5 research outputs found
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Separation of minor actinides from lanthanides using immobilized ligand systems: the role of the counterion
A CyMe4-BTPhen functionalized silica gel that selectively extracts Am(III) over Eu(III) from 4 M HNO3 with a separation factor > 154 has been developed. Evidence is presented that the counterion surrounding the M(III) in the proposed 1:1 [BTPhen:M(III)] complex plays an important role in the complexation of Am(III) and Eu(III)
Genomic and Epigenetic Changes Drive Aberrant Skeletal Muscle Differentiation in Rhabdomyosarcoma
Rhabdomyosarcoma (RMS), the most common soft-tissue sarcoma in children and adolescents, represents an aberrant form of skeletal muscle differentiation. Both skeletal muscle development, as well as regeneration of adult skeletal muscle are governed by members of the myogenic family of regulatory transcription factors (MRFs), which are deployed in a highly controlled, multi-step, bidirectional process. Many aspects of this complex process are deregulated in RMS and contribute to tumorigenesis. Interconnected loops of super-enhancers, called core regulatory circuitries (CRCs), define aberrant muscle differentiation in RMS cells. The transcriptional regulation of MRF expression/activity takes a central role in the CRCs active in skeletal muscle and RMS. In PAX3::FOXO1 fusion-positive (PF+) RMS, CRCs maintain expression of the disease-driving fusion oncogene. Recent single-cell studies have revealed hierarchically organized subsets of cells within the RMS cell pool, which recapitulate developmental myogenesis and appear to drive malignancy. There is a large interest in exploiting the causes of aberrant muscle development in RMS to allow for terminal differentiation as a therapeutic strategy, for example, by interrupting MEK/ERK signaling or by interfering with the epigenetic machinery controlling CRCs. In this review, we provide an overview of the genetic and epigenetic framework of abnormal muscle differentiation in RMS, as it provides insights into fundamental mechanisms of RMS malignancy, its remarkable phenotypic diversity and, ultimately, opportunities for therapeutic intervention
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Extraction properties of 4-Tetra(hydroxyphenyl)BTPhen in liquid-liquid extraction systems with Cyclohexanone/Octanol or in a solid-phase extraction system
The extraction properties of tetra(4-hydroxyphenyl)BTPhen have been investigated. Liquid-liquid extraction studies in proposed SANEX diluents, cyclohexanone and 1-octanol, indicate that actinide-lanthanide separation is superior in cyclohexanone; whereas actinide-actinide separation is more efficient in 1-octanol. Immobilization of the ligand onto a silica support results in the separation factor becoming dependent upon the concentration of nitrate anions in the aqueous phase. The immobilized ligand was also applied to the extraction of transition metals, resulting in >70% uptake of all transition metals examined, in the presence of alkali and alkaline earth metals
How can we achieve a sustainable nuclear fuel cycle?
Dealing with spent nuclear fuel is key if nuclear fission is to be used more widely going forward. Nuclear power is close to carbon neutral, but spent nuclear fuel has a storage lifetime of ~300,000 years. Reprocessing spent nuclear fuel is carried out on large scale using the PUREX âPlutonium Uranium Reduction and Extractionâ process. The spent nuclear fuel is reduced to 15% of its original weight and the separated uranium and plutonium reused as âMixed Oxide Fuelâ. In the civil sector, this was carried out by the UK at Sellafield (now curtailed) and continues in France at La Hague. A plant in Rokashamura in Japan has been mothballed after the Fukushima accident. The residual waste must be stored for ~9,000 years with most of the remaining radiotoxicity due to traces of the minor actinides, neptunium, americium and curium, constituting just 0.1% of the original spent fuel. Separation of these minor actinides from the chemically very similar lanthanides (rare earths) in the last 15% of waste remaining after PUREX is the key step for future reprocessing. If separated, the minor actinides can be used as fuel in the next generation of nuclear reactors and converted into benign products, but lanthanides will cause the fission process to shut down if introduced into the reactor pile as they absorb neutrons efficiently. Removing the minor actinides from post PUREX waste will mean that the final residue need only be stored for 300 years. The highly challenging separation of the chemically very similar minor actinides from the lanthanides has been achieved using nitrogen-bearing organic ligands developed at Reading University. This can lead to significantly improved handling of spent nuclear fuels and means that waste nuclear fuel need not be a long-term storage liability but a source of yet more clean power
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Synthesis of novel metal selective ligand systems
The Rare Earth Elements (REEs) are becoming increasingly vital in todayâs modern society,
with uses in mobile phones, televisions, wind turbines, light bulbs and medical equipment.
