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Babauta JT, Beasley CA, Beyenal H. Investigation of Electron Transfer by Geobacter sulfurreducens Biofilms by using an Electrochemical Quartz Crystal Microbalance. ChemElectroChem 2014; 1:2007-2016. [PMID: 27525205 PMCID: PMC4964883 DOI: 10.1002/celc.201402127] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 06/17/2014] [Indexed: 01/05/2023]
Abstract
Both the short- and long-term electron-transfer processes of electrode-respiring Geobacter sulfurreducens biofilms are demonstrated by using an electrochemical quartz crystal microbalance (QCM). The QCM monitors the frequency shift from the initial resonant frequency (background) in real time, while the current increases, because of biofilm growth. In the short term, the frequency shift is linear with respect to current for the biofilm. In long-term biofilm growth up to the exponential phase, a second linear region of frequency shift with respect to current is observed. In addition to the frequency shift response at constant polarization, the frequency shift response is coupled to cyclic voltammetry experiments. During cyclic voltammetry, a reproducible, negative increase in frequency shift is observed at oxidizing potentials. The results suggest that a QCM can be used in applications in which it is useful to find the most efficient current producer.
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Affiliation(s)
- Jerome T Babauta
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering PO Box 646515, Washington State University, Pullman, WA 99164-6515 (USA) E-mail:
| | | | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering PO Box 646515, Washington State University, Pullman, WA 99164-6515 (USA) E-mail:
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Hillman AR, Ryder KS, Zaleski CJ, Ferreira V, Beasley CA, Vieil E. Application of the combined electrochemical quartz crystal microbalance and probe beam deflection technique in deep eutectic solvents. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.04.062] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Exogenous plant growth regulators can substitute for pollination, fertilization, and subsequent embryo development in cotton. Isolated, unfertilized, immature ovules enlarge in the presence of kinetin, and both enlarge and produce fibers in the presence of indoleacetic acid or gibberellic acid or both. An extract of germinating cotton pollen qualitatively mimics the effect of exogenous hormones.
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Sardar R, Beasley CA, Murray RW. Interfacial Ion Transfers between a Monolayer Phase of Cationic Au Nanoparticles and Contacting Organic Solvent. J Am Chem Soc 2010; 132:2058-63. [DOI: 10.1021/ja909584p] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rajesh Sardar
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Christopher A. Beasley
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Royce W. Murray
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
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Fields-Zinna CA, Sardar R, Beasley CA, Murray RW. Electrospray Ionization Mass Spectrometry of Intrinsically Cationized Nanoparticles, [Au144/146(SC11H22N(CH2CH3)3+)x(S(CH2)5CH3)y]x+. J Am Chem Soc 2009; 131:16266-71. [DOI: 10.1021/ja906976w] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | - Rajesh Sardar
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Christopher A. Beasley
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Royce W. Murray
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
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Beasley CA, Murray RW. Voltammetry and redox charge storage capacity of ferrocene-functionalized silica nanoparticles. Langmuir 2009; 25:10370-10375. [PMID: 19505118 DOI: 10.1021/la901050t] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We describe the electrochemistry of 15 nm diameter silica nanoparticles densely functionalized with ferrocene (FcSiO(2)) through siloxane couplings. Each nanoparticle bears approximately 600 Fc sites, as measured by potentiometric titration (590 Fc) and diffusion-controlled voltammetry (585 Fc) and estimated by XPS (630 Fc). The nanoparticle ferrocene coverage amounts to ca. a complete monolayer of ferrocene sites, which react electrochemically without mutual interactions and which are apparently fully accessible for diffusion-controlled electrode reactions. Diffusion-controlled voltammetry of the FcSiO(2) nanoparticles was observed in dilute methanol dispersions and in more concentrated slurry phases formed in methanol/acetonitrile mixtures. Electrochemical studies reveal interesting behavior in the dilute and more concentrated solutions. Because of the large nanoparticle surface area/volume ratio, the ferrocene-coated silica nanoparticles are capable of storing up to 5 x 10(7) C/m(3) of redox charge as dry phases and 6 x 10(5) C/m(3) in the concentrated slurries.
