11 results on '"Hayden, Cameron"'
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2. Synchronization of follicle wave emergence before ovarian superstimulation with FSH and ovum pick-up improves in vitro embryo production in pregnant heifers
- Author
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Hayden, Cameron B., Sala, Rodrigo V., Absalón-Medina, Victor A., Motta, Jessica C.L., Pereira, Daniela, Moreno, Juan F., and García-Guerra, Alvaro
- Published
- 2022
- Full Text
- View/download PDF
3. PSXII-20 Ovarian dynamics and fertility in beef cows administered a 5-day or 6-day CO-Synch protocol for timed artificial insemination
- Author
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Crist, Alexandria E, primary, Motta, Jessica Cristina Lemos, additional, Hayden, Cameron, additional, Duran, Benjamin, additional, and Mussard, Martin, additional
- Published
- 2021
- Full Text
- View/download PDF
4. Systemic absorption of sunscreen after topical application
- Author
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Hayden, Cameron G J, Roberts, Michael S, and Benson, Heather A E
- Published
- 1997
5. Enhancing Capacitance of Electrochemical Capacitors By Multi-Layer Electrodeposition of Manganese Dioxide
- Author
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Fahad Mujammami, Hayden Cameron, Yaser Beyad, and Scott W Donne
- Abstract
Energy usage has increased substantially in recent years with an estimated global energy production predicted to reach 28 TW by 2050. Currently, approximately 85% of energy is generated from the combustion of fossil fuels such as coal, petroleum products and natural gas, which are neither sustainable nor eco-friendly. Renewable sources such as solar, wind and hydrothermal are alternatives to replace the current non-renewable primary energy source. This renewable energy dominated future leads to a world where energy storage systems need to be efficient to sustain the heavy loads because of increasing energy demands. Currently any renewable energy source must be paired with an energy storage device such as, a capacitor, battery, flywheel, pumped hydro or compressed air, to utilize both the energy produced and to increase the efficiency of the device. As renewable energy devices become more powerful and efficient, so must the energy storage device paired to it. Thin-film MnO2 deposits have exhibited properties that are highly desirable for use as ultracapacitors, due to its exceptional performance, high abundance, cheap production costs and non-toxicity. In this work the layered MnO2 thin-films were produced using a duty cycle method in which a constant potential is pulsed throughout the duration of the electrodeposition, this allowed for both the number and duration of pulses and rests to be varied which has ultimately enabled studying the effect of those factors on the performance of the MnO2 thin-films. The performance of the MnO2 thin-films were then analysed by sweeping the potential between 0.2-0.8 V vs SCE in a solution of 0.5 M K2SO4 for 250 times to observe cycling efficiency and morphological changes after cycles.
- Published
- 2019
6. Chemically Synthesised ϒ-MnO2, and β-MnO2/Single Wall Carbon Nanotube Composites As a Promising High Capacity Cathode Materials for Lithium-Ion Batteries
- Author
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Zahoor Ahmed, Hayden Cameron, and Scott W. Donne
- Subjects
Nanocomposite ,Materials science ,chemistry.chemical_element ,Carbon nanotube ,Electrochemistry ,Cathode ,law.invention ,Ion ,chemistry ,Chemical engineering ,law ,Lithium ,Cyclic voltammetry ,Faraday efficiency - Abstract
This work reports the ϒ-MnO2, and β-MnO2 single wall carbon nanotube (SWCNT) nanocomposite cathode material synthesised successfully by chemical method for lithium-ion batteries. The electrochemical properties galvanostatic charge-discharge, cycle ability, rate performance and cyclic voltammetry were greatly enhanced by using the (SWCNT) composite cathode as a comparison to the pristine ϒ-MnO2, and β-MnO2. As a consequence, the modified (SWCNT) composite cathode material exhibits superior initial discharge capacity 255 mAh g-1 at 0.1C with coulombic efficiency of 99.22% and 118 mAh g-1 at 1C with a capacity retention (coulombic efficiency) of 95.5% (99.9%) after 100 cycles in the potential window of 2.0-4.5V (vs Li/Li+). In comparison pristine β-MnO2 exhibit only 169 mAh g-1 at 0.1C, corresponding to lower initial coulombic efficiency of 97% and 73 mAh g-1 at 1C with capacity retention (coulombic efficiency) of 71.4% (92%) after 100 cycles. The significant improvement in the de-/lithiation kinetic can be accredited to the enhancement in apparent lithium ion diffusion coefficient and electronic conductivity making it more applicable in high power commercialization.
