scholarly journals High Energy Radiation-Induced Aggregation of Plasma Proteins. Time Resolved Light Scattering Measurements

1980 ◽  
Vol 35 (2) ◽  
pp. 217-220 ◽  
Author(s):  
H. Kihara ◽  
W. Schnabel
Keyword(s):  
High Energy ◽  
Relative Increase ◽  
Protein Solutions ◽  
Oh Radicals ◽  
Time Resolved ◽  
Short Pulses ◽  
Radiation Chemical ◽  
Protein Molecules ◽  
Radiation Induced ◽  
Induced Aggregation

Abstract Human immunoglobulin (IgG), bovine fibrinogen and bovine serum albumin were irradiated at room temperature with short pulses (50 ns to 2 μs) of 16 MeV electrons in 0.2 M NaClO4 solution containing phosphate buffer (pH 7.5). In the presence of N2O the intensity of light (LSI) scattered by the protein solutions increased after the pulse indicating aggregation. The latter process originates from the attack of protein molecules by OH radicals (aggregation is impeded by t-butanol and augmented by N2O). Upon plotting the relative increase of LSI vs. log time (after the pulse) sigmoidally shaped curves were obtained.From these findings and results of optical absorption measurements the following is inferred: Aggregation occurs as a consequence of chemical alterations of the protein molecules induced by the attack by OH radicals. The transient species formed during and a few pis after the pulse are reacting within a period of several ms. At the end of this period the formation of aggregates starts. It is concluded that the primary radiation chemical process consists (among others) in the generation of nuclcation sites. The latter subsequently initiate aggregation processes.

Radiation Chemical Studies of the Oxidation of Aniline in Aqueous Solution

1985 ◽  
Vol 40 (10) ◽  
pp. 1026-1039 ◽  
Author(s):  
Ling Qin ◽  
G. N. R. Tripathi ◽  
Robert H. Schüler
Keyword(s):  
Aqueous Solution ◽  
Electron Transfer ◽  
Radical Cation ◽  
Time Scale ◽  
Radical Cations ◽  
Oh Radicals ◽  
Basic Solution ◽  
Direct Oxidation ◽  
Time Resolved ◽  
Radiation Chemical

Oxidation of aniline in aqueous solution by ·OH radicals proceeds predominantly via addition to the ring followed by elimination of OH- on the microsecond time scale to form the aniline radical cation. Direct oxidation by electron transfer accounts for less than 4% of the ·OH reactions. The different hydroxycyclohexadienyl isomers produced by ·OH addition decay at different rates with this decay catalyzed both by protons and phosphate. In basic solution the resultant radical cation deprotonates to form the anilino radical. The p Ka for the equilibrium between the acidic and basic forms of this radical is 7.05 ± 0.05. Secondary radicals such as Br2·- or N3· oxidize aniline directly by electron transfer and allow rapid preparation of the radical cation even in basic solution, as is conclusively demonstrated by observation of the Raman spectrum of the radical cation on the nanosecond time scale at pH 10.4. The deprotonation process can be followed directly by time resolved absorption spectrophotometry in the pH range of 9 - 11 and is shown to occur via reaction of the radical cation with OH- at a rate constant of 2.2 x 1010 M-1 s-1. Reaction of anilino radical with water is relatively slow (k ~ 2 x 103 s-1). Time resolved Raman methods show that benzidine radical cation is an important tertiary transient, indicating that second order reaction between radical cations results to an appreciable extent from coupling at ring positions.

High Energy Radiation-Induced Crosslinking of Histone Octamer Complexes

1984 ◽  
Vol 39 (11-12) ◽  
pp. 1075-1078 ◽  
Author(s):  
K.-J. Deeg ◽  
L. Katsikas ◽  
W. Schnabel
Keyword(s):  
Aqueous Solution ◽  
High Energy ◽  
Oh Radicals ◽  
Native State ◽  
High Energy Radiation ◽  
Histone Octamer ◽  
Calf Thymus ◽  
Dilute Aqueous Solution ◽  
Radiation Induced ◽  
Γ Rays

Abstract Calf thymus histone octamer complexes were irradiated in the native state in N2O-saturated dilute aqueous solution (0.5 g/l, pH 9, [NaClO4] = 1-4 mol/1) with 50 or 100 ns pulses of 16 MeV electrons or 60Co-γ-rays. Tim e resolved light scattering measurem ents and optical ab­sorption measurements yielded the following: the octamers underwent a volume contraction due to intra-complex-crosslinking induced by the attack of OH-radicals. Crosslinking proceeded to a certain extent via 2 ,2′-biphenol coupling as inferred from product analyses.

