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Characterizing black carbon in rain and ice cores using coupled tangential flow filtration and transmission electron microscopy
Get PDFAntarctic ice cores have been used to study the history of black carbon (BC), but little is known with regards to the physical and chemical characteristics of these particles in the remote atmosphere. Characterization remains limited by ultra-trace concentrations in ice core samples and the lack of adequate methods to isolate the particles unaltered from the melt water. To investigate the physical and chemical characteristics of these particles, we have developed a tangential flow filtration (TFF) method combined with transmission electron microscopy (TEM). Tests using ultrapure water and polystyrene latex particle standards resulted in excellent blanks and significant particle recovery. This approach has been applied to melt water from Antarctic ice cores as well as tropical rain from Darwin, Australia with successful results: TEM analysis revealed a variety of BC particle morphologies, insoluble coatings, and the attachment of BC to mineral dust particles. The TFF-based concentration of these particles has proven to give excellent results for TEM studies of BC particles in Antarctic ice cores and can be used for future studies of insoluble aerosols in rainwater and ice core samples. © Author(s
Reversible hydrophobic to hydrophilic transition in graphene via water splitting induced by UV irradiation
No full textAlthough the reversible wettability transition between hydrophobic and hydrophilic graphene under ultraviolet (UV) irradiation has been observed, the mechanism for this phenomenon remains unclear. In this work, experimental and theoretical investigations demonstrate that the H2O molecules are split into hydrogen and hydroxyl radicals, which are then captured by the graphene surface through chemical binding in an ambient environment under UV irradiation. The dissociative adsorption of H2O molecules induces the wettability transition in graphene from hydrophobic to hydrophilic. Our discovery may hold promise for the potential application of graphene in water splitting. © 2014, Macmillan Publishers Limite
[18F]Radiochemistry using the nano tek microfluidic synthesis system
No full textThe use of continuous-flow microfluidics in radiochemistry has only emerged in recent
years.[1,2] Microfluidic devices feature channels with internal diameters of 10–300 mm, which process fluids with high speed and precision, resulting in improved mixing
efficiency. Other advantages of microfluidic technology include shorter reaction times,
greater radiochemical yield (RCY), and reduced consumption of reagents.[3] Recently,
the first account of a positron emission tomography (PET) radiotracer for human use
produced on a batch-mode microfluidics system was reported.[4] Currently, the most
employed commercial microfluidic system in radiochemistry is the NanoTek Microfluidic
Synthesis System manufactured by Advion[5] (Fig. 1) and its components and
method of operation have been described in detail previously.[6] Although the system
has been applied to radiochemical syntheses using radioisotopes such as carbon-11,[7]
nitrogen-13,[8] and technetium-99m,[9] the overwhelming majority of research using
the NanoTek system has been directed towards fluorine-18 (18F, t1/2¼109.7 min)
radiochemistry. Some recent, noteworthy examples are highlighted below and their
results compared with conventional radiochemical methods. © 2013 CSIRO Publishin
High-pH inclined stress corrosion cracking in Australian and Canadian gas pipeline X65 steels
No full textHigh-pH stress corrosion cracking is a form of environmental degradation of gas pipeline steels. The crack path is intergranular by nature and typically perpendicular to the maximum applied (hoop) stress (i.e. perpendicular to the pipe outer surface). Some unusual instances of cracks have been observed in Canadian and Australian X65 pipes, where cracks grow away from the perpendicular for considerable distances. This paper presents a comparative study in terms of crack morphology, mechanical properties and crystallographic texture for these Australian and Canadian pipe steels. It is shown that the crack morphologies are quite similar, the main difference being the angle at which the cracks propagate into the material. This difference could be explained by the different through-wall texture and grain aspect ratio measured in the two materials. The interdependency of crack tip plasticity, crack tip electrochemistry and anisotropy in microstructural texture seems to heavily affect the resulting inclined crack path. © 2016 Taylor & Franci
The impact of structural variation in simple lanthanide binding peptides
No full textA series of di-, tri- and tetra-peptides were synthesised using L- and D-glutamic acid in order to determine the effects of peptide length and stereochemistry on lanthanide binding affinity. Binding studies with Eu were performed at neutral pH, which is relevant to biological applications, and also under industrially relevant acidic conditions. Increasing peptide length resulted in higher binding affinity but the effect of stereochemistry was dependent on the peptide length. Modelling and experimental characterisation of the peptide[thin space (1/6-em)]:[thin space (1/6-em)]Eu complexes formed suggested that multiple modes of binding were present, with the Eu cation coordinated by the terminal and side chain carboxylic acids of the peptides as well as by backbone carbonyl groups. The peptide with the strongest binding affinity was the tetra-peptide with alternating L- and D-glutamic acid residues, which was able to bind Eu at pH values as low as 4. This peptide was appended with a long-chain alkene and used to covalently functionalise titania nanoparticles. The resulting peptide functionalised titania demonstrated selective sorption of lanthanides over Ca, Ni, Sr and Cs ions. Overall, a deeper understanding of how peptide structure affects lanthanide binding affinity has been gained and the potential of these peptides as selective ligands for separations at acidic pH has been demonstrated. © 2016 The Royal Society of Chemistr
