Impact of Structural Changes on Energy Transfer in the Anion-Engineered Re3+:Y2O3 Through Low-Temperature Synthesis Approach.

Anion engineering has proven to be an effective strategy to tailor the physical and chemical properties of metal oxides by modifying their existing crystal structures. In this work, a low-temperature synthesis for rare earth (RE)-doped Y2O2SO4 and Y2O2S was developed via annealing of Y(OH)3 intermediates in the presence of elemental sulfur in a sealed tube, followed by a controlled reduction step. The crystal structure patterns (X-ray diffraction) and optical spectra (UV-IR) of Y2O2SO4, Y2O2S, and crystalline Y2O3 were collected throughout the treatment steps to correlate the structural transformations (via thermogravimetric analysis) with the optical properties. Local and long-range crystallinities were characterized by using X-ray and optical spectroscopy approaches. Systematic shifts in the Eu3+ excitation and emission peaks were observed as a function of SO42- and S2- concentrations resulting from a crystal evolution from cubic (Y2O3) to trigonal (Y2O2S) and monoclinic (Y2O2SO4), which can modify the local hybridization of sensitizer dopants (i.e., Ce3+). Ultimately, Tb3+ and Tb3+/Ce3+ doping was employed in these hosts (Y2O2SO4, Y2O2S, and Y2O3) to understand energy transfer between sensitizer and activator ions, which showed significant enhancement for the monoclinic sulfate structure.

Zeolite Supported Pt for Depolymerization of Polyethylene by Induction Heating.

We demonstrate that for polyethylene depolymerization with induction heating (IH), using a bifunctional (Pt- or Pt-Sn-containing zeolite) hydrocracking catalyst, we can obtain high hydrocarbon product yields (up to 95 wt % in 2 h) at a relatively low surface temperature (375 °C) and with a tunable product distribution ranging from light gas products to gasoline- to diesel-range hydrocarbons. Four zeolite types [MFI, LTL, CHA(SSZ-13), and TON] were chosen as the supports due to their varying pore sizes and structures. These depolymerization results are obtained at atmospheric pressure and without the use of H2 and result in an alkane/alkene mixture with virtually no methane, aromatics, or coke formation. We also demonstrate how IH helps overcome diffusional resistances associated with conventional thermal heating and thereby shortens reaction times.

Solving inherited white matter disorder etiologies in the neurology clinic: Challenges and lessons learned using next-generation sequencing.

Introduction: Rare neurodevelopmental disorders, including inherited white matter disorders or leukodystrophies, often present a diagnostic challenge on a genetic level given the large number of causal genes associated with a range of disease subtypes. This study aims to demonstrate the challenges and lessons learned in the genetic investigations of leukodystrophies through presentation of a series of cases solved using exome or genome sequencing. Methods: Each of the six patients had a leukodystrophy associated with hypomyelination or delayed myelination on MRI, and inconclusive clinical diagnostic genetic testing results. We performed next generation sequencing (case-based exome or genome sequencing) to further investigate the genetic cause of disease. Results: Following different lines of investigation, molecular diagnoses were obtained for each case, with patients harboring pathogenic variants in a range of genes including TMEM106B, GJA1, AGA, POLR3A, and TUBB4A. We describe the lessons learned in reaching the genetic diagnosis, including the importance of (a) utilizing proper multi-gene panels in clinical testing, (b) assessing the reliability of biochemical assays in supporting diagnoses, and (c) understanding the limitations of exome sequencing methods in regard to CNV detection and region coverage in GC-rich areas. Discussion: This study illustrates the importance of applying a collaborative diagnostic approach by combining detailed phenotyping data and metabolic results from the clinical environment with advanced next generation sequencing analysis techniques from the research environment to increase the diagnostic yield in patients with genetically unresolved leukodystrophies.

Impact of Sc3+-Modified Local Site Symmetries on Er3+ Ion Upconversion Luminescence in Y2O3 Nanoparticles.

