scholarly journals THE MICROCRYSTALLINE STRUCTURE OF CELLULOSE IN CELL WALLS OF COTTON, RAMIE, AND JUTE FIBERS AS REVEALED BY NEGATIVE STAINING OF SECTIONS

1966 ◽  
Vol 29 (2) ◽  
pp. 181-197 ◽  
Author(s):  
A. N. J. Heyn
Keyword(s):  
Cell Walls ◽  
Spatial Arrangement ◽  
Negative Staining ◽  
X Ray Diffraction ◽  
Indirect Methods ◽  
X Ray ◽  
Jute Fibers ◽  
Ultrathin Sections ◽  
A New Technique ◽  
Microfibrillar Structure

With a new technique of negative staining of sections, it has been possible to observe directly, in ultrathin sections under the electron microscope, the original microcrystalline and microfibrillar structure of cellulose as it occurs in living cells. This method has advantages over the study of isolated fibers used so far by others, in that the original arrangement of microfibrils is better preserved, and their collapse into larger fibrillar units is prevented. With this method, the cell walls of ramie, jute, and cotton fibers have been studied. The size (diameter, 25 to 40 A) and the longitudinal periodicity observed in the single microfibrils and the orientation and spatial arrangement of the microcrystallite within the microfibrils are found to correspond with the latest models derived by others from data obtained by indirect methods such as X-ray diffraction. The microfibril size of about 35 A, found by measuring these structures in sections, agrees with the latest conclusions reached by others in recent work with isolated fibrils.

The location and analysis of melanins in the cell walls of some soil fungi

1974 ◽  
Vol 20 (10) ◽  
pp. 1379-1386 ◽  
Author(s):  
D. H. Ellis ◽  
D. A. Griffiths
Keyword(s):  
Cell Walls ◽  
Soil Fungi ◽  
Degradation Products ◽  
Published Data ◽  
X Ray Diffraction ◽  
Ir Radiation ◽  
X Ray ◽  
Ultrathin Sections ◽  
Plant Sources

Electron-dense particles of melanin were located in ultrathin sections of: the hyphal walls of Amorphotheca resume; the aleuriospore walls of Epicoccum nigrum and Humicola grisea; the sclerotial walls of Colletotrichum coccodes; and both within and between the microsclerotial cell walls of Verticillium dahliae. Melanin was extracted with KOH from each of the fungi, but, because of rapid oxidation of the pigment in air, extraction and analysis was carried out under nitrogen. The pigments were examined spectrophotometrically under UV and IR radiation and by means of x-ray diffraction. Characterization of the melanin in terms of its degradation products indicated it to be indolic in nature. These results are compared with published data on other melanins extracted from animal and plant sources.

The effects of thermal treatment on the nanomechanical behavior of bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) cell walls observed by nanoindentation, XRD, and wet chemistry

Holzforschung ◽  
2017 ◽  
Vol 71 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Yanjun Li ◽  
Chengjian Huang ◽  
Li Wang ◽  
Siqun Wang ◽  
Xinzhou Wang
Keyword(s):  
Cell Wall ◽  
Thermal Treatment ◽  
Cell Walls ◽  
Treatment Time ◽  
Lignin Content ◽  
Phyllostachys Pubescens ◽  
X Ray Diffraction ◽  
Wet Chemistry ◽  
X Ray ◽  
Wet Chemical

Abstract The effects of thermal treatment of bamboo at 130, 150, 170, and 190°C for 2, 4, and 6 h were investigated in terms of changes in chemical composition, cellulose crystallinity, and mechanical behavior of the cell-wall level by means of wet chemical analysis, X-ray diffraction (XRD), and nanoindentation (NI). Particularly, the reduced elastic modulus (Er), hardness (H), and creep behavior were in focus. Both the temperature and treatment time showed significant effects. Expectedly, the hemicelluloses were degraded and the relative lignin content was elevated, while the crystallinity of the cellulose moiety was increased upon thermal treatment. The Er and H data of the cell wall were increased after 6 h treatment at 190°C, from 18.4 to 22.0 GPa and from 0.45 to 0.65 GPa, respectively. The thermal treatment led to a decrease of the creep ratio (CIT) under the same conditions by ca. 28%. The indentation strain state (εi) also decreased significantly after thermal treatment during the load-holding stage.

