Pm In Length Research Articles

Effect of ultrafine-grained structure on kinetics and mechanism of VT6 titanium alloy fatigue failure

The kinetics and mechanism of fatigue fracture of VT6 titanium alloy (composition, wt.%: 5,95 V, 5,01 Al, 89,05 Ti) in the initial (hot-rolled) coarse-grained state and after equal channel angular pressing (ECAP) in the ultrafine-grained state were studied. Blanks used for ECAP were made of the specified alloy 20 mm in diameter and 100 mm in length previously subjected to homogenization annealing. Then, quenching was carried out in water from 960 °C (1 hour), tempering at 675 °C for 4 hours, ECAP at 650 °C ( Вс route, ф = 120°, n = 6 passes). The fine structure of the alloy after ECAP was studied using transmission electron microscopy at accelerating voltage 200 kV. The Time Group TH 300 hardness tester was used to determine alloy hardness. Static tension of round samples with a diameter of 5 mm was carried out on the Tinius Olsen H50KT universal test machine. Tension speed was 5 mm/min. Fatigue tests of 10 mm thick prismatic samples were carried out at 20 °C using the three-point bending test at the Instron 8802 unit. It was shown that under the same loading conditions, sample durability (the number of cycles before failure) from the alloy in the initial coarse-grained state is slightly higher than in the ultrafine-grained state. The number of cycles before fatigue crack formation, regardless of the alloy state, is at the level of 19—23 % of the total durability of samples. The straight section in kinetic diagrams of alloy fatigue fracture is approximated by the Paris equation. It was found that the rate of fatigue crack propagation in an alloy with an ultrafine-grained structure is somewhat higher than in an alloy with a coarse-grained structure. The microrelief of VT6 alloy fatigue fractures both in coarse-grained and ultrafine-grained state can be characterized as «scaly» with fatigue grooves on the surface of flakes. The region of fracture of the alloy with the ultrafine-grained structure contain a low-relief area 4—6 pm in length. The break, irrespective of the alloy state, has a pit microrelief.

Caracterização citogenética de Encyclia caximboensis (Orchidaceae) cultivadas in vitro

<em>E</em><em>ncyclia caximboensis</em><span> is an Amazonian species endemic to the Serra do Cachimbo, which is located between the northern of the Mato Grosso state and the southern part of Para state. Studies reporting in vitro cultivation and cytogenetic characterization of this species are still scarce. Therefore, the objective of this work was to determine the cytogenetic characteristics and to identify the nucleolar organizer regions (NORs) of the species </span><em>E. Caximboensis</em><span>, cultivated </span><em>in vitro.</em><span> Seeds of </span><em>E. caximboensis</em><span> were disinfected using a syringe and subsequently cultivated in MS medium without growth regulators. The germination started after 20 days of culture, with the development of protocorm and 40,500 seedlings were obtained after 90 days of culture. To perform the cytogenetic characterization, root tips of 180-day-old seedlings were submitted to blocking treatment using 3 µM trifiuralin and then fixed in methanol-acetic acid solution, 3:1 (v/v). The meristems were submitted to enzymatic digestion, fixed in methanol-acetic acid solution, 3:1 (v/v) and the slides were stained using 5% Giemsa solution. Ag-NOR banding was carried out on 20-day-old slides by incubation in 50% silver nitrate solution (AgNO3) for 19 hours. The results indicated that </span><em>E. caximboensis</em><span> has 2n=2x=24 with all metacentric type chromosomes, ranging from 1.88 to 0.66 pm in length, with simple NORs in small blocks localized in the proximal region of the third chromosome pair. </span>

Identification and Characterization of Gliocladium viride Isolated from Mushroom Fly Infested Oak Log Beds Used for Shiitake Cultivation

