Export 798 results:
Sort by: Author Title Type [ Year  (Desc)]
1998
Valentine, AM, P. Tavares, AS Pereira, R. Davydov, C. Krebs, BM Koffman, DE Edmondson, BH HUYNH, and SJ Lippard. "{Generation of a mixed-valent Fe(III)Fe(IV) form of intermediate Q in the reaction cycle of soluble methane monooxygenase, an analog of intermediate X in ribonucleotide reductase R2 assembly}." Journal Of The American Chemical Society. 120 (1998): 2190-2191.
Pereira, AS, W. Small, C. Krebs, P. Tavares, DE Edmondson, E. C. Theil, and BH HUYNH. "Direct spectroscopic and kinetic evidence for the involvement of a peroxodiferric intermediate during the ferroxidase reaction in fast ferritin mineralization." Biochemistry. 37 (1998): 9871-9876. AbstractWebsite

Rapid freeze-quench (RFQ) Mossbauer and stopped-flow absorption spectroscopy were used to monitor the ferritin ferroxidase reaction using recombinant (apo) frog M ferritin; the initial transient ferric species could be trapped by the RFQ method using low iron loading (36 Fe2+/ferritin molecule). Biphasic kinetics of ferroxidation were observed and measured directly by the Mossbauer method; a majority (85%) of the ferrous ions was oxidized at a fast rate of similar to 80 s(-1) and the remainder at a much slower rate of similar to 1.7 s(-1). In parallel with the fast phase oxidation of the Fe2+ ions, a single transient iron species is formed which exhibits magnetic properties (diamagnetic ground state) and Mossbauer parameters (Delta E-Q = 1.08 +/- 0.03 mm/s and delta = 0.62 +/- 0.02 mm/s) indicative of an antiferromagnetically coupled peroxodiferric complex. The formation and decay rates of this transient diiron species measured by the RFQ Mossbauer method match those of a transient blue species (lambda(max) = 650 nm) determined by the stopped-flow absorbance measurement. Thus, the transient colored species is assigned to the same peroxodiferric intermediate. Similar transient colored species have been detected by other investigators in several other fast ferritins (H and M subunit types), such as the human H ferritin and the Escherichia coli ferritin, suggesting a similar mechanism for the ferritin ferroxidase step in all fast ferritins. Peroxodiferric complexes are also formed as early intermediates in the reaction of O-2 With the catalytic diiron centers in the hydroxylase component of soluble methane monooxygenase (MMOH) and in the D84E mutant of the R2 subunit of E. coli ribonucleotide reductase. The proposal that a single protein site, with a structure homologous to the diiron centers in MMOH and R2, is involved in the ferritin ferroxidation step is confirmed by the observed kinetics, spectroscopic properties, and purity of the initial peroxodiferric species formed in the frog M ferritin.

Valentine, AM, P. Tavares, AS Pereira, R. Davydov, C. Krebs, BM Koffman, DE Edmondson, BH HUYNH, and SJ Lippard. "Generation of a mixed-valent Fe(III)Fe(IV) form of intermediate Q in the reaction cycle of soluble methane monooxygenase, an analog of intermediate X in ribonucleotide reductase R2 assembly." Journal of the American Chemical Society. 120 (1998): 2190-2191. AbstractWebsite
n/a
Gorokhovatsky, Y., D. Temnov, J. N. Marat-Mendes, CJM Dias, and D. K. Das-Gupta. "On the nature of thermally stimulated discharge current spectra in polyethylene terephthalate." Journal of Applied Physics. 83 (1998): 5337-5341. Abstract
n/a
Goulão, Miguel, António Silva Monteiro, José Furtado Martins, Fernando Brito Abreu, Alberto Bigotte Almeida, and Pedro Sousa. "A Software Evolution Experiment." European Software Control and Metrics Conference (ESCOM'98). Eds. Rob Kusters, Adrian Cowderoy, Fred Heemstra, and Jos Trienekens. Rome, Italy: Shakter Publishing B. V., 1998. Abstract
n/a
Tavares, P., AS Pereira, C. Krebs, N. Ravi, JJG Moura, I. Moura, and BH HUYNH. "Spectroscopic characterization of a novel tetranuclear Fe cluster in an iron-sulfur protein isolated from Desulfovibrio desulfuricans." Biochemistry. 37 (1998): 2830-2842. AbstractWebsite