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Affiliation(s)
- Christopher A Beasley
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
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Sardar R, Beasley CA, Murray RW. Ferrocenated Au Nanoparticle Monolayer Adsorption on Self-Assembled Monolayer-Coated Electrodes. Anal Chem 2009; 81:6960-5. [DOI: 10.1021/ac9010364] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rajesh Sardar
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina, 27599
| | - Christopher A. Beasley
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina, 27599
| | - Royce W. Murray
- Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, North Carolina, 27599
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Beasley CA, Hwang TL, Fliszar K, Abend A, McCollum DG, Reed RA. Identification of impurities in ivermectin bulk material by mass spectrometry and NMR. J Pharm Biomed Anal 2006; 41:1124-34. [PMID: 16554137 DOI: 10.1016/j.jpba.2006.02.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 02/07/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022]
Abstract
The identification and characterization of four process impurities in bulk ivermectin and four process impurities in bulk avermectin, using a combination of MS and NMR, are discussed herein. These process impurities were shown to be 24-demethyl H2B1a, 3'-demethyl H2B1a, 3''-demethyl H2B1a and 24a-hydroxy B2a isomer. The impurities were shown to be process impurities and are present in avermectin bulk also.
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Affiliation(s)
- Christopher A Beasley
- Pharmaceutical Research and Development, Merck Research Laboratories, Merck & Co., Inc., WP78-210, West Point, PA 19486, USA
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Beasley CA, Shaw J, Zhao Z, Reed RA. Development and validation of a stability indicating HPLC method for determination of lisinopril, lisinopril degradation product and parabens in the lisinopril extemporaneous formulation. J Pharm Biomed Anal 2005; 37:559-67. [PMID: 15740917 DOI: 10.1016/j.jpba.2004.11.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2004] [Revised: 11/10/2004] [Accepted: 11/12/2004] [Indexed: 11/18/2022]
Abstract
The purpose of the research described herein was to develop and validate a stability-indicating HPLC method for lisinopril, lisinopril degradation product (DKP), methyl paraben and propyl paraben in a lisinopril extemporaneous formulation. The method developed in this report is selective for the components listed above, in the presence of the complex and chromatographically rich matrix presented by the Bicitra and Ora-Sweet SF formulation diluents. The method was also shown to have adequate sensitivity with a detection limit of 0.0075 microg/mL (0.03% of lisinopril method concentration). The validation elements investigated showed that the method has acceptable specificity, recovery, linearity, solution stability, and method precision. Acceptable robustness indicates that the assay method remains unaffected by small but deliberate variations, which are described in ICH Q2A and Q2B guidelines.
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Affiliation(s)
- Christopher A Beasley
- Pharmaceutical Research and Development, Merck Research Laboratories, Merck & Co. Inc., WP78-210, West Point, PA 19486, USA.
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Thompson KC, Zhao Z, Mazakas JM, Beasley CA, Reed RA, Moser CL. Characterization of an extemporaneous liquid formulation of lisinopril. Am J Health Syst Pharm 2003; 60:69-74. [PMID: 12533979 DOI: 10.1093/ajhp/60.1.69] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The stability of lisinopril in an extemporaneously prepared suspension stored at or below 25 degrees C for 28 days under ambient light exposure was studied. A formulation of 1-mg/mL oral suspension was prepared from commercially available 20-mg lisinopril tablets, using Bicitra and Ora-Sweet SF as the compounding vehicles to make a final volume of 200 mL. Individual samples, stored in 8-oz amber polyethylene terephthalate bottles, were used for each test performed. All samples were stored at 25 degrees C. Appropriateness of the extemporaneous preparation method was performed by shaking three lots of each suspension for 30, 60, and 90 seconds. To test the robustness and reproducibility of the method, two chemists prepared the suspensions from the same three lots of lisinopril tablets. Chemical and physical stability were established by analyzing duplicate samples at time zero and after one, two, four, and six weeks. The solubility of lisinopril was tested from suspensions stored for four weeks. In-use stability was also examined over four weeks. Photochemical stability was examined by exposing three batches of the suspension to maximum light stress in accordance with the International Conference on Harmonization. Antimicrobial-effectiveness testing was also conducted with freshly prepared suspensions and suspensions stored for six weeks. The preparation method used was appropriate and effective. Lisinopril is fully dissolved in the suspension matrix. Satisfactory chemical, physical, and microbiological results were obtained after the suspensions were stored for six weeks at 25 degrees C and 35% relative humidity. Lisinopril suspensions extemporaneously prepared from tablets are stable for at least four weeks when stored at or below 25 degrees C under ambient light exposure.
