Absorption edge imaging of bacterial endospores

1987 ◽  
Vol 45 ◽  
pp. 882-883
Author(s):  
B. J. Panessa-Warren ◽  
G. T. Tortora ◽  
J. B. Warren
Keyword(s):  
Absorption Edge ◽  
Spore Morphology ◽  
X Rays ◽  
Nitrogen Absorption ◽  
X Ray ◽  
Bacterial Endospores ◽  
Site Of Action ◽  
New Type ◽  
Chemical Sterilization ◽  
Optimal Imaging

Due to the structure and physiology of the bacterial endospore, the resist ratio for most chemical sterilants of spores to vegetative cells is 10,000:1 thereby making them uniquely resistant to chemical sterilization. Although some chemical sterilants do exist that are quite effective against most species of spores, little is known about the effect these chemicals have on spore morphology. This investigation involves the application of a relatively new vanadium-containing sporocide to viable Bacillus subtilis and B. Thuringiensis spores and subsequent microscopy and viability studies to analyze the changes produced after 30 sec, 5 min, 10 min 50 min and 80 min exposure. To try and identify the role, and site of action, of vanadium during spore destruction we attempted a new type of x-ray microscopy utilizing monochromatic x-rays above and below the absorption edge of vanadium (V LII edge). Control x-ray replicas were made at the nitrogen absorption edge (3.09nm) for orientation purposes due to the optimal imaging of protein within the spore. Scanning electron microscopy of sporocide-treated and untreated endospores were used for comparison.

X-Ray absorption edge elemental imaging of B. thuringienis

1989 ◽  
Vol 47 ◽  
pp. 212-213
Author(s):  
R. L. Stears
Keyword(s):  
Absorption Edge ◽  
Elemental Distribution ◽  
X Rays ◽  
Differential Absorption ◽  
Synchrotron Source ◽  
High Brightness ◽  
X Ray ◽  
Elemental Imaging ◽  
Cellular Integrity ◽  
X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

scholarly journals Destruction of tumor mass by gadolinium-loaded nanoparticles irradiated with monochromatic X-rays: Implications for the Auger therapy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kotaro Matsumoto ◽  
Hiroyuki Saitoh ◽  
Tan Le Hoang Doan ◽  
Ayumi Shiro ◽  
Keigo Nakai ◽  
...  
Keyword(s):  
Mesoporous Silica Nanoparticles ◽  
X Rays ◽  
Tumor Spheroids ◽  
Tumor Mass ◽  
X Ray ◽  
Complete Destruction ◽  
New Type ◽  
Efficient Uptake ◽  
A Site ◽  
Shell Energy

Abstract Synchrotron generated monochromatic X-rays can be precisely tuned to the K-shell energy of high Z materials resulting in the release of the Auger electrons. In this work, we have employed this mechanism to destruct tumor spheroids. We first loaded gadolinium onto the surface of mesoporous silica nanoparticles (MSNs) producing gadolinium-loaded MSN (Gd-MSN). When Gd-MSN was added to the tumor spheroids, we observed efficient uptake and uniform distribution of Gd-MSN. Gd-MSN also can be taken up into cancer cells and localize to a site just outside of the cell nucleus. Exposure of the Gd-MSN containing tumor spheroids to monochromatic X-ray beams resulted in almost complete destruction. Importantly, this effect was observed at an energy level of 50.25 keV, but not with 50.0 keV. These results suggest that it is possible to use precisely tuned monochromatic X-rays to destruct tumor mass loaded with high Z materials, while sparing other cells. Our experiments point to the importance of nanoparticles to facilitate loading of gadolinium to tumor spheroids and to localize at a site close to the nucleus. Because the nanoparticles can target to tumor, our study opens up the possibility of developing a new type of radiation therapy for cancer.

The Use op Field Emission Tubes in X-Ray Analysis

1971 ◽  
Vol 15 ◽  
pp. 285-294 ◽  
Author(s):  
J. H. McCrary ◽  
Ted Van Vorous
Keyword(s):  
Steady State ◽  
Field Emission ◽  
High Voltage ◽  
Absorption Edge ◽  
Power Supply ◽  
Quantitative Measure ◽  
X Rays ◽  
Absorption Analysis ◽  
X Ray ◽  
X Ray Absorption

