scholarly journals The Bacteriostatic and Bactericidal Effects of Radiation from Dental and Medical X-Rays

2020 ◽  
Vol 45 (1) ◽  
pp. 3-14
Author(s):  
Winston I. Lu ◽  
Dominic P. Lu
Keyword(s):  
Cancer Therapy ◽  
Ring Test ◽  
High Dose ◽  
Time Interval ◽  
X Rays ◽  
Oral Flora ◽  
Bacterial Colony ◽  
X Ray ◽  
Research Experiment ◽  
Micro Organisms

The purpose of this research was to proce or disprove the widely held beliefs that X-ray radiation used in medical or dental applications may affect the normal oral flora, and may also have effects on the micro-organisms existing in the oral cavity of every person. Such beliefs might be due to the common knowledge that radiation therapy has been utilized for the long time in the cancer patients to destroy the cancerous cells, and that radiation are also widely used in agriculture to prolong the shelf life of the farm products by destroying the decay-causing microorganisms existing in the agricultural products such as meats, produce, etc. Since very few research has been conducted in this concerned area, and not much pertinent information in the scientific literature could be found in this regard, a research experiment was set up to find out if these common beliefs have any merits. The research experiment involved selecting BDORT(By-digital O-Ring Test) positive dishes to incubate human saliva collected from a volunteer patient. Once dish served as control which was not subjected X-ray irradiation. Other dishes were subjected X-ray irradiation with various doses of irradiation strength at various time interval such as 1, 3, 5, 7, and 9 seconds to find out if any significant change taken place in the bacteria colonies. The bacterial colonies in the irradiated dishes then compared with that of the control dish so as to draw a conclusion if radiation for medical and dental X-ray machines would actually have any bactericidal or/and bacteriostatic effects on the oral micro-organisms flora. Finally, dishes were brought to a local hospital Radiology Department to use high dose of irradaition (used for cancer therapy) on the dishes to find out to what extent if such a high dose X-ray irradiation emitted from therapeutic cancer therapy machine would affect the number of bacterial colonies in the dishes as when compared with when dishes were under low doses of X-ray irradiation from dental or medical diagnostic X-ray machines. During the experiment, dishes, when irradiated, were sent to a certified medical technologist in the hospital laboratory to count the number of the bacterial colonies, and each change in the bacterial colony number were recorded in to data for biostatic analysis. The data were compared with BDORT negativity scores collected each time before and after dishes were irradiated, thus to find out if any corresponding confirmity between traditional laboratory findings and the score changes from BDORT findings. The results of this experiment revealed the fact that radiation from regular diagnostic X-ray machines possess little effect on bacteria, and that they have little effect on both cells and bacteria present in the human body. Neverthless, dramatically increasing the high radiation dosages does have potential to both inhibit and destroy bacteria. Therefore,using irradiation techniques to inhibit bacterial growth is only useful in agriculture practices, since tens of thousands of irradaiation dosages are necessary for bacteria inhibition. in human, over 500 RADs (radiation absorption dose) is lethal. Therefore, bacterial inhibition could not be practical in humans since it requires tens of thousands of RADs to be useful in the aspect.

In situ time-resolved X-ray diffraction of tobermorite formation process under hydrothermal condition: Influence of reactive al compound

2011 ◽  
Vol 26 (2) ◽  
pp. 134-137 ◽  
Author(s):  
K. Matsui ◽  
A. Ogawa ◽  
J. Kikuma ◽  
M. Tsunashima ◽  
T. Ishikawa ◽  
...  
Keyword(s):  
Hydrothermal Reaction ◽  
High Energy ◽  
Saturated Steam ◽  
Array Detector ◽  
Time Interval ◽  
X Rays ◽  
X Ray Diffraction ◽  
Formation Reaction ◽  
X Ray

