Penultimate Cell Research Articles

Preventing effect of different interstitial materials on thermal runaway propagation of large-format lithium iron phosphate battery module

Thermal runaway propagation (TRP) has become an urgent problem in the field of lithium-ion battery (LIB) fire safety, bringing potential risks to their large-scale applications. In this work, a novel strategy to prevent TRP of large-format lithium iron phosphate battery (LFP) module using aerogel, polyimide foam (PIF) and mica tape composite insulation cotton (MTCC) is proposed and investigated experimentally under two modules. One module consists of three batteries with insulation placed in every other battery (Individual Insulation Module, IIM), and the other module has four batteries with insulation placed in every third battery (Spacer Insulation Module, SIM). The prevention effect of the interstitial materials is analyzed by changing the thickness and configuration type in two modules. In addition, the heat transfer from the front batteries to the last battery under SIM is calculated. The results show that both the aerogel and 2 mm PIF can prevent TRP, and the latter can reduce the heat transfer power from the penultimate cell to the last cell from 785.28 W to 314.2 W. However, PIF and MTCC with 1 mm thickness can only prolong the TRP time by 1351 and 1462 s, respectively. Modules with SIM configuration are less dangerous than those with IIM. The heat from the penultimate battery dominates the temperature rise of the last battery, while the heat transferred from other parts to the last battery only accounts for 10–19 % of the total heat.

Rational configuration of finishing group and winding unit for a continuous broad-strip mill

7In hot rolling on a continuous broad-strip mill, the final structure and mechanical properties of the strip are mainly formed in the finishing group and the winding unit. A number of factors limit the development of new hot-rolling conditions for low-carbon steel strip on the basis of the austenite recrystallization diagram [1] and optimal metal structure [2]. The chosen conditions are often somewhat nonoptimal on account of the technological, energy, and configurational constraints of the mill. Thus, the equal intercell distances L int in the finishing group of the mill and the actual distance from the last cell of the finishing group to the first section of the sprayer unit L fg-su do not permit the required optimization. For example, for the 2000 mill at OAO NLMK, L int = 6 m and L fg-su = 28 m. Less severe reduction in the first cells of the finishing group (at high temperature and low speed of the strip) in optimizing thick-strip rolling only partially limits the collective growth of the austenite grains in the intervals between the cells, after the end of primary recrystallization. Increasing the reduction in the subsequent cells (at lower temperatures and higher rolling speeds) ensures complete primary recrystallization but there is an upper limit on the rolling force in the penultimate cell. Moreover, in establishing the relative reduction, its critical value must be taken into account ( e < e cr ). In the present work, we develop a rational configuration of the finishing group and winding system for a continuous broad-strip mill, by analysis of the conditions of structure formation in the rolled strip. The completeness of recrystallization of the austenitic structure in eU 3 OO low-carbon steel at the beginning of the next reduction in finishing-group cell ( i + 1) is described by the equation [1]

Ascomatal Morphogenesis in Myxotrichum arcticum Supports the Derivation of the Myxotrichaceae from a Discomycetous Ancestor

Electron microscopy shows that ascomata of Myxotricum arcticum bear a striking resemblance to discocarps in morphogenesis and in previously overlooked aspects of gross morphology. Although mature ascomata of M. arcticum superficially resemble reticuloperidial cleistothecia common in the Onygenales, the bramble-like aggregation of thick-walled hyphae, previously considered to represent a closed peridium, forms a basket-like apothecium that overarches a distinct hymenium of stipitate, protunicate asci interspersed with paraphyses. There is no evidence of asci developing in chains and at different levels as is characteristic of the centrum of many Eurotiomycetes. Instead, more or less globose, stipitate and evanescent asci arise individually from penultimate cells of croziers and develop almost synchronously across a distinct hymenial layer derived from a richly branched network of crozier-bearing hyphae. After dissolution of the ascus wall, ascospores adhere to a membranous sheath that underlies the hymenium. These observations provide strong support for prior suggestions based on molecular phylogenetic comparisons that the Myxotrichaceae recently are derived from a helotialean ancestor. Observations of conidiogenesis show that the typical Oidiodendron anamorph is accompanied by a second conidiogenous form with ampullae and botryose clusters of blastic conidia.

