Paper Making Furnish as a Composite Blend. Some Wet End Interactions among Furnish Ingredients

1990 ◽  
Vol 197 ◽  
Author(s):  
Joseph Marton
Keyword(s):  
Strength Loss ◽  
Accessible Surface Area ◽  
Strength Properties ◽  
Fiber Network ◽  
Cellulosic Fibers ◽  
Paper Making ◽  
Fibrous Network ◽  
Retention Aids ◽  
Accessible Surface ◽  
End Use

ABSTRACTC.A. Hogart defined paper as “a random bonded fibrous network carrying filler material“. A few thoughts related to this definition and pertaining to paper composites are presented.A typical papermaking furnish consists of a blend of cellulosic fibers and fines, inorganic fillers and additives. Composition varies according to end use requirements. The fiber network secures desired mechanical and strength properties, fillers contribute to esthetics and good optics. Filler retention is improved by using retention aids. Strength-loss due to filler, use is compensated for, by applying strength additives.Additives applied at the wet end interact with furnish components. The surface charge, accessible surface area and composition play a role in the interactions. Some typical interactions, involving cationic starch and polyacrylamide, are discussed.

Study of Culture Paper Making with P-RC APMP by Different Papermaking Process

2012 ◽  
Vol 629 ◽  
pp. 347-351
Author(s):  
Tao Lin ◽  
Jian Wei Song ◽  
Xue Feng Yin ◽  
Zhi Jie Wang
Keyword(s):  
Calcium Carbonate ◽  
Raw Materials ◽  
Strength Properties ◽  
Precipitated Calcium Carbonate ◽  
Sem Images ◽  
Paper Properties ◽  
Fiber Network ◽  
Paper Making ◽  
Flocculation Process ◽  
Ground Calcium Carbonate

Using Poplar P-RC APMP as raw materials for culture paper making, the effect of conventional papermaking process and P-RC APMP fines-calcium carbonate co-flocculation process on the P-RC APMP culture paper properties were studied. The result showed that, comparing to the conventional papermaking process, co-flocculation process can supply paper with better strength properties, bulk and whiteness. When precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC) were added respectively in conventional papermaking process, the PCC supplied handsheets with better bulk and whiteness, while GCC supplied handsheets with better strength properties. In the co-flocculation process, the effects of PCC and GCC were nearly the same in strength properties and bulk of handsheets, but PCC was more beneficial for whiteness. SEM images showed that PCC distributed more evenly in the fiber network, and well-bonded with fiber network. The particle size of GCC is relatively small, mainly filled in the fiber network and wrapped on the fiber.

Does kraft hardwood and softwood pulp viscosity correlate to paper properties?

TAPPI Journal ◽  
2016 ◽  
Vol 15 (10) ◽  
pp. 643-651 ◽  
Author(s):  
ROBERT J. OGLESBY ◽  
HUMPHREY J. MOYNIHAN ◽  
RICARDO B. SANTOS ◽  
ASHOK GHOSH ◽  
PETER W. HART
Keyword(s):  
Physical Properties ◽  
Strength Loss ◽  
Strength Properties ◽  
Clear Correlation ◽  
Paper Properties ◽  
Physical Strength ◽  
Pulp Viscosity ◽  
Softwood Pulp ◽  
The Impact ◽  
Related Paper

The impact of commercially prepared, fully bleached pulp viscosity variation on handsheet physical properties was evaluated at different levels of pulp refining. Hardwood pulps from the same brownstock species mix, cooking parameters, and kappa numbers were processed through two different commercial bleach plants: one with a D0(EP)D1D2 sequence and the second with an OD0(EOP)D1 sequence. Additionally, a commercial softwood (predominately Scotts pine) brownstock pulp bleached by an OD0(EP)D1D2 sequence was employed in this study. Pulps with viscosities ranging from 14 to 21 mPa∙s were refined in a Valley beater to two freeness levels, and the associated handsheet physical properties were measured in this study. Over the pulp viscosity range of 14 to 21 mPa∙s, no clear correlation was found to exist between pulp viscosity and related paper physical properties. Finally, a series of laboratory prepared bleached pulps were purposely prepared under non-ideal conditions to reduce their final viscosities to lower values. Handsheets made from these pulps were tested in their unbeaten condition for physical strength properties. Significant and rapid strength loss occurred when the measured pulp viscosity dropped below 12 mPa∙s; overall strength properties showed no correlation to viscosity above the critical 12 mPa∙s value.

Application of the ESMACS Binding Free Energy Protocol to a Highly Varied Ligand Dataset: Lactate Dehydogenase A

2019 ◽  
Author(s):  
David Wright ◽  
Fouad Husseini ◽  
Shunzhou Wan ◽  
Christophe Meyer ◽  
Herman Van Vlijmen ◽  
...  
Keyword(s):  
Free Energy ◽  
Surface Area ◽  
Binding Free Energy ◽  
Normal Mode Analysis ◽  
Binding Mode ◽  
Accessible Surface Area ◽  
Solvent Accessible Surface Area ◽  
Mode Analysis ◽  
Energy Calculation ◽  
Accessible Surface