Mossbauer and EPR spectroscopies were used to characterize the Fe clusters in an Fe-S protein isolated from Desulfovibrio desulfuricans (ATCC 27774). This protein was previously thought to contain hexanuclear Fe clusters, but a recent X-ray crystallographic measurement on a similar protein isolated from Desulfovibrio vulgaris showed that the protein contains two tetranuclear clusters, a cubane-type [4Fe-4S] cluster and a mixed-ligand cluster of novel structure [Lindley et al. (1997) Abstract, Chemistry of Metals in Biological Systems, European Research Conference, Tomar, Portugal]. Three protein samples poised at different redox potentials (as-purified, 40 and 320 mV) were investigated. In all three samples, the [4Fe-4S] cluster was found to be present in the diamagnetic 2+ oxidation state and exhibited typical Mossbauer spectra. The novel-structure cluster was found to be redox active. In the 320-mV and as-purified samples, the cluster is at a redox equilibrium between its fully oxidized and one-electron reduced states. In the 40-mV sample, the cluster is in a two-electron reduced state. Distinct spectral components associated with the four Fe sites of cluster 2 in the three oxidation states were identified. The spectroscopic parameters obtained for the Fe sites reflect different ligand environments, making it possible to assign the spectral components to individual Fe sites. In the fully oxidized state, all four iron ions are high-spin ferric and antiferromagnetically coupled to form a diamagnetic S = 0 state. In the one-electron and two-electron reduced states, the reducing electrons were found to localize, consecutively, onto two Fe sites that are rich in oxygen/nitrogen ligands. Based on the X-ray structure and the Mossbauer parameters, attempts could be made to identify the reduced Fe sites. For the two-electron reduced cluster, EPR and Mossbauer data indicate that the cluster is paramagnetic with a nonzero interger spin. For the one-electron reduced cluster, the data suggest a half-integer spin of 9/2 Characteristic fine and hyperfine parameters for all four Fe sites were obtained. Structural implications and the nature of the spin-coupling interactions are discussed.

