A novel barium oxide-based Iraqi sand glass to attenuate the low gamma-ray energies: Fabrication, mechanical, and radiation protection capacity evaluation

Al-Saeedi F.H.F.,Sayyed M.I.,Kapustin F.L.,Al-Ghamdi Hanan,Kolobkova E.V.,Tashlykov O.L.,Almuqrin Aljawhara H.,Mahmoud K.A. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

In the present work, untreated Iraqi sand with grain sizes varied between 100 and 200 mm was used to produce a colored glass sample that has shielding features against the low gamma-ray energy. Therefore, a weight of 70e60 wt % sand was mixed with 9e14 wt% B2O3, 8e10 wt% Na2O, 4e6 wt% of CaO, 3e6 wt% Al2O3, in addition to 0.3% of Co2O3. After melting and annealing the glass sample, the X-ray diffraction spectrometry was applied to affirm the amorphous phase of the fabricated glass samples. Moreover, the X-ray dispersive energy spectrometry was used to measure the chemical composition, and the MH-300A densimeter was applied to measure the fabricated sample's density. The Makishima-Makinzie model was applied to predict the mechanical properties of the fabricated glass. Besides, the Monte Carlo simulation was used to estimate the fabricated glass sample's radiation shielding capacity in the low-energy region between 22.1 and 160.6 keV. Therefore, the simulated linear attenuation coefficient changed between 10.725 and 0.484 cm1 , raising the gamma-ray energy between 22.1 and 160.6 keV. Also, other shielding parameters such as a half-value layer, pure lead equivalent thickness, and buildup factors were calculated

Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2) from in situ and air archive observations

Simmonds, P. G.,Rigby, M.,Manning, A. J.,Lunt, M. F.,O&,apos,Doherty, S.,McCulloch, A.,Fraser, P. J.,Henne, S.,Vollmer, M. K.,Mü,hle, J.,Weiss, R. F.,Salameh, P. K.,Young, D.,Reimann, S.,Wenger Copernicus GmbH 2016 Atmospheric Chemistry and Physics Vol.16 No.1

<P>Abstract. High frequency, in situ observations from 11 globally distributed sites for the period 1994-2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1-difluoroethane (HFC-152a, CH3CHF2). These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a top-down approach. HFC-152a is a greenhouse gas with a short atmospheric lifetime of about 1.5 years. Since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The concentration of HFC-152a has grown substantially since the first direct measurements in 1994, reaching a maximum annual global growth rate of 0.84 ± 0.05 ppt yr−1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annual rate of growth has slowed to 0.38 ± 0.04 ppt yr−1 in 2010 with a further decline to an annual average rate of growth in 2013-2014 of −0.06 ± 0.05 ppt yr−1. The annual average Northern Hemisphere (NH) mole fraction in 1994 was 1.2 ppt rising to an annual average mole fraction of 10.1 ppt in 2014. Average annual mole fractions in the Southern Hemisphere (SH) in 1998 and 2014 were 0.84 and 4.5 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3 ± 5.6 Gg yr−1 in 1994 to a maximum of 54.4 ± 17.1 Gg yr−1 in 2011, declining to 52.5 ± 20.1 Gg yr−1 in 2014 or 7.2 ± 2.8 Tg-CO2 eq yr−1. Analysis of mole fraction enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia, and Europe. Global HFC emissions (so called “bottom up” emissions) reported by the United Nations Framework Convention on Climate Change (UNFCCC) are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There appears to be a significant underestimate ( > 20 Gg) of “bottom-up” reported emissions of HFC-152a, possibly arising from largely underestimated USA emissions and undeclared Asian emissions. </P>

Anti-Trypanosoma and toxicity potential of the extracts of Acacia nilotica, Bombax buonopozense and Khaya senegalensis

