The effect of uranium on bacterial viability and cell surface morphology using atomic force microscopy in the presence of bicarbonate ions
Not Available
Sepulveda-Medina, Paola↗
SEARCH · Engineering Papers
Results for “cells”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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The Cell Utilized Partitioning Model as a Predictive Tool for Optimizing Counter-Current Chromatography Processes
Counter-current chromatography (CCC) is capable of unique elution modes that isolate analytes using the movement of the stationary phase in addition to moving the mobile phase. These modes include elution-extrusion CCC (EECCC) and dual-mode CCC (DM CCC) that are not possible in traditional solid-liquid chromatography systems. Although EECCC and DM CCC are widely used to recover highly retained components, to our knowledge, optimizing the elution process in these modes with predictive models has not been reported. To address this gap, we developed a predictive model for CCC dubbed the Cell Utilized Partitioning (CUP) model. The CUP model accurately predicts the effluents of multicomponent separations in EECCC and DM CCC modes when compared to experimental data. Furthermore, CUP model simulations were extended to investigate the influence of operating and intrinsic parameters on the yield and productivity, and to compare the separation performances of EECCC and DM CCC in various conditions. The results demonstrate that low distribution constants, usually a KD less than 1, and a selectivity > 1.3, under specific flowrate ranges, increase both productivity and yield. From these results, generalized optimization and scaleup guidelines are proposed that can apply to research settings and to industrial processes to maximize preparative CCC performance.
BIOMASS FUELS,INORGANIC, ORGANIC, PHYSICAL, AND AN↗
cxcl12 gene engineered endothelial progenitor cells further improve the functions of oligodendrocyte precursor cells
Highlights: • cxcl12 gene engineering of EPCs promoted VEGF and IGF expression by EPCs. • Conditioned media from CXCL12-EPCs further promoted the functions of OPCs. • CXCL12-EPCs conditioned media affected the expression of trophic factors by OPCs. • CXCR4 knockdown suppressed the proliferation and migration of OPCs and reduced PDGFR-α and bFGF expression. • CXCR7 knockdown inhibited the expression of MBP by OPCs and caused slower differentiation. Oligodendrocyte precursor cells (OPCs) are needed for white matter repair after various brain injury. Means that promote OPC functions could benefit white matter recovery after injury. Chemokine CXCL12 and endothelial progenitor cells (EPCs) both have been shown to promote remyelination. We hypothesize that the beneficial effects of EPCs and CXCL12 can be harnessed by genetically modifying EPCs with cxcl12 to synergistically improve the functions of OPCs. In this work, CXCL12-EPC was generated using virus-mediated gene transfer. OPCs were cultured with CXCL12-EPC conditioned media (CM) to analyze its impact on the proliferation, migration, differentiation and survival properties of OPCs. We blocked or knocked-down the receptors of CXCL12, namely CXCR4 and CXCR7, respectively to investigate their functions in regulating OPCs properties. Results revealed that CXCL12-EPC CM further promoted OPCs behavioral properties and upregulated the expression of PDGFR-α, bFGF, CXCR4 and CXCR7 in OPCs, albeit following different time course. Blocking CXCR4 diminished the beneficial effects of CXCL12 on OPCs proliferation and migration, while knocking down CXCR7 inhibited OPCs differentiation. Our results supported that cxcl12 gene modification of EPCs further promoted EPCs’ ability in augmenting the remyelination properties of OPCs, suggesting that CXCL12-EPC hold great potential in white matter repair.
60 APPLIED LIFE SCIENCES↗
TRIM46 contributes to high glucose-induced ferroptosis and cell growth inhibition in human retinal capillary endothelial cells by facilitating GPX4 ubiquitination
Increased permeability of retinal capillary endothelial cells is a key feature in the progression of diabetic retinopathy (DR). Precisely why and how diabetes causes dysfunction in retinal capillary endothelial cells is not well understood, making it challenging to explore more advanced therapeutics.