Recently developed, miniature, steady state, field emission tubes are finding application in several areas of x-ray analysis. These tubes require only a high voltage, low current power supply to produce relatively intense beams of x-rays. Since anodes can be fabricated from almost any element, and since the tubes can be operated at potentials up to about 70 kV, many different output x-ray spectra are available. Miniaturized battery operated x-ray sources of this type, occupying a volume of about one liter, have several advantages over radioisotope sources. These include cost, safety, and controllable output spectra and intensity. X-ray sources for energy dispersive fluorescence analyzers are designed so that no scattered characteristic radiations will interfer with the analysis of the sample fluorescence. Sources which are essentially monoenergetic can be fabricated for use in non-dispersive x-ray fluorescence analyzers. Because of the intensity and safety of the field emission tubes, such analyzers can be made which are sensitive while compact, portable, and inexpensive. In x-ray absorption analysis the measurement of absorption edge jump ratios provides a quantitative measure of sample impurities. Field emission tubes whose output spectra consist primarily of bremsstrahlung are particularly well suited to such measurements. The techniques involved in using these tubes in x-ray analysis are described.

Escape Peaks in X-Ray Diffractometry*

1964 ◽  
Vol 8 ◽  
pp. 118-133 ◽  
Author(s):  
William Parrish
Keyword(s):  
Absorption Edge ◽  
Pulse Height ◽  
Pulse Amplitude ◽  
Silicon Powder ◽  
X Rays ◽  
Pulse Height Analyzer ◽  
Escape Peak ◽  
X Ray ◽  
Absorption Edge Energy ◽  
Detector Element

AbstractEscape peaks occur when the incident X-ray quantum, energy exceeds the absorption edge energy of the detector element and the resulting X-ray fluorescence is lost from the detector. The most common escape peaks result from 1 K-fluorescence in NaI-scintillation counters and Xe K-, Xe L-, and Kr K-fluorescence in proportional counters. The average pulse amplitude of the escape peak is proportional to the difference of the Energies of the incident and fluorescent X-rays. If the intensity of the escape peak is high as in the case of Mo Kα and a kryptoopreportional counter, and the lower level of the pulse height analyzer is raised to reject the escape peak, the quantum counting efficiency may be reduced by a factor of two. When the pulse height analyzer is set for characteristic incident radiation, escape peaks appear in powder patterns at small diffraction angles. These broad low-intensity peaks are often mistakenly identified as resulting from misalignment, scattering, etc. Each powder reflection can produce its own escape peak which occurs at an angle slightly smaller than the absorption edge of the detector element. In a silicon powder pattern the three strongest reflections produce three resolved escape peaks whose peak intensities are about 4% of their corresponding Cu Kα peaks when the X-ray tube is operated at 50 kV. The escape peak intensities decrease with decreasing X-ray tube voltage and disappear when the voltage is lower than the absorption edge energy of the detector element. Absorption edge peaks observed without the upper level of the pulse height analyzer are similar in appearance, intensity, and diffraction angle to the escape peaks. In complex powder patterns the escape peak pattern is unresolved and may produce a number of very broad peaks.

scholarly journals Face-on SS 433 Stars as a Possible New Type of Extragalactic X-Ray Sources

2001 ◽  
Vol 205 ◽  
pp. 268-269 ◽  
Author(s):  
S. Fabrika ◽  
A. Mescheryakov
Keyword(s):  
X Rays ◽  
Relativistic Jets ◽  
Expected Frequency ◽  
X Ray ◽  
Ss 433 ◽  
Sky Survey ◽  
Supercritical Accretion ◽  
The Face ◽  
New Type ◽  
Positive Correlations

The object SS433 is a well-known source of relativistic jets, which are formed in supercritical accretion disk. It is very probable that the disk has polar channels and their radiation is collimated (the photo-cones). A face-on SS433 object can appear as ultra-bright and highly variable X-ray source, Lx ˜ 1040 − 1042 erg/s. We discuss the properties of these hypothetical objects and their frequency expected in galaxies. We describe a search for such objects using the ROSAT All Sky Survey and RC3 catalog of galaxies. Among the total 418 positive correlations we find that 142 sources in S and Irr galaxies are unknown as AGNs. Nuclear sources among them still contain many AGNs. Non-nuclear (offset) sources are rather hard, their X-ray luminosities are 1039 − 1041 erg/s. Their observed frequency is about 4–5% per galaxy, that is in agreement with expected frequency of the face-on SS 433 stars. The only way to recognize such stars is their expected violent variability in X rays.

