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Abstract
A phytochemical study of Sideritis infernalis led to the isolation of the new nor-diterpene adejone (17-nor-7α,18-dihydroxy-ent-kaur-16-one). The biosynthesis of this compound implies the decarboxylation of an epoxy-acid as the last step. In addition, three diterpenes with an ent-kaurene skeleton, episideridiol, candicandiol 7α-monoacetate and candidiol 15α-monoacetate, have been isolated from S. candicans for the first time in nature.
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Affiliation(s)
- Braulio M. Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC,Avda. Astrofísico F. Sánchez 3, 38206-La Laguna, Tenerife, Canary Islands, Spain
| | - Carlo Bressa
- Instituto de Productos Naturales y Agrobiología, CSIC,Avda. Astrofísico F. Sánchez 3, 38206-La Laguna, Tenerife, Canary Islands, Spain
| | - Concepción Fernández
- Instituto de Productos Naturales y Agrobiología, CSIC,Avda. Astrofísico F. Sánchez 3, 38206-La Laguna, Tenerife, Canary Islands, Spain
| | - Pedro González
- Instituto de Bioorgánica “Antonio González”, Universidad de La Laguna, Tenerife, Spain
| | - Ricardo Guillermo
- Instituto de Bioorgánica “Antonio González”, Universidad de La Laguna, Tenerife, Spain
| | - Melchor G. Hernández
- Instituto de Productos Naturales y Agrobiología, CSIC,Avda. Astrofísico F. Sánchez 3, 38206-La Laguna, Tenerife, Canary Islands, Spain
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2
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Fraga BM, Guillermo R, Hernández MG, Chamy MC, Garbarino JA. The incubation of 13α,17-dihydroxystemodane with Cephalosporium aphidicola. Molecules 2012; 17:1744-50. [PMID: 22322449 PMCID: PMC6268689 DOI: 10.3390/molecules17021744] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/19/2012] [Accepted: 02/03/2012] [Indexed: 11/17/2022] Open
Abstract
The biotransformation of 13α,17-dihydroxystemodane (3) with the fungus Cephalosporium aphidicola afforded 13α,17,18-trihydroxystemodane (4), 3β,13α,17-tri-hydroxystemodane (5), 13α,17-dihydroxy-stemodan-18-oic acid (6), 3β,11β,13α,17-tetra-hydroxystemodane (7), 11β,13α,17,18-tetrahydroxystemodane (8) and 3β,13α,17,18-tetra-hydroxystemodane (9). The hydroxylation at C-18 of the substrate points to a biosynthetically-directed transformation, because aphidicolin (2) is hydroxylated at this carbon. However, the C-3(β) and C-11(β) hydroxylations seem to indicate a xenobiotic biotransformation.
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Affiliation(s)
- Braulio M Fraga
- Instituto de Productos Naturales y Agrobiología, C.S.I.C., Avda. Astrofísico F. Sánchez 3, La Laguna, Tenerife, Canary Islands, 38206, Spain.
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3
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Molero M, Segura I, Hernández MG, Izquierdo MAG, Anaya JJ. Ultrasonic wave propagation in cementitious materials: a multiphase approach of a self-consistent multiple scattering model. Ultrasonics 2011; 51:71-84. [PMID: 20619866 DOI: 10.1016/j.ultras.2010.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 06/02/2010] [Accepted: 06/04/2010] [Indexed: 05/29/2023]
Abstract
This paper examines ultrasonic wave propagation through strongly heterogeneous materials such as cementitious materials, and deals meanly with the formulation of a multiphase approach of a self-consistent multiple scattering model, the so-called dynamic generalized self-consistent model (DGSCM) proposed by Yang [J. Appl. Mech. 70(2003) 575-582]. This extended model can describe the influence of the size and volume fraction of aggregates on cementitious materials, as well as the interaction, contribution, and influence of entrapped air voids together with the aggregates on frequency-dependent parameters such as the phase velocity and the attenuation coefficient. To show the performance of this approach, theoretical predictions were compared with experimental ultrasonic measurements over a wide frequency range from several mortar specimens with different features in their microstructure properties and concentrations of aggregates up to 60%. The multiphase approaches of both the DGSCM and the Waterman-Truell model (WT) were also compared. The obtained results of the multiphase DGSCM were found to be significantly better than those obtained from the N-phase WT model for ultrasonic measurements from cementitious materials at high aggregate concentrations. The feasibility of material characterization using the multiphase approach of DGSCM was also discussed.