Rare earth (RE) doped yttria sesquioxide has been widely used as host materials for upconversion (UC) phosphors due to their high refractive index, wide band gap, and high melting point. Meanwhile, while fluoride matrices with low phonon cutoff energies exhibit stronger UC emissions, RE-doped oxides exhibit better thermal stability and higher thermal sensitivity when applied as optical temperature sensors. In this work, Sc3+ is substituted in RE-doped Y2O3 lattices to generate smaller cation sites, enhancing the crystal field and modifying the allowed optical transitions. Er3+ is used as a photoluminescent probe to study the effect of site position and symmetry on the UC performance. In comparison with the traditional hydrothermal method, Sc3+ is successfully incorporated into the Y2O3 lattice via the co-precipitation/molten salt method without segregating observed. The Judd-Ofelt analysis was applied to determine the local symmetry and efficiency changes. Sc was found to be able to improve the luminescence performances of Er in Y2-x Sc x O3 (YScO) hosts by adjusting the local symmetry level around the luminescent sites. The local symmetry level was reduced with less than 30 mol % of Sc doping concentration based on the changes in Ω2 values. Meanwhile, the YScO oxide was found to significantly improve the luminescence intensity and red-to-green ratio at a lower Yb3+ concentration (5 mol %) instead of a higher concentration (20 mol %) commonly used. This was attributed to an increased energy transfer between the closer Yb3+-Er3+ pairs. Overall, this work allows the spatial occupancy of luminescence centers in the metal oxide host materials to optimize the UC luminescence performance and develop a high-efficiency oxide material for high-temperature applications such as optical thermometry.

Generation of 3D Spheroids Using a Thiol-Acrylate Hydrogel Scaffold to Study Endocrine Response in ER+ Breast Cancer.

Culturing cancer cells in a three-dimensional (3D) environment better recapitulates in vivo conditions by mimicking cell-to-cell interactions and mass transfer limitations of metabolites, oxygen, and drugs. Recent drug studies have suggested that a high rate of preclinical and clinical failures results from mass transfer limitations associated with drug entry into solid tumors that 2D model systems cannot predict. Droplet microfluidic devices offer a promising alternative to grow 3D spheroids from a small number of cells to reduce intratumor heterogeneity, which is lacking in other approaches. Spheroids were generated by encapsulating cells in novel thiol-acrylate (TA) hydrogel scaffold droplets followed by on-chip isolation of single droplets in a 990- or 450-member trapping array. The TA hydrogel rapidly (∼35 min) polymerized on-chip to provide an initial scaffold to support spheroid development followed by a time-dependent degradation. Two trapping arrays were fabricated with 150 or 300 µm diameter traps to investigate the effect of droplet size and cell seeding density on spheroid formation and growth. Both trapping arrays were capable of ∼99% droplet trapping efficiency with ∼90% and 55% cellular encapsulation in trapping arrays containing 300 and 150 µm traps, respectively. The oil phase was replaced with media ∼1 h after droplet trapping to initiate long-term spheroid culturing. The growth and viability of MCF-7 3D spheroids were confirmed for 7 days under continuous media flow using a customized gravity-driven system to eliminate the need for syringe pumps. It was found that a minimum of 10 or more encapsulated cells are needed to generate a growing spheroid while fewer than 10 parent cells produced stagnant 3D spheroids. As a proof of concept, a drug susceptibility study was performed treating the spheroids with fulvestrant followed by interrogating the spheroids for proliferation in the presence of estrogen. Following fulvestrant exposure, the spheroids showed significantly less proliferation in the presence of estrogen, confirming drug efficacy.

Use of Neuromuscular Ultrasound in the Diagnosis of Disulfiram Polyneuropathy.

ABSTRACT: We present the case of a 37-year-old woman with alcohol use disorder, who developed leg cramping, bilateral foot drop, and hand weakness 3 months after starting disulfiram. This was accompanied by an 18-pound involuntary weight loss. Electrophysiologic findings showed a motor predominant axonal neuropathy. Neuromuscular ultrasound showed normal to small cross-sectional area of all nerves studied. This case is discussed, and the ultrasound findings are compared with another reported case.

Induction Heating of Magnetically Susceptible Nanoparticles for Enhanced Hydrogenation of Oleic Acid.