scholarly journals IVAN PULUJ AND THE DISCOVERY OF X-RAYS

2021 ◽  
Vol 64 (1) ◽  
Author(s):  
Ulyana Pidvalna ◽  
◽  
Roman Plyatsko ◽  
Vassyl Lonchyna ◽  
◽  
...  
Keyword(s):  
International Exhibition ◽  
Bone Lesions ◽  
X Rays ◽  
High Quality ◽  
X Ray ◽  
Exact Date ◽  
Starting Point ◽  
The World ◽  
New Type ◽  
The Given

On January 5, 1896, the Austrian newspaper Die Presse published an article entitled “A Sensational Discovery”. It was dedicated to the discovery of X-rays made on November 8, 1895 by the German physicist Wilhelm Conrad Röntgen. Having taken into account the contribution of other scientists, the precondition of the given epochal, yet unexpected, discovery was, first and foremost, the work of the Ukrainian scientist Ivan Puluj. It was Puluj who laid the foundation for X-ray science. He explained the nature of X-rays, discovered that they can ionize atoms and molecules, and defined the place of X-ray emergence and their distribution in space. In 1881, Puluj constructed a cathode lamp (“Puluj’s tube”) which was fundamentally a new type of light source. In the same year, in recognition of this discovery, Puluj received an award at the International Exhibition in Paris. Investigating the processes in cathode-ray tubes, Ivan Puluj set the stage for two ground-breaking discoveries in physics, namely X-rays and electrons. Puluj used his cathode lamp in medicine as a source of intense X-rays which proved to be highly efficient. The exact date of the first X-ray images received by Puluj remains unknown. High-quality photographs of the hand of an eleven-year-old girl, taken on January 18, 1896, are preserved. Multiple X-ray images clearly visualized pathological changes in the examined structures (fractures, calluses, tuberculous bone lesions). High-quality images were obtained by means of the anticathode in the design of Puluj’s lamp, which was the first in the world. The image of the whole skeleton of a stillborn child (published on April 3, 1896 in The Photogram) is considered to be the starting point of using X-rays in anatomy.

Silicon Detector System for X-Ray Pulse Calorimetry of Laser-Produced Plasmas*

1974 ◽  
Vol 18 ◽  
pp. 213-221 ◽  
Author(s):  
J. H. McQuaid ◽  
C. E. Violet ◽  
J. Petruzzi
Keyword(s):  
Silicon Detector ◽  
Direct Conversion ◽  
X Rays ◽  
Electron Pairs ◽  
Analog To Digital ◽  
X Ray ◽  
New Type ◽  
A Charge ◽  
Readout Scheme ◽  
Charge Sensitive Preamplifier

AbstractThe instrumentation for measuring x-ray yields from laser produced plasma is described. This new type of calorimeter is composed of a silicon detector, a charge-sensitive preamplifier and an analog-to-digital readout scheme for multiplexing up to ten detector outputs.X-rays interacting with the detector produce hole-electron pairs in proportion to the total energy lost in the detector (∼1012 eV). In this application the detector can be characterized as a solid-state ionization chamber. The detector signal is coupled to a charge-sensitive preamplifier which generates a voltage pulse proportional to the x-ray energy absorbed. In this way the x-ray energy is measured by “direct conversion” rather than measuring the temperature rise due to an energy flux.

Heavy Ion-Induced Characteristic X-Ray Generation as an Analytical Probe

1970 ◽  
Vol 14 ◽  
pp. 173-183 ◽  
Author(s):  
J. A. Cairns ◽  
D. F. Holloway ◽  
R. S. Nelson
Keyword(s):  
Cross Sections ◽  
Heavy Ions ◽  
Proton Irradiation ◽  
Heavy Ion ◽  
X Rays ◽  
X Ray ◽  
The Past ◽  
Tracer Techniques ◽  
New Type ◽  
Gas Volume

