313 results on '"Williams CK"'
Search Results
2. Indium phosphasalen catalysts showing high isoselectivity and activity in racemic lactide and lactone ring opening polymerizations
- Author
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Williams, CK, Yuntawattana, N, McGuire, TM, Durr, CB, and Buchard, A
- Subjects
chemistry.chemical_classification ,Lactide ,010405 organic chemistry ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Copolyester ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Polymerization ,Polymer chemistry ,Phenyl group ,Stereoselectivity ,Indium ,Lactone - Abstract
Stereoblock polylactide (PLA) shows higher melting temperatures and better mechanical properties than other PLA stereoisomers. More stereoselective and active catalysts are needed to polymerize racemic-lactide (LA) and produce stereoblock PLA. This work describes a series of phosphasalen indium catalysts (1–5) which result in very high isoselectivity, at room temperature, (Pi = 0.91, 25 °C) and high activity, at low catalyst loading (TOF = 100 h−1, 1 : 500 catalyst : LA, [LA] = 1 M, THF, 25 °C). The catalyst structure–activity and structure–stereoselectivity relationships are investigated using various experimental methods and DFT calculations. The most isoselective catalyst features two different phosphasalen substituents, a tert-butyl and phenyl group, it forms an achiral, meso indium complex which operates by a chain end control mechanism. The work highlights the benefits of phosphasalen ligands and identifies new avenues for catalyst investigation by exploitation of asymmetrically substituted phosphorus atoms. The catalysts also show good activity and control for the ring-opening polymerizations of ε-caprolactone, β-butyrolactone, ε-decalactone and δ-hexalactone (γ-methyl-δ-valerolactone), demonstrating future potential for copolyester production.
- Published
- 2020
3. Bio‐based and degradable block polyester pressure‐sensitive adhesives
- Author
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Chen, TTD, Carrodeguas, LP, Sulley, GS, Gregory, GL, and Williams, CK
- Subjects
Materials science ,Polymers ,ring-opening polymerization ,block polyesters ,Polyesters ,Tackifier ,010402 general chemistry ,01 natural sciences ,Ring-opening polymerization ,Catalysis ,Polymerization ,chemistry.chemical_compound ,Adhesives ,Block (telecommunications) ,chemistry.chemical_classification ,Polymer science ,010405 organic chemistry ,Communication ,General Chemistry ,Polymer ,General Medicine ,degradable polymers ,Communications ,0104 chemical sciences ,Polyester ,Monomer ,chemistry ,Pressure sensitive ,Adhesive - Abstract
A new class of bio‐based fully degradable block polyesters are pressure‐sensitive adhesives. Bio‐derived monomers are efficiently polymerized to make block polyesters with controlled compositions. They show moderate to high peel adhesions (4–13 N cm−1) and controllable storage and loss moduli, and they are removed by adhesive failure. Their properties compare favorably with commercial adhesives or bio‐based polyester formulations but without the need for tackifier or additives., Well‐defined bio‐based triblock polyesters were prepared using a mixture of renewable monomers and a one‐pot synthetic method with a single catalyst. These materials are pressure‐sensitive adhesives and are easily degraded under acidic conditions.
- Published
- 2020
4. Colloidal Cu/ZnO catalysts for the hydrogenation of carbon dioxide to methanol: investigating catalyst preparation and ligand effects
- Author
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Pike, SD, García-Trenco, A, White, ER, Leung, A, Weiner, J, Shaffer, MSP, Williams, CK, and Engineering & Physical Science Research Council (EPSRC)
- Subjects
CO2 HYDROGENATION ,Science & Technology ,Chemistry, Physical ,LIQUID-PHASE METHANOL ,NANOCRYSTAL SURFACES ,PALLADIUM NANOPARTICLES ,PARTICLE-SIZE ,METAL-SUPPORT INTERACTIONS ,Chemistry ,GAS ,Physical Sciences ,ZNO ,ACTIVE-SITES ,CU - Abstract
The production of methanol from CO 2 hydrogenation is a promising potential route to a renewable liquid fuel and renewable energy vector. Herein, three distinct routes to make colloidal catalysts based on mixtures of Cu(0) and ZnO nanoparticles (NPs) and using low-temperature organometallic procedures are reported. The colloids are surface coordinated by a phosphinate ligand: dioctylphosphinate ([DOPA] - ), which delivers a high solubility in organic solvents. Further, the synthetic routes allow fine control of the ZnO:Cu and ligand loadings. The catalysts are prepared by mixing s mall NPs (2 nm) of either Cu(0) or air-stable Cu 2 O NPs with ZnO NPs (3 nm), or by the synthesis of Cu(0) in presence of ZnO NPs (ZnO: 2 nm, Cu: 6 nm). The resulting colloidal catalysts are applied in the liquid phase hydrogenation of CO 2 to methanol (210 °C, 50 bar, 3:1 molar ratio of CO 2 :H 2 ). The catalysts typically exhibit 3 times higher rates when compared to a heterogeneous Cu-ZnO-Al 2 O 3 commercial catalyst (21 vs. 7 mmol MeOH g CuZnO -1 h -1 ). The characterisation of the post-catalysis colloids show clear Cu/ZnO interfaces (HR-TEM), which are formed under reducing conditions, as well as differences in the Cu(0) NP size (from 3 to 7 nm) and nanoscale restructuring of the catalysts. The combination of characterisation and catalytic results indicate that the activity is mostly dictated by the Cu(0) particle size and ligand loading. Smaller Cu(0) NPs exhibited lower turnover frequency (TOF) values, whereas higher ligand loadings ([DOPA] - :(Cu + Zn) of 0.2-1.1) lead to smaller Cu(0) NPs and reduce the formation of Cu/ZnO interfaces. UV-vis spectroscopy reveals that the Cu(0) NPs are more stable to oxidation under air after catalysis than beforehand, potentially due to migration of ZnO onto the Cu surface whilst under catalytic conditions.
- Published
- 2017
5. Ring opening polymerization of macrolactones: High conversions and activities using an yttrium catalyst
- Author
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Myers, D, Cyriac, A, Bown, M, Witt, T, Mecking, S, and Williams, CK
- Subjects
ddc:540 - Abstract
The ring-opening polymerization of macrolactones (C15-C23) enables the production of long-chain aliphatic polyesters which are crystalline polymers with melting temperatures ranging from 80 – 110 °C. Here, the polymerization of ω-pentadecalactone (C15), nonadecalactone (C19) and tricosalactone (C23) are investigated using an yttrium phosphasalen catalyst. The catalyst enables typical conversions to exceed >80% and the reactions occur either in neat monomer or in solution in toluene, over the temperature range 25- 100 °C. The yttrium catalyst shows higher activities than previously reported aluminium-salen complexes, with TOF values in the range 200-400 h-1 in the best cases. The polymerizations occur with linear increase in molecular weight vs. conversion and enable the production of polyester with 10 < Mn < 60 kg mol-1. Using tricosalactone the polymerization thermodynamic parameters are determined and confirm the polymerization is entropically driven. The findings underscore the importance of continued catalyst development to allow higher rates of reaction which has the added benefit of accessing the highest conversions to polymer.
- Published
- 2017
6. Metal-Size Influence in Iso-Selective Lactide Polymerization
- Author
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Bakewell, C, White, AJP, Long, NJ, Williams, CK, and Engineering & Physical Science Research Council (EPSRC)
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Science & Technology ,lanthanum ,ring-opening polymerization ,Chemistry, Multidisciplinary ,Organic Chemistry ,STEREOCOMPLEX FORMATION ,General Medicine ,iso-selectivity ,RACEMIC LACTIDE ,STEREOSELECTIVE POLYMERIZATION ,3. Good health ,lutetium ,Chemistry ,YTTRIUM PHOSPHASALEN INITIATORS ,BIS(PHENOLATO) LIGANDS ,RAC-LACTIDE ,Physical Sciences ,lactide ,CYCLIC ESTERS ,03 Chemical Sciences ,ALUMINUM COMPLEXES ,INDIUM CATALYST - Abstract
Iso-selective initiators for the ring-opening polymerization (ROP) of rac-lactide are rare outside of Group 13. We describe the first examples of highly iso-selective lutetium initiators. The phosphasalen lutetium ethoxide complex shows excellent iso-selectivity, with a Pi value of 0.81–0.84 at 298 K, excellent rates, and high degrees of polymerization control. Conversely, the corresponding La derivative exhibits moderate heteroselectivity (Ps=0.74, 298 K). Thus, the choice of metal center is shown to be crucial in determining the level and mode of stereocontrol. The relative order of rates for the series of complexes is inversely related to metallic covalent radius: that is, La>Y>Lu.
