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Crystal Toolkit is an open source tool for viewing, analyzing and transforming crystal structures, molecules and other common forms of materials science data in an interactive way. It is intended to help beginners rapidly develop web-based apps to explore their own data or to help developers make their research algorithms accessible to a broader audience of scientists who might not have any training in computer programming and who would benefit from graphical interfaces. Crystal Toolkit comes with a library of ready-made components that can be assembled to make complex web apps: simulation of powder and single crystalline diffraction patterns, convex hull phase diagrams, Pourbaix diagrams, electronic band structures, analysis of local chemical environments and symmetry, and more. Crystal Toolkit is now powering the Materials Project website frontend, providing user-friendly access to its database of computed materials properties. In the future, it is hoped that new visualizations might be prototyped using Crystal Toolkit to help explore new forms of data being generated by the materials science community, and that this in turn can help new materials scientists develop intuition for how their data behaves and the insights that might be found within. Crystal Toolkit will remain a work-in-progress and is open to contributions from the community.

GMP-Featurizer is a lightweight, accurate, efficient, and scalable software package for calculating the Gaussian Multipole (GMP) features \cite{GMP} for a variety of atomic systems with elements across the periodic table. Starting from the GMP feature computation module from AmpTorch \cite{amptorch}, the capability of GMP-Featurizer has since been greatly improved, including its accuracy and efficiency, as well as the ability to parallelize on different cores, even machines. Moreover, this python package only has very few dependencies that are all standard python libraries, plus cffi for C++ code interfacing and Ray \cite{Ray} for parallelization, making it lightweight and robust. A set of unit tests are designed to ensure the reliability of its outputs. A set of extensive examples and tutorials, as well as two sets of pseudopotential files (needed for specifying the GMP feature set), are also included in this package for its users. Overall, this package is designed to serve as a standard implementation for chemical and material scientists who are interested in developing models based on GMP features. The source code for this package is freely available to the public under the Apache 2.0 license.

As a large cocoa bean trader, Transmar group ltd. bought millions of dollars’ worth of beans relying on financing from a syndicate of banks. To monitor amounts of eligible collateral, the banks required Transmar prepare periodic borrowing base (BB) reports. At some point, Transmar developed a discrepancy in collateral recorded on the BB report versus the amount of funds borrowed. The case discusses how this discrepancy grew larger as many questionable and fraudulent entries were included on subsequent BB reports. The case is written from the perspective of Peter B. Johnson, head of Transmar’s European affiliate and son of CEO and founder of Transmar, Peter G. Johnson. In late 2014, Peter B. Johnson first learned about the deceptive practices being employed in preparing the BB reports. How will he react? The case is also rich in details surrounding the cocoa industry supply chain and history of cocoa production.

The purpose of this paper is to examine the economic benefits of community gardens and incubator farms, both of which support the populations they serve from an economic viewpoint as well as socially, and as a benefit to public health and nutrition. The findings were gathered from the large body of research concerning the benefits of community gardens as well as program evaluation responses conducted with gardeners at the Cache Refugee and Immigrant Connection (CRIC) garden in Logan, Utah in 2020. They are also informed by experiences had and lessons learned while working as the garden manager. There is a wealth of information being circulated by researchers in the field about how the many ways community gardens help members of a community, especially those who are considered disadvantaged groups such as increased feelings of wellbeing associated with being outside in green spaces and an increase in the amount of nutritious foods consumed by those who participate in community gardens. This wealth of information is most likely only rivaled by the abundance of food produced at the CRIC garden, which is consumed by those who grow it and their families and is also freely given in gratitude for the opportunities presented to them. It is true that many people come together to gather the resources that are needed to make the garden possible. Without grant money and donations of time and capital the garden would not be possible. But when looked at through the lens of what it gives back, the amount of wealth spread around is hard to fully understand. The purpose of this paper is to look at the benefits to those who are involved with a specific community garden in Logan, Utah. The total value of this garden in terms of saving and contributions to users and the surrounding community has been established. These findings seek to quantify and qualify the full extent of the impacts the garden has on the gardeners and the community as a whole.