Mateus, O., P. Taquet, MT Antunes, H. Mateus, and V. Ribeiro. "Theropod dinosaur nest from Lourinhã, Portugal." Journal of Vertebrate Paleontology. Vol. 18. 1998. 61. Abstract
n/a
Mateus, I., H. Mateus, MT Antunes, O. Mateus, P. Taquet, V. Ribeiro, and G. Manuppella. "Upper Jurassic Theropod Dinosaur embryos from Lourinhã (Portugal)." Upper Jurassic paleoenvironments in Portugal, Mem. Acad. Ciências de Lisboa. 37 (1998): 101-109. Abstract
n/a
Pereira, A., W. Small, C. Krebs, P. Tavares, D. Edmondson, E. Theil, and B. Huynh. "{Direct spectroscopic and kinetic evidence for the involvement of a peroxodiferric intermediate during the ferroxidase reaction in fast ferritin mineralization}." Biochemistry. 37 (1998): 9871-9876. Abstract
Rapid freeze-quench (RFQ) Mossbauer and stopped-flow absorption spectroscopy were used to monitor the ferritin ferroxidase reaction using recombinant (apo) frog M ferritin; the initial transient ferric species could be trapped by the RFQ method using low iron loading (36 Fe2+/ferritin molecule). Biphasic kinetics of ferroxidation were observed and measured directly by the Mossbauer method; a majority (85%) of the ferrous ions was oxidized at a fast rate of similar to 80 s(-1) and the remainder at a much slower rate of similar to 1.7 s(-1). In parallel with the fast phase oxidation of the Fe2+ ions, a single transient iron species is formed which exhibits magnetic properties (diamagnetic ground state) and Mossbauer parameters (Delta E-Q = 1.08 +/- 0.03 mm/s and delta = 0.62 +/- 0.02 mm/s) indicative of an antiferromagnetically coupled peroxodiferric complex. The formation and decay rates of this transient diiron species measured by the RFQ Mossbauer method match those of a transient blue species (lambda(max) = 650 nm) determined by the stopped-flow absorbance measurement. Thus, the transient colored species is assigned to the same peroxodiferric intermediate. Similar transient colored species have been detected by other investigators in several other fast ferritins (H and M subunit types), such as the human H ferritin and the Escherichia coli ferritin, suggesting a similar mechanism for the ferritin ferroxidase step in all fast ferritins. Peroxodiferric complexes are also formed as early intermediates in the reaction of O-2 With the catalytic diiron centers in the hydroxylase component of soluble methane monooxygenase (MMOH) and in the D84E mutant of the R2 subunit of E. coli ribonucleotide reductase. The proposal that a single protein site, with a structure homologous to the diiron centers in MMOH and R2, is involved in the ferritin ferroxidation step is confirmed by the observed kinetics, spectroscopic properties, and purity of the initial peroxodiferric species formed in the frog M ferritin.
Tavares, P., AS Pereira, C. Krebs, N. Ravi, JJG Moura, I. Moura, and BH HUYNH. "{Spectroscopic characterization of a novel tetranuclear Fe cluster in an iron-sulfur protein isolated from Desulfovibrio desulfuricans}." Biochemistry. 37 (1998): 2830-2842. Abstract
Mossbauer and EPR spectroscopies were used to characterize the Fe clusters in an Fe-S protein isolated from Desulfovibrio desulfuricans (ATCC 27774). This protein was previously thought to contain hexanuclear Fe clusters, but a recent X-ray crystallographic measurement on a similar protein isolated from Desulfovibrio vulgaris showed that the protein contains two tetranuclear clusters, a cubane-type [4Fe-4S] cluster and a mixed-ligand cluster of novel structure [Lindley et al. (1997) Abstract, Chemistry of Metals in Biological Systems, European Research Conference, Tomar, Portugal]. Three protein samples poised at different redox potentials (as-purified, 40 and 320 mV) were investigated. In all three samples, the [4Fe-4S] cluster was found to be present in the diamagnetic 2+ oxidation state and exhibited typical Mossbauer spectra. The novel-structure cluster was found to be redox active. In the 320-mV and as-purified samples, the cluster is at a redox equilibrium between its fully oxidized and one-electron reduced states. In the 40-mV sample, the cluster is in a two-electron reduced state. Distinct spectral components associated with the four Fe sites of cluster 2 in the three oxidation states were identified. The spectroscopic parameters obtained for the Fe sites reflect different ligand environments, making it possible to assign the spectral components to individual Fe sites. In the fully oxidized state, all four iron ions are high-spin ferric and antiferromagnetically coupled to form a diamagnetic S = 0 state. In the one-electron and two-electron reduced states, the reducing electrons were found to localize, consecutively, onto two Fe sites that are rich in oxygen/nitrogen ligands. Based on the X-ray structure and the Mossbauer parameters, attempts could be made to identify the reduced Fe sites. For the two-electron reduced cluster, EPR and Mossbauer data indicate that the cluster is paramagnetic with a nonzero interger spin. For the one-electron reduced cluster, the data suggest a half-integer spin of 9/2 Characteristic fine and hyperfine parameters for all four Fe sites were obtained. Structural implications and the nature of the spin-coupling interactions are discussed.
1997
Pereira, A., P. Tavares, S. Lloyd, D. Danger, D. Edmondson, E. Theil, and B. Huynh. "{Rapid and parallel formation of Fe3+ multimers, including a trimer, during H-type subunit ferritin mineralization}." Biochemistry. 36 (1997): 7917-7927. Abstract
Conversion of Fe ions in solution to the solid phase in ferritin concentrates iron required for cell function. The rate of the Fe phase transition in ferritin is tissue specific and reflects the differential expression of two classes of ferritin subunits (H and L). Early stages of mineralization were probed by rapid freeze-quench Mossbauer, at strong fields (up to 8 T), and EPR spectroscopy in an H-type subunit, recombinant frog ferritin; small numbers of Fe (36 moles/mol of protein) were used to increase Fe3+ in mineral precursor forms, At 25 ms, four Fe3+-oxy species (three Fe dimers and one Fe trimer) were identified, These Fe3+-oxy species were found to form at similar rates and decay subsequently to a distinctive superparamagentic species designated the ''young core.'' The rate of oxidation of Fe2+ (1026 s(-1)) corresponded well to the formation constant for the Fe3+- tyrosinate complex (920 s(-1)) observed previously [Waldo, G. S., {&} Theil, E. C. (1993) Biochemistry 32, 13261] and, coupled with EPR data, indicates that several or possibly all of the Fe3+-oxy species involve tyrosine. The results, combined with previous Mossbauer studies of Y30F human H-type ferritin which showed decreases in several Fe3+ intermediates and stabilization of Fe2+ [Bauminger, E. R., et al. (1993) Biochem, J. 296, 709], emphasize the involvement of tyrosyl residues in the mineralization of H-type ferritins. The subsequent decay of these multiple Fe3+-oxy species to the superparamagnetic mineral suggests that Fe3+ species in different environments may be translocated as intact units from the protein shell into the ferritin cavity where the conversion to a solid mineral occurs.
Mateus, I., H. Mateus, MT Antunes, O. Mateus, P. Taquet, V. Ribeiro, and G. Manuppella. "Couvée, oeufs et embryons d'un dinosaure théropode du Jurassique supérieur de Lourinhã (Portugal)." C.R Acad. Sci. Paris, Sciences de la terre et des planetes. 325 (1997): 71-78. Abstractmateus_et_al_1997_eggs_embryos_nest__couvee_oeufs_et_embryons_dun_dinosaure_theropode_du_jurassique_superieur_de_lourinha_portugal.pdfWebsite