In situ TEM studies of irradiation effects for materials improvement

1991 ◽  
Vol 49 ◽  
pp. 452-453
Author(s):  
Charles W. Allen
Keyword(s):  
Nuclear Reactor ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Point Of View ◽  
In Situ Tem ◽  
Irradiation Effects ◽  
Tem Analysis ◽  
Radiation Induced ◽  
Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

The promises and perfidy of cryomicroscopy and analysis

1994 ◽  
Vol 52 ◽  
pp. 382-383
Author(s):  
Patrick Echlin
Keyword(s):  
Low Temperature ◽  
High Energy ◽  
Short Paper ◽  
List Type ◽  
Time Resolved ◽  
Energy Beam ◽  
Cellular Analysis ◽  
Dissolved Ions ◽  
Embedding Medium ◽  
Low Temperature Microscopy

The unusual title of this short paper and its accompanying tutorial is deliberate, because the intent is to investigate the effectiveness of low temperature microscopy and analysis as one of the more significant elements of the less interventionist procedures we can use to prepare, examine and analyse hydrated and organic materials in high energy beam instruments. The promises offered by all these procedures are well rehearsed and the litany of petitions and responses may be enunciated in the following mantra.Vitrified water can form the perfect embedding medium for bio-organic samples.Frozen samples provide an important, but not exclusive, milieu for the in situ sub-cellular analysis of the dissolved ions and electrolytes whose activities are central to living processes.The rapid conversion of liquids to solids provides a means of arresting dynamic processes and permits resolution of the time resolved interactions between water and suspended and dissolved materials.The low temperature environment necessary for cryomicroscopy and analysis, diminish, but alas do not prevent, the deleterious side effects of ionizing radiation.Sample contamination is virtually eliminated.

A review on radiation induced nausea and vomiting: “Current management strategies and prominence of radio sensitizers”

2021 ◽  
pp. 107815522110115
Author(s):  
Meenu Vijayan ◽  
Sherin Joseph ◽  
Emmanuel James ◽  
Debnarayan Dutta
Keyword(s):  
Radiation Therapy ◽  
Cell Damage ◽  
Genetic Material ◽  
High Energy ◽  
Concurrent Chemotherapy ◽  
Nausea And Vomiting ◽  
Dose Fractionation ◽  
Psychological State ◽  
Related Factors ◽  
Radiation Induced

Radiations dissipated are high energy waves used mostly as treatment intervention in controlling the unwanted multiplication of cell. About 60%–65% of cancer treatment requires radiation therapy and 40%–80% of radiation therapy causes RINV which are true troublemakers. Radiation therapy (RT) is targeted therapy mostly used to treat early stages of tumour and prevent their reoccurrence. They mainly destroy the genetic material (DNA) of cancerous cells to avoid their unwanted growth and division. The RINV affects the management and quality of life of patients which further reduces the patient outcome. RINV depends on RT related factors (dose, fractionation, irradiation volume, RT techniques) and patient related factors like (gender, health conditions, age, concurrent chemotherapy, psychological state, and tumour stage). RT is an active area of research and there is only limited progress in tackling the RINV crisis. Advanced technological methods are adopted that led to better understanding of total lethal doses. Radiation therapy also affects the immunity system that leads to radiation induced immune responses and inflammation. Radio sensitizers are used to sensitize the tumour cells to radiations that further prevent the normal cell damage from radiation exposure. There is a need for future studies and researches to re-evaluate the data available from previous trials in RINV to make better effective antiemetic regimen. The article focuses on radiation therapy induced nausea and vomiting along with their mechanism of action and treatment strategies in order to have a remarkable patient care.

Dosimetry of High-Energy Photon Beams Based on Standards of Absorbed Dose to Water: Abstract

2001 ◽  
Vol 1 (1) ◽  
pp. 8-8 ◽  
Author(s):  
K. Hohlfeld ◽  
P. Andreo ◽  
O. Mattsson ◽  
J. P. Simoen
Keyword(s):  
Reference Conditions ◽  
International Comparisons ◽  
Absorbed Dose ◽  
High Energy ◽  
National Standards ◽  
Photon Radiation ◽  
Photon Beams ◽  
Radiation Induced ◽  
Absorbed Dose To Water ◽  
Primary Standards

This report examines the methods by which absorbed dose to water can be determined for photon radiations with maximum energies from approximately 1 MeV to 50 MeV, the beam qualities most commonly used for radiation therapy. The report is primarily concerned with methods of measurement for photon radiation, but many aspects are also relevant to the dosimetry of other therapeutic beams (high-energy electrons, protons, etc.). It deals with methods that are sufficiently precise and well established to be incorporated into the dosimetric measurement chain as primary standards (i.e., methods based on ionisation, radiation-induced chemical changes, and calorimetry using either graphite or water). The report discusses the primary dose standards used in several national standards laboratories and reviews the international comparisons that have been made. The report also describes the reference conditions that are suitable for establishing primary standards and provides a formalism for determining absorbed dose, including a discussion of correction factors needed under conditions other than those used to calibrate an instrument at the standards laboratory.

