Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS

We have studied atomic level interactions between single Pt atoms and the surface of monolayer MoS₂ using aberration-corrected annular dark field scanning transmission electron microscopy at an accelerating voltage of 60 kV. Strong contrast from single Pt atoms on the atomically resolved monolayer MoS₂ lattice enables their exact position to be determined with respect to the MoS₂ lattice, revealing stable binding sites. In regions of MoS₂ free from surface contamination, the Pt atoms are localized in S vacancy sites and exhibit dynamic hopping to nearby vacancy sites driven by the energy supplied by the electron beam. However, in areas of MoS₂ contaminated with carbon surface layers, the Pt atoms appear at various positions with respect to the underlying MoS₂ lattice, including on top of Mo and in off-axis positions. These variations are due to the Pt bonding with the surrounding amorphous carbon layer, which disrupts the intrinsic Pt-MoS₂ interactions, leading to more varied positions. Density functional theory (DFT) calculations reveal that Pt atoms on the surface of MoS₂ have a small barrier for migration and are stabilized when bound to either a single or double sulfur vacancies. DFT calculations have been used to understand how the catalytic activity of the MoS₂ basal plane for hydrogen evolution reaction is influenced by Pt dopants by variation of the hydrogen adsorption free energy. This strong dependence of catalytic effect on interfacial configurations is shown to be common for a series of dopants, which may provide a means to create and optimize reaction centers

On a matrix group constructed from an {R,s+1,k}-potent matrix

Let R∈C^(n×n) be a {k}-involutory matrix (that is, R^k=I_n) for some integer k≥2, and let s be a nonnegative integer. A matrix A∈C^(n×n) is called an {R,s+1,k}-potent matrix if A satisfies R A = A^(s+1) R. In this paper, a matrix group corresponding to a fixed {R,s+1,k}-potent matrix is explicitly constructed, and properties of this group are derived and investigated. This group is then reconciled with the classical matrix group G_A that is associated with a generalized group invertible matrix A. Let R∈Cn×n be a {k}-involutory matrix (that is, Rk=In) for some integer k≥2, and let s be a nonnegative integer. A matrix A∈Cn×n is called an {R,s+1,k}-potent matrix if A satisfies RA=As+1R. In this paper, a matrix group corresponding to a fixed {R,s+1,k}-potent matrix is explicitly constructed, and properties of this group are derived and investigated. This group is then reconciled with the classical matrix group GA that is associated with a generalized group invertible matrix A

Toxoplasmosis-Related Knowledge and Practices Among Pregnant Women in the United States

Background: Infection with Toxoplasma gondii during pregnancy can lead to severe illness in the fetus. Many T. gondii infections are preventable by simple hygienic measures. Methods: We surveyed pregnant women in the US to determine their knowledge about toxoplasmosis and their practices to prevent infection. Volunteer obstetricians selected to be demographically representative of the American College of Obstetricians and Gynecologists recruited the participants. Results: Of 403 women responding to the survey, 48% indicated that they had heard or seen information about toxoplasmosis; however, only 7% were aware of being tested for the disease. Forty percent of responding women knew that toxoplasmosis is caused by an infection, but 21% thought that a poison causes it. The highest level of knowledge was about cats and T. gondii ; 61% responded that the organism is shed in the feces of infected cats and 60% responded that people could acquire toxoplasmosis by changing cat litter. There was a low level of knowledge about other risk factors; only 30% of the women were aware that T. gondii may be found in raw or undercooked meat. Nevertheless, a high percentage of women indicated that they do not eat undercooked meat during pregnancy and that they practice good hygienic measures such as washing their hands after handling raw meat, gardening or changing cat litter. Conclusion: Except for the risk of transmission from cats, knowledge among pregnant women about toxoplasmosis is low. However, toxoplasmosis-preventive practices are generally good, suggesting that providers should continue to offer education about practices that help prevent foodborne diseases in general as well as information about preventing toxoplasmosis specifically

Partial inhibition of mitochondrial complex I ameliorates Alzheimer\u27s disease pathology and cognition in APP/PS1 female mice.

Alzheimer\u27s Disease (AD) is a devastating neurodegenerative disorder without a cure. Here we show that mitochondrial respiratory chain complex I is an important small molecule druggable target in AD. Partial inhibition of complex I triggers the AMP-activated protein kinase-dependent signaling network leading to neuroprotection in symptomatic APP/PS1 female mice, a translational model of AD. Treatment of symptomatic APP/PS1 mice with complex I inhibitor improved energy homeostasis, synaptic activity, long-term potentiation, dendritic spine maturation, cognitive function and proteostasis, and reduced oxidative stress and inflammation in brain and periphery, ultimately blocking the ongoing neurodegeneration. Therapeutic efficacy in vivo was monitored using translational biomarkers FDG-PET, 31P NMR, and metabolomics. Cross-validation of the mouse and the human transcriptomic data from the NIH Accelerating Medicines Partnership-AD database demonstrated that pathways improved by the treatment in APP/PS1 mice, including the immune system response and neurotransmission, represent mechanisms essential for therapeutic efficacy in AD patients

The surface chemistry of near-infrared resonant gold nanotriangles obtained via thiosulfate synthesis

