Significant Structural Reorganization Research Articles

Dynamic reorganization of cortical structure in multi-domain regions after capsular and pontine stroke

Subcortical stroke may cause widespread structural changes to the cerebral cortex in multiple domains; however, the details of this process remain unclear. In this prospective observational study, we acquired two datasets to investigate the effect of lesion location on cortical structure. One was cross-sectional, comprising 269 patients with chronic stroke, either capsular stroke (CS) or pontine stroke (PS), and the other was longitudinal, comprising 119 patients with CS or PS. In the chronic-stage data, both CS and PS exhibited reduced cortical thickness in the precentral gyrus and increased cortical thickness and area in the frontal, temporal, occipital and insular cortices. Cortical thicknesses were correlated with motor outcomes in the precentral and lingual gyri, and early impairment of the corticospinal tract was associated with cortical thickness in the middle frontal gyrus. In the longitudinal dataset, CS showed gradually decreasing cortical thickness in the precentral gyrus, and both CS and PS showed gradually increasing cortical thickness and area in regions with significant structural reorganization. Subcortical stroke can therefore cause complex cortical structural changes in multi-domain regions involved in motor, primary and higher cognitive areas and have different evolution patterns depending on the subcortical level of the lesion affecting the motor pathways.

Consistent responses of coral microbiome to acute and chronic heat stress exposures

Frequent and intense heat waves lead to bleaching and even death of reef-building corals, and the thermal tolerance ultimately depends on the genetic composition of the holobiont. Here, we compared the effects of acute and chronic heat stress exposures on coral Porites cylindrica holobiont. Regardless of the temperature treatment, corals at 33 °C showed signs of bleaching and a significant decrease in photochemical efficiency (Fv/Fm). However, Symbiodiniaceae communities were relatively stable and all dominated by the same genus Cladocopium (C15). The relative abundanbce of core microbiome varied significantly, and they may provide several functions important to holobiont fitness. Both heat stress exposures induced the significant structural reorganization of coral-associated bacteria, with bacterial diversity and community heterogeneity significantly increasing with the temperature treatment. The modified stochasticity ratio (MST) revealed that stochastic processes dominated bacterial community assembly in thermally stressed corals. Certain core bacterial members that were hypothesized to fulfil functional niche decreased significantly, with the enrichment of potentially pathogenic and opportunistic bacteria in heat stress exposures. Thermally stressed corals had more positive correlation, higher network complexity and tighter associations among microbial taxa, relative to healthy corals. Overall, the coral microbiome exhibits similar responses to acute and chronic heat stress, and our study provides new insights about the deleterious impacts of complex warming oceans on coral holobiont.

Структурна трансформація протокової системи підшлункової залози у хворих на хронічний панкреатит

Актуальність. Клітини проток становлять до 30 % від маси підшлункової залози (ПЗ) людини, а збільшення кількості бранчів проток відноситься до одних із перших сонологічних ознак хронічного панкреатиту (ХП). Мета дослідження — визначення морфологічних й імуногістохімічних особливостей протокової системи ПЗ хворих на ХП, яким були виконані резекційні та дренуючі операції з приводу ускладнень хронічного панкреатиту. Матеріали та методи. Проведено імуногістохімічне дослідження операційного матеріалу 40 хворих з ускладненим хронічним панкреатитом з використанням реакцій на a-ізоформу гладком’язового актину (a-SMA), десмін, фібронектин й колаген I типу. Результати. Характерна морфологічна картина розвитку ХП є поєднанням фіброзування з деформацією протокової системи за рахунок перидуктального фіброзу з розширенням міждолькових фіброзних септ, потовщенням інтралобулярних сполучно­тканинних тяжів, а також значною звивістістю і розширенням проток з ретенційними кістами. Значна структурна перебудова протокової системи ПЗ у хворих на ХП спостерігалася в 87,5 % випадків, в 17,5 % випадків картина доповнювалася явищами ацинарно-протокової метаплазії з трансформацією ацинарних клітин у протокові і формуванням дрібних дуктулоподібних структур, так званих тубулярних комплексів. У 7,5 % випадків в головній панкреатичній протоці визначалися вогнища атрофії протокового епітелію, які чергувалися з вогнищами папілярної інтраепітеліальної гіперплазії епітелію (PanIN). Розвитку панкреатичного фіброзу при ХП сприяє накопичення a-SMA+-активованих панкреатичних зірчастих клітин, що синтезують надлишок компонентів екстрацелюлярного матриксу, зокрема колагену I типу. Середня площа колагену І типу та інтенсивність його експресії були вірогідно нижче при зниженій експресії a-SMA (p < 0,05) і вірогідно вище у випадках вираженої експресії фібронектину (p < 0,05). Висновки. Вивчення структурних змін протокової системи ПЗ з використанням методів імуногістохімії є одним із способів покращення ранньої діагностики ускладнень ХП.