Ascomatal morphogenesis in Myxotrichum arcticum supports the derivation of the Myxotrichaceae from a discomycetous ancestor

Electron microscopy shows that ascomata of Myxotricum arcticum bear a striking resemblance to discocarps in morphogenesis and in previously overlooked aspects of gross morphology. Although mature ascomata of M. arcticum superficially resemble reticuloperidial cleistothecia common in the Onygenales, the bramble-like aggregation of thick-walled hyphae, previously considered to represent a closed peridium, forms a basket-like apothecium that overarches a distinct hymenium of stipitate, protunicate asci interspersed with paraphyses. There is no evidence of asci developing in chains and at different levels as is characteristic of the centrum of many Eurotiomycetes. Instead, more or less globose, stipitate and evanescent asci arise individually from penultimate cells of croziers and develop almost synchronously across a distinct hymenial layer derived from a richly branched network of crozier-bearing hyphae. After dissolution of the ascus wall, ascospores adhere to a membranous sheath that underlies the hymenium. These observations provide strong support for prior suggestions based on molecular phylogenetic comparisons that the Myxotrichaceae recently are derived from a helotialean ancestor. Observations of conidiogenesis show that the typical Oidiodendron anamorph is accompanied by a second conidiogenous form with ampullae and botryose clusters of blastic conidia.

The Drosophila Cyclin D-Cdk4 complex promotes cellular growth

Mammalian cyclin D-Cdk4 complexes have been characterized as growth factor-responsive cell cycle regulators. Their levels rise upon growth factor stimulation, and they can phosphorylate and thus neutralize Retinoblastoma (Rb) family proteins to promote an E2F-dependent transcriptional program and S-phase entry. Here we characterize the in vivo function of Drosophila Cyclin D (CycD). We find that Drosophila CycD-Cdk4 does not act as a direct G(1)/S-phase regulator, but instead promotes cellular growth (accumulation of mass). The cellular response to CycD-Cdk4-driven growth varied according to cell type. In undifferentiated proliferating wing imaginal cells, CycD-Cdk4 caused accelerated cell division (hyperplasia) without affecting cell cycle phasing or cell size. In endoreplicating salivary gland cells, CycD-Cdk4 caused excessive DNA replication and cell enlargement (hypertrophy). In differentiating eyes, CycD-Cdk4 caused cell enlargement (hypertrophy) in post-mitotic cells. Interaction tests with a Drosophila Rb homolog, RBF, indicate that CycD-Cdk4 can counteract the cell cycle suppressive effects of RBF, but that its growth promoting activity is mediated at least in part via other targets.

Identification of Rhizoctonia solani AG-UNK from Rice and Rice Fields in Texas as AG-11.

A survey of Texas rice fields in 1984 and 1985 yielded collections of Rhizoctonia solani AG-1 IA (causal agent of sheath blight of rice), R. oryzae (causal agent of sheath spot of rice), and a collection of eight multinucleate Rhizoctonia solani-like isolates that would interanastomose, but not anastomose, with tester isolates of AG-1 through AG-8 (representing those available at that time). In 1985, the isolates were characterized as R. solani AG-UNK (2). Isolates were recovered as atypical sclerotia from elutriated field soils in rice-soybean and rice-fallow rotations. Isolates also were recovered from late-season stem lesions nearly identical to those associated with sheath spot disease and from rice residues at locations throughout the upper Gulf Coast of Texas but at extremely low frequencies compared with recovery of R. solani AG-1 IA and R. oryzae. Teleomorphs of R. solani AG-UNK were observed during middle to late season on rice sheaths and matched descriptions of Thanatephorus cucumeris. Isolates were pathogenic on rice and soybean foliage in greenhouse trials but caused no significant yield losses when inoculated on adult rice plants (50 days after emergence) in field trials (2). Isolates exhibited mean hyphal diameters of 5.1 μm, averaged 8.3 nuclei per penultimate cell, grew 0.53 mm/h at 28°C on potato dextrose agar, and were negative in phenol tests (2). From samples maintained in storage during the past 15 years, the isolates have now been identified as AG-11 based on positive anastomosis with tester strains of AG-11 (1). This report records the occurrence of AG-11 in Texas, establishes the identity of the AG-UNK group, and expands the known geographic range of AG-11 in the United States.

