South Dakota School of Mines and Technology
  • Rapid City, SD, United States
Recent publications
The present study has been designed to utilize industrial and agricultural solid waste for NPK (Nitrogen–Phosphorus–Potassium) bio-organic fertilizer production and its optimized use. The collagenic material of wet blue leather (WBL) from leather industry was used as nitrogen source, after H3PO4 acid-mediated chromium removal. Chicken meat-bone meal (CMBM) and rice husk ash (RHA) are abundantly available locally, had used as P, K, and Ca sources. The presence of N, P, K, Ca in the produced bio-organic NPK fertilizer were 10.76, 11.03, 3.41, 13.64, respectively as per mixing ratio of ingredients. In this study it was effect on the chili plant (Capsicum annuum L.) growth and revealed 1.15 and 1.03 fold higher plant growth, 1.40 and 1.18 fold higher total chlorophyll content than untreated soil (control), and chemical fertilizer. The liberation of fertilizers components from their source, transport of fertilizer components in the soil, and absorption in plant roots have been studied using mathematical models indicating the optimum fertilizer use for better productivity and to reduce loss of extra fertilizer and eutrophication. The formulation showed excellent water retention capability (3.2 L/kg), which might increase soil water availability to the plants and eventually reduce water demand and labour cost. DNA intercalation study proved there is no harm to use this fertilizer.
Engineered nanomaterials (ENMs) are widely applied to meet the continuing market demand in a wide array of fields. The physicochemical properties of anthropogenic and natural nanomaterials might vary from those corresponding bulk materials in numerous ways, such as aspect ratio, reactivity, chemical composition, and toxicity. More importantly, such ENMs can undergo potential biophysicochemical transformations in the air, including physical, chemical, and biological reactions with atmospheric components such as humidity, vapors, gases, colloids, light, etc. Hence, the development of ENMs can bring significant unexplored risk factors for humans and the environment, which require substantial attention. Plants represent the major interface between the ecological system and environment, and they provide a large surface area for ENMs exposure through aboveground biomass such as leaf, and may serve as a potential pathway for ENMs transport and a route for bioaccumulation into the food chain. Therefore, it is important to understand the interactions between ENMs and plants. In this chapter, the potential transformations of ENMs in the air are discussed. Subsequently, the interactions of airborne ENMs with plant surface, including the uptake pathway, translocation pathway, and biotransformation of ENMs in plants, are explained. Finally, the negative and positive impacts of airborne ENMs on the plants are discussed.
Fe-based metal-amorphous nanocomposites (MANCs) are the subject of many contemporary studies for their unique tunable soft-magnetic properties. The alloys can exhibit some of the smallest losses and highest power storage capabilities of available materials used in electromagnetic inductors. Here, the magnetic and mechanical properties of Fe72.5Nb2Mo2Cu1Si15.5B7 at.%, Fe68.5Co5Ta3Cu1Si16.5B6 at.%, Fe68.5Co5Ta3Cu1Si16B6.5 at.%, and Fe73.5Ta3Cu1Si16B6.5 at.% melt-spun alloys were investigated in relation to their ability to be stress-annealed to tune permeability while simultaneously minimizing losses in tape-wound inductor cores. Mechanical and physical properties of the as-cast and processed ribbons including relaxation and crystallization temperatures and failure strains were measured using thermomechanical analysis (TMA), uniaxial tension, and bend tests to help inform the stress-annealing parameters. Magnetic properties were measured for the as-cast and stress-annealed materials in both wound-cores and flat ribbon strips. The alloys exhibited severe embrittlement during heating, thus creating significant challenges when tuning magnetic properties with an in-line stress-annealing (SA) process. However, when conditions were optimized, core losses as low as 1.14 W·kg⁻¹ were obtained when cores were excited at 10 kHz to a maximum induction field of 0.1 T, which are among the lowest reported in the literature. Based on this preliminary effort, understanding of the stress state in amorphous precursor ribbons prior to SA could reveal the key to developing more robust in-line SA processes for brittle Fe-based MANCs.
