Search

Mixed anion compounds afford considerable compositional diversity and tunability of function. A challenging aspect of anion control of properties of periodic solids is to preserve the crystal lattice while substituting for different anions of widely varying size and hardness. Post-synthetic modification routes that place cations or anions in non-equilibrium configurations represent a promising means of decoupling composition and crystal structure and for accessing metastable solids; however, such methods remain relatively unexplored for anion placement. Here, we report the synthesis of LaOI nanocrystals by a non-hydrolytic sol-gel condensation reaction and their transformation into LaOBr, LaOCl, and LaOF nanocrystals along hard-soft-acid-base principles using post-synthetic metathesis reactions with ammonium halides. Anion displacement proceeds along halide planes preserving the tetragonal matlockite structure. Energy-variant X-ray excited optical luminesce signatures of alloyed Tb3+-ions serves as a sensitive quantum reporter of the preservation of the cation sublattice and hardening of the crystal structure upon anion replacement.

Summary Intercalation-induced phase transformations in Li-ion battery electrode materials give rise to multi-phase coexistence regimes within individual particles, generating significant lattice coherency strain across dynamically evolving interfaces. We demonstrate here that the lattice coherency strain can be alleviated by leveraging the coupling of electrochemistry, mechanics, and particle geometry to achieve controllable nucleation and deterministic ion transport. Here, we contrast singular kinks and continuous curvature as a means of enabling homogeneous lithiation without developing large stresses within a model cathode material, V2O5. The singular kink confirms that local curvature facilitates lithiation but also exacerbates lithiation inhomogeneities and elastic misfit strain. In contrast, the incorporation of continuous curvature enables homogeneous single-phase lithiation, mitigating lattice coherency strain. The studies provide a direct view of the coupling of mechanics and electrochemistry within crystalline electrodes and suggest that mesoscale architectures can help resolve key failure mechanisms limiting the performance of energy-storage systems without sacrificing charge/discharge kinetics.

Rare-earth scheelites represent a diverse family of compounds with multiple degrees of freedom, which enables the incorporation of a wide range of lanthanide color centers. Precise positioning of quantum objects is attainable by the choice of alkali cations and lattice connectivity of polyanion units. Herein, we report the structure-dependent energy transfer and lattice coupling of optical transitions in La3+- and Dy3+-containing scheelite-type double and quadruple molybdates NaLa1-xDyx(MoO4)2 and Na5La1-xDyx(MoO4)4. X-ray excitation of La3+ core states generates excited-state electron-hole pairs, which, upon thermalizing across interconnected REO8 polyhedra in double molybdates, activate a phonon-coupled excited state of Dy3+. A pronounced luminescence band is observed corresponding to optical cooling of the lattice upon preferential radiative relaxation from a "hot" state. In contrast, combined X-ray absorption near-edge structure and X-ray-excited optical luminescence studies reveal that such a lattice coupling mechanism is inaccessible in quadruple molybdates with a greater separation of La3+-Dy3+ centers.

The utilization of metallic anodes holds promise for unlocking high gravimetric and volumetric energy densities and is pivotal to the adoption of ‘beyond Li’ battery chemistries. Much of the promise of magnesium batteries stems from claims regarding their lower predilection for dendrite growth. Whilst considerable effort has been invested in the design of novel electrolytes and cathodes, detailed studies of Mg plating are scarce. Using galvanostatic electrodeposition of metallic Mg from Grignard reagents in symmetric Mg–Mg cells, we establish a phase map characterized by disparate morphologies spanning the range from fractal aggregates of 2D nanoplatelets to highly anisotropic dendrites with singular growth fronts and nanowires entangled in the form of mats. The effects of electrolyte concentration, applied current density, and coordinating ligands have been explored. The study demonstrates a complex range of electrodeposited morphologies including canonical dendrites with shear moduli conducive to penetration through typical polymeric separators. We further demonstrate a strategy for mitigating Mg dendrite formation based on the addition of molecular Lewis bases that promote nanowire growth through selective surface coordination.

Increased adoption of engineered aluminum alloys in vehicular components is imperative for automotive lightweighting, but such alloys are oftentimes prone to degradation upon exposure to corrosive ...

Negative-emissions technologies to capture atmospheric greenhouse gases are urgently needed to achieve ambitious global emissions targets and limit the catastrophic long-term effects of climate change. This Voices asks: do you feel there are any misconceptions or myths surrounding the goal of achieving negative emissions and how it is discussed in the literature? For this field to move forward, how should negative emissions be conceptualized across disciplines?