- Published
- 2019
7. Efficacy of methods to synchronize follicular wave emergence in pregnant heifers.
- Author
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Hayden, Cameron B., Motta, Jessica C.L., Sala, Rodrigo V., Bello, Nora M., Coutinho da Silva, Marco A., and García-Guerra, Alvaro
- Abstract
The objective of the present study was to evaluate the efficacy of various methods for synchronization of follicular wave emergence (FWE) in pregnant heifers. Pregnant (60 d of gestation) Holstein heifers (n = 86) arranged in cohorts were randomly assigned to be administered: GnRH (172 µg of gonadorelin acetate); hCG (3,300 IU of human chorionic gonadotropin); FA (follicular ablation of follicles >5 mm); or saline (Control). Ultrasonography was performed to determine ovulation and emergence of a new follicular wave. Data were analyzed using generalized linear mixed models with treatment as a fixed effect and cohort as a random effect. Ovulatory response was greater for hCG (81.0%; 95% CI: 58.0–92.9) than GnRH-treated (50.0%; 95% CI: 28.8–71.2) heifers, whereas ovulation was not observed for heifers in the FA or Control groups. Heifers in the FA group had a shorter (34.8 ± 1.7 h) interval from treatment to FWE compared with heifers in the hCG (51.8 ± 5.3 h), GnRH (56.8 ± 5.3 h) and Control (61.4 ± 9.8 h) groups. Furthermore, treatments differed in variability of time to FWE, whereby FA-treated heifers had less variable, more consistent responses than hCG and GnRH heifers. These groups were, in turn, less variable in time to FWE than heifers in the Control group. Synchronization of FWE efficacy was greater in FA (97.6%; 95% CI: 69.8–99.9) and hCG-treated (75.0%; 95% CI: 52.8–89.0) heifers than Control (27.5%; 95% CI: 12.2–50.9) heifers, while there was marginal evidence for a difference between GnRH (69.1%; 95% CI: 46.4–85.2) and Control heifers. In conclusion, there was no evidence for differences in FWE synchronization efficacy between hCG, GnRH and FA. Nevertheless, FA resulted in a shorter and less variable interval from treatment to FWE thus providing a more precise control of follicular development.
- Published
- 2024
- Full Text
- View/download PDF
8. Simultaneous Analysis of Thin-Film MnO2 Deposits Using Cyclic Voltammetry (CV), Step Potential Electrochemical Spectroscopy (SPECS), Electrochemical Quartz Crystal Microbalance (EQCM) and Electrochemical Impedance Spectroscopy (EIS)
- Author
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Hayden Cameron and Scott W Donne
- Abstract
As a population the reliance on portable electronics and rapid development in electric vehicles in order to combat global warming has caused researchers to search for materials that exhibit excellent energy storage properties. Thin film manganese dioxide deposits have been observed to exhibit excellent behaviour and have become a popular research material for electrochemical capacitors and batteries. In this project a method was developed in which the mass change for a thin film of manganese dioxide during electrochemical experiments could be observed. Manganese dioxide was electrodeposited onto a platinum EQCM electrode allowing for the mass change throughout the deposition process to be recorded providing a better understanding of the electrodeposition mechanism. Once the manganese dioxide was prepared the EQCM was used as a working electrode throughout further electrochemical testing which included cyclic voltammetry (CV), step potential electrochemical spectroscopy (SPECS), and electrochemical impedance spectroscopy (EIS) while recording the mass change throughout each test. Cyclic voltammetry was conducted with a 25 mV/s sweep in 0.5 M K2SO4 from 0-0.8V vs SCE for 250 cycles. By doing this the capacitive performance of the material was determined, and by recording the mass change throughout the experiment it was possible to determine if there were faradaic, non-faradaic process occurring on the surface of the electrode affecting the charge storage mechanism and to observe sample stability throughout cycling. SPECS and EIS immediately followed the cycling which allowed for the observation of the maximum charge storage capability of the material and the mechanism in which the material stores charge. The impedance data allows for the analysis of the charge transfer mechanism and the various interfacial resistance and capacitance at the electrode-electrolyte interface. This combination of techniques has allowed for significantly greater understanding of the processes that the electrode materials are undergoing throughout the experiments and can be used as a powerful tool in various aspects of electrochemical analysis.