The refining process of petroleum crude oil generates asphaltenes, which poses complicated problems during the production of cleaner fuels. Following refining, asphaltenes are typically combusted for reuse as fuel or discarded into tailing ponds and landfills, leading to economic and environmental disruption. Here, we show that low-value asphaltenes can be converted into a high-value carbon allotrope, asphaltene-derived flash graphene (AFG), via the flash joule heating (FJH) process. After successful conversion, we develop nanocomposites by dispersing AFG into a polymer effectively, which have superior mechanical, thermal, and corrosion-resistant properties compared to the bare polymer. In addition, the life cycle and technoeconomic analysis show that the FJH process leads to reduced environmental impact compared to the traditional processing of asphaltene and lower production cost compared to other FJH precursors. Thus, our work suggests an alternative pathway to the existing asphaltene processing that directs toward a higher value stream while sequestering downstream emissions from the processing.
High-energy tau neutrinos are rarely produced in atmospheric cosmic-ray showers or at cosmic particle accelerators, but are expected to emerge during neutrino propagation over cosmic distances due to flavor mixing. When high energy tau neutrinos interact inside the IceCube detector, two spatially separated energy depositions may be resolved, the first from the charged current interaction and the second from the tau lepton decay. We report a novel analysis of 7.5 years of IceCube data that identifies two candidate tau neutrinos among the 60 “High-Energy Starting Events” (HESE) collected during that period. The HESE sample offers high purity, all-sky sensitivity, and distinct observational signatures for each neutrino flavor, enabling a new measurement of the flavor composition. The measured astrophysical neutrino flavor composition is consistent with expectations, and an astrophysical tau neutrino flux is indicated at 2.8 $$\sigma $$ σ significance.
Synthesizing patchy particles with predictive control over patch size, shape, placement and number has been highly sought-after for nanoparticle assembly research, but is fraught with challenges. Here we show that polymers can be designed to selectively adsorb onto nanoparticle surfaces already partially coated by other chains to drive the formation of patchy nanoparticles with broken symmetry. In our model system of triangular gold nanoparticles and polystyrene-b-polyacrylic acid patch, single- and double-patch nanoparticles are produced at high yield. These asymmetric single-patch nanoparticles are shown to assemble into self-limited patch‒patch connected bowties exhibiting intriguing plasmonic properties. To unveil the mechanism of symmetry-breaking patch formation, we develop a theory that accurately predicts our experimental observations at all scales—from patch patterning on nanoparticles, to the size/shape of the patches, to the particle assemblies driven by patch‒patch interactions. Both the experimental strategy and theoretical prediction extend to nanoparticles of other shapes such as octahedra and bipyramids. Our work provides an approach to leverage polymer interactions with nanoscale curved surfaces for asymmetric grafting in nanomaterials engineering.
This chapter considers the reproducibility of Mr. Pickwick from Charles Dickens’s The Posthumous Papers of the Pickwick Club (1836–1837) across autographic and allographic extensions, focusing on G.W.M. Reynolds’s allographic sequel, Pickwick Abroad; or, The Tour in France, first serialized in The Monthly Magazine from December 1837 until June 1838 and afterward published in monthly shilling parts. Pickwick Abroad was offered at the same shilling price point as Dickens’s original monthly parts, a price point that indicates that Reynolds was initially targeting an audience of the same socio-economic class. In 1840–1841, Dickens resurrected Mr. Pickwick in the autographic miscellany, Master Humphrey’s Clock. Yet, Dickens’s very use of Mr. Pickwick in Master Humphrey’s Clock betrays that the character can persist across the textual boundaries of distinct works. I use the example of Mr. Pickwick to argue that early nineteenth-century transfictional reception practices are conditioned by the rise of novelistic realism and the explosion of the print market through the eighteenth century and into the early nineteenth century. I propose that transfictionality likely emerges from fundamental psychological schemata for thinking about the hypothetical—namely, the perception of object permanence—and that these psychological schemata persist despite changes in intellectual property law. Claims regarding transfictional character were not just limited to those concerning Dickens’s intellectual property, but were also importantly mediated by narrative form, the psychology of reception, and the socio-economic dynamics of the British entertainment market.
