The functional capacity of a battery is observed to decrease, often quite dramatically, as discharge rate demands increase. These capacity losses have been attributed to limited ion access and low ...electrical conductivity, resulting in incomplete electrode use. A strategy to improve electronic conductivity is the design of bimetallic materials that generate a silver matrix in situ during cathode reduction. Ex situ x-ray absorption spectroscopy coupled with in situ energy-dispersive x-ray diffraction measurements on intact lithium/silver vanadium diphosphate (Li/Ag2VP2O8) electrochemical cells demonstrate that the metal center preferentially reduced and its location in the bimetallic cathode are rate-dependent, affecting cell impedance. This work illustrates that spatial imaging as a function of discharge rate can provide needed insights toward improving realizable capacity of bimetallic cathode systems.
Treatment of human epidermal growth factor receptor 2 (HER2)-driven breast cancer with tyrosine kinase inhibitor lapatinib can induce a compensatory HER3 increase, which may attenuate antitumor ...efficacy. Therefore, we explored in vivo HER3 tumor status assessment after lapatinib treatment with zirconium-89 (89Zr)-labeled anti-HER3 antibody mAb3481 positron emission tomography (PET). Lapatinib effects on HER3 cell surface expression and mAb3481 internalization were evaluated in human breast (BT474, SKBR3) and gastric (N87) cancer cell lines using flow cytometry. Next, in vivo effects of daily lapatinib treatment on89Zr-mAb3481 BT474 and N87 xenograft tumor uptake were studied. PET-scans (BT474 only) were made after daily lapatinib treatment for 9 days, starting 3 days prior to 89Zr-mAb3481 administration. Subsequently, ex vivo 89Zr-mAb3481 organ distribution analysis was performed and HER3 tumor levels were measured with Western blot and immunohistochemistry. In vitro, lapatinib increased membranous HER3 in BT474, SKBR3 and N87 cells, and consequently mAb3481 internalization 1.7-fold (BT474), 1.4-fold (SKBR3) and 1.4-fold (N87). 89Zr-mAb3481 BT474 tumor uptake was remarkably high at SUVmean 5.6±0.6 (51.8±7.7%ID/g) using a 10 μg 89Zr-mAb3481 protein dose in vehicle-treated mice. However, compared to vehicle, lapatinib did not affect 89Zr-mAb3481 ex vivo uptake in BT474 and N87 tumors, while HER3 tumor expression remained unchanged. In conclusion, lapatinib increased in vitro HER3 tumor cell expression, but not when these cells were xenografted. 89Zr-mAb3481 PET accurately reflected HER3 tumor status. 89Zr-mAb3481 PET showed high, HER3-specific tumor uptake, and such an approach might sensitively assess HER3 tumor heterogeneity and treatment response in patients.
Mass-independent fractionation of sulfur isotopes (reported as Δ33S) recorded in Archean sedimentary rocks helps to constrain the composition of Earth’s early atmosphere and the timing of the rise of ...oxygen ~2.4 billion years ago. Although current hypotheses predict uniformly negative Δ33S for Archean seawater sulfate, this remains untested through the vast majority of Archean time. We applied x-ray absorption spectroscopy to investigate the low sulfate content of particularly well-preserved Neoarchean carbonates and mass spectrometry to measure their Δ33S signatures. We report unexpected, large, widespread positive Δ33S values from stratigraphic sections capturing over 70 million years and diverse depositional environments. Combined with the pyrite record, these results show that sulfate does not carry the expected negative Δ33S from sulfur mass-independent fractionation in the Neoarchean atmosphere.
Los sitios con entierros humanos y evidencias de actividades residenciales, situados en sectores sobreelevados del paisaje, son un rasgo característico del patrón de ocupación prehispánica de la ...Cuenca del Río Negro. El estudio de algunos de estos sitios y, sobre todo, de los restos humanos en ellos recuperados, ha sido empleado por numerosos investigadores para explorar las diversas formas en las cuales los cazadores-recolectores se relacionaron con la muerte y discutir problemas de carácter social tales como prácticas rituales y religiosas, patrones de movilidad y procesos vinculados con la complejidad social. Aportamos aquí información cronológica y contextual de varios sitios en donde coinciden espacialmente los productos materiales de actividades domésticas y prácticas mortuorias, y discutimos las posibles relaciones entre ambos tipos de registro. Sobre la base de la información preexistente y de nuevos datos, retomamos el problema relativo a la interpretación y conceptualización de estos sitios y discutimos las nociones de cementerio y área formal de entierro. Finalmente, proponemos que estos sitios, ocupados de manera recurrente durante el Holoceno Tardío, pueden definirse como lugares persistentes (sensu Schlanger 1992) y que su configuración actual es el resultado de una compleja confluencia de condicionantes de índole religiosa, social y ambiental.
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