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Jim Clark - One of the best experts on this subject based on the ideXlab platform.
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plasmodial incompatibility in the myxomycete Didymium squamulosum
Mycologia, 2003Co-Authors: Jim ClarkAbstract:A genetic analysis of plasmodial fusion in the CR 10 isolate of Didymium squamulosum indicated that this isolate was heterozygous for two fusion loci. These loci display dominant and recessive alleles, and any two plasmodia must be phenotypically identical for these loci before they will fuse.
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Didymium ovoideum culture and mating system
Mycologia, 1994Co-Authors: Jim Clark, Steven L StephensonAbstract:Reliable spore to spore culture of Didymium ovoideum was achieved using a high CaCl2 fruiting me? dium. Fourteen isolates from southwestern Virginia and northern West Virginia were investigated and all displayed a heterothallic mating system. Only two mat? ing types (A1 and A2) were uncovered, and in all 14 isolates the mating type segregation ratio was highly skewed with one of the mating types (usually A2) miss- ing or greatly reduced in frequency. No plasmodia were produced when clones of these mating types were crossed to all known Didymium iridis sibling species mating type testers. This suggests that D. ovoideum is a distinct biological species.
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Didymium iridis reproductive systems additions and meiotic drive
Mycologia, 1993Co-Authors: Jim Clark, John C LandoltAbstract:Three heterothallic Mexican isolates (Mex 1, Mex 2, and Mex 3) of Didymium iridis belong to the reproductively isolated A5 mating series of this morphospecies. This was unexpected in that the sole ...
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the myxamoebae of Didymium iridis and physarum polycephalum are immortal
Mycologia, 1992Co-Authors: Jim ClarkAbstract:(1992). The Myxamoebae of Didymium Iridis and Physarum Polycephalum are Immortal. Mycologia: Vol. 84, No. 1, pp. 116-118.
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Didymium iridis mating systems partial compatibility between mating series
Mycologia, 1991Co-Authors: Jim Clark, Oneil Ray Collins, Hsichang TangAbstract:GB 1, a new heterothallic Didymium iridis isolate from England, produces plasmodia when mated to some ofthe Central American series interbreeding mating types, most ofthe reproductively isolated Pan 4c clones, and all of the Appalachia series interbreeding mating types. While the hybrids with the Central America and Pan 4c clones usually produced many inviable spores with skewed mating-type segregation ratios, the Appalachian hybrids generally displayed good viability and normal ratios. Al? though most D. iridis heterothallic isolates have mating-type alleles which are compatible with only a single geographically restricted mating series, the GB 1 isolate is partially compatible with 3 separate series. An additional heterothallic isolate from Florida represents another mating-type series repro? ductively isolated from previously described series and from GB 1.
Arturo Estradatorres - One of the best experts on this subject based on the ideXlab platform.
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Didymium azorellae a new myxomycete from cushion plants of cold arid areas of south america
Mycologia, 2017Co-Authors: Diana Wrigley De Basanta, Arturo Estradatorres, Ivan Garciacunchillos, Asuncion Cano Echevarria, Carlos LadoAbstract:A new species of Didymium (Myxomycetes), D. azorellae, isolated from plant debris in a moist chamber, collected during studies of cold arid areas of Argentina and Peru, is described. It can be distinguished by its small size, the tightly packed layer of lime crystals on the peridium, the very scant, or absent, capillitium, and the unique spore ornamentation, especially by scanning electron microscopy. The species developed on dead leaves of cushion plants growing in the extremely harsh environments of the central Andean puna at almost 5000 m elevation and the Andino-Patagonian steppe. Morphology was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included here. In order to confirm the identity of the new species described in this paper, a molecular study was conducted based on partial sequences of both the 18S rRNA and the elongation factor 1-alpha gene. Phylogenetic analysis including two specimens from different countries of the newly described species, Didymium azorellae, strongly supports the grouping of these specimens as a separate clade from the rest of the analyzed species.
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Didymium xerophilum a new myxomycete from the tropical andes
Mycologia, 2015Co-Authors: Diana Wrigley De Basanta, Carlos Lado, Joaquina Maria Garciamartin, Arturo EstradatorresAbstract:A new species of Didymium (Myxomycetes), D. xerophilum, is described, and some details of its life cycle are provided. The new species was collected during studies of arid areas of Argentina and Peru. It can be distinguished by the persistent funnel-shaped invagination of the peridium, the top of which appears as a deep umbilicus in closed sporothecae, and the calcareous hypothallus shared among several sporocarps. This combination of characters, with a circumscissile dehiscence of the sporotheca and a cream stalk packed with rhombic lime crystals, is unknown in other described species. Morphology was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included here. Phylogenetic analysis with 18S rDNA sequences of different species of Didymium supports the distinct identity of this new species. Some collections of this myxomycete were made at up to 4600 m, an altitude almost unknown for this group of microorganisms.