Improvements to internal combustion engine performance can be achieved by the application of advanced coatings to piston rings and cylinder bores. Here, the sliding wear performance of TiSiCN coatings on ductile iron was evaluated in heavy-duty diesel engine oil using a block-on-ring tribometer. The coatings were deposited by plasma-enhanced magnetron sputtering of titanium in a reactive environment containing nitrogen, acetylene, and hexamethyldisilazane. Coating characterization was conducted using X-ray spectroscopy and diffraction, electron microscopy, and nanoindentation. TiSiCN adhesion to ductile iron was qualified by Rockwell indentation testing. Wearing surface and counter surface material pairs were systematically varied. Intermittent friction oscillation was observed for self-mated TiSiCN, while tribosystems with only one TiSiCN surface exhibited improved friction stability relative to uncoated ductile iron. A 24% reduction in block wear rate was achieved by coating the block surface with TiSiCN. Solely coating ring surfaces with TiSiCN, however, increased the uncoated block wear rate by over 300%.
Herein, core‐shell nanostructured ZnO/ZnFe2O4derived from self‐sacrifice template method with Prussian blue analogue (i.e., Zn3[Fe(CN)6]2) as precursor has been successfully synthesized by controlling the calcination temperatures and heating rates. The formation mechanism of core‐shell nanostructures has been explored through the morphology transformation under different synthetic conditions. Impressively, ZnO/ZnFe2O4 hybrid material with core‐double shell nanostructure shows good cycling performance as anodes of lithium‐ion batteries (1137 mAh g−1 at 1 A g−1 after 80 cycles) and potassium‐ion batteries (217 mAh g−1 at 0.1 A g−1 after 400 cycles). The excellent performances can be attributed to the unique core‐double shell nanostructure as well as synergistic effects of ZnO and ZnFe2O4. The results indicate that the strategy of designing nanostructures could successfully improve the electrochemical performances of ZnO/ZnFe2O4 and effectively expand the commercial application of transition metal oxides.
Solutions with high pH values are sometimes thought to contain net negative charge because of an excess of OH- groups, while solutions with low pH values are thought opposite. To follow up on these speculations, we used a simple electrochemical cell to study three types of solution: electrolyzed waters with differing pH values; acids and bases with different pH values; and various salt solutions. When electrolyzed waters of various pH values were tested against water of pH 7, we found that acidic waters were indeed positively charged, while basic waters were negatively charged. We found much the same when standard acids and bases were compared to reference solutions: acidic solutions were positively charged while basic solutions were negatively charged. Various salts, including NaCl, KCl, Na2SO4, and K2SO4, were also tested against DI water (containing trace amounts of NaCl to lend conductivity). Surprisingly, all salts were found to be negatively charged, more so as their concentrations increased. This collection of results supports the hypothesis that at least some aqueous solutions may contain net charge.