Functional and structural brain connectivity in congenital deafness.

Several studies have been carried out to verify neural plasticity and the language process in deaf individuals. However, further investigations regarding the intrinsic brain organization on functional and structural neural networks derived from congenital deafness are still an open question. The objective of this study was to investigate the main differences in brain organization manifested in congenitally deaf individuals, concerning the resting-state functional patterns, and white matter structuring. Functional and diffusion magnetic resonance imaging modalities were acquired from 18 congenitally deaf individuals and 18 age-sex-matched hearing controls. Compared to the hearing group, the deaf individuals presented higher functional connectivity among the posterior cingulate cortex node of the default mode network with visual and motor networks, lower functional connectivity between salience networks, language networks, and prominence of functional connectivity changes in the right hemisphere, mostly in the frontoparietal and temporal lobes. In terms of structural connectivity, we found changes mainly in the occipital and parietal lobes, involving both classical sign language support regions as well as concentrated networks for focus activity, attention, and cognitive filtering. Our findings demonstrated that the congenital deaf individuals who learned sign language developed significant brain functional and structural reorganization, which provides prominent support for large-scale brain networks associated with attention decision-making, environmental monitoring based on the movement of objects, and on the motor and visual controls.

Characterization of immiscibility in calcium borosilicates used for the immobilization of Mo6+ under Au‐irradiation

AbstractThe aim of this paper was to assess factors affecting primary and secondary phase separation in simplified calcium borosilicate glasses studied for nuclear waste applications. Several glasses with varying [MoO3] and [B2O3] were synthesized and exposed to Au‐irradiation to examine compositional effects on glass structure and domain size of separated phases induced by accumulated radiation damage resulting from α‐decay over a ~1000 year timeframe. The produced glasses fell within the immiscibility dome of CaO−SiO2−B2O3 and showed a unique microstructure of embedded immiscibility with three identifiable amorphous phases according to electron microscopy, Raman spectroscopy, and diffraction. These glasses were then bombarded with 7 MeV Au3+ ions to a dose of 3 × 1014 ions/cm2 creating an estimated ~1 dpa of damage. Several changes to the morphology, spatial distribution, and size of secondary phases were observed, indicative of significant structural reorganization and changes to the chemical composition of each phase. A general mechanism of coalescence to form larger particles was observed for [MoO3] < 2.5 mol%, whereas segregation to form smaller more evenly distributed particles was seen for [B2O3] ≤ 15 mol% and [MoO3] ≥ 2.5 mol%. These microscopic changes were concurrent to surface‐bulk diffusion of Ca and/or Mo ions, where the direction of diffusion was dependent on [B2O3] with a barrier identified at ~20 mol%, as well as cross‐phase diffusion of said ions. These modifications occurred in part through the formation of distorted ring structures within the borosilicate network, which enabled the increased dissolution of isolated (MoO4)2− units. Au‐irradiation was therefore able to increase the solubility of molybdenum and alter the structure and composition of secondary phases with the extent of modification varying with [MoO3] and [B2O3]/[SiO2], though glasses notably remained heterogeneous. The collective results suggest that radiation and composition can both be used as design tools to modulate the domain size and distribution of separated phases in heterogeneous glasses.