Hydrogen peroxide is a valuable chemical oxidant with a wide range of applications in a variety of industrial processes, especially in water sanitization. Electrochemical synthesis of hydrogen peroxide (H2O2) through a two-electron oxygen reduction reaction (2e-ORR) or a two-electron water oxidation reaction (2e-WOR) has emerged as an appealing process for onsite production of this chemically valuable oxidant. On-site produced H2O2 can be applied for wastewater treatment in remote locations or any applications where H2O2 is needed as an oxidizing agent. This Review studies the theoretical efforts in understanding the challenges in catalysis for electrochemical synthesis of H2O2 as well as providing design principles for more efficient catalyst materials.

Discovering the ideal material for a new application involves determining its numerous properties, such as electronic, mechanical, or thermodynamic, to match those of its desired application. The rise of high-throughput computation has meant that large databases of material properties are now accessible to scientists. However, these databases contain far more information than might appear at first glance, since many relationships exist in the materials science literature to derive, or at least approximate, additional properties. propnet is a new computational framework designed to help scientists to automatically calculate additional information from their datasets. It does this by constructing a network graph of relationships between different materials properties and traversing this graph. Initially, propnet contains a catalog of over 100 property relationships but the hope is for this to expand significantly in the future, and contributions from the community are welcomed.

Electrocatalysis of the oxygen evolution reaction is central to several energy technologies including electrolyzers, solar fuel generators, and air-breathing batteries. Strong acid electrolytes are desirable for many implementations of these technologies, although the deployment of such device designs is often hampered by the lack of non-precious-metal oxygen evolution electrocatalysts, with Ir-based oxides comprising the only known catalysts that exhibit stable activity at low overpotential. During our exploration of the Mn-Sb-O system for precious-metal-free electrocatalysts, we discovered that Mn can be incorporated into the rutile oxide structure at much higher concentrations than previously known, and that these Mn-rich rutile alloys exhibit great catalytic activity with current densities exceeding 50 mA cm-2 at 0.58 V overpotential and catalysis onset at 0.3 V overpotential. While this activity does not surpass that of IrO2, Pourbaix analysis reveals that the Mn-Sb rutile oxide alloys have the same or better thermodynamic stability under operational conditions. By combining combinatorial composition, structure, and activity mapping with synchrotron X-ray absorption measurements and first-principles materials chemistry calculations, we provide a comprehensive understanding of these oxide alloys and identify the critical role of Sb in stabilizing the trivalent Mn octahedra that have been shown to be effective oxygen evolution reaction (OER) catalysts.

The Materials Project (MP) has served as an effec- tive dissemination platform for computational materials science data for nearly 8 years. In its capacity as a Science Gateway, it serves over 50,000 users from around the world with data on over 70,000 crystalline materials. In recent years, MP’s growing popularity has been facilitated by educational resources devel- oped by its core team and diligently maintained documentation of the methodology and provenance associated with its data. In this report, we highlight a recent effort by MP to standardize a set of educational materials for its user base in its annualMaterials Project Workshop, which was conducted in the summers of 2016 and 2017 and will be hosted again in August, 2018. More specifically, we describe our insights on how organization of material, presentation format, formative assessment, and active learning were integrated to produce an effective educational experience for our attendees. We also highlight the lessons we’ve learned, in the hopes other Science Gateway efforts may draw on our experiences in crafting their own educational and training resources.

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. While the search for catalysts capable of directly converting methane to higher value commodity chemicals and liquid fuels has been active for over a century, a viable industrial process for selective methane activation has yet to be developed. Electronic structure calculations are playing an increasingly relevant role in this search, but large-scale materials screening efforts are hindered by computationally expensive transition state barrier calculations. The purpose of the present letter is twofold. First, we show that, for the wide range of catalysts that proceed via a radical intermediate, a unifying framework for predicting C-H activation barriers using a single universal descriptor can be established. Second, we combine this scaling approach with a thermodynamic analysis of active site formation to provide a map of methane activation rates. Our model successfully rationalizes the available empirical data and lays the foundation for future catalyst design strategies that transcend different catalyst classes.