The Nucleic Acid Circular Dichroism Database (NACDDB) is a public repository that archives and freely distributes circular dichroism (CD) and synchrotron radiation CD (SRCD) spectral data about nucleic acids, and the associated experimental metadata, structural models, and links to literature. NACDDB covers CD data for various nucleic acid molecules, including DNA, RNA, DNA/RNA hybrids, and various nucleic acid derivatives. The entries are linked to primary sequence and experimental structural data, as well as to the literature. Additionally, for all entries, 3D structure models are provided. All entries undergo expert validation and curation procedures to ensure completeness, consistency, and quality of the data included. The NACDDB is open for submission of the CD data for nucleic acids. NACDDB is available at:
Along their long propagation from production to detection, neutrinos undergo flavour conversions that convert their types or flavours1,2. High-energy astrophysical neutrinos propagate unperturbed over a billion light years in vacuum3 and are sensitive to small effects caused by new physics. Effects of quantum gravity4 are expected to appear at the Planck energy scale. Such a high-energy universe would have existed only immediately after the Big Bang and is inaccessible by human technologies. On the other hand, quantum gravity effects may exist in our low-energy vacuum5–8, but are suppressed by inverse powers of the Planck energy. Measuring the coupling of particles to such small effects is difficult via kinematic observables, but could be observable through flavour conversions. Here we report a search with the IceCube Neutrino Observatory, using astrophysical neutrino flavours9,10 to search for new space–time structure. We did not find any evidence of anomalous flavour conversion in the IceCube astrophysical neutrino flavour data. We apply the most stringent limits of any known technologies, down to 10−42 GeV−2 with Bayes factor greater than 10 on the dimension-six operators that parameterize the space–time defects. We thus unambiguously reach the parameter space of quantum-gravity-motivated physics. The IceCube Collaboration reports a search for quantum gravity effects imprinted in flavour conversions of astrophysical neutrinos. No evidence for anomalous conversions between neutrino flavours is observed.
Fossils exposed at the surface are an integral component of the paleontologic record and provide an archive of past life. However, it is widely known that fossils are not stable indefinitely upon exposure to surface conditions such as physical, chemical, and biological processes, and this last phase of taphonomy is poorly understood. Studies regarding the longevity of fossils subject to weathering, such as acidic precipitation, are absent in the literature. The goal of this study was to experimentally determine vertebrate fossil dissolution rates under variable pH conditions in a controlled laboratory setting. It was hypothesized that fossils would dissolve within acidic solutions and do so at an increasing rate when exposed to increasingly acidic solutions. The experiments were conducted on three fossil vertebrae in triplicate in closed reaction vessels at pH 4, 5, and 6. The fossils were completely submerged for 21 days in a tap water solution with the pH adjusted using 0.1N hydrochloric acid (HCl). Fossil dissolution was quantified by changes to: (1) fossil mass; (2) elemental chemistry of water and fossils with inductively coupled plasma mass spectrometry (ICP-MS); (3) fossil mineralogy with X-ray diffraction (XRD); and (4) histologic structures with thin section analyses. All fossils exhibited mass loss, which increased with decreasing pH conditions, and was greatest under pH 4 (477 to 803 mg loss). The elemental analyses with ICP-MS indicated an increase of both calcium (maximum increase of 315 ppm) and phosphorus (increase of 18 ppm) in aqueous solutions with increasing pH and a loss of those same elements from the fossils (maximum loss of 10 ppm Ca and 6 ppm P). XRD revealed loss of gypsum in all post-dissolution samples. Taken together, the results of ICP-MS and XRD suggest dissolution of the primary mineral phases, including hydroxylapatite, and secondary phases, particularly calcite and gypsum, resulting in an estimated mass loss at pH 4 of 23 to 28 mg per day. Thin section analysis showed degradation of both cortical and trabecular bone in all post-dissolution images, demonstrating physical changes to the fossils as a result of water-rock interactions. These findings constitute the first quantitative analysis of fossil dissolution rates and provide insights into this last stage of taphonomy, addressing a largely understudied potential bias in the vertebrate fossil record.
In this paper, we illustrate our study of using genetic algorithms and machine learning to create an ensemble technique, which is used to predict tennis games using limited amounts of data. The genetic algorithm was used to improve the game representations, derived from the players’ statistics differences, to be utilized by the machine learning algorithms. The use of genetic algorithms also reduced the dependence on human expertise in creating the game representations. The majority of the ensemble models we generated were either as good or performed higher than the predictions based on just the player’ official rankings.