A Novel Technique of Flyash Utilization: Preparation of Silica from Flyash by Alkali Leaching

2010 ◽  
Vol 434-435 ◽  
pp. 814-815
Author(s):  
An Ran Guo ◽  
Jia Chen Liu ◽  
Yi Bing Sun ◽  
Wen Jun Lian ◽  
Lu Yang
Keyword(s):  
High Purity ◽  
Sodium Hydroxide Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Novel Technique ◽  
Reinforcing Agent ◽  
Alkali Leaching ◽  
A New Technique ◽  
Fluorescence Spectrometer ◽  
Scanning Electron

A new technique of flyash utilization was presented and high-purity silica was prepared by alkali leaching. The flyash was added into sodium hydroxide solution, and then the suspension was heated to 115 °C for 30 min. After filtrated, the filtrate was collected and carbon dioxide was imported into the solution. Finally, the silica would precipitate from the solution. The silica was characterized by scanning electron microscopy, X-ray diffraction and X-ray fluorescence spectrometer. The high-purity silica prepared from flyash was qualified for the rubber reinforcing agent used in shoemaking.

scholarly journals Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 31 ◽  
Author(s):  
Shahrzad Arshadi Rastabi ◽  
Rasoul Sarraf Mamoory ◽  
Fatemeh Dabir ◽  
Nicklas Blomquist ◽  
Manisha Phadatare ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Ammonia Solution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Methods ◽  
Alkaline Environments ◽  
Pseudocapacitive Behavior ◽  
Ammonia Addition ◽  
A New Technique

Although Graphene oxide (GO)-based materials is known as a favorable candidate for supercapacitors, its conductivity needs to be increased. Therefore, this study aimed to investigate the performance of GO-based supercapicitor with new methods. In this work, an ammonia solution has been used to remove the oxygen functional groups of GO. In addition, a facile precipitation method was performed to synthesis a NiMoO4/3D-rGO electrode with purpose of using synergistic effects of rGO conductivity properties as well as NiMoO4 pseudocapacitive behavior. The phase structure, chemical bands and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Raman spectroscopy, and field emission secondary electron microscopy (FE-SEM). The electrochemical results showed that the NiMoO4/3D-rGO(II) electrode, where ammonia has been used during the synthesis, has a capacitive performance of 932 Fg−1. This is higher capacitance than NiMoO4/3D-rGO(I) without using ammonia. Furthermore, the NiMoO4/3D-rGO(II) electrode exhibited a power density of up to 17.5 kW kg−1 and an energy density of 32.36 Wh kg−1. These results showed that ammonia addition has increased the conductivity of rGO sheets, and thus it can be suggested as a new technique to improve the capacitance.

Wood Petrifaction: and aspect of biomineralogy

1979 ◽  
Vol 27 (4) ◽  
pp. 377 ◽  
Author(s):  
G Scurfield
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
X Ray Diffraction ◽  
Intercellular Substance ◽  
X Ray ◽  
Colloidal Form ◽  
Cell Lumina ◽  
Mineral Deposition ◽  
Wall Components ◽  
Scanning Electron

Light microscopy, scanning electron microscopy, X-ray diffraction and differential thermal analysis have been used to examine the structure and mineralogical make-up of 79 Australian petrified woods. Initiation of petrifaction appears to rely on the provision of a substrate with inherent porosity, with the substrate components chemically rather inert and only slowly degraded at normal temperatures and pressures under conditions probably most often acid and tending to anaerobic, and the pores sufficiently large to allow access of an appropriate mineral in ionic or colloidal form in water. Stages in the process include entry of mineral solution into the wood via splits or checks, cell lumina, and other voids; permeation of cell walls; progressive dissolution of cell wall components beginning largely with lignin and accompanied by a build-up of a mineral framework adequate for maintaining the dimensional stability of the wood; mineral deposition in cell lumina after cell wall replacement as a continuous, intermittent, perhaps separate, but not obligatory event; mineral deposition in voids present or formed by dissolution of intercellular substance as a separate, but not obligatory event; and final lithification involving loss of water and perhaps replacement of one mineral by another.

