Deposition Time Research Articles

Hydrogen resistance of reduced graphene oxide coatings prepared by electrophoretic deposition on duplex stainless steel

In this study, reduced graphene oxide (rGO) coatings were fabricated on duplex stainless steel (DSS) substrates using the electrophoretic deposition (EPD) method to evaluate their hydrogen resistance performance. The successful fabrication of rGO coatings was confirmed using Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). The structural characteristics were characterized using Raman spectroscopy and X-ray Diffraction (XRD). The results indicate that the EPD voltage is a crucial factor affecting the surface quality of and hydrogen resistance performance of rGO. Lower voltages resulted in lower degrees of rGO reduction and higher surface wrinkle density, while higher voltages caused bubble formation, significantly degrading the coating quality and hydrogen resistance performance. The optimal hydrogen resistance was achieved at an EPD voltage of 7.5V and a deposition time of 6 minutes. Electrochemical hydrogen charging tests and thermal desorption analysis (TDA) demonstrated that rGO coatings prepared under optimal conditions exhibited excellent hydrogen resistance efficiency, significantly reducing hydrogen atom penetration in hydrogen environments. The study further revealed that bubble formation significantly reduces the hydrogen resistance of rGO, which is attributed to increased interlayer spacing and the loss of the “labyrinth effect”.

Active and Passive Infrared Emittance Tuning Using Optically Transparent Unpatterned ITO Thin Films

Tailoring of thermal emittance has applications in smart radiators, camouflage, infrared (IR) scene generation, stealth, and thermal management. Various studies have explored avenues to achieve both passive and active emittance tuning using methods such as meta-surfaces, phase change materials, composites, nanostructure arrays and multi-layer stacks. Most of these methods often involve complex fabrication processes like multilayer depositions and micro/nano patterning, limiting their scalability for large-scale applications. This study presents a straightforward and scalable approach for passive and active emittance tuning using Indium Tin Oxide (ITO) films deposited on a high emissivity flexible polyethylene terephthalate (PET) substrate. By changing the deposition time, the thickness of the ITO film is controlled which changes the observed emissivity of the ITO/PET composite structure over a wide range (0.2-0.94) while maintaining optical transparency. Using this approach for passive emittance tuning, we demonstrate an IR scene generation application. As the ITO film is conducting, by applying voltage to the ITO/PET sheet, its temperature is changed using which active emittance tuning is also achieved. Compared to existing methods of emittance tuning, the presented approach is simpler, gives flexible films with optical transparency, and has the potential for large-scale integration, enabling cost-effective and scalable manufacturing of emittance-tuned surfaces.

Timing and geometry of the Chemehuevi Formation reveal a late Pleistocene sediment pulse into the Lower Colorado River

The Chemehuevi Formation is a distinctive 50−150-m-thick wedge-shaped Pleistocene sedimentary unit deposited by the Colorado River. It lines the perimeters of the river’s floodplains and bedrock canyons for more than 600 km between the mouth of the Grand Canyon and the delta region in the Gulf of California. The formation is composed of a basal tan to light-yellowish-brown and pale-orange mud-dominated facies overlain and interbedded by a light-yellow-brown sand-dominated facies. The unit is one of two extensively exposed aggradational packages in the Lower Colorado River corridor, in addition to a series of other smaller alluvial terrace deposits. The Chemehuevi Formation appears to represent the response of a fully integrated Colorado River system to a significant perturbation, in contrast to the Bullhead Alluvium, which is likely a unique result of Pliocene river integration. The aggradation of the Chemehuevi Formation in the Lower Colorado River corridor may be similarly due to a unique event in the Colorado River system, or it may instead be a well-preserved sedimentary sequence recording typical behavior of the Colorado River below the Grand Canyon in the late Pleistocene. As such, multiple causal mechanisms have been proposed, but no study to date has conclusively explained the Chemehuevi Formation. To help resolve its timing, duration, and origin, we applied post-infrared infrared stimulated luminescence, carbonate U-Th series, and zircon sensitive high-resolution ion microprobe U-Th series geochronology to determine the ages of key exposures of the unit over a wide spatial area. These new data demonstrate that the Chemehuevi Formation was deposited ca. 110−90 ka. The depositional ages collectively overlap, suggesting that deposition occurred rapidly relative to the resolution of the geochronometers. The new depositional timing coincides with a shift from glacial to interglacial conditions after the marine isotope stage 5-6 transition. This observation is consistent with a climate-induced sediment pulse as a causal mechanism, yet correlations with similar deposits in the Colorado River headwaters or in neighboring catchments appear elusive. Potentially, climate transitions between glacial and interglacial periods induced a sediment pulse from hillslopes of the Colorado River system that resulted in the Chemehuevi Formation. An alternative or additional explanation is that the Chemehuevi Formation represents release of lava dam−impounded sediment in the Grand Canyon. The surface geometry of the Chemehuevi Formation projects upstream to the approximate location of lava dams, and the largest possible lava dam impoundment (the Upper Prospect dam) is comparable in volume to the formation. The lava dam hypothesis appears to be a possible explanation for the Chemehuevi Formation. However, tying deposition to a specific lava dam or series of lava dams remains challenging due to discrepancies in timing and volume. The combined effects of a series of lava dams may have led to the Chemehuevi Formation, as the last Pleistocene lava dam eruption coincides with the onset of deposition. Alternatively, the formation may result from the combined effects of both regional climate transitions and the lava dams that created a transient reservoir to compound a climate transition−driven sediment pulse. The geochronologic data presented here do not allow us to distinguish between the lava dam or climate transition hypotheses but will need to be reconciled with any future proposed depositional model.