60 APPLIED LIFE SCIENCES↗
Mechanically induced localisation of SECONDARY WALL INTERACTING bZIP is associated with thigmomorphogenic and secondary cell wall gene expression
Plant growth requires the integration of internal and external cues, perceived and transduced into a developmental programme of cell division, elongation and wall thickening. Mechanical forces contribute to this regulation, and thigmomorphogenesis typically includes reducing stem height, increasing stem diameter, and a canonical transcriptomic response. We present data on a bZIP transcription factor involved in this process in grasses. Brachypodium distachyon SECONDARY WALL INTERACTING bZIP (SWIZ) protein translocated into the nucleus following mechanostimulation. Classical touch-responsive genes were upregulated in B. distachyon roots following touch, including significant induction of the glycoside hydrolase 17 family, which may be unique to grass thigmomorphogenesis. SWIZ protein binding to an E-box variant in exons and introns was associated with immediate activation followed by repression of gene expression. SWIZ overexpression resulted in plants with reduced stem and root elongation. These data further define plant touch-responsive transcriptomics and physiology, offering insights into grass mechanotranduction dynamics.
Coomey, Joshua↗
A (S)TEM Gas Cell Holder with Localized Laser Heating for In Situ Experiments
The advent of aberration correction for transmission electron microscopy has transformed atomic resolution imaging into a nearly routine technique for structural analysis. Now an emerging frontier in electron microscopy is the development of in situ capabilities to observe reactions at atomic resolution in real time and within realistic environments. Here we present a new in situ gas cell holder that is designed for compatibility with a wide variety of sample type (i.e., dimpled 3-mm discs, standard mesh grids, various types of focused ion beam lamellae attached to half grids). Its capabilities include localized heating and precise control of the gas pressure and composition while simultaneously allowing atomic resolution imaging at ambient pressure. The results show that 0.25-nm lattice fringes are directly visible for nanoparticles imaged at ambient pressure with gas path lengths up to 20 μm. Additionally, we quantitatively demonstrate that while the attainable contrast and resolution decrease with increasing pressure and gas path length, resolutions better than 0.2 nm should be accessible at ambient pressure with gas path lengths less than the 15 μm utilized for these experiments.
aberration correction↗
Impact of Sr-Containing Secondary Phases on Oxide Conductivity in Solid-Oxide Electrolyzer Cells
Solid-oxide electrolyzer cells (SOECs) based on a yttria-stabilized zirconia (YSZ) oxide electrolyte produce hydrogen from water with the assistance of excess thermal energy; however, Sr diffusion within the Gd-doped CeO 2 (GDC) barrier layer during processing or operation can lead to the formation of unwanted secondary phases such as SrO and SrZrO 3 . Here, to establish and compare the degree of impact of these phases on SOEC performance, we conduct first-principles calculations to study their bulk oxide conductivities and compare them to that of the YSZ electrolyte. We find that SrO has a low conductivity arising from the poor mobility and low concentration of mobile oxygen vacancies, and its presence in SOECs should therefore be avoided. SrZrO 3 also has a lower oxide conductivity than YSZ; however, this discrepancy is primarily due to lower vacancy concentrations rather than low mobility. We find that sufficient levels of Y-doping on the Zr site can increase oxygen vacancy concentrations in SrZrO 3 to achieve an oxide ionic conductivity on par with that of YSZ, thereby mitigating any potential deleterious effect on transport performance. Energy-dispersive X-ray spectroscopy confirms that Y is the most common minority element present in SrZrO 3 forming near the GDC–YSZ interface, alleviating concerns regarding the impact of SrZrO 3 on device performance. These results from our combined computational–experimental analysis can inform future engineering strategies designed to limit the detrimental effects of Sr-induced secondary phase formation on SOEC performance.