AN INTERLOCKING SINGLE-STRAND MODEL FOR FIBRIN POLYMERIZATION.

1987 ◽  
Author(s):  
E B Hunziker ◽  
P W Straub ◽  
A Haeberli
Keyword(s):  
Electron Microscopy ◽  
Experimental Data ◽  
Binding Sites ◽  
Intermediate Phase ◽  
Single Strand ◽  
Negative Staining ◽  
X Ray Diffraction ◽  
Fibrin Polymerization ◽  
X Ray ◽  
Polypeptide Chains

The early stages of fibrin polymerization were investigated by rotatory shadowing and electron microscopy. Individual molecules within initial oligomers were found to be unaligned and contacted neighbouring molecules by single E + D and D + E contacts, suggesting an intermediate phase of activation (des A-fibrin). The interacting molecular domains were separated by a distance of 2 to 3 nm, indicating that (both or at least one) binding sites are located on protruding segments of the polypeptide chains. Upon completion of fibrin activation (des AA-fibrin), molecules within the early oligomers aligned to form single-stranded polymers,o these being characterized by repeating trinodular units of 230 A in length. Based upon these findings, a new interlocking single-stranded model for fibrin polymerization was designed and tested. The model is consistent with previous experimental data on fibrin polymerization such as that obtained by X-ray diffraction and negative staining. Moreover, early branching and lateral association phenomena are easily explained.

Study of diffraction data sets using factor analysis: a new technique for comparing mineralogical and geochemical data and rapid diagnostics of the mineral composition of large collections of rock samples

2019 ◽  
Vol 34 (S1) ◽  
pp. S59-S70 ◽  
Author(s):  
Ekaterina Fomina ◽  
Evgeniy Kozlov ◽  
Svetlana Ivashevskaja
Keyword(s):  
Geochemical Data ◽  
Chemical Compositions ◽  
Data Sets ◽  
Rapid Diagnostics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Short Period ◽  
Diffraction Patterns ◽  
A New Technique

This paper presents an example of comparing geochemical and mineralogical data by means of the statistical analysis of the X-ray diffraction patterns and the chemical compositions of bulk samples. The proposed methodology was tested on samples of metasomatic rocks from two geologically different objects. Its application allows us to mathematically identify all the main, secondary and some accessory minerals, to qualitatively estimate the contents of these minerals, as well as to assess their effect on the distribution of all petrogenic and investigated trace elements in a short period of time at the earliest stages of the research. We found that the interpretation of the results is significantly influenced by the number of samples studied and the quality of diffractograms.

The resolution of individual protein subunits in ferritin

1978 ◽  
Vol 36 (2) ◽  
pp. 182-183
Author(s):  
William H. Massover
Keyword(s):  
Electron Microscopy ◽  
Storage Protein ◽  
Quaternary Structure ◽  
Negative Staining ◽  
Variable Amount ◽  
X Ray Diffraction ◽  
Iron Storage ◽  
Protein Subunits ◽  
X Ray ◽  
Iron Storage Protein

The technique of negative staining has been of very great value for directly determining the quaternary structure of individual multimeric proteins and viruses. In this regard, the iron-storage protein,, ferritin, is a notable exception for not having had its subunits unambiguously resolved by negative staining. Each ferritin molecule (d= 120Å) has an outer shell of 24 protein subunits (MW= 18,500) surrounding a variable amount of mineralized iron; published x-ray diffraction studies have not yet defined individual monomers in the polymeric shell. Claims that single subunits have been visualized in ferritin by electron microscopy (e.g.,6) all appear to be of highly doubtful validity since the phase granularity of the dried stain and supporting film has the same dimension as the presumed subunits; apparent subunits are readily visualized in defocused images, but are no longer discernable when brought closer to exact focus.

Sign in / Sign up

Export Citation Format

Share Document