Thermally activated exchange narrowing of the Gd3+ ESR fine structure in a single crystal of Ce1-xGdxFe4P12 (x = 0.001) skutterudite

We report electron spin resonance (ESR) measurements in the Gd3+ doped semiconducting filled skutterudite compound Ce1-xGdxFe4P12 (x = 0.001). As the temperature T varies from T = 150 K to T = 165 K, the Gd3+ ESR fine and hyperfine structures coalesce into a broad inhomogeneous single resonance. At T = 200 K the line narrows and as T increases further, the resonance becomes homogeneous with a thermal broadening of 1.1(2) Oe/K. These results suggest that the origin of these features may be associated to a subtle interdependence of thermally activated mechanisms that combine: i) an increase with T of the density of activated conduction-carriers across the T-dependent semiconducting pseudogap; ii) the Gd3+ Korringa relaxation process due to an exchange interaction, J_{fd}S.s, between the Gd3+ localized magnetic moments and the thermally activated conduction-carriers and; iii) a relatively weak confining potential of the rare-earth ions inside the oversized (Fe2P3)4 cage, which allows the rare-earths to become rattler Einstein oscillators above T = 148 K. We argue that the rattling of the Gd3+ ions, via a motional narrowing mechanism, also contributes to the coalescence of the ESR fine and hyperfine structure.Comment: 7 pages, 9 figures, accepted for publication in Phys Rev

Evaluating 5-nitrothiazoles as trypanocidal agents

OA Monitor ExerciseOA Monitor ExerciseThe growth inhibitory properties of a 5-nitrothiazole series was evaluated against Trypanosoma brucei. A subset of related compounds displayed the greatest potency towards the parasite while exhibiting little cytotoxic effect on mammalian cells, with this anti-parasitic activity being dependent on expression of a type I nitroreductase by the trypanosome. We conclude that the 5-nitrothiazole class of nitroheterocycle may represent new leads in the treatment of human African trypanosomiasis.BAV acknowledges financial support by FONDECYT Postdoctorado 313036

Sea Turtles in the Cancer Risk Landscape: A Global Meta-Analysis of Fibropapillomatosis Prevalence and Associated Risk Factors.

Several cancer risk factors (exposure to ultraviolet-B, pollution, toxins and pathogens) have been identified for wildlife, to form a "cancer risk landscape." However, information remains limited on how the spatiotemporal variability of these factors impacts the prevalence of cancer in wildlife. Here, we evaluated the cancer risk landscape at 49 foraging sites of the globally distributed green turtle (Chelonia mydas), a species affected by fibropapillomatosis, by integrating data from a global meta-analysis of 31 publications (1994-2019). Evaluated risk factors included ultraviolet light exposure, eutrophication, toxic phytoplanktonic blooms, sea surface temperature, and the presence of mechanical vectors (parasites and symbiotic species). Prevalence was highest in areas where nutrient concentrations facilitated the emergence of toxic phytoplankton blooms. In contrast, ultraviolet light exposure and the presence of parasitic and/or symbiotic species did not appear to impact disease prevalence. Our results indicate that, to counter outbreaks of fibropapillomatosis, management actions that reduce eutrophication in foraging areas should be implemented

Diversifying the ‘HSI bubble’: Black and Asian women faculty at Hispanic-Serving Institutions

This qualitative case study explored the experiences of seven Black and Asian women faculty at Hispanic-Serving Institutions (HSIs). The unique experience of each woman is shared in this paper. Three themes highlight the interconnectedness of participant experiences. The first theme indicated that these Black and Asian women faculty operated in unsupportive microclimates within their HSIs. Secondly, participants communicated a need for representation within the ‘HSI bubble.’ Finally, our participants felt as though their HSIs needed to exercise greater intentionality in terms of truly serving their student populations. Amongst the implications of this research is a better understanding of the experiences of a minority group (i.e., Black and Asian women faculty) within higher education. These experiences can inform administrators on how to move beyond recruitment of Black and Asian women faculty to foster a supportive microclimate so as to retain these women and enable their success