Sulaiman F. A.,Iyiola O. A.,Anifowoshe T. A.,Sulaiman A. A.,Bello O. K.,Akinyele T. J.,Jimoh A. M.,Maimako R. F.,Otohinoyi D. A.,Osemwegie O. O.,Adeyemi O. S. 경희대학교 융합한의과학연구소 2021 Oriental Pharmacy and Experimental Medicine Vol.21 No.1

The Trypanosoma brucei is the causative agent of African trypanosomiasis, a disease that affects both humans and animals. Chemotherapy which forms the major means of control for the disease has several shortcomings such as limited efficacy and adverse side effects amongst others. Thus, motivating the search for better therapies. In this study, extracts of some tropical plants including the Acacia nilotica, Bombax buonopozense and Khaya senegalensis were evaluated for therapeutic and prophylactic potential in mouse model of experimental trypanosomiasis. Both diminazene aceturate and isometamidium chloride were included as reference drugs. Results showed that T. brucei caused an elevation in rat plasma indirect bilirubin and a reduction in rat plasma albumin and total protein which suggest mild hepatic dysfunction due to experimental infection. Data also revealed that the plant extracts significantly reduced the rat parasite burden both in the prophylaxis and therapeutic treatment groups when compared with the negative drug control. The infection and treatments had no adverse effect on the rat organ and body weights. The infection did not alter the activity of rat plasma ALT, AST and ALP compared with the administered extracts of A. nilotica and B. buonopozense. Further, the plant extracts ameliorated some trypanosomiasisinduced pathologies in treated rats compared with negative drug control. Taken together, findings do not only lend credence to the folkloric use of these plants for medicinal purposes but also suggest these plant extracts have potential to serve as alternative source of anti-parasitic agents particularly for the control of trypanosomiasis

The Amazon Tall Tower Observatory (ATTO): overview of pilot measurements on ecosystem ecology, meteorology, trace gases, and aerosols

Andreae, M. O.,Acevedo, O. C.,Araù,jo, A.,Artaxo, P.,Barbosa, C. G. G.,Barbosa, H. M. J.,Brito, J.,Carbone, S.,Chi, X.,Cintra, B. B. L.,da Silva, N. F.,Dias, N. L.,Dias-Jú,nior, C. Q.,Dita Copernicus GmbH 2015 Atmospheric Chemistry and Physics Vol.15 No.18

<P>Abstract. The Amazon Basin plays key roles in the carbon and water cycles, climate change, atmospheric chemistry, and biodiversity. It has already been changed significantly by human activities, and more pervasive change is expected to occur in the coming decades. It is therefore essential to establish long-term measurement sites that provide a baseline record of present-day climatic, biogeochemical, and atmospheric conditions and that will be operated over coming decades to monitor change in the Amazon region, as human perturbations increase in the future. The Amazon Tall Tower Observatory (ATTO) has been set up in a pristine rain forest region in the central Amazon Basin, about 150 km northeast of the city of Manaus. Two 80 m towers have been operated at the site since 2012, and a 325 m tower is nearing completion in mid-2015. An ecological survey including a biodiversity assessment has been conducted in the forest region surrounding the site. Measurements of micrometeorological and atmospheric chemical variables were initiated in 2012, and their range has continued to broaden over the last few years. The meteorological and micrometeorological measurements include temperature and wind profiles, precipitation, water and energy fluxes, turbulence components, soil temperature profiles and soil heat fluxes, radiation fluxes, and visibility. A tree has been instrumented to measure stem profiles of temperature, light intensity, and water content in cryptogamic covers. The trace gas measurements comprise continuous monitoring of carbon dioxide, carbon monoxide, methane, and ozone at five to eight different heights, complemented by a variety of additional species measured during intensive campaigns (e.g., VOC, NO, NO2, and OH reactivity). Aerosol optical, microphysical, and chemical measurements are being made above the canopy as well as in the canopy space. They include aerosol light scattering and absorption, fluorescence, number and volume size distributions, chemical composition, cloud condensation nuclei (CCN) concentrations, and hygroscopicity. In this paper, we discuss the scientific context of the ATTO observatory and present an overview of results from ecological, meteorological, and chemical pilot studies at the ATTO site. </P>