<div>Here, we evaluate the performance of our range of ensemble simulation based binding free energy calculation protocols, called ESMACS (enhanced sampling of molecular dynamics with approximation of continuum solvent) for use in fragment based drug design scenarios. ESMACS is designed to generate reproducible binding affinity predictions from the widely used molecular mechanics Poisson-Boltzmann surface area (MMPBSA) approach. We study ligands designed to target two binding pockets in the lactate dehydogenase A target protein, which vary in size, charge and binding mode. When comparing to experimental results, we obtain excellent statistical rankings across this highly diverse set of ligands. In addition, we investigate three approaches to account for entropic contributions not captured by standard MMPBSA calculations: (1) normal mode analysis, (2) weighted solvent accessible surface area (WSAS) and (3) variational entropy. </div>

scholarly journals An automated protocol for modelling peptide substrates to proteases

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Rodrigo Ochoa ◽  
Mikhail Magnitov ◽  
Roman A. Laskowski ◽  
Pilar Cossio ◽  
Janet M. Thornton
Keyword(s):  
Substrate Recognition ◽  
Accessible Surface Area ◽  
Conformational Sampling ◽  
Structural Determinants ◽  
Peptide Substrates ◽  
The Family ◽  
Protease Substrate ◽  
Peptide Complexes ◽  
Accessible Surface ◽  
Automated Protocol

Abstract Background Proteases are key drivers in many biological processes, in part due to their specificity towards their substrates. However, depending on the family and molecular function, they can also display substrate promiscuity which can also be essential. Databases compiling specificity matrices derived from experimental assays have provided valuable insights into protease substrate recognition. Despite this, there are still gaps in our knowledge of the structural determinants. Here, we compile a set of protease crystal structures with bound peptide-like ligands to create a protocol for modelling substrates bound to protease structures, and for studying observables associated to the binding recognition. Results As an application, we modelled a subset of protease–peptide complexes for which experimental cleavage data are available to compare with informational entropies obtained from protease–specificity matrices. The modelled complexes were subjected to conformational sampling using the Backrub method in Rosetta, and multiple observables from the simulations were calculated and compared per peptide position. We found that some of the calculated structural observables, such as the relative accessible surface area and the interaction energy, can help characterize a protease’s substrate recognition, giving insights for the potential prediction of novel substrates by combining additional approaches. Conclusion Overall, our approach provides a repository of protease structures with annotated data, and an open source computational protocol to reproduce the modelling and dynamic analysis of the protease–peptide complexes.

scholarly journals PAMAM dendrimer: a pH-controlled nanosponge

2017 ◽  
Vol 95 (9) ◽  
pp. 991-998 ◽  
Author(s):  
Prabal K. Maiti
Keyword(s):  
Accessible Surface Area ◽  
Pamam Dendrimer ◽  
Low Ph ◽  
Dynamics Simulation ◽  
Solvent Accessible Surface Area ◽  
Water Molecules ◽  
Accessible Volume ◽  
Accessible Surface ◽  
Solvent Accessible Surface ◽  
Ph Controlled

Using fully atomistic molecular dynamics simulation that are several hundred nanoseconds long, we demonstrate the pH-controlled sponge action of PAMAM dendrimer. We show how at varying pH levels, the PAMAM dendrimer acts as a wet sponge; at neutral or low pH levels, the dendrimer expands noticeably and the interior of the dendrimer opens up to host several hundreds to thousands of water molecules depending on the generation number. Increasing the pH (i.e., going from low pH to high pH) leads to the collapse of the dendrimer size, thereby expelling the inner water, which mimics the ‘sponge’ action. As the dendrimer size swells up at a neutral pH or low pH due to the electrostatic repulsion between the primary and tertiary amines that are protonated at this pH, there is dramatic increase in the available solvent accessible surface area (SASA), as well as solvent accessible volume (SAV).

PUTRACER: A NOVEL METHOD FOR IDENTIFICATION OF CONTINUOUS-DOMAINS IN MULTI-DOMAIN PROTEINS

2013 ◽  
Vol 11 (01) ◽  
pp. 1340012 ◽  
Author(s):  
SEYED SHAHRIAR ARAB ◽  
MOHAMMADBAGHER PARSA GHARAMALEKI ◽  
ZAIDDODINE PASHANDI ◽  
REZVAN MOBASSERI
Keyword(s):  
Protein Structures ◽  
Three Dimensional ◽  
Accessible Surface Area ◽  
Computer Assisted ◽  
Correct Assignment ◽  
Critical Boundary ◽  
Novel Method ◽  
Accessible Surface ◽  
A Chain

Computer assisted assignment of protein domains is considered as an important issue in structural bioinformatics. The exponential increase in the number of known three dimensional protein structures and the significant role of proteins in biology, medicine and pharmacology illustrate the necessity of a reliable method to automatically detect structural domains as protein units. For this aim, we have developed a program based on the accessible surface area (ASA) and the hydrogen bonds energy in protein backbone (HBE). PUTracer (Protein Unit Tracer) is built on the features of a fast top-down approach to cut a chain into its domains (contiguous domains) with minimal change in ASA as well as HBE. Performance of the program was assessed by a comprehensive benchmark dataset of 124 protein chains, which is based on agreement among experts (e.g. CATH, SCOP) and was expanded to include structures with different types of domain combinations. Equal number of domains and at least 90% agreement in critical boundary accuracy were considered as correct assignment conditions. PUTracer assigned domains correctly in 81.45% of protein chains. Although low critical boundary accuracy in 18.55% of protein chains leads to the incorrect assignments, adjusting the scales causes to improve the performance up to 89.5%. We discuss here the success or failure of adjusting the scales with provided evidences. Availability: PUTracer is available at http://bioinf.modares.ac.ir/software/PUTracer/

Sign in / Sign up

Export Citation Format

Share Document