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spore to spore culture of Didymium operculatum a new myxomycete from the atacama desert of chile
Mycologia, 2011Co-Authors: Wrigley D De Basanta, Carlos Lado, Arturo EstradatorresAbstract:A new species of Didymium (Myxomyce- tes), D. operculatum, is described in this paper, and details of its life cycle are provided. The new species was recorded during studies of the Atacama Desert in Chile. It has been collected directly in the field and isolated in moist chamber cultures prepared with material from an endemic cactus. The distinguishing characters of this species are its dehiscence by means of an apical operculum combined with a whitish calcareous stalk and the banded reticulate ornamen- tation of the spores. The morphology of this new myxomycete was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included in this paper. Some comments are made on the patterns of distribution of Didymium species in arid lands and adaptive charac- ters enabling this genus to colonize such extreme environments. It is proposed that a longer cycle and the ability to resort to resistant forms many times during their development reflect the response of these myxomycetes to the largely unfavorable condi- tions of their environment.
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morphology and life cycle of a new species of Didymium myxomycetes from arid areas of mexico
Mycologia, 2008Co-Authors: Wrigley D De Basanta, Carlos Lado, Arturo EstradatorresAbstract:A new species of myxomycete, Didymium umbilicatum, isolated from the bark of Agavaceae, is described from arid zones of Mexico. This species was obtained from moist chamber cultures of Yucca spp. bark, collected in four different years from two states (Puebla and Queretaro) in central Mexico and found in the field from Hidalgo, Oaxaca and Puebla on the dead remains of Agave sp. The new species has small, flat, white sporocarps or short plasmodiocarps, 0.2–1.3 mm diam, and 0.15–0.4 mm tall. They are sessile on a reduced base or have a short, calcareous pale stalk and warted spores, warts fused in an irregular subreticulum by SEM. It is the sixth species of Didymium recently described from arid areas. The stability of the taxonomic characters of the species was confirmed by spore-to-spore culture on agar. Life cycle events are described from germination to sporulation. The morphology of the myxomycete specimens was examined with scanning electron microscopy and light microscopy, and micrographs of relevant ...
H A Davies - One of the best experts on this subject based on the ideXlab platform.
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magnetic properties of nanocrystalline Didymium nd pr fe b alloys
Journal of Applied Physics, 1999Co-Authors: H A DaviesAbstract:The initial results of a systematic study of the effects of Nd:Pr ratio and Fe:Didymium (where Didymium is a mixture of Nd and Pr) ratio on the magnetic properties of nanocrystalline melt spun Didymium–Fe–B alloys are presented and discussed. The stoichiometric composition, corresponding to Didymium2Fe14B, with Nd:Pr ratios of 1:3, 1:1, and 3:1 and the alloy series Didymiumy Fe94−yB6, with y=8, 10, 12, and 14 at % were investigated. Enhancement of remanence and energy product was observed for all compositions studied, arising from intergrain exchange coupling between the RE2Fe14B crystallites (generally having a mean diameter ∼40 nm) and, for the off-stoichiometric alloys, also between the RE2Fe14B and α-Fe grains. An excellent combination of (BH)max(185 kJ m−3) and intrinsic coercivity (810 kA/m) was observed for the (Pr0.75Nd0.25)2Fe14B alloy.
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the magnetic properties of nanocrystalline melt spun iron Didymium boron alloys
Materials Letters, 1993Co-Authors: W P Sequeira, S J Dobson, R A Buckley, H A DaviesAbstract:Abstract The results of a systematic study of the effect of Nd: Pr ratio on the magnetic properties of melt spun Fe-Didymium-B alloys (where Didymium is a mixture of Nd and Pr) are presented. Evidence is shown in all the isotropic alloys studied of remanence, J r >0.5 J s due to the nanocrystalline structure resulting from the melt spinning process. Evidence is also shown of interaction between the Nd and Pr in the alloys leading to Curie temperatures higher than expected from measurements on the pure Nd and Pr alloys.
Gerda Rogl - One of the best experts on this subject based on the ideXlab platform.