- Published
- 2014
7. Mononuclear Phenolate Diamine Zinc Hydride Complexes and Their Reactions With CO2
- Author
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Brown, NJ, Harris, JE, Yin, X, Silverwood, I, White, AJP, Kazarian, SG, Hellgardt, K, Shaffer, MSP, and Williams, CK
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Article - Abstract
The synthesis, characterization, and zinc coordination chemistry of the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2′-dimethylaminoethyl)methylamino]methyl}phenol are described. Each of the ligands was reacted with diethylzinc to yield zinc ethyl complexes 4–6; these complexes were subsequently reacted with phenylsilanol to yield zinc siloxide complexes 7–9. Finally, the zinc siloxide complexes were reacted with phenylsilane to produce the three new zinc hydride complexes 10–12. The new complexes 4–12 have been fully characterized by NMR spectroscopy, mass spectrometry, and elemental analyses. The structures of the zinc hydride complexes have been probed using VT-NMR spectroscopy and X-ray diffraction experiments. These data indicate that the complexes exhibit mononuclear structures at 298 K, both in the solid state and in solution (d8-toluene). At 203 K, the NMR signals broaden, consistent with an equilibrium between the mononuclear and dinuclear bis(μ-hydrido) complexes. All three zinc hydride complexes react rapidly and quantitatively with carbon dioxide, at 298 K and 1 bar of pressure over 20 min, to form the new zinc formate complexes 13–15. The zinc formate complexes have been analyzed by NMR spectroscopy and VT-NMR studies, which reveal a temperature-dependent monomer–dimer equilibrium that is dominated by the mononuclear species at 298 K.
- Published
- 2014
8. Simple Phosphinate Ligands Access New Zinc Clusters Identified in the Synthesis of Zinc Oxide Nanoparticles
- Author
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Pike, S, White, E, Shaffer, M, Williams, CK, and Engineering & Physical Science Research Council (EPSRC)
- Subjects
MD Multidisciplinary - Abstract
The bottom-up synthesis of ligand-stabilised functional nanoparticles from molecular precursors is widely applied but difficult to study mechanistically. Here, we use 31P NMR spectroscopy to follow the trajectory of phosphinate ligands during the synthesis of a range of new ligated zinc oxo clusters, containing 4, 6 and 11 zinc atoms. Using an organometallic route, the clusters interconvert rapidly, and self-assemble in solution based on thermodynamic equilibria, rather than nucleation kinetics. These clusters are also identified, in situ, during the synthesis of phosphinate-capped zinc oxide nanoparticles. Unexpectedly, the ligand is sequestered to a stable Zn11 cluster during the majority of the synthesis and only becomes coordinated to the nanoparticle surface, in the final step. As well as a versatile and accessible route to new (optionally doped) zinc clusters, the findings provide a new understanding of the role of well-defined molecular precursors during the synthesis of small (2-4 nm) nanoparticles.
- Published
- 2016
9. Polymer synthesis: To react the impossible ring
- Author
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Myers, D, Cyriac, A, Williams, CK, and Commission of the European Communities
- Subjects
Organic Chemistry ,03 Chemical Sciences - Published
- 2015
10. Sequence selective polymerization catalysis: A new route to ABA block copoly(ester-b-carbonate-b-ester)
- Author
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Williams, CK, Paul, S, Romain, C, and Shaw, J
- Published
- 2015
11. Dinuclear metal catalysts: improved performance of heterodinuclear mixed catalysts for CO2-epoxide copolymerization
- Author
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Saini, PK, Romain, C, Williams, CK, and Engineering & Physical Science Research Council (EPSRC)
- Subjects
Science & Technology ,Chemistry, Multidisciplinary ,Organic Chemistry ,PROPYLENE-OXIDE ,CYCLOHEXENE OXIDE ,STEREOCHEMISTRY CONTROL ,CO2/PROPYLENE OXIDE COPOLYMERIZATION ,DIIMINATE ZINC CATALYSTS ,CO2/EPOXIDE COPOLYMERIZATION ,Chemistry ,CARBON-DIOXIDE ,EPOXIDE/CO2 COPOLYMERIZATION ,Physical Sciences ,POLYCARBONATE SYNTHESIS ,ALTERNATING COPOLYMERIZATION ,03 Chemical Sciences - Abstract
Some of the most active catalysts for carbon dioxide and epoxide copolymerization are dinuclear metal complexes. Whilst efficient homodinuclear catalysts are known, until now heterodinuclear catalysts remain unreported. Here, a facile, in situ route to a catalyst system comprising a mixture of homo- and heteronuclear Zn–Mg complexes is presented. This catalyst system shows excellent polymerization control and exhibits significantly higher activity than the homodinuclear catalysts alone or in combination.
- Published
- 2014
12. An overview of CO2 capture technologies
- Author
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MacDowell, N, Florin, N, Buchard, A, Hallett, J, Galindo, A, Jackson, G, Adjiman, CS, Williams, CK, Shah, N, and Fennell, P
- Subjects
Energy - Abstract
In this paper, three of the leading options for large scale CO2 capture are reviewed from a technical perspective. We consider solvent-based chemisorption techniques, carbonate looping technology, and the so-called oxyfuel process. For each technology option, we give an overview of the technology, listing advantages and disadvantages. Subsequently, a discussion of the level of technological maturity is presented, and we conclude by identifying current gaps in knowledge and suggest areas with significant scope for future work. We then discuss the suitability of using ionic liquids as novel, environmentally benign solvents with which to capture CO2. In addition, we consider alternatives to simply sequestering CO2 - we present a discussion on the possibility of recycling captured CO2 and exploiting it as a C1 building block for the sustainable manufacture of polymers, fine chemicals, and liquid fuels. Finally, we present a discussion of relevant systems engineering methodologies in carbon capture system design. © 2010 The Royal Society of Chemistry.
- Published
- 2010
13. Effectiveness and Cost-Efficiency of Control of the Wild Rabbit, Oryctolagus Cuniculus (L.), By Combinations of Poisoning, Ripping, Fumigation and Maintenance Fumigation.
- Author
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Williams, CK, primary and Moore, RJ, additional
- Published
- 1995
- Full Text
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14. Inheritance of Acquired-Immunity to Myxomatosis
- Author
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Williams, CK, primary and Moore, RJ, additional
- Published
- 1991
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15. Application of the IV Medication Harm Index to assess the nature of harm averted by 'smart' infusion safety systems.
- Author
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Williams CK, Maddox RR, Heape E, Richards HE, Griffiths DL, and Crass RE
- Published
- 2006
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16. Implementation of an I.V. medication safety system.
- Author
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Williams CK and Maddox RR
- Published
- 2005
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17. Genetic-Resistance to Myxomatosis in Australian Wild Rabbits, Oryctolagus-Cuniculus (L)
- Author
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Williams, CK, primary, Moore, RJ, additional, and Robbins, SJ, additional
- Published
- 1990
- Full Text
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18. The PNH abnormality in myeloproliferative disorders: association of PNH and acute erythremic myelosis in two children
- Author
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LUZZATTO L, FAMILUSI JB, WILLIAMS CK, JUNAID TA, ROTOLI B, ALFINITO, FIORELLA, Luzzatto, L, Familusi, Jb, Williams, Ck, Junaid, Ta, Rotoli, B, and Alfinito, Fiorella
- Published
- 1979
19. Rates of Herbage Ingestion and Turnover of Water and Sodium in Feral Swamp Buffalo, Bubalus Bubalis, in Relation to Primary Production in a Cyperaceous Swamp in Monsoonal Northern Australia.
