scholarly journals Micro/nano-structural evolution in spruce wood during soda pulping

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ahmed Wagih ◽  
Merima Hasani ◽  
Stephen A. Hall ◽  
Hans Theliander
Keyword(s):  
Large Scale ◽  
Structural Information ◽  
Early Stage ◽  
Morphological Changes ◽  
Structural Evolution ◽  
Wood Tissue ◽  
X Ray ◽  
Alkaline Pulping ◽  
Soda Pulping ◽  
Alkaline Delignification

Abstract Alkaline delignification of wood tissue is the core of the global pulping technology and the most prominent large-scale separation of the main wood components. This work aims at improved understanding of the interplay between the topochemistry of alkaline pulping and the associated morphological changes. Morphology and chemical structure of partially soda-delignified wood chips were studied combining X-ray tomography (XRT), X-ray diffraction analysis and compositional characterization (lignin and carbohydrate content). The XRT studies of wet samples (providing 3D structural information without interfering drying effects), allowed observation of the cell wall separation as an increasing amount of lignin was removed with the increasing pulping time. Comparison between the microstructure of the surface and the central parts of the treated chips showed a more delignified microstructure at the surface, which highlights the dependence of the delignification process on the mass transport (hydroxide ions and lignin fragments) through the wood tissue. The crystallite size of cellulose increased in the <200> crystal planes during the early stage of pulping while there was little effect on the <110> plane.

Structural Investigation of a Surfactant-Templated Silica Aerogel by Small-angle Scattering

1998 ◽  
Vol 520 ◽  
Author(s):  
Thomas P. Riekerlt ◽  
Mark T. Anderson ◽  
Patricia S. Sawyer ◽  
Shrish Rane ◽  
Gregory Beaucage
Keyword(s):  
Light Scattering ◽  
Small Angle ◽  
Silica Aerogel ◽  
Large Scale ◽  
Structural Investigation ◽  
Structural Information ◽  
Structural Features ◽  
Length Scales ◽  
X Ray ◽  
Angle Scattering

ABSTRACTThe structure of a surfactant-templated silica aerogel is studied by small-angle x-ray and light scattering. By combining the two techniques, we obtain structural information on length scales from Ångstroms to 0.1 millimeters. For this sample, we find five structural features, including the morphology of large scale aggregates.

scholarly journals Reciprocal Space Analysis of the Initial Stages of Strain Relaxation in SiGe Epilayers

1995 ◽  
Vol 399 ◽  
Author(s):  
S. R. Lee ◽  
J. A. Floro
Keyword(s):  
Early Stage ◽  
Strain Relaxation ◽  
Geometric Model ◽  
Structural Evolution ◽  
Reciprocal Space ◽  
Displacement Fields ◽  
Diffuse Intensity ◽  
X Ray ◽  
Space Analysis ◽  
Dislocation Array

ABSTRACTMetastable SiGe films were grown by MBE on Si (001) substrates and annealed to promote varying degrees of partial relaxation. X-ray diffraction reciprocal-space analysis was then used to monitor the structural evolution of the displacement fields of the dislocation array with increasing misfit density. The diffuse-x-ray-scattering patterns of the dislocated heterolayers were compared with lineal-misfit densities determined by defect etching, leading us to develop a geometric model which provides a framework for understanding the early-stage evolution of the displacement fields of the dislocation array, and which also explicitly links diffuse x-ray intensity to misfit density. At low misfit density, the diffuse intensity arises from two-dimensional displacement fields associated with single-nonoverlapping dislocations. As misfit density increases, the displacement fields of individual dislocations increasingly overlap producing three-dimensional displacements. The evolving diffuse intensity reflects the transition from 2-D to 3-D displacement fields. Finally, it is demonstrated that the diffuse x-ray intensity of the strained epilayer can be used to accurately measure lineal misfit-dislocation densities from 400 to 20,000 lines/cm.

Study of the early Stage of Deposition Process for Electrodeposited Ni100-XFeX Thin Films

2011 ◽  
Vol 495 ◽  
pp. 1-4 ◽  
Author(s):  
Saci Messaadi ◽  
Mosbah Daamouche ◽  
Abderrahim Guittoum ◽  
Hadria Medouer ◽  
Noureddine Fenineche ◽  
...  
Keyword(s):  
Experimental Data ◽  
Electrochemical Method ◽  
Early Stage ◽  
Structural Evolution ◽  
Deposition Process ◽  
Optimal Conditions ◽  
X Ray Diffraction ◽  
Nucleation Kinetics ◽  
Theoretical Methods ◽  
X Ray

