scholarly journals Cellular and topochemical characteristics of secondary changes in bark tissues of beech (Fagus sylvatica)

Holzforschung ◽  
2012 ◽  
Vol 66 (1) ◽  
Author(s):  
Peter Prislan ◽  
Gerald Koch ◽  
Uwe Schmitt ◽  
Jožica Gričar ◽  
Katarina Čufar
Keyword(s):  
Fagus Sylvatica ◽  
Cell Walls ◽  
Spectral Characteristics ◽  
Forest Site ◽  
Uv Absorbance ◽  
Average Width ◽  
Transmission Electron ◽  
Sieve Tubes ◽  
Xylem Fibers ◽  
Uv Microspectrophotometry

Abstract Anatomical and histometrical investigations were carried out on bark tissues (non-collapsed and collapsed phloem, and periderm) of beech (Fagus sylvatica L.) trees growing at a forest site near Ljubljana, Slovenia (400 m a.s.l.). Secondary changes in bark, especially sclereid formation and lignification, were followed at cellular and sub-cellular levels by light microscopy (LM), UV microspectrophotometry (UMSP), and transmission electron microscopy (TEM). The average width of the whole bark was 5960 μm; non-collapsed phloem on average occupied 4%, collapsed phloem 89%, and periderm 7% of the bark. Secondary changes in mature phloem were characterized by a collapse of sieve tubes, inflation of axial parenchyma, and development of sclereids. The percentage of sclereid areas and the stage of their development elevated with increasing distance from the cambium. The most pronounced increment in the sclereid proportion was observed in the second- and third-fifth of the bark. Sclereid cell walls were thick and poly-lamellated and had similar spectral characteristics but distinctly higher UV absorbance values than xylem fibers. By means of a combination of LM, TEM and UMSP techniques, the structure and secondary changes in the bark could be precisely identified.

scholarly journals Anatomy, Cell Wall Structure and Topochemistry of Water-Logged Archaeological wood aged 5,200 and 4,500 years

IAWA Journal ◽  
2008 ◽  
Vol 29 (1) ◽  
pp. 55-68 ◽  
Author(s):  
Katarina Čufar ◽  
Jožica Gričar ◽  
Martin Zupančič ◽  
Gerald Koch ◽  
Uwe Schmitt
Keyword(s):  
Cell Types ◽  
Wall Structure ◽  
Normal Wood ◽  
Uv Absorbance ◽  
Archaeological Wood ◽  
Transmission Electron ◽  
Parenchyma Cells ◽  
Prehistoric Settlements ◽  
And Storage ◽  
Uv Microspectrophotometry

Evaluating the state of deterioration of water-logged archaeological wood is necessary in order to select treatments for its conservation and storage, particularly in the case of valuable archaeological artefacts. For this purpose archaeological wood of ash (Fraxinus sp.) and oak (Quercus sp.) buried in water-logged conditions at prehistoric settlements on the Ljubljansko barje (Ljubljana moor), Slovenia, aged approx. 5,200 and 4,500 years, was investigated by means of light microscopy (LM), transmission electron microscopy (TEM) and cellular UV-microspectrophotometry (UMSP). LM and TEM revealed that the ash wood aged 5,200 years was the least preserved. The secondary walls of fibres, vessels and parenchyma cells were considerably thinner than in normal wood, indicating distinct degradation. TEM and UMSP additionally revealed strong delignification of the remaining parts of the secondary walls of all cell types. The compound middle lamellae appeared structurally intact, but had lower UV-absorbance than normal wood of the same species. The cell corners were topochemically unchanged, as shown by high analogue UV-absorbance. The UV-absorbance maxima at a wavelength of 278 nm corresponded to those of hardwood lignins. The oak heartwood was generally better preserved than the ash wood. Within each species, the 4,500- year-old samples generally appeared better preserved than those 5,200 years old.

Intervessel Pit Structure and Histochemistry of Two Mangrove Species as Revealed by Cellular UV Microspectrophotometry and Electron Microscopy: Intraspecific Variation and Functional Significance

2008 ◽  
Vol 14 (5) ◽  
pp. 387-397 ◽  
Author(s):  
Nele Schmitz ◽  
Gerald Koch ◽  
Uwe Schmitt ◽  
Hans Beeckman ◽  
Nico Koedam
Keyword(s):  
Electron Microscopy ◽  
Hydraulic Conductivity ◽  
Functional Significance ◽  
Rainy Season ◽  
Cell Walls ◽  
Avicennia Marina ◽  
Rhizophora Mucronata ◽  
Mangrove Species ◽  
Transmission Electron ◽  
Uv Microspectrophotometry

