An effort to enhance the threshold contrast index of gas Cherenkov detectors

Because of being capable of excluding the most of secondary gamma rays interference, gas Cherenkov detectors have been the primary candidate for fusion gamma rays detection. It is a goal worthy of long-term efforts to enhance the threshold contrast index used for evaluating the ability of GCD to exclude below-threshold interference. The paper presents the way of enhancing the index through ultraviolet reflection selective suppression of scintillation signal in the detectors. Both theoretical estimation and experimental verification demonstrate that the threshold contrast index can be enhanced by 5.5 times after applying this method. This provides possibilities of obtaining better fusion gamma rays detection waveforms and higher confidence diagnostic information.

Leukocyte composition of pronephros of Leocottus kesslerii infected with hemoflagellates of the genus Trypanosoma (Kinetoplastea: Trypanosomatida)

This study determined for the first time the changes in leukocyte composition of the pronephros (head kidney) of sand sculpin Leocottus kesslerii, (Sideleva, 2001) (Lake Gusinoye, Lake Baikal basin, Eastern Siberia, Russia), infected and uninfected with hemoflaggellates of the genus Trypanosoma. The results indicated that the trypanosomes modulated the development of the immune response of their host (suppression of B cell immunity and granulocytic reactions, activation of the leucopoiesis and monocytopoiesis). Selective suppression of immune response in host with trypanosomes promotes the survival and development of parasites.

19F MRI Imaging Strategies to Reduce Isoflurane Artifacts in In Vivo Images

Purpose Isoflurane (ISO) is the most commonly used preclinical inhalation anesthetic. This is a problem in 19F MRI of fluorine contrast agents, as ISO signals cause artifacts that interfere with unambiguous image interpretation and quantification; the two most attractive properties of heteronuclear MRI. We aimed to avoid these artifacts using MRI strategies that can be applied by any pre-clinical researcher. Procedures Three strategies to avoid ISO chemical shift displacement artifacts (CSDA) in 19F MRI are described and demonstrated with measurements of 19F-containing agents in phantoms and in vivo (n = 3 for all strategies). The success of these strategies is compared to a standard Rapid Acquisition with Relaxation Enhancement (RARE) sequence, with phantom and in vivo validation. ISO artifacts can successfully be avoided by (1) shifting them outside the region of interest using a narrow signal acquisition bandwidth, (2) suppression of ISO by planning a frequency-selective suppression pulse before signal acquisition or by (3) preventing ISO excitation with a 3D sequence with a narrow excitation bandwidth. Results All three strategies result in complete ISO signal avoidance (p < 0.0001 for all methods). Using a narrow acquisition bandwidth can result in loss of signal to noise ratio and distortion of the image, and a frequency-selective suppression pulse can be incomplete when B1-inhomogeneities are present. Preventing ISO excitation with a narrow excitation pulse in a 3D sequence yields the most robust results (relative SNR 151 ± 28% compared to 2D multislice methods, p = 0.006). Conclusion We optimized three easily implementable methods to avoid ISO signal artifacts and validated their performance in phantoms and in vivo. We make recommendation on the parameters that pre-clinical studies should report in their method section to make the used approach insightful.

Selective Suppression of {112} Anatase Facet by Fluorination for Enhanced TiO2 Particle Size and Phase Stability at Elevated Temperatures

Generally, anatase is the most desirable TiO2 polymorphic phase for photovoltaic and photocatalytic applications due to its higher photoconductivity and lower recombination rates compared to rutile phase. However, in applications...