Engrailed homeoprotein recruits the adenosine A1 receptor to potentiate ephrin A5 function in retinal growth cones

Stettler, O.,Joshi, R. L.,Wizenmann, A.,Reingruber, J.,Holcman, D.,Bouillot, C.,Castagner, F.,Prochiantz, A.,Moya, K. L. The Company of Biologists 2012 Development (Cambridge) Vol.139 No.1

<P>Engrailed 1 and engrailed 2 homeoprotein transcription factors (collectively Engrailed) display graded expression in the chick optic tectum where they participate in retino-tectal patterning. In vitro, extracellular Engrailed guides retinal ganglion cell (RGC) axons and synergises with ephrin A5 to provoke the collapse of temporal growth cones. In vivo disruption of endogenous extracellular Engrailed leads to misrouting of RGC axons. Here we characterise the signalling pathway of extracellular Engrailed. Our results show that Engrailed/ephrin A5 synergy in growth cone collapse involves adenosine A1 receptor activation after Engrailed-dependent ATP synthesis, followed by ATP secretion and hydrolysis to adenosine. This is, to our knowledge, the first evidence for a role of the adenosine A1 receptor in axon guidance. Based on these results, together with higher expression of the adenosine A1 receptor in temporal than nasal growth cones, we propose a computational model that illustrates how the interaction between Engrailed, ephrin A5 and adenosine could increase the precision of the retinal projection map.</P>

First spin-parity constraint of the 306 keV resonance in Cl35 for nova nucleosynthesis

Chipps, K. A.,Pain, S. D.,Kozub, R. L.,Bardayan, D. W.,Cizewski, J. A.,Chae, K. Y.,Liang, J. F.,Matei, C.,Moazen, B. H.,Nesaraja, C. D.,O'Malley, P. D.,Peters, W. A.,Pittman, S. T.,Schmitt, K. T.,Smit American Physical Society 2017 Physical review. C Vol.95 No.4

<P>Of particular interest in astrophysics is the S-34(p,gamma) Cl-35 reaction, which serves as a stepping stone in thermonuclear runaway reaction chains during a nova explosion. Though the isotopes involved are all stable, the reaction rate of this significant step is not well known, due to a lack of experimental spectroscopic information on states within the Gamow window above the proton separation threshold of Cl-35. Measurements of level spins and parities provide input for the calculation of resonance strengths, which ultimately determine the astrophysical reaction rate of the S-34(p,gamma)Cl-35 proton capture reaction. By performing the Cl-37( p,t)Cl-35 reaction in normal kinematics at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory, we have conducted a study of the region of astrophysical interest in Cl-35, and have made the first-ever constraint on the spin and parity assignment for a level at 6677 +/- 15 keV (E-r = 306 keV), inside the Gamow window for novae.</P>

Criticality analysis of pyrochemical reprocessing apparatuses for mixed uranium-plutonium nitride spent nuclear fuel using the MCU-FR and MCNP program codes

Kizub P.A.,Blokhin A.I.,Blokhin P.A.,Mitenkova E.F.,Mosunova N.A.,Kovrov V.A.,Shishkin A.V.,Zaikov Yu.P.,Rakhmanova O.R. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

A preliminary criticality analysis for novel pyrochemical apparatuses for the reprocessing of mixed uranium-plutonium nitride spent nuclear fuel from the BREST-OD-300 reactor was performed. Hightemperature processing apparatuses, “metallization” electrolyzer, refinery remelting apparatus, refining electrolyzer, and “soft” chlorination apparatus are considered in this work. Computational models of apparatuses for two neutron radiation transport codes (MCU-FR and MCNP) were developed and calculations for criticality were completed using the Monte Carlo method. The criticality analysis was performed for different loads of fissile material into the apparatuses including overloading conditions. Various emergency situations were considered, in particular, those associated with water ingress into the chamber of the refinery remelting apparatus. It was revealed that for all the considered computational models nuclear safety rules are satisfied.

