By 2009, reverberations of economic crisis spread from the United States around the globe. As corporations across the United States folded, however, small businesses on the Qualla Boundary of the ...Eastern Band of Cherokee Indians (EBCI) continued to thrive. In this rich ethnographic study, Courtney Lewis reveals the critical roles small businesses such as these play for Indigenous nations. The EBCI has an especially long history of incorporated, citizen-owned businesses located on their lands. When many people think of Indigenous-owned businesses, they stop with prominent casino gaming operations or natural-resource intensive enterprises. But on the Qualla Boundary today, Indigenous entrepreneurship and economic independence extends to art galleries, restaurants, a bookstore, a funeral parlor, and more.Lewis's fieldwork followed these businesses through the Great Recession and against the backdrop of a rapidly expanding EBCI-owned casino. Lewis's keen observations reveal how Eastern Band small business owners have contributed to an economic sovereignty that empowers and sustains their nation both culturally and politically.
The synthesis of MXenes is a lively area of research in today’s materials science community. Pure carbide and nitride samples with tunable properties and crystal size are desirable for the ...implementation of these promising young materials in the wider economy. Herein, the preparation of Ti3AlC2 MAX phase has been studied with a view to improving the quality and purity of the resultant Ti3C2 MXene. Room-temperature high-energy ball milling is exploited for the mechanical activation of elemental powder mixtures, which, along with adjusted input stoichiometry and heat treatment, achieves high-purity and highly crystalline Ti3AlC2 and Ti3C2 with rather quick and easy methodology. Several approaches are offered, as not all of these preparation steps are strictly necessary for acquiring MXene. The structure and properties of Ti3C2 are shown to depend on the preparation history and precursor characteristics. The MXene is additionally shown to perform well as a substrate for binder-free electrochemical cell electrodes; high electrical conductivity and cycling stability render this MXene@Zn anode a viable option for aqueous Zn-ion systems.
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•Careful adjustment of input stoichiometry (3.4Ti + 1.5Al + 2C) allows for minimisation of MAX phase and MXene impurities.•Ball milling of Ti-Al-C powders for 4h 40min at 700rpm is shown to produce pure Ti3AlC2, suitable for Ti3C2 synthesis.•Mechanical activation of elemental powder mixture tunes final Ti3C2 MXene lateral size from 3 μm (non-activated) to 1.5 μm (activated).•As an anode for Zn-ion electrochemical systems, Ti3C2 plated with 4 mAh/cm2 of Zn is stable for >100 cycles with overpotential ~200 mV.
Single position lateral fusion with robotic assistance eliminates the need for surgical staging while harnessing the precision of robotic adjuncts. We expand on this technique by demonstrating the ...technical feasibility of placing bilateral pedicle screws with S2-alar-iliac (S2AI) fixation while in the lateral position.
A cadaveric study was performed using 12 human specimens. A retrospective clinical series was also performed for patients who had undergone robot-assisted placement of S2AI screws in lateral decubitus between June 2020 and June 2022. Case demographics, implant placement time, implant size, screw accuracy, and complications were recorded. Early postoperative radiographic outcomes were reported.
In the cadaveric series, a total of 126 screws were placed with robotic assistance in 12 cadavers of which 24 screws were S2AI. There were four breaches from pedicle screws and none with S2AI screws for an overall accuracy rate of 96.8%. In the clinical series, four patients (all male, mean age 65.8 years) underwent single position lateral surgery with S2AI distal fixation. Mean BMI was 33.6 and mean follow-up was 20.5 months. Mean radiographic improvements were lumbar lordosis 12.3 ± 4.7°, sagittal vertical axis 1.5 ± 2.1 cm, pelvic tilt 8.5 ± 10.0°, and pelvic incidence-lumbar lordosis mismatch 12.3 ± 4.7°. A total of 42 screws were placed of which eight screws were S2AI. There were two breaches from pedicle screws and none from S2AI screws for an overall accuracy rate of 95.2%. No repositioning or salvage techniques were required for the S2AI screws.
We demonstrate here the technical feasibility of single position robot-assisted placement of S2-alar-iliac screws in the lateral decubitus position for single position surgery.
Wearing face masks (alongside physical distancing) provides some protection against infection from COVID-19. Face masks can also change how people communicate and subsequently affect speech signal ...quality. This study investigated how three common face mask types (N95, surgical, and cloth) affected acoustic analysis of speech and perceived intelligibility in healthy subjects. Acoustic measures of timing, frequency, perturbation, and power spectral density were measured. Speech intelligibility and word and sentence accuracy were also examined using the Assessment of Intelligibility of Dysarthric Speech. Mask type impacted the power distribution in frequencies above 3 kHz for the N95 mask, and above 5 kHz in surgical and cloth masks. Measures of timing and spectral tilt mainly differed with N95 mask use. Cepstral and harmonics to noise ratios remained unchanged across mask type. No differences were observed across conditions for word or sentence intelligibility measures; however, accuracy of word and sentence translations were affected by all masks. Data presented in this study show that face masks change the speech signal, but some specific acoustic features remain largely unaffected (e.g., measures of voice quality) irrespective of mask type. Outcomes have bearing on how future speech studies are run when personal protective equipment is worn.