08 HYDROGEN↗
Improving Solar Cell Performance Using Quantum Dot Triad Charge-Separation Engines
Here, we use kinetic modeling to explore the current–voltage, power–voltage, and power conversion efficiency characteristics of quantum dot dyads and triads as possible light absorption and charge separation engines in quantum dot, bulk heterojunction solar cells. The external and internal power conversion quantum efficiencies are significantly enhanced by introducing a third quantum dot between the donor and acceptor quantum dots. Given the constraint of comparable charge-recombination and charge-separation rates, open-circuit voltages for triads are predicted to be about 10%–17% larger than those for dyads, and short-circuit currents for triads are about 400% larger than those for dyads. These improvements in the efficiencies can be further enhanced by tuning the band-edge energy offset of the middle-position quantum dot from its neighbors. The band-edge energies of the middle quantum dot should be tuned so that they form a cascading band-edge energy alignment from the band-edge energies of the left CdTe QD to the right CdSe QD. To produce the most favorable solar cell performance, the middle quantum dot’s conduction (valence) band edge should be closer to the right quantum dot’s band edge when the charge recombination rates are low (high) and near the conduction (valence) band edge of the left quantum dot when the charge recombination rates are high (low). This analysis identifies prime strategies to design multi-QD assemblies for solar energy harvesting and conversion.
36 MATERIALS SCIENCE↗
Chemical Bath Deposition of p-Type Transparent, Highly Conducting (CuS) x :(ZnS) 1– x Nanocomposite Thin Films and Fabrication of Si Heterojunction Solar Cells
Explore the source record for details and available documents.
Xu, Xiaojie↗
Readily Accessible Benzo[d]thiazole Polymers for Nonfullerene Solar Cells with >16% Efficiency and Potential Pitfalls
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99 GENERAL AND MISCELLANEOUS↗
Surface-Activated Corrosion in Tin–Lead Halide Perovskite Solar Cells
Mixed tin–lead halide perovskite solar cells have promising power conversion efficiencies, but long-term stability is still a challenge. Here, we examine the stability of a 60:40 tin–lead perovskite to better understand diminished device performance upon thermal treatment, both in ambient and inert atmosphere. Operando X-ray diffraction shows a stable bulk structure of the perovskite absorber, leading to the hypothesis that surface chemistry dominates the degradation mechanism. X-ray photoelectron spectroscopy reveals two new observations post-thermal annealing that accompany previously reported Sn 4+ evolution: (i) the formation of I 3 – intermediates preceding I 2 loss at the surface and (ii) evidence of under-coordinated tin and lead surface sites (Sn δ<2+ and Pb δ<2+ , respectively) in inert and ambient conditions. These two species indicate an activated corrosion (i.e., both oxidation and reduction) process at the surface as a possible chemical pathway for degradation, which is expected to be accelerated under operando voltage and light biases.
14 SOLAR ENERGY↗
Formation of a C15 Laves Phase with a Giant Unit Cell in Salt-Doped A/B/AB Ternary Polymer Blends
Abstract not provided
Xie, Shuyi↗
Layer-by-Layer Molecular Assemblies for Dye-Sensitized Photoelectrosynthesis Cells Prepared by Atomic Layer Deposition
In a Dye Sensitized Photoelectrosynthesis Cell (DSPEC) the relative orientation of catalyst and chromophore play important roles. Here we introduce a new, robust, Atomic Layer Deposition (ALD) procedure for the preparation of assemblies on wide bandgap semiconductors. In the procedure, phosphonated metal complex precursors react with metal ion bridging to an external chromophore or catalyst to give assemblies bridged by Al(III), Sn(IV), Ti(IV), or Zr(IV) metal oxide units as bridges. The procedure has been extended to chromophore-catalyst assemblies for water oxidation catalysis. A SnO2 bridged assembly on SnO2/TiO2 core/shell electrodes undergoes water splitting with an incident photon conversion efficiency (IPCE) of 17.1% at 440 nm. Reduction of water at a Ni(II)-based catalyst on NiO films has been shown to give H2. Compared to conventional solution-based procedures, the ALD approach offers significant advantages in scope and flexibility for the preparation of stable surface structures.