- Author
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Williams, CK and Ridpath, MG
- Abstract
During a monsoonal dry season, a free-living population of swamp buffalo inhabiting an ephemeral cyperaceous swamp on the floodplain of the South Alligator River had high rates of water turnover. The daily rate of consumption of Eleocharis sphacelata was c. 5.79 kg DM/animal or 49.2 plus or minus 2.77 g/l total body water-0.82. Annual herbage production in the 13.1 ha swamp was estimated at 80.43 t. Buffalo using the swamp varied from 42 in the mid-wet season and 20 in the late-wet season to c. 200 in the dry season. Herbaceous vegetation was grazed out by the end of the arid phase of the monsoonal cycle. The dependence of buffalo on water which confines them during the arid season and results in intense grazing and changes in floristic composition is discussed.
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- 1982
- Full Text
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20. Environmental and Genetic Influences on Growth of the Wild Rabbit, Oryctolagus-Cuniculus (L) in Australia
- Author
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Williams, CK and Moore, RJ
- Abstract
Environmental variation caused more variation in the growth rates of wild rabbits than did genetic divergence among populations in three climatic regions in Australia. The growth of various parts of the body responded to different environmental influences. Growth of the body core of kittens varied with the number of littermates. Growth of the pes varied with ambient temperature and the number of littermates. Growth of the pinnae, organs with special thermoregulatory function, was affected markedly by ambient temperature. Growth rates in regional rabbit populations differed consistently in two generations, manifesting differences in physiology and possible genetic divergence. Sub-alpine rabbits grew faster in body length and head length than did rabbits of mediterranean and arid climates. The extremities of mediterranean rabbits grew slower than those of arid and sub-alpine rabbits. The regional variation in growth physiology was determined either by persisting influence of the field environments transmitted maternally through two generations, or by genetic divergence of populations since the few progenitors were introduced to Australia 125 years previously.
- Published
- 1989
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21. Ecology of Australian Chats (Epthianura Gould): Aridity, Electrolytes and Water Economy.
- Author
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Williams, CK and Main, AR
- Abstract
The four species of Australian chats differentially occupy semiarid and arid regions where surface water commonly contains high concentrations of electrolytes, especially during the summer. The effects of variations in ambient temperature and salinity of drinking water on nutrition, water and electrolyte balances were compared between three species of chats in a split-plot, factorial design. The homeostatic responses revealed very complex interactions between thermoregulation, nutrition, and balances of electrolytes and water. All species have very low tolerance of electrolytes in the drinking water. Ingested electrolytes are not stored but are rapidly excreted in low concentrations at the expense of body water. Survival of chats in arid regions depends on a high degree of selectivity in avoiding water sources with even moderate concentrations of electrolytes. This avoidance is achieved by nomadism and seasonal movements to areas of recent rainfall, thereby increasing the access to water with low concentrations of electrolytes. The ability of the more xeric species to occupy regions of greater aridity cannot be explained by enhanced abilities to excrete electrolytes in high concentrations. The three species studied excrete electrolytes in similar, low concentrations. The more xeric species possess an advantage in water and electrolyte balances through lower evaporative losses of body water, especially at high ambient temperatures.
- Published
- 1977
- Full Text
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22. Ecology of Australian chats (Epthianura Gould) season movements, metabolism and ecaporative water loss
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Williams, CK and Main, AR
- Abstract
The four species of Australian chats differ in their utilization of arid regions. Comparisons were made between the rates of metabolism and evaporative water loss of three species at moderate and high ambient temperatures, after trapping in the field during winter and after acclimation in the laboratory to 22C and 14C. When acclimated to winter temperatures the three species had similar rates of metabolism at moderate and high ambient temperatures. The rates of evaporative water loss at moderate temperatures were similar, but at temperatures above the thermoneutral zone the rates were lower in the more xeric than the more mesic species. When acclimated to summer temperatures the more xeric species had lower rates of metabolism and evaporative water loss than the more mesic species at temperatures within and above the thermoneutral zone. Variation in the rates of metabolism and evaporative water loss in field populations was greatest in the most mesic species and least in the most xeric species. Rates of metabolism and evaporative water loss were lower in all species after acclimation to 22C than after acclimation to 14C. The rates of metabolism and evaporative water loss tended to be lower than the rates predicted on the basis of body weight. In thermoregulation at high ambient temperatures the more xeric species evaporated relatively less body water in dissipating body heat than the more mesic species, apparently without a greater increase in body temperature. The ability of Australian chats to utilize semiarid and arid regions is explained by distributions and seasonal movements which complement the physiology of evaporative water loss and thermoregulation in a manner that enhances survival at high ambient temperatures.
- Published
- 1976
- Full Text
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23. Water Physiology and Nutrition in Fluctuating Populations of Rattus-Colletti in Monsoonal Northern-Territory, Australia
- Author
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Williams, CK
- Abstract
During wet and dry seasons and transitions of the monsoonal cycle, rates of water turnover and nutritional variables were measured on a population of Rattus colletti which fluctuated between extremes of high and low abundance. Rate of water turnover (RWT in millilitres per day) and body weight ( W, in kilograms) were related allometrically: RWT = aW*O.742 0.061, where a varied between seasons and sexes. Seasonal rates of water turnover were consistent with physiological adaptation in R. colletti to seasonal aridity. Rate of water turnover correlated with seasonal hydric regime, varying by a factor of 3.5 between dry and wet seasons. During the wet season, low body weight and lack of breeding seemed to be caused by flooding and its physical and social consequences. During dry season aridity the rats were short of food and water, but not in a dry season when rain fell and breeding ensued. Reproduction increased requirements for food and water in both sexes. Juveniles had relatively high requirements, and shortages appeared to retard growth. Very large populations resulted from prolific breeding after dry season rain had sustained high consumption of food and water on the riverine plains, the dry season habitat. Population decline resulted from very high wet season rainfall followed by a rainless dry season when food and water intakes were depressed, probably because the previous rainfall pattern reduced the availability of sedge corms, the dry season source of food and water. This climatic pattern recurred in the next wet and dry seasons, reinforcing the effects on R, colletti, which became rare for several years on both riverine systems studied.
- Published
- 1987
- Full Text
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24. Variations in Seasonal Nutrition, Thermoregulation and Water Balance in Two New Zealand Populations of the Common Brushtail Possum, Trichosurus Vulpecula (Phalangeridae).
- Author
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Williams, CK and Turnbull, HL
- Abstract
Two populations of common brushtail possum, at Wanganui in the North Island of New Zealand and Westland in the South Island, were compared in aspects of nutrition, thermoregulation and water balance at 2 thermal conditions in controlled-environment rooms. The thermal conditions and adaptation had no influence on nutrition and water balance but caused variation in bodyweight and in rates of food intake and water turnover, both relative to metabolic body size. Although the 2 populations differed greatly in body mass they had different rates of food intake relative to metabolic size, but similar individual rates. Rates of metabolized energy intake followed a similar pattern. Conversely, rates of water turnover relative to metabolic size were similar between populations but differed for individuals. The trend for differences between populations in indices of urine concentration were associated with different patterns of food and water intakes. These differences cannot be explained in terms of body mass increments. The physiological variation between populations was greatly influenced by differences in body size, which accord with Bergmann's rule. The larger size of the Westland animals is advantageous during abstinence from feeding during frequent foul weather, and the smaller size of the Wanganui animals confers advantages in water balance during annual periods of prolonged rainfall deficiency.
- Published
- 1983
- Full Text
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25. Ingestion Rates and Aspects of Water, Sodium and Energy Metabolism in Caged Swamp Buffalo, Bubalus Bubalis, From Isotope Dilution and Materials Balances.