The elemental contributions to the conduction bands of the transition-metal trichalcogenides TiS3 and ZrS3 were examined using X-ray absorption spectroscopy, at the Ti and S 2p edges and the Zr 3p edges. A comparative study of these two compounds shows that the bottom of the conduction band, for both TiS3 and ZrS3, is comprised mainly of hybridized transition metal-sulfur orbitals, either Ti 3d and S 3p orbitals or Zr 4d and S 3p orbitals. Density functional theory and experiment both indicate that the bottom of the conduction band, in the case of TiS3, has the Ti 3d weight. Although weak, experiment indicates that the S-weighted contribution to the conduction band minimum for ZrS3 is greater than in the case of TiS3. For ZrS3, theory, however, indicates that the conduction band is dominated by hybridization of the Zr 4d and S 3p orbitals, including in the vicinity of the bottom of the conduction band.
We present a search for an unstable sterile neutrino by looking for a resonant signal in eight years of atmospheric νμ data collected from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable) three-neutrino and the 3+1 sterile neutrino models are disfavored relative to the unstable sterile neutrino model, though with p values of 2.8% and 0.81%, respectively, we do not observe evidence for 3+1 neutrinos with neutrino decay. The best-fit parameters for the sterile neutrino with decay model from this study are Δm412=6.7−2.5+3.9 eV2, sin22θ24=0.33−0.17+0.20, and g2=2.5π±1.5π, where g is the decay-mediating coupling. The preferred regions of the 3+1+decay model from short-baseline oscillation searches are excluded at 90% C.L.
In this article, we develop a new waveform codesign approach for radar–communications spectral coexistence using a decision-theoretic framework called partially observable Markov decision process (POMDP). The POMDP framework’s natural look-ahead feature allows us to trade off short-term for long-term performance, which is necessary in waveform codesign problems with competing objectives and dynamic user needs. As POMDPs are computationally intractable, we extend two approximation methods called nominal belief-state optimization and random-sampling multipath hypothesis propagation to make the codesign approaches tractable.
Microbialites provide a record of the interaction of microorganisms with their environment constituting a record of microbial life and environments through geologic time. Our capacity to interpret this record is limited by an incomplete understanding of the microbial, geochemical, and physical processes that influence microbialite formation and morphogenesis. The modern system Laguna Negra in Catamarca Province, Argentina contains microbialites in a zone of carbonate precipitation associated with physico‐chemical gradients and variable microbial community structure, making it an ideal location to study how these processes interact to drive microbialite formation. In this study, we investigated the geospatial relationships between carbonate morphology, geochemistry, and microbial community at the macro‐ (decimeter) to mega‐ (meter) scale by combining high‐resolution imagery with field observations. We mapped the distribution of carbonate morphologies and allochtonously‐derived volcaniclasts and correlated these with sedimentary matrices and geochemical parameters. Our work shows that the macroscale distribution of different carbonate morphologies spatially correlates with microbial mat distributions—a result consistent with previous microscale observations. Specifically, microbialitic carbonate morphologies more commonly occur associated with microbial mats while abiotically derived carbonate morphologies were less commonly associated with microbial mats. Spatial variability in the size and abundance of mineralized structures was also observed, however, the processes controlling this variability remains unclear and likely represent a combination of microbial, geochemical, and physical processes. Likewise, the processes controlling the spatial distribution of microbial mats at Laguna Negra are also unresolved. Our results suggest that in addition to the physical drivers observed in other modern environments, variability in the spatial distribution of microbialites and other carbonate morphologies at the macro‐ to megascale can be controlled by microbial processes. Overall, this study provides insight into the interpretation of microbialite occurrence and distributions in the geologic record and highlights the utility of geospatial statistics to probe the controls of microbialite formation in other environments.
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940 members
Obuli Karthik
  • Department of Civil and Environmental Engineering
Rajesh Sani
  • Department of Chemical and Biological Engineering
Sayan Roy
  • Department of Electrical and Computer Engineering
Ram Nageena Singh
  • Department of Chemical and Biological Engineering
501 E Saint Joseph St, 57701, Rapid City, SD, United States
Head of institution
Dr. James Rankin