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Affiliation(s)
- M Molero
- CAEND - CSIC/UPM, 28500 Arganda del Rey, Madrid, Spain.
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4
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Molero M, Segura I, Aparicio S, Hernández MG, Izquierdo MAG. On the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials. Ultrasonics 2010; 50:824-828. [PMID: 20537363 DOI: 10.1016/j.ultras.2010.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 04/23/2010] [Indexed: 05/29/2023]
Abstract
This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials, such as cementitious materials. To improve the measurement of this parameter on this kind of materials, a linear swept-frequency signal is used to drive an emitter transducer to conduct a through-transmission inspection in immersion. To filter out undesirable frequency content, time-frequency filtering and detection process are performed. The use of this method has been compared with two excitation techniques, the broadband and the narrowband pulses. The results obtained using the swept-frequency excitation together with the time-frequency filtering, allows the determination of the attenuation curves with high accuracy over a wide frequency range without the need for complicated equipment, and improves the effective bandwidth by using a unique pair of transducers.
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Affiliation(s)
- M Molero
- CAEND--Consejo Superior de Investigaciones Cientificas/Polytechnic University of Madrid, Arganda del Rey, Madrid, Spain.
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Fraga BM, Hernández MG, Fernández C, Santana JMH. A chemotaxonomic study of nine Canarian Sideritis species. Phytochemistry 2009; 70:1038-1048. [PMID: 19535115 DOI: 10.1016/j.phytochem.2009.05.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 04/22/2009] [Accepted: 05/12/2009] [Indexed: 05/27/2023]
Abstract
Nine taxa of the Sideritis genus, Sideritis argosphacelus var. spicata, Sideritis candicans var. eriocephala,Sideritis discolor, Sideritis kuegleriana, Sideritis lotsyi, Sideritis lotsyi var. mascaensis, Sideritis marmorea, Sideritis soluta and Sideritis tenoi, which are endemic from the Canary Islands, have been chemically studied. The diterpene sicanatriol 7beta,18-diacetate was obtained from S. argosphacelus var. spicata, whilst a nor-diterpene, epiadejone, and the 3(2H)-benzofuranone solutin have been found in S. soluta. Another diterpene, sidendrodiol 18-monoacetate, has been isolated from S. argosphacelus var. spicata, for the first time as a natural product. Known sesquiterpenes, diterpenes, triterpenes, sterols, flavones, coumarins and other aromatic derivatives have also been isolated. These studies support the botanical division of the genus into two subgenera, Sideritis and Marrubiastrum, the three sections of the latter subgenus, Cretica, Empedocleopsis and Marrubiastrum, and the elevation of S. argosphacelus var. spicata, S. candicans var. eriocephala and S. lotsyi var. mascaensis to the rank of species.
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Affiliation(s)
- Braulio M Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC, La Laguna, 38206 Tenerife, Canary Islands, Spain.
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6
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Fraga BM, Guillermo R, Hernández MG, Chamy MC, Garbarino JA. Biotransformation of two ent-Pimara-9(11),15-diene derivatives by Gibberella fujikuroi. J Nat Prod 2009; 72:87-91. [PMID: 19128148 DOI: 10.1021/np800647v] [Citation(s) in RCA: 7] [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] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The incubation of 19-hydroxy-13-epi-ent-pimara-9(11),15-diene (4) with Gibberella fujikuroi gave 8 alpha,19-dihydroxy-9 alpha,11alpha-epoxy-13-epi-ent-pimara-15-ene (6), 7-oxo-11 alpha,19-dihydroxy-13-epi-ent-pimara-8(9),15-diene (7), 7-oxo-11beta,19-dihydroxy-13-epi-ent-pimara-8(9),15-diene (9), and 8 alpha,19-dihydroxy-9 alpha,11 alpha:15,16-diepoxy-13-epi-ent-pimarane (11), while the feeding of 13-epi-ent-pimara-9(11),15-diene-19-oic acid (5) with this fungus afforded 1-oxo-2 alpha,9 alpha-dihydroxy-13-epi-ent-pimara-11,15-dien-19-oic acid (13), 1-oxo-2 beta,9 alpha-dihydroxy-13-epi-ent-pimara-11,15-dien-19-oic acid (14), 13-epi-ent-pimara-9(11),15-dien-1,19-dioic acid 1,2-lactone (15), and 1-oxo-12 beta-hydroxy-13-epi-ent-pimara-9(11),15-dien-19-oic acid (16). In both biotransformations, the main reaction was the epoxidation of the 9(11)-double bond, followed by rearrangement to afford allylic alcohols. The formation of lactone 15 represents the first time that a Baeyer-Villiger oxidation has been observed in a microbiological transformation with this fungus.