DSPEC, core/shell, Atomic Layer Deposition, self-a↗
Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells
Electricity produced by cadmium telluride (CdTe) photovoltaic modules is the lowest-cost electricity in the solar industry, and now undercuts fossil fuel-based sources in many regions of the world. This is due to recent efficiency gains brought about by alloying selenium into the CdTe absorber, which has taken cell efficiency from 19.5% to its current record of 22.1%. Although the addition of selenium is known to reduce the bandgap of the absorber material, and hence increase the cell short-circuit current, this effect alone does not explain the performance improvement. Here, by means of cathodoluminescence and secondary ion mass spectrometry, we show that selenium enables higher luminescence efficiency and longer diffusion lengths in the alloyed material, indicating that selenium passivates critical defects in the bulk of the absorber layer. Here, this passivation effect explains the record-breaking performance of selenium-alloyed CdTe devices, and provides a route for further efficiency improvement that can result in even lower costs for solar-generated electricity.
14 SOLAR ENERGY↗
Designer membraneless organelles sequester native factors for control of cell behavior
Subcellular compartmentalization of macromolecules increases flux and prevents inhibitory interactions to control biochemical reactions. Inspired by this functionality, we sought to build designer compartments that function as hubs to regulate the flow of information through cellular control systems. Here we report a synthetic membraneless organelle platform to control endogenous cellular activities through sequestration and insulation of native proteins. We engineer and express a disordered protein scaffold to assemble micron size condensates and recruit endogenous clients via genomic tagging with high-affinity dimerization motifs. By relocalizing up to ninety percent of a targeted enzymes to synthetic condensates, we efficiently control cellular behaviors, including proliferation, division, and cytoskeletal organization. Further, we demonstrate multiple strategies for controlled cargo release from condensates to switch cells between functional states. These synthetic organelles offer a powerful and generalizable approach to modularly control cell decision-making in a variety of model systems with broad applications for cellular engineering.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Experimental demonstration of enhanced photon recycling in angle-restricted GaAs solar cells
Enhanced open-circuit voltage demonstrated in a high quality GaAs solar cell by limiting the angles of emitted light from the cell.
solar (photovoltaic), solid state lighting, phonon↗
Guided Crystallization of P3HT in Ternary Blend Solar Cell Based on P3HT:PCPDTBT:PCBM
To mimic the performance of the tandem solar cells, ternary blend solar cells with a single active layer of P3HT:PCPDTBT:PC61BM were cast from chlorobenzene and thermally annealed. By varying blending ratio, thermal annealing time and P3HT molecular weight, the device performance was enhanced relative to the binary references.For further understanding, the morphology of the active layer was studied using hard and soft X-ray scattering methods in concert with bright field and energy resolved transmission electron microscopies. We found that the phase separation of the amorphous PCPDTBT and P3HT guided the formation of P3HT fibrils, resulting in a unique multi-length-scale morphology. This morphology consisted of bundles of well-defined P3HT fibrils, forming a network, imbedded in an amorphous mixture of the PCBM, PCPDTBT and P3HT. The two polymers acted independently in their specific photoactive ranges, and the sensitization of PCPDTBT benefited the cascade charge transfer. In addition, this multi-length-scale morphology was linked to the improved device performance of P3HT:PCPDTBT:PC 61 BM and the photophysics of the active layer.
14 SOLAR ENERGY↗
Probing Battery Chemistry with Liquid Cell Electron Energy Loss Spectroscopy
We demonstrate the ability to apply electron energy loss spectroscopy (EELS) to follow the chemistry and oxidation states of LiMn 2 O 4 and Li 4 Ti 5 O1 2 battery electrodes within a battery solvent. The use and importance of in situ electrochemical cells coupled with a scanning/transmission electron microscope (S/TEM) has expanded and been applied to follow changes in battery chemistry during electrochemical cycling. Furthermore, we discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies.
25 ENERGY STORAGE↗