5,858 research outputs found
Metallic impurities in the Cu-fraction of Ni targets prepared from NiCl2 solutions
Introduction
Copper-64 is an emerging radionuclide with applications in PET molecular imaging and/or internal therapy and it is typically produced by proton irradiation of isotopically enriched 64Ni electrodeposited on a suitable backing substrate. We recently reported a simple and efficient method for the preparation of nickel targets from electrolytic solutions of nickel chloride and boric acid [1]. Herein we report our recent research work on the analysis of metallic impurities in the copper-fraction of the radiochemical separation process.
Material and Methods
Nickel targets were prepared and processed as previously reported [1]. Briefly, the bath solution was composed of a mixture of natural NiCl2. 6H2O (135 mg/ml) and H3BO3 (15 mg/ml) and Ni was electrodeposited using a gold disk as cathode and a platinum wire as anode. The plating process was carried out at room temperature using 2 ml of bath solution (pH = 3.7) and a constant current density of 60 mA/cm2 for 1 hour. The unirradiated Ni targets were dissolved in 1–2 ml of concentrated (10M) HCl at 90 oC. After complete dissolution of the Ni layer, water was added to dilute the acid to 6M, and the solution was transferred onto a chromatographic column containing AG 1-X8 resin equilibrated with 6M HCl. The Ni , Co and Cu isotopes were separated by using the well-known chromatography of the chloro-complexes. The sample-fractions containing the Cu isotopes (15 ml, 0.1M HCl) were collected in plastic centrifuge tubes previously soaked in 1M HNO3 and rinsed with Milli-Q water (18 MΩ cm). Impurities of B, Co, Ni, Cu and Zn in these samples were determined by inductively coupled plasma-mass spectroscopy (ICP-MS) at the Department of Geosciences (Laboratory of Isotopic Studies) of the National University.
Results and Conclusions
The mass of Ni deposited in 1 h was 25.0 ± 1.0 mg (n = 3) and the current efficiency was > 75 % in all cases. The pH of the electrolytic solution tended to decrease along the electrodeposition process (3.71.6). The results of ICP-MS analysis of the Cu-fractions from the cold chromatography separation runs are shown in FIG. 1. We were particularly interested in the boron impurities as H3BO3 is used as buffer for electrodeposition of the Ni targets.
Except for the Ni impurities that were deter-mined to be in the range of ppm (mg/l), all other analyzed metallic impurities were found to be in the range of ppb (µg/l), including boron. The Co, Ni, Cu and Zn impurities determined in the Cu-fraction in this work using Ni targets electrode-posited from a NiCl2 acidic solution, are in the same order of magnitude compared with that obtained when using targets prepared from an alkaline solution [2], with the advantage of the simplicity of the electrodeposition method from NiCl2 solutions, as the target material is already recovered in the chemical form of NiCl2, enabling a simpler, one step process to prepare a new plating solution when using enriched 64Ni target material for the production of 64Cu
Insulin Resistance and Obesity in Mexican Youth
Purpose: Although research shows that prevalence rates of insulin resistance (IR) is increasing in children, little is known about the impact of obesity in IR in Mexican youth. This study investigated the association between overweight, obesity, and insulin resistance in Mexican adolescents. Methods: Data were collected from 448 adolescents aged 12 to 18 years from a random sample of a high school student population in Durango, Mexico. After fasting overnight, blood samples were obtained from participants. Glucose, insulin, lipid profile, leptin, insulin growth factor, growth hormone, cortisol, TNF-alpha, and C-reactive protein were determined in serum. Body Mass Index (BMI) was calculated using CDC parameters. Fat mass was determined using a bioelectrical impedance analyzer. THE HOMA index was used to calculate IR and a Keskin diagnosis value of 3.1 was considered. Statistical analyses were conducted.
