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Here, we demonstrate a two-step electrosynthesis approach for the preparation of silver pyrovanadate, Ag 4 V 2 O 7 in thin-film form. In the first, cathodic step, polycrystalline Ag was deposited on fluorine doped tin oxide (FTO) substrate from a non-aqueous bath. Aqueous pyrovanadate species were then generated by aging of a CO 2 -infused sodium orthovanadate (Na 3 VO 4 ) solution for three weeks. Silver ions were subsequently generated in situ in this medium using anodic stripping of the Ag/ITO films from the first step. Interfacial precipitation of the Ag + ions with the pyrovanadate species afforded the targeted product in phase pure form. The various stages of the electrosynthesis were monitored in situ via the combined use of voltammetry, electrochemical quartz crystal nanogravimetry (EQCN), and coulometry. The Ag 4 V 2 O 7 thin films were characterized by a variety of experimental techniques, including X-ray diffraction, laser Raman spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. Surface photovoltage spectroscopy, ambient-pressure photoemission spectroscopy, and Kelvin probe contact potential difference (work function) measurements afforded information on the energy band structure of the p -type Ag 4 V 2 O 7 semiconductor. Finally, the electrochemical and photoelectrochemical properties of the electrosynthesized Ag 4 V 2 O 7 thin films were studied in both aqueous and non-aqueous electrolytes. 

The cyanobacterial clock presents a unique opportunity to understand the biochemical basis of circadian rhythms. The core oscillator, composed of the KaiA, KaiB, and KaiC proteins, has been extensively studied, but a complete picture of its connection to the physiology of the cell is lacking. To identify previously unknown components of the clock, we used KaiB locked in its active fold as bait in an immunoprecipitation/mass spectrometry approach. We found that the most abundant interactor, other than KaiC, was a putative diguanylate cyclase protein predicted to contain multiple Per-Arnt-Sim (PAS) domains, which we propose to name KidA. Here we show that KidA directly binds to the fold-switched active form of KaiB through its N-terminal PAS domains. We found that KidA shortens the period of the circadian clock both in vivo and in vitro and alters the ability of the clock to entrain to light-dark cycles. The dose-dependent effect of KidA on the clock period could be quantitatively recapitulated by a mathematical model in which KidA stabilizes the fold-switched form of KaiB, favoring rebinding to KaiC. Put together, our results show that the period and amplitude of the clock can be modulated by regulating the access of KaiB to the fold-switched form. 

This study presents a video-based case study of families who used discussion prompts in the at-home engineering kits. We examine different roles that caregivers took on during the implementation of the prompts to organize families’ engineering learning activities. Narrative accounts and transcriptions were analyzed to investigate the different roles that caregivers took. Three roles emerged: caregivers as monitor; caregivers as mentor; caregivers as partner. We further coded families’ talks to investigate how three different caregivers’ roles influenced families’ engineering practices and caregiver-child talk types. Preliminary findings illustrate how three caregivers’ roles enabled and constrained different types of engineering practices and caregiver-child talk types. Findings contribute to future considerations in designing discussion prompts for at-home engineering kits. 

RNA degradation is fundamental for cellular homeostasis. The process is carried out by various classes of endolytic and exolytic enzymes that together degrade an RNA polymer to mono-ribonucleotides. Within the exoribonucleases, nano-RNases play a unique role as they act on the smallest breakdown products and hence catalyze the final steps in the process. We recently showed that oligoribonuclease (Orn) acts as a dedicated diribonuclease, defining the ultimate step in RNA degradation that is crucial for cellular fitness (Kim et al., 2019). Whether such a specific activity exists in organisms that lack Orn-type exoribonucleases remained unclear. Through quantitative structure-function analyses, we show here that NrnC-type RNases share this narrow substrate length preference with Orn. Although NrnC and Orn employ similar structural features that distinguish these two classes of dinucleases from other exonucleases, the key determinants for dinuclease activity are realized through distinct structural scaffolds. The structures, together with comparative genomic analyses of the phylogeny of DEDD-type exoribonucleases, indicate convergent evolution as the mechanism of how dinuclease activity emerged repeatedly in various organisms. The evolutionary pressure to maintain dinuclease activity further underlines the important role these analogous proteins play for cell growth. 

The objective of this three-year National Science Foundation’s Innovative Technology Experiences for Students and Teachers (NSF-ITEST) project is to develop, implement, and refine a program for integrating engineering design practices with an emphasis on emerging technologies (i.e., making, DIY electronics) into home environments of families with a child in grade 3-6 from under-resourced communities. This project has two components. Each family (1) defines a home- or community-based problem and creates a prototype to improve the lives of self or others; and (2) engages in low-cost engineering design kits in their home environments. This paper presents findings from two years of interview data, as well video data collected in project sessions and home environments from 21 families. Results are presented as highlights of finding from on-going analyses to address three research aims.