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study of thermal and phase stability of Didymium and iron containing cosb3 based skutterudites
2018Co-Authors: Pavel Brož, P Rogl, Frantisek Zelenka, Jan Vřesťal, Jiři Bursik, Gerda RoglAbstract:Skuterudity na bazi CoSb3 obsahujici dopujici prvky jsou slibnými kandidaty pro termoelektricke aplikace. Přitomnost Nd a Pr (jejich směsi znama jako Didymium (DD)) nebo dalsich prvků jako Sr, Ba, Yb jako dopantů v skutteruditech vede k vysoce ucinným termoelektrickým materialům, ale těkave prvky (Sb, Sr, Yb atd.) se mohou v provoznich podminkach odpařovat, což vede ke změnam struktury a negativnimu ovlivněni termoelektrických vlastnosti. Pro ziskani informaci o tepelne a fazove stabilitě skuteruditů na bazi CoSb3, obsahujicich DD a Fe, byla provedena měřeni pomoci tepelne analýzy a Knudsenovy efuzni hmotnostni spektrometrie.
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thermoelectric properties of p type Didymium dd based skutterudites ddy fe1 xnix 4sb12 0 13 x 0 25 0 46 y 0 68
Journal of Alloys and Compounds, 2012Co-Authors: P Rogl, Gerda Rogl, A Grytsiv, E Bauer, M Zehetbauer, Matthias Falmbigl, Y GelbsteinAbstract:Abstract The thermoelectric properties of ball milled Didymium (DD) based skutterudites DD y (Fe 1− x Ni x ) 4 Sb 12 skutterudites were studied for 0.13 ⩽ x ⩽ 0.25 and 0.46 ⩽ y ⩽ 0.68 in the temperature range from 300 to 800 K and were compared with those of DD y (Fe 1− x Ni x ) 4 Sb 12 with x = 0 of a previous work as well as with their Co-substituted counterparts. Didymium was used as natural double filler (4.76 mass% Pr and 95.24 mass% Nd). The figures of merit ZT of p-type DD y (Fe 1− x Ni x ) 4 Sb 12 skutterudites reach ZT ⩾ 1 for the composition range 0.13 ⩽ x ⩽ 0.2 (for x = 0.15 ZT is almost 1.1), however, ZT values rapidly decrease for a higher nickel content. The thermoelectric efficiency with more than 12% is remarkable and similar to the values for DD y (Fe 1− x Co x ) 4 Sb 12 skutterudites.
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a new generation of p type Didymium skutterudites with high zt
Intermetallics, 2011Co-Authors: Gerda Rogl, P Rogl, A Grytsiv, E Bauer, M ZehetbauerAbstract:Abstract This work evaluates the influence of single, double and triple filling of Didymium, Ca and Ba in Fe 4 Sb 12 as well as in Fe 3 CoSb 12 on the thermoelectric performance. Various filling levels, as well as various preparation methods and nanostructuring were used to improve the thermoelectric performance. It is shown that samples prepared via ball milling have a higher ZT (ZT = 1.1) than their hand milled counterparts (ZT ≈ 0.8). Co/Fe-substituted samples have ZT > 1.2 i.e. 25% higher than samples without Co, an average ZT up to 0.93 and an efficiency up to 14% for the temperature gradient of 300–800 K. With this good thermoelectric performance in such a wide temperature range these materials are hitherto the best p-type skutterudites for thermoelectric devices.
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multifilled nanocrystalline p type Didymium skutterudites with zt 1 2
Intermetallics, 2010Co-Authors: Gerda Rogl, P Rogl, A Grytsiv, E Bauer, M Zehetbauer, Michael Kerber, S PucheggerAbstract:Abstract The influence of double, triple and multi-filling of Didymium, Ca, Ba, Sr and Yb in Fe 3 CoSb 12 on the thermoelectric performance was investigated. Ball-milling followed by hot pressing was used for sample preparation to gain dense and nanostructured samples. Almost all of the samples studied in this work have a ZT higher than 1, some even reach ZT > 1.2 at 700 K or at 800 K and an average ZT up to 1.0 in the temperature range from 300 K to 800 K. Thermal expansion, hardness and the elastic moduli were investigated exemplarily for two alloys with ZT > 1.2. With these results we can claim to have very promising p-type skutterudites for thermoelectric devices.
Carlos Lado - One of the best experts on this subject based on the ideXlab platform.