Results: The mean age of the sample was 15.44 years and a majority was female (61.4%). Prevalence of overweight and obesity was 31.9%. The BMI mean was slightly higher in females (65.5) than in males (61.1) (p \u3e0.05). Females had a greater mean of body fat percentage (31.9) than males (20.2) (p\u3c 0.05). Prevalence of resistance to insulin by HOMA-IR was 14.4% with no statistically significant gender differences. The IR mean was higher in adolescents with greater BMI (≥85th percentile) than those with low and normal BMI (\u3c85th percentile) (p \u3c0.05). Adolescents with high IR levels (≥3.1) had higher mean values of corporal fat (37.69%) and BMI (89.76) than those with lower IR levels (\u3c3.1) and lower corporal fat and BMI values (26.4%3 and 61.67, respectively). Conclusions: The significant association found between obesity and insulin resistance in Mexican adolescents suggests a greater risk for the development of degenerative disease in this young population during adulthood. Public health programs among Mexican adolescents are essential to prevent obesity and IR related consequences
P07-05. HIV and STI prevalence among men who have sex with men (MSM) recruited through respondent driven sampling (RDS) in Buenos Aires, Argentina
Fil: Pando, María A. Centro Nacional de Referencia para el SIDA; Argentina.Fil: Marone, Rubén. Nexo Asociación Civil; Argentina.Fil: Balán, Iván C. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Dolezal, Curtis. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Squiquera, Luis. Nexo Asociación Civil; Argentina. Fil: Balan, Iván C. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Picconi, María Alejandra. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Servicio Virus Oncogénicos; Argentina.Fil: Gonzales, J. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Servicio Virus Oncogénicos; Argentina.Fil: Rey, Jorge. Hospital de Clínicas José de San Martín; Argentina.Fil: Fernandez Toscano, M. Hospital de Clínicas José de San Martín; Argentina.Fil: Rodriguez Fermepín, Marcelo. UBA. Laboratorio de Inmunología Clínica; Argentina.Fil: Gallo Vaulet, Lucia. UBA. Laboratorio de Inmunología Clínica; Argentina.Fil: Carballo Dieguez, Alex. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Avila, María M. Centro Nacional de Referencia para el SIDA; Argentina.Background
MSM constitute one of the populations most affected by HIV and other STIs in Argentina. Previous prevalence studies were based on convenience samples. RDS, a methodology designed to access hidden populations, is being used for the first time in Argentina to recruit MSM.
Methods
RDS recruitment started in November 2007 with 16 first generation participants (seeds) who were selected for their potential to tap in MSM networks. Recruitment is ongoing. Men must be 18 years of age or older, be residents of Buenos Aires, self-report having sex with men at least 10 times in their lives and at least once in the past six months. They must have a coupon indicating they have been referred by a study participant. Specimens are being collected for HIV and STI diagnosis. All data are weighted using the RDS Analysis Tool (RDSAT).
Results
To date, 333 MSM were recruited through RDS showing a prevalence of 11.3, 16.6, 7.9, 17.6, 4.0 and 88.3% for HIV, HBV, HCV, T. pallidum, Chlamydia and HPV, respectively. Chlamydia and HPV diagnoses were only performed in 73 and 79 participants, respectively. Among HPV positive individuals, 47.8% had almost one of these high risk types (16, 58, 33, 45, 18 and 31) and 32% had multiple infections with 2 or more types.
Conclusion
Compared with previous studies, these results show similar HIV, HBV and T. pallidum prevalences but higher HCV prevalence. For the first time, an elevated prevalence of HPV was detected on MSM, with high frequency of types associated with ano-genital cancer. Preliminary analyses of socio demographic data show that RDS helps recruit a diversity of MSM, particularly of lower socio-economic level usually missed with other recruitment methods. The high prevalence of coinfections in this population should be taken into account if MSM are part of vaccine trials given that STI may increase HIV sexual transmission
The evolution of compact massive quiescent and star-forming galaxies derived from the Re–Rh and Mstar–Mh relations
The mean size (effective radius Re) of massive galaxies (MGs; Mstar > 1011.2M⊙) is observed to increase steadily with cosmic time. It is still unclear whether this trend originates from the size growth of individual galaxies (via, e.g. mergers and/or AGN feedback) or from the inclusion of larger galaxies entering the selection at later epochs (progenitor bias). We here build a data-driven, flexible theoretical framework to probe the structural evolution of MGs. We assign galaxies to dark matter haloes via stellar mass–halo mass (SMHM) relations with varying high-mass slopes and scatters σSMHM in stellar mass at fixed halo mass, and assign sizes to galaxies using an empirically motivated, constant and linear relationship between Re and the host dark matter halo radius Rh. We find that (1) the fast mean size growth of MGs is well reproduced independently of the shape of the input SMHM relation; (2) the numbers of compact MGs grow steadily until z ≳ 2 and fall off at lower redshifts, suggesting a lesser role of progenitor bias at later epochs; (3) a time-independent scatter σSMHM is consistent with a scenario in which compact star-forming MGs transition into quiescent MGs in a few 108 yr with a negligible structural evolution during the compact phase, while a scatter increasing at high redshift implies significant size growth during the star-forming phase. A robust measurement of the size function of MGs at high redshift can set strong constraints on the scatter of the SMHM relation and, by extension, on models of galaxy evolution