A green mold species that has not previously been reported in Korea was isolated from oak log beds used for shiitake (Lentinula edodes) cultivation that were infested by mushroom flies. In this study, we identify the mold species as Gliocladium viride (an anamorph of Hypocrea lutea) and describe its myeologieal properties. The fungus was cottony on both potato dextrose agar (PDA) and Czapek yeast extract agar (CYA), but was colored white on PDA and became yellowish green and brown on CYA. Mycelial growth on PDA attained a diameter of 73 mm at 30°C after 5 days. The fungus grew faster on malt extract agar (> 80 mm, 5 days at 25°C) compared to CYA and PDA (< 68 mm, 5 days at 25°C). Penieillate eonidiophores of the fungus are hyaline, smooth walled, branching above ty pically in four stages, and 120–240 pm in length. Club-shaped or slender phialides are formed on the metulae. Conidia of the fungus were ovate and elliptic, yellowish brown and green, and 2.5~3.0 μm × 1.8–2.3 μm in size. Typically, slimy conidia are formed in a mass and colored brown to dark green to almost black. The internal transcribed spacer rDNA and translation elongation factor 1 alpha gene sequences of the fungus isolated here show 99% identity with previously identified G viride strains.

A201 マイクロチャンネルを用いた赤血球変形挙動に関する生体外実験

In a human body, erythrocytes deform highly and can smoothly pass capillaries of which diameters are narrower than the cells'. Since capillaries connect all organs in a body, decrease in erythrocytes deformability causes several diseases. Therefore it is very important to evaluate the dynamic deformability of the erythrocyte at the microcirculation level. In this research, we produced a micro channel array with a 5pm×5pm square cross section of 100pm in length on the silicon substraight to simulate capillaries. After whole blood was centrifuged and erythrocytes were separated from plasma, the erythrocytes were diluted with autologous plasma by a hematocrit of 10%. This suspension was made to flow through the micro channels. Erythrocyte was observed using a high-speed video camera each day during preservation period. As a result, the time fluctuations of compressive strain of the RBCs agree with the theoretical curve of first-order lag element as a viscoelastic Kelvin model.

Greenockite and zincian greenockite in epithermal polymetallic AgAuTe mineralization, Tinos Island, Hellas: Description and conditions of formation

Greenockite-CdS and zincian greenockite-(Cdo.65Zjio.35)S were identified in low sulfidation epithermal Au-Ag-Te mineralization at Panormos Bay, Tinos Island, Hellas. Both minerals occur in stage VII of nine ore paragenetic stages as minute moderately reflective grains, up to 15 pm in length. The zincian greenockite displays a gray-bluish color, with a slight gray to gray-yellow anisotropy and yellowish to brownish-red internal reflections. It is intergrown with greenockite that coexists with stage VII - wurtzite, siderite, smithsonite and magnetite. Based on silicate, sulfide, and carbonate stabilities and fluid inclusion data, the approximate conditions of formation of stage VII and of zincian greenockite and greenockite are estimated to have been near 215 °C, at a hydrostatic pressure of 115 to 125 bars, / S2 = 10~141 to KΓ14'5, / 0 2 = KΓ44'2 to KT44 6, pH = 6.1 and aH2S(aq) = 10-3·6. For this temperature of formation and from previously published experimental data it is suggested that the Panormos Bay zincian greenockite has a wurtzite structure. The zinc and cadmium ion content of stage VII solutions is estimated as 0.09 and 0.34 ppm, at 115 and 125 bars respectively. It is suggested that substitution of cadmium by zinc is a rather complicated process depending on precipitation mechanism, pH, f 0 2, aH2S and possibly a c r of the fluid, associated with local mineral-fluid equilibrium.

Description and conditions of formation of new unnamed Ag-Cu and Ag-Cu-Au sulfotellurides in epithermal polymetallic Ag-Au-Te mineralization, Tinos Island, Hellas

Two new unnamed Ag-Cu ((Ag,Cu)12Te3S2) and Ag-A u-Cu ((Ag,Au, Cu)9Te2S3) or ((Ag,Cu)2|Au2Te§59) sulfotellurides were identified in low sulfidation epithermal Au-Ag-Te mineralization at Panormos Bay, Tinos Island, Greece. The sul­ fotellurides occur in stage V of nine paragenetic stages as minute, up to 13 pm in length, moderately reflective, white-gray isometric grains, with yellowish to brownish tint, depending on the gold and copper contents. The Ag-Cu sulfotelluride coexists with hessite and sylvanite in early stage V, whereas the Ag-Au-Cu sulfotelluride is in- tergrown with petzite and kostovite in late stage V. Both sulfotellurides also occur along the cleavages of hessite and petzite and replace stage II tetrahedrite. Based on silicate, sulfide, and telluride stabilities and fluid inclusion data, the con­ ditions of formation in stage V and the sulfotellurides formed between 230° to 260 °C at fS2 = 10~9 to 1095, f0 2 = 1035·86, fTe2 = 10-·92 to 10'938, pH = 5.74, aHTe (aq) = 2C)-io.88 and aH2Te(aqJ = 10 l20a, approximately. The gold and silver ion content in stage V solutions was 0.24 and 0.079 ppb, respectively.

