Radiation resistance

The safety of irradiated pork packed in 25% CO2:75% N2 and stored at abuse temperature (10 or 15°C) was assessed by inoculation studies involving Salmonella typhimurium, Listeria monocytogenes, Escherichia coli, Yersinia enterocolitica and Clostridium perfringens. Irradiation to a dose of 1.75 kGy reduced pathogen numbers to below the detection limit of 102 cells g-1. When higher inoculum levels were used (106 cells g-1) irradiation at 1.75 kGy reduced pathogen numbers by 1 –>5 log10 cycles depending on strain. Clostridium perfringens was the most resistant, and Y. enterocolitica the most sensitive of the pathogens studied.In all cases when high numbers (106 to 107g-1) of spoilage and/or pathogenic bacteria were present initially on the pork the meat appeared spoiled, and although irradiation reduced the number of microorganisms, the meat was still unacceptable from a sensory viewpoint after treatment.It was concluded that the microbiological safety of irradiated, modified atmosp...

Cancer stem cells (CSCs) refer to a subset of tumor cells with the potential to self-renew and differentiate into different cancer subtypes, including leukemias and solid tumors. Dysregulated gene expression and alteration of critical signaling pathways have been observed in CSCs, compared to low-tumorigenic bulk tumor cells. CSCs are thought to be responsible for tumor onset, self-renewal/maintenance, recurrence, distant metastasis, angiogenesis, and drug/radiation resistance. In recent years, CSCs have attracted a great deal of attention due to the remarkable potential for the development of specific therapies targeting CSCs and the identification of key molecules that play a critical role in controlling the unique features of CSC-enriched populations. During the last several years, a tremendous amount of work has been done on developing new drugs and therapeutic products, such as small molecule inhibitors, antibodies, and
small interfering RNAs (siRNAs). These CSC-targeting agents selectively inhibit key components of various intrinsic signaling
pathways or specific cell surface markers of CSCs. Many novel therapeutic agents and new molecular targeting compounds have been tested, some of which are currently under investigation in preclinical and clinical trials. In this review
article, we provide an overview of the current status of the CSC hypothesis and discuss the various critical signaling pathways and specific cell surface markers involved in the development and maintenance of CSC populations. In addition, we also review various patents and CSC-targeting therapeutic strategies that may eventually lead to eradication of both bulk tumor cells and CSCs.

The effect of combining low-dose irradiation (1.75 kGy) with modified atmosphere packaging (MAP) on the microbiological and sensory quality of pork chops stored at refrigeration temperatures was studied. The microflora of irradiated MAP pork was almost exclusively composed of lactic acid bacteria, predominantly Lactobacillus spp. Modified atmospheres containing either 25 or 50% CO2, balance N2, resulted in the best microbial control in irradiated pork held at 4°C, compared to an unirradiated MAP control, and these atmospheres were subsequently used in sensory studies. The atmosphere containing 25% CO2 75% N2 maintained the uncooked colour and odour of irradiated pork chops more effectively than 50% CO2 50% N2. Therefore packaging in a modified atmosphere containing 25% CO2, balance N2, followed by irradiation to a dose of 1.75 kGy is recommended to improve the microbiological and sensory quality of pork chops.

Laser-produced plasmas (LPP) are laboratory-scale, table-top and high-brightness sources of partially coherent radiation that can be tuned between the extreme ultraviolet and the hard X-rays. A few LPP emission wavelengths find important applications in bio-photonics. As an example, LPP emitting in the so called “water window” (spectral range λ= 4.4 nm – 2.3 nm) allowed the world first X-ray scanning microscopy and contact microscopy, the latter being able to perform in vivo molecules imaging with 50-nm spatial resolution.

Radiation hardness is tested for 4H-SiC n-p-n bipo- lar junction transistors designed for 1200-V breakdown voltage by implanting MeV protons and carbon ions at different doses and energies. The current gain is found to be a very sensitive parameter, and a fluence as low as 1 × 107 cm−2 of 10 MeV 12C can be clearly detected in the forward-output characteristics, IC (VCE). At this low dose, no influence of ion radiation is seen in the open-collector characteristics, IB (VEB), or the reverse bias leakage and breakdown properties. Moreover, by annealing the implanted devices at 420 ◦C for 30 min, a complete recovery of the electrical characteristics is accomplished.

This paper introduces a modified enhanced transmission-line theory to account for higher-order modes while using a standard transmission line equation solver or equivalently a Baum, Liu and Tesche (BLT) equation solver. The complex per-unit-length parameters as defined by Nitsch et al. are first cast into an appropriate per-unit-length resistance, inductance, capacitance and conductance (RLCG) form. Besides, these per-unit-length parameters are modified to account for radiation losses with reasonable approximations. This modification is introduced by an additional per-unit-length resistance. The reason and explanations for this parameter are provided. Results obtained with this new formalism are comparable to those obtained using an electromagnetic full-wave solver, thus extending the capability of conventional transmission line solvers.