A Nonlinear Optical Switchable Sulfate of Ultrawide Bandgap

Nonlinear optical (NLO) switchable materials have attracted intense attention because of their promising applications in optoelectronic devices. However, previous studies are mainly limited to mole...

Markov State Model of Lassa Virus Nucleoprotein Reveals Large Structural Changes during the Trimer to Monomer Transition

Lassa virus contains a nucleoprotein (NP) that encapsulates the viral genomic RNA forming the ribonucleoprotein (RNP). The NP forms trimers that do not bind RNA, but a structure of only the NP N-terminal domain was co-crystallized with RNA bound. These structures suggested a model in which the NP forms a trimer to keep the RNA gate closed, but then is triggered to undergo a change to a form competent for RNA binding. Here, we investigate the scenario in which the trimer is disrupted to observe whether monomeric NP undergoes significant conformational changes. From multi-microsecond molecular dynamics simulations and an adaptive sampling scheme to sample the conformational space, a Markov state model (MSM) is constructed. The MSM reveals an energetically favorable conformational change, with the most significant changes occurring at the domain interface. These results support a model in which significant structural reorganization of the NP is required for RNP formation.

Responses of soil microbial communities and their network interactions to saline-alkaline stress in Cd-contaminated soils

Land degradation by salinization and sodification changes soil function, destroys soil health, and promotes bioaccumulation of heavy metals in plants, but little is known about their fundamental mechanisms in shaping microbial communities and regulating microbial interactions. In this study, we explored the impact of saline-alkaline (SA) stress on soil bacterial and fungal community structures in different Cd-contaminated soils of Dezhou, Baoding, Xinxiang, Beijing and Shenyang cities from the North China Plain, China. Increased soil salinity and alkalinity enhanced Cd availability, indicated by significant increases in available Cd2+ in soil solution of 34.1%–49.7%, soil extractable Cd of 32.0–51.6% and wheat root Cd concentration of 24.5%–40.2%, as well as decreased activities of antioxidative enzymes of wheat root when compared with CK (no extra neutral or alkaline salts added). Soil bacteria were more active in response to the SA stress than fungi, as the significant structural reorganization of soil bacterial microbiota rather than fungal microbiota between SA and CK treatments was illustrated by principal component analysis. Adding neutral and alkaline salts enriched oligotrophic and haloalkaliphilic taxa in the Sphingobacteriaceae, Cellvibrionaceae, and Caulobacteraceae bacterial families, but decreased some Acidobacteria such as subgroup 6_norank, which was a sensitive biomarker that responded only to Cd contamination in CK-treated soils. Conversely, fungi were more sensitive to soil differences than bacteria: the composition of the fungal community was significantly different among different soil types. Phylogenetic molecular ecological network (pMEN) analysis further indicated that the microbial community structure and network interactions were altered to strengthen the adaptability of microorganisms to SA stress; the changes in structure and network interactions were proposed to contribute to competitive interactions. Most of the keystone genera identified in SA-treated soils, such as Blastococcus, Gemmatimonas, RB41, or Candida, had relatively low abundances (<1%), indicating their disproportionate ecological roles in triggering resistance or tolerance to SA stress and Cd toxicity.

Molecular Origins of the Apparent Ideal CO2 Solubilities in Binary Ionic Liquid Mixtures.

