Modes of cell-wall degradation of Sphagnum fuscum by Acremonium cf. curvulum and Oidiodendron maius

2001 ◽  
Vol 79 (1) ◽  
pp. 93-100 ◽  
Author(s):  
A Tsuneda ◽  
M N Thormann ◽  
R S Currah
Keyword(s):  
Cell Walls ◽  
Amorphous Matrix ◽  
Matrix Material ◽  
Outer Wall ◽  
Amorphous Layer ◽  
Wall Layer ◽  
Sphagnum Fuscum ◽  
The Matrix ◽  
Oidiodendron Maius ◽  
Wall Components

Electron microscopy of cryo-fractured hyaline leaf cells of Sphagnum fuscum Klinggr. revealed that their cell walls consist of three layers: a thick central layer flanked on either side by a thinner, amorphous layer. Acremonium cf. curvulum W. Gams and Oidiodendron maius Barron, both isolated from partly decomposed S. fuscum plants, were capable of degrading leaf cell walls of Sphagnum. Where hyphae of A. curvulum accumulated, the amorphous, outer wall layer of S. fuscum was first fragmented and then removed. The exposed central wall layer consisted of bundles of microfibrils embedded in an amorphous matrix material. After the matrix material and the inner surface wall layer were mostly removed, degradation of microfibrils occurred and localized voids were produced. Unlike A. cf. curvulum, O. maius degraded all wall components more or less simultaneously. In both fungi, active and autolysing hyphae frequently occurred in proximity on the Sphagnum leaves.Key words: hyphomycetes, peat, phenolics, cellulose, SEM.

scholarly journals Partial disassembly of peroxisomes.

1985 ◽  
Vol 101 (1) ◽  
pp. 294-304 ◽  
Author(s):  
S E Alexson ◽  
Y Fujiki ◽  
H Shio ◽  
P B Lazarow
Keyword(s):  
Amorphous Matrix ◽  
Matrix Material ◽  
Matrix Proteins ◽  
Beta Oxidation ◽  
Freezing And Thawing ◽  
Fibrillar Material ◽  
Sds Page ◽  
The Matrix ◽  
Poorly Soluble ◽  
Liver Peroxisomes

Rat liver peroxisomes were subjected to a variety of procedures intended to partially disassemble or damage them; the effects were analyzed by recentrifugation into sucrose gradients, enzyme analyses, electron microscopy, and SDS PAGE. Freezing and thawing or mild sonication released some matrix proteins and produced apparently intact peroxisomal "ghosts" with crystalloid cores and some fuzzy fibrillar content. Vigorous sonication broke open the peroxisomes but the membranes remained associated with cores and fibrillar and amorphous matrix material. The density of both ghosts and more severely damaged peroxisomes was approximately 1.23. Pyrophosphate (pH 9) treatment solubilized the fibrillar content, yielding ghosts that were empty except for cores. Some matrix proteins such as catalase and thiolase readily leak from peroxisomes. Other proteins were identified that remain in mechanically damaged peroxisomes but are neither core nor membrane proteins because they can be released by pyrophosphate treatment. These constitute a class of poorly soluble matrix proteins that appear to correspond to the fibrillar material observed morphologically. All of the peroxisomal beta-oxidation enzymes are located in the matrix, but they vary greatly in how easily they leak out. Palmitoyl coenzyme A synthetase is in the membrane, based on its co-distribution with the 22-kilodalton integral membrane polypeptide.

Sporopollenin in the cell walls of Coccomyxa and Myrmecia phycobionts of various lichens: an ultrastructural and chemical investigation

1981 ◽  
Vol 59 (12) ◽  
pp. 2713-2734 ◽  
Author(s):  
Rosmarie Honegger ◽  
Ueli Brunner
Keyword(s):  
Mother Cell ◽  
Cell Walls ◽  
Freeze Fracture ◽  
Thick Layer ◽  
Outer Wall ◽  
Wall Layer ◽  
Middle Part ◽  
Wall Structure ◽  
Thin Sections ◽  
Ir Spectrophotometry