Cytogenetic analysis of Arabidopsis.

AbstractThe cytogenetrcal analysis of a species enables the correlation of the structure, number and morphology of its chromosomes with heredity and variation. Most accessions of Arabidopszs thaliana L. have a diploid (2n) chromosome number of 10 (Fig. 1). The small genome size, convenient for many aspects of molecular genettcs, makes the chromosomes average only 1.5 pm in length (1,2) and intractable to analysts using many of the cytogenettc methods applied to other genera. However, despite the small size of chromosomes, the rapid advances in chromosome preparation methods, fluorescent microscopy, and staining since 1990 mean that analysis IS now straightforward (see refs.3–5). KeywordsChromosome NumberCover SlipChromosome PreparationPrint ExposureEnzyme BufferThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Sphaerospora ovophila N. Sp. and Myxobolus algonquinensis N. Sp. (Myxozoa, Myxosporea), Ovarian Parasites of Fish from Algonquin Park, Ontario, Canada

ABSTRACT. Sphaerospora ovophila n. sp. and Myxobolus algonquinensis n. sp., found in the ovary of the pumpkinseed (Lepomis gibbosus) and the golden shiner (Noremigonus crysoleucas) respectively from Algonquin Park, Ontario, are described using light and electron microscopy. Ovoid cysts of S. ovophila measured up to 500 pm in length. Monosporic pseudoplasmodia were ovoid or ellipsoid in shape and measured up to 12.5 pm in length. Spores were 7.2–8.4 pm long × 6.0–7.0 pm wide (in sutural plane) × 7.4–8.2 pm thick (perpendicular to sutural plane), with two subspherical polar capsules of equal size measuring 2.7–3.2 × 2.6–3.1 pm and each of which contained a polar filament with 6–7 coils. The spore had a straight sutural ridge which protruded slightly at the anterior end and contained two uninucleate sporoplasms. The spore valve had ornate folds on the posterior end. Cysts of M. algonquinensis ranged from ovoid to elongated ellipsoid in shape and measured up to 800 pm in length. Mature spores measured 13.G15.7 pm long × 10.1–12.1 pm wide × 5.0–6.9 pm thick. with two pyriform polar capsules of equal size measuring 5.1–5.5 pm × 2.5–2.9 pm, each of which contained a polar filament with 4–6 coils. The spores of M. algonquinensis had smooth valves, a straight sutural ridge and a distinct small intercapsular appendix.

The Blepharoplast of the Midstage Spermatid of Andreaeobryum macrosporum (Bryophyta: Andreaeopsida)