- Author
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Williams, CK and Green, B
- Abstract
Exchanges of DM, sodium, water and energy were estimated on caged swamp buffalo of body mass (W) 297 plus or minus 13 kg. Estimates of feed ingestion estimated from rates of 22Na and 3H turnover were in close agreement with estimates from weighing. Tritium equilibrated in 6 h and 22Na in 12 h. Tritium space was 78.9 plus or minus 1.6% of body mass at 6 h and 83.9 plus or minus 1.1% at 24 h. The body pool of exchangable Na was 40.56 plus or minus 1.79 mmol/kg W at 12 h, and 44.62 plus or minus 2.12 mmol/kg W at 24 h. The daily rate of water turnover was 34.72 plus or minus 2.33 litres or 326.1 plus or minus 17.2 ml/kg W0.82, about three times that expected on the basis of body size, reflecting adaptation to a tropical swamp habitat. It was due mainly to the high rate of imbibition, 30.78 plus or minus 2.15 litres daily or 289.1 plus or minus 16.3 ml/kg W0.82 daily. Daily rates of water loss were partitioned as: faecal, 9.99 plus or minus 0.761 (94.1 plus or minus 7.0 ml/kg W0.82); urinary, 10.39 plus or minus 0.76 litres (98.2 plus or minus 7.6 ml/kg W0.82); pulmocutaneous, 14.34 plus or minus 1.37 litres (133.8 plus or minus 8.9 ml/kg W0.82). Swamp buffalo are unlikely to be able to satisfy their water requirements from food alone during the dry season in northern Australia. The daily rate of Na turnover was 6.29 plus or minus 0.41 mmol/kg W0.75. Na in the faeces was low, 8.3 plus or minus 0.9 mmol/kg dry faeces, indicating very effective alimentary absorption of Na. Apparent digestible energy intake (DE) per day for maintenance was about 651 plus or minus 41 kJ/kg W0.75. Daily rates of evaporative heat loss were high, 481 plus or minus 33 kJ/kg W0.75, exceeding the non-evaporative component of the DE, 321 plus or minus 35 kJ/kg W0.75; evaporative processes may have contributed to the high maintenance DE.
- Published
- 1982
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26. Ecology of Australian Chats (Epthianura Gould): Reproduction in Aridity.
- Author
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Williams, CK
- Abstract
The four species of Australian chats differentially occupy arid regions and are considered to have problems of water balance during reproduction. They breed mainly during the winter semester, when ambient temperatures and vapour pressure deficit are lower and evaporative losses of body water are reduced. During a drought breeding is depressed; but chats breed opportunistically after abundant rainfall and exploit, by nomadism, the unpredictable rainfall in semiarid and arid Australia. The breeding season of the most mesic species, Epthianura albifrons, is reduced in the more xeric regions. In arid sympatric breeding areas the more xeric species have the more extended breeding seasons. Chats are territorial only during reproduction. The male protects the receptive female and the eggs and offspring, but not environmental resources. Territorial defence involves plumage pigmentation consistent with Gloger's rule, plumage patterns, postures and ritualized fighting displays. Territoriality and territorial behaviour are reduced in the more mesic species. This is consistent with relative rates of evaporative water loss, synchrony and apparent density of nesting, water requirements and physiological adaptation to aridity. A hypothesis is presented which suggests an adaptive hormonal mechanism relating to physiological adaptation to aridity and determining the different plumages.
- Published
- 1979
- Full Text
- View/download PDF
27. Inhibitory effects of human leukocyte and fibroblast interferons on normal and chronic myelogenous leukemic granulocytic progenitor cells
- Author
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Takao Ohnuma, Svet-Moldavskaya I, Williams Ck, Jan Vilcek, and James F. Holland
- Subjects
Cancer Research ,Biology ,In Vitro Techniques ,Myelogenous ,Interferon ,medicine ,Leukocytes ,Humans ,Progenitor cell ,Fibroblast ,Cells, Cultured ,Antiserum ,Immunogenicity ,Immune Sera ,Cancer ,General Medicine ,Fibroblasts ,medicine.disease ,Hematopoietic Stem Cells ,medicine.anatomical_structure ,Oncology ,Leukemia, Myeloid ,Immunology ,Interferons ,medicine.drug ,Chronic myelogenous leukemia - Abstract
Inhibitory effects of two human interferon preparations, leukocyte interferon (Le-IF) and fibroblast interferon (F-IF), on granulocytic progenitor cells (CFU-C) from hematologically normal cancer patients and from patients with chronic myelogenous leukemia were evaluated. There was a wide variation in sensitivity of CFU-C to both Le-IF and F-IF. F-IF was more inhibitory against CFU-C than Le-IF. Normal CFU-C and chronic myelogenous Leukemia CFU-C were equally inhibited by both interferons. Effects of both interferons were neutralized by corresponding specific antisera but not by the other antisera. These observations confirmed that differences in immunogenicity of the interferons may attend their different origins.
- Published
- 1981
28. Ingestion rates, food utilization and turnover of water and sodium in grazing buffaloes, Bubalus bubalis, and cattle, Bos taurus × B. indicus, in monsoonal Northern Territory
- Author
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Williams, CK, primary and Dudzinski, ML, additional
- Published
- 1982
- Full Text
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29. A sensitive assay of 5-fluorouracil in plasma by gas chromatography- mass spectrometry.
- Author
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Hillcoat, BL, primary, Kawai, M, additional, McCulloch, PB, additional, Rosenfeld, J, additional, and Williams, CK, additional
- Published
- 1976
- Full Text
- View/download PDF
30. X-Linked Somatic-Cell Selection and Polycythemia Rubra Vera
- Author
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Lucio Luzzatto, Town Mm, Ogunmola Gb, Esan Gj, and Williams Ck
- Subjects
Genetics ,Polycythemia vera ,Glucosephosphate dehydrogenase ,Somatic cell ,Genetic linkage ,business.industry ,medicine ,General Medicine ,Polycythemia rubra vera ,medicine.disease ,business ,Selection (genetic algorithm) ,X chromosome - Published
- 1984
31. Catalyst development for the ring-opening copolymerisation of epoxides and anhydrides
- Author
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Diment, WT and Williams, CK
- Subjects
Chemistry, Inorganic ,Catalysis - Abstract
This thesis describes the development of a range of catalysts for polyester synthesis via the ring-opening copolymerisation (ROCOP) of epoxides and anhydrides. Chapter 1 provides an introduction to the ROCOP of epoxides and anhydrides, with a particular focus on catalyst development and mechanism. It also introduces the concept of switchable catalysis and describes its application to the synthesis of block polyesters. Chapter 2 details the synthesis and characterisation of a series of monometallic M(III) complexes (M = Al, Cr, Mn, Fe, Co). Their application as catalysts for the ROCOP of cyclohexene oxide (CHO) and phthalic anhydride (PA), and the ROP of decalactone (DL), is explored. The complexes featuring Al(III) and Co(III) are found to be the most active catalysts for these polymerisations. Chapter 3 details the application of the Al(III) and Co(III) complexes synthesised in Chapter 2 to the one-pot switchable catalysis reaction of CHO, PA and DL. Triblock copolymers with molar masses up to 57 kg mol-1 are synthesised. The catalytic activity of these complexes is shown to be significantly higher than previously used commercial salen catalyst systems. Chapter 4 details the synthesis and characterisation of a series of heterodinuclear Al(III)/M(I) (M(I) = Group 1 metal) complexes. All are shown to be excellent catalysts for the ROCOP of CHO and PA, with the Al(III)/K(I) and Al(III)/Rb(I) congeners being the most active. Subsequent kinetic investigations, combined with DFT calculations, result in the proposal of a mechanism where the epoxide is bound and activated by the Al(III) centre and the M(I) ion binds the carboxylate chain end. The scope of the catalysis is established for a wide range of epoxides with anhydrides and CO2. Chapter 5 details the development of an Al(III)/K(I) complex bearing organometallic coligands. It is demonstrated that use of this complex, in conjunction with bifunctional protic chain transfer agents, can yield monodisperse high molar mass polyesters via the ROCOP of vinyl-cyclohexene oxide (vCHO) and PA. The mechanical and thermal properties of the polyesters are investigated to establish the impact of increasing polymer molar mass. Chapter 6 outlines the key developments of this thesis and suggests future avenues for research that build on the work described. Chapter 7 provides experimental details for Chapters 2 – 5. An Appendix is provided that contains supplementary figures and data that support the discussion throughout Chapter 2 – 5.
- Published
- 2022
32. Synergic Catalysis: the Importance of Intermetallic Separation in Co(III)K(I) Catalysts for Ring Opening Copolymerizations.