Molecular dynamics (MD) simulations were conducted to investigate the variation of Henry's constant of CO2 in two binary ionic liquid mixtures. One of the mixtures is formed by pairing the cation 1- n-butyl-3-methylimidazolium [C4mim]+ with chloride Cl- and methylsulfate [MeSO4]-, whereas the other binary ionic liquid mixture contains [C4mim]+ in combination with the anions Cl- and bis(trifluoromethanesulfonyl)imide [NTf2]-. In order to provide a microscopic understanding of the behavior of the Henry's constant with the anion composition, MD simulations of ionic liquid mixtures with and without CO2 saturation were performed at 353 K and 10 bar. Our calculations indicate that the Henry's constant for CO2 follows a highly nonlinear, although expected based on ideal solubility, trend with respect to the increasing concentration of Cl- in [C4mim]Cl x[NTf2]1- x, whereas the Henry's constant is almost independent of the anion composition in the [C4mim]Cl x[MeSO4]1- x system. Structural analyses presented in terms of radial, spatial, and angular distribution functions point to significant structural reorganization of the anions around cations in the [C4mim]Cl x[NTf2]1- x system. Because of the weakly coordinating ability of the [NTf2]- anion with the cation, the [NTf2]- anion is displaced from the equatorial plane of the imidazolium ring and occupies positions above and below the ring, enabling enhanced CO2-[NTf2]- association. The rearrangement also weakens the cation π-π interactions, resulting in the formation of increased local free volume aiding CO2 accommodation. On the contrary, such structural transitions are absent in the [C4mim]Cl x[MeSO4]1- x mixture system.

Strategic Planning and service provision in Greek Local government: a comparative assessment

This paper evaluates the impact of strategic planning on the performance of municipal services in Greece in lieu of the recent policy reforms. Improvement in public performance management has been the core tenet in the Greek Local Government Reform, now spanning over two decades. The recent “Kallikratis’’ reform program triggered significant structural re-organization across local government organizations in an attempt to address and resolve centralization and democratic deficit problems, but its impact on municipal services performance remained particularly limited Evidence confirmed marginal improvements in services efficiency and quality, but not substantial enough to inspire municipalities’ economic sustainability and citizens’ level of trust and satisfaction. Performance and governance deficits in municipal services provision, arising from the inherent restrictions of social capital in Greece, characterized by low rates of trust and collaboration, the Weberian characteristics of the hierarchal and centralized decision making in local government, the existence of multiple and overlapping levels and categories of audits and the failure to integrate innovative policy tools for better design and delivery of municipal services). These deficits reflected a lack of an effective national policy for the promotion of strategic management and performance measurement and the limited compliance of local government authorities with their tools and management models. Based on the combination qualitative and quantitative empirical data, this research thus, evaluates and analyzes the existence, perception, and impact of strategic management tools on municipal services performance, by focusing on 39 municipal authorities and 8 service sectors.

Molecular Dynamics Investigation of Halide-Containing Phospho-Silicate Bioactive Glasses.

Oxyhalide-containing silicate glasses have been receiving increasing attention in recent years due to their extensive medical and dental applications. This manuscript reports the first detailed structural investigation using MD simulations in the context of chloride- and mixed-fluoride/chloride-containing phospho-silicate bioactive glasses. It is shown that adding fluoride, chloride, and mixed fluoride and chloride has not altered the Q n silicate distribution and phosphorus speciation significantly in all of the glasses investigated. The Q2 silicon species is the predominant species with smaller and nearly equal proportions of Q1 and Q3 species, whereas phosphorus is largely present as orthophosphate Q0 units. No Si-F/Cl and P-F/Cl bonds have been observed at room temperature. Both F and Cl anions are present as F-Ca(n) and Cl-Ca(n). MD simulations also indicate opposite effects of fluoride and chloride on the crystallization ability of the glasses. The environment of Cl in chloride-containing glass series is quite different from the chlorapatite and CaCl2 crystals, and a significant structural reorganization is required to observe the appearance of the crystal nuclei. Instead, the environment of fluoride ions in the glasses is quite similar to that present in the FAP and CaF2 crystals and thus F-containing glasses manifest a high crystallization tendency. Moreover, in the mixed-fluoride/chloride-containing glasses, fluorine tends to surround phosphate, whereas chloride moves toward the silicate network. Finally, it was observed that a good correlation exists between the glass transition temperature and the overall strength of the glass network quantified by the Fnet factor.