The influence of constitutive material models on accumulated plastic strain in finite element weld analyses
No full textRecent studies in computational weld mechanics have revealed the importance of the material plasticity model when predicting weld residual stresses. The present work seeks to extend this level of understanding to include the effects of the assumed material annealing behaviour, particularly when modelling multi-pass welds that comprise several thermo-mechanical loading cycles. A series of numerical analyses are performed to examine the variability in predicted residual stress profiles for different material models, using a validated finite element model for a three-pass slot weld in AISI 316LN austenitic steel. The material models consider both the work hardening and annealing assumptions for the chosen material. Model sensitivity is established not only from a weld residual stress perspective, but also from an assessment of the post-weld plastic strain accumulated in the weldment. Predictions are compared with indirect measurements acquired using cross-weld micro-hardness maps taken from benchmark specimens. Sensitivity studies reveal that the choice of annealing behaviour will have a significant impact on plastic flow predictions, which is dependent on the annealing temperature specified. Annealing assumptions will have a varying impact on the weld residual stress predictions, such that the extent of sensitivity is dependent on the plasticity model chosen. In contrast, the choice of plasticity model will have a significant effect on the predicted weld residual stresses, but relatively little effect on predictions of equivalent plastic strain. © 2015 Elsevier Ltd
Cytotoxicity and Structural Analyses of 2,2′‐Bipyridine‐, 4,4′‐Dimethyl‐2,2′‐bipyridine‐ and 2‐(2′‐Pyridyl)quinoxalineplatinum(II) Complexes
No full textPlatinum anticancer complexes incorporating 2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (44Me2bpy) or 2-(2′-pyridyl)quinoxaline (2pq) as polyaromatic ligands and the S,S or R,R isomer of 1,2-diaminocyclohexane as ancillary ligands in the form [Pt(PL)(AL)]2+ have been synthesised and characterised. X-ray diffraction was used to elucidate the structure and stacking behaviour of the complexes, revealing interesting properties that may impact their biological activity. Pulsed gradient spin-echo NMR experiments elucidated the aggregation behaviour of these complexes in solution. The cytotoxicity of each complex was assessed against the L1210 murine leukaemia, HT29 human colon carcinoma and U87 human glioblastoma cell lines and compared to other complexes within this class. The complexes incorporating 44Me2bpy were found to be the most potent at inhibiting cell growth with IC50 values for the S,S isomer (0.13–0.5 μM) less than that for cisplatin (0.36–11 μM), oxaliplatin (0.9–1.8 μM) or carboplatin (>50 μM). Most complexes were found to be very effective against HT29 colon carcinoma cells. © 1999-2020 John Wiley & Sons, Inc
Strontium mineralization of shark vertebrae
Get PDFDetermining the age of sharks using vertebral banding is a vital component of management, but the causes of banding are not fully understood. Traditional shark ageing is based on fish otolith ageing methods where growth bands are assumed to result from varied seasonal calcification rates. Here we investigate these assumptions by mapping elemental distribution within the growth bands of vertebrae from six species of sharks representing four different taxonomic orders using scanning x-ray fluorescence microscopy. Traditional visual growth bands, determined with light microscopy, were more closely correlated to strontium than calcium in all species tested. Elemental distributions suggest that vertebral strontium bands may be related to environmental variations in salinity. These results highlight the requirement for a better understanding of shark movements, and their influence on vertebral development, if confidence in age estimates is to be improved. Analysis of shark vertebrae using similar strontium-focused elemental techniques, once validated for a given species, may allow more successful estimations of age on individuals with few or no visible vertebral bands. © 2016 Macmillan Publishers Limite
Cave lion skeleton from the Maly Anyuy River (Chukotka, Russia)
No full textCave lion (Panthera spelaea) remains, like skeletons, skulls
and individual bones, have been discovered all over the
mammoth fauna range from Iberian Peninsula to North
America. In Russia these 6nds are scattered and seldom.
In summer 2008 a compact cluster of cave lion remains
belonging to a single specimen, a tuft of visually unidenti6ed
ginger-coloured hair and a horse vertebra were found in the
water under the bank outcrop of Maly Anuy River (68.18 N,
161.44 E), Chukotka, Russia. The 6nd included 36 vertebrae,
20 ribs, limbs bones: scapula, humerus, pelvic, femur, tibia,
6bula, patellae, talus, metatarsal, and third phalanx with
cover. In 2009 on the same spot the cave lion mandibular
bones were found. Their age, sex and features support
the probability of belonging to the same specimen as the
skeleton prior. Bone sizes (mandible length: 255.7-262.0
mm; P3-M1 mean alveolar length: 80.2 mm; mean LxB of M1:
29.5x14.9 mm; M1 mean height (buccal): 53.5 mm; length of
humerus: 386.1 mm, of femur: 431.5 mm, of tibia: 362.0 mm)
fell within the range of other cave lion 6nds.