- Author
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Fiorentini F, Eisenhardt KHS, Deacy AC, and Williams CK
- Abstract
Dinuclear polymerization catalysts can show high activity and control. Understanding how to design for synergy between the metals is important to improving catalytic performances. Three heterodinuclear Co(III)K(I) catalysts, featuring very similar coordination chemistries, are prepared with different intermetallic separations. The catalysts are compared for the ring-opening copolymerization (ROCOP) of propene oxide (PO) with CO
2 or with phthalic anhydride (PA). The catalyst with a fixed, wide intermetallic separation, Lwide CoK(OAc)2 (Co-K = 8.06 Å), shows very high activity for PO/PA ROCOP, but is inactive for PO/CO2 ROCOP. On the other hand, the catalyst with a fixed, narrow intermetallic separation, Lshort CoK(OAc)2 (Co-K, 3.59 Å), shows high activity for PO/CO2 ROCOP, but is much less active for PO/PA ROCOP. A bicomponent catalyst system, comprising a monometallic complex Lmono CoOAc used with an equivalent of KOAc[18-crown-6], shows high activity for both PO/CO2 and PO/PA ROCOP, provided the catalyst concentration is sufficiently high, but underperforms at low catalyst loadings. It is proposed that the two lead catalysts, Lwide CoK(OAc)2 and Lshort CoK(OAc)2 , operate by different mechanisms for PO/PA and PO/CO2 ROCOP. The new wide separation catalyst, Lwide CoK(OAc)2 , shows some of the best performances yet reported for PO/PA ROCOP, and suggests other catalysts featuring larger intermetallic separations should be targeted for epoxide/anhydride copolymerizations.- Published
- 2024
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33. Digital Light Processing to Afford High Resolution and Degradable CO 2 -Derived Copolymer Elastomers.
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Poon KC, Segal M, Bahnick AJ, Chan YM, Gao C, Becker ML, and Williams CK
- Abstract
Vat photopolymerization 3D printing has proven very successful for the rapid additive manufacturing (AM) of polymeric parts at high resolution. However, the range of materials that can be printed and their resulting properties remains narrow. Herein, we report the successful AM of a series of poly(carbonate-b-ester-b-carbonate) elastomers, derived from carbon dioxide and bio-derived ϵ-decalactone. By employing a highly active and selective Co(II)Mg(II) polymerization catalyst, an ABA triblock copolymer (M
n =6.3 kg mol-1 , ÐM =1.26) was synthesized, formulated into resins which were 3D printed using digital light processing (DLP) and a thiol-ene-based crosslinking system. A series of elastomeric and degradable thermosets were produced, with varying thiol cross-linker length and poly(ethylene glycol) content, to produce complex triply periodic geometries at high resolution. Thermomechanical characterization of the materials reveals printing-induced microphase separation and tunable hydrophilicity. These findings highlight how utilizing DLP can produce sustainable materials from low molar mass polyols quickly and at high resolution. The 3D printing of these functional materials may help to expedite the production of sustainable plastics and elastomers with potential to replace conventional petrochemical-based options., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)- Published
- 2024
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34. Lithium Borate Polycarbonates for High-Capacity Solid-State Composite Cathodes.
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Charlesworth T, Yiamsawat K, Gao H, Rees GJ, Williams CK, Bruce PG, Pasta M, and Gregory GL
- Abstract
Improving composite cathode function is key to the success of the solid-state battery. Maximizing attainable cathode capacity and retention requires integrating suitable polymeric binders that retain a sufficiently high ionic conductivity and long-term chemo-mechanical stability of the cathode active material-solid-electrolyte-carbon mixture. Herein, we report block copolymer networks composed of lithium borate polycarbonates and poly(ethylene oxide) that improved the capacity (200 mAh g
-1 at 1.75 mA cm-2 ) and capacity retention (94 % over 300 cycles) of all-solid-state composite cathodes with nickel-rich LiNi0.8 Co0.1 Mn0.1 O2 cathode active material, Li6 PS5 Cl solid electrolyte, and carbon. Tetrahedral B(OR)2 (OH)2 - anions immobilized on the polycarbonate segments provide hydrogen-bonding chain crosslinking and selective Li-counterion conductivity, parameterized by Li-ion transference numbers close to unity (tLi+ ~0.94). With 90 wt % polycarbonate content and a flexible low glass transition temperature backbone, the single-ion conductors achieved high Li-ion conductivities of 0.2 mS cm-1 at 30 °C. The work should inform future binder design for improving the processability of cathode composites towards commercializing solid-state batteries, and allow use in other cell configurations, such as lithium-sulphur cathode designs., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)- Published
- 2024
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35. Cyclic ether and anhydride ring opening copolymerisation delivering new ABB sequences in poly(ester- alt -ethers).
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Kerr RWF, Craze AR, and Williams CK
- Abstract
Poly(ester- alt -ethers) are interesting as they combine the ester linkage rigidity and potential for hydrolysis with ether linkage flexibility. This work describes a generally applicable route to their synthesis applying commercial monomers and yielding poly(ester- alt -ethers) with variable compositions and structures. The ring-opening copolymerisation of anhydrides (A), epoxides (B) and cyclic ethers (C), using a Zr(iv) catalyst, produces either ABB or ABC type poly(ester- alt -ethers). The catalysis is effective using a range of commercial anhydrides (A), including those featuring aromatic, unsaturated or tricyclic monomers, and with different alkylene oxides (epoxides, B), including those featuring aliphatic, alkene or ether substituents. The range of effective cyclic ethers (C) includes tetrahydrofuran, 2,5-dihydrofuran (DHF) or 1,4-bicyclic ether (OBH). In these investigations, the catalyst:anhydride loadings are generally held constant and deliver copolymers with degrees of copolymerisation of 25, with molar mass values from 4 to 11 kg mol
-1 and mostly with narrow dispersity molar mass distributions. All the new copolymers are amorphous, they show the onset of thermal decomposition between 270 and 344 °C and variable glass transition temperatures (-50 to 48 °C), depending on their compositions. Several of the new poly(ester- alt -ethers) feature alkene substituents which are reacted with mercaptoethanol, by thiol-ene processes, to install hydroxyl substituents along the copolymer chain. This strategy affords poly(ether- alt -esters) featuring 30, 70 and 100% hydroxyl substituents (defined as % of monomer repeat units featuring a hydroxyl group) which moderate physical properties such as hydrophilicity, as quantified by water contact angles. Overall, the new sequence selective copolymerisation catalysis is shown to be generally applicable to a range of anhydrides, epoxides and cyclic ethers to produce new families of poly(ester- alt -ethers). In future these copolymers should be explored for applications in liquid formulations, electrolytes, surfactants, plasticizers and as components in adhesives, coatings, elastomers and foams., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)- Published
- 2024
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36. Active forest stewardship benefits priority birds in the New Jersey Pine Barrens.