Clinicopathological And Immunohistochemical Evaluation Of Oral And Oropharyngeal Squamous Cell Carcinoma In Chilean Population

In oral and oropharyngeal squamous cell carcinoma (OCSCC and OPSCC) exist an association between clinical and histopathological parameters with cell proliferation, basal lamina, connective tissue degradation and surrounding stroma markers. We evaluated these associations in Chilean patients. A convenience sample of 37 cases of OCSCC (n=16) and OPSCC (n=21) was analyzed clinically (TNM, clinical stage) and histologically (WHO grade of differentiation, pattern of tumor invasion). We assessed the expression of p53, Ki67, HOXA1, HOXB7, type IV collagen (ColIV) and carcinoma-associated fibroblast (a-SMA-positive cells). Additionally we conducted a univariate/bivariate analysis to assess the relationship of these variables with survival rates. Males were mostly affected (56.2% OCSCC, 76.2% OPSCC). Patients were mainly diagnosed at III/IV clinical stages (68.8% OCSCC, 90.5% OPSCC) with a predominantly infiltrative pattern invasion (62.9% OCSCC, 57.1% OPSCC). Significant association between regional lymph nodes (N) and clinical stage with OCSCC-HOXB7 expression (Chi-Square test P < 0.05) was observed. In OPSCC a statistically significant association exists between p53, Ki67 with gender (Chi-Square test P < 0.05). In OCSCC and OPSCC was statistically significant association between ki67 with HOXA1, HOXB7, and between these last two antigens (Pearson's Correlation test P < 0.05). Furthermore OPSCC-p53 showed significant correlation when it was compared with a-SMA (Kendall's Tau-c test P < 0.05). Only OCSCC-pattern invasion and OPSCC-primary tumor (T) pattern resulted associated with survival at the end of the follow up period (Chi-Square Likelihood Ratio, P < 0.05). Clinical, histological and immunohistochemical features are similar to seen in other countries. Cancer proliferation markers were associated strongly from each other. Our sample highlights prognostic value of T and pattern of invasion, but the conclusions may be limited and should be considered with caution (small sample). 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A metabolomic perspective of the impact of mitochondrial prohibitin on C. elegans longevity.

The mitochondrial prohibitin complex is a context-dependent modulator of longevity. Specifically, prohibitin deficiency shortens the lifespan of otherwise wild type worms, while it dramatically extends lifespan under compromised metabolic conditions, as in the case of the diapause daf-2(e1370) mutant. This extremely intriguingly phenotype has been linked to alterations in mitochondrial function and in fat metabolism. Nevertheless, the true function of the mitochondrial prohibitin complex remains elusive. With the ultimate goal of understanding how mitochondrial prohibitin complex affects longevity, we have employed several metabolomic approaches to characterize the changes elicited upon prohibitin depletion by RNAi on the metabolome of wild type and daf-2 mutant worms.Metabolic analysis by gas chromatography coupled to a flame ionization detector and 1 H-NMR spectroscopy reveals that prohibitin depletion leads to an alteration in the overall fatty acid composition of the worm, as well as in carbohydrate and amino acid metabolism. To enlarge the coverage of the metabolome, we employed a lipidomic mass spectrometry-based approach. We identify that prohibitin has a differential effect in the content of various species of triglycerides and phospholipids in wild type and in daf-2 mutant animals. In particular, we find that prohibitin affects not only the amount but also the composition of fat storage lipids. Overall, prohibitin depletion has a more pronounced effect on the metabolic profiles of wild type worms than of daf-2 mutants indicating that daf-2 mutants are more robust to the changes elicited upon prohibitin depletion. We are currently exploring the relevance of identified metabolites in the context of the effect of prohibitin on the C. elegans longevity.Peer Reviewe