Several well preserved clutches of dinosaurs have been discovered in the upper Kimmeridgian/ Tithonian of Lourinhã (Estramadur Province, Portugal). Some eggs of one clutch contained embryo elements of a theropod dinosaur. The egg-shell resembles that of eggs which have been discovered in the Upper Jurassic of Colorado

Mateus, Isabel, Horácio Mateus, Miguel Telles Antunes, Octávio Mateus, Philippe Taquet, Vasco Ribeiro, and Giuseppe Manuppella. "Couvée, øe}ufs et embryons d{\textquotesingle}un Dinosaure Théropode du Jurassique supérieur de Lourinha (Portugal)." Comptes Rendus de l{\textquotesingle}Académie des Sciences - Series {IIA} - Earth and Planetary Science. 325 (1997): 71-78. AbstractWebsite
n/a
Topič, M.a, Smole Furlan Fortunato Martins F. a J. a. "Analysis of front contact heterojunction in a-Si:H one-dimensional position sensitive detectors." Review of Scientific Instruments. 68 (1997): 1377-1381. AbstractWebsite

The influence of different transparent conducting oxides (TCO) on the transverse photoelectrical properties of one-dimensional position sensitive detectors based on p-i-n amorphous silicon structures was studied. For both SnO 2 and indium tin oxide, poor quality of the p layer was revealed by secondary ion mass spectroscopy measurements. Good agreement between experimental and simulation characteristics of TCO/p-i-n structure was additionally conditioned by a strong increase in defect states at the p layer surface which can be attributed to the reduction/ oxidation process at the TCO/p interface. However, the analysis showed that under reverse bias the spectral response of the p-i-n structure is not significantly affected by different TCO layers and conditions at the TCO/p heterojunction. Nevertheless, indium tin oxide is less appropriate for a front TCO layer due to the poor reverse dark current-voltage characteristic, i.e., higher leakage current component leading to lower signal to noise ratio. © 1997 American Institute of Physics.

Mateus, I., H. Mateus, MT Antunes, O. Mateus, P. Taquet, V. Ribeiro, and G. Manuppella. "Couvée, oeufs et embryons d'un dinosaure théropode du Jurassique supérieur de Lourinhã (Portugal)." Comptes Rendus de l'Académie des Sciences-Series IIA-Earth and Planetary Science. 325 (1997): 71-78. Abstract
n/a
Mateus, I., H. Mateus, MT Antunes, O. Mateus, P. Taquet, V. Ribeiro, and G. Manuppella. "Couvée, œufs et embryons d'un Dinosaure Théropode du Jurassique supérieur de Lourinhã (Portugal)." Comptes Rendus de l'Academie de Sciences - Serie IIa: Sciences de la Terre et des Planetes. 325 (1997): 71-78. Abstract
n/a
Romao, MJ, I. Kolln, JM Dias, AL Carvalho, A. Romero, P. F. Varela, L. Sanz, E. Topfer-Petersen, and JJ Calvete. "Crystal structure of acidic seminal fluid protein (aSFP) at 1.9 angstrom resolution: a bovine polypeptide of the spermadhesin family." Journal of Molecular Biology. 274 (1997): 650-660. Abstract

We report the three-dimensional crystal structure of acidic seminal fluid protein (aSFP), a 12.9 kDa poly-peptide of the spermadhesin family isolated from bovine seminal plasma, solved by the multiple isomorphous replacement method and refined with data to 1.9 Angstrom resolution with a final R-factor of 17.3%. aSFP is built by a single CUB domain architecture, a 100 to 110 amino-acid-residue extracellular module found in 16 functionally diverse proteins. The structure of aSFP reveals that the CUB domain displays a beta-sandwich topology organised into two 5-stranded beta-sheets, each of which contain two parallel and four antiparallel strands. The structure of aSFP is almost identical to that of porcine spermadhesins PSP-I and PSP-II, which in turn show limited structural similarity with jellyroll topologies of certain virus capsid proteins. Essentially, topologically conserved residues in these proteins are those internal amino acids forming the hydrophobic core of the CUB and the jellyroll domains, suggesting their importance in maintaining the integrity of these protein folds, On the other hand, the structure of aSFP shows structural features that are unique to this protein and which may provide a structural ground for understanding the distinct biological properties of different members of the spermadhesin protein family. (C) 1997 Academic Press Limited.

