scholarly journals Comparison of Treatments by Mercerization and Plasma Glow Discharge on Residues of the Amazon Chestnut Shell (Bertholletia Excelsa)

2021 ◽  
Vol 42 (1) ◽  
pp. e86698
Author(s):  
Ximena Zapata Londoño ◽  
James Janderson Rosero Romo ◽  
Hugo Armando Estupiñan Duran
Keyword(s):  
Glow Discharge ◽  
Glow Discharge Plasma ◽  
Walnut Shell ◽  
Crystalline Cellulose ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chestnut Shell ◽  
Naoh Solution ◽  
Microscopy Techniques

The chestnut shell from the Amazon region shared between Colombia, Brazil, and Perú is an abundant residue of the walnut used for obtaining food and cosmetic products. This residue is not yet usable due to the lack of knowledge of its properties and the environmental impact generated by its treatment through methods such as mercerization. This work presents the results of the characterization of Amazon chestnut shell residues treated by two methods, mercerization with NaOH solution and intense plasma discharge (Glow Discharge Plasma), in a reactor with argon gas in a 0,3-bar vacuum and discharge conditions of 80 mA and 600 s. The microstructural, morphological, topographic, and nanomechanical changes of the chestnut residues without treatment and with the two proposed treatments were evaluated by means of the µRaman, scanning electron microscopy, and atomic force microscopy techniques. The results showed the effectiveness of the plasma method over the mercerization method at obtaining more crystalline cellulose structures due to the reduction of hemicellulose, lignin, and the aqueous phase of walnut shell waste.

Advances in microscopy of polymers: A FESEM and STM study

1991 ◽  
Vol 49 ◽  
pp. 1042-1043
Author(s):  
R.T. Chen ◽  
M.G. Jamieson
Keyword(s):  
Field Emission ◽  
Liquid Crystalline ◽  
Low Voltage ◽  
Polymeric Materials ◽  
Crystalline Polymer ◽  
Scanning Tunneling ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Techniques

Microscopy has played a major role in establishing structure-process-property relationships in the research and development of polymeric materials. With advances in electron microscopy instrumentation (e.g., field emission SEM - FESEM) and the invention of new scanning probe microscopes (e.g., scanning tunneling microscope - STM), resolution of structures or morphologies down to the nanometer scale can be achieved with ease. This paper will focus on the application of FESEM and STM in order to understand the structure of commercial polymeric materials. Characterization of polymers using other microscopy techniques such as TEM, thermal optical microscopy and atomic force microscopy (AFM) will also be discussed.The polymeric materials evaluated in this study include membranes, liquid crystalline polymer (LCP) fibers, multiphase polymer blends and polymer films or coatings. In order to minimize beam damage and maximize contrast for surface detail in beam sensitive polymers, low voltage SEM (LVSEM) was performed on a JEOL 840F field emission SEM.

scholarly journals In situ characterization of nanoscale contaminations adsorbed in air using atomic force microscopy

2018 ◽  
Vol 9 ◽  
pp. 2925-2935 ◽  
Author(s):  
Jesús S Lacasa ◽  
Lisa Almonte ◽  
Jaime Colchero
Keyword(s):  
Atomic Force Microscopy ◽  
Ambient Conditions ◽  
Contact Potential ◽  
Force Microscopy ◽  
Multidimensional Spectroscopy ◽  
Atomic Force ◽  
Microscopy Techniques ◽  
Sample System

Under ambient conditions, surfaces are rapidly modified and contaminated by absorbance of molecules and a variety of nanoparticles that drastically change their chemical and physical properties. The atomic force microscope tip–sample system can be considered a model system for investigating a variety of nanoscale phenomena. In the present work we use atomic force microscopy to directly image nanoscale contamination on surfaces, and to characterize this contamination by using multidimensional spectroscopy techniques. By acquisition of spectroscopy data as a function of tip–sample voltage and tip–sample distance, we are able to determine the contact potential, the Hamaker constant and the effective thickness of the dielectric layer within the tip–sample system. All these properties depend strongly on the contamination within the tip–sample system. We propose to access the state of contamination of real surfaces under ambient conditions using advanced atomic force microscopy techniques.

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

2019 ◽  
Author(s):  
Priya Prakash ◽  
Travis Lantz ◽  
Krupal P. Jethava ◽  
Gaurav Chopra
Keyword(s):  
Amyloid Beta ◽  
Western Blots ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Set Up ◽  
Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

Stereometric characterization of Dinizia excelsa Ducke wood from Amazon rainforest using atomic force microscopy

2021 ◽  
Author(s):  
Willian Silva Conceição ◽  
Ştefan Ţălu ◽  
Robert Saraiva Matos ◽  
Glenda Quaresma Ramos ◽  
Fidel Guereiro Zayas ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Amazon Rainforest ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dinizia Excelsa

scholarly journals A Universal Model for the Log-Normal Distribution of Elasticity in Polymeric Gels and Its Relevance to Mechanical Signature of Biological Tissues

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 64
Author(s):  
Arnaud Millet
Keyword(s):  
Elastic Modulus ◽  
Normal Distribution ◽  
Biological Tissues ◽  
Force Microscopy ◽  
Polymeric Gels ◽  
Atomic Force ◽  
Clear Explanation ◽  
Log Normal ◽  
Log Normal Distribution

The mechanosensitivity of cells has recently been identified as a process that could greatly influence a cell’s fate. To understand the interaction between cells and their surrounding extracellular matrix, the characterization of the mechanical properties of natural polymeric gels is needed. Atomic force microscopy (AFM) is one of the leading tools used to characterize mechanically biological tissues. It appears that the elasticity (elastic modulus) values obtained by AFM presents a log-normal distribution. Despite its ubiquity, the log-normal distribution concerning the elastic modulus of biological tissues does not have a clear explanation. In this paper, we propose a physical mechanism based on the weak universality of critical exponents in the percolation process leading to gelation. Following this, we discuss the relevance of this model for mechanical signatures of biological tissues.

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