AbstractIntervessel pits play a key role in trees' water transport, lying at the base of drought-induced embolism, and in the regulation of hydraulic conductivity via hydrogels bordering pit canals. Recently, their microstructure has been the focus of numerous studies, but the considerable variation, even within species and the histochemistry of pit membranes, remains largely unexplained. In the present study, intervessel pits of the outermost wood were examined for Avicennia marina, of dry and rainy season wood separately for Rhizophora mucronata. The thickness of the pit membranes was measured on transmission electron micrographs while their topochemical nature was also analyzed via cellular UV microspectrophotometry. Pit membranes of R. mucronata were slightly thicker in dry season wood than in rainy season wood, but their spectra showed for both seasons a lignin and a yet unidentified higher wavelength absorbing component. It was suggested to be a derivative of the deposits, regularly filling pit canals. The vestures of A. marina chemically resembled pit membranes rather than cell walls.

Ultrastructure of commercial recycled pulp fibers for the production of packaging paper

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 675-680 ◽  
Author(s):  
Jonas Brändström ◽  
Jean-Paul Joseleau ◽  
Alain Cochaux ◽  
Nathalie Giraud-Telme ◽  
Katia Ruel
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Significant Proportion ◽  
Pulp Fibers ◽  
Chemical Pulp ◽  
Recycled Pulp ◽  
Transmission Electron ◽  
Large Heterogeneity ◽  
Recycled Fibers ◽  
Packaging Paper

Abstract Transmission electron microscopy was used to investigate the ultrastructure of recycled pulp fibers originating from a household collection plant and intended for the production of packaging paper. Three recovered paper grades and recycling processes, including pulping, screening, cleaning and refining, were assessed with emphasis on surface and internal fibrillation as well as xylan localization. Results showed a large heterogeneity with respect to fiber ultrastructure within and between the grades. Screening and cleaning steps had no detectable effects, but refining clearly increased cell-wall delamination and surface fibrillation. Immunolabeling of xylans showed that they were distributed rather evenly across the cell walls. They were also present on fines. Two different mechanisms for fiber delamination and surface fibrillation were found, one which implies that internal and external fibrillation take place simultaneously across the cell wall, and another which implies successive peeling of layers or sub-layers from the outside towards the inside. It is suggested that recycled fibers of chemical pulp origin undergo the former mechanism and recycled fibers that contain lignin binding the cell wall matrix give rise to the latter peeling mechanism. Because several recycled fibers were severely delaminated and almost fractured, we suggest that to produce a good packaging paper, it is important that recycled pulp should contain a significant proportion of fibers with high intrinsic strength.

scholarly journals Characterization of Passage-Selected Vancomycin-Resistant Staphylococcus aureus Strains of Diverse Parental Backgrounds

2000 ◽  
Vol 44 (2) ◽  
pp. 294-303 ◽  
Author(s):  
Richard F. Pfeltz ◽  
Vineet K. Singh ◽  
Jennifer L. Schmidt ◽  
Michael A. Batten ◽  
Christopher S. Baranyk ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Walls ◽  
Methicillin Resistance ◽  
Surface Hydrophobicity ◽  
Whole Cell ◽  
Transmission Electron ◽  
Vancomycin Mics ◽  
Vancomycin Resistant ◽  
Doubling Times

ABSTRACT A series of 12 Staphylococcus aureus strains of various genetic backgrounds, methicillin resistance levels, and autolytic activities were subjected to selection for the glycopeptide-intermediate S. aureus (GISA) susceptibility phenotype on increasing concentrations of vancomycin. Six strains acquired the phenotype rapidly, two did so slowly, and four failed to do so. The vancomycin MICs for the GISA strains ranged from 4 to 16 μg/ml, were stable to 20 nonselective passages, and expressed resistance homogeneously. Neither ease of acquisition of the GISA phenotype nor the MIC attained correlated with methicillin resistance hetero- versus homogeneity or autolytic deficiency or sufficiency. Oxacillin MICs were generally unchanged between parent and GISA strains, although the mec members of both isogenic methicillin-susceptible and methicillin-resistant pairs acquired the GISA phenotype more rapidly and to higher MICs than did their susceptible counterparts. Transmission electron microscopy revealed that the GISA strains appeared normal in the absence of vancomycin but had thickened and diffuse cell walls when grown with vancomycin at one-half the MIC. Common features among GISAs were reduced doubling times, decreased lysostaphin susceptibilities, and reduced whole-cell and zymographic autolytic activities in the absence of vancomycin. This, with surface hydrophobicity differences, indicated that even in the absence of vancomycin the GISA cell walls differed from those of the parents. Autolytic activities were further reduced by the inclusion of vancomycin in whole-cell and zymographic studies. The six least vancomycin-susceptible GISA strains exhibited an increased capacity to remove vancomycin from the medium versus their parent lines. This study suggests that while some elements of the GISA phenotype are strain specific, many are common to the phenotype although their expression is influenced by genetic background. GISA strains with similar glycopeptide MICs may express individual components of the phenotype to different extents.