Hydrothermal formation reaction of tobermorite in the autoclaved aerated concrete (AAC) process has been investigated by in situ X-ray diffraction. High-energy X-rays from a synchrotron radiation source in combination with a newly developed autoclave cell and a photon-counting pixel array detector were used. XRD measurements were conducted in a temperature range 100–190°C throughout 12 h of reaction time with a time interval of 4.25 min under a saturated steam pressure. To clarify the tobermorite formation mechanism in the AAC process, the effect of Al addition on the tobermorite formation reaction was studied. As intermediate phases, non-crystalline calcium silicate hydrate (C-S-H), hydroxylellestadite (HE), and katoite (KA) were clearly observed. Consequently, it was confirmed that there were two reaction pathways via C-S-H and KA in the tobermorite formation reaction of Al containing system. In addition, detailed information on the structural changes during the hydrothermal reaction was obtained.

scholarly journals Nanomelanin Potentially Protects the Spleen from Radiotherapy-Associated Damage and Enhances Immunoactivity in Tumor-Bearing Mice

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1725 ◽  
Author(s):  
Nguyen Thi Le Na ◽  
Sai Duc Loc ◽  
Nguyen Le Minh Tri ◽  
Nguyen Thi Bich Loan ◽  
Ho Anh Son ◽  
...  
Keyword(s):  
Cancer Treatment ◽  
Interleukin 2 ◽  
High Dose Rate ◽  
High Dose ◽  
X Rays ◽  
Necrosis Factor Alpha ◽  
Oh Groups ◽  
X Ray ◽  
Tumor Bearing ◽  
Tnf Α

Radiotherapy side-effects present serious problems in cancer treatment. Melanin, a natural polymer with low toxicity, is considered as a potential radio-protector; however, its application as an agent against irradiation during cancer treatment has still received little attention. In this study, nanomelanin particles were prepared, characterized and applied in protecting the spleens of tumor-bearing mice irradiated with X-rays. These nanoparticles had sizes varying in the range of 80–200 nm and contained several important functional groups such as carboxyl (-COO), carbonyl (-C=O) and hydroxyl (-OH) groups on the surfaces. Tumor-bearing mice were treated with nanomelanin at a concentration of 40 mg/kg before irradiating with a single dose of 6.0 Gray of X-ray at a high dose rate (1.0 Gray/min). Impressively, X-ray caused mild splenic fibrosis in 40% of nanomelanin-protected mice, whereas severe fibrosis was observed in 100% of mice treated with X-ray alone. Treatment with nanomelanin also partly rescued the volume and weight of mouse spleens from irradiation through promoting the transcription levels of splenic Interleukin-2 (IL-2) and Tumor Necrosis Factor alpha (TNF-α). More interestingly, splenic T cell and dendritic cell populations were 1.91 and 1.64-fold higher in nanomelanin-treated mice than those in mice which received X-ray alone. Consistently, the percentage of lymphocytes was also significantly greater in blood from nanomelanin-treated mice. In addition, nanomelanin might indirectly induce apoptosis in tumor tissues via activation of TNF-α, Bax, and Caspase-3 genes. In summary, our results demonstrate that nanomelanin protects spleens from X-ray irradiation and consequently enhances immunoactivity in tumor-bearing mice; therefore, we present nanomelanin as a potential protector against damage from radiotherapy in cancer treatment.

Kaonic hydrogen X-rays — experiments at DAFNE

2007 ◽  
Vol 85 (5) ◽  
pp. 479-485 ◽  
Author(s):  
M Cargnelli ◽  
T Ishiwatari ◽  
P Kienle ◽  
J Marton ◽  
E Widmann ◽  
...  
Keyword(s):  
Chiral Symmetry Breaking ◽  
Low Energy ◽  
Kaonic Hydrogen ◽  
X Rays ◽  
Large Area ◽  
X Ray ◽  
Kaonic Deuterium ◽  
Research Experiment ◽  
Scattering Lengths ◽  
Excellent Energy Resolution