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Didymium azorellae a new myxomycete from cushion plants of cold arid areas of south america
Mycologia, 2017Co-Authors: Diana Wrigley De Basanta, Arturo Estradatorres, Ivan Garciacunchillos, Asuncion Cano Echevarria, Carlos LadoAbstract:A new species of Didymium (Myxomycetes), D. azorellae, isolated from plant debris in a moist chamber, collected during studies of cold arid areas of Argentina and Peru, is described. It can be distinguished by its small size, the tightly packed layer of lime crystals on the peridium, the very scant, or absent, capillitium, and the unique spore ornamentation, especially by scanning electron microscopy. The species developed on dead leaves of cushion plants growing in the extremely harsh environments of the central Andean puna at almost 5000 m elevation and the Andino-Patagonian steppe. Morphology was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included here. In order to confirm the identity of the new species described in this paper, a molecular study was conducted based on partial sequences of both the 18S rRNA and the elongation factor 1-alpha gene. Phylogenetic analysis including two specimens from different countries of the newly described species, Didymium azorellae, strongly supports the grouping of these specimens as a separate clade from the rest of the analyzed species.
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Didymium xerophilum a new myxomycete from the tropical andes
Mycologia, 2015Co-Authors: Diana Wrigley De Basanta, Carlos Lado, Joaquina Maria Garciamartin, Arturo EstradatorresAbstract:A new species of Didymium (Myxomycetes), D. xerophilum, is described, and some details of its life cycle are provided. The new species was collected during studies of arid areas of Argentina and Peru. It can be distinguished by the persistent funnel-shaped invagination of the peridium, the top of which appears as a deep umbilicus in closed sporothecae, and the calcareous hypothallus shared among several sporocarps. This combination of characters, with a circumscissile dehiscence of the sporotheca and a cream stalk packed with rhombic lime crystals, is unknown in other described species. Morphology was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included here. Phylogenetic analysis with 18S rDNA sequences of different species of Didymium supports the distinct identity of this new species. Some collections of this myxomycete were made at up to 4600 m, an altitude almost unknown for this group of microorganisms.
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spore to spore culture of Didymium operculatum a new myxomycete from the atacama desert of chile
Mycologia, 2011Co-Authors: Wrigley D De Basanta, Carlos Lado, Arturo EstradatorresAbstract:A new species of Didymium (Myxomyce- tes), D. operculatum, is described in this paper, and details of its life cycle are provided. The new species was recorded during studies of the Atacama Desert in Chile. It has been collected directly in the field and isolated in moist chamber cultures prepared with material from an endemic cactus. The distinguishing characters of this species are its dehiscence by means of an apical operculum combined with a whitish calcareous stalk and the banded reticulate ornamen- tation of the spores. The morphology of this new myxomycete was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included in this paper. Some comments are made on the patterns of distribution of Didymium species in arid lands and adaptive charac- ters enabling this genus to colonize such extreme environments. It is proposed that a longer cycle and the ability to resort to resistant forms many times during their development reflect the response of these myxomycetes to the largely unfavorable condi- tions of their environment.
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morphology and life cycle of a new species of Didymium myxomycetes from arid areas of mexico
Mycologia, 2008Co-Authors: Wrigley D De Basanta, Carlos Lado, Arturo EstradatorresAbstract:A new species of myxomycete, Didymium umbilicatum, isolated from the bark of Agavaceae, is described from arid zones of Mexico. This species was obtained from moist chamber cultures of Yucca spp. bark, collected in four different years from two states (Puebla and Queretaro) in central Mexico and found in the field from Hidalgo, Oaxaca and Puebla on the dead remains of Agave sp. The new species has small, flat, white sporocarps or short plasmodiocarps, 0.2–1.3 mm diam, and 0.15–0.4 mm tall. They are sessile on a reduced base or have a short, calcareous pale stalk and warted spores, warts fused in an irregular subreticulum by SEM. It is the sixth species of Didymium recently described from arid areas. The stability of the taxonomic characters of the species was confirmed by spore-to-spore culture on agar. Life cycle events are described from germination to sporulation. The morphology of the myxomycete specimens was examined with scanning electron microscopy and light microscopy, and micrographs of relevant ...
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description and culture of a new succulenticolous Didymium myxomycetes
Mycologia, 2007Co-Authors: Carlos Lado, J Mosquera, A Estradatorres, Esperanza Beltrantejera, Wrigley D De BasantaAbstract:A new succulenticolous Myxomycete species, Didymium wildpretii, found on decaying remains of various species of cacti, is described from two arid zones of the world. This species was collected from central Mexico, at the southern limit of the Chihuahuan Desert, and from the Canary Islands (Spain). The new species has small, pale yellow sporocarps, 0.1-0.7 mm high, that are sessile or have short, orange-yellow, calcareous stalks and small, uniformly warted spores. The stability of the taxonomic characters of the species was confirmed with both moist chamber cultures and spore-to-spore culture on agar. Life cycle events are described from germination to sporulation. Myxomycete specimens were examined with scanning electron microscopy and light microscopy, and micrographs of relevant morphological details are included.