Contextual fear memory modulates PSD95 phosphorylation, AMPAr subunits, PKMζ and PI3K differentially between adult and juvenile rats
It is well known that young organisms do not maintain memories as long as adults, but the mechanisms for this ontogenetic difference are undetermined. Previous work has revealed that the α-amino-3-hydroxy-5-methyl-4isoxazolepropionic acidreceptor (AMPAr)subunits aretraffickedinto the synaptic membranefollowing memory retrieval in adults. Additionally, phosphorylated PSD-95-pS295 promotes AMPAr stabilization at the synapse. We investigated these plasticity related proteins as potential mediators in the differential contextual stress memory retrieval capabilities observed between adult and juvenile rats. Rats were assigned to either pedestal stress (1h) or no stress control (home cage). Each animal was placed alone in an open field for 5minat the base of a 6×6 sq inch pedestal (4ft high). Stress subjects were then placed on this pedestal for 1hr and control subjects were placed in their homecage following initial exploration. Each animal was returned to the open field for 5min either 1d or 7d following initial exposure. Freezing postures were quantified during the memory retrieval test. The 1d test shows adult (P90) and juvenile (P26) stressed rats increase their freezing time compared to controls. However, the 7d memory retrieval test shows P90 stress rats but not P26 stress rats freeze while in the fear context. Twenty minutes after the memory retrieval test, hippocampi and amygdala were micro-dissected and prepared for western blot analysis. Our results show that 1d fear memory retrieval induced an upregulation of PSD-95 and pS295 in the adult amygdala but not in the juvenile. However, the juvenile animals upregulated PKMζ, PI3K and GluA2/3, GluA1-S845 in the dorsal hippocampus (DH), but the adults did not. Following the 7d memory retrieval test, adults upregulated GluA2 in the amygdala but not the juveniles. In the DH, adults increased PSD-95 and pS295 but not the juveniles. The adults appear to preferentially increase amygdala-driven processing at 1d and increase DH-driven context specific processing at 7d. These data identify molecular processes that may underlie the reduced fear-memory retrieval capability of juveniles. Together these data provide a potential molecular target that could be beneficial in treatment of anxiety disorders and PTSD
Effect of Recombinant Prophenin 2 on the Integrity and Viability of Trichomonas vaginalis
Trichomonas vaginalis is the causal agent of trichomoniasis, which is associated with preterm child delivery, low birth weight, and an increased risk of infection by human papilloma virus and human immunodeficiency virus following exposure. Several reports have established increasing numbers of trichomoniasis cases resistant to metronidazole, the agent used for treatment, and it is therefore important to identify new therapeutic alternatives. Previously, our group reported the effect of tritrpticin, a synthetic peptide derived from porcine prophenin, on T. vaginalis; however, the hemolytic activity of this small peptide complicates its possible use as a therapeutic agent. In this study, we report that the propeptide and the processed peptide of prophenin 2 (cleaved with hydroxylamine) affected the integrity and growth of T. vaginalis and that pro-prophenin 2 displays some resistance to proteolysis by T. vaginalis proteinases at 1 h. Its effect on T. vaginalis as well as its low hemolytic activity and short-time stability to parasite proteinases makes prophenin 2 an interesting candidate for synergistic or alternative treatment against T. vaginalis
The Detection and Characterization of cm Radio Continuum Emission from the Low-mass Protostar L1014-IRS
Observations by the Cores to Disk Legacy Team with the Spitzer Space
Telescope have identified a low luminosity, mid-infrared source within the
dense core, Lynds 1014, which was previously thought to harbor no internal
source. Followup near-infrared and submillimeter interferometric observations
have confirmed the protostellar nature of this source by detecting scattered
light from an outflow cavity and a weak molecular outflow. In this paper, we
report the detection of cm continuum emission with the VLA. The emission is
characterized by a quiescent, unresolved 90 uJy 6 cm source within 0.2" of the
Spitzer source. The spectral index of the quiescent component is between 6 cm and 3.6 cm. A factor of two increase in 6 cm
emission was detected during one epoch and circular polarization was marginally
detected at the level with Stokes {V/I} % . We have
searched for 22 GHz H2O maser emission toward L1014-IRS, but no masers were
detected during 7 epochs of observations between June 2004 and December 2006.