Data-driven approaches have brought about a revolution in manufacturing; however, challenges persist in their applications to synthetic strategies. Their application to the deterministic navigation of reaction trajectories to stabilize crystalline solids with precise composition, atomic connectivity, microstructural dimensionality, and surface structure remains a frontier in inorganic materials research. The design of synthetic methodologies for the preparation of inorganic materials is often inefficient in terms of exploration of potentially vast design spaces spanning multiple process variables, reaction sequences, as well as structural parameters and reactivities of precursors and structure-directing agents. Reported synthetic methods are further limited in terms of the insight they provide into underlying chemical and physical principles. The recent surge in interest in accelerating the discovery of new materials can be considered as an opportunity to re-evaluate our approach to materials synthesis, and for considering new frameworks for exploration that are systematic and strategic in approach. Herein, we outline with the help of several illustrative examples, the challenges, opportunities, and limitations of data-driven synthesis design. The account collates discussion of design-of-experiments sampling methods, machine learning modeling, and active learning to develop experimental workflows that accelerate the experimental navigation of synthetic landscapes.

Public health advocates often encounter the arduous rhetorical situation of championing issues assumed to be personal. One such rhetorical situation can be observed in pro-caregiving advocacy rhetoric; organizations promoting public policy attention for unpaid family caregivers. This essay argues that pro-caregiving advocates invite public action by persuasively advancing personal and public problems that impact caregivers, care-receivers, taxpayers, and businesses; however, in their policy statements, advocates undo the likelihood of public action by creating a partial solution that emphasizes the preferred location of home care and de-emphasizes the ways in which the financial and health-related caregiver problems get solved. The essay concludes with rhetorical lessons that highlight the practical applicability of argumentation methodology for scholars and practitioners of public health advocacy. In doing so, this essay offers practical tools to evaluate and reposition the efforts of health advocates moving an issue from personal to public.

The conversion and numerical amplification of X-ray photons to visible light is at the heart of numerous technological applications spanning the range from X-ray detectors and scintillators to radiographic medical imaging devices. The need for increased sensitivity and spatial resolution to reduce radiation exposure and provide better differentiation of specimens presenting an X-ray contrast has been a strong driving force in the search for novel X-ray phosphors. However, the current palette of X-ray phosphors is rather sparse. The development of color tunable phosphors necessitates the incorporation of multiple dopants, which in turn interact through complex sensitization mechanisms that are poorly understood for high-energy excitation. In this work, we describe the stabilization of multiply alloyed LaOCl nanocrystals incorporating Tb3+ cations in conjunction with either divalent or trivalent europium ions, yielding phosphors emitting in the blue–green and green–red regions of the electromagnetic spectru...

Dr. Spock’s, The Common Sense Book of Baby and Child Care, one of the best-selling self-help texts of all-time, “second only to the Bible in popularity” (Meakin & Tattersall, 2004) was one of the most influential childcare books in American culture. The author has been both heralded and disparaged as instrumental in the shaping of untold generations. In the present study, we address the rhetorical construction of the Spockian Mother as she is developed during Spock’s tenure from 1946–1992. We employ a feminist rhetorical perspective to examine the progression of Spock’s texts in order to understand how patriarchal images of motherhood are constructed and maintained through Spock’s lifetime and the first 46 years of its publication. We argue that Spock both reinforced and challenged the institution of motherhood; he challenged institutionalized motherhood by encouraging mothers to “trust themselves” while simultaneously conforming to a patriarchal model of motherhood which is at odds with empowered mothering.

Corrosion inhibition offered by unfunctionalized exfoliated graphite polymer composite coatings for protection of aluminum alloy 7075 substrates is described.

We demonstrate the growth of dendritic magnesium deposits with fractal morphologies exhibiting shear moduli in excess of values for polymeric separators upon the galvanostatic electrodeposition of metallic Mg from Grignard reagents in symmetric Mg–Mg cells. Dendritic growth is understood on the basis of the competing influences of reaction rate, electrolyte transport rate, and self-diffusion barrier.

This essay analyzes a controversy involving Amelia (Mia) Rivera, a three-year old girl who was denied a life-saving kidney transplant in January 2012. As reported by Mia's mother, Chrissy, on her blog post, Mia was denied the kidney transplant because of her mental disability. Throughout the public discussion that took place over a few short weeks, we argue Mia's ineligibility was rearticulated through rhetorics of motherhood, unjust body language, and questions about medical authority. we suggest this indicates that descriptions of the body and its able-ness carry more weight in the public's understanding of health issues than does medical authority.