At the DAΦNE electron–positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons produced in the Φ-meson decay. The low-energy kaon–nucleon interaction in kaonic hydrogen and kaonic deuterium can be investigated under favorable conditions. The DEAR (DAΦNE Exotic Atom Research) experiment at LNF delivered the most precise data on kaonic hydrogen up to now. DEAR and its follow-up experiment SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Application) are using X-ray spectroscopy of kaonic hydrogen and kaonic deuterium atoms to measure the strong interaction-induced shift and width of the ground state. From these quantities the isospin-dependent antikaon–nucleon scattering lengths can be determined, quantities useful for testing the understanding of chiral symmetry breaking in the strangeness sector. Within the SIDDHARTA project new X-ray detectors are being developed. We will use an array of large area silicon drift detectors (SDDs) having excellent energy resolution but also providing a timing capability that will result in a huge suppression of background and so overcome the precision limits of the former experiments.PACS Nos.: 36.10.k, 13.75.Jz, 32.30.Rj and 29.40.Wk

scholarly journals Sponges are highly resistant to radiation exposure and cancer

2021 ◽  
Author(s):  
Angelo Fortunato ◽  
Jake Taylor ◽  
Jonathan Scirone ◽  
Athena Aktipis ◽  
Carlo Maley
Keyword(s):  
Somatic Cell ◽  
Epithelial To Mesenchymal Transition ◽  
Lethal Dose ◽  
High Dose ◽  
X Rays ◽  
Cell Turnover ◽  
Cancer Resistance ◽  
Mesenchymal Transition ◽  
X Ray ◽  
Adaptive Immune Cells

There are no reports of cancer in sponges, despite them having somatic cell turnover, long lifespans and no specialized adaptive immune cells. In order to investigate whether sponges are cancer resistant, we exposed a species of sponge, Tethya wilhelma, to X-rays. We found that T. wilhelma can withstand 600 Gy of X-ray radiation. That is approximately 100 times the lethal dose for humans. A single high dose of X-rays did not induce cancer in sponges, providing the first experimental evidence of cancer resistance in the phylum, Porifera. Following X-ray exposure, we found an overexpression of genes involved in DNA repair, signaling transduction pathways and epithelial to mesenchymal transition. Sponges have the highest level of radiation resistance that has yet been observed in animals that have sustained somatic cell turnover. This may make them an excellent model system for studying cancer resistance and developing new approaches for cancer prevention and treatment.

scholarly journals Measurement of the X-ray proper motion in the south-east rim of RX J1713.7−3946

2017 ◽  
Vol 597 ◽  
pp. A106 ◽  
Author(s):  
Fabio Acero ◽  
Satoru Katsuda ◽  
Jean Ballet ◽  
Robert Petre
Keyword(s):  
Power Law ◽  
Proper Motion ◽  
Ambient Medium ◽  
Time Interval ◽  
X Rays ◽  
The South ◽  
X Ray ◽  
North West ◽  
East Region ◽  
Power Law Index

We report on the first proper motion measurement in the supernova remnant RX J1713.7−3946 using the XMM-Newton X-ray telescope on a 13 yr time interval. This expansion measurement is carried out in the south-east region of the remnant, where two sharp filament structures are observed. For the outermost filament, the proper motion is 0.75+0.05-0.06 ± 0.069syst arcsec yr-1 which is equivalent to a shock speed of ~3500 km s-1 at a distance of 1 kpc. In contrast with the bright north-west region, where the shock is interacting with the border of the cavity, the shock in the south-east region is probably expanding in the original ambient medium carved by the progenitor and can be used to derive the current density at the shock and the age of the remnant. In the case where the shock is evolving in a wind profile (ρ ∝ r− s, s = 2) or in a uniform medium (s = 0), we estimate an age of ~2300 yr and ~1800 yr respectively for an ejecta power-law index of n = 9. The specific case of an ejecta power-law index of n = 7, and s = 0, yields an age of ~1500 yr, which would reconcile RX J1713.7−3946 with the historical records of SN 393. In all scenarios, we derive similar upstream densities of the order of 0.01 cm-3, compatible with the lack of thermal X-rays from the shocked ambient medium.

