| 1. |
- Archer, W. E., et al.
(author)
-
Steve : The Optical Signature of Intense Subauroral Ion Drifts
- 2019
-
In: Geophysical Research Letters. - : AMER GEOPHYSICAL UNION. - 0094-8276 .- 1944-8007. ; 46:12, s. 6279-6286
-
Journal article (peer-reviewed)abstract
- Little is currently known about the optical phenomenon known as Steve. The first scientific publication on the subject suggests that Steve is associated with an intense subauroral ion drift (SAID). However, additional inquiry is warranted as this suggested relationship as it is based on a single case study. Here we present eight occurrences of Steve with coincident or near-coincident measurements from the European Space Agency's Swarm satellites and show that Steve is consistently associated with SAID. When satellite observations coincident with Steve are compared to that of typical SAID, we find the SAID associated with Steve to have above average peak ion velocities and electron temperatures, as well as extremely low plasma densities.
|
|
| 2. |
- Babucci, Melike, et al.
(author)
-
Depth-Dependent Atomic-Scale Structural Changes in (Ag,Cu)(In,Ga)Se2 Absorbers Relevant for Thin-Film Solar Cells
- 2023
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 6:18, s. 9264-9275
-
Journal article (peer-reviewed)abstract
- Alloying a Cu(In,Ga)Se-2 (CIGS) solar cell absorber with silver to form (Ag,Cu)(In,Ga)Se-2 (ACIGS) is an effective route for improving the performance of CIGS-based thin-film solar cells by increasing the optical band gap and open-circuit voltage. While the role of Ag on the solar cell's performance and crystal structure has been analyzed, important gaps in our understanding remain, especially regarding the atomistic (short-range) structure. Previous X-ray absorption spectroscopy (XAS) results have shown that local atomic arrangements in Ag-free CIGS deviate from the long-range crystallographic structure deduced from X-ray diffraction (XRD). However, it is unclear how these structural deviations evolve with Ag alloying, particularly in the presence of Ga depth gradient. In this work, we employ angle-resolved XAS to probe the local environment of Se atoms within different depths of ACIGS absorbers with varying Ag content and Ga depth gradient. By complementing XAS results with X-ray diffraction measurements for long-range structures, glow discharge optical emission spectroscopy for elemental profiles, and scanning transmission electron microscopy for morphologies, changes in element-specific bond lengths, cell parameters, and anion displacement depending on compositions of Group [I] (Cu, Ag) and Group [III] (In, Ga) elements were mapped. The results suggest that the local atomic arrangement of the investigated ACIGS thin-film solar cell samples is depth-dependent and deviates from the long-range crystallographic structure. Possible reasons include tetragonal distortion or the presence of other phases or off-stoichiometry compounds. For the sample with the highest Ag content, increased bond lengths of Se-Group [I] atoms and Se-Ga are observed from the absorber bulk toward the near-absorber/buffer interface, whereas, in Ag-free CIGS, no significant changes are found. Results further indicate nonlinear anion displacement with Ag addition in the absorber bulk or with depth composition variation, which is likely to affect the electronic properties of solar cells. These findings offer a better understanding of the atomic-scale properties of ACIGS absorbers in actual thin-film solar cells containing in-depth composition variations.
|
|
| 3. |
- Babula, Oksana, et al.
(author)
-
Altered distribution of mannose-binding lectin alleles at exon I codon 54 in women with vulvar vestibulitis syndrome
- 2004
-
In: American Journal of Obstetrics and Gynecology. - St Louis : Mosby. - 0002-9378 .- 1097-6868. ; 191:3, s. 762-766
-
Journal article (peer-reviewed)abstract
- Objectives: Mannose-binding lectin (MBL) is active in the innate immune defense against microorganisms. In this study, we determined whether vulvar vestibulitis syndrome, a disorder of unknown etiology, was associated with an altered distribution of MBL alleles.Study design: Buccal swabs were obtained from women with vulvar vestibulitis syndrome in New York (62) and from 2 cities in Sweden (60), as well as control women in New York (48) and Sweden (51). DNA was tested for a single nucleotide polymorphism at codon 54 in exon I by polymerase chain reaction, endonuclease digestion, and gel electrophoresis. Blood samples were also obtained from the New York women and tested by ELISA for plasma MBL concentrations. The relationships between genotype, allele frequencies, blood MBL levels, and diagnosis were analyzed by Fisher exact test and one-way analysis of variance.Results: The variant MBL allele, MBL*B, was detected in 35.5% and 26.7% of vulvar vestibulitis patients from New York and Sweden, respectively. Only 12.5% of New York controls (P = .007) and 9.8% of Swedish controls (P = .01) were MBL*2-positive. All women, with one exception, who were positive for MBL*B were MBL*A/MBL*B heterozygotes. Women who carried MBL*B had almost a 10-fold reduction in median plasma MBL concentrations (278 ng/mL), as opposed to women who were MBL*A homozygotes (1980 ng/mL) (P < .0001).Conclusion: MBL*B carriage and reduced plasma MBL levels are more common in women with vulvar vestibulitis syndrome than in control patients, and may contribute to symptomatology in a subset of patients.
|
|
| 4. |
|
|
| 5. |
- Babucci, Melike, et al.