The effect of deposition time on the morphology of CuS electrodes fabricated by chemical bath deposition for supercapacitor applications

The effect of deposition time on the morphology of CuS electrodes fabricated by chemical bath deposition for supercapacitor applications

Surface modification of high-speed steel (HSS) drills by plasma nitriding and cathodic cage tin deposition

Cutting tools made of high-speed steel have significant economic and technological importance. To enhance their productivity, thermochemical treatments are sought to improve both surface mechanical and tribological properties. Plasma nitriding and thin film deposition are widely employed for this purpose. In this study, modifications were made to M2 high-speed steel drills through plasma nitriding at temperatures of 400°C and 450°C. Cathodic cage TiN plasma deposition was also performed, varying the dwell time at a fixed temperature of 450°C. Characterization techniques included optical microscopy, X-ray diffraction (XRD), Vickers microhardness testing, and scanning electron microscopy (SEM). Performance tests were carried out to evaluate the behavior of the drills in relation to wear when machining AISI 1020 steel. It was observed that longer deposition times promote more uniform and thicker layers, and higher nitriding temperatures result in thicker nitride layers. An increase in hardness was noticeable in all deposition and nitriding treatments, with the nitrided samples exhibiting the highest hardness. During performance tests, the cathodic cage plasma TiN deposition demonstrated greater potential for application in HSS drills, with a treatment lasting 4 h providing the best results.

Analisis Biaya Pengurasan Sedimentasi pada Kolam Pengendap Lumpur di PT Bukit Asam Tbk Unit Pertambangan Tanjung Enim Sumatera Selatan

PT Bukit Asam is one of the companies engaged in the coal mining sector which is located in Tanjung Enim, South Sematra. The mining system applied in exploiting coal is open pit mining which produces water called acid mine water (AAT), one of the components of the AAT problem. namely total suspended solid (TSS). At PT Bukit Asam, Bangko Barat, there are several KPLs that are still in use. KPLs that are continuously supplied with mining water certainly produce a negative impact, namely silting. The aim of this research is to analyze the cost of dewatering sedimentation in mud settling ponds. The method used in this research is to use field visits and direct observations. The shallowing itself is caused by rain factors and the long deposition time. To prevent silting, draining is carried out using an excavator and loading of the material using a dump truck. Draining activities in February amounted to IDR 185,634,400.00 handling the mud settling ponds also using chemicals or control methods which are useful for settling mud particles so that the draining process at the KPL runs quickly.

Improvement of curing efficiency and heat resistance of CFRP by the growth of SiCNWs on CF

Carbon fiber-reinforced polymer composites are widely used in modern industry. However, poor heat transfer between layers of carbon fiber cloth during the curing process leading to poor curing of the substrate, long curing cycles, and excessive heat accumulation has become an urgent problem to be solved. A common approach is dispersing highly thermally conductive fillers in the polymer matrix to improve the curing efficiency of the composites. Different from adding fillers, we report a novel method of in situ growth of SiC nanowires (SiCNWs) on the surface of carbon fiber (CF) by the chemical vapor deposition (CVD) method and study the effects of CVD deposition time on curing efficiency and thermal stability of the composites. The results indicate that the nano bridge effect of SiCNWs significantly improves the curing efficiency of the composites. Compared with pure CF/epoxy composites, the curing efficiency can be increased by 38.72%. The cross-linking point between SiCNWs and the resin matrix enhances the thermal stability of the composites and increases the heat resistance index ( T HRI) by 8.4°C.

Gold-enhanced aptasensors for highly sensitive dengue detection: a cost-effective approach

The reemergence of diseases such as Dengue has spurred the development of efficient biosensing devices. This study aims to establish a rapid, cost-effective, and efficient platform for Dengue detection. The surface of the sensor was constructed by sputtering gold onto fluorine-doped tin oxide thin films, that were previously deposited on glass substrates. Varied sputtering deposition times were used. Results obtained from X-Ray Diffraction analysis showed that the films with 4-minute deposition time had the best gold surface coverage and the best cost-benefit ratio for sensor fabrication. Subsequently, the gold thin films were functionalized with the co-immobilization of a self-organized monolayer of aptamers and 6-mercapto-1-hexanol (MCH). The monolayer was analysed using the electrochemical impedance spectroscopy technique, and the ratio of 1:25 (aptamer: total thiol) was determined for surface optimization. The performance of the aptasensor was tested for the detection of the non-structural protein 1 of Dengue serotype 4 (NS1-S4). A good sensitivity of 40.2 ± 3.7 % per decade and a low detection limit of 1.25 pg/mL were obtained. The development of this platform represents an advance in the fast fabrication of aptasensors for the detection of emerging diseases such as Dengue, contributing also to the miniaturization process of point-of-care devices.

Effect of solutions acidity on Haacke’s Figure of Merit of ZnO and ZnO:F thin films deposited by ultrasonic spray pyrolysis

Fluorine-doped zinc oxide (ZnO:F) thin films are valued for their potential as transparent