The aim of this work is to understand the early stages in the growth mechanism of invar (Fe64Ni34) alloys and also to study the influence of potential on the evolution of their crystalline structures. Fe64Ni34 layers were deposited onto copper substrates under optimal conditions using the electrochemical method of cyclic voltammetry (CV) and chronoamperometry (CA). The influence of the potential is examined and the nucleation kinetics is discussed. In this purpose, the obtained experimental data was interpreted by applying useful theoretical methods developed by Scharifker and Hills. X-ray diffraction experiments were performed on all samples in order to follow the structural evolution of Fe64Ni34 layers as a function of the potential.

scholarly journals Needleless Electrospinning of Polystyrene Fibers with an Oriented Surface Line Texture

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Chen Huang ◽  
Haitao Niu ◽  
Jinglei Wu ◽  
Qinfei Ke ◽  
Xiumei Mo ◽  
...  
Keyword(s):  
Large Scale ◽  
Early Stage ◽  
Fiber Surface ◽  
Diameter Distribution ◽  
X Ray Diffraction ◽  
Electrospinning Technique ◽  
X Ray ◽  
Needleless Electrospinning ◽  
Significant Difference ◽  
Line Texture

We have demonstrated that polystyrene (PS) nanofibers having an ordered surface line texture can be produced on a large scale from a PS solution of acetone and N,N′-dimethylformamide (2/1, vol/vol) by a needleless electrospinning technique using a disc as fiber generator. The formation of the unusual surface feature was investigated and attributed to the voids formed on the surface of jets due to the fast evaporation of acetone at the early stage of electrospinning, and subsequent elongation and solidification turning the voids into ordered lines on fiber surface. In comparison with the nanofibers electrospun by a conventional needle electrospinning using the same solution, the disc electrospun fibers were finer with similar diameter distribution. The fiber production rate for the disc electrospinning was 62 times higher than that of the conventional electrospinning. Fourier transform infrared spectroscopy and X-ray diffraction measurements indicated that the PS nanofibers produced from the two electrospinning techniques showed no significant difference in chemical component, albeit slightly higher crystallinity in the disc spun nanofibers.

Effect of Ni Addition on Formation of Nanocrystalline Phase during Mechanical Alloying of (Fe Al)-40(60) at.% Ni and (Fe Al3)-10(30) at.% Ni Powders

2013 ◽  
Vol 275-277 ◽  
pp. 1814-1817
Author(s):  
Zhang Jing ◽  
Qi Zhi Cao ◽  
Guo Hua Huang ◽  
Jin Li Huang
Keyword(s):  
Solid Solutions ◽  
Early Stage ◽  
Structural Evolution ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Powder Mixtures ◽  
X Ray ◽  
Ni Content ◽  
Ni Addition

Al-Fe-Ni ternary powder mixtures containing (FeAl)-40(60) at.% Ni and (FeAl3)-10(30) at.% Ni were mechanically alloyed by a high-energry planetary ball mill. The structural evolution of the powders during milling was studied by X-ray diffraction technique (XRD). During milling of (FeAl)-40(60) at.% Ni system, Al and Fe solid solutions formed at the early stage change to FeAl, AlNi3 and FeNi3 intermetallic compounds. However, the Al and Fe solid solutions observed at the early stage transform into Al3Ni2, AlFe3 and AlFe0.23Ni0.77 intermetallic compound at last. The experimental results showed that the last milling products were decided by the proportion of atom between Al and Fe in the powder and the Ni content in the power had not affected to the last products.

A Real-time X-ray Scattering Study of Sputtering Growth of TiN Films

1994 ◽  
Vol 375 ◽  
Author(s):  
J. H. Jel ◽  
D. Y. Noh ◽  
H. K. Kim ◽  
K. S. Liang
Keyword(s):  
Real Time ◽  
Crystallographic Orientation ◽  
Early Stage ◽  
Morphological Changes ◽  
Preferred Orientation ◽  
Tin Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Ray Scattering

AbstractWe report the results of a real-time synchrotron x-ray scattering study of the growth of TiN thin films on Si(001) substrates by RF sputtering. Our experiemnts show that the morphology of the TiN films strongly depends on growth conditions. After the nucleation and growth takes place with random crystallographic orientation at the very early stage, the films grow with a preferred orientation. Such preferred orientation was found to depend on both the sputtering power and the carrier gases used in the sputtering. Generally, the final morphology assumes either (111) or (002) crystallographic orientation. Using Ar sputtering, a cross-over effect from (002) to (111) was observed at intermediate time. The nature of the observed morphological changes is discussed.