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Williams CK, Terhune TM 2nd, Parke J, Matseur EA, and Cecil J
- Subjects
- Animals, New Jersey, Birds physiology, Forestry methods, Biodiversity, Songbirds physiology, Forests, Conservation of Natural Resources methods, Ecosystem
- Abstract
Fire suppression has negatively impacted thousands of acres of private and public lands in the United States. As a case study, the New Jersey Pine Barrens (NJPB) are a disturbance driven ecosystem that is experiencing serious ecological implications due to a loss of traditional forest thinning activities such as harvesting for forest products or thinning for wildfire fuel-load reduction measures coupled with a long-standing philosophy of fire suppression and dormant-season prescribed burning. Dense closed-canopy forest conditions, dissimilar to historic open-canopy forests of the NJPB, have reduced abundance and diversity of certain flora and fauna, including regionally imperiled breeding birds. In recent years, active forest stewardship (e.g., thinning, clear-cutting, and burning) has occurred on private and some public lands within the NJPB; however, the impact of such management on breeding birds is unclear due to a paucity of research on this subject within the NJPB. During 2012, 2013, 2016, and 2017, we conducted repeat-visit point counts (n = 1,800) for breeding songbirds across 75 control and 75 treatment sites within the NJPB to assess the influence of forest structure at three strata levels (groundcover, midstory profile, and canopy) on breeding bird communities. Specifically, we constructed a hierarchical community abundance model within a Bayesian framework for Bird Conservation Region (BCR) 30 priority upland birds (n = 12) within three species suites: Forested Upland, Scrub-Shrub (or Young Forest), and Grassland. At the community level, we found a negative relationship between bird abundance and live tree basal area. At the BCR 30 suite level, we found no relationship between Forested Upland suite-level abundance and any of the measured covariates; however, we found a negative relationship between percentage of woody groundcover and Scrub-Shrub suite-level abundance, and negative relationship between horizontal visual obstruction at 2 m above ground level and Grassland suite-level abundance. Furthermore, the two latter species suites exhibited a strong negative relationship with basal area. We recommend active forest stewardship that specifically targets opening the canopy to achieve basal areas between ~0-15 m2/ha via selective thinning, shelter cutting, and small-scale clear cutting. Mechanical treatment and prescribed burning would produce such conditions and have the added benefit of reducing fuel loads across this ~4,500 km2 landscape as well as assisting in carbon defense strategies for the region., Competing Interests: NO authors have competing interests, (Copyright: © 2024 Williams et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
- Published
- 2024
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37. Controlled Carbon Dioxide Terpolymerizations to Deliver Toughened yet Recyclable Thermoplastics.
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Poon KC, Smith ML, and Williams CK
- Abstract
Using CO
2 polycarbonates as engineering thermoplastics has been limited by their mechanical performances, particularly their brittleness. Poly(cyclohexene carbonate) (PCHC) has a high tensile strength (40 MPa) but is very brittle (elongation at break <3%), which limits both its processing and applications. Here, well-defined, high molar mass CO2 terpolymers are prepared from cyclohexene oxide (CHO), cyclopentene oxide (CPO), and CO2 by using a Zn(II)Mg(II) catalyst. In the catalysis, CHO and CPO show reactivity ratios of 1.53 and 0.08 with CO2 , respectively; as such, the terpolymers have gradient structures. The poly(cyclohexene carbonate)- grad -poly(cyclopentene carbonate) (PCHC- grad -PCPC) have high molar masses (86 < Mn < 164 kg mol-1 , ĐM < 1.22) and good thermal stability ( Td > 250 °C). All the polymers are amorphous with a single, high glass transition temperature (96 < Tg < 108 °C). The polymer entanglement molar masses, determined using dynamic mechanical analyses, range from 4 < Me < 23 kg mol-1 depending on the polymer composition (PCHC:PCPC). These polymers show superior mechanical performance to PCHC; specifically the lead material (PCHC0.28 - grad -PCPC0.72 ) shows 25% greater tensile strength and 160% higher tensile toughness. These new plastics are recycled, using cycles of reprocessing by compression molding (150 °C, 1.2 ton m-2 , 60 min), four times without any loss in mechanical properties. They are also efficiently chemically recycled to selectively yield the two epoxide monomers, CHO and CPO, as well as carbon dioxide, with high activity (TOF = 270-1653 h-1 , 140 °C, 120 min). The isolated recycled monomers are repolymerized to form thermoplastic showing the same material properties. The findings highlight the benefits of the terpolymer strategy to deliver thermoplastics combining the beneficial low entanglement molar mass, high glass transition temperatures, and tensile strengths; PCHC properties are significantly improved by incorporating small quantities (23 mol %) of cyclopentene carbonate linkages. The general strategy of designing terpolymers to include chain segments of low entanglement molar mass may help to toughen other brittle and renewably sourced plastics., Competing Interests: The authors declare the following competing financial interest(s): CKW is a director of econic technologies., (© 2024 The Authors. Published by American Chemical Society.)- Published
- 2024
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38. Quantifying CO 2 Insertion Equilibria for Low-Pressure Propene Oxide and Carbon Dioxide Ring Opening Copolymerization Catalysts.
- Author
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Eisenhardt KHS, Fiorentini F, Lindeboom W, and Williams CK
- Abstract
While outstanding catalysts are known for the ring-opening copolymerization (ROCOP) of CO
2 and propene oxide (PO), few are reported at low CO2 pressure. Here, a new series of Co(III)M(I) heterodinuclear catalysts are compared. The Co(III)K(I) complex shows the best activity (TOF = 1728 h-1 ) and selectivity (>90% polymer, >99% CO2 ) and is highly effective at low pressures (<10 bar). CO2 insertion is a prerate determining chemical equilibrium step. At low pressures, the concentration of the active catalyst depends on CO2 pressure; above 12 bar, its concentration is saturated, and rates are independent of pressure, allowing the equilibrium constant to be quantified for the first time ( Keq = 1.27 M-1 ). A unified rate law, applicable under all operating conditions, is presented. As proof of potential, published data for leading literature catalysts are reinterpreted and the CO2 equilibrium constants estimated, showing that this unified rate law applies to other systems.- Published
- 2024
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39. Intercellular Signaling Pathways as Therapeutic Targets for Vascular Dementia Repair.
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Tian M, Kawaguchi R, Shen Y, Machnicki M, Villegas NG, Cooper DR, Montgomery N, Haring J, Lan R, Yuan AH, Williams CK, Magaki S, Vinters HV, Zhang Y, De Biase LM, Silva AJ, and Carmichael ST
- Abstract
Vascular dementia (VaD) is a white matter ischemic disease and the second-leading cause of dementia, with no direct therapy. Within the lesion site, cell-cell interactions dictate the trajectory towards disease progression or repair. To elucidate the underlying intercellular signaling pathways, a VaD mouse model was developed for transcriptomic and functional studies. The mouse VaD transcriptome was integrated with a human VaD snRNA-Seq dataset. A custom-made database encompassing 4053 human and 2032 mouse ligand-receptor (L-R) interactions identified significantly altered pathways shared between human and mouse VaD. Two intercellular L-R systems, Serpine2-Lrp1 and CD39-A3AR, were selected for mechanistic study as both the ligand and receptor were dysregulated in VaD. Decreased Seprine2 expression enhances OPC differentiation in VaD repair. A clinically relevant drug that reverses the loss of CD39-A3AR function promotes tissue and behavioral recovery in the VaD model. This study presents novel intercellular signaling targets and may open new avenues for VaD therapies.
- Published
- 2024
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40. High Molar Mass Polycarbonates as Closed-Loop Recyclable Thermoplastics.
- Author
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Rosetto G, Vidal F, McGuire TM, Kerr RWF, and Williams CK
- Abstract
Using carbon dioxide (CO
2 ) to make recyclable thermoplastics could reduce greenhouse gas emissions associated with polymer manufacturing. CO2 /cyclic epoxide ring-opening copolymerization (ROCOP) allows for >30 wt % of the polycarbonate to derive from CO2 ; so far, the field has largely focused on oligocarbonates. In contrast, efficient catalysts for high molar mass polycarbonates are underinvestigated, and the resulting thermoplastic structure-property relationships, processing, and recycling need to be elucidated. This work describes a new organometallic Mg(II)Co(II) catalyst that combines high productivity, low loading tolerance, and the highest polymerization control to yield polycarbonates with number average molecular weight ( Mn ) values from 4 to 130 kg mol-1 , with narrow, monomodal distributions. It is used in the ROCOP of CO2 with bicyclic epoxides to produce a series of samples, each with Mn > 100 kg mol-1 , of poly(cyclohexene carbonate) (PCHC), poly(vinyl-cyclohexene carbonate) (PvCHC), poly(ethyl-cyclohexene carbonate) (PeCHC, by hydrogenation of PvCHC), and poly(cyclopentene carbonate) (PCPC). All these materials are amorphous thermoplastics, with high glass transition temperatures (85 < Tg < 126 °C, by differential scanning calorimetry) and high thermal stability ( Td > 260 °C). The cyclic ring substituents mediate the materials' chain entanglements, viscosity, and glass transition temperatures. Specifically, PCPC was found to have 10× lower entanglement molecular weight ( Me )n and 100× lower zero-shear viscosity compared to those of PCHC, showing potential as a future thermoplastic. All these high molecular weight polymers are fully recyclable, either by reprocessing or by using the Mg(II)Co(II) catalyst for highly selective depolymerizations to epoxides and CO2 . PCPC shows the fastest depolymerization rates, achieving an activity of 2500 h-1 and >99% selectivity for cyclopentene oxide and CO2 .- Published
- 2024
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41. HIV and COVID-19: two pandemics with significant (but different) central nervous system complications.