Single-particle characterization of aerosols collected at a remote site in the Amazonian rainforest and an urban site in Manaus, Brazil

Wu, Li,Li, Xue,Kim, HyeKyeong,Geng, Hong,Godoi, Ricardo H. M.,Barbosa, Cybelli G. G.,Godoi, Ana F. L.,Yamamoto, Carlos I.,de Souza, Rodrigo A. F.,Pö,hlker, Christopher,Andreae, Meinrat O.,Ro, Chul Copernicus GmbH 2019 Atmospheric chemistry and physics Vol.19 No.2

<P><p><strong>Abstract.</strong> <span id='page1222'/>In this study, aerosol samples collected at a remote site in the Amazonian rainforest and an urban site in Manaus, Brazil, were investigated on a single-particle basis using a quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA). A total of 23 aerosol samples were collected in four size ranges (0.25-0.5, 0.5-1.0, 1.0-2.0, and 2.0-4.0<span class='thinspace'></span><span class='inline-formula'>µ</span>m) during the wet season in 2012 at two Amazon basin sites: 10 samples in Manaus, an urban area; and 13 samples at an 80<span class='thinspace'></span>m high tower, located at the Amazon Tall Tower Observatory (ATTO) site in the middle of the rainforest, 150<span class='thinspace'></span>km northeast of Manaus. The aerosol particles were classified into nine particle types based on the morphology on the secondary electron images (SEIs) together with the elemental concentrations of 3162 individual particles: (i) secondary organic aerosols (SOA); (ii) ammonium sulfate (AS); (iii) SOA and AS mixtures; (iv) aged mineral dust; (v) reacted sea salts; (vi) primary biological aerosol (PBA); (vii) carbon-rich or elemental carbon (EC) particles, such as soot, tarball, and char; (viii) fly ash; and (ix) heavy metal (HM, such as Fe, Zn, Ni, and Ti)-containing particles. In submicron aerosols collected at the ATTO site, SOA and AS mixture particles were predominant (50<span class='thinspace'></span>%-94<span class='thinspace'></span>% in relative abundance) with SOA and ammonium sulfate comprising 73<span class='thinspace'></span>%-100<span class='thinspace'></span>%. In supermicron aerosols at the ATTO site, aged mineral dust and sea salts (37<span class='thinspace'></span>%-70<span class='thinspace'></span>%) as well as SOA and ammonium sulfate (28<span class='thinspace'></span>%-58<span class='thinspace'></span>%) were abundant. PBAs were observed abundantly in the PM<span class='inline-formula'>₂₋₄</span> fraction (46<span class='thinspace'></span>%), and EC and fly ash particles were absent in all size fractions. The analysis of a bulk PM<span class='inline-formula'>_0.25−0.5</span> aerosol sample from the ATTO site using Raman microspectrometry and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) showed that ammonium sulfate, organics, and minerals are the major chemical species, which is consistent with the ED-EPMA results. In the submicron aerosols collected in Manaus, either SOA and ammonium sulfate (17<span class='thinspace'></span>%-80<span class='thinspace'></span>%) or EC particles (6<span class='thinspace'></span>%-78<span class='thinspace'></span>%) were dominant depending on the samples. In contrast, aged mineral dust, reacted sea salt, PBA, SOA, ammonium sulfate, and EC particles comprised most of the supermicron aerosols collected in Manaus. The SOA, ammonium sulfate, and PBAs were mostly of a biogenic origin from the rainforest, whereas the EC and HM-containing particles were of an anthropogenic origin. Based on the different contents of SOA, ammonium sulfate, and EC particles among the samples collected in Manaus, a considerable influence of the rainforest over the city was observed. Aged mineral dust and reacted sea-salt particles, including mineral dust mixed with sea salts probably during long-range transatlantic transport, were abundant in the supermicron fractions at both sites. Among the aged mineral dust and reacted sea-salt particles, sulfate-containing ones outnumbered those containing nitrates and sulfate<span class='thinspace'></span><span class='inline-formula'>+</span><span class='thinspace'></span>nitrate in the ATTO samples. In contrast, particles containing sulfate<span class='thinspace'></span><span class='inline-formula'>+</span><span class='thinspace'></span>nitrate were comparable in number to particles containing sulfate only in the Manaus samples, indicating