Two Fluorescent Markers Identify the Vacuolar System of Schizophyllum commune

Vacuole-mediated proteolysis is important to sustained growth of filamentous wood-decaying fungi such as Schizophyllum commune. Demonstrating that specific proteases are vacuole associated has been difficult in these organisms due to the lack of specific markers for vacuolar compartments. We used 5-(and 6-)-carboxy-2′, 7′-dichlorofluorescein diacetate (carboxy-DCFDA) and a proprietary vacuolar membrane marker for yeast (MDY-64; Molecular Probes) for in situ fluorescent labeling of the vacuoles of S. commune mycelia grown on microscope slides. MDY-64 labels numerous small vesicles in S. commune mycelia in addition to larger vacuolar structures. In contrast, carboxy-DCFDA apparently is taken up by a subset of the MDY-64-labeled vesicles, accumulating primarily in larger vacuoles. Staining of mycelia with carboxy-DCFDA shows a transition from mostly cytoplasmic fluorescence in apical cells with little vacuolar fluorescence to nearly complete sequestration of the stain in vacuoles of older cells. In penultimate cells, both cytoplasm and vacuolar structures fluoresce. Vacuoles stained with carboxy-DCFDA typically were spherical and ranged in size from 0.4 μm to 3.2 μm in diameter with a mean of 1.8 um. Occasionally, in penultimate cells, tubular structures which stained with carboxy-DCFDA were found. ScPrB, a principal enzyme of nitrogen-limitation induced autolysis in S. commune, copurified in sucrose density gradients with carboxy-DCFDA and acid phosphatase, demonstrating its vacuolar localization.

Estimation of vacuolar pH in actively growing hyphae of the fungus Pisolithus tinctorius

The pH of vacuoles in tip cells of growing hyphae of a mycorrhizal fungus, Pisolithus tinctorius, was estimated by dual-wavelength microspectrofluorometry of 6-carboxyfluorescein. The vacuoles were found to have a modal pH of 7·0–7·5 and a pH range of 4·3–7·5. Vacuoles in penultimate cells tended to be more acid, with a modal group pH 5·5–6·0, although the range was similar at pH 4·8–7·2. The findings are discussed in relation to endocytosis and ageing of vacuoles in P. tinctorius.

Cell-to-cell transport via motile tubules in growing hyphae of a fungus

The system of pleiomorphic, motile tubules and vacuoles in growing hyphal tips of Pisolithus tinctorius has been shown to play a role in intracellular transport. Here we show that the same system also exchanges material between adjacent cells. This exchange is most obvious between terminal and penultimate cells following nuclear division in the tip cell and just before dissolution of the cell wall between the clamp connection and penultimate cell. At this stage the two new dolipore septa are complete. The process was studied in living hyphae using confocal and conventional fluorescence microscopy. Tubules could move in either direction across the septum and often extended and retracted several times and penetrated for some distance (e.g. 40 microns) into the receiving cell. Movements appeared co-ordinated and during the exchange tubules transiently interconnected vacuoles in adjacent cells and by peristaltic movements appeared to transfer material between them. The fluorescent tubules occupied a specific plane in the vicinity of the septum and remained in this plane for the duration of their movement, suggesting that their orientation and direction of movement is controlled. In freeze-substituted hyphae, tubular cisternae of similar dimensions to fluorescent tubules passed through the parenthesome pores perpendicular to the septum and in some cases entered the mouth of the septal pore. This indicates that the septal pore is of an appropriate dimension to accommodate the tubules and that they can cross the septal pore to exchange material between vacuole systems of adjacent cells. This is the first direct demonstration of such intercellular transport via a sub-cellular compartment.

Ion-exchange processes : A report on ION-EX 90, International Conference on Ion-Exchange Processes, held in Wrexham, U.K., 9–11 July, 1990.