Radio frequency (RF) induction heating was compared to conventional thermal heating for the hydrogenation of oleic acid to stearic acid. The RF reaction demonstrated decreased coke accumulation and increased product selectivity at comparable temperatures over mesoporous Fe3O4 catalysts composed of 28-32 nm diameter nanoparticles. The Fe3O4 supports were decorated with Pd and Pt active sites and served as the local heat generators when subjected to an alternating magnetic field. For hydrogenation over Pd/Fe3O4, both heating methods gave similar liquid product selectivities, but thermogravimetric analysis-differential scanning calorimetry measurements showed no coke accumulation for the RF-heated catalyst versus 6.5 wt % for the conventionally heated catalyst. A different trend emerged when hydrogenation over Pt/Fe3O4 was performed. Compared to conventional heating, the RF increased the selectivity to stearic acid by an additional 15%. Based on these results, RF heating acting upon a magnetically susceptible nanoparticle catalyst would also be expected to positively impact systems with high coking rates, for example, nonoxidative dehydrogenations.

Catalytic Depolymerization of Waste Polyolefins by Induction Heating: Selective Alkane/Alkene Production.

Low- and high-density polyethylene (LDPE/HDPE) have been selectively depolymerized, without added H2, to C2-C20 + alkanes/alkenes via energy-efficient radio frequency induction heating, coupled with dual-functional heterogeneous Fe3O4 and Ni- or Pt-based catalysts. Fe3O4 was used to locally generate heat when exposed to magnetic fields. Initial results indicate that zeolite-based Ni catalysts are more selective to light olefins, while Ni supported on ceria catalysts are more selective to C7-C14 alkanes/alkenes. LDPE conversions up to 94% were obtained with minimal aromatic, coke, or methane formation which are typically observed with thermal heating. Two depolymerization mechanisms, a reverse Cossee-Arlman mechanism or a random cleavage process, were proposed to account for the different selectivities. The depolymerization process was also tested on commercial LDPE (grocery bags), polystyrene, and virgin HDPE using the Ni on Fe3O4 catalyst, with the LDPE resulting in similar product conversion (∼48%) and selectivity as for virgin LDPE.

Fluorescent visualization of oil displacement in a microfluidic device for enhanced oil recovery applications.

A microfluidic device was developed to mimic the reservoir pore-scale and track the oil/water phases during air flooding. The chip was generated by combining soft-lithography and NOA81 replication. A unique feature of this approach is the inclusion of fluorescent dyes into the oil/water phases, allowing for real-time visualization of oil recovery without altering the phases' surface properties. As a proof of concept, the air was injected into the water/oil-flooded device for enhanced oil recovery applications.

Simultaneous Droplet Generation with In-Series Droplet T-Junctions Induced by Gravity-Induced Flow.

Droplet microfluidics offers a wide range of applications, including high-throughput drug screening and single-cell DNA amplification. However, these platforms are often limited to single-input conditions that prevent them from analyzing multiple input parameters (e.g., combined cellular treatments) in a single experiment. Droplet multiplexing will result in higher overall throughput, lowering cost of fabrication, and cutting down the hands-on time in number of applications such as single-cell analysis. Additionally, while lab-on-a-chip fabrication costs have decreased in recent years, the syringe pumps required for generating droplets of uniform shape and size remain cost-prohibitive for researchers interested in utilizing droplet microfluidics. This work investigates the potential of simultaneously generating droplets from a series of three in-line T-junctions utilizing gravity-driven flow to produce consistent, well-defined droplets. Implementing reservoirs with equal heights produced inconsistent flow rates that increased as a function of the distance between the aqueous inlets and the oil inlet. Optimizing the three reservoir heights identified that taller reservoirs were needed for aqueous inlets closer to the oil inlet. Studying the relationship between the ratio of oil-to-water flow rates (Φ) found that increasing Φ resulted in smaller droplets and an enhanced droplet generation rate. An ANOVA was performed on droplet diameter to confirm no significant difference in droplet size from the three different aqueous inlets. The work described here offers an alternative approach to multiplexed droplet microfluidic devices allowing for the high-throughput interrogation of three sample conditions in a single device. It also has provided an alternative method to induce droplet formation that does not require multiple syringe pumps.

Modifying Metastable Sr1-xBO3-δ (B = Nb, Ta, and Mo) Perovskites for Electrode Materials.