AbstractIncreasing attention is currently focused on the generation of characteristic x-ray by proton irradiation. This has the advantage of yielding “clean” x-ray- i. e. free from background brerasstrahlung radiation, from even the lightest elements. The disadvantage is that the yields are naturally much lower than those produced by electrons of the same energy. A recent study has extended characteristic x-ray production to a variety of heavy ions and has shown that the cross- sections for the production of clean x-rays are often higher , by as much as several orders of magnitude, than those produced by protons of the same energy. In addition, there has emerged a further advantage, viz. the ability of specially chosen heavy ions to excite characteristic x-ray from a particular element in a selective manner. Since heavy ions penetrate only a few hundred Angstroms in to most solids, the phenomenon can be used as the basis of a technique for the examination of surface deposits, or to measure depth distributions of impurities. For example, Kr ions can be used t o determine the range distribution of antimony which had been implanted in to silicon at 100 keV. The antimony concentration was determined as a function of ∼ 150 Å steps, and was found to exhibit a maximum concentration of ∼ 1 part in 103 of silicon at 450 Å below the surface, falling to zero concentration at ∼2000 Å a depth. In the past, in order to obtain the required degree of sensitivity, such range determinations have relied on radio active tracer techniques.An entirely new type of proportional counter has been developed during the course of these studies. This instrument, because of its special construction, can be positioned very close to targets in non-dispersive studies, so as to collect the highest possible fraction of emitted x-ray. It incorporates a replaceable anode unit, together with a built- in miniature head amplifier, and exhibits extremely good performance, particularly for ultra-soft x-ray. In addition, rotation of a dial on the end of the counter body allows alteration of the active gas volume during operation, and so permits tuning into x-rays of a particular energy.

IN-VIVO ELEMENTAL ANALYSIS BY PIXE-μ-CT

2007 ◽  
Vol 17 (01n02) ◽  
pp. 41-46 ◽  
Author(s):  
Y. KAWAMURA ◽  
K. ISHII ◽  
H. YAMAZAKI ◽  
S. MATSUYAMA ◽  
Y. KIKUCHI ◽  
...  
Keyword(s):  
High Resolution ◽  
Absorption Edge ◽  
Ion Beam ◽  
Projection Data ◽  
Elemental Distribution ◽  
X Rays ◽  
Ct Reconstruction ◽  
3D Images ◽  
X Ray

We have developed “micron-CT”, using micro-PIXE for in-vivo imaging. This system comprises an X-ray CCD camera (Hamamatsu photonics C8800X9) with high resolution (pixel size: 8×8 μm 2, number of pixels: 1000×1000) and an X-ray-point-source with a spot size of 1.5×1.5 μm 2 which is generated by irradiation of a microbeam on a pure metal target. Thus we can acquire projection data with high resolution. The sample is placed in a small diameter tube and is rotated by a stepping motor. The 3D images were reconstructed from the obtained projection data by using cone-beam CT reconstruction algorithm. X-ray spectra produced by heavy charged particle bombardment, exhibit a much smaller continuous background compared to electron bombardment. Therefore, X-rays produced by ion beam can be used as a monochromatic and low energy X-ray source. The feature is very effective to investigate small insects. Moreover we can get elemental distribution image of object by choosing appropriate characteristic X-rays corresponding to the absorption edge. On the other hand, the conventional X-ray CT, in which continuous X-rays are used, provides images of the electron density in the object. Using this system, we were able to get 3D images of a living ant's head with 6 μm spatial resolution. By using Fe - K -X-rays (6.40 keV) and Co - K -X-rays (6.93 keV), we can investigate the 3D distribution of Mn ( K -absorption edge = 6.54 keV) in an ant's head.

scholarly journals X-ray induced photodynamic therapy with copper-cysteamine nanoparticles in mice tumors

2019 ◽  
Vol 116 (34) ◽  
pp. 16823-16828 ◽  
Author(s):  
Samana Shrestha ◽  
Jing Wu ◽  
Bindeshwar Sah ◽  
Adam Vanasse ◽  
Leon N Cooper ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Treatment Method ◽  
The Body ◽  
Target Cells ◽  
X Rays ◽  
X Ray ◽  
Mouse Tumors ◽  
Study Results ◽  
New Type

Photodynamic therapy (PDT), a treatment that uses a photosensitizer, molecular oxygen, and light to kill target cells, is a promising cancer treatment method. However, a limitation of PDT is its dependence on light that is not highly penetrating, precluding the treatment of tumors located deep in the body. Copper-cysteamine nanoparticles are a new type of photosensitizer that can generate cytotoxic singlet oxygen molecules upon activation by X-rays. In this paper, we report on the use of copper-cysteamine nanoparticles, designed to be targeted to tumors, for X-ray–induced PDT. In an in vivo study, results show a statistically significant reduction in tumor size under X-ray activation of pH-low insertion peptide–conjugated, copper-cysteamine nanoparticles in mouse tumors. This work confirms the effectiveness of copper-cysteamine nanoparticles as a photosensitizer when activated by radiation and suggests that these Cu-Cy nanoparticles may be good candidates for PDT in deeply seated tumors when combined with X-rays and conjugated to a tumor-targeting molecule.

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