Updated Review of Radiologic Imaging and Intervention for Acute Pancreatitis and Its Complications.

This is a current update on radiologic imaging and intervention of acute pancreatitis and its complications. In this review, we define the various complications of acute pancreatitis, discuss the imaging findings, as well as the timing of when these complications occur. The various classification and scoring systems of acute pancreatitis are summarized. Advantages and disadvantages of the 3 primary radiologic imaging modalities are compared. We then discuss radiologic interventions for acute pancreatitis. These include diagnostic aspiration as well as percutaneous catheter drainage of fluid collections, abscesses, pseudocysts, and necrosis. Recommendations for when these interventions should be considered, as well as situations in which they are contraindicated are discussed. Fortunately, acute pancreatitis usually is mild; however, serious complications occur in 20%, and admission of patients to the intensive care unit (ICU) occurs in over 10%. In this paper, we will focus on the imaging and interventional radiologic aspects for the serious complications and patients admitted to the ICU.

Atlantic meridional overturning circulation increases flood risk along the United States southeast coast.

The system of oceanic flows constituting the Atlantic Meridional Overturning Circulation (AMOC) moves heat and other properties to the subpolar North Atlantic, controlling regional climate, weather, sea levels, and ecosystems. Climate models suggest a potential AMOC slowdown towards the end of this century due to anthropogenic forcing, accelerating coastal sea level rise along the western boundary and dramatically increasing flood risk. While direct observations of the AMOC are still too short to infer long-term trends, we show here that the AMOC-induced changes in gyre-scale heat content, superimposed on the global mean sea level rise, are already influencing the frequency of floods along the United States southeastern seaboard. We find that ocean heat convergence, being the primary driver for interannual sea level changes in the subtropical North Atlantic, has led to an exceptional gyre-scale warming and associated dynamic sea level rise since 2010, accounting for 30-50% of flood days in 2015-2020.

The International Bathymetric Chart of the Arctic Ocean Version 4.0.

Bathymetry (seafloor depth), is a critical parameter providing the geospatial context for a multitude of marine scientific studies. Since 1997, the International Bathymetric Chart of the Arctic Ocean (IBCAO) has been the authoritative source of bathymetry for the Arctic Ocean. IBCAO has merged its efforts with the Nippon Foundation-GEBCO-Seabed 2030 Project, with the goal of mapping all of the oceans by 2030. Here we present the latest version (IBCAO Ver. 4.0), with more than twice the resolution (200 × 200 m versus 500 × 500 m) and with individual depth soundings constraining three times more area of the Arctic Ocean (∼19.8% versus 6.7%), than the previous IBCAO Ver. 3.0 released in 2012. Modern multibeam bathymetry comprises ∼14.3% in Ver. 4.0 compared to ∼5.4% in Ver. 3.0. Thus, the new IBCAO Ver. 4.0 has substantially more seafloor morphological information that offers new insights into a range of submarine features and processes; for example, the improved portrayal of Greenland fjords better serves predictive modelling of the fate of the Greenland Ice Sheet.

Validation of Glacier Topographic Acquisitions from an Airborne Single-Pass Interferometer.

The airborne glacier and ice surface topography interferometer (GLISTIN-A) is a single-pass radar interferometer developed for accurate high-resolution swath mapping of dynamic ice surfaces. We present the first validation results of the operational sensor, collected in 2013 over glaciers in Alaska and followed by more exhaustive collections from Greenland in 2016 and 2017. In Alaska, overlapping flight-tracks were mosaicked to mitigate potential residual trends across-track and the resultant maps are validated with lidar. Furthermore, repeat acquisitions of Columbia Glacier collected with a three day separation indicate excellent stability and repeatability. Commencing 2016, GLISTIN-A has circumnavigated Greenland for 4 consecutive years. Due to flight hour limitations, overlapping swaths were not flown. In 2016, comparison with airborne lidar data finds that residual systematic errors exhibit evenly distributed small slopes (all less than 10 millidegrees) and nadir biases were typically less than 1 m. Similarly 2017 data exhibited up to meter-scale nadir biases and evenly distributed residual slopes with a standard deviation of ~10 millidegrees). All satisfied the science accuracy requirements of the Greenland campaigns (3 m accuracy across an 8 km swath).