Lignin distribution in waterlogged archaeological Picea abies (L.) Karst degraded by erosion bacteria

Holzforschung ◽  
2014 ◽  
Vol 68 (7) ◽  
pp. 791-798 ◽  
Author(s):  
Nanna Bjerregaard Pedersen ◽  
Uwe Schmitt ◽  
Gerald Koch ◽  
Claus Felby ◽  
Lisbeth Garbrecht Thygesen
Keyword(s):  
Picea Abies ◽  
Lignin Content ◽  
Middle Lamella ◽  
Uv Absorbance ◽  
Tem Analysis ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
Residual Material ◽  
Ray Parenchyma Cells ◽  
Very High

Abstract The lignin distribution in poles of waterlogged archaeological Picea abies (L.) Karst, which was decayed by erosion bacteria (EB) under anoxic conditions for approximately 400 years, was topochemically identified by transmission electron microscopy (TEM) and high resolution UV-microspectrophotometry (UMSP). Lignin rich cell wall compartments such as cell corner (CC), compound middle lamella (CML), torus, initial pit border and mild compression wood (CW) appeared morphologically well preserved together with S1 and S3 layers and epithelial and ray parenchyma cells. Residual material (RM) from degraded S2 showed a varied lignin distribution as evidenced by the different local UV-absorbance intensities. However, evaluation of UV-absorbance line spectra of RM revealed no change in conjugation of the aromatic ring system. Presence of RM with both very low and very high lignin absorbances showed evidence for disassembly of lignin during degradation combined with aggregation of lignin fragments and physical movement of these fractions. In contrast to TEM analysis, locally decreasing lignin content was found by UMSP in CML regions.

scholarly journals The Influence of Scandium on the Composition and Structure of the Ti-Al Alloy Obtained by “Hydride Technology”

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 918
Author(s):  
Natalia Karakchieva ◽  
Olga Lepakova ◽  
Yuri Abzaev ◽  
Victor Sachkov ◽  
Irina Kurzina
Keyword(s):  
Rietveld Method ◽  
Al Alloy ◽  
Surface Strength ◽  
Average Width ◽  
Near Surface ◽  
X Ray ◽  
Lamellar Structures ◽  
Quantitative Content ◽  
Transmission Electron ◽  
Composition And Structure

In this study the influence of scandium on the structural and phase state of the Ti-Al alloy obtained by the method of “Hydride Technology” (HT). The Rietveld method has allowed for determining the content of basic phases of the 49at.%Ti-49at.%Al-2at.%Sc system. By means of the methods of transmission electron microscopy (TEM) and X-ray spectral microanalysis, it has been established that scandium additives into the Ti-Al system result in the change of the quantitative content of phases in local regions of the structure. The Ti2Al5 phase has been found, and Ti2Al has been absent. In the morphology of substructures Ti-Al and Ti-Al-Sc there are lamellar structures or lamellae; the peculiarities of the distribution, fraction and size of which are influenced by scandium additives. The average width of Al-rich lamellae has been 0.85 µm, which is four times greater than that for the Ti-Al system (0.21 µm). For Ti-rich lamellae of the sample of the Ti-Al-Sc alloy, the average width of the lamellae has been 0.54 µm, and for Ti-Al it has been 0.34 µm. Based on the obtained data, a scheme of the distribution of phases in the composition of the Ti-Al-Sc alloy in the lamellar structures has been proposed. It has been established that in the Ti-Al-Sc system there is growth of the near-surface strength relative to Ti-Al. In this way, the microhardness of the Ti-Al-Sc alloy has amounted to 1.7 GPa, that is of the Ti-Al alloy which is 1.2 GPa.

scholarly journals Исследование электрофизических свойств квантовых точек антимонида индия: значение формы

2021 ◽  
Vol 55 (3) ◽  
pp. 237
Author(s):  
В.Ф. Кабанов ◽  
А.И. Михайлов ◽  
М.В. Гавриков
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Indium Antimonide ◽  
Spectral Characteristics ◽  
Characteristic Size ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Transmission Electron ◽  
Particle Size Analyzer ◽  
Characteristics Analysis