Databases of crystalline compounds typically have core properties such as relaxed structure, energy of formation, etc. pre-computed and available to users. However, additional material properties such as full elastic tensor, band structure, etc. may be both not of interest to all users of the database and computationally expensive to determine. Furthermore, researchers interested in such properties may only be interested in their values for specific compounds or chemistries. To crowdsource prioritization of optional-property calculations, we built an interactive leaderboard that serves as a gateway to our cyberinfrastructure (CI) for queuing jobs and dynamically reassigning job priorities. Users browse an ordered list of queued jobs, filter by chemistry for materials that are missing the property of interest, vote on existing or new jobs, and receive email notification when voted-on material properties are online. Here we will detail the use case of full elastic tensor calculations for the Materials Project, though the leaderboard interface can be run as a standalone web service and customized for contexts other than computational materials science.

We present a new nitrogen isotope model incorporated into the three-dimensional ocean component of a global Earth system climate model designed for millennial timescale simulations. The model includes prognostic tracers for the two stable nitrogen isotopes, 14N and 15N, in the nitrate (NO3−), phytoplankton, zooplankton, and detritus variables of the marine ecosystem model. The isotope effects of algal NO3− uptake, nitrogen fixation, water column denitrification, and zooplankton excretion are considered as well as the removal of NO3− by sedimentary denitrification. A global database of δ15NO3− observations is compiled from previous studies and compared to the model results on a regional basis where sufficient observations exist. The model is able to qualitatively and quantitatively reproduce many of the observed patterns such as high subsurface values in water column denitrification zones and the meridional and vertical gradients in the Southern Ocean. The observed pronounced subsurface minimum in the Atlantic is underestimated by the model presumably owing to too little simulated nitrogen fixation there. Sensitivity experiments reveal that algal NO3− uptake, nitrogen fixation, and water column denitrification have the strongest effects on the simulated distribution of nitrogen isotopes, whereas the effect from zooplankton excretion is weaker. Both water column and sedimentary denitrification also have important indirect effects on the nitrogen isotope distribution by reducing the fixed nitrogen inventory, which creates an ecological niche for nitrogen fixers and, thus, stimulates additional N2 fixation in the model. Important model deficiencies are identified, and strategies for future improvement and possibilities for model application are outlined.

The broad distribution and often high densities of the cyanobacterium Trichodesmium spp. in oligotrophic waters imply a substantial role for this one taxon in the oceanic N cycle of the marine tropics and subtropics. New results from 154 stations on six research cruises in the North Atlantic Ocean show depth-integrated N2 fixation by Trichodesmium spp. at many stations that equalled or exceeded the estimated vertical flux of NO3− into the euphotic zone by diapycnal mixing. Areal rates are consistent with those derived from several indirect geochemical analyses. Direct measurements of N2 fixation rates by Trichodesmium are also congruent with upper water column N budgets derived from parallel determinations of stable isotope distributions, clearly showing that N2 fixation by Trichodesmium is a major source of new nitrogen in the tropical North Atlantic. We project a conservative estimate of the annual input of new N into the tropical North Atlantic of at least 1.6 × 1012 mol N by Trichodesmium N2 fixation alone. This input can account for a substantial fraction of the N2 fixation in the North Atlantic inferred by several of the geochemical approaches.