Gold nanoparticles with NIR absorption are promising for photothermal therapy applications. Different syntheses have been proposed and, among them, that based on the reduction of Au(III) with thiosulfate is important because it yields gold nanotriangles (AuNTs) with strong absorption in the near-infrared region. It has been previously reported by others that the nanoparticle surface is covered by relatively weak adsorbed S species (mostly sulfate), which would render the surface easy to functionalize in order to improve biocompatibility and therapeutic effects. In this work we have used XPS, XANES, UV–vis–NIR spectroscopy, HRTEM and AFM to demonstrate that, in contrast to the previous reports, these AuNTs are covered by strongly adsorbed sulfur species (sulfide and polysulfide). A reaction pathway is proposed to explain the presence of reduced sulfur species and the absence of adsorbed sulfates and thiosulfates. Preliminary cytotoxicity assays show that the S-capped AuNTs do not show a deleterious effect for Au concentrations larger than those needed for in vivo photothermal treatments.Fil: Huergo, María Ana Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Giovanetti, Lisandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Rubert, Aldo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Grillo, Claudia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Moreno, Mario Sergio Jesus. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Requejo, Felix Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Salvarezza, Roberto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Vericat, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Cognitive Information Processing

Contains goals, background, research activities on one research project and reports on three research projects.Center for Advanced Television StudiesAmerican Broadcasting CompanyAmpex CorporationColumbia Broadcasting SystemsHarris CorporationHome Box OfficePublic Broadcasting ServiceNational Broadcasting CompanyRCA CorporationTektronix3M CompanyProvidence Gravure Co. (Grant)International Business Machines, Inc

Precursor or Product: The Blended Learning Environment in First Year Chemistry

AIMS Diverse learning platforms facilitate accessibility of content for non-traditional students and compensate for geographical limitations that universities might experience. In utilizing diverse learning platforms, it is critical to ensure effective and equitable teaching and learning outcomes across different student demographics. Based on the foundation and first year chemistry offerings at the University of New England (UNE), we aim to develop a theoretical construct for the basis of a long term quantitative study on student performance across multiple learning platforms. SOURCES OF EVIDENCE Pressure to speed up the evolution of blended learning in many courses comes from management, students, industry, and certain cohorts of academics. Students suggest all content and activities should be available online. Management emphasizes reaching a broader audience, and doing so economically. Industry wants novice and veteran chemists to revisit some fundamental concepts and lab skills. Educators want to embrace effective teaching strategies for every student population. It is well established in the education literature that “diverse student groups bring with them a rich prior experiences and knowledge about science as well as their own ways of knowing, thinking, and communicating that influences their learning” (Walls, 2016). In a recent review (Cooper, 2018), several studies were highlighted as reporting demographic disadvantages to online learning, and other research (DeKorver, 2016) also suggests demographics and student goals correlate with assessment outcomes; which demonstrates that not every iteration within the blended learning spectrum is equal. The learning platforms utilised to teach chemistry at UNE are diverse. Foundation and first-year chemistry content is presented in several combinations of the following: conventional lectures throughout the term, online lectures throughout the term, conventional laboratory experiments throughout the term, expedited laboratory experiments during one ‘intensive’ week, flipped classroom ‘workshops’ on campus, evening ‘tutorials’ on campus, and evening online ‘Q&A’ sessions. All students participate in a combination of the aforementioned learning platforms. Despite on-campus and online students being given the same content and assessments, student performance remains different. MAIN ARGUMENT Where do the learning platforms used in chemistry fit into the blended learning landscape? Are we currently a precursor or product of the blended learning format? We are at a pivotal point in education with the advent, flexibility, and economics of online study, and so we must re-evaluate the relative effectiveness of our learning platforms and our traditional methods to assess student learning, particularly in relation to diversity of learning platforms. As discussed, student demographics and individual learning goals are critical factors in performance; and if the design and range of learning platforms is satisfactory, they should be shown to support underperforming cohorts. CONCLUSIONS This work will elucidate the key components of first-year chemistry learning platforms and highlight any underrepresented student populations who will require the next step in evolution within blended learning. This information will be an important consideration in the design of future teaching and learning strategies. The results of this study will be applicable to other fields of science traditionally taught through a combination of lectures and activities in a laboratory (e.g., biology, physics) or field settings (e.g., ecology, geology, environmental sciences)

Replication Data for: Representation, Competing Principals, and Waffling on Bills in U.S. Legislatures

Legislators are often placed in the position of representing the interests of their constituents against the preferences of their own party leaders. We develop a theoretical framework indicating that these cross-pressured legislators are more likely to initially support legislation and subsequently change their minds than are legislators whose constituents and leaders share similar preferences. Moreover, we expect this pattern to be most pronounced among members of majority parties than minority party members. We test our expectations using data on bill cosponsorship and final passage votes from 46 lower state legislative chambers and the U.S. House, finding considerable support for our theory

Irreducible sign k-potent sign pattern matrices

The sign pattern matrix A is called sign k-potent if k is the smallest positive integer for which Ak+1=A. We characterize the irreducible pattern matrices that are sign k-potent and provide a canonical form for such matrices

Replication data for: Do Campaign Donors Influence Polarization? Evidence from Public Financing in the American States

Does the source of campaign funds influence legislative polarization? We develop competing theoretical expectations regarding the effects of publicly-financed elections on legislative voting behavior. To test these expectations, we leverage a natural experiment in the New Jersey Assembly in which public financing was made available to a subset of members. We find that public financing exerts substantively negligible effects on roll call voting. We then find a similar result in an examination of state legislatures. We conclude that, counter to the logic of the U.S. Supreme Court, pundits, and reformers, the source of campaign funds exerts minimal influence on polarization