The presence of surface/deep defects in 4d- and 5d-perovskite oxide (ABO3, B = Nb, Ta, Mo, etc.) nanoparticles (NPs), originating from multivalent B-site cations, contributes to suppressing their metallic properties. These defect states can be removed using a H2/Ar thermal treatment, enabling the recovery of their electronic properties (i.e., low electrical resistivity, high carrier concentration, etc.) as expected from their electronic structure. Therefore, to engineer the electronic properties of these metastable perovskites, an oxygen-controlled crystallization approach coupled with a subsequent H2/Ar treatment was utilized. A comprehensive study of the effect of the post-treatment time on the electronic properties of these perovskite NPs was performed using a combination of scattering, spectroscopic, and computational techniques. These measurements revealed that a metallic-like state is stabilized in these oxygen-reduced NPs due to the suppression of deep rather than surface defects. Ultimately, this synthetic approach can be employed to synthesize ABO3 perovskite NPs with tunable electronic properties for application into electrochemical devices.

Catalytic Enhancement of Inductively Heated Fe3 O4 Nanoparticles by Removal of Surface Ligands.

Heat management in catalysis is limited by each material's heat transfer efficiencies, resulting in energy losses despite current thermal engineering strategies. In contrast, induction heating of magnetic nanoparticles (NPs) generates heat at the surface of the catalyst where the reaction occurs, reducing waste heat via dissipation. However, the synthesis of magnetic NPs with optimal heat generation requires interfacial ligands, such as oleic acid, which act as heat sinks. Surface treatments using tetramethylammonium hydroxide (TMAOH) or pyridine are used to remove these ligands before applications in hydrophilic media. In this study, Fe3 O4 NPs are surface treated to study the effect of induction heating on the catalytic oxidation of 1-octanol. Whereas TMAOH was unsuccessful in removing oleic acid, pyridine treatment resulted in a roughly 2.5-fold increase in heat generation and product yield. Therefore, efficient surfactant removal has profound implications in induction heating catalysis by increasing the heat transfer and available surface sites.

Effect of Oxide Ion Distribution on a Uranium Structure in Highly U-Doped RE2Hf2O7 (RE = La and Gd) Nanoparticles.

Rare-earth based A2B2O7 compounds have been considered as potential host materials for nuclear waste due to their exceptional chemical, physical, capability of accommodating high concentration of actinides at both A- and B-sites, negligible leaching, tendency to form antisite defects, and radiation stabilities. In this work, La2Hf2O7 (LHO) and Gd2Hf2O7 (GHO) nanoparticles (NPs) were chosen as the RE-based hafnates to study the structural changes and the formation of different U molecular structures upon doping (or alloying) at high concentration (up to 30 mol %) using a combined coprecipitation and molten-salt synthesis. These compounds form similar crystal structures, i.e., ordered pyrochlore (LHO) and disordered fluorite (GHO), but are expected to show different phase transformations at high U doping concentration. X-ray diffraction (XRD) and Rietveld refinement results show that the LHO:U NPs have high structural stability, whereas the GHO:U NPs exhibit a highly disordered structure at high U concentration. Alternatively, the vibrational spectra show an increasingly random oxygen distribution with U doping, driving the LHO:U NPs to the disordered fluorite phase. X-ray spectroscopy indicates that U is stabilized as different U6+ species in both LHO and GHO hosts, resulting in the formation of oxygen vacancies stemming from the U local coordination and different phase transformation. Interestingly, the disordered fluorite phase has been reported to have increased radiation tolerance, suggesting multiple benefits associated with the LHO host. These results demonstrate the importance of the structural and chemical effect of actinide dopants on similar host matrices which are important for the development of RE-based hafnates for nuclear waste hosts, sensors, thermal barrier coatings, and scintillator applications.

Simulated field-modulated x-ray absorption in titania.

In this paper, we present a method to compute the x-ray absorption near-edge structure (XANES) spectra of solid-state transition metal oxides using real-time time-dependent density functional theory, including spin-orbit coupling effects. This was performed on bulk-mimicking anatase titania (TiO2) clusters, which allows for the use of hybrid functionals and atom-centered all electron basis sets. Furthermore, this method was employed to calculate the shifts in the XANES spectra of the Ti L-edge in the presence of applied electric fields to understand how external fields can modify the electronic structure, and how this can be probed using x-ray absorption spectroscopy. Specifically, the onset of t2g peaks in the Ti L-edge was observed to red shift and the eg peaks were observed to blue shift with increasing fields, attributed to changes in the hybridization of the conduction band (3d) orbitals.