881,887. Ion-exchange. NEW CONSOLIDATED GOLD FIELDS Ltd. Sept. 11, 1959 [Sept. 11, 1958], No. 31049/59. Class 46. An ion-exchange apparatus comprises a series of flat-bottomed square cells 4 which are interconnected by apertures 8 at low levels in the party walls 9 between them so that a pulp to be treated can flow through the series of cells. The final cell 414 has an outlet pipe 10 which, in the embodiment illustrated, is flexible, so that the outlet level may be adjusted. Ion-exchange resin in slurry form is fed on the surface of the penultimate cell 413 by means of a feed pipe 11. In operation pulp is fed in to the first cell 41 by inlet 7 and solids are kept in suspension by the gentle agitation of the paddle blades 5 and 6. To smooth the swirl to some extent, baffle plates 17 are provided on the sides of each cell 4. As soon as the pulp reaches a suitable operating level, which may be adjusted by adjusting the discharge level of the pipe 10, each cell excepting the last cell 414 is charged with a pre-determined quantity of ion exchange resin on its surface. A scoop operating mechanism is also started and fresh resin in slurry form is run in through the pipe 11 at a predetermined rate to replenish resin removed from the cell 413 by the scoop 13. The cell 414 is fitted with a scoop 13 which is designed to return entrained resin coming to the surface in the cell 414 to the circuit. The cell 414 thus acts as a trap. Portions of resin are regularly withdrawn from each cell and passed to the next cell and in the cell 41 passed to other circuits.

Mitosis and septum formation in the basidiomycete Helicobasidium mompa

Mitosis in clampless, dikaryotic hyphae of Helicobasidium mompa (Basidiomycota, Auriculariales sensu lato) was studied in apical and penultimate cells by correlating light microscopic and ultrastructural observations. Mitosis lasts about 10.5 min. In penultimate cells, mitosis occurs in the base of a branch whose initiation involves rupture of the wall. The extranuclear interphase spindle pole body contains two three-layered discs. Prophase is discerned by the polarization of the nucleus into a karyokinetic and a nucleolar region. During prometaphase, the spindle pole body discs move into the plane of the nuclear envelope where they occupy gaps. The spindle pole is enclosed by a cap of endoplasmic reticulum. At metaphase, nuclei lie side by side, the nucleolus resides in a nuclear evagination, and the spindle pole body discs are five layered. At anaphase, both chromatin to pole movement and extensive spindle elongation occur, astral microtubule populations reach a maximum, and multivesicular bodies aggregate at the spindle poles. Septa contain simple pores and form at the site previously occupied by the dividing nuclei. The results are compared with mitotic cycles in higher fungi and their evolutionary, phylogenetic, and functional significance is discussed.

Crozier Formation in Byssochlamys Nivea

Crozier formation in Byssochlamys nivea was studied by means of scanning electron microscopy (SEM) and light microscopic techniques. The continuous recording of crozier formation by time lapse cinematography combined with karyological analyses revealed an important deviation from the classical scheme of crozier formation. In B. nivea the divisions of the two nuclei during crozier formation are not simultaneous (conjugate). First, the nucleus in the crook region divides followed by septum formation, and then the nucleus in the basal region undergoes nuclear division followed by septum formation. The three-dimensional arrangement of crozier chains was analyzed by SEM. Subsequent croziers are turned against each other at an angle of 120?. There are two modes of crozier chain branching: formation of one crozier, each, from the penultimate cell and from the fused terminal cell, and simultaneous formation of the two croziers from the penultimate cell. Crozier formation is a prominent feature in the dikaryotic stage of the majority of higher Ascomycetes. The classical scheme is based on Claussen's observations of the development of Pyronema confluens Pers. ex Tul. and other Discomycetes (Claussen, 1912). Later work on other fungi, e.g., Saccobolus kerverni (Crouan) Boud. (Carroll, 1968), Pyronema domesticum (Sow. ex Gray) Sacc. (Hung and Wells, 1971) and Neurospora crassa Shear & Dodge (Raju, 1980) seemed to confirm the general validity of the pattern of crozier formation derived from studies of Pyronema confluens. In all cases, however, data were obtained from sections of fixed material since the croziers usually are hidden within the developing fruiting bodies. As a consequence, the time course and details of crozier formation had to be reconstructed from different croziers in various developmental stages. In all such investigations there was incomplete information as a result. In our paper, crozier formation is analyzed in a more primitive organism, Byssochlamys nivea Westling, than P. confluens and others. In this ascomycete, the croziers and, later on, the asci, are surrounded by very scanty, loose welts of hyphae. To suppress even this presumably primitive form of a peridium, a suitable nutrient medium which allowed normal ascus formation without any cover of hyphae was developed. Crozier formation could then be studied by timelapse cinematography of living material combined with other techniques to reveal the karyology. As a result we have traced a complete course of crozier chain formation obtained from individual crozier initials. Important deviations from the classical scheme of crozier development were found.

