First characterization of the development of bleached kraft softwood pulp fiber interfaces during drying and rewetting using FRET microscopy

Holzforschung ◽  
2008 ◽  
Vol 62 (4) ◽  
Author(s):  
Cameron I. Thomson ◽  
Robert M. Lowe ◽  
Arthur J. Ragauskas
Keyword(s):  
Kraft Pulp ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Pulp Fiber ◽  
Cellulosic Fibers ◽  
Bleached Kraft Pulp ◽  
Microscopy Technique ◽  
Wet Pressing ◽  
Fiber Components ◽  
Solids Content

Abstract Cellulosic fiber interfaces are critical to the material properties of paper. Likewise, the presence of water in a paper sheet is an important property, because paper is a wet-laid structure and the cellulosic fibers that compose it are hygroscopic. This work uses a fluorescence microscopy technique established by the authors to study the development of individual bleached kraft pulp fiber crossings in situ during drying and through a cycle of rewetting and wet pressing. The results indicate that coalescence of the fiber-fiber interface occurs during drying and that the fluorescence resonance energy transfer (FRET) response, which is proportional to the distance between fiber components, increases logarithmically with time. The FRET signal of once-dried fiber crossings increases dramatically after rewetting and wet pressing for a second time. This indicates that fiber bonds are still compliant after a single drying cycle and that the interactions between fiber components are likely reversible at the solids content present in bleached kraft pulp fiber crossings dried at 25°C and 50% relative humidity.

Action Mechanism of the Improvement of Printability for Eucalypt Bleached Kraft Pulp Pretreated by Cellulase

2013 ◽  
Vol 779-780 ◽  
pp. 294-301
Author(s):  
Wan You Tang ◽  
Li Chen ◽  
Zheng Jian Zhang
Keyword(s):  
Tensile Strength ◽  
Fiber Length ◽  
Kraft Pulp ◽  
Pulp Fiber ◽  
Fiber Morphology ◽  
Strength Index ◽  
Bleached Kraft Pulp ◽  
Tear Index ◽  
Pulp Sample ◽  
The Mean

Enzymatic refining of eucalypt bleached kraft pulp with the cellulase NOV476 was studied. The effects of this cellulase on the physical properties of pulp, fiber morphology and fiber appearance of the eucalypt bleached kraft pulp in different application conditions were discussed. The results show that, with the increase in the amount of enzyme, tensile strength index, burst index and TEA index of paper are increased and then decreased; elongation and tear index of paper have been declining, Zeeil tensile strength index has been an upward trend. Without beating the pulp sample, gradually increases as the amount of enzyme, the average fiber length and the average fiber width are gradually reduced, while mean kink index substantially constant. Number of vessels in fiber overall reduced tendency reaches a minimum in the amount of enzyme 0.5μ/g, the phenomenon is most obvious. In the same conditions of beating time, gradually increases as the amount of enzyme, the average fiber length is gradually reduced, an average fiber width is gradually increased, the mean kink index reaches a maximum in the amount of enzyme is 0.5μ/g. Number of vessels in fiber overall reduced trend.

Fold cracking of coated paper: The effect of pulp fiber composition and beating

2012 ◽  
Vol 27 (2) ◽  
pp. 445-450 ◽  
Author(s):  
Hye Jung Youn ◽  
Kyujeong Sim ◽  
Kyu Deok Oh ◽  
Hak Lae Lee ◽  
Chang Sun Han ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Kraft Pulp ◽  
Low Cost ◽  
Pulp Fiber ◽  
Mixing Ratio ◽  
Pulp Fibers ◽  
Coated Paper ◽  
Mixing Ratios ◽  
Bleached Kraft Pulp ◽  
Base Paper

Abstract Fold cracking of coated papers has become important because of the increase in the coat weight and the content of low cost co-binder. The effects of base paper characteristics of coated paper were investigated to reduce fold cracking. We evaluated the fold cracking of coated paper prepared with different mixing ratios and beating degrees of pulp fibers. Hardwood bleached kraft pulp (Hw-BKP) and softwood bleached kraft pulp (Sw- BKP) were used to prepare base papers for coating. The mechanical and structural properties of base paper such as tensile strength, strain at break, short span compressive strength, and formation were measured. The fold cracking was affected by mixing ratio of pulp fibers. Base paper consisting of Hw-BKP and Sw-BKP at a 90:10 mixing ratio showed the least fold cracking. When the amount of Sw-BKP was greater than 10% or if only Hw- BKP was used, the fold cracking increased on coated paper. When the pulp was highly beaten, the mechanical strength of paper was improved, but the fold cracking was severe. An increase in the tensile strength did not reduce the fold cracking.

Effect of ultraviolet irradiation on the thermal stability of bleached eucalyptus kraft pulp

TAPPI Journal ◽  
2012 ◽  
Vol 11 (2) ◽  
pp. 69-74
Author(s):  
VAGNER ROBERTO BOTARO ◽  
KÁTIA MONTEIRO NOVACK ◽  
JORGE LUIZ COLODETTE ◽  
LEONARDO SOUZA DE CAUX
Keyword(s):  
Thermal Stability ◽  
Ultraviolet Irradiation ◽  
Kraft Pulp ◽  
Cellulose Oxidation ◽  
Cellulosic Fibers ◽  
Bleached Kraft Pulp ◽  
Elemental Chlorine ◽  
Eucalyptus Kraft Pulp ◽  
Pulp Sample ◽  
Ultraviolet Treatment

The changes occurring on cellulosic fibers caused by ultraviolet irradiation at 360 nm for 24 h and 48 h were investigated. A never-dried industrial Eucalyptus urograndis elemental chlorine free–bleached kraft pulp sample (O/OD[EP]DP sequence) was used throughout the work. After irradiation, the cellulosic fibers were analyzed for polymerization degree changes, extractive and pentosan content, ultraviolet and visible spectrometric changes of water leachate from the fibers and thermal analysis (TGA/DTA). The ultraviolet treatment had no effect on the degree of cellulose polymerization. The water extracted from ultraviolet-treated fibers revealed cellulose oxidation, with increasing absorbance signals for carbonyl and carboxyl groups. Those oxidations influenced fiber thermal stability.