In this work, we studied the influence of the shape of the indium antimonide quantum dots of on some important electrophysical parameters by spectral characteristics analysis, transmission electron microscopy, scanning tunneling microscopy, a laser particle size analyzer, and scanning electron microscopy. It is shown that the real form of quantum dots (spherical and cubic models) at the same characteristic size will noticeably affect the energy spectrum of the investigated objects and, accordingly, their electrophysical and optical properties.

scholarly journals Submicroscopical Features of Leaves of Xyris Species

2001 ◽  
Vol 44 (4) ◽  
pp. 405-410 ◽  
Author(s):  
Maria das Graças Sajo ◽  
Silvia Rodrigues Machado
Keyword(s):  
Electron Microscope ◽  
Cell Walls ◽  
Guard Cells ◽  
Leaf Ultrastructure ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Inner Surface ◽  
Stomatal Guard Cells ◽  
Adaptative Significance ◽  
Scanning Electron

The leaf ultrastructure of five Xyris species were examined using scanning electron microscope (SEM), transmission electron microscope (TEM) and histochemical methods. All studied leaves show some features in epidermis and mesophyll, which were of considerable adaptative significance to drought stress. Such features included the occurrence of a pectic layer on the stomatal guard cells and the presence of a network of pectic compounds in the cuticle. Pectic compunds were also in abundance in lamellated walls of the mesophyll cells and on the inner surface of the sclerified cell walls of the vascular bundle sheaths. There were also specialized chlorenchymatous "peg cells" in the mesophyll and drops of phenolic compounds inside the epidermal cells.

Soil Colloids and Soil Organic Matter Associativity - the Basis of Soil Structure

2001 ◽  
Vol 7 (S2) ◽  
pp. 534-535
Author(s):  
G. Vrdoljak ◽  
G. Sposito
Keyword(s):  
Electron Microscopy ◽  
Nmr Spectroscopy ◽  
Soil Structure ◽  
Size Fraction ◽  
Research Station ◽  
Forest Site ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Highly Weathered Soils

In the hierarchical model of soil structure, the lowest scale of structure is the combination of clays < 0.2 um diameter to form 2 um domains. to investigate the basis for soil structure, two highly weathered soils from Brazil (Oxisols) were selected and the < 2 um size fraction extracted by sedimentation for analysis. The first soil used in this study, classified as Xanthic Hapludox, was collected in 1991 at an EMBRAPA research station outside of Manaus, Brazil from a tropical forest site collected from the 0-8 cm depth. The second soil (0-20 cm depth) was sampled from a topographically flat area inside the Brasilia National Park, Brasilia D.F. Brazil by Dr. Flavio Vasconcelos.The samples were analyzed by NMR spectroscopy, transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. NMR spectroscopy revealed the organic materials within this size fraction consisted predominantly of polysaccharides.

scholarly journals The Fungicide Tetramethylthiuram Disulfide Negatively Affects Plant Cell Walls, Infection Thread Walls, and Symbiosomes in Pea (Pisum sativum L.) Symbiotic Nodules

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1488
Author(s):  
Artemii P. Gorshkov ◽  
Anna V. Tsyganova ◽  
Maxim G. Vorobiev ◽  
Viktor E. Tsyganov
Keyword(s):  
Pisum Sativum ◽  
Cell Walls ◽  
Infection Thread ◽  
Nodule Development ◽  
Starch Accumulation ◽  
Ultrastructural Organization ◽  
Negative Effects ◽  
Tetramethylthiuram Disulfide ◽  
Transmission Electron ◽  
Nodule Senescence

In Russia, tetramethylthiuram disulfide (TMTD) is a fungicide widely used in the cultivation of legumes, including the pea (Pisum sativum). Application of TMTD can negatively affect nodulation; nevertheless, its effect on the histological and ultrastructural organization of nodules has not previously been investigated. In this study, the effect of TMTD at three concentrations (0.4, 4, and 8 g/kg) on nodule development in three pea genotypes (laboratory lines Sprint-2 and SGE, and cultivar ‘Finale’) was examined. In SGE, TMTD at 0.4 g/kg reduced the nodule number and shoot and root fresh weights. Treatment with TMTD at 8 g/kg changed the nodule color from pink to green, indicative of nodule senescence. Light and transmission electron microscopy analyses revealed negative effects of TMTD on nodule structure in each genotype. ‘Finale’ was the most sensitive cultivar to TMTD and Sprint-2 was the most tolerant. The negative effects of TMTD on nodules included the appearance of a senescence zone, starch accumulation, swelling of cell walls accompanied by a loss of electron density, thickening of the infection thread walls, symbiosome fusion, and bacteroid degradation. These results demonstrate how TMTD adversely affects nodules in the pea and will be useful for developing strategies to optimize fungicide use on legume crops.

Sign in / Sign up

Export Citation Format

Share Document