%), with primary biogenic particles (12%) and combustion sources (5%) important in nondusty regions. Globally averaged anthropogenic inputs are estimated to be ∼5 and 15% for TP and PO 4 , respectively, and may contribute as much as 50% to the deposition over the oligotrophic ocean where productivity may be phosphorus‐limited. There is a net loss of TP from many (but not all) land ecosystems and a net gain of TP by the oceans (560 Gg P a −1 ). More measurements of atmospheric TP and PO 4 will assist in reducing uncertainties in our understanding of the role that atmospheric phosphorus may play in global biogeochemistry.

Poor cell adhesion to orthopaedic and dental implants may result in implant failure. Cellular adhesion to biomaterial surfaces primarily is mediated by integrins, which act as signal transduction and adhesion proteins. Because integrin function depends on divalent cations, we investigated the effect of magnesium ions modified bioceramic substrata (Al(2)O(3)-Mg(2+)) on human bone-derived cell (HBDC) adhesion, integrin expression, and activation of intracellular signalling molecules. Immunohistochemistry, flow cytometry, cell adhesion, cell adhesion blocking, and Western blotting assays were used. Our findings demonstrated that adhesion of HBDC to Al(2)O(3)-Mg(2+) was increased compared to on the Mg(2+)-free Al(2)O(3). Furthermore, HBDC adhesion decreased significantly when the fibronectin receptor alpha5beta1- and beta1-integrins were blocked by functional blocking antibodies. HBDC grown on the Mg(2+)-modified bioceramic expressed significantly enhanced levels of beta1-, alpha5beta1-, and alpha3beta1-integrins receptors compared to those grown on the native unmodified Al(2)O(3). Tyrosine phosphorylation of intracellular integrin-dependent signalling proteins as well as the expression of key signalling protein Shc isoforms (p46, p52, p66), focal adhesion kinase, and extracellular matrix protein collagen type I were significantly enhanced when HBDC were grown on Al(2)O(3)-Mg(2+) compared to the native Al(2)O(3). We conclude that cell adhesion to biomaterial surfaces is probably mediated by alpha5beta1- and beta1-integrin. Cation-promoted cell adhesion depends on 5beta1- and beta1-integrins associated signal transduction pathways involving the key signalling protein Shc and results also in enhanced gene expression of extracellular matrix proteins. Therefore, Mg(2+) supplementation of bioceramic substrata may be a promising way to improve integration of implants in orthopaedic and dental surgery.

Understanding the temporal variation of cosmic radiation and solar activity during the Holocene is essential for studies of the solar-terrestrial relationship. Cosmic-ray produced radionuclides, such as (10)Be and (14)C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia. Although records from different archives basically agree, they also show some deviations during certain periods. So far most reconstructions were based on only one single radionuclide record, which makes detection and correction of these deviations impossible. Here we combine different (10)Be ice core records from Greenland and Antarctica with the global (14)C tree ring record using principal component analysis. This approach is only possible due to a new high-resolution (10)Be record from Dronning Maud Land obtained within the European Project for Ice Coring in Antarctica in Antarctica. The new cosmic radiation record enables us to derive total solar irradiance, which is then used as a proxy of solar activity to identify the solar imprint in an Asian climate record. Though generally the agreement between solar forcing and Asian climate is good, there are also periods without any coherence, pointing to other forcings like volcanoes and greenhouse gases and their corresponding feedbacks. The newly derived records have the potential to improve our understanding of the solar dynamics and to quantify the solar influence on climate.

New measurements of atmospheric greenhouse gas concentrations in ice from Law Dome, Antarctica reproduce published Law Dome CO 2 and CH 4 records, extend them back to 2000 years BP, and include N 2 O. They have very high air age resolution, data density and measurement precision. Firn air measurements span the past 65 years and overlap with the ice core and direct atmospheric observations. Major increases in CO 2 , CH 4 and N 2 O concentrations during the past 200 years followed a period of relative stability beforehand. Decadal variations during the industrial period include the stabilization of CO 2 and slowing of CH 4 and N 2 O growth in the 1940s and 1950s. Variations of up to 10 ppm CO 2 , 40 ppb CH 4 and 10 ppb N 2 O occurred throughout the preindustrial period. Methane concentrations grew by 100 ppb from AD 0 to 1800, possibly due to early anthropogenic emissions.

Atmospheric inputs of iron to the open ocean are hypothesized to modulate ocean biogeochemistry. This review presents an integration of available observations of atmospheric iron and iron deposition, and also covers bioavailable iron distributions. Methods for estimating temporal variability in ocean deposition over the recent past are reviewed. Desert dust iron is estimated to represent 95% of the global atmospheric iron cycle, and combustion sources of iron are responsible for the remaining 5%. Humans may be significantly perturbing desert dust (up to 50%). The sources of bioavailable iron are less well understood than those of iron, partly because we do not know what speciation of the iron is bioavailable. Bioavailable iron can derive from atmospheric processing of relatively insoluble desert dust iron or from direct emissions of soluble iron from combustion sources. These results imply that humans could be substantially impacting iron and bioavailable iron deposition to ocean regions, but there are large uncertainties in our understanding.

Abstract A peak fitting procedure has been implemented for calculating crystallinity in granular starches. This methodology, widely used for synthetic polymers, is proposed to better reflect the crystalline content of starches than the method normally used, in which it is assumed that relatively perfect crystalline domains are interspersed with amorphous regions. The new approach takes into account irregularities in crystals that are expected to exist in semicrystalline materials. Therefore, instead of assuming that the amorphous background extends up to the base of diffraction peaks, the whole X‐ray diffraction (XRD) profile is fitted to an amorphous halo and several discrete crystalline diffraction peaks. The crystallinity values obtained from the XRD patterns of a wide range of native starches using this fitting technique are very similar to the double helix contents as measured by 13 C solid state NMR, suggesting that double helices in granular starches are present within irregular crystals. This contrasts with previous descriptions of crystalline and noncrystalline double helices that were based on the analysis of XRD profiles as perfect crystals interspersed in a noncrystalline background. Furthermore, with this fitting methodology it is possible to calculate the contribution from the different crystal polymorphs of starch to the total crystallinity. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 761–768, 2008. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

A major challenge for organic solar cell (OSC) research is how to minimize the tradeoff between voltage loss and charge generation. In early 2019, we reported a non-fullerene acceptor (named Y6) that can simultaneously achieve high external quantum efficiency and low voltage loss for OSC. Here, we use a combination of experimental and theoretical modeling to reveal the structure-property-performance relationships of this state-of-the-art OSC system. We find that the distinctive π-π molecular packing of Y6 not only exists in molecular single crystals but also in thin films. Importantly, such molecular packing leads to (i) the formation of delocalized and emissive excitons that enable small non-radiative voltage loss, and (ii) delocalization of electron wavefunctions at donor/acceptor interfaces that significantly reduces the Coulomb attraction between interfacial electron-hole pairs. These properties are critical in enabling highly efficient charge generation in OSC systems with negligible donor-acceptor energy offset.

The quantitative imaging of a phase object using 16 keV x rays is reported. The theoretical basis of the techniques is presented along with its implementation using a synchrotron x-ray source. We find that our phase image is in quantitative agreement with independent measurements of the object.