- Published
- 2017
9. Simultaneous Analysis of Thin-Film Manganese Dioxide Deposits Using Eqcm, Cyclic Voltammetry, Step Potential Electrochemical Spectroscopy and Electrochemical Impedance Spectroscopy
- Author
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Scott W Donne and Hayden Cameron
- Abstract
As a population the reliance on portable electronics and rapid development in electric vehicles in order to combat global warming has caused researchers to search for materials that exhibit excellent energy storage properties. Thin film MnO2 deposits have been observed to exhibit these properties and has become a popular research material for capacitors and batteries. In this project a method was developed in which the mass change for a thin film of MnO2 during electrochemical experiments could be observed. It was conducted by depositing MnO2 onto a platinum quartz crystal, by doing this it allowed for the mass change throughout the deposition process to be recorded providing a better understanding of the deposition mechanism. Once the MnO2 was deposited the EQCM was used as a working electrode throughout further electrochemical testing which included cyclic voltammetry (CV), step potential electrochemical spectroscopy (SPECS), and electrochemical impedance spectroscopy (EIS) while recording the mass change throughout each test. Cyclic voltammetry was conducted with a 25mV sweep from 0 - 0.8V for 250 cycles. By doing this the capacitive performance of the material was determined, however, by recording the mass change throughout the experiment it was possible to determine if there were faradaic, non-faradaic process occurring on the surface of the electrode affecting the charge storage mechanism and to observe sample stability throughout cycling. SPECS and EIS immediately followed the cycling which allowed for the observation of the maximum charge storage capability of the material and the mechanism in which the material stores energy. The impedance data allows for the analysis of the charge transfer mechanism and the various interfacial resistance and capacitance at the electrode-electrolyte interface. This technique has allowed for significantly greater understanding of the processes that the electrode materials are undergoing throughout the experiments and can be used as a powerful tool in various aspects of electrochemical analysis. Figure 1
- Published
- 2016
10. Optimization of ovarian superstimulation before ovum pick-up and in vitro embryo production in pregnant cattle
- Author
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Hayden, Cameron
- Subjects
- Animal Sciences, Bovine, ovarian superstimulation, ovum pick-up, in vitro embryo production, follicle stimulating hormone, follicle wave emergence, pregnant, cattle
- Abstract
This thesis focuses on the assessment of strategies directed at the optimization of ovum pick-up (OPU) and in vitro embryo production (IVEP) in pregnant cattle. The primary determinants for the success of OPU/IVEP are the number and quality of oocytes recovered after OPU, which in turn are affected by the number and developmental stage in the follicle population from which oocytes are collected. The objectives, therefore, were to: 1) evaluate the effect of use and dose of follicle stimulating hormone (FSH) on ovarian response and IVEP; 2) investigate the effect of synchronization of timing of follicle wave emergence (FWE) among females before ovarian superstimulation on ovarian response and IVEP; and 3) determine the efficacy of various methods for synchronizing FWE. In the first experiment, presented in Chapter 3, pregnant heifers (n = 48) were assigned to receive 0, 160 or 300 mg of porcine FSH (p-FSH) administered in four decreasing doses beginning at time of FWE. Ultrasonography, to evaluate ovarian response preceded OPU, which was performed 40 h after the last p-FSH administration and cumulus oocyte complexes (COC) that were collected were subjected to IVEP procedures. Total number of follicles at OPU and number of both total and viable COCs increased linearly (P < 0.0001) with increasing p-FSH dose. Cleavage percentage, number of cleaved oocytes, blastocyst percentage and number of blastocysts increased linearly (P < 0.0001) with increasing