Symbiotic and cultivated Myrmecia phycobionts of Baeomyces rufus and Coccomyxa phycobionts of five different asco- and basidio-lichens were investigated with cytological and chemical methods. The cell wall structure of the free-living type species Coccomyxa dispar was compared with that of the lichen phycobionts.Three different wall layers were observed in all Coccomyxa and Myrmecia cells investigated. An innermost, variably thick layer is amorphous in structure and is built up mainly by Golgi-derived hemicelluloses. An outer wall layer, uniformly thick, appears electron dense in thin sections and exhibits short, probably cellulosic fibrils embedded in an amorphous matrix in freeze-fracture preparations. Beyond these two wall layers is an outermost trilaminar wall layer of uniform thickness in all species investigated. It contains sporopollenin in its electron-transparent, rigid middle part; proteinlike particles are embedded in an amorphous, carbohydrate-containing matrix on its electron-dense inner and outer surfaces. IR spectrophotometry of acetolysis-resistant material yielded data comparable with those of other sporopollenin-containing algal walls, although the Coccomyxa and Myrmecia sporopollenin did not dissolve in chromic acid. The trilaminar layer is not lysed during or after autospore formation. Persistent mother cell walls were detected in all lichen thalli investigated, as well as in the culture medium of isolated phycobionts. Persistent mother cell walls were also found in the gelatinous sheath of Coccomyxa dispar.This type of wall structure affords protection against fungal parasitism and may be a significant factor in the success of some lichens and some other symbiotic systems.

Ultrastructural studies on the cell walls in Fusarium sulphureum

1979 ◽  
Vol 25 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Edward F. Schneider ◽  
Alan B. Wardrop
Keyword(s):  
Cell Walls ◽  
Outer Wall ◽  
Wall Layer ◽  
Additional Treatment ◽  
Degree Of Crystallinity ◽  
Thick Wall ◽  
Wall Material ◽  
Fungal Cell ◽  
Ultrastructural Studies ◽  
Fusarium Sulphureum

The cell walls of Fusarium sulphureum have a microfibrillar component that is randomly arranged. X-ray-diffraction diagrams of the microfibrils are consistent with a high degree of crystallinity and show that they are chitin. The chitin microfibrils of the peripheral walls envelop the hyphal apex and extend across the septae. During the first 8 h in culture, the conversion of conidial cells to chlamydospores is evidenced by a swelling of the cells and the original microfibrils remain randomly arranged. Within 24 h new wall material is deposited as the cells expand and the wall thickens. The new microfibrils are indistinguishable from those of the original conidial cells.After 3 days in culture, the chlamydospores are fully developed and have the characteristic thick wall which is a continuous layer of randomly arranged microfibrils. Chlamydospores maintained in a conversion medium for 8 days have microfibrils identical with those in 3-day-old cultures; thus a further change in the microfibril orientation did not occur during that period.Alkaline hydrolysis of the walls removes most of the electron-dense staining constituents from the inner wall layer and leaves the outer wall layer intact. This treatment also reveals some of the wall microfibrils. An additional treatment of the walls with HAc/H2O2 completely removes the wall components that react positively to heavy metal stains. The results are discussed in relation to the structure of other fungal cell walls.

Cell wall of Fusarium sulphureum. II. Chemical composition of the conidial and chlamydospore walls

1977 ◽  
Vol 23 (6) ◽  
pp. 763-769 ◽  
Author(s):  
E. F. Schneider ◽  
L. R. Barran ◽  
P. J. Wood ◽  
I. R. Siddiqui
Keyword(s):  
Cell Wall ◽  
Glucuronic Acid ◽  
Dry Weight ◽  
Outer Wall ◽  
Wall Layer ◽  
Dense Layer ◽  
Glucose Content ◽  
Fusarium Sulphureum ◽  
Spore Walls ◽  
Wall Components