Adsorption of Polarized Molecules for Interfacial Band Engineering of Doped TiO2 Thin Films.

Owing to their chemical and mechanical stability, metal-oxides have emerged as potential alternatives for conventional pure-metal and organic molecule-based solid-state electronic devices. Traditionally, band engineering of these metal-oxides has been performed to improve the efficiency of solar cells and transistors. However, recent advancements in the field of oxide-based electronic devices demand reversible band structure engineering for applications in next-generation adaptive electronics and memory devices. Therefore, this work aims to reversibly engineer the surface band structure of doped metal-oxides using stable organic ligands with weak dipoles. Para-substituted benzoic acid (BZA) ligands with positive and negative dipole moments were adsorbed in situ on the surface of TiO2:Ni2+ thin film to modify the interfacial dipole moment, and the valence band structure was probed using surface-sensitive ultraviolet photoelectron spectroscopy (UPS). UPS, paired with density functional theory (DFT) simulations, demonstrate the ability to selectively tune interfacial electronic/chemical landscapes with ligand-dependent dipole moment. The unique ability to reversibly tune the band bending at the organic-inorganic interface of doped metal-oxide semiconductors using molecular dipoles is expected to play a key role in the development of metal-oxide-based adaptive electronics that outperform the conventional polymer-based and Si-based devices.

Critical Coupling of Visible Light Extends Hot-Electron Lifetimes for H2O2 Synthesis.

Devices driven by above-equilibrium "hot" electrons are appealing for photocatalytic technologies, such as in situ H2O2 synthesis, but currently suffer from low (<1%) overall quantum efficiencies. Gold nanostructures excited by visible light generate hot electrons that can inject into a neighboring semiconductor to drive electrochemical reactions. Here, we designed and studied a metal-insulator-metal (MIM) structure of Au nanoparticles on a ZnO/TiO2/Al film stack, deposited through room-temperature, lithography-free methods. Light absorption, electron injection efficiency, and photocatalytic yield in this device are superior in comparison to the same stack without Al. Our device absorbs >60% of light at the Au localized surface plasmon resonance (LSPR) peak near 530 nm-a 5-fold enhancement in Au absorption due to critical coupling to an Al film. Furthermore, we show through ultrafast pump-probe spectroscopy that the Al-coupled samples exhibit a nearly 5-fold improvement in hot-electron injection efficiency as compared to a non-Al device, with the hot-electron lifetimes extending to >2 ps in devices photoexcited with fluence of 0.1 mJ cm-2. The use of an Al film also enhances the photocatalytic yield of H2O2 more than 3-fold in a visible-light-driven reactor. Altogether, we show that the critical coupling of Al films to Au nanoparticles is a low-cost, lithography-free method for improving visible-light capture, extending hot-carrier lifetimes, and ultimately increasing the rate of in situ H2O2 generation.

Role of Ce in Manipulating the Photoluminescence of Tb Doped Y2Zr2O7.

Y2Zr2O7 (YZO) is widely used as a host material for luminescent centers because of its high stability and the ability to accommodate anion defects. In this work, the effects of Ce and Tb doping on the photoluminescence (PL) properties of YZO nanoparticles (NPs) are studied in detail to correlate the emission intensity with the dopant concentration. Herein, a two-step synthesis method of coprecipitation and molten salt was employed to prepare the YZO:Tb,Ce NPs. The single doped YZO:Tb (2 mol %) NPs shows a strong Tb3+ emission. However, after codoping with Ce ions, the Tb3+ emission is quenched instead of the expected sensitization. To identify the mechanism of quenching (oxidation state/local symmetry), X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) were performed. The Ce4+ ions were observed to drive further oxidation of Tb to a nonluminescent +4 oxidation state. Alternatively, Eu3+ was employed to probe local symmetry changes upon Ce doping. The asymmetry ratio of the magnetic and electronic transitions indicates that the Ce dopant also pushes the system into a higher symmetry, resulting in two separate quenching mechanisms.

Dipole-Modulated Downconversion Nanoparticles as Label-Free Biological Sensors.