Despite the fact they are used so regularly, only 1% of all REEs are recycled from end-of-life
products. REEs are currently some of the most critical elements on the critical elements list
and with their demand so high, strategies must be put in place to keep up with this increasing
demand.
Chapter 1 This work summarizes the occurrence of these elements in the Earthâs crust and
their uses and demands in modern life. The mining and processing of REEs involves multiple
stages including leaching, benefaction, pyrometallurgy and hydrometallurgy; either ion
exchange or solvent exchange to afford pure REEs. The reprocessing of REEs from end-of-life products is also discussed.
Chapter 2 Neocuproine immobilized silica gel (NC-Si) contains an N-donor phenanthroline
substituent able to bind to REEs and provide a way to separate REEs from each other
providing a potential method for the reprocessing of REEs. This study explores the adsorption
and desorption of REEs from a fixed-bed column of NC-Si. Thermogravimetric analysis (TGA)
confirmed that approximately 5% w/w of neocuproine content was present on the NC-Si,
resulting in a molarity of 0.1466 mmol per gram of adsorbent. The adsorption capacities of NCSi for all REEs (including Sc and Y) ranged from 0.0005 to 0.0012 mg g-1, with a preference
for the late REEs (Ho-Lu), with an overall adsorption capacity of 0.0153 mg g-1. Breakthrough
times (tb) were used to classify the REEs series into three groups; early (Y, La-Pr) (<3 mins),
mid (Sc, Nd-Dy) (3.5 - 15 mins), and late (Ho-Lu) (>44 mins), indicating the potential of NC-Si
for REE separations. Different models; Adams-Bohart, Thomas, Yoon Nelson, Modified Dose
Response (MDR), and Lagergren's pseudo first and second order rate kinetics were applied
to describe the adsorption of the multicomponent solution. The Yoon-Nelson model had the
highest correlation coefficient (R2
â 0.95) and effectively fit the mid and later REEs (Nd-Lu)
among all the models tested. The MDR and Thomas models showed good fitting for early (R2
â 0.95) and early/mid (R2
â 0.93) REEs, respectively. The Adams-Bohart model provided the
lowest correlation coefficient (R2
â 0.81) but was able to describe all ions.
Chapter 3 Similarly to NC-Si, CyMe4-BTPhen also contains a phenanthroline functional group
and is able to bind to REEs, however separation of REE is not as efficient. CyMe4-BTPhen
was immobilised onto silica (BTPhen-Si) and fixed-bed column techniques were carried out.
BTPhen-Si had an overall adsorption capacity of 0.048 mg g-1 with adsorption capacities
ranging from 0.0016 to 0.0038 mg g-1 for Y and Sc, respectively. Based on the breakthrough
times (tb) the series could be separated into two groups, mid REE ions (Pr-Eu) (>3 mins) and
late REE ions (Gd-Lu) (<1.5 mins), however Sc and Ce would elute with the mid REE ions,
whereas Y and La elute with the late REEs. Adams-Bohart and Thomas models were able to describe all ions (Sc, Y and all REEs), however they gave the lowest correlation coefficients
at R2
= ~0.86 and 0.9, respectively. Yoon-Nelson and MDR were not able to describe Sc, Pr,
Nd, Sm and Eu. BTPhen-Si shows potential as a material for extracting REE ions, but further
improvements are needed to enhance separation and adsorption capacities.
Chapter 4 Four ligand systems were developed to investigate extraction and partition
capabilities of REEs in a fixed-bed column system which allowed comparison with NC-Si and
BTPhen-Si. All ligands contained the phenanthroline functional group but all had different
linkages to the silica gel. ANC-Si, BNC-Si, HANC-Si and TBTPhen-Si were successfully
synthesized, characterised and measured for REE extraction. The models; Adams-Bohart,
Thomas, Yoon Nelson and Modified Dose Response (MDR) were applied to the breakthrough
curves of each of the ligand systems. HANC-Si could not be described by any model, however
BNC-Si and TBTPhen-Si were best described by MDR and ANC-Si described by AdamsBohart and Thomas. Adsorption capacities of the four ligand systems were as followed for
ANC-Si, BNC-Si, HANC-Si and TBTPhen-Si; 0.0106, 0.0157, 0.0101 and 0.00484 mg g-1.
Cost, REE separation, w/w% and adsorption capacities were compared to for all four ligands
as well as with NC-Si and BTPhen-Si. Overall, NC-Si was the most efficient at separating the
REEs from each other into small sub-groups of REEs. BTPhen-Si had the highest adsorption
capacity out of the six ligands (0.0484 mg g-1)