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Affiliation(s)
- Braulio M Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC, P.O. Box 195, 38206-La Laguna, Tenerife, Canary Islands, Spain.
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7
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8
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9
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Izquierdo MAG, Hernández MG, Anaya JJ, Martinez O. Speckle reduction by energy time-frequency filtering. Ultrasonics 2004; 42:843-846. [PMID: 15047394 DOI: 10.1016/j.ultras.2004.01.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Structural noise is a very important limitation to the visibility of flaw echoes in ultrasonic testing and evaluation of highly scattering materials. In order to enhance the signal-to-noise ratio, different algorithms have been developed. One of these techniques is based on filtering the spectrum low band of the received echo to obtain a significant improvement of the defect visibility. Based on this idea, in this work a new time-frequency technique is presented. In this method, block-processing autoregressive techniques are used to estimate the instantaneous center frequency of the traveling wave. From this information, a time-frequency filter is designed tuned at half the estimated instantaneous center frequency. Experimental results and the comparison with the non-time-frequency filtering technique are also included, showing that the proposed method has an excellent performance on SNR enhancement.
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Affiliation(s)
- M A G Izquierdo
- Departamento de Señales, Sistemas y Radiocomunicaciones, ETSI Telecomunicación, UPM, Ciudad Universitaria s/n, Arganda del Rey, Madrid 28040, Spain.
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Hernández MG, Anaya JJ, Ullate LG, Ibañez A. Effect of the fluid in the inclusions of cement paste on the ultrasonic velocity. Ultrasonics 2004; 42:865-869. [PMID: 15047398 DOI: 10.1016/j.ultras.2004.01.066] [Citation(s) in RCA: 1] [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] [Indexed: 05/24/2023]
Abstract
The durability of cement composites significantly depends on the movement of the fluids into the material through the porous system. The aqueous phase contained in the pores can cause irreversible damage from the dimensional stability viewpoint. In this sense, methods for non-destructive characterization of both, the porous structure and water content should be investigated. In this work, the effect of the fluid in the inclusions of the cement paste on the ultrasonic velocity is studied. Firstly, a theoretical analysis based on the micromechanical model, considering the microstructural information of the matrix and the fluid filling the pores, is presented. Some experimental work is made later using cement paste samples, whose porous structure is maintained dry or saturate with water. In both cases, the ultrasonic velocity is measured and compared to the one predicted by the micromechanical model. Using this technique, the ultrasonic velocity can be predicted with errors below 2% in the cases of dry or water saturated cement paste.
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Affiliation(s)
- M G Hernández
- Instituto de Automática Industrial, (CSIC) La Poveda, 28500 Arganda del Rey, Madrid, Spain.