Cytochrome P450s (CYP450s) are a versatile superfamily of enzymes known to undergo rapid evolution. They have important roles across growth and development pathways in crustaceans, although it is ...difficult to characterise orthologs between species due to their sequence diversity. Conserved CYP450s enzymes in crustaceans are those associated with ecdysteroidogenesis: synthesising and breaking down the active moult hormone, 20-hydroxyecdysone. The complex life cycle of the ornate spiny lobster,
, relies on moulting in order to grow and develop. Many of these diverse life stages have been analysed to establish a comprehensive transcriptomic database for this species. The transcripts putatively encoding for CYP450s were mapped using transcriptomic analysis and identified across growth and development stages. With the aid of phylogeny, 28 transcripts of 42 putative
CYP450s were annotated, including the well conserved Halloween genes, which are involved in ecdysteroidogenesis. Expression patterns across the life stages determined that only a subset of the CYP450s can be detected in each life stage or tissue. Four
transcripts show overlapping expression between metamorphosis and adult tissues, suggesting pleotropic functions of the multiple
orthologs within
.
The optoelectronic signatures of free-standing few-atomic-layer black phosphorus nanoflakes are analyzed by in situ transmission electron microscopy (TEM). As compared to other 2D materials, the band ...gap of black phosphorus (BP) is related directly to multiple thicknesses and can be tuned by nanoflake thickness and strain. The photocurrent measurements with the TEM show a stable response to infrared light illumination and change of nanoflakes band gap with deformation while pressing them between two electrodes assembled in the microscope. The photocurrent spectra of an 8- and a 6-layer BP nanoflake samples are comparatively measured. Density functional theory (DFT) calculations are performed to identify the band structure changes of BP during deformations. The results should help to find the best pathways for BP smart band gap engineering via tuning the number of material atomic layers and programmed deformations to promote future optoelectronic applications.
Vanadium carbide MXenes have demonstrated both one of the highest theoretical capacities for Li and Mg storage among all members of the MXene family and a high performance as cathodes for ...high-energy-density Zn-ion batteries (ZIBs). However, V2C research has been limited because of the instability of delaminated V2C (d-V2C) in water suspension. Herein, we propose improvements of the HF-free synthesis of V2C MXenes via selective etching of the V2AlC MAX phase by a HCl and LiF mixture. A combination of etching in the closed environment of the hydrothermal autoclave under continuous stirring and thermal isolation of a reaction vessel and improved washing techniques result in high-quality d-V2C MXene nanostructures. High crystallinity and chemical purity of the as-synthesized materials is confirmed by X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and aberration-corrected high-resolution transmission electron microscopy. A high concentration of Li cations in the etching mixture results in significantly improved stability of d-V2C in water suspension. In addition, cyclic voltammetry analysis is conducted to gauge the electrochemical characteristics of fabricated d-V2C MXenes. Electrochemical tests confirm that fabricated MXenes are highly promising as cathode materials for aqueous ZIBs. Moreover, a charge storage mechanism of V2C MXenes can be tuned through the implementation of different synthetic methods as well as electrochemical activation protocols.
•A series of novel Mg-substituted triclinic Na2Mn3-xMgxO7 cathode materials was introduced.•Mg-substitution improved specific capacity and rate capability of the cathodes.•Ex situ methods (X-ray ...diffraction and X-ray absorption spectroscopy) demonstrated that the capacity evolved through reversible Mn3+/4+ and O2-/n- redox reactions.•Capacity evolution was assisted through a reversible triclinic to monoclinic structural transition.•Full cell performance was analyzed.
Triclinic Na2Mn3O7 has been identified as a promising material for high-capacity sodium-ion batteries. However, the knowledge on the effect of doping of metal ions and structural transformations of Na2Mn3O7 during dis(charge) is limited. Integration of alkali metal-ions, specially Mg2+ can enhance the electrochemical properties in transition metal oxides. Herein, a series of Mg2+ doped triclinic Na2Mn3O7 cathode materials was explored for the first time. Electrochemical analysis revealed that Mg2+ improves specific capacities, and rate capabilities. Ex situ X-ray diffraction (XRD) and Galvanostatic charge discharge cycling (GCD) showed that the triclinic phase reversibly converts into two monoclinic phases at high Na+ insertion levels. Na+ extraction at high potentials is supported by another biphasic region which converts to a major triclinic phase at the end of the charge. GCD, cyclic voltammetry (CV) and ex situ X-ray absorption spectroscopy (XAS) documented that the capacity mainly evolved through a Mn4+/3+ redox couple and a reversible O2-/n− redox reaction. CV and Galvanostatic intermittent titration techniques (GITT) showed that Mg2+ reduces the Na+-vacancy ordering and improves the Na+ diffusion. The 2 mol.% Mg-doped material exhibited a high specific capacity of 143 mAh/g after 30 cycles and a rate capability of 93 mAh/g (at 500 mA/g). GCD analysis demonstrated that O2-/n− redox is remarkably stable up to at least 90 cycles. Full cells made using the 0.5 mol.% Mg-doped material displayed a promising discharge specific capacity of 80 mAh/g. The effects of cation doping into the complex crystal structures, phase transformations during Na+ de(intercalation) and the importance of O2-/n− redox for achieving high capacities were uncovered. The findings of this work will guide the design of novel cathode materials for sodium-ion batteries.
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