THE PRODUCTION OF MUTATIONS BY THE IRRADIATION OF MONTCALM BARLEY

1955 ◽  
Vol 33 (6) ◽  
pp. 515-530 ◽  
Author(s):  
Thomas Lawrence
Keyword(s):  
High Dose Rate ◽  
Mutation Induction ◽  
High Dose ◽  
X Rays ◽  
New Approach ◽  
X Ray ◽  
Dose Rates ◽  
Radiation Sources ◽  
Early Maturing ◽  
New Varieties

Five radiation sources were used to induce mutations in barley. All treatments were given at a dosage of 10,000 r. equivalent. The radiation sources with their respective dose-rates in the region of the irradiated seeds were: a betatron (181.8 r./min.), an X-ray machine (201 r./min.), radium-beryllium (5.3 r./min.), and two Co60 sources (4.5 r./min. and 75.75 r./min.). None of the radiation sources used was more effective than the X-ray treatment in producing mutations. The betatron and the high dose-rate treatments from Co60 appear to be somewhat less effective than X-rays. Over 30 different mutant types were produced, including a number of vital mutants, such as stiff-strawed and early-maturing types. These appear promising as new varieties, but require further agronomic evaluation. It is concluded that mutation induction will become a useful new approach for plant breeders.

Rhabdomyosarcoma of the maxillary sinus

1984 ◽  
Vol 98 (4) ◽  
pp. 405-415 ◽  
Author(s):  
M. Suzuki ◽  
Y. Kobayashi ◽  
Y. Harada ◽  
T. Kyo ◽  
H. Dohy ◽  
...  
Keyword(s):  
Maxillary Sinus ◽  
Primary Source ◽  
Metastatic Tumor ◽  
Japanese Woman ◽  
High Dose ◽  
X Rays ◽  
Chemotherapeutic Regimen ◽  
X Ray ◽  
Old Japanese ◽  
Left Maxillary Sinus

AbstractA rare case of adult rhabdomyosarcoma originating from the left maxillary sinus is reported. A 22-year-old Japanese woman was referred to the Department of Otolaryngology, Hiroshima University, for investigation of the primary source of a metastatic tumor in the bone marrow. An X-ray of the sinuses revealed a tumor in the left maxillary sinus with extension into the nasal cavity, ethmoidal and sphenoidal sinuses. The patient was managed with a chemotherapeutic regimen consisting of high-dose methotrexate, adriamycin, vincristine, cyclophosphamide and prednisolone. After three courses of this chemotherapy, the tumor had decreased in size by about 90 per cent, as indicated by X-rays. The remaining tumor was removed by an extended Denker's operation. Following the surgery another seven courses of chemotherapy were given and during the eight months following the operation the patient has been free from any local recurrence.

scholarly journals X-ray Emission Hazards from Ultrashort Pulsed Laser Material Processing in an Industrial Setting

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7163
Author(s):  
Ulf Stolzenberg ◽  
Mayka Schmitt Rahner ◽  
Björn Pullner ◽  
Herbert Legall ◽  
Jörn Bonse ◽  
...  
Keyword(s):  
Material Processing ◽  
High Dose ◽  
Reference Scenario ◽  
X Rays ◽  
Laser Material Processing ◽  
Laser Material ◽  
X Ray ◽  
Dose Rates ◽  
Industrial Setting ◽  
Ambient Dose

Interactions between ultrashort laser pulses with intensities larger than 1013 W/cm2 and solids during material processing can lead to the emission of X-rays with photon energies above 5 keV, causing radiation hazards to operators. A framework for inspecting X-ray emission hazards during laser material processing has yet to be developed. One requirement for conducting radiation protection inspections is using a reference scenario, i.e., laser settings and process parameters that will lead to an almost constant and high level of X-ray emissions. To study the feasibility of setting up a reference scenario in practice, ambient dose rates and photon energies were measured using traceable measurement equipment in an industrial setting at SCHOTT AG. Ultrashort pulsed (USP) lasers with a maximum average power of 220 W provided the opportunity to measure X-ray emissions at laser peak intensities of up to 3.3 × 1015 W/cm2 at pulse durations of ~1 ps. The results indicate that increasing the laser peak intensity is insufficient to generate high dose rates. The investigations were affected by various constraints which prevented measuring high ambient dose rates. In this work, a list of issues which may be encountered when performing measurements at USP-laser machines in industrial settings is identified.