Romero, A., MJ Romao, P. F. Varela, I. Kolln, JM Dias, AL Carvalho, L. Sanz, E. TopferPetersen, and JJ Calvete. "The crystal structures of two spermadhesins reveal the CUB domain fold." Nature Structural Biology. 4 (1997): 783-788. Abstract

Spermadhesins, 12,000-14,000 M-r mammalian proteins, include lectins involved in sperm-egg binding and display a single CUB domain architecture. We report the crystal structures of porcine seminal plasma PSP-I/PSP-II, a heterodimer of two glycosylated spermadhesins. and bovine aSFP at 2.4 Angstrom and 1.9 Angstrom resolution respectively.

Dias, JM, AL Carvalho, I. Kolln, JJ Calvete, E. TopferPetersen, P. F. Varela, A. Romero, C. Urbanke, and MJ Romao. "Crystallization and preliminary x-ray diffraction studies of aSFP, a bovine seminal plasma protein with a single CUB domain architecture." Protein Science. 6 (1997): 725-727. Abstract

{Bovine acidic seminal fluid protein (aSFP) is a 12.9 kDa polypeptide of the spermadhesin family built by a single CUB domain architecture. The CUB domain is an extracellular module present in 16 functionally diverse proteins. To determine the three-dimensional structure of aSFP, the protein was crystallized at 21 degrees C by vapor diffusion in hanging drops, using ammonium sulfate, pH 4.7, and polyethyleneglycol 4000 as precipitants, containing 10% dioxane to avoid the formation of clustered crystals. Elongated prismatic crystals with maximal size of 0.6 x 0.3 x 0.2 mm(3) diffract to beyond 1.9 Angstrom resolution and belong to space group P2(1)2(1)2, with cell parameters a = 52.4 Angstrom

Tavares, P., AS Pereira, S. G. Lloyd, D. Danger, DE Edmondson, E. C. Theil, and BH HUYNH. "Mossbauer spectroscopic and kinetic characterization of ferric clusters formed in h-chain ferritin mineralization." Abstracts of Papers of the American Chemical Society. 213 (1997): 503-INOR. AbstractWebsite
n/a
Pereira, AS, P. Tavares, S. G. Lloyd, D. Danger, DE Edmondson, E. C. Theil, and BH HUYNH. "Rapid and parallel formation of Fe3+ multimers, including a trimer, during H-type subunit ferritin mineralization." Biochemistry. 36 (1997): 7917-7927. AbstractWebsite

Conversion of Fe ions in solution to the solid phase in ferritin concentrates iron required for cell function. The rate of the Fe phase transition in ferritin is tissue specific and reflects the differential expression of two classes of ferritin subunits (H and L). Early stages of mineralization were probed by rapid freeze-quench Mossbauer, at strong fields (up to 8 T), and EPR spectroscopy in an H-type subunit, recombinant frog ferritin; small numbers of Fe (36 moles/mol of protein) were used to increase Fe3+ in mineral precursor forms, At 25 ms, four Fe3+-oxy species (three Fe dimers and one Fe trimer) were identified, These Fe3+-oxy species were found to form at similar rates and decay subsequently to a distinctive superparamagentic species designated the ''young core.'' The rate of oxidation of Fe2+ (1026 s(-1)) corresponded well to the formation constant for the Fe3+- tyrosinate complex (920 s(-1)) observed previously [Waldo, G. S., & Theil, E. C. (1993) Biochemistry 32, 13261] and, coupled with EPR data, indicates that several or possibly all of the Fe3+-oxy species involve tyrosine. The results, combined with previous Mossbauer studies of Y30F human H-type ferritin which showed decreases in several Fe3+ intermediates and stabilization of Fe2+ [Bauminger, E. R., et al. (1993) Biochem, J. 296, 709], emphasize the involvement of tyrosyl residues in the mineralization of H-type ferritins. The subsequent decay of these multiple Fe3+-oxy species to the superparamagnetic mineral suggests that Fe3+ species in different environments may be translocated as intact units from the protein shell into the ferritin cavity where the conversion to a solid mineral occurs.