We encountered an extensive bloom of the colonial diatom Hemiaulus hauckii along a 2500 km cruise track off the NE coast of South America in autumn 1996. Each diatom cell contained the heterocystous. N₂-fixing cyanobacterial endosymbiont Richeiia intracellularis. Surface Richeiia heterocyst (and filament) densities increased from 10⁶ heterocyst 1⁻¹ in the bloom. Total abundance ranged from 10⁶ eterocyst m⁻² outside the bloom to over 10¹⁰ heterocyst m⁻² within the bloom. Rates of primary production averaged 1.2 g C m⁻² d⁻¹, higher than typical for oligotrophic Open ocean waters. N₂ fixation during the bloom by the Richelia/Hemiaulus association added an average of 45 mg N m⁻² d⁻¹ to the water column. The relative importance of NH₄⁺ uptake over the Course of the bloom increased from 0 to 42% of total N uptake by the Hemiauluslficheiia association. N₂ fixation by Richelia exceeded estimates of 'new' N flux via NO₃ diffusion from deep water and, together with additional N, fixation by the cyanobacterium Trichodesmium, could supply about 25% of the total N demand through the water column during the bloom. Suspended particles and zooplankton collected within the bloom were depleted in ¹⁵N, reflecting the dominant contribution of N₂ fixation to the planktonic N budget. The bloom was spatially extensive, as revealed by satellite imagery, and is calculated to have contributed about 0.5 Tg N to the euphotic zone. Such blooms may represent an important and previously unrecognized source of new N to support primary production in nutrient-poor tropical waters. Furthermore, this bloom demonstrates that heterocystous cyanobacteria can also make quantitatively important contributions of N in oceanic water column environments.

We encountered an extensive surface bloom of the N, fixing cyanobactenum Trichodesrniurn erythraeum in the central basin of the Arabian Sea during the spring inter-monsooon of 1995. The bloom, which occurred dunng a period of calm winds and relatively high atmospheric iron content, was metabollcally active. Carbon fixation by the bloom represented about one-quarter of water column primary productivity while input by N₂ flxation could account for a major fraction of the estimated 'new' N demand of primary production. Isotopic measurements of the N in surface suspended material confirmed a direct contribution of N₂ fixation to the organic nltrogen pools of the upper water column. Retrospective analysis of NOAA-12 AVHRR imagery indicated that blooms covered up to 2 X 10⁶ km², or 20% of the Arabian Sea surface, during the period from 22 to 27 May 1995. In addition to their biogeochemical impact, surface blooms of this extent may have secondary effects on sea surface albedo and light penetration as well as heat and gas exchange across the air-sea interface. A preliminary extrapolation based on our observed, non-bloom rates of N₂ fixation from our limited sampling in the spring intermonsoon including a conservative estimate of the input by blooms, suggest N₂ fixation may account for an input of about 1 Tg N yr⁻¹. This is substantial, but relatively minor compared to current estimates of the removal of N through denitrification in the basin. However, N₂ fixation may also occur in the central basin through the mild winter monsoon, be considerably greater during the fall intermonsoon than we observed during the spring intermonsoon, and may also occur at higher levels in the chronically oligotrophic southern basin. Ongoing satellite observations will help to determine more accurately the distribution and density of Trichodesmium in this and other tropical oceanic basins, as well as resolving the actual frequency and duration of bloom occurrence.

The Amazon River has the largest discharge of all rivers on Earth, and its complex plume system fuels a wide array of biogeochemical processes, across a large area of the western tropical North Atlantic. The plume thus stimulates microbial processes affecting carbon sequestration and nutrient cycles at a global scale. Chromosomal gene expression patterns of the 2.0 to 156 μm size-fraction eukaryotic microbial community were investigated in the Amazon River Plume, generating a robust dataset (more than 100 million mRNA sequences) that depicts the metabolic capabilities and interactions among the eukaryotic microbes. Combining classical oceanographic field measurements with metatranscriptomics yielded characterization of the hydrographic conditions simultaneous with a quantification of transcriptional activity and identity of the community. We highlight the patterns of eukaryotic gene expression for 31 biogeochemically significant gene targets hypothesized to be valuable within forecasting models. An advantage to this targeted approach is that the database of reference sequences used to identify the target genes was selectively constructed and highly curated optimizing taxonomic coverage, throughput, and the accuracy of annotations. A coastal diatom bloom highly expressed nitrate transporters and carbonic anhydrase presumably to support high growth rates and enhance uptake of low levels of dissolved nitrate and CO2. Diatom-diazotroph association (DDA: diatoms with nitrogen fixing symbionts) blooms were common when surface salinity was mesohaline and dissolved nitrate concentrations were below detection, and hence did not show evidence of nitrate utilization, suggesting they relied on ammonium transporters to aquire recently fixed nitrogen. These DDA blooms in the outer plume had rapid turnover of the photosystem D1 protein presumably caused by photodegradation under increased light penetration in clearer waters, and increased expression of silicon transporters as silicon became limiting. Expression of these genes, including carbonic anhydrase and transporters for nitrate and phosphate, were found to reflect the physiological status and biogeochemistry of river plume environments. These relatively stable patterns of eukaryotic transcript abundance occurred over modest spatiotemporal scales, with similarity observed in sample duplicates collected up to 2.45 km in space and 120 minutes in time. These results confirm the use of metatranscriptomics as a valuable tool to understand and predict microbial community function.