Strain Mismatch Induced Tilted Heteroepitaxial (000<i>l</i>) Hexagonal ZnO Films on (001) Cubic Substrates

Kang, Bo Soo,Stan, Liliana,Usov, Igor O.,Lee, Jung‐,Kun,Harriman, Tres A.,Lucca, Don A.,DePaula, Raymond F.,Arendt, Paul N.,Nastasi, Michael,MacManus‐,Driscoll, Judith L.,Park, Bae Ho,Jia, WILEY‐VCH Verlag 2011 Advanced Engineering Materials Vol.13 No.12

<P><B>Abstract</B></P><P>A novel strain mismatch induced tilted epitaxy method has been demonstrated for producing high quality (000l) hexagonal films on (001) cubic substrates. Highly oriented hexagonal (000l) ZnO films are grown on cubic (001) MgO substrates using Sm<SUB>0.28</SUB>Zr<SUB>0.72</SUB>O<SUB>2−<B>δ</B></SUB> (SZO) as a template. The large lattice mismatch of >13% between the obvious crystallographic matching directions of the template and substrate means that cube‐on‐cube epitaxy is energetically unfavorable, leading to growth instead of two high index, low energy compact planes, close to the {111} orientation. These planes give three different in‐plane orientations resulting from coincidence site lattice matching (12 in‐plane orientations in total) and provide a pseudo‐hexagonal symmetry surface for the ZnO to grow on. The texture of the ensuing (000l) ZnO layer is markedly improved over the template. The work opens up both a new avenue for growing technologically important hexagonal structures on a range of readily available, (001) cubic substrates, as well as showing that there are wide possibilities for heteroepitaxial growth of a range of dissimilar materials.</P>

Tandem Solar Cells from Solution-Processed CdTe and PbS Quantum Dots Using a ZnTe–ZnO Tunnel Junction

Crisp, Ryan W.,Pach, Gregory F.,Kurley, J. Matthew,France, Ryan M.,Reese, Matthew O.,Nanayakkara, Sanjini U.,MacLeod, Bradley A.,Talapin, Dmitri V.,Beard, Matthew C.,Luther, Joseph M. American Chemical Society 2017 Nano letters Vol.17 No.2

<P>We developed a monolithic CdTe–PbS tandem solar cell architecture in which both the CdTe and PbS absorber layers are solution-processed from nanocrystal inks. Due to their tunable nature, PbS quantum dots (QDs), with a controllable band gap between 0.4 and ∼1.6 eV, are a promising candidate for a bottom absorber layer in tandem photovoltaics. In the detailed balance limit, the ideal configuration of a CdTe (<I>E</I><SUB>g</SUB> = 1.5 eV)–PbS tandem structure assumes infinite thickness of the absorber layers and requires the PbS band gap to be 0.75 eV to theoretically achieve a power conversion efficiency (PCE) of 45%. However, modeling shows that by allowing the thickness of the CdTe layer to vary, a tandem with efficiency over 40% is achievable using bottom cell band gaps ranging from 0.68 and 1.16 eV. In a first step toward developing this technology, we explore CdTe–PbS tandem devices by developing a ZnTe–ZnO tunnel junction, which appropriately combines the two subcells in series. We examine the basic characteristics of the solar cells as a function of layer thickness and bottom-cell band gap and demonstrate open-circuit voltages in excess of 1.1 V with matched short circuit current density of 10 mA/cm<SUP>2</SUP> in prototype devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2017/nalefd.2017.17.issue-2/acs.nanolett.6b04423/production/images/medium/nl-2016-04423k_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl6b04423'>ACS Electronic Supporting Info</A></P>