Variable and low-toxic polyampholytes: complexation with biological membranes

In this paper, we describe three series of polyampholytes synthesized via quaternization of poly(4-vinylpyridin) by ω-bromocarboxylic acids and alkyl bromides: (1) with cationic and anionic groups in each unit (polybetaines), (2) with betaine and cationic groups, and (3) with betaine and pendant alkyl groups. The polymers were complexed with anionic mixed lipid membranes, liposomes, and Langmuir monolayers. By varying a length of –(CH2)n– spacer in the betaine group, different behaviors of polybetaines in a suspension of anionic liposomes can be realized: from no interaction to complexation followed by significant structural reorganization in the liposomal membrane. Cytotoxicities of polyampholytes are one to two orders of magnitude less than the cytotoxicity of a pure polycationic polymer with the same degree of polymerization. These results are of importance in designing polyelectrolytes with a higher affinity to the biolodical (cell) membrane and minimum cytotoxicity and demonstrate the potential of polyampholytes in developing biocompatible polymeric structures.

Do group I metabotropic glutamate receptors mediate LTD?

Synapses undergo significant structural and functional reorganization in response to varying patterns of stimulation. These forms of plasticity are considered fundamental to cognition and neuronal homeostasis. An increasing number of reports highlight the importance of activity-dependent synaptic strengthening (long term potentiation: LTP) for learning. However, the functional significance of activity-dependent weakening of synapses (long term depression: LTD) remains relatively poorly understood. One form of synaptic weakening, induced by group I metabotropic glutamate receptors (mGluRs), has received significant attention from a mechanistic point of view and because of its augmentation in a murine model of Fragile X Syndrome. Yet, studies of this form of plasticity often yield confusing, contradictory results. These conflicting findings are likely attributable to the bulk stimulation and recording techniques often used to study synaptic plasticity (typically involving evoked extracellular recordings, which represent the summed activity of many synapses). Such studies inherently blur the identity of the synapses undergoing change, thus giving the illusion that synapses per se are being modified when in fact this may only be true of a specific subset of synapses. Indeed, studies employing minimal synaptic activation paint a fundamentally different picture of what is commonly called “mGluR-LTD”. Here, I review the evidence in favour of group I mGluRs as mediators of various forms of synaptic downregulation and attempt to explain discrepancies in the literature. I argue that, while multiple forms of synaptic weakening may be triggered by these receptors, the canonical form of group I mGluR-mediated depression, mGluR-LTD, is in fact not a depression of basal synaptic responses. Rather, it is a reversal of established LTP and thus a form of depotentiation. Far from being arbitrary, this distinction has significant implications for the role of group I mGluRs in cognition, both in the healthy brain and in pathological conditions. Further, the differential actions of group I mGluRs at naïve and potentiated synapses suggest these receptors signal in a state-dependent manner to regulate various stages of the learning process.

Macro deformation and micro structure of 3D granular assemblies subjected to rotation of principal stress axes

This paper presents a numerical investigation on the behavior of three dimensional granular materials during continuous rotation of principal stress axes using the discrete element method. A dense specimen has been prepared as a representative element using the deposition method and subjected to stress rotation at different deviatoric stress levels. Significant plastic deformation has been observed despite that the principal stresses are kept constant. This contradicts the classical plasticity theory, but is in agreement with previous laboratory observations on sand and glass beads. Typical deformation characteristics, including volume contraction, deformation non-coaxiality, have been successfully reproduced. After a larger number of rotational cycles, the sample approaches the ultimate state with constant void ratio and follows a periodic strain path. The internal structure anisotropy has been quantified in terms of the contact-based fabric tensor. Rotation of principal stress axes densifies the packing, and leads to the increase in coordination numbers. A cyclic rotation in material anisotropy has been observed. The larger the stress ratio, the structure becomes more anisotropic. A larger fabric trajectory suggests more significant structure re-organization when rotating and explains the occurrence of more significant strain rate. The trajectory of the contact-normal based fabric is not centered in the origin, due to the anisotropy in particle orientation generated during sample generation which is persistent throughout the shearing process. The sample sheared at a lower intermediate principal stress ratio $$(b=0.0)$$ has been observed to approach a smaller strain trajectory as compared to the case $$b=0.5$$ , consistent with a smaller fabric trajectory and less significant structural re-organisation. It also experiences less volume contraction with the out-of plane strain component being dilative.