L1014-IRS appears to be a low-mass, accreting protostar which exhibits cm
emission from a thermal jet or a wind, with a variable non-thermal emission
component. The quiescent cm radio emission is noticeably above the correlation
of 3.6 cm and 6 cm luminosity versus bolometric luminosity, indicating more
radio emission than expected. We characterize the cm continuum emission in
terms of observations of other low-mass protostars, including updated
correlations of centimeter continuum emission with bolometric luminosity and
outflow force, and discuss the implications of recent larger distance estimates
on the physical attributes of the protostar and dense molecular core.Comment: 14 pages. Accepted for publication in Ap
SSDSS IV MaNGA - Properties of AGN host galaxies
We present here the characterization of the main properties of a sample of 98
AGN host galaxies, both type-II and type-I, in comparison with those of about
2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts
are morphologically early-type or early-spirals. For a given morphology AGN
hosts are, in average, more massive, more compact, more central peaked and
rather pressurethan rotational-supported systems. We confirm previous results
indicating that AGN hosts are located in the intermediate/transition region
between star-forming and non-star-forming galaxies (i.e., the so-called green
valley), both in the ColorMagnitude and the star formation main sequence
diagrams. Taking into account their relative distribution in terms of the
stellar metallicity and oxygen gas abundance and a rough estimation of their
molecular gas content, we consider that these galaxies are in the process of
halting/quenching the star formation, in an actual transition between both
groups. The analysis of the radial distributions of the starformation rate,
specific star-formation rate, and molecular gas density shows that the
quenching happens from inside-out involving both a decrease of the efficiency
of the star formation and a deficit of molecular gas. All the intermediate
data-products used to derive the results of our analysis are distributed in a
database including the spatial distribution and average properties of the
stellar populations and ionized gas, published as a Sloan Digital Sky Survey
Value Added Catalog being part of the 14th Data Release:
http://www.sdss.org/dr14/manga/manga-data/manga-pipe3d-value-added-catalog/Comment: 48 pages, 14 figures, in press in RMxA
Testing main Amazonian rivers as barriers across time and space within widespread taxa
AimPresent Amazonian diversity patterns can result from many different mechanisms and, consequently, the factors contributing to divergence across regions and/or taxa may differ. Nevertheless, the riverâ barrier hypothesis is still widely invoked as a causal process in divergence of Amazonian species. Here we use modelâ based phylogeographic analyses to test the extent to which major Amazonian rivers act similarly as barriers across time and space in two broadly distributed Amazonian taxa.LocalAmazon rain forest.TaxonThe lizard Gonatodes humeralis (Sphaerodactylidae) and the tree frog Dendropsophus leucophyllatus (Hylidae).MethodsWe obtained RADseq data for samples distributed across main river barriers, representing main Areas of Endemism previously proposed for the region. We conduct modelâ based phylogeographic and genetic differentiation analyses across each population pair.ResultsMeasures of genetic differentiation (based on FST calculated from genomic data) show that all rivers are associated with significant genetic differentiation. Parameters estimated under investigated divergence models showed that divergence times for populations separated by each of the 11 bordering rivers were all fairly recent. The degree of differentiation consistently varied between taxa and among rivers, which is not an artifact of any corresponding difference in the genetic diversities of the respective taxa, or to amounts of migration based on analyses of the siteâ frequency spectrum.Main conclusionsTaken together, our results support a dispersal (rather than vicariance) history, without strong evidence of congruence between these species and rivers. However, once a species crossed a river, populations separated by each and every river have remained isolatedâ in this sense, rivers act similarly as barriers to any further gene flow. This result suggests differing degrees of persistence and gives rise to the seeming contradiction that the divergence process indeed varies across time, space and species, even though major Amazonian rivers have acted as secondary barriers to gene flow in the focal taxa.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152608/1/jbi13676_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152608/2/jbi13676.pd
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