scholarly journals Quest for the Upcoming Periastron Passage of an Episodic Dust Maker and Particle-accelerating Colliding-wind Binary: WR 125

2021 ◽  
Vol 162 (6) ◽  
pp. 257
Author(s):  
Bharti Arora ◽  
J. C. Pandey ◽  
Michaël De Becker ◽  
S. B. Pandey ◽  
Nand K. Chakradhari ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Recurrence Time ◽  
Time Interval ◽  
Wide Field ◽  
X Rays ◽  
Optical Telescope ◽  
X Ray ◽  
Enhanced Absorption

Abstract We have carried out a long-term infrared and X-ray investigation of the colliding-wind binary WR 125 (WC7 + O9III). The source was monitored using AstroSat Soft X-ray Telescope and the Tata Institute of Fundamental Research Near Infrared Imaging Camera-II mounted at the back of 3.6 m Devasthal Optical Telescope. WR 125 appeared brighter in the near-infrared K-band during the years 2017–2021 which is attributed to another episode of dust formation similar to the one reported during the likely periastron passage at the beginning of the 1990s. This is further supported by enhanced emission observed in the W1 and W2 bands of Wide-field Infrared Survey Explorer from 2018–2019. By combining archival X-ray data sets with our new measurements, long-term variations have been noticed. The source reaches a lower emission state in 2020 June (close to the recent infrared maximum) which could be due to enhanced absorption of X-rays produced in the colliding-wind region by the WC stellar wind close to the periastron in an eccentric orbit. The time interval between the previous and latest X-ray low states may indicate an orbital period of 28–29 years, in fair agreement with the recurrence time of episodic dust production. We also discuss published radio measurements in the context of a common picture based on a long-period binary scenario. These results allow us to draw relevant guidelines for future multiwavelength observations of WR 125.

scholarly journals Der Energiegewinn von Elektronen und die durch sie erzeugte harte Röntgen-Strahlung bei Thetapinch-Entladungen vor der Zündung

1962 ◽  
Vol 17 (11) ◽  
pp. 977-989
Author(s):  
R. Chodura ◽  
M. Keilhacker
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Energy Distribution ◽  
Charged Particles ◽  
Zero Magnetic Field ◽  
Time Interval ◽  
Spatial Distributions ◽  
X Rays ◽  
X Ray ◽  
The Magnetic Field

The following article deals with measurements on hard X-rays produced in thetapinch discharges before breakdown of the gas which often last for several halfcycles of the magnetic field. In order to explain the timedependent intensity and energy of the X-rays, at first two possible spatial distributions of the electric field in a thetapinch-coil are discussed and the gain of energy of charged particles is calculated. The calculation shows that the adiabatic invariant μ = m2 ν2/(2 mo Β) which gives the gain of energy as a function of the magnetic field Β is proportional to (| ω̇g ½to)—3 where ω̇g is the time-derivative of the gyrofrequency which is assumed to be constant and to is the time between zero magnetic field and the start of the particle. Therefore the hard X-rays can be produced only by electrons which were existing in a small time interval around zero magnetic field of the order |ω̇g|–½. Because of the dependence of µ on the initial position of the particle the elecrtons have an energy distribution which is calculated under the assumption that all electrons are uniformely distributed initially over the cross-section of the coil.From the measured time dependence of X-ray intensity the spatial distribution of the electric field in halfcycles before breakdown can be infered. The ratio of the X-ray intensities with and without absorbers has been measured for different values of the timedependent magnetic field and also for different steady bias magnetic fields by which the starting conditions (to) of the particles are altered. These ratios are in good agreement with corresponding theoretical values which are derived from the calculated energy distribution of the electrons. The experimental results show that in halfcycles before breakdown there exist different spatial distributions of the electric field depending on the rising density of charged particles.

Sign in / Sign up

Export Citation Format

Share Document