In Situ X-ray Scattering Guides the Synthesis of Uniform PtSn Nanocrystals.

Compared to monometallic nanocrystals (NCs), bimetallic ones often exhibit superior properties due to their wide tunability in structure and composition. A detailed understanding of their synthesis at the atomic scale provides crucial knowledge for their rational design. Here, exploring the Pt-Sn bimetallic system as an example, we study in detail the synthesis of PtSn NCs using in situ synchrotron X-ray scattering. We show that when Pt(II) and Sn(IV) precursors are used, in contrast to a typical simultaneous reduction mechanism, the PtSn NCs are formed through an initial reduction of Pt(II) to form Pt NCs, followed by the chemical transformation from Pt to PtSn. The kinetics derived from the in situ measurements shows fast diffusion of Sn into the Pt lattice accompanied by reordering of these atoms into intermetallic PtSn structure within 300 s at the reaction temperature (∼280 °C). This crucial mechanistic understanding enables the synthesis of well-defined PtSn NCs with controlled structure and composition via a seed-mediated approach. This type of in situ characterization can be extended to other multicomponent nanostructures to advance their rational synthesis for practical applications.

Corrigendum: High-temperature crystallization of nanocrystals into three-dimensional superlattices.

This corrects the article DOI: 10.1038/nature23308.

Systematic Identification of Promoters for Methane Oxidation Catalysts Using Size- and Composition-Controlled Pd-Based Bimetallic Nanocrystals.

Promoters enhance the performance of catalytic active phases by increasing rates, stability, and/or selectivity. The process of identifying promoters is in most cases empirical and relies on testing a broad range of catalysts prepared with the random deposition of active and promoter phases, typically with no fine control over their localization. This issue is particularly relevant in supported bimetallic systems, where two metals are codeposited onto high-surface area materials. We here report the use of colloidal bimetallic nanocrystals to produce catalysts where the active and promoter phases are colocalized to a fine extent. This strategy enables a systematic approach to study the promotional effects of several transition metals on palladium catalysts for methane oxidation. In order to achieve these goals, we demonstrate a single synthetic protocol to obtain uniform palladium-based bimetallic nanocrystals (PdM, M = V, Mn, Fe, Co, Ni, Zn, Sn, and potentially extendable to other metal combinations) with a wide variety of compositions and sizes based on high-temperature thermal decomposition of readily available precursors. Once the nanocrystals are supported onto oxide materials, thermal treatments in air cause segregation of the base metal oxide phase in close proximity to the Pd phase. We demonstrate that some metals (Fe, Co, and Sn) inhibit the sintering of the active Pd metal phase, while others (Ni and Zn) increase its intrinsic activity compared to a monometallic Pd catalyst. This procedure can be generalized to systematically investigate the promotional effects of metal and metal oxide phases for a variety of active metal-promoter combinations and catalytic reactions.

High-temperature crystallization of nanocrystals into three-dimensional superlattices.

Crystallization of colloidal nanocrystals into superlattices represents a practical bottom-up process with which to create ordered metamaterials with emergent functionalities. With precise control over the size, shape and composition of individual nanocrystals, various single- and multi-component nanocrystal superlattices have been produced, the lattice structures and chemical compositions of which can be accurately engineered. Nanocrystal superlattices are typically prepared by carefully controlling the assembly process through solvent evaporation or destabilization or through DNA-guided crystallization. Slow solvent evaporation or cooling of nanocrystal solutions (over hours or days) is the key element for successful crystallization processes. Here we report the rapid growth (seconds) of micrometre-sized, face-centred-cubic, three-dimensional nanocrystal superlattices during colloidal synthesis at high temperatures (more than 230 degrees Celsius). Using in situ small-angle X-ray scattering, we observe continuous growth of individual nanocrystals within the lattices, which results in simultaneous lattice expansion and fine nanocrystal size control due to the superlattice templates. Thermodynamic models demonstrate that balanced attractive and repulsive interparticle interactions dictated by the ligand coverage on nanocrystal surfaces and nanocrystal core size are responsible for the crystallization process. The interparticle interactions can also be controlled to form different superlattice structures, such as hexagonal close-packed lattices. The rational assembly of various nanocrystal systems into novel materials is thus facilitated for both fundamental research and for practical applications in the fields of magnetics, electronics and catalysis.