Some bones display deformities and age-related changes,
e.g. an asymmetry of thoracic and sacral vertebrae, a notch
on the scapula, sclerotized ligaments on the femur and tibia,
osteophytes on the ribs. Vertebrae asymmetry is probably a
result of young age trauma. Sclerotized ligaments are likely
a sign of myositis – common for musculoskeletal overloads.
The mandibles bear traces of age-related changes and
pathological cortex transformation due to periostitis,
usually from traumatic injuries. The noted features are not
a sign of systemic illness though. The bone cortex, apart
from the mandible outer surface, is dense and healthy; joint
surfaces show no traces of degradation; muscle origins
and insertions are clearly pronounced on the bones that
testi6es a high motor activity of the animal. The skeleton
evidently belonged to a mature but not old male. The age,
from counting the annual layers in canine cementum, was
about 12 years. The claw sheath on the third phalanx and
fur sample are of particular interest, since the cave lion skin
derivatives have not been discovered previously.
Stable isotope analyses of samples taken from a few
bones, fur and claw sheath of the 6nds were done to check
the possible diet of the animal and specimens identity.
The results compared with 6ve more specimens of cave
lion and some representatives of mammoth fauna from
Chukchi and Yakut territories, namely mammoth, woolly
rhinoceros, bison, horse, two species of deer, bighorn
sheep and wolf (all samples from the Ice Age Museum,
Moscow). The isotopic signature of the Anuy lion remains
testi6es that all of them nearly certainly came from the
same individual, yet the mandible slightly di?ers from the
rest. Stable isotope studies for this cave lion also de6ne
that the main prey included Bison, Equus and Ovibos.
Notably, reindeer (Rangifer tarandus) was not among its
most probable prey. The obtained stable isotope results for
the found lion remains and its potential diet deviate from
these for Western Europe, where reindeer remained the
main food source (Bocherens et al., 2011). This deviation
can be explained by relatively smaller reindeer population
in the Asian North-East compared to the other available
ungulate prey.
The tuft of fur found near the cave lion’s remains has good
di?erentiation: guard hair (I–IV categories) (GH) and woolly
hair (I–II categories) (WH). GH colour varies from light-yellow
to dark-brown, without a black tip. WH is light-yellow or
whitish. GH type I are typical primary hairs, which, judging
by their fragments of length up to 50 mm, are long, thick
(up to 200 μm), strong and smooth. The shape of shaft at
the base is cylindrical, but in the middle one side :attens a
little. The medulla is well-developed, occupies up to 80% of
the shaft diameter and runs through its middle. GH of other
categories are thinner (45–90 μm) and have medulla less
developed. WH are long, with 3–6 bends looking like elastic
springs. In the bends the medulla is shifted in the direction
of lesser radii. Unlike the modern lion’s the found fur has very
thick and dense woolly undercoat of numerous closely shut
and compressed wavy woolly hairs with the medulla. The
coloration of the hair is not fully similar to that of the modern
lion. The microstructure and degree of development of the
medulla and the cortex, and the ornament of the cuticle
look similar between modern species and the found sample,
but the cuticular scales of the 6nd are larger. Because of the
small size of the tuft and absence of other cave lion hair
samples for comparison it is not possible to determine its
origin topographically or relate to a season. Its attribution to
a lion is still debatable.
Radiocarbon AMS dating was performed at ANSTO (Fink et
al., 2004) for samples taken from a rib, claw sheath and fur
tuft (lab codes OZQ290, OZQ291, OZQ292). Bone sample
exhibited good collagen preservation, consistent with
its origin from permafrost. Keratin was analysed for claw
and fur. Both rib and claw gave 14C dates greater than 61
thousand years. Fur in contrast came out much younger
(28690+130 14C years), which makes it impossible to come
from the same specimen as the bones. However, its stable
isotope signature 6ts that for the carnivore.
The remains from the Maly Anuy River represent the 6rst
associated skeleton of cave lion found in Russia and the
most ancient for the region
The potential of ITRAX core scanning: applications in Quaternary Science
No full textThe ITRAX is a multi-function core scanner and is being increasingly used in the fields of Quaternary geology, environmental science and climate science. The scanner is equipped with micro-XRF (X-Ray Fluorescence) instrumentation, which is capable of measuring a wide range of elements at very small scanning intervals. In addition to this, the instrument can also take high resolution optical and Xradiograph
images and measure magnetic susceptibility. An ITRAX has been located in the
laboratories of the Australian Nuclear Science and Technology Organisation (ANSTO) since 2012, and was funded by an ARC-LIEF grant. ANSTO was able to provide a purpose build room and ancillary facilities, such as Geotek core-splitter, dendrocut saw and sample storage, as part of the upgrade of the Environmental Radioactivity Measurement Centre. The ITRAX is capable of scanning
resolutions of 200μm for XRF measurements and optical images, and 60μm for X-radiograph images.
The ITRAX at ANSTO is unique in its capability to measure sediments, carbonate systems and tree
ring samples. An overview of the applications of the ITRAX-scanning in various fields is presented in
this poster