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Affiliation(s)
- Karen C Thompson
- Merck Research Laboratories, P.O. Box 4, WP78-302, West Point, PA 19486, USA.
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Beasley CA, Egli MA, Chang SR. Independent control of fiber development and nitrate reduction in cultured cotton ovules. Plant Physiol 1979; 63:57-60. [PMID: 16660693 PMCID: PMC542765 DOI: 10.1104/pp.63.1.57] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Several lines of evidence implicate ammonium as an important factor in the growth and development of cotton (Gossypium hirsutum L.) ovules cultured in vitro. For example, ovules cultured at 28 C require indoleacetic acid (IAA) and either ammonium or gibberellic acid (GA(3)) in the medium for fiber development, whereas ovules cultured at 34 C require only IAA. Because of this effect of ammonium supply, it seemed possible that hormones or increased temperature were also promoting the availability of reduced nitrogen by induction of increased nitrate reductase activity in the ovules. This possibility was tested.In vivo, where ovules received mostly reduced nitrogen and very little nitrate, they did not display appreciable nitrate reductase activity even when nitrate was forced into the ovary wall by transpiration. After initiation of culture, nitrate became freely available to ovules and their nitrate reductase activity increased rapidly. Treatment with ammonium, GA(3), IAA, or increased temperature had no effect upon this induction. It is concluded that ammonium, hormone, and temperature effects on fiber development are independent of the availability of reduced nitrogen as a general substrate for growth.
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Affiliation(s)
- C A Beasley
- Department of Plant Sciences, University of California, Riverside, California 92521
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Abstract
Unfertilized cotton ovules, cultured in vitro, produced fiber in response to indoleacetic acid (IAA) and/or gibberellic acid (GA(3)). Of the two hormones, IAA produced the greater amount of fiber per ovule, and the effect of both hormones applied simultaneously was approximately additive. Depending upon in vitro culture temperature, a variable number of unfertilized cotton ovules produced fiber in response to 5 mum IAA. The response to IAA was "all or none" for each ovule. The percentage of ovules responding to 5 mum IAA ranged from zero at 28 C to 100 at 34 C. The ability to respond at nonpermissive culture temperatures (i.e. 28 to 30 C) was markedly increased by including 2.5 mm NH(4)NO(3) in the KNO(3)-based medium or by increasing concentrations of IAA. The inclusion of NH(4) (+) in the basal culture medium provided only an increased percentage of ovules producing fiber in the presence of IAA, but did not increase fiber production per ovule. Temperature, like GA(3), increased both the number of ovules producing fiber in response to IAA and the amount of fiber produced per ovule.
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Affiliation(s)
- C A Beasley
- Department of Plant Sciences, University of California, Riverside, California 92502
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Dhindsa RS, Beasley CA, Ting IP. Effects of abscisic acid on in vitro growth of cotton fiber. Planta 1976; 130:197-201. [PMID: 24424599 DOI: 10.1007/bf00384420] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/1975] [Accepted: 01/26/1976] [Indexed: 05/10/2023]
Abstract
Abscisic acid (ABA) inhibits in vitro growth of cotton (Gossypium hirsutum L.) fiber and is effective only when applied during the first four days of culture started on the day of anthesis. Abscisic acid causes a small increase in potassium uptake by the ovules and also enhances leakage of potassium from them. During their period of rapid growth, fibers produced by ABA-treated ovules have a higher potassium content and a lower malate content as compared to fibers on untreated control ovules. Results are discussed in the light of earlier reports on the in vitro growth of cotton fiber and effects of abscisic acid on other plant tissues. It is suggested that ABA inhibits fiber growth, in part, by interfering with malate metabolism.