Examination of the conidial and chlamydospore walls of Fusarium sulphureum by electron microscopy showed the presence of two distinct layers of differing electron densities. These include a relatively narrow outer electron-dense layer and a broader more transparent inner layer. Both chlamydospore cell wall layers were thicker than the conidial wall. The outer wall of the chlamydospore wall was 30% thicker while the inner cell wall layer was 250% thicker than the corresponding cell wall layers in the conidia. During conidial differentiation to form chlamydospores there was a considerable augmentation of all cell wall components which varied from 7 to 26-fold per cell. The augmentation of the major cell wall constituents (N-acetylglucoseamine (NAG), glucose, and protein) and the vast increase in the inner cell wall of the chlamydospore wall indicated that these newly synthesized constituents are predominently located in the inner cell wall layer.The major carbohydrate constituents on a dry weight basis in both the conidial and chlamydospore walls were glucose, glucuronic acid, and N-acetylglycosamine (NAG). However, the proportion of these and the other carbohydrate constituents were different for both spore walls. Thus, the conidial wall contained about 50% less NAG and glucuronic acid but twice the glucose content of the chlamydospore wall. Protein was a major component of both spore walls (21.6%, conidial wall; 28.5%, chlamydospore wall). Amino acid analysis indicated differences in the types of protein present in the two spore walls. The lipid content of both conidia and chlamydospore was low (1–2%).

Multiscale Modeling Approach for Estimation of Pinhole Defects in Polymer Nanocomposites

NANO ◽  
2015 ◽  
Vol 10 (02) ◽  
pp. 1550030
Author(s):  
A. K. Gupta ◽  
S. P. Harsha
Keyword(s):  
Multiscale Modeling ◽  
Matrix Material ◽  
Three Dimensional ◽  
Load Condition ◽  
Outer Wall ◽  
Atomic Scale ◽  
Van Der Waals Interactions ◽  
Euler Beam ◽  
Modeling Approach ◽  
The Matrix

In this paper, a multiscale modeling approach is proposed for studying the pinhole defects in double wall carbon nanotube (DWNT) reinforced polymer composites. Two configurations of DWNT i.e., armchair (5,5), (10,10) and zigzag (9,0), (16,0) are selected for the analyses wherein C–C bonds at atomic scale are modeled as Euler beam. The three-dimensional (3D) solid elements are used for matrix material and square representative volume element (RVE) is constructed for the nanocomposite. These composite materials consist of aligned carbon nanotubes (CNTs) that are uniformly distributed within the matrix. The presence of chemical covalent bonding between functionalized CNT and matrix are modeled as elastic crosslinks. The nonbonded van der Waals interactions between inner and outer wall are modeled as cohesive interaction elements. The influence of the pinhole defects on the nanocomposite are studied under axial load condition. It has been observed that with the increase in the number of atomic vacancies, the elastic modulus of the composite are reduced significantly. The effects of nanotube chirality and composite stiffness ratio on the elastic properties are also analyzed in the presence of pinhole defects.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

Application of cross correlation to HREM images of surfaces

1987 ◽  
Vol 45 ◽  
pp. 754-755
Author(s):  
D. E. Luzzi ◽  
L. D. Marks ◽  
M. I. Buckett
Keyword(s):  
Cross Correlation ◽  
A Priori ◽  
Matrix Material ◽  
Correlation Method ◽  
Accurate Knowledge ◽  
Complex Image ◽  
Fourier Filtering ◽  
The Matrix ◽  
Low Pass ◽  
Data Reduction Technique

As the HREM becomes increasingly used for the study of dynamic localized phenomena, the development of techniques to recover the desired information from a real image is important. Often, the important features are not strongly scattering in comparison to the matrix material in addition to being masked by statistical and amorphous noise. The desired information will usually involve the accurate knowledge of the position and intensity of the contrast. In order to decipher the desired information from a complex image, cross-correlation (xcf) techniques can be utilized. Unlike other image processing methods which rely on data massaging (e.g. high/low pass filtering or Fourier filtering), the cross-correlation method is a rigorous data reduction technique with no a priori assumptions.We have examined basic cross-correlation procedures using images of discrete gaussian peaks and have developed an iterative procedure to greatly enhance the capabilities of these techniques when the contrast from the peaks overlap.

