scholarly journals Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non‐equilibrium conditions

2021 ◽  
Author(s):  
Indra J. Das ◽  
Paolo Francescon ◽  
Jean M. Moran ◽  
Anders Ahnesjö ◽  
Maria M. Aspradakis ◽  
...  
Keyword(s):  
Photon Beam ◽  
Task Group ◽  
Equilibrium Conditions ◽  
Small Fields ◽  
Beam Dosimetry ◽  
Non Equilibrium

scholarly journals A time-domain phase diagram of metastable states in a charge ordered quantum material

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jan Ravnik ◽  
Michele Diego ◽  
Yaroslav Gerasimenko ◽  
Yevhenii Vaskivskyi ◽  
Igor Vaskivskyi ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Time Domain ◽  
Metastable States ◽  
Scanning Tunneling ◽  
Photon Density ◽  
Tunneling Microscopy ◽  
Equilibrium Conditions ◽  
Time Resolved ◽  
A Charge ◽  
Non Equilibrium

AbstractMetastable self-organized electronic states in quantum materials are of fundamental importance, displaying emergent dynamical properties that may be used in new generations of sensors and memory devices. Such states are typically formed through phase transitions under non-equilibrium conditions and the final state is reached through processes that span a large range of timescales. Conventionally, phase diagrams of materials are thought of as static, without temporal evolution. However, many functional properties of materials arise as a result of complex temporal changes in the material occurring on different timescales. Hitherto, such properties were not considered within the context of a temporally-evolving phase diagram, even though, under non-equilibrium conditions, different phases typically evolve on different timescales. Here, by using time-resolved optical techniques and femtosecond-pulse-excited scanning tunneling microscopy (STM), we track the evolution of the metastable states in a material that has been of wide recent interest, the quasi-two-dimensional dichalcogenide 1T-TaS2. We map out its temporal phase diagram using the photon density and temperature as control parameters on timescales ranging from 10−12 to 103 s. The introduction of a time-domain axis in the phase diagram enables us to follow the evolution of metastable emergent states created by different phase transition mechanisms on different timescales, thus enabling comparison with theoretical predictions of the phase diagram, and opening the way to understanding of the complex ordering processes in metastable materials.

Emergence of a Promiscuous Peroxidase Under Non‐Equilibrium Conditions

2021 ◽  
Author(s):  
Sumit Pal ◽  
Antara Reja ◽  
Subhajit Bal ◽  
Baishakhi Tikader ◽  
Dibyendu Das
Keyword(s):  
Equilibrium Conditions ◽  
Non Equilibrium

Percentage depth dose fragmentation for investigating and assessing the photon beam dosimetry quality

2018 ◽  
Vol 18 (03) ◽  
pp. 280-284 ◽  
Author(s):  
Mohamed Bencheikh ◽  
Abdelmajid Maghnouj ◽  
Jaouad Tajmouati
Keyword(s):  
Exponential Decay ◽  
Target Volume ◽  
Photon Beam ◽  
Field Size ◽  
Photon Beams ◽  
Energy Agency ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Beam Dosimetry

AbstractAimThe purpose of this study is to introduce a new approach to assess the dosimetry quality of photon beam with energy and irradiation field size. This approach is based on percentage depth dose (PDD) fragmentation for investigating the dosimetry quality.Materials and methodsFor the investigation of the dosimetry quality of 6 and 18 MV photon beams, we have proceeded to fragment the PDD at different field sizes. This approach checks the overall PDD and is not restricted to the exponential decay regions, as per the International Atomic Energy Agency Technical Reports Series No 398 and the American Association of Physicist in Medicine Task Group 51 recommendations.Results and discussionThe 6 MV photon beam deposited more energy in the target volume than the 18 MV photon beam. The dose delivered by the 6 MV beam is greater by a factor of 1·5 than that delivered by the 18 MV beam in the build-up region and the dose delivered by the 6 MV beam is greater by a factor of 2·6 than that delivered by the 18 MV beam in the electronic equilibrium and the exponential decay regions.ConclusionThe dose measured at different points of the beam is higher for 6 MV than for 18 MV photon beam. Therefore, the 6 MV beam is more dosimetrically efficient than the 18 MV beam. Using the proposed approach, we can assess the dosimetry quality by taking into account overall PDD not only in the exponential decay region but also in the field.

scholarly journals Quantification of fast molecular adhesion by fluorescence footprinting

2021 ◽  
Author(s):  
Adam B. Yasunaga ◽  
Isaac T.S. Li
Keyword(s):  
Shear Stress ◽  
Dynamic Range ◽  
Force Distribution ◽  
Equilibrium Conditions ◽  
Ligand Dissociation ◽  
Molecular Adhesion ◽  
Molecular Force ◽  
Adhesion Complex ◽  
Non Equilibrium

AbstractRolling adhesion is a unique process in which the adhesion events are short-lived and operate under highly non-equilibrium conditions. These characteristics pose a challenge in molecular force quantification, where in situ measurement of such forces cannot be achieved with most molecular force sensors that probe near equilibrium. In this report, we demonstrated a quantitative adhesion footprint assay combining DNA-based non-equilibrium force probes and modelling to measure the molecular force involved in fast rolling adhesion. We were able to directly profile the ensemble molecular force distribution during rolling adhesion with a dynamic range between 0 – 18 pN. Our results showed that the shear stress driving bead rolling motility directly controls the molecular tension on the probe-conjugated adhesion complex. Furthermore, the shear stress can steer the dissociation bias of components within the molecular force probe complex, favouring either DNA probe dissociation or receptor-ligand dissociation.

scholarly journals Formation of Hydrides in the Surface Layer of Aluminum in NonEquilibrium Conditions of Electrolyte Plasma

2019 ◽  
Vol 20 (2) ◽  
pp. 181-184
Author(s):  
L. Fedorenkova
Keyword(s):  
Diffusion Layer ◽  
Hydrogen Atoms ◽  
Equilibrium Conditions ◽  
Heating And Cooling ◽  
Polymorphic Modifications ◽  
High Heating ◽  
Aluminum Hydrides ◽  
Micromechanical Characteristics ◽  
Nonequilibrium Conditions ◽  
Non Equilibrium

In this paper, the formation of a diffusion layer on aluminum, which includes aluminum hydrides, in non-equilibrium conditions of electrolyte plasma with high local temperatures, high heating and cooling rates were studied. As a result of the research it was obtained that in the diffusion layer formed complex nanosized inclusions of polymorphic modifications (AlН3)n and AlB3H12. The diffusion in the non-equilibrium conditions of the electrolyte plasma is carried out in hydrogen environment, where the hydrogen atoms have the greatest energy and is one of the main forces that activate the diffusion process and influence the structure, composition and micromechanical characteristics of the diffusion layer.

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