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Affiliation(s)
- R S Dhindsa
- Department of Biology, University of California, 92502, Riverside, California, USA
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Abstract
Kinetics and osmoregulation of cotton (Gossypium hirsutum L.) fiber growth (primarily extension) have been studied. Growth is dependent on turgor pressure in the fiber. It is inhibited when a decrease in the water potential of the culture medium due to an addition of Carbowax 6000, equals the turgor pressure of the fiber. Potassium and malate accumulate in the fiber and reach peak levels when the growth rate is highest. Maximum concentrations of potassium and malate reached in the fiber can account for over 50% of the osmotic potential of the fiber. As growth slows down, levels of potassium and malate decrease and turgor pressure declines. Cotton ovules are capable of fixing H(14)CO(3) (-) in the dark, predominantly into malate. Fiber growth is inhibited by the absence of potassium and/or atmospheric CO(2). We suggest that potassium and malate act as osmoregulatory solutes and that malate, at least in part, arises from dark CO(2) fixation reactions.
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Affiliation(s)
- R S Dhindsa
- Department of Biology, University of California, Riverside, California 92502
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Birnbaum EH, Beasley CA, Dugger WM. Boron Deficiency in Unfertilized Cotton (Gossypium hirsutum) Ovules Grown in Vitro. Plant Physiol 1974; 54:931-5. [PMID: 16659003 PMCID: PMC366636 DOI: 10.1104/pp.54.6.931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Boron deficiency and phytohormone interactions have been studied in unfertilized cotton (Gossypium hirsutum) ovules grown in vitro. Such ovules required exogenous indoleacetic acid and/or gibberellic acid for fiber elongation. Boron also was required for maintenance of fiber elongation and normal morphogenesis throughout 14 days of culture. The amount of exogenous boron necessary for maximum fiber elongation varied among experiments, presumably in relation to endogenous boron levels at anthesis. Some ovular epidermal cells distant from the liquid medium could be induced to elongate into fiber even after 6 days in boron-deficient medium in response to the later addition of boron.Boron deficiency, in the presence of exogenous indoleacetic acid, was characterized by lack of fiber development on the inundated ovular surface and reduced fiber growth on the ovular surface exposed to air. In the presence of gibberellic acid, boron deficiency was characterized by complete absence of fiber and callusing of the entire ovular surface. When both indoleacetic acid and gibberellic acid were added, the lack of boron resulted in proliferation of callus laterally and upward from the inundated epidermis, accumulation of brown pigments (presumably phenolic compounds) in the callus, and restriction of fiber to a small area of the upper ovular surface.
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Affiliation(s)
- E H Birnbaum
- Department of Biology, University of California, Riverside, California 92502
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Abstract
The capacity for biosynthesis of hot alkali-insoluble products using uridine diphosphate (UDP)-glucose and guanosine diphosphate (GDP)-glucose as substrate has been studied in isolated cotton fibers harvested at various stages of development following anthesis. During the period of rapid elongation and primary wall synthesis (7-14 days postanthesis), incorporation of radioactivity from GDP-(14)C-glucose into hot alkali-insoluble product is high. This activity gradually declines and is not demonstrated in older fibers undergoing active deposition of secondary wall. With respect to all characteristics examined, the product from GDP-glucose resembles cellulose. Incorporation of UDP-(14)C-glucose into hot alkali-insoluble product was low in young fibers but increased to high levels in older fibers. This product was shown to be soluble in chloroform-methanol, and when chromatographed in lipid solvents it was separated into three components. Activity for the production of two of these three presumed glucolipids increased with increasing age of fibers.
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Affiliation(s)
- D P Delmer
- Department of Biology, University of California, San Diego, La Jolla, California 92037
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