The mean trophic position (TP) of mesozooplankton largely determines how much mass and energy is available for higher trophic levels like fish. Unfortunately, the ratio of herbivores to carnivores in mesozooplankton is difficult to identify in field samples. Here, we investigated changes in the mean TP of mesozooplankton in a highly dynamic environment encompassing four distinct habitats in the southern South China Sea: the Mekong River plume, coastal upwelling region, shelf waters, and offshore oceanic waters. We used a set of variables derived from bulk and amino acid nitrogen stable isotopes from particulate organic matter and four mesozooplankton size fractions to identify changes in the nitrogen source and TP of mesozooplankton across these habitats. We found clear indications of a shift in N sources for biological production from nitrate in near‐coastal waters with shallow mixed layer depths toward an increase in diazotroph‐N inputs in oceanic waters with deep mixed layer depths where diazotrophs shaped the phytoplankton community. The N source shift was accompanied by a lengthening of the food chain (increase in the TP). This may provide further support for the connection between diazotrophy and the indirect routing of N through the marine food web. Our combined bulk and amino acid δ15N approach also allowed us to estimate the trophic enrichment (TE) of mesozooplankton across the entire regional ecosystem. When put in the context of literature values, a high TE of 5.1‰ suggested a link between ecosystem heterogeneity and the less efficient transfer of mass and energy across trophic levels., Plain Language Summary: Zooplankton are one of the central pillars of the marine food web and form an important link between the production of organic matter by phytoplankton and biomass at higher trophic levels (e.g., fish). Of particular interest are mesozooplankton (0.2–20 mm in size), which encompass a diverse assemblage of animals utilizing a range of feeding strategies, including herbivory, omnivory, and carnivory. Since mass and energy are lost with each trophic step, their prevailing feeding strategy determines the availability of mass and energy to the upper food web. The exact relationship between carnivores and herbivores in mesozooplankton has so far only been studied with complex experiments or in homogenous environments. We have now resolved zooplankton feeding relationships in a highly dynamic marine environment. Specifically, we used stable nitrogen isotopes in amino acids and bulk organic matter in combination with a habitat‐delineating method for phytoplankton to directly determine the ratio of carnivores to herbivores in zooplankton from dynamic habitats in the South China Sea. The mass and energy transfer across trophic levels is less efficient in such variable marine environments compared to stable open ocean systems. These findings represent a big step toward understanding the dynamics of planktonic food webs in general., Key Points: Trophic structure of mesozooplankton is regulated by similar environmental factors such as phytoplankton assemblages. Diazotrophy and nutrient availability correlated with enhanced mesozooplankton carnivory in a complex tropical marine ecosystem. Mass and energy transfer across trophic levels of planktonic food webs are less efficient in spatially and temporally variable ecosystems., Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659, National Foundation for Science and Technology Development (NAFOSTED) http://dx.doi.org/10.13039/100007224, National Aeronautics and Space Administration (NASA) http://dx.doi.org/10.13039/100000104, Schmidt Ocean Institute, National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001, https://doi.org/10.5061/dryad.bk3j9kdbv