Ultrasensitive detection of proteins and biomolecules has been previously achieved by optical nanoparticles (NPs) using the principles of Förster resonance energy transfer (FRET). However, the inherent need for labeling the target analyte in these assays hinders their applicability in point-of-use (POU) diagnostics. In this work, a label-free NP-based sensor has been developed that utilizes downconversion luminescence and surface electric dipoles as a novel approach for the detection of avidin. The long-lived luminescence of Eu3+-doped biotinylated NPs was effectively quenched in the presence of avidin in a concentration-dependent manner. The NPs exhibited high avidin selectivity and sensitivity with a limit of detection (LOD) of 7.8 nM and a wide dynamic range spanning 1 nM to 10 µM in deionized (DI) water. The application of the assay in a complex biological matrix consisting of cell growth medium supplemented with 10% v/v serum was verified with minor effects on avidin sensitivity exhibited by an LOD of 34.7 nM. The performance of the system was evaluated by comparing the photoluminescence (PL) intensities of known avidin concentration and the values predicted by the generated calibration curve. The new biosensing strategy has the potential to be extended to the detection of other disease biomarkers or pathogens with LOD and limited matrix effects in POU settings.

Stabilizing the B-site oxidation state in ABO3 perovskite nanoparticles.

The stabilization of the B-site oxidation state in ABO3 perovskites using wet-chemical methods is a synthetic challenge, which is of fundamental and practical interest for energy storage and conversion devices. In this work, defect-controlled (Sr-deficiency and oxygen vacancies) strontium niobium(iv) oxide (Sr1-xNbO3-δ, SNO) metal oxide nanoparticles (NPs) were synthesized for the first time using a low-pressure wet-chemistry synthesis. The experiments were performed under reduced oxygen partial pressure to prevent by-product formation and with varying Sr/Nb molar ratio to favor the formation of Nb4+ pervoskites. At a critical Sr to Nb ratio (Sr/Nb = 1.3), a phase transition is observed forming an oxygen-deficient SrNbO3 phase. Structural refinement on the resultant diffraction pattern shows that the SNO NPs consists of a near equal mixture of SrNbO3 and Sr0.7NbO3-δ crystal phases. A combination of Rietveld refinement and X-ray photoelectron spectroscopy (XPS) confirmed the stabilization of the +4 oxidation state and the formation of oxygen vacancies. The Nb local site symmetry was extracted through Raman spectroscopy and modeled using DFT. As further confirmation, the particles demonstrate the expected absorption highlighting their restored optoelectronic properties. This low-pressure wet-chemical approach for stabilizing the oxidation state of a transition metal has the potential to be extended to other oxygen sensitive, low dimensional perovskite oxides with unique properties.

Luminescent nanomaterials for droplet tracking in a microfluidic trapping array.

The use of high-throughput multiplexed screening platforms has attracted significant interest in the field of on-site disease detection and diagnostics for their capability to simultaneously interrogate single-cell responses across different populations. However, many of the current approaches are limited by the spectral overlap between tracking materials (e.g., organic dyes) and commonly used fluorophores/biochemical stains, thus restraining their applications in multiplexed studies. This work demonstrates that the downconversion emission spectra offered by rare earth (RE)-doped ß-hexagonal NaYF4 nanoparticles (NPs) can be exploited to address this spectral overlap issue. Compared to organic dyes and other tracking materials where the excitation and emission is separated by tens of nanometers, RE elements have a large gap between excitation and emission which results in their spectral independence from the organic dyes. As a proof of concept, two differently doped NaYF4 NPs (europium: Eu3+, and terbium: Tb3+) were employed on a fluorescent microscopy-based droplet microfluidic trapping array to test their feasibility as spectrally independent droplet trackers. The luminescence tracking properties of Eu3+-doped (red emission) and Tb3+-doped (green emission) NPs were successfully characterized by co-encapsulating with genetically modified cancer cell lines expressing green or red fluorescent proteins (GFP and RFP) in addition to a mixed population of live and dead cells stained with ethidium homodimer. Detailed quantification of the luminescent and fluorescent signals was performed to confirm no overlap between each of the NPs and between NPs and cells. Thus, the spectral independence of Eu3+-doped and Tb3+-doped NPs with each other and with common fluorophores highlights the potential application of this novel technique in multiplexed systems, where many such luminescent NPs (other doped and co-doped NPs) can be used to simultaneously track different input conditions on the same platform. Graphical abstract ᅟ.