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11
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Fraga BM, Guillermo R, Hernández MG. The microbiological transformation of two 15beta-hydroxy-ent-kaurene diterpenes by Gibberella fujikuroi. J Nat Prod 2004; 67:64-69. [PMID: 14738388 DOI: 10.1021/np030363n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The incubation of 15beta-hydroxy-3-oxo-ent-kaur-16-ene (1) with the fungus Gibberella fujikuroi afforded 11beta-hydroxy-3,15-dioxo-ent-kaurane (6), 11beta,15beta-dihydroxy-3-oxo-ent-kaur-16-ene (8), 7beta,11beta,15beta-trihydroxy-3-oxo-ent-kaur-16-ene (9), 7alpha,11beta-dihydroxy-3,15-dioxo-ent-kaurane (7), and 7alpha,11beta,15beta-trihydroxy-3-oxo-ent-kaur-16-ene (10). The incubation of 15beta-hydroxy-ent-kaur-2,16-diene (3) with the same fungus yielded 7alpha,11beta-dihydroxy-15-oxo-ent-kaur-2-ene (12), 7alpha,11beta,15beta-trihydroxy-ent-kaur-2,16-diene (13), 7beta,15beta-dihydroxy-ent-kaur-2,16-dien-19,6-olide (14), 1beta,7beta,15beta-trihydroxy-ent-kaur-2,16-dien-19-oic acid (15), 7alpha,11beta,16alpha-trihydroxy-15-oxo-ent-kaur-2-ene (17), and 7alpha,15beta,17-trihydroxy-11beta,16beta-epoxy-ent-kaur-2-ene (19). These results indicated that a 3-oxo group in ent-kaur-16-ene derivatives inhibits the oxidation at C-19, typical of the biosynthetic pathway of gibberellins and kaurenolides, while a 2,3-double bond or a 15beta-OH does not. In both substrates a 15beta-alcohol directs hydroxylations at C-11(beta) and C-7(alpha), while in those with a 2,3-double bond the functionalization of C-1(beta) is favored.
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Affiliation(s)
- Braulio M Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC, Avenida Astrofísico F. Sánchez 3, 38206-La Laguna, Tenerife, Canary Islands, Spain.
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Fraga BM, Hernández MG, Artega JM, Suárez S. The microbiological transformation of the diterpenes dehydroabietanol and teideadiol by Mucor plumbeus. Phytochemistry 2003; 63:663-668. [PMID: 12842138 DOI: 10.1016/s0031-9422(03)00291-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The microbiological transformation of dehydroabietanol (18-hydroxy-dehydroabietane) by Mucor plumbeus led to 2alpha,18-dihydroxy-abieta-8,11,13,15-tetraene, 2alpha,15-dihydroxy-dehydroabietanol, 2alpha-hydroxy-15-methoxy-dehydroabietanol, 7beta-hydroxy-2-oxo-dehydroabietanol, 15-hydroxy-2-oxo-dehydroabietanol and 15,16-dihydroxy-2-oxo-dehydroabietanol, whilst that of teideadiol (1alpha,18-dihydroxy-dehydroabietane) gave 2alpha-hydroxy-teideadiol, 7alpha-hydroxy-teideadiol and 7beta-hydroxy-teideadiol. Thus, 2alpha- and 7beta-hydroxylation occur in both biotransformations and the 15-hydroxylation is inhibited in the biotransformation of teideadiol by the presence of a 1alpha-alcohol.
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Affiliation(s)
- Braulio M Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC, Avda. Astrofísico F. Sánchez 3, La Laguna, 38206-Tenerife, Canary Islands, Spain.
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Fraga BM, González P, Hernández MG, Chamy MC, Garbarino JA. Microbial transformation of 18-hydroxy-9,13-epi-ent-pimara-7,15-diene by Gibberella fujikuroi. J Nat Prod 2003; 66:392-397. [PMID: 12662098 DOI: 10.1021/np020457h] [Citation(s) in RCA: 7] [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] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The incubation of the diterpene 18-dihydroxy-9,13-epi-ent-pimara-7,15-diene (3) with the fungus Gibberella fujikuroi gave 14 metabolites, 4 and 6-18. The carbons functionalized were the C-20 methyl and all the secondaries, except C-12. The main reaction observed was the epoxidation of the 7,8-double bond, which rearranged to form 7-keto derivatives, such as 10-17, or the allylic alcohol 18. Compound 9 was the only one obtained in which the 7,8-double bond of the substrate remained unaltered. This work confirms that, in the feeding of this type of diterpene with this fungus, the oxidation at C-19, typical of the biosynthesis of gibberellins from ent-kaur-16-ene, is inhibited.
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Affiliation(s)
- Braulio M Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC, P.O. Box 195, 38206-La Laguna, Tenerife, Canary Islands, Spain.