Significant contribution of fibrils on pulp fiber surface to water retention value

2020 ◽  
Vol 35 (1) ◽  
pp. 96-105
Author(s):  
Minoru Kimura ◽  
Takashi Ishida ◽  
Yuko Ono ◽  
Miyuki Takeuchi ◽  
Akira Isogai
Keyword(s):  
Cell Walls ◽  
Kraft Pulp ◽  
Water Retention ◽  
Structural Changes ◽  
Significant Contribution ◽  
Fiber Surface ◽  
Pulp Fiber ◽  
Pulp Fibers ◽  
Bleached Kraft Pulp ◽  
Two Factors

AbstractThe contribution of structural changes of softwood bleached kraft pulp (SBKP) fibers and partly dried SBKP handsheets to their water retention values (WRVs) was studied. Two factors related to mesopores and macropores, which were determined for super critical point (SCP)-dried SBKP sheet samples, should participate in the WRVs determined for wet SBKP sheet samples. The mesopores are formed during pulping/bleaching to remove lignin and a part of hemicelluloses that are present originally in wood cell walls. The combined volumes of mesopores and macropores (totally < ∼0.6 g g−1) in SBKP fibers after SCP drying were significantly lower than the entire WRV (∼1.6 g g−1) of the original never-dried SBKP. We hypothesize that external fibrils of SBKP fibers are formed during pulping, bleaching, washing, pressure-screening, and pressing processes at high and low solid contents in water under high shear forces. The WRV can be used as an indicator to evaluate such structural changes of external fibrils in pulp fibers and paper sheets during drying/wetting in papermaking process as well as in use under various conditions. In contrast, changes in mesopore and macropore volumes determined for SCP-dried sheets cannot properly detect such structural changes of external fibrils.

Laser-Excited One-Atom Source of Electrons

1997 ◽  
Vol 06 (04) ◽  
pp. 411-420
Author(s):  
V. S. Letokhov ◽  
S. K. Sekatskii
Keyword(s):  
Calcium Fluoride ◽  
Lithium Fluoride ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Fluorescence Yield ◽  
Color Centers ◽  
Light Sources ◽  
Microscopy Technique ◽  
Atom Source ◽  
High Fluorescence

A finite number of color centers in the region of sharp crystal needle's tip has been recently observed by laser resonance photoelectron projection microscopy technique. Hereby we present a new result in the field: only one single color center was observed on the tip region of lithium fluoride and calcium fluoride needles. Due to the high fluorescence yield of these color centers such needles can be treated as one-atom light sources, and perspectives of their application in Scanning One-Atom Fluorescence Resonance Energy Transfer Microscopy are briefly discussed.

Structural dynamics of P-type ATPase ion pumps

2019 ◽  
Vol 47 (5) ◽  
pp. 1247-1257 ◽  
Author(s):  
Mateusz Dyla ◽  
Sara Basse Hansen ◽  
Poul Nissen ◽  
Magnus Kjaergaard
Keyword(s):  
Structural Dynamics ◽  
Single Molecule ◽  
New Technologies ◽  
Atp Hydrolysis ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Time Resolved ◽  
Dynamics Simulations ◽  
Types Of Information ◽  
P Type

Abstract P-type ATPases transport ions across biological membranes against concentration gradients and are essential for all cells. They use the energy from ATP hydrolysis to propel large intramolecular movements, which drive vectorial transport of ions. Tight coordination of the motions of the pump is required to couple the two spatially distant processes of ion binding and ATP hydrolysis. Here, we review our current understanding of the structural dynamics of P-type ATPases, focusing primarily on Ca2+ pumps. We integrate different types of information that report on structural dynamics, primarily time-resolved fluorescence experiments including single-molecule Förster resonance energy transfer and molecular dynamics simulations, and interpret them in the framework provided by the numerous crystal structures of sarco/endoplasmic reticulum Ca2+-ATPase. We discuss the challenges in characterizing the dynamics of membrane pumps, and the likely impact of new technologies on the field.

Quantum Dot Bioconjugates as Energy Donors in Fluorescence Resonance Energy Transfer Assays

2003 ◽  
Vol 773 ◽  
Author(s):  
Aaron R. Clapp ◽  
Igor L. Medintz ◽  
J. Matthew Mauro ◽  
Hedi Mattoussi
Keyword(s):  
Energy Transfer ◽  
Quantum Dot ◽  
Organic Dyes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Genetically Engineered ◽  
Molar Ratio ◽  
Binding Assays ◽  
Specific Sequence ◽  
Donor Acceptor

AbstractLuminescent CdSe-ZnS core-shell quantum dot (QD) bioconjugates were used as energy donors in fluorescent resonance energy transfer (FRET) binding assays. The QDs were coated with saturating amounts of genetically engineered maltose binding protein (MBP) using a noncovalent immobilization process, and Cy3 organic dyes covalently attached at a specific sequence to MBP were used as energy acceptor molecules. Energy transfer efficiency was measured as a function of the MBP-Cy3/QD molar ratio for two different donor fluorescence emissions (different QD core sizes). Apparent donor-acceptor distances were determined from these FRET studies, and the measured distances are consistent with QD-protein conjugate dimensions previously determined from structural studies.

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