scholarly journals Effects of Ciliate Infection on the Activities of Two Antioxidant Enzymes (SOD and CAT) in Captive Coral (Goniopora columna) and Evaluation of Drug Therapy

Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1216
Author(s):  
Chiu-Min Cheng ◽  
Yu-Rong Cheng ◽  
De-Sing Ding ◽  
Ya-Ting Chen ◽  
Wei-Ting Sun ◽  
...  
Keyword(s):  
Antioxidant Enzymes ◽  
Drug Therapy ◽  
Stress Response ◽  
Chlorophyll A ◽  
Large Scale ◽  
Early Stage ◽  
Morphological Changes ◽  
Parasitic Disease ◽  
Short Time ◽  
Selection Of

Ciliate infection is a serious parasitic disease of coral. Infected coral rots and dies in a short time. In addition to killing corals by infecting them in the oceans, ciliate infection also poses a threat to corals farmed on a large scale. In this study, two antioxidant enzymes (SOD and CAT) were used to judge the stress response in Goniopora columna after infection, and KCl and H2O2 were used to evaluate the therapeutic effect. The results showed that SOD and CAT increased during the early stage of infection but decreased with the extension of infection time. In terms of drug therapy, it was found that the treatment of ciliate infection with 1.5% of KCl had no significant effect on SOD and CAT of G. columna. The morphological changes of zooxanthellae, chlorophyll a, and coral were not significant. H2O2 leads to a stress response and polyp contraction. In conclusion, 1.5% of KCl can be used in the selection of drugs to treat ciliate infection.

scholarly journals Hydrogen atoms can be located accurately and precisely by x-ray crystallography

2016 ◽  
Vol 2 (5) ◽  
pp. e1600192 ◽  
Author(s):  
Magdalena Woińska ◽  
Simon Grabowsky ◽  
Paulina M. Dominiak ◽  
Krzysztof Woźniak ◽  
Dylan Jayatilaka
Keyword(s):  
Neutron Diffraction ◽  
Crystal Engineering ◽  
Large Scale ◽  
Materials Science ◽  
Structural Information ◽  
Inorganic Compounds ◽  
X Rays ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Bond Lengths

Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A–H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A–H bond lengths with those from neutron measurements for A–H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors.

Direct visualization of phase-separated domains in lipid membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 290-291
Author(s):  
S. W. Hui ◽  
T. P. Stewart
Keyword(s):  
Lipid Membranes ◽  
Structural Information ◽  
Freeze Fracture ◽  
Biological Molecules ◽  
Vacuum Drying ◽  
Direct Visualization ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Hydrocarbon Chains

Direct electron microscopic study of biological molecules has been hampered by such factors as radiation damage, lack of contrast and vacuum drying. In certain cases, however, the difficulties may be overcome by using redundent structural information from repeating units and by various specimen preservation methods. With bilayers of phospholipids in which both the solid and fluid phases co-exist, the ordering of the hydrocarbon chains may be utilized to form diffraction contrast images. Domains of different molecular packings may be recgnizable by placing properly chosen filters in the diffraction plane. These domains would correspond to those observed by freeze fracture, if certain distinctive undulating patterns are associated with certain molecular packing, as suggested by X-ray diffraction studies. By using an environmental stage, we were able to directly observe these domains in bilayers of mixed phospholipids at various temperatures at which their phases change from misible to inmissible states.

Pattern Formation in Thin Polymer Films: A New Morphology

2000 ◽  
Vol 629 ◽  
Author(s):  
Jean-Loup Masson ◽  
Peter F. Green
Keyword(s):  
Growth Rate ◽  
Pattern Formation ◽  
Early Stage ◽  
Structural Evolution ◽  
Distinct Form ◽  
Thin Polymer Films ◽  
Intermediate Morphology ◽  
Thin Polymer ◽  
Nonwetting Liquid ◽  
Cylindrical Holes

ABSTRACTResearchers have shown that thin, nonwetting, liquid homopolymer films dewet substrates, forming patterns that reflect fluctuations in the local film thickness. These patterns have been shown to be either discrete cylindrical holes or bicontinuous “spinodal-like” patterns. In this paper we show the existence of a new morphology. During the early stage of dewetting, discrete highly asymmetric holes appear spontaneously throughout the film. The nucleation rate of these holes is faster than their growth rate. The morphology of the late stage of evolution, after 18 days, is characterized by a bicontinuous pattern, distinct form conventional spinodal dewetting patterns. This morphology has been observed for a range of film thicknesses between 7.5 and 21nm. The structural evolution of this intermediate morphology is discussed.

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