The ultrastructure of septal pores and associated structures in the ascogenous hyphae and asci ofSordaria humana

Septal pores and associated structures have been studied in ascogenous hyphae, croziers and asci ofSordaria humana by means of electron microscopy of serial and random sections. Pores exhibit variable structures from relatively simple pore caps to complex swollen rims with associated membrane cisternae. The simple types are found at the base of the ascogenous hyphae while the complex forms occur at the apex, in the croziers and in very young, presporulation asci. Post-sporulation asci contain a relatively simple type of pore structure. Cells which subtend the ascogenous hyphae exhibit both open and capped pores in their cross walls. Pore structures may be asymmetric in which case they show greater complexity on the side of the cross wall nearest to the apex or crozier. Membranous components of the complex pores are continuous with the endomembrane systems of the two adjacent cells and thus with the outer membranes of the nuclear envelopes. Membrane continuities may connect prefusion nuclei or fusion nuclei in penultimate cells, with nuclei of the stalk and terminal cells of croziers. Some speculation is presented as to the implication and possible roles of these structures in relation to cell differentiation within the ascogenous hyphae and croziers.

Direct studies of dikaryotization in Schizophyllum commune. II. Behavior and fate of multikaryotic hyphase.

The growth, duplication and fate of multikaryotic hyphae bearing true clamp connections, as derived from compatible matings of Schizophyllum commune, were studied by phase contrast microscopy. The nuclei (N) of multikaryotic apices maintained a near central position during hyphal growth. True clamp connection formation occurred with near synchronous mitosis followed by septal synthesis across the clamp neck and main hyphal axis. Nuclear progeny after mitosis in a hexakaryon included 6 N in the apex, 1 N in the clamp and 5 N in the penultimate cell; the solitary nucleus in the clamp later entered the penultimate cell. Similar events occurred for clamp connection formation and mitosis in the trikaryon, quadrikaryon or pentakaryon, whether in the apex or primary branches. Nuclear content of the multikaryotic apex (2 N through 10 N) had no apparent effect on the rate of individual hyphal growth. Reduction of the nuclear number in a trikaryon occurred by long-term entrapment of a solitary nucleus in the clamp and subsequent outgrowth of the dikaryotic penultimate cell. Occasionally, more than one nucleus became entrapped in the clamp cell. The ephemeral nature of the multikaryon was indicated by the fact that older cultures appeared to be exclusively dikaryotic hyphae at the colony periphery.

Relocation of species ofEndophragmiaauct. with notes on relevant generic names

Abstract The generic name Endophragmia Duvernoy et Maire is considered untenable for more than 30 species that have been included in it. In many of these species conidia secede rhexolytically. and percurrent proliferations arise from the penultimate cell of the conidiophore and of the successive proliferations: most of these particular species are transferred to Endophragmiella Sutton. Two species described in Endophragmiella are excluded from this genus and two new species described. Several species of “Endophragmia” are included in or transferred to Sporidesmium, Phragmocephala, Acremoniula, Paradendryphiopsis, and a new genus Melanocephala. Brief accounts are presented on other fonn genera with Endophragmiella-like proliferations after rhexolytic conidium secession, namely Teratosperma, Arachnophora, Acrophragmis, Chaetendophragmia, and Uberispora. Brief notes are also given on genera which, for various reasons, are involved in the redispositions of species assigned to Endophragmia, namely Domingoella,...