Critical role of intercalated water for electrocatalytically active nitrogen-doped graphitic systems.

Graphitic materials are essential in energy conversion and storage because of their excellent chemical and electrical properties. The strategy for obtaining functional graphitic materials involves graphite oxidation and subsequent dissolution in aqueous media, forming graphene-oxide nanosheets (GNs). Restacked GNs contain substantial intercalated water that can react with heteroatom dopants or the graphene lattice during reduction. We demonstrate that removal of intercalated water using simple solvent treatments causes significant structural reorganization, substantially affecting the oxygen reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Amid contrasting reports describing the ORR activity of GN-based catalysts in alkaline electrolytes, we demonstrate superior activity in an acidic electrolyte with an onset potential of ~0.9 V, a half-wave potential (E ½) of 0.71 V, and a selectivity for four-electron reduction of >95%. Further, durability testing showed E ½ retention >95% in N2- and O2-saturated solutions after 2000 cycles, demonstrating the highest ORR activity and stability reported to date for GN-based electrocatalysts in acidic media.

Application of the F-Response for Estimating Motor Unit Number and Amplitude Distribution in Hand Muscles of Stroke Survivors.

The F-response was used in this study to assess changes in the first dorsal interosseous (FDI) muscle after a hemispheric stroke. The number of motor units and their sizes were estimated bilaterally in 12 stroke survivors by recording both the compound muscle action potential (CMAP) and F wave responses. These F waves were induced by applying a large number of electrical stimuli to the ulnar nerve. The amplitude distribution of individual motor unit action potentials (MUAPs) was also compared between paretic and contralateral muscles. When averaged across all the subjects, a significantly lower motor unit number estimate was obtained for the paretic FDI muscle ( 88 ±13) compared with the contralateral side ( 139 ±11) ( ). Pooled surface MUAP amplitude analysis demonstrated a right-skewed distribution for both paretic (kurtosis 3.0) and contralateral (kurtosis 8.52) muscles. When normalized to each individual muscle's CMAP, the surface MUAP amplitude ranged from 0.22% to 4.94% (median 1.17%) of CMAP amplitude for the paretic muscle, and from 0.13% to 3.2% (median 0.62%) of CMAP amplitude for the contralateral muscle. A significant difference in MUAP outliers was also observed between the paretic and contralateral muscles. The findings of this study suggest significant motor unit loss and muscle structural reorganization after stroke.

Mechanistic studies of hydrogen evolution in aqueous solution catalyzed by a tertpyridine-amine cobalt complex.

The ability of cobalt-based transition metal complexes to catalyze electrochemical proton reduction to produce molecular hydrogen has resulted in a large number of mechanistic studies involving various cobalt complexes. While the basic mechanism of proton reduction promoted by cobalt species is well-understood, the reactivity of certain reaction intermediates, such as Co(I) and Co(III)-H, is still relatively unknown owing to their transient nature, especially in aqueous media. In this work we investigate the properties of intermediates produced during catalytic proton reduction in aqueous solutions promoted by the [(DPA-Bpy)Co(OH2)](n+) (DPA-Bpy = N,N-bis(2-pyridinylmethyl)-2,20-bipyridine-6-methanamine) complex ([Co(L)(OH2)](n+) where L is the pentadentate DPA-Bpy ligand or [Co(OH2)](n+) as a shorthand). Experimental results based on transient pulse radiolysis and laser flash photolysis methods, together with electrochemical studies and supported by density functional theory (DFT) calculations indicate that, while the water ligand is strongly coordinated to the metal center in the oxidation state 3+, one-electron reduction of the complex to form a Co(II) species results in weakening the Co-O bond. The further reduction to a Co(I) species leads to the loss of the aqua ligand and the formation of [Co(I)-VS)](+) (VS = vacant site). Interestingly, DFT calculations also predict the existence of a [Co(I)(κ(4)-L)(OH2)](+) species at least transiently, and its formation is consistent with the experimental Pourbaix diagram. Both electrochemical and kinetics results indicate that the Co(I) species must undergo some structural change prior to accepting the proton, and this transformation represents the rate-determining step (RDS) in the overall formation of [Co(III)-H](2+). We propose that this RDS may originate from the slow removal of a solvent ligand in the intermediate [Co(I)(κ(4)-L)(OH2)](+) in addition to the significant structural reorganization of the metal complex and surrounding solvent resulting in a high free energy of activation.

