Characterization of the photocurrents generated by the laser of atomic force microscopes

2016 ◽  
Vol 87 (8) ◽  
pp. 083703 ◽  
Author(s):  
Yanfeng Ji ◽  
Fei Hui ◽  
Yuanyuan Shi ◽  
Vanessa Iglesias ◽  
David Lewis ◽  
...  
Keyword(s):  
Atomic Force Microscopes ◽  
Atomic Force

Characterization of a β-Glucan Particle Using the Scanning Tunneling and Atomic Force Microscopes

1992 ◽  
pp. 131-144
Author(s):  
Antonio A. Garcia ◽  
Patrick Oden ◽  
Uwe Knipping ◽  
Gary Ostroff ◽  
Roberta Druyor
Keyword(s):  
Scanning Tunneling ◽  
Atomic Force Microscopes ◽  
Atomic Force

scholarly journals A Crowdsourcing-based Air Pollution Measurement System Using DIY Atomic Force Microscopes

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Daniel Lopez Martinez ◽  
Daniel Lombraña ◽  
Francois Grey ◽  
En-te Hwu
Keyword(s):  
Air Pollution ◽  
Measurement System ◽  
Human Computation ◽  
Global Pattern ◽  
Atomic Force Microscopes ◽  
Atomic Force ◽  
Production And Consumption ◽  
Pollution Measurement ◽  
Scientific Platform

Air pollutants have become the major problem of many cities, causing millions of human deaths worldwide every year. Among all the noxious pollutants in air, particles with a diameter of 2.5 micrometers or less (PM2.5) are the most hazardous because they are small enough to penetrate to the lungs and invade the smallest airways. Since the presence of dangerous levels of PM2.5, commonly reported in newspapers and on TV, is intertwined with the global pattern of production and consumption, there is a need for citizen science projects that engage the young generations in efforts toward reducing air pollution as they will become the future leaders of society. With this goal, and to enable the geo-temporal characterization of PM2.5, we present a crowdsourcing-based air pollution measurement system that uses affordable DIY atomic force microscopes to measure and characterize PM2.5, exploiting the power of human computation through an online crowdsourcing platform to study how PM2.5 varies over time and across geographical locations. Our system is intended as both a scientific platform and a teaching tool for children to engage in environmental policy. 

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

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.

Case Studies in Atomic Force Probe Analysis

2006 ◽  
Author(s):  
Randal Mulder ◽  
Sam Subramanian ◽  
Tony Chrastecky
Keyword(s):  
Failure Analysis ◽  
Case Studies ◽  
Light Emission ◽  
Electrical Characterization ◽  
Logic Circuits ◽  
Contrast Imaging ◽  
Atomic Force ◽  
Measuring Surface ◽  
Analysis Environment

Abstract The use of atomic force probe (AFP) analysis in the analysis of semiconductor devices is expanding from its initial purpose of solely characterizing CMOS transistors at the contact level with a parametric analyzer. Other uses found for the AFP include the full electrical characterization of failing SRAM bit cells, current contrast imaging of SOI transistors, measuring surface roughness, the probing of metallization layers to measure leakages, and use with other tools, such as light emission, to quickly localize and identify defects in logic circuits. This paper presents several case studies in regards to these activities and their results. These case studies demonstrate the versatility of the AFP. The needs and demands of the failure analysis environment have quickly expanded its use. These expanded capabilities make the AFP more valuable for the failure analysis community.

Atomic force acoustic microscopy characterization of carbon-based materials

2007 ◽  
Author(s):  
D. Passeri ◽  
A. Bettucci ◽  
M. Germano ◽  
A. Biagioni ◽  
M. Rossi ◽  
...  
Keyword(s):  
Acoustic Microscopy ◽  
Atomic Force ◽  
Microscopy Characterization ◽  
Carbon Based

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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