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14
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Fraga BM, González P, Hernández MG, Suárez S. The biotransformation of the diterpene 2beta-hydroxy-ent-13-epi-manoyl oxide by Gibberella fujikuroi. Phytochemistry 2003; 62:67-70. [PMID: 12475620 DOI: 10.1016/s0031-9422(02)00436-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Incubation of the diterpene 2beta-hydroxy-ent-13-epi-manoyl oxide with Gibberella fujikuroi afforded in good yield 2beta,6beta-dihydroxy-ent-13-epi-manoyl oxide, 2beta,12beta-dihydroxy-ent-13-epi-manoyl oxide and 2beta,20-dihydroxy-ent-13-epi-manoyl oxide, confirming that although ent-13-epi-manoyl oxide is a final metabolite of a biosynthetic branch in this fungus, more polar derivatives of this compound can be transformed by this micro-organism.
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Affiliation(s)
- Braulio M Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC, P.O. Box 195, 38206-La Laguna, Tenerife, Canary Islands, Spain.
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15
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Abstract
In order to enhance the defect in relation to background noise of large grained materials different algorithms have been developed. Wiener filtering techniques have proved to be efficient for the SNR enhancement of ultrasonic signals coming from highly scattering materials. These processing algorithms are based on designing a filter that has large gain at frequencies where the SNR is high and low gain at frequencies where SNR is small. However, this technique does not consider two important ultrasonic effects: the finite-time duration of the flaw UT signal coming from a defect and the distortion of the frequency components of the traveling wave-front due to the dispersion. In this work, a time-frequency Wiener filter is proposed that takes into account these two characteristics. Experimental results are presented, showing that the proposed time-frequency algorithm has an excellent performance on SNR enhancement.
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Affiliation(s)
- M A G Izquierdo
- Departamento de Señales, Sistemas y Radiocomunicaciones, ETSI de Telecomunicación, UPM, Ciudad Universitaria, Madrid, Spain.
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16
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Hernández MG, Anaya JJ, Izquierdo MAG, Ullate LG. Application of micromechanics to the characterization of mortar by ultrasound. Ultrasonics 2002; 40:217-221. [PMID: 12159935 DOI: 10.1016/s0041-624x(02)00140-3] [Citation(s) in RCA: 2] [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] [Indexed: 05/23/2023]
Abstract
Mechanical properties of concrete and mortar structures can be estimated by ultrasonic non-destructive testing. When the ultrasonic velocity is known, there are standardized methods based on considering the concrete a homogeneous material. Cement composites, however, are heterogeneous and porous, and have a negative effect on the mechanical properties of structures. This work studies the impact of porosity on mechanical properties by considering concrete a multiphase material. A micromechanical model is applied in which the material is considered to consist of two phases: a solid matrix and pores. From this method, a set of expressions is obtained that relates the acoustic velocity and Young's modulus of mortar. Experimental work is based on non-destructive and destructive procedures over mortar samples whose porosity is varied. A comparison is drawn between micromechanical and standard methods, showing positive results for the method here proposed.
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Affiliation(s)
- M G Hernández
- Instituto de Automática Industrial, (CSIC) La Poveda, Madrid, Spain.
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17
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18
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Fraga BM, Hernández MG, González P, Chamy MC, Garbarino JA. The biotransformation of 18-hydroxy-9-epi-ent-pimara-7,15-diene by Gibberella fujikuroi. Phytochemistry 2000; 53:395-399. [PMID: 10703064 DOI: 10.1016/s0031-9422(99)00542-7] [Citation(s) in RCA: 7] [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] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Incubation of 18-hydroxy-9-epi-ent-pimara-7,15-diene with the fungus Gibberella fujikuroi gave the compounds 18-hydroxy-7 alpha,8 alpha-epoxy-9-epi-ent-pimara-15-ene, 18-hydroxy-7-oxo-ent-pimara-15-ene, 6 beta, 18-dihydroxy-7 alpha, 8 alpha-epoxy-9-epi-ent-pimara-15-ene, 9 beta,18-dihydroxy-7 alpha, 8 alpha-epoxy-ent-pimara-15-ene and 6 beta, 14 alpha, 18-trihydroxy-9-epi-ent-pimara-7,15-diene. Oxidation of C-19, which is characteristic of the biosynthesis pathway of the gibberellins is not produced.
