ABSTRACT
Aqueous redox flow battery systems that use a zinc negative electrode have a relatively high energy density. However, high current densities can lead to zinc dendrite growth and electrode polarization, which limit the battery's high power density and cyclability. In this study, a perforated copper foil with a high electrical conductivity was used on the negative side, combined with an electrocatalyst on the positive electrode in a zinc iodide flow battery. A significant improvement in the energy efficiency (ca. 10% vs using graphite felt on both sides) and cycling stability at a high current density of 40 mA cm-2 was observed. A long cycling stability with a high areal capacity of 222 mA h cm-2 is obtained in this study, which is the highest reported areal capacity for zinc-iodide aqueous flow batteries operating at high current density, in comparison to previous studies. Additionally, the use of a perforated copper foil anode in combination with a novel flow mode was discovered to achieve consistent cycling at exceedingly high current densities of >100 mA cm-2. In situ and ex situ characterization techniques, including in situ atomic force microscopy coupled with in situ optical microscopy and X-ray diffraction, are applied to clarify the relationship between zinc deposition morphology on the perforated copper foil and battery performance in two different flow field conditions. With a portion of the flow going through the perforations, a significantly more uniform and compact zinc deposition was observed compared to the case where all of the flow passed over the surface of the electrode. Results from modeling and simulation support the conclusion that the flow of a fraction of electrolyte through the electrode enhances mass transport, enabling a more compact deposit.
ABSTRACT
Objectives: The aim of this systematic review was to assess the scientific evidence on the effect of rotary versus manual instrumentation for root canal preparation in primary teeth. Materials and Methods: Search terms were selected based on Medical Subject Headings (MeSH) and non-MeSH terms. Electronic database search of English published literature was performed in March 2020 within the following databases: Scopus, Cochrane, PubMed, and Embase. The risk of bias of selected studies was assessed by means of Cochrane collaboration tool. The heterogeneity level among the included studies was measured by I 2 index. For statistical analysis of instrumentation time, standard mean difference (SMD) of continuous data was analyzed with 95% confidence intervals (95% CIs) using the fixed-effects model. A random-effects model was used for analysis of odds ratio (OR) to assess the probability of optimal fill, underfill, and overfill obturations. Forest plots were applied to show the results and to estimate the effectiveness of rotary instrumentation. Results: Seven articles were selected for this review. The SMD in rotary techniques was 1.79 min less than manual techniques (95% CI: -2.56--1.03 min) and had a significant P = 0.001. The OR of optimum quality was calculated to be 3.53 (95% CI: 1.79-6.97) in the rotary technique at P = 0.254. Conclusions: Within the limitations of this review, it can be asserted that rotary files decrease the instrumentation time and increase the rates of optimally filled canals in primary teeth. However, these files do not decrease the risk of underfilling and overfilling compared to manual files.
ABSTRACT
The diversity of the U.S. population is currently not reflected in the genomic workforce and across the greater scientific enterprise. Although diversity and inclusion efforts have focused on increasing the number of individuals from underrepresented groups across scientific fields, structural racism remains. Thus, the cultivation and adoption of diversity as an ethos requires shifting our focus to being intentional about an institution's character, culture, and climate. One way for this ethos to be sustained is by facilitating an intentional anti-racism approach within the field. Adopting a new perspective on diversity utilizing an anti-racism approach will support genomics researchers as we build supportive, collaborative research environments. We seek to expand critical thought in the framing of diversity in the research enterprise and propose an anti-racism approach that informs deliberate actions required to address structural racism.