(author)
-
Atomically Dispersed Metals on Well-Defined Supports including Zeolites and Metal–Organic Frameworks: Structure, Bonding, Reactivity, and Catalysis
- 2020
-
In: Chemical Reviews. - : American Chemical Society (ACS). - 0009-2665 .- 1520-6890. ; 120:21, s. 11956-11985
-
Journal article (peer-reviewed)abstract
- When metals in supported catalysts are atomically dispersed, they are usually cationic and bonded chemically to supports. Investigations of noble metals in this class are growing rapidly, leading to discoveries of catalysts with new properties. Characterization of these materials is challenging because the metal atoms reside on surfaces that are typically nonuniform in composition and structure. We posit that understanding of structures and catalytic properties of these materials is emerging most strongly from investigations of structurally uniform catalysts (metal atoms dispersed on crystalline supports) which can be characterized incisively with atomic-resolution electron microscopy, X-ray absorption spectroscopy, and infrared spectroscopy, bolstered by density functional theory. We assess the literature of such catalysts supported on zeotype materials, metal-organic frameworks, and covalent organic frameworks. Assessing characterization, reactivity, and catalytic performance of catalysts for oxidation, hydrogenation, the water-gas shift reaction, and others, we consider metal-support interactions and ligand effects for various metal-support combinations, evaluating the degree of structural uniformity of exemplary catalysts and summarizing structure-reactivity and structure-catalytic property relationships.
|
|
| 6. |
|
|
| 7. |
- Babucci, Melike, et al.
(author)
-
Interactions of [BMIM][BF4] with Metal Oxides and Their Consequences on Stability Limits
- 2016
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:36, s. 20089-20102
-
Journal article (peer-reviewed)abstract
- Interactions between 1-n-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4], and high-surface-area metal oxides, SiO2, TiO2, Fe2O3, ZnO, gamma-Al2O3, CeO2, MgO, and La2O3, covering a wide range of point of zero charges (PZC), from pH = 2 to 11, were investigated by combining infrared (IR) spectroscopy with density functional theory (DFT) calculations. The shifts in spectroscopic features of the ionic liquid (IL) upon coating different metal oxides were evaluated to elucidate the interactions between IL and metal oxides as a function of surface acidity. Consequences of these interactions on the short- and long-term thermal stability limits as well as the apparent activation energy (Ea) and rate constant for thermal decomposition of the supported IL were evaluated. Results showed that stability limits and Ea of the IL on each metal oxide significantly decrease with increasing PZC of the metal oxide. Results presented here indicate that the surface acidity strongly controls the IL surface interactions, which determine the material properties, such as thermal stability. Elucidation of these effects offers opportunities for rational design of materials which include direct interactions of ILs with metal oxides, such as solid catalysts with ionic liquid layer (SCILL), and supported ionic liquid phase (SILP) catalysts for catalysis applications or supported ionic liquid membranes (SILM) for separation applications.
|
|
| 8. |
- Babucci, Melike, et al.
(author)
-
Tuning the Selectivity of Single-Site Supported Metal Catalysts with Ionic Liquids
- 2017
-
In: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 7:10, s. 6969-6972
-
Journal article (peer-reviewed)abstract
- 1,3-Dialkylimidazolium ionic liquid coatings act as electron donors, increasing the selectivity for partial hydrogenation of 1,3-butadiene catalyzed by iridium complexes supported on high-surface-area gamma-Al2O3. High-energy-resolution fluorescence detection X-ray absorption near-edge structure (HERFD XANES) measurements quantify the electron donation and are correlated with the catalytic activity and selectivity. The results demonstrate broad opportunities to tune electronic environments and catalytic properties of atomically dispersed supported metal catalysts.
|
|
| 9. |
- Babucci, Melike, et al.
(author)
-
Unraveling the individual influences of supports and ionic liquid coatings on the catalytic properties of supported iridium complexes and iridium clusters
- 2020
-
In: Journal of Catalysis. - : Elsevier BV. - 0021-9517 .- 1090-2694. ; 387, s. 186-195
-
Journal article (peer-reviewed)abstract
- Supported iridium complexes were synthesized by the reaction of Ir(CO)(2) (acac) (acac = acetylacetonato) with SiO2, gamma-Al2O3, and MgO. Extended X-ray absorption fine structure (EXAFS) and infrared (IR) spectra demonstrate that the iridium was present as atomically dispersed species anchored to each support. The samples were treated in flowing H-2 at 673 K to form supported iridium clusters. EXAFS spectra and highangle annular dark-field scanning transmission electron microscopy images demonstrate that the average diameter of the iridium clusters on each support was approximately 1.2 nm. The catalysts before and after cluster formation were coated with each of a family of 1,3-dialkylimidazolium ionic liquids (ILs) having varying electron-donor tendencies probed by their nu(C2H) frequencies determined by IR spectroscopy. The coated and uncoated samples were tested as catalysts for partial hydrogenation of 1,3-butadiene in a flow reactor at 333 K, with turnover frequencies determined from differential conversions. The individual influences of the IL coatings and supports on the catalyst performance were found to depend strongly on whether the iridium was site-isolated complexes or present in clusters. The IL coatings as ligands exerted dominant effects on the clusters as catalysts, whereas the supports exerted dominant effects on the isolated iridium atoms. The results indicate how to tune the effects of metal nuclearity, IL coatings, and supports on the electronic environments and catalytic properties of the metals
|
|
| 10. |
|
|