Dynamical Observation and Detailed Description of Catalysts under Strong Metal-Support Interaction.

Understanding the structures of catalysts under realistic conditions with atomic precision is crucial to design better materials for challenging transformations. Under reducing conditions, certain reducible supports migrate onto supported metallic particles and create strong metal-support states that drastically change the reactivity of the systems. The details of this process are still unclear and preclude its thorough exploitation. Here, we report an atomic description of a palladium/titania (Pd/TiO2) system by combining state-of-the-art in situ transmission electron microscopy and density functional theory (DFT) calculations with structurally defined materials, in which we visualize the formation of the overlayers at the atomic scale under atmospheric pressure and high temperature. We show that an amorphous reduced titania layer is formed at low temperatures, and that crystallization of the layer into either mono- or bilayer structures is dictated by the reaction environment and predicted by theory. Furthermore, it occurs in combination with a dramatic reshaping of the metallic surface facets.

Influence of gender on long-term mortality in patients presenting with non-ST-elevation acute coronary syndromes undergoing percutaneous coronary intervention.

Although an invasive strategy has predominately been studied in men with non-ST-segment elevation acute coronary syndromes (NSTE-ACSs), its role in low-risk women is unclear. We sought to examine gender differences in a real-world registry of patients with NSTE-ACS who underwent percutaneous coronary intervention (PCI). Patients with NSTE-ACS undergoing PCI at the Cleveland Clinic, Cleveland, Ohio from 2003 through 2007 (n = 1,874) were included. In-hospital and long-term mortalities were assessed. Cox proportional hazards models were constructed to study the influence of gender on mortality. Interactions with age and biomarker status were examined. Women were older and had a higher incidence of co-morbid conditions compared to men. They had a smaller reference vessel diameter compared to men. Despite these characteristics there was no overall difference in in-hospital (1.4% vs 1.6%) or long-term (14.6% vs 15.8%) mortality between men and women. However, there was evidence of a significant effect modification by age (p = 0.012) and troponin status (p = 0.0073) for long-term mortality such that women <60 years of age, especially those who were troponin negative, had more than a twofold increase in long-term mortality compared to men (p = 0.007). In conclusion, although overall mortality rates are similar between men and women undergoing PCI for NSTE-ACS, women <60 years old with negative biomarkers have a higher mortality than their men peers.

Fold catastrophes and the dependence of free-energy barriers to conformational transitions on applied force.

Applied mechanical force (f) can activate conformational change in molecules by reducing the height of a free-energy barrier (DeltaG(b)). In this paper, molecular dynamics simulations are carried out with umbrella sampling and self-consistent histogram methods to determine free-energy profiles for a coarse-grained model of a protein under an applied force. Applied force is shown to cause fold catastrophes, where free-energy minima are destabilized until they disappear. It is well-known that a fold catastrophe at force f = B implies the scaling DeltaG(b) approximately |B - f|(3/2) in the limit of DeltaG(b) --> 0, but it is not clear whether this scaling is accurate for physically relevant barrier heights. The simulation results show that the fold catastrophe scaling is in fact accurate in the physically relevant regime and that the two-parameter function DeltaG(b) = A(B - f)(3/2) is superior to the two-parameter linear function for parametrizing changes in free-energy barriers with applied force.