Calculation of the Neutron Parameters for Accelerator-Driven Subcritical Reactors

In this paper, the accelerator-driven subcritical reactor (ADSR) is simulated based on structure of the TRIGA-Mark II reactor. A proton beam is accelerated and interacts on the lead target. Two cases of using lead are considered here: firstly, solid lead is referred to as spallation neutron target and water as the coolant; secondly, molten lead is considered both as a target and as a coolant. The proton beam in the energy range from 115 MeV to 2000 MeV interacts with the lead to create neutrons. The neutron parameters as neutron yield Yn/p, neutron multiplication factor k, the radial and axial distributions of the neutron flux in the core have been calculated by using MCNPX program. The results show that the neutron yield increases as the energies of the proton beam increases. When using the lead target, the differences between the neutron yield are from 4.2% to 14.2% depending on the energies of the proton beam. The proportion of uranium in the mixtures should be around 24% to produce an effective neutron multiplier factor greater than 0.9. The neutron fluxes are much higher than the same calculations for the TRIGA-Mark II reactor model using tungsten target and light water coolant.

Identifying Senescent Cells That Drive Aging

Cellular senescence is a potent tumor suppressor mechanism. However, the untoward effect is that the accumulation of senescent cells promotes loss of resilience, aging and age-related diseases. One approach to maintaining the benefits of senescence while preventing the negative consequences is senolytic therapies: drugs that do not prevent senescence, but selectively kill senescent cells. Since virtually any type of cell can become senescent, it is important to identify the lineages of senescent cells that are most potent at driving loss of tissue homeostasis and aging. This will enable honing development of senolytics. We used a genetic approach to drive increased genotoxic stress, a potent inducer of senescence, in a tissue specific manner. The impact of this targeted senescence on different organs and cell types will be discussed, identifying a lead target for senolytics.

Lead evaporation by VUV radiation of various spectral ranges

The results of an experimental study of the plasma formed by the evaporation of the lead target in the field of powerful broadband VUV radiation are presented. A pulse light-erosion magnetoplasma compressor (MPC’s) discharge is used as a model source of VUV radiation. “Gas filtration” of radiation is used to control the spectral composition – the discharge takes place in pure inert gases: in argon at 200 torr and neon at 400 torr. This allows us to manage the spectral distribution of radiation energy and to limit the energy of quants which irradiate the lead target with the first ionization potential of buffer gas. Shadow photography, toeplergrathy, double exposure laser holographic interferometry are used for diagnostics. Experimentally established different distribution of parameters in the lead plasma depending on the spectral composition of the impact radiation (the composition of buffer gas). It is shown that when the energy of quants increases (above the lead second ionization potential), a more even heating of the plasma layer is realized.

Synthesis and Antibacterial Activities of Amidine Substituted Monocyclic β-Lactams

Background: Mononcyclic β-lactams are regarded as the most resistant class of β-lactams against a series of β-lactamases though possess limited antibacterial activity. Aztreonam being the first clinically approved monobactam needs broad-spectrum efficacy through structural modification. Objective: We strive to synthesize a number of monocyclic β-lactams by varying the substituents at N1, C3 and C4 positions of azetidinone ring and study the antimicrobial effect on variable bacterial strains. Methods: Seven new monobactam derivatives 23a-g, containing substituted-amidine moieties linked to the azetidinone ring via thiazole linker, were synthesized through multistep synthesis. The final compounds were investigated for their in vitro antibacterial activities using broth microdilution method, against ten bacterial strains of clinical interest. The minimum inhibitory concentrations (MICs) of newly synthesized derivatives were compared with aztreonam, ceftazidime and meropenem, existing clinical antibiotics. Results: All compounds 23a-g showed higher antibacterial activities (MIC 0.25 µg/mL to 64 µg/mL) against tested strains as compared to aztreonam (MIC 16 µg/mL to >64 µg/mL) and ceftazidime (MIC >64 µg/mL). However all compounds, except 23d, exhibited lower antibacterial activity against all tested bacterial strains as compared to meropenem. Conclusion: Compound 23d showed comparable or improved antibacterial activity (MIC 0.25 µg/mL to 2 µg/mL) to meropenem (MIC 1 µg/mL to 2 µg/mL) in case of seven bacterial species. Therefore, compound 23d may be valuable lead target for further investigations against multi-drug resistant Gram-negative bacteria.

OPERA tau neutrino charged current interactions

The OPERA experiment was designed to discover the vτ appearance in a vμ beam, due to neutrino oscillations. The detector, located in the underground Gran Sasso Laboratory, consisted of a nuclear photographic emulsion/lead target with a mass of about 1.25 kt, complemented by electronic detectors. It was exposed from 2008 to 2012 to the CNGS beam: an almost pure vμ beam with a baseline of 730 km, collecting a total of 1.8·1020 protons on target. The OPERA Collaboration eventually assessed the discovery of vμ→vτ oscillations with a statistical significance of 6.1 σ by observing ten vτ CC interaction candidates. These events have been published on the Open Data Portal at CERN. This paper provides a detailed description of the vτ data sample to make it usable by the whole community.

Structure Activity Design, Synthesis and Biological Activity of Newer Imidazole-Triazine Clubbed Derivative as Antimicrobial and Antitubercular Agents

Background: Imidazole and triazine derivatives act as antimicrobial and antitubercular agents. 2D-QSAR determination estimates the pharmacological activity on the basis of thermodynamic properties of the structure. Objective: The structural arrangements and thermodynamic properties of the imidazole derivatives are necessary for the enhancement of pharmacological activity. So imidazole-triazine clubbed derivatives were designed on the bases of molecular modeling 2D-QSAR study of antitubercular activity. Methods: PLSR method was applied for 2D-QSAR determination of the (Z)-5-ethylidene-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-2-phenyl-3,5-dihydro-4H-imidazol-4-one (B1-B10). The designed compounds were synthesized and spectrally evicted by IR, 1H NMR, 13C NMR, Mass spectra data as well as biologically screened opposite different antitubercular and antimicrobial species. Result: Compounds B4, B6, B7 were founds potent against different antimicrobial species. Compound B3 was more effective against M. tuberculosis H37Rv. Statistically significant QSAR model generated by PLSR methods shows external r2=0.9775 and internal q2=0.2798 predictive ability. Whereas, the model incorporates with three parameters PolarSurfaceAreaExcluding P and S, MomInertiaY and SsCH3count with their corresponding values for each molecule. Conclusion: 2D-QSAR study advised antitubercular activity directly proportional to total surface area of the polar atoms having molecules and moment of inertia on Y-axis. Whereas, inversely proportional to methyl group joined with single bond. The present study afforded favorable results which were further used to generate lead target molecules.

The major achievements of the OPERA experiment and its legacy

The OPERA experiment was designed to discover the [Formula: see text] appearance in a pure [Formula: see text] beam, resulting from neutrino oscillations. The detector, located in the underground Gran Sasso Laboratory, consisted of an emulsion/lead target complemented by electronic detectors and was exposed, from 2008 to 2012, to the (CERN Neutrinos to Gran Sasso (CNGS)) beam, an almost pure [Formula: see text] beam with a baseline of 730 km, collecting a total of [Formula: see text] protons on target. OPERA was unique in its capability of detecting all three neutrino flavors. OPERA discovered [Formula: see text] oscillations in appearance mode with a significance of [Formula: see text]. In this review, we report the major achievements of the OPERA experiment and its legacy in the nuclear emulsion technology.