p-FSH dose. In the second experiment, presented in Chapter 4, pregnant heifers (n = 64) were randomly assigned to initiate superstimulatory treatments, consisting of administration of 160 mg of p-FSH, after synchronization of timing of FWE or at random stages of the follicular wave. Synchronization of timing of FWE resulted in a greater (P < 0.01) percentage of medium sized follicles, as well as greater (P < 0.01) cleavage and blastocyst percentage, which subsequently led to an increased (P < 0.01) number of blastocysts produced. In the third experiment, presented in Chapter 5, pregnant heifers (n = 86) were randomly assigned to be administered gonadotropin releasing hormone (GnRH); human chorionic gonadotropin (hCG); follicle ablation (FA); or remain untreated (Control). Ovarian dynamics were evaluated using transrectal ultrasonography. Efficacy of synchronizing the timing of FWE was greater (P < 0.05) for FA and hCG-treated than Control heifers, while there was marginal evidence (P = 0.06) for a difference between GnRH-treated and Control heifers. Conversely, heifers in the FA-treated group had a shorter and less variable (P < 0.05) interval from treatment to FWE than Control, hCG and GnRH-treated heifers. In conclusion, synchronization of timing of FWE and subsequently inducing ovarian superstimulation with exogenous FSH before OPU/IVEP in pregnant cattle improves ovarian response and oocyte developmental competence leading to greater embryo production. Furthermore, synchronization of timing of FWE using hCG or GnRH has similar efficacy as that occurring with FA treatment, however, FA provides a more precise control of follicle development which may prove beneficial for use before ovarian superstimulation and OPU/IVEP.
- Published
- 2022
11. Ovarian dynamics and fertility in beef cows administered a 5-day or 6-day CO-Synch protocol for timed artificial insemination.
- Author
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Crist, Alexandria E., Motta, Jessica Cristina Lemos, Hayden, Cameron, Duran, Benjamin, and Mussard, Martin
- Subjects
OVULATION ,ESTRUS ,ARTIFICIAL insemination ,CATTLE fertility ,PROGESTERONE ,COWS ,CORPUS luteum ,FERTILITY ,GONADOTROPIN releasing hormone - Abstract
The 5-day CO-Synch is an extensively used TAI protocol; however, it requires multiple administrations of prostaglandin F2a (PGF). The objective of the present study was to evaluate the effect of increasing progesterone (P4) device insertion from 5 to 6 days during a TAI protocol on ovarian dynamics and fertility in beef cows. Suckled beef cows (n = 867) at six locations were randomly assigned to either a 5-day or 6-day CO-Synch. Cows received an intravaginal P4 device (CIDR, Zoetis) and 100 µg of gonadorelin acetate (GnRH, Parnell) on d-9 (6-day) or d-8 (5-day). On d-3 CIDR's were removed, an estrus detection patch applied (Estrotect, Rockway Inc.) and either one (6-day) or two (5-day) doses of PGF (500 µg of cloprostenol sodium, Estroplan, Parnell) was administered. On d0 (72 h after CIDR removal) all cows received 100 µg of GnRH, estrus expression was evaluated, and AI was performed. Pregnancy was determined by ultrasonography 34 days after TAI. Ovarian dynamics were evaluated in a subset of animals (n = 20) between d-3 and d7 to determine preovulatory follicle size, time of ovulation and corpus luteum (CL) size. Data were analyzed using generalized linear mixed models (SAS 9.4). Cows in the 6-day group tended (P = 0.09) to have a larger maximum follicle diameter (16.2±0.4mm) than cows in the 5-day group (15.0±0.6mm). In addition, CL volume on d7 was greater (P = 0.01) in the 6-day (4302±495mm3) than 5-day (2406±455mm3) group. There were, however, no differences (P = 0.15) in the interval between CIDR removal and ovulation. Cows assigned to the 6-day group had greater (P < 0.05) estrus expression [56.1% (215/385) vs 41.5% (161/388)] and pregnancy rate [54.6% (236/438) vs 47.4% (207/435)] than cows in the 5-day group. In conclusion, extension of the period of P4 device insertion in a prolonged proestrus protocol increases preovulatory follicle size, estrous expression, and fertility to TAI. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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