scholarly journals A finger-jointing model for describing ultrastructures of cellulose microfibrils

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bunshi Fugetsu ◽  
Vipin Adavan Kiliyankil ◽  
Shoichi Takiguchi ◽  
Ichiro Sakata ◽  
Morinobu Endo
Keyword(s):  
Water Vapor ◽  
Cellulose Nanofibrils ◽  
Cellulose Microfibrils ◽  
Saturated Water Vapor ◽  
X Ray Diffraction ◽  
Saturated Water ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Long Fibers ◽  
Finger Jointing

AbstractIn this paper, we propose a finger-jointing model to describe the possible ultrastructures of cellulose microfibrils based on new observations obtained through heating of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNFs) in saturated water vapor. We heated the micrometers-long TEMPO-CNFs in saturated water vapor (≥ 120 °C, ≥ 0.2 MPa) and observed a surprising fact that the long TEMPO-CNFs unzipped into short (100 s of nanometers long) fibers. We characterized the heated TEMPO-CNFs using X-ray diffraction (XRD) and observed the XRD patterns were in consistent with Iβ. We observed also jointed ultrastructures on the heated TEMPO-CNFs via high-resolution transmission electron microscopy (HR-TEM). Thus we concluded that cellulose microfibrils are not seamlessly long structures, but serial jointed structures of shorter blocks. Polysaccharide chains of the short blocks organized in Iβ. The jointed region can be either Iα or amorphous, depending on positions and distances among the chains jointed in proximity. Under heating, Iα was not converted into Iβ but was simply destroyed. The jointed structure implies a “working and resting rhythm” in the biosynthesis of cellulose.

scholarly journals A finger-jointing model for describing nanostructures of cellulose microfibrils

2021 ◽  
Author(s):  
Bunshi Fugetsu ◽  
Adavan Kiliyankil Vipin ◽  
Shoichi Takiguchi ◽  
Ichiro Sakata ◽  
Morinobu Endo
Keyword(s):  
Water Vapor ◽  
Sustainable Development Goals ◽  
Cellulose Nanofibers ◽  
Cellulose Microfibrils ◽  
Cellulose Nanowhiskers ◽  
Saturated Water Vapor ◽  
Native Cellulose ◽  
Saturated Water ◽  
Development Goals ◽  
Finger Jointing

Abstract We propose a finger-jointing model to describe the possible nanostructures of native cellulose microfibrils based on new observations obtained through thermal decomposition of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofibers (CNFs) in saturated water vapor. We heated the micrometers-long TEMPO-CNFs in saturated water vapor (≥ 120 °C, ≥ 0.2 MPa) for ≤ 8 h. The long TEMPO-CNFs unzipped into short (100 s of nanometers long) cellulose nanowhiskers (CNWs). We characterized the CNWs using Raman spectroscopy and Fourier transform infrared spectroscopy, observing similar spectra as TEMPO-CNFs. Thus, the native cellulose microfibrils are not seamlessly long structures, but serial “jointed structures” of CNWs. The finger-jointing model implies a “working and resting rhythm” in the biosynthesis of cellulose. CNWs are highly dispersible in water and polar organic solvents, and are much easier to combine with other classes of polymers at nano-levels. The findings can enhance the feasibility and applicability of native cellulose to achieve sustainable development goals.

An X-ray diffraction system with controlled relative humidity and temperature

1996 ◽  
Vol 11 (4) ◽  
pp. 288-289 ◽  
Author(s):  
H. Hashizume ◽  
S. Shimomura ◽  
H. Yamada ◽  
T. Fujita ◽  
H. Nakazawa ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Control Unit ◽  
Saturated Water Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Saturated Water ◽  
Sample Chamber ◽  
Diffraction Patterns ◽  
Xrd Patterns

A system enabling X-ray diffraction patterns under controlled conditions of relative humidity and temperature has been devised and combined with an X-ray powder diffractometer. Relative humidity in the sample space is controlled by mixing dry N2 gas with saturated water vapor. Temperatures of the sample and inner wall of the sample chamber are monitored by two attached thermocouples and the information was fed back to the control unit. Relative humidity between 0% and the 95%, and temperature between room temperature and 60 °C can be controlled. All parameters including those for XRD are programmable and the system runs automatically. The function of the system was checked by recording the XRD patterns of montmorillonite (a clay mineral) and NaCl under increasing and decreasing relative humidity.

Generation of aerosol and droplets in binary mixtures of saturated water vapor with air and molecular gases

2016 ◽  
Vol 29 (2) ◽  
pp. 127-134 ◽  
Author(s):  
A. V. Klimkin ◽  
A. N. Kuryak ◽  
Yu. N. Ponomarev ◽  
A. S. Kozlov ◽  
S. B. Malyshkin ◽  
...  
Keyword(s):  
Water Vapor ◽  
Binary Mixtures ◽  
Saturated Water Vapor ◽  
Molecular Gases ◽  
Saturated Water

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

The effect of silver concentration and calcination temperature on structural and optical properties of ZnO:Ag nanoparticles

2015 ◽  
Vol 29 (01) ◽  
pp. 1450254 ◽  
Author(s):  
M. Shayani Rad ◽  
A. Kompany ◽  
A. Khorsand Zak ◽  
M. E. Abrishami
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Visible Emission ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Zno Nps ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Average Size

Pure and silver added zinc oxide nanoparticles ( ZnO -NPs and ZnO : Ag -NPs) were synthesized through a modified sol–gel method. The prepared samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In the XRD patterns, silver diffracted peaks were also observed for the samples synthesized at different calcination temperatures of 500°C, 700°C, 900°C except 1100°C, in addition to ZnO . TEM images indicated that the average size of ZnO : Ag -NPs increases with the amount of Ag concentration. The PL spectra of the samples revealed that the increase of Ag concentration results in the increase of the visible emission intensity, whereas by increasing the calcination temperature the intensity of visible emission of the samples decreases.

Pyrolytic Deposition of MnO2 Layers in Saturated Water Vapor Atmospheres

1980 ◽  
Vol 127 (10) ◽  
pp. 2180-2181 ◽  
Author(s):  
J. M. Albella ◽  
L. Fernández‐Navarrete ◽  
J. M. Martínez‐Duart
Keyword(s):  
Water Vapor ◽  
Saturated Water Vapor ◽  
Saturated Water
Sign in / Sign up

Export Citation Format

Share Document