Detector commissioning and development for PETRA-III

2010 ◽  
Vol 1 (SRMS-7) ◽  
Author(s):  
David Pennicard ◽  
Heinz Graafsma ◽  
Michael Lohmann
Keyword(s):  
High Speed ◽  
Materials Science ◽  
Dynamic Range ◽  
Photon Counting ◽  
High Energy ◽  
X Rays ◽  
Silicon Detectors ◽  
Time Resolved ◽  
Wide Range ◽  
Synchrotron Light

The new synchrotron light source PETRA-III produced its first beam last year. The extremely high brilliance of PETRA-III and the large energy range of many of its beamlines make it useful for a wide range of experiments, particularly in materials science. The detectors at PETRA-III will need to meet several requirements, such as operation across a wide dynamic range, high-speed readout and good quantum efficiency even at high photon energies. PETRA-III beamlines with lower photon energies will typically be equipped with photon-counting silicon detectors for two-dimensional detection and silicon drift detectors for spectroscopy and higher-energy beamlines will use scintillators coupled to cameras or photomultiplier tubes. Longer-term developments include ‘high-Z’ semiconductors for detecting high-energy X-rays, photon-counting readout chips with smaller pixels and higher frame rates and pixellated avalanche photodiodes for time-resolved experiments.

scholarly journals Improved Phebus laser performances required for precision laser–target experiments

1998 ◽  
Vol 16 (2) ◽  
pp. 253-265 ◽  
Author(s):  
G. Thiell ◽  
R. Bailly-Salins ◽  
J.L. Bruneau ◽  
G. Coulaud ◽  
P. Estraillier ◽  
...  
Keyword(s):  
Laser Energy ◽  
Incident Beam ◽  
High Energy ◽  
Target Chamber ◽  
Laser Target ◽  
Time Resolved ◽  
X Ray ◽  
Target Experiment ◽  
Pointing Precision ◽  
Energy Shots

The Precision Phebus program, started in 1993, emphasizes a series of laser and target experiment objectives on the two-beam Phebus Nd-phosphate glass laser. Recently, three major objectives that are also very important issues for megajoule-class lasers have been met: First, the balance of the incident beam-to-beam 3ω power is shown to be in the range from 5 to 12% for 3-ns, 3ω-shaped pulses of reproducible high-energy shots; second, the smoothing uniformity of the laser energy deposited on the target, that is, the contrast of the spatial beam modulations, can be kept lower than 5%; and, finally, the tight control of the beam targeting leads to a pointing precision of less than 10 μrd on the target at the target chamber center (TCC) and of 80 μrd on X-ray sources located up to 3 cm from the TCC to improve the space- and time-resolved X-ray shadowgraphy techniques performed for target physics experiments such as implosion and hydrodynamical instability studies.

scholarly journals Overheating In Silicon During Pulsed-Laser Irradiation?

1985 ◽  
Vol 51 ◽  
Author(s):  
B. C. Larson ◽  
J. Z. Tischler ◽  
D. M. Mills
Keyword(s):  
Laser Irradiation ◽  
Thermal Strain ◽  
Pulsed Laser ◽  
Interface Velocity ◽  
High Energy ◽  
Time Resolved ◽  
Synchrotron Source ◽  
Zero Velocity ◽  
The Difference ◽  
Pulsed Laser Irradiation

ABSTRACTNanosecond resolution time-resolved x-ray diffraction measurements of thermal strain have been used to measure the interface temperatures in silicon during pulsed-laser irradiation. The pulsed-time-structure of the Cornell High Energy Synchrotron Source (CHESS) was used to measure the temperature of the liquid-solid interface of <111> silicon during melting with an interface velocity of 11 m/s, at a time of near zero velocity, and at a regrowth velocity of 6 m/s. The results of these measurements indicate 110 K difference between the temperature of the interface during melting and regrowth, and the measurement at zero velocity shows that most of the difference is associated with undercooling during the regrowth phase.

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