The blepharoplast of the midstage spermatid of Andreaeobryum macrosporum has a four-layered multilayered structure (MLS) and two superposed, slightly staggered, and overlapping basal bodies. The spline is composed of 30 parallel microtubules at its maximum width. Subtending the spline anteriorly, the lamellar strip (LS) is 1.83 pm long and 0.92 pm wide and has an elongated, wedge-shape with a pointed right anterior tip. Viewing the blepharoplast dorsally from anterior to posterior, the anterior basal body (ABB), approximately 0.95 pm in length, is situated over the right side of the MLS and is inserted at a level 0.42 pCm behind the spline's anterior apex. The posterior basal body (PBB), 2.75 pcm long, is positioned over the left side of the MLS and inserted 0.75 pm behind the spline's anterior apex. The ABB is essentially parallel with the spline microtubules over its entire length, while the anterior portion of the PBB curves outward gradually and becomes parallel with the spline in its posterior region. The combination of features that distinguish the midstage spermatid of Andreaeobryum from other mosses are its wide spline, wedge-shaped lamellar strip, comparatively short basal bodies, small length of stagger between basal bodies, and the PBB that curves gradually outward from its anterior tip. The data available for Andreaea suggest that its midstage spermatid resembles that of Andreaeobryum, although reconstructions and additional micrographic data are needed for both Andreaea and Takakia before generalizations for the class Andreaeopsida can be made. Andreaeobryum belongs to an unusual line of bryophyte evolution that also includes Andreaea and Takakia (Murray 1988; Renzaglia et al. 1991). While Andreaea is an old and well-established genus, Andreaeobryum is relatively new, having been described in 1976 by Steere and Murray (1976) and further defined by Murray (1988). Andreaea and Andreaeobryum have been grouped together in either the class Andreaeopsida (Crum & Anderson 1981; Murray 1988) or subclass Andreaeidae (Schofield 1985; Vitt 1984). According to Murray (1988), Andreaea and Andreaeobryum belong to separate orders, Andreaeales and Andreaeobryales, within the primitive class Andreaeopsida. The two genera are united by sporeling features and mode SAuthor for correspondence. e-mail: AnnRushing@ baylor.edu FIGUREs 1-6. Blepharoplast anatomy of Andreaeobryum macrosporum. -1-3. Tangential sections. -1. The spline anterior with its acutely curved left margin and closed aperture. Above, the extended triplet is part of the posterior basal body (cf. Fig. 18). -2. Slightly oblique section showing the left-marginal curvature of the subtending lamellar strip and the spline aperture (between arrows). -3. The spline aperture extends posteriorly beyond the lamellar strip where it closes by convergence of the microtubules on its right side with those on the left. -4. Near-median longitudinal section through the anterior basal body and the distal transition zone with its stellate pattern. The anterior mitochondrion is just becoming positioned beneath the lamellar strip. -5. Oblique-tangential section showing the full longitudinal extent of the anterior stellate pattern. -6. Oblique-tangential section section through the posterior basal body and the subtending spline and nucleus. Key to labeling: ABB, anterior basal body; AF, anterior flagellum; AM, anterior mitochondrion; ASP, anterior stellate pattern; EH, extended hub of basal body; ET, extended triplet; LS, lamellar strip; N, nucleus; PBB, posterior basal body; PSP, posterior stellate pattern; S, spline; S1-S4, specific strata of the multilayered structure; SA, spline aperture; bracket ([), lamellar strip. All micrographs are printed at a magnification of X67,500 except Fig. 6 where the magnification is X47,500. Except as otherwise noted for Figure 18, each scale bar represents

Formation of submicron colloidal particles from marine bacteria by viral infection

Formation of submicron colloidal particles from marine bacteria by viral infection

Ultrastructure of biflagellate spermatozoa in the freshwater clam,Corbicula leana(Prime)

Summary In contrast to “primitive” uniflagellate spermatozoa of marine and freshwater bivalves, spermatozoa of the freshwater clam, Corbicula leana (Prime) have two flagella. One flagellum (50 μm in length) originates from each of the two centrioles. The axoneme of both flagella exhibit the typical 9+2 pattern. On each side of the flagellum is a thin membranous wing which originates from the plasma membrane of the flagellum. The sperm head (17 pm in length) is elongated and tapers with a slight curve. The indistinct midpiece contains a minimum of five mitochondria and a set of centrioles. The mitochondria form a complex structure and envelop the posterior end of the nucleus like a calyx. The altered morphology of the spermatozoa from C. leana is discussed in relation to its specialized mode of reproduction, i.e., hermaphroditic with possible self-fertilization and brooding of young.

Development of techniques for the large-scale rearing of the larvae of the Australian freshwater fish golden perch, Macquaria ambigua (Richardson, 1845)