AlPO4-54–AlPO4-8 Structural Phase Transition and Amorphization under High Pressure

Microporous AlPO4-54, which exhibits the largest pores among zeolites and aluminophosphates with a diameter of 12.7 A, was investigated at high pressure by X-ray powder diffraction (XRD), mid- and far-infrared (IR) spectroscopy in diamond anvil cells. The material undergoes a phase transition beginning around 0.8 GPa. The amount of AlPO4-8 gradually increases with pressure and the phase transition is complete between 2 and 3 GPa. The closure of the (P—O—Al) angle destabilizes the structure of AlPO4-54, which drives the transition to AlPO4-8. The pressure-induced phase transformation of AlPO4-54 to AlPO4-8 is associated with a symmetry reduction from hexagonal to orthorhombic and with a change in the unidirectional ring channel parallel to the c-axes from 18 to 14 AlO4 and PO4 tetrahedra. An abrupt decrease along the b direction is linked to the formation of 4 new rings of 6 tetrahedra with significant structural reorganization. The transition is followed by irreversible amorphization beginning around 3.5 ...

Reorganizing for Transformational Change: The 21st Century Research Library at a Flagship Public University

Beginning in November 2010 and culminating in February 2012, the University of Colorado Boulder Libraries began planning a significant structural reorganization. Local, pragmatic drivers for the change included retirements at the executive level and the loss of professional librarian lines due to the Great Recession of 2008. But other, more important catalysts existed and are driving similar reorganization efforts in research libraries across the country. The increasingly interdisciplinary, digital, and inter-institutional nature of scholarship, research and teaching requires a more flexible, team-managed research library. Dramatic shifts in how institutions of higher education are funded are also fueling the need to reevaluate organizational structures. This article will explore the process, strategy, and on-going efforts to recreate the research library at the University of Colorado Boulder.

Interface controlled oxidation states in layered cobalt oxide nanoislands on gold.

Layered cobalt oxides have been shown to be highly active catalysts for the oxygen evolution reaction (OER; half of the catalytic "water splitting" reaction), particularly when promoted with gold. However, the surface chemistry of cobalt oxides and in particular the nature of the synergistic effect of gold contact are only understood on a rudimentary level, which at present prevents further exploration. We have synthesized a model system of flat, layered cobalt oxide nanoislands supported on a single crystal gold (111) substrate. By using a combination of atom-resolved scanning tunneling microscopy, X-ray photoelectron and absorption spectroscopies and density functional theory calculations, we provide a detailed analysis of the relationship between the atomic-scale structure of the nanoislands, Co oxidation states and substrate induced charge transfer effects in response to the synthesis oxygen pressure. We reveal that conversion from Co(2+) to Co(3+) can occur by a facile incorporation of oxygen at the interface between the nanoisland and gold, changing the islands from a Co-O bilayer to an O-Co-O trilayer. The O-Co-O trilayer islands have the structure of a single layer of β-CoOOH, proposed to be the active phase for the OER, making this system a valuable model in understanding of the active sites for OER. The Co oxides adopt related island morphologies without significant structural reorganization, and our results directly demonstrate that nanosized Co oxide islands have a much higher structural flexibility than could be predicted from bulk properties. Furthermore, it is clear that the gold/nanoparticle interface has a profound effect on the structure of the nanoislands, suggesting a possible promotion mechanism.