The work reported here represents a study into the total fluorescence exhibited by a broad selection of model, extremophilic and photosynthetic bacterial strains, over a great range of excitation and emission wavelengths from ultraviolet (UV) through visible to near infrared. The aim is to identify distinctive fluorescent features that may serve as detectable biosignatures of remnant microbial life on the Martian surface. A lab-bench fluorescence spectrometer was used to generate an excitation–emission matrix (EEM) for the unpigmented Escherichia coli, radiation-resistant Deinococcus radiodurans, Antarctic Dry Valley isolates Brevundimonas sp. MV.7 and Rhodococcus sp. MV.10, and the cyanobacterium Synechocystis sp. PCC 6803. Detailed EEMs, representing the fluorescence signature of each organism, are presented, and the most significant features suitable for biosignature surveys are identified, including small-molecule cellular metabolites, light-harvesting photosynthetic pigments an...

In this study, the mechanism for the unique minority-carrier injection-enhanced annealing phenomena and the origin of the major radiation-induced defect in InGaP top cell materials are discussed in comparison with InP. The optimal design for the InGaP base layer thickness of the InGaP/GaAs 2-junction cells for current matching at EOL is examined. It is also found that the radiation tolerance of InGaP/middle cell/Ge 3-junction tandem solar cells can be improved by thinning the InGaP top cell layer thickness, by reducing base layer carrier concentration of the GaAs bottom cells, and by looking for radiation-resistant middle cell materials.

Blending cyanate ester (CE) with epoxy resins offers the possibility to manufacture radiation resistant insulations at a low price compared to pure CE materials. Therefore, it is of special interest to study the influence of the CE content and also the effect of catalyst on the curing ...

(Accepted: 5 May 2004) Abstract. To assess the impact of UV-B radiation combined with NaHSO3 in solution under lab-oratory conditions, we compared the amounts of stress-ethylene produced by two lichen species of the same genus. Ramalina lacera, an epiphytic Mediterranean ...

A novel method of using artificial neural networks (ANNS) for the calculation of the radiation resistance of a coax-fed rectangular microstrip antenna is presented in this Letter. The network is trained with the results of three different antennas and tested for the fourth antenna. The tested results are in very good agreement. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 51–53, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10370

Electron microscopic studies of polymers are limited due to beam damage. Two concerns are the damage mechanism in a particular material, and the maximum dose for a material before damage effects are observed. From the knowledge of the dose required for damage to the ...

Electrically-small antennas present high-Q impedances characterized by large reactances and small radiation resistances. For such antennas, the effectiveness of passive matching is severely limited by gain-bandwidth theory, which predicts narrow bandwidths and/or poor gain. With receivers, the inability to resolve this impedance mismatch results in poor signal-to-noise (S/N) ratio, as compared to using a full-size antenna. With transmitters, the consequence

Glioblastoma multiforme (GBM) is a highly invasive primary brain tumour that has poor prognosis despite aggressive treatment. A hallmark of these tumours is diffuse invasion into the surrounding brain, necessitating a multi-modal treatment approach, including surgery, radiation and chemotherapy. We have previously demonstrated the ability of our model to predict radiographic response immediately following radiation therapy in individual GBM patients using a simplified geometry of the brain and theoretical radiation dose. Using only two pre-treatment magnetic resonance imaging scans, we calculate net rates of proliferation and invasion as well as radiation sensitivity for a patient's disease. Here, we present the application of our clinically targeted modelling approach to a single glioblastoma patient as a demonstration of our method. We apply our model in the full three-dimensional architecture of the brain to quantify the effects of regional resistance to radiation owing to hy...

... current in each sub-cell as a function of 1 MeV electron fluence; the ... the open symbols represent a lightweight panel technology where the cell weight is the dominant factor ... In a mechanical stackconfiguration, an In0448Ga0452P/GaAs/In0453Ga0447 As device holds the world ...

A new theoretical model is presented in which the radiation-induced zero-resistance states and resistivity oscillations are analyzed. The basis of our model is an exact solution for the harmonic oscillator wave function in the presence of radiation and a perturbation treatment for elastic scattering due to randomly distributed charged impurities. Following this model most experimental results are reproduced: zero-resistance states, resistivity oscillations and the dependence of resistivity with temperature, where a physical model of interaction with acoustic phonon is presented, and an activation energy is calculated.