Experiments were conducted over four consecutive breeding seasons. Golden perch, Macquaria ambigua, larvae (total length, 5.0 mm) held at 23� to 25�C, commenced feeding on crustacean zooplankton (&lt;350 pm in length) five days after hatching, at age D6 (D1 = day of hatch). Zooplankton density had a significant effect (P &lt; 0.01) on the survival of larvae in 70-L aquaria. A delay of only two days to age D8 in initial feeding significantly reduced (P &lt; 0.01) survival, and larvae not offered zooplankton until D10 did not commence feeding. There was a positive linear relationship (r2 = 0.98) between survival in earthen ponds (0-57.6%) and the volume of small zooplankton sampled from the ponds at stocking, but survival was not affected by larval stocking density (32-365 m-2) or length of the culture period (28-53 days). A mean survival of 44.6% in ponds that were left dry over winter and then stocked 10-14 days after filling, was significantly higher (P &lt; 0.01) than survival in ponds stocked only 2-5 days after filling or in ponds inundated during winter. Survival, growth and production were not significantly different among ponds fertilized with inorganic fertilizer (NPK) alone or in combination with lucerne hay or poultry manure. Larvae grew at rates of 0.5-1.1 mm day-1, production rates were up to 153 kg ha-1 and a maximum number of 271 000 juveniles were reared in a 0.3 ha pond. Approximately 3 × 106 golden perch are produced annually at hatcheries in eastern Australia using techniques developed during this study.

A case report of an overseas-traveler's diarrhea probably caused by Chilomastix mesnili infection.

Many active flagellates were detected in stool samples of a 22-year-old Japanese male who traveled China and India. Microscopic observation showed that the organisms stained with Wright's solution were pyriform or rounded in shape, measuring 11.7-17.5 pm in length and 7.9-f2.2 pm in width. The posterior end was pointed. Three free anterior flagella were located in the front end. A spherical nucleus was situated near the anterior pole. Based on these morphological features we identified the organisms as trophozoites of Chilomastix mesnili, a common intestinal protozoon. Although we examined viral, bacterial and parasitic infections other than C.mesnili, no pathogen was found. From these results obtained, it was considered to be highly probable that C. mesnili infection was the cause of the diarrhea.

Weak Interactions in Crystals: 4,4′‐Di(tert‐butyl)‐N‐N′‐bipyridinium Diperchlorate—A Biphenyl Analogue with Perpendicular Pyridine Rings

AbstractOxidation of substituted N‐aminopyridinium compounds yields bipyridinium salts. After anion exchange Br− → CIO, it was possible to grow single crystals from the 4,4′‐di(tert‐butyl) derivative. The structure determined at 100 K shows a dihedral angle of 84° between the molecular halves connected by a shortened NN bond of 143 pm in length. This result is contrary to that expected from the isoelectronic correspondence 〉CC〈↔〉NN〈, which would suggest planarity, as has been observed experimentally both in solid biphenyl, and in tetraalkylhydrazine dications and radical cations. Lattice packing analysis, however, reveals the presence of hydrogen bonds C(H)…O between the phenyl rings and the perchlorate anions. AM 1 enthalpy hypersurface calculations for the isoelectronic series H5C5X–YC5H5 (X–Y = CC, +NC, +NN+, −BN+, BC, and BB−) predict single‐minimum potentials for both the dication 〉NN〈 as well as the dianion 〉BB〈 with the molecular halves twisted perpendicular to each other. In detailed model calculations, counteracting effects of π electron density delocalization vs. H/H repulsion of the ortho ring hydrogens adjacent to the central bond seem to dictate the delicate balance of the biphenyl twisting. For further experimental confirmation, the structure of the isosteric molecule 4,4′‐di(tert‐butyl)biphenyl has been determined: in contrast to the unsubstituted π hydrocarbon with a latticeenforced dihedral angle of 0°, close to the calculated value, the two molecular halves are twisted by 40°—as in biphenyl in the gas phase.

Tetrakis(hypersilyl)dithallium(TlTl): A Divalent Thallium Compound

A TlTl bond 291.4 pm in length is the prominent structural feature of the thallium(II) compound 1, the product of the reaction of RbSi(SiMe3)3 with TlN(SiMe3)2. The red compound 1, which is thermally unstable in solution, can be stored for longer periods in the solid state. equation image

Self Reversal of Chemical Remanent Magnetization On the Transformation of Maghemite to Haematite

SUMMARY Self-reversed chemical remanent magnetization (CRM) has been observed in haematite formed on heating maghemite which has been produced by the dehydration of acicular crystals of synthetic lepidocrocite, 1 to 2 pm in length. Our experimental evidence suggests that self reversal of haematite remanence only occurs when the parent maghemite is still blocked at the temperature of its transformation to haematite; when the transformation temperature is above the blocking temperature of the parent maghemite and it is unblocked, the resulting haematite remanence is normally magnetized. It is suggested that the strong dependence on remanent state supports exchange control of the self-reversal process. We propose that the self reversal is probably a general feature of the maghemite to haematite transition, and the significance of the source lepidocrocite in our experiments is that it produces maghemite of a suitable grain size so that much of it remains blocked at the elevated temperatures required to make the transformation to haematite occur over the short time scale of the laboratory experiments. In nature, transformation of maghemite to haematite will occur at much lower temperatures due to the much longer time scales involved, and self reversal of the resulting CRM may occur over a much less restricted grain size range of parent maghemite.