- Author
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Magaki S, Zhang T, Han K, Hilda M, Yong WH, Achim C, Fishbein G, Fishbein MC, Garner O, Salamon N, Williams CK, Valdes-Sueiras MA, Hsu JJ, Kelesidis T, Mathisen GE, Lavretsky H, Singer EJ, and Vinters HV
- Abstract
Human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cause significant neurologic disease. Central nervous system (CNS) involvement of HIV has been extensively studied, with well-documented invasion of HIV into the brain in the initial stage of infection, while the acute effects of SARS-CoV-2 in the brain are unclear. Neuropathologic features of active HIV infection in the brain are well characterized whereas neuropathologic findings in acute COVID-19 are largely non-specific. On the other hand, neuropathologic substrates of chronic dysfunction in both infections, as HIV-associated neurocognitive disorders (HAND) and post-COVID conditions (PCC)/long COVID are unknown. Thus far, neuropathologic studies on patients with HAND in the era of combined antiretroviral therapy have been inconclusive, and autopsy studies on patients diagnosed with PCC have yet to be published. Further longitudinal, multidisciplinary studies on patients with HAND and PCC and neuropathologic studies in comparison to controls are warranted to help elucidate the mechanisms of CNS dysfunction in both conditions.
- Published
- 2024
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42. Exploiting Organometallic Chemistry to Functionalize Small Cuprous Oxide Colloidal Nanocrystals.
- Author
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Cowie BE, Mears KL, S'ari M, Lee JK, Briceno de Gutierrez M, Kalha C, Regoutz A, Shaffer MSP, and Williams CK
- Abstract
The ligand chemistry of colloidal semiconductor nanocrystals mediates their solubility, band gap, and surface facets. Here, selective organometallic chemistry is used to prepare small, colloidal cuprous oxide nanocrystals and to control their surface chemistry by decorating them with metal complexes. The strategy is demonstrated using small (3-6 nm) cuprous oxide (Cu
2 O) colloidal nanocrystals (NC), soluble in organic solvents. Organometallic complexes are coordinated by reacting the surface Cu-OH bonds with organometallic reagents, M(C6 F5 )2 , M = Zn(II) and Co(II), at room temperature. These reactions do not disrupt the Cu2 O crystallinity or nanoparticle size; rather, they allow for the selective coordination of a specific metal complex at the surface. Subsequently, the surface-coordinated organometallic complex is reacted with three different carboxylic acids to deliver Cu-O-Zn(O2 CR') complexes. Selective nanocrystal surface functionalization is established using spectroscopy (IR,19 F NMR), thermal gravimetric analyses (TGA), transmission electron microscopy (TEM, EELS), and X-ray photoelectron spectroscopy (XPS). Photoluminescence efficiency increases dramatically upon organometallic surface functionalization relative to that of the parent Cu2 O NC, with the effect being most pronounced for Zn(II) decoration. The nanocrystal surfaces are selectively functionalized by both organic ligands and well-defined organometallic complexes; this synthetic strategy may be applicable to many other metal oxides, hydroxides, and semiconductors. In the future, it should allow NC properties to be designed for applications including catalysis, sensing, electronics, and quantum technologies.- Published
- 2024
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43. Designing a circular carbon and plastics economy for a sustainable future.
- Author
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Vidal F, van der Marel ER, Kerr RWF, McElroy C, Schroeder N, Mitchell C, Rosetto G, Chen TTD, Bailey RM, Hepburn C, Redgwell C, and Williams CK
- Subjects
- Biomass, Carbon Dioxide analysis, Carbon Dioxide chemistry, Carbon Dioxide metabolism, Fossil Fuels, Global Warming prevention & control, Greenhouse Gases analysis, Renewable Energy, Technology economics, Technology legislation & jurisprudence, Technology methods, Technology trends, Environmental Pollution economics, Environmental Pollution legislation & jurisprudence, Environmental Pollution prevention & control, Environmental Pollution statistics & numerical data, Goals, Plastics chemical synthesis, Plastics economics, Plastics metabolism, Plastics supply & distribution, Recycling economics, Recycling legislation & jurisprudence, Recycling methods, Recycling trends, Sustainable Development economics, Sustainable Development legislation & jurisprudence, Sustainable Development trends
- Abstract
The linear production and consumption of plastics today is unsustainable. It creates large amounts of unnecessary and mismanaged waste, pollution and carbon dioxide emissions, undermining global climate targets and the Sustainable Development Goals. This Perspective provides an integrated technological, economic and legal view on how to deliver a circular carbon and plastics economy that minimizes carbon dioxide emissions. Different pathways that maximize recirculation of carbon (dioxide) between plastics waste and feedstocks are outlined, including mechanical, chemical and biological recycling, and those involving the use of biomass and carbon dioxide. Four future scenarios are described, only one of which achieves sufficient greenhouse gas savings in line with global climate targets. Such a bold system change requires 50% reduction in future plastic demand, complete phase-out of fossil-derived plastics, 95% recycling rates of retrievable plastics and use of renewable energy. It is hard to overstate the challenge of achieving this goal. We therefore present a roadmap outlining the scale and timing of the economic and legal interventions that could possibly support this. Assessing the service lifespan and recoverability of plastic products, along with considerations of sufficiency and smart design, can moreover provide design principles to guide future manufacturing, use and disposal of plastics., (© 2024. Springer Nature Limited.)
- Published
- 2024
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44. Characterization of cerebellar amyloid-β deposits in Alzheimer disease.
- Author
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Lopez G, Magaki SD, Williams CK, Paganini-Hill A, and Vinters HV
- Subjects
- Humans, Amyloid beta-Peptides metabolism, Cerebellum pathology, Plaque, Amyloid pathology, Brain pathology, Alzheimer Disease pathology, Cerebral Amyloid Angiopathy pathology
- Abstract
Cerebellar amyloid-β (Aβ) plaques are a component of the diagnostic criteria used in Thal staging and ABC scoring for Alzheimer disease (AD) neuropathologic change. However, Aβ deposits in this anatomic compartment are unique and under-characterized; and their relationship with other pathological findings are largely undefined. In 73 cases of pure or mixed AD with an A3 score in the ABC criteria, parenchymal (plaques) and vascular (cerebral amyloid angiopathy [CAA]) cerebellar Aβ-42 deposits were characterized with respect to localization, morphology, density, and intensity. Over 85% of cases demonstrated cerebellar Aβ-42 parenchymal staining that correlated with a Braak stage V-VI/B3 score (p < 0.01). Among the 63 with cerebellar Aβ-42 deposits, a diffuse morphology was observed in 75% of cases, compact without a central dense core in 32%, and compact with a central dense core in 16% (all corresponding to plaques evident on hematoxylin and eosin staining). Cases with Purkinje cell (PC) loss showed higher proportions of PC layer Aβ-42 staining than cases without PC loss (88% vs 44%, p = 0.02), suggesting a link between Aβ-42 deposition and PC damage. Among all 73 cases, CAA was observed in the parenchymal vessels of 19% of cases and in leptomeningeal vessels in 44% of cases., (© The Author(s) 2023. Published by Oxford University Press on behalf of American Association of Neuropathologists, Inc.)
- Published
- 2024
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45. Alternatives to fluorinated binders: recyclable copolyester/carbonate electrolytes for high-capacity solid composite cathodes.