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Affiliation(s)
- B M Fraga
- Instituto de Productos Naturales y Agrobiología, Tenerife, Canary Islands, Spain.
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19
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Fraga BM, González P, Hernández MG, Suárez S. Formation of 2,3-seco-acids in the biotransformation of the diterpene ribenone by Gibberella fujikuroi. Tetrahedron 1999. [DOI: 10.1016/s0040-4020(98)01190-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Fraga BM, González P, Guillermo R, Hernández MG. Microbiological transformation of manoyl oxide derivatives by Mucor plumbeus. J Nat Prod 1998; 61:1237-1241. [PMID: 9784159 DOI: 10.1021/np980133m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Biotransformations of jhanol (18-hydroxymanoyl oxide) (2), jhanidiol (1beta,18-dihydroxymanoyl oxide) (3), and 1-oxo-jhanol (1-oxo-18-hydroxymanoyl oxide) (4) by the fungus Mucor plumbeus have been studied. In the incubation of 2 there exists a preference for hydroxylation at C-2(alpha) (8) and C-6(beta) (9-11) and, to a lesser degree, at C-1(alpha) (7), C-11(alpha) (6), and C-11(beta) (5 and 10). In the second substrate (3), the presence of a 1beta-hydroxyl group inhibits 6beta- or 11-hydroxylation. Epoxidation of the vinyl group constitutes the main reaction, with the positions 2alpha (14) and 3beta (15) being hydroxylated. In the incubation of 4, there was a preference for 6beta-hydroxylation (21) or epoxidation of the vinyl group (22). Other hydroxylations observed were at the 2alpha (19), 2beta (20), 3alpha (23), 3beta (24), and 11beta (18) positions.
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Affiliation(s)
- B M Fraga
- Instituto de Productos Naturales y Agrobiología, CSIC, P.O. Box 195, La Laguna, 38206-Tenerife, Canary Islands, Spain. Laguna, Tenerife, Spain.
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21
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Fraga BM, González P, Guillermo R, Hernández MG. The biotransformation of manoyl oxide derivatives by Gibberella fujikuroi: The fungal epimerization of an alcohol group. Tetrahedron 1998. [DOI: 10.1016/s0040-4020(98)00308-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Fraga BM, González P, Guillermo R, Hernández MG, Perales A. The chemical and microbiological preparation of 15-oxo-gibberellin derivatives. Tetrahedron 1995. [DOI: 10.1016/0040-4020(95)00577-u] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Fraga BM, González P, Guillermo R, Hanson JR, Hernández MG, Takahashi JA. The microbiological transformation of two ent-16 beta,17-epoxykaurane derivatives by Gibberella fujikuroi. Phytochemistry 1994; 37:717-721. [PMID: 7765685 DOI: 10.1016/s0031-9422(00)90345-5] [Citation(s) in RCA: 8] [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] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The biotransformation of ent-16beta-17-epoxy-7 alpha-hydroxykaurane by Gibberella fujikuroi affords ent-7 alpha,11 alpha,16 beta,17-tetrahydroxykaurane and ent-7 alpha, 9 alpha, 16 beta, 17-tetrahydroxykaurane. These results indicated that the presence of the 16 alpha, 17-diol group, into which the 16 alpha, 17-epoxy is transformed in the medium, inhibits oxidation at C-19 and favours hydroxylation at C-11(beta). Incubation of ent-16 beta, 17-epoxykauran-19-oic acid, via the 16 alpha, 17-diol, gave the 7-aldehyde of 16 alpha, 17-dihydroxy-GA12.
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Affiliation(s)
- B M Fraga
- Instituto de Productos Naturales y Agrobiología, La Laguna, Canary Islands, Spain
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Fraga BM, Hanson JR, Hernández MG, Tellado FG. The first partial synthesis of 14-hydroxy-gibberellin esters. A titanium (IV)-amide catalysed rearrangement of epoxides. Tetrahedron Lett 1989. [DOI: 10.1016/s0040-4039(01)93383-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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