Polyploidy and body size variation in a natural population of the rotifer Euchlanis dilatata

Polyploidy has been reported in many plant species and in some animal species (reviewed by Lewis, 1980 and Suomalainen et al., 1987, respectively). A common consequence of polyploidy in plants is an increase in size (Lewis, 1980; Tal, 1980; Levin, 1983). In animals, most of the studies supporting this generalization are based on comparisons of body sizes of individuals from different populations. In this case, body size variation may reflect environmental differences to which populations of different ploidy are adapted. Very few comparisons of sympatric diploid and polyploid individuals are available either to support or counter this generalization. In Artemia parthenogenetica, pentaploids are larger than sympatric diploids (Wang, 1988). However. in the unisexual fish Poeciliopsis monachu-lucida triploids usually grow more slowly and have a smaller body size than sympatric diploids (Schultz, 1982). In rotifers, interpopulation variation in body size among geographically or temporally separated populations may have a genetic basis (King and Serra, 1980; Yufera, 1982; Serra and Miracle, 1983; She11 and Carrillo, 1984). Morales ( 1987) surveyed lakes in the Sierra Nevada, Spain, and found considerable body size variation in Euchlunis dilatata among the lakes. Morales-Baquero (1988) quantified this variation morphometrically for E. d&tutu from 70 populations. He reported body sizes ranging from 177 pm-340 pm in length and from 125 pm-270 pm in width. He concluded that interlake variation was a more important determinant of body size than intralake factors and hypothesized that these differences might have a genetic basis. The genetic basis underlying body size variation has not previously been investigated in any rotifer. One of us (EJW) noted substantial intrapopulational body size variation in E. dilatata collected from Devils Lake (Lincoln County, Oregon), with animals of two distinct body sizes found during 12 months of intensive sampling. Animals with the

Morphological evidence for a single bacterial etiology in Texas necotizing hepatcpanceatitis in Penaeus vannamei (Crustacea. Decapoda)

Morphological evidence for a single bacterial etiology in Texas necotizing hepatcpanceatitis in Penaeus vannamei (Crustacea. Decapoda)

Increased erythrocyte rigidity in chronic alcoholics without cirrhosis: Deformability improvement of erythrocyte sub-populations after alcohol withdrawal

Red blood cell (RBC) deformability in chronic alcoholism has been studied, using the Cell Transit Analyzer (CTA) which provides transit times of 5000 individual RBC passing via cylindrical micropores of 5.0 pm in diameter and 15 pm in length. Blood from chronic alcoholic patients without cirrhosis was studied before and after 8 days alcohol withdrawal. The results indicate: 1) the mean transit time of the RBC population from alcoholic patients is greater than those of the control population, 2) these changes affect the entire cell population and not only a sub-population, 3) alcohol withdrawal for 8 days improved the deformability of the most rigid cells of alcoholic patients (i.e., a slight but significant decrease of the highest percentile values of the transit time distribution).

The molecular structure of disilylacetylene, determined by electron diffraction in the gas phase

The molecular structure of disilylacetylene (1,4-disila-but-2-yne) in the gas phase has been determined from electron diffraction measurements. The refined structural parameters ( r α 0 basis) are, rCC 121.60(13) pm, rSi-C 180.77(8) pm, rSi-H 148.34(17) pm and ∠ HSiC 109.65(39)°. The conformation is found to be staggered. The Si··Si distance is found to be 1.61(32) pm more than calculated from the bond lengths after allowance for the linear shrinkage effect. The bond lengths are compared with those found in other silyl acetylenes and silyl cyanides; the SiC bond in the acetylenes ranges from 180.2 to 182.7 pm in length, whereas in the cyanides the SiC bond length is close to 185 pm.