A CYTOPHOTOMETRIC INVESTIGATION OF THE RELATIONSHIP OF DNA AND RNA SYNTHESIS TO ASCUS DEVELOPMENT INSORDARIA FIMICOLA

Results from quantitative cytochemical analyses of Feulgen-DNA and azure B-RNA content of different stages of ascus development in the pyrenomycete Sordaria fimicola Ces. and DeNot. may be summarized as follows: (a) DNA replication in nuclei of the prefusion ascus (penultimate cell) precedes karyogamy, hence the prefusion nuclei are 2C (replicated haploid), and the fusion nucleus 4C (replicated diploid) in DNA content. These data show that premeiotic S phase and genetic recombination cannot be coincident since DNA replication is complete prior to nuclear fusion in the crozier penultimate cell. (b) DNA replication in the basal and terminal cell nuclei of the crazier does not occur until DNA replication is complete in the subterminal (penultimate) cell. Therefore, DNA replication occurs first in the cell which forms the primary ascus. (c) During ascus enlargement, which occurs during pachytene and diplotene, the total ascus RNA content increases from 18.9 to 195.4 arbitrary units (a.u.), while at the same time nucleolar RNA increases from 0.5 to 1.7 a.u. The concurrent increase in nucleolar and ascus RNA suggests that a rather substantial proportion of the increase in total ascus RNA may be due to the synthesis of ribosomal RNA. (d) In asci which contain binucleate ascospores the total RNA content has increased to 281.5 units. This increase may represent a storage of RNA to be utilized for protein synthesis during the subsequent germination of the ascospore. (e) Ascospores in mature asci of eight day old cultures were always multinucleate. The multinucleate condition is presumably established in preparation for ascospore germination and the initial growth of the germ tube.

CYTOLOGY OF THE ASCUS AND ASCOCARP DEVELOPMENT IN ACHAETOMIUM UNIAPICULATUM

The paper deals with the development of ascocarp and nuclear behaviour during the development of ascus and ascospores in Achaetomium uniapiculatum. The ascocarp arises by the coiling of a hyphal branch. The septate ascogonial coil soon becomes surrounded by the vegetative hyphae forming a pseudoparenchymatous spherical body which in later stages gets differentiated into wall layers and central sporogenous tissue. The ascus originates from the penultimate cell of the crozier produced by the binucleate ascogenous cells. As in most of the ascomycetes, in A. uniapiculatum also, four divisions follow karyogamy resulting in binucleate ascospores, each mature ascospore only has a single nucleus the other nucleus probably degenerates. The haploid number of chromosome is 5 (n=5).

Cytology of the Ascus in Achaetomium strumarium Rai, Tewari, and Mukerji

The cytology of ascus development in Achaetomium strumarium was studied using BAC (butyl alcohol, acetic acid, chromic acid) fixative and propiono-iron-hematoxylin stain The ascus initial is the binucleate penultimate cell of the crozier Karyogamy generally takes place in this penultimate cell. Pachytene and diplotene stages of prophase of meiosis I are prominent Diakinesis is transitory and rarely observed The nucleolus becomes diffuse at late diplotene and disappears by metaphase. Asynchronous disjunction was observed at anaphase of divisions III and IV Division IV starts after the ascospores are delimited Mature ascospores are binucleate The chromosome number assigned to this species is 7 (n = 7).

Light and Electron Microscopic Studies of Crozier Development in Pyronema domesticum

SUMMARY: The ultrastructural features of developing croziers are similar to those described in other ascomycete hyphal elements. The variations in vacuolation during development suggest that vacuoles control the movement of cytoplasm. Conjugate nuclear division occurs in the crozier before segmentation. During this division the continuous spindle fibres of the two nuclei are essentially parallel and extend from polar centriolar plaques. All the observations made with the electron microscope indicate that the nuclear envelope remains intact during division. After conjugate nuclear division the terminal cell is delimited. Subsequently, a septum is formed between the penultimate cell and the stalk cell. Both septa are formed by an inward deposition of wall material and possess a single central pore. The walls between a portion of the stalk and terminal cells dissolve and protoplasmic continuity is established between the two hyphal elements.

CYTOLOGY OF THE ASCUS IN ACHAETOMIUM GLOBOSUM AND A. LUTEUM

The cytology of the ascus in Achaetomium globosum and A. luteum was studied using BAC (butanol-acetic acid-chromic acid, 3:2:1) fixative and propiono-iron-haematoxylin stain. Ascus initial is the binucleate penultimate cell of the crozier. In A. luteum pachytene chromosomes are very long, easily countable, and the nucleolar organizer is clearly distinct. In general, divisions I and III stages are prominent in both the species studied, while division II stages are less frequent. Division IV starts during the delimitation of ascospores and continues in the mature ascospores. The chromosome number as counted from metaphase III configurations in A. globosum and pachytene configurations in A. luteum is 7 (n=7).