Impact Strength, Flexural Modulus and Wear Rate of PMMA Composites Reinforced by Eggshell Powders

2020 ◽  
Vol 38 (7A) ◽  
pp. 960-966
Author(s):  
Aseel M. Abdullah ◽  
Hussein Jaber ◽  
Hanaa A. Al-Kaisy
Keyword(s):  
Impact Strength ◽  
Wear Rate ◽  
Flexural Modulus ◽  
Matrix Material ◽  
Weight Fraction ◽  
Pure Pmma ◽  
Calcination Process ◽  
The Matrix ◽  
The Impact ◽  
Interface Bond

In the present study, the impact strength, flexural modulus, and wear rate of poly methyl methacrylate (PMMA) with eggshell powder (ESP) composites have been investigated. The PMMA used as a matrix material reinforced with ESP at two different states (including untreated eggshell powder (UTESP) and treated eggshell powder (TESP)). Both UTESP and TESP were mixed with PMMA at different weight fractions ranged from (1-5) wt.%. The results revealed that the mechanical properties of the PMMA/ESP composites were enhanced steadily with increasing eggshell contents. The samples with 5 wt.% of UTESP and TESP additions give the maximum values of impact strength, about twice the value of the pure PMMA sample. The calcination process of eggshells powders gives better properties of the PMMA samples compared with the UTESP at the same weight fraction due to improvements in the interface bond between the matrix and particles. The wear characteristics of the PMMA composites decrease by about 57% with increases the weight fraction of TESP up to 5 wt.%. The flexural modulus values are slightly enhanced by increasing of the ESP contents in the PMMA composites.

scholarly journals Self-Reinforced Nylon 6 Composite for Smart Vibration Damping

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1235
Author(s):  
Bidita Salahuddin ◽  
Rahim Mutlu ◽  
Tajwar A. Baigh ◽  
Mohammed N. Alghamdi ◽  
Shazed Aziz
Keyword(s):  
Matrix Material ◽  
Nylon 6 ◽  
Vibration Damping ◽  
Vibration Energy ◽  
Damping Factor ◽  
Passive Vibration Control ◽  
Reinforced Composite ◽  
Coiled Structure ◽  
The Matrix ◽  
3D Printed

Passive vibration control using polymer composites has been extensively investigated by the engineering community. In this paper, a new kind of vibration dampening polymer composite was developed where oriented nylon 6 fibres were used as the reinforcement, and 3D printed unoriented nylon 6 was used as the matrix material. The shape of the reinforcing fibres was modified to a coiled structure which transformed the fibres into a smart thermoresponsive actuator. This novel self-reinforced composite was of high mechanical robustness and its efficacy was demonstrated as an active dampening system for oscillatory vibration of a heated vibrating system. The blocking force generated within the reinforcing coiled actuator was responsible for dissipating vibration energy and increase the magnitude of the damping factor compared to samples made of non-reinforced nylon 6. Further study shows that the appropriate annealing of coiled actuators provides an enhanced dampening capability to the composite structure. The extent of crystallinity of the reinforcing actuators is found to directly influence the vibration dampening capacity.

Investigation on the Influence of Pressure Terms in a Volume-Averaged Energy Balance in the Modelling of Liquid Composite Moulding Processes

2019 ◽  
Vol 809 ◽  
pp. 480-486
Author(s):  
Rohit George Sebastian ◽  
Christof Obertscheider ◽  
Ewald Fauster ◽  
Ralf Schledjewski
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Balance ◽  
Matrix Material ◽  
Energy Balance Equation ◽  
Manufacturing Processes ◽  
Composite Manufacturing ◽  
Liquid Composite Moulding ◽  
The Matrix ◽  
Computational Fluid Dynamics Cfd

The growing use of composite materials has generated interest in improving and optimising composite manufacturing processes such as Liquid Composite Moulding (LCM). In LCM, dry preforms are placed in a mould and impregnated with the matrix material. The efficiency of filling the moulds can be improved by using Computational Fluid Dynamics (CFD) filling simulations during the design of the mould. As part of an on-going effort to develop a CFD tool for the simulation of LCM processes, a volume averaged energy balance equation has been derived and implemented in a custom OpenFOAM solver. The energy balance is implemented in a custom OpenFOAM solver with and without the pressure terms for comparison with results from RTM experiments. It is found that the pressure terms do not significantly influence the results for LCM processes.

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