Matias, P., V. Fulop, A. Thompson, A. Gonzalez, and MA Carrondo. "{Desulfoferrodoxin structure determined by MAD phasing and refinement to 1.9-angstrom resolution reveals a unique combination of a tetrahedral FeS4 centre with a square pyramidal FeSN4 centre}." J Biol Inorg Chem. 2 (1997): 680-689. Abstract
The structure of desulfoferrodoxin (DFX), a protein containing two mononuclear non-heme iron centres, has been solved by the MAD method using phases determined at 2.8 Angstrom resolution. The iron atoms in the native protein were used as the anomalous scatterers. The model was built from an electron density map obtained after density modification and refined against data collected at 1.9 Angstrom. Desulfoferrodoxin is a homodimer which can be described in terms of two domains, each with two crystallographically equivalent non-heme mononuclear iron centres. Domain I is similar to desulforedoxin with distorted rubredoxin-type centres, and domain II has iron centres with square pyramidal coordination to four nitrogens from histidines as the equatorial ligands and one sulfur from a cysteine as the axial ligand. Domain I in DFX shows a remarkable structural fit with the DX homodimer. Furthermore, three beta-sheets extending from one monomer to another in DFX, two in domain I and one in domain II, strongly support the assumption of DFX as a functional dimer. A calcium ion, indispensable in the crystallisation process, was assumed at the dimer interface and appears to contribute to dimer stabilisation. The C-terminal domain in the monomer has a topology fold similar to that of fibronectin III.
1996
Devreese, B., P. Tavares, J. Lampreia, N. VanDamme, J. LeGall, JJG Moura, J. VanBeeumen, and I. Moura. "Primary structure of desulfoferrodoxin from Desulfovibrio desulfuricans ATCC 27774, a new class of non-heme iron proteins." FEBS LETTERS. 385 (1996): 138-142. Abstract
The primary structure of desulfoferrodoxin from Desulfovibrio desulfuricans ATCC 27774, a redox protein with two mononuclear iron sites, was determined by automatic Edman degradation and mass spectrometry of the composing peptides, It contains 125 amino acid residues of which five are cysteines, The first four, Cys-9, Cys-12, Cys-28 and Cys-29, are responsible for the binding of Center I which has a distorted tetrahedral sulfur coordination similar to that found in desulforedoxin from D. gigas, The remaining Cys-115 is proposed to be involved in the coordination of Center II, which is probably octahedrally coordinated with predominantly nitrogen/oxygen containing ligands as previously suggested by Mossbauer and Raman spectroscopy.
Coelho, A., P. Matias, M. Carrondo, P. Tavares, J. Moura, I. Moura, V. Fulop, J. Hajdu, and J. LeGall. "{Preliminary crystallographic analysis of the oxidized form of a two mono-nuclear iron centres protein from Desulfovibrio desulfuricans ATCC 27774}." Protein science : a publication of the Protein Society. 5 (1996): 1189-1191. Abstract
{Crystals of the fully oxidized form of desulfoferrodoxin were obtained by vapor diffusion from a solution containing 20% PEG 4000, 0.1 M HEPES buffer, pH 7.5, and 0.2 M CaCl2. Trigonal and/or rectangular prisms could be obtained, depending on the temperature used for the crystal growth. Trigonal prisms belong to the rhombohedral space group R32, with a = 112.5 A and c = 63.2 A; rectangular prisms belong to the monoclinic space group C2, with a = 77.7 A
Topic, M., Smole Furlan Fortunato Martins F. J. E. "Examination of 1-D position sensitive detector performance through analysis of front contact heterojunction." Materials Research Society Symposium - Proceedings. Vol. 420. 1996. 171-176. Abstract

The influence of different TCOs (SnO2 and ITO) on the photoelectrical properties of 1-D position sensitive detectors based on p-i-n structures was studied. A strong cross-contamination in the p-layer and contamination in the i-layer reduce the quality of the device. Numerical analysis of TCO/p-i-n structure also revealed a strong increase in defect states at the p-layer surface which can be attributed to the reduction of TCO. ITO seems to be less appropriate for a front TCO, although the spectral response of the p-i-n structure under reverse bias is not significantly affected by the conditions at the TCO/p heterojunction.