- Author
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Yeo H, Gregory GL, Gao H, Yiamsawat K, Rees GJ, McGuire T, Pasta M, Bruce PG, and Williams CK
- Abstract
Optimising the composite cathode for next-generation, safe solid-state batteries with inorganic solid electrolytes remains a key challenge towards commercialisation and cell performance. Tackling this issue requires the design of suitable polymer binders for electrode processability and long-term solid-solid interfacial stability. Here, block -polyester/carbonates are systematically designed as Li-ion conducting, high-voltage stable binders for cathode composites comprising of single-crystal LiNi
0.8 Mn0.1 Co0.1 O2 cathodes, Li6 PS5 Cl solid electrolyte and carbon nanofibres. Compared to traditional fluorinated polymer binders, improved discharge capacities (186 mA h g-1 ) and capacity retention (96.7% over 200 cycles) are achieved. The nature of the new binder electrolytes also enables its separation and complete recycling after use. ABA- and AB-polymeric architectures are compared where the A-blocks are mechanical modifiers, and the B-block facilitates Li-ion transport. This reveals that the conductivity and mechanical properties of the ABA-type are more suited for binder application. Further, catalysed switching between CO2 /epoxide A-polycarbonate (PC) synthesis and B-poly(carbonate- r -ester) formation employing caprolactone (CL) and trimethylene carbonate (TMC) identifies an optimal molar mass (50 kg mol-1 ) and composition ( wPC 0.35). This polymer electrolyte binder shows impressive oxidative stability (5.2 V), suitable ionic conductivity (2.2 × 10-4 S cm-1 at 60 °C), and compliant viscoelastic properties for fabrication into high-performance solid composite cathodes. This work presents an attractive route to optimising polymer binder properties using controlled polymerisation strategies combining cyclic monomer (CL, TMC) ring-opening polymerisation and epoxide/CO2 ring-opening copolymerisation. It should also prompt further examination of polycarbonate/ester-based materials with today's most relevant yet demanding high-voltage cathodes and sensitive sulfide-based solid electrolytes., Competing Interests: CKW is a director of Econic Technologies., (This journal is © The Royal Society of Chemistry.)- Published
- 2024
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46. Al(III)/K(I) Heterodinuclear Polymerization Catalysts Showing Fast Rates and High Selectivity for Polyester Polyols.
- Author
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Shellard EJK, Diment WT, Resendiz-Lara DA, Fiorentini F, Gregory GL, and Williams CK
- Abstract
Low molar mass, hydroxyl end-capped polymers, often termed "polyols," are widely used to make polyurethanes, resins, and coatings and as surfactants in liquid formulations. Epoxide/anhydride ring-opening copolymerization (ROCOP) is a controlled polymerization route to make them, and its viability depends upon catalyst selection. In the catalysis, the polyester polyol molar masses and end-groups are controlled by adding specific but excess quantities of diols (vs catalyst), known as the chain transfer agent (CTA), to the polymerizations, but many of the best current catalysts are inhibited or even deactivated by alcohols. Herein, a series of air-stable Al(III)/K(I) heterodinuclear polymerization catalysts show rates and selectivity at the upper end of the field. They also show remarkable increases in activity, with good selectivity and control, as quantities of diol are increased from 10-400 equiv. The reactions are accelerated by alcohols, and simultaneously, their use allows for the production of hydroxy telechelic poly/oligoesters (400 < M
n (g mol-1 ) < 20,400, Đ < 1.19). For example, cyclohexene oxide (CHO)/phthalic anhydride (PA) ROCOP, using the best Al(III)/K(I) catalyst with 200 equiv of diol, shows a turnover frequency (TOF) of 1890 h-1 , which is 4.4× higher than equivalent reactions without any diol (Catalyst/Diol/PA/CHO = 1:10-400:400:2000, 100 °C). In all cases, the catalysis is well controlled and highly ester linkage selective (ester linkages >99%) and operates effectively using bicyclic and/or biobased anhydrides with bicyclic or flexible alkylene epoxides. These catalysts are recommended for future production and application development using polyester polyols., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)- Published
- 2024
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47. Enhancing mitosis quantification and detection in meningiomas with computational digital pathology.
- Author
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Gu H, Yang C, Al-Kharouf I, Magaki S, Lakis N, Williams CK, Alrosan SM, Onstott EK, Yan W, Khanlou N, Cobos I, Zhang XR, Zarrin-Khameh N, Vinters HV, Chen XA, and Haeri M
- Subjects
- Humans, Mitotic Index methods, Artificial Intelligence, Mitosis, Meningioma pathology, Meningeal Neoplasms pathology
- Abstract
Mitosis is a critical criterion for meningioma grading. However, pathologists' assessment of mitoses is subject to significant inter-observer variation due to challenges in locating mitosis hotspots and accurately detecting mitotic figures. To address this issue, we leverage digital pathology and propose a computational strategy to enhance pathologists' mitosis assessment. The strategy has two components: (1) A depth-first search algorithm that quantifies the mathematically maximum mitotic count in 10 consecutive high-power fields, which can enhance the preciseness, especially in cases with borderline mitotic count. (2) Implementing a collaborative sphere to group a set of pathologists to detect mitoses under each high-power field, which can mitigate subjective random errors in mitosis detection originating from individual detection errors. By depth-first search algorithm (1) , we analyzed 19 meningioma slides and discovered that the proposed algorithm upgraded two borderline cases verified at consensus conferences. This improvement is attributed to the algorithm's ability to quantify the mitotic count more comprehensively compared to other conventional methods of counting mitoses. In implementing a collaborative sphere (2) , we evaluated the correctness of mitosis detection from grouped pathologists and/or pathology residents, where each member of the group annotated a set of 48 high-power field images for mitotic figures independently. We report that groups with sizes of three can achieve an average precision of 0.897 and sensitivity of 0.699 in mitosis detection, which is higher than an average pathologist in this study (precision: 0.750, sensitivity: 0.667). The proposed computational strategy can be integrated with artificial intelligence workflow, which envisions the future of achieving a rapid and robust mitosis assessment by interactive assisting algorithms that can ultimately benefit patient management., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
48. Toughening CO 2 -Derived Copolymer Elastomers Through Ionomer Networking.
- Author
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Poon KC, Gregory GL, Sulley GS, Vidal F, and Williams CK
- Published
- 2024
- Full Text
- View/download PDF
49. Justice for all.
- Author
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Williams CK
- Published
- 2024
- Full Text
- View/download PDF
50. Hyaline protoplasmic astrocytopathy in epilepsy.
- Author
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Magaki S, Haeri M, Szymanski LJ, Chen Z, Diaz R, Williams CK, Chang JW, Ao Y, Newell KL, Khanlou N, Yong WH, Fallah A, Salamon N, Daniel T, Cotter J, Hawes D, Sofroniew M, and Vinters HV
- Subjects
- Child, Adult, Humans, Filamins metabolism, Hyalin, Brain pathology, Astrocytes pathology, Drug Resistant Epilepsy, Epilepsy
- Abstract
Hyaline protoplasmic astrocytopathy (HPA) describes a rare histologic finding of eosinophilic, hyaline cytoplasmic inclusions in astrocytes, predominantly in the cerebral cortex. It has mainly been observed in children and adults with a history of developmental delay and epilepsy, frequently with focal cortical dysplasia (FCD), but the nature and significance of these inclusions are unclear. In this study, we review the clinical and pathologic features of HPA and characterize the inclusions and brain tissue in which they are seen in surgical resection specimens from five patients with intractable epilepsy and HPA compared to five patients with intractable epilepsy without HPA using immunohistochemistry for filamin A, previously shown to label these inclusions, and a variety of astrocytic markers including aldehyde dehydrogenase 1 family member L1 (ALDH1L1), SRY-Box Transcription Factor 9 (SOX9), and glutamate transporter 1/excitatory amino acid transporter 2 (GLT-1/EAAT2) proteins. The inclusions were positive for ALDH1L1 with increased ALDH1L1 expression in areas of gliosis. SOX9 was also positive in the inclusions, although to a lesser intensity than the astrocyte nuclei. Filamin A labeled the inclusions but also labeled reactive astrocytes in a subset of patients. The immunoreactivity of the inclusions for various astrocytic markers and filamin A as well as the positivity of filamin A in reactive astrocytes raise the possibility that these astrocytic inclusions may be the result of an uncommon reactive or degenerative phenomenon., (© 2023 The Authors. Neuropathology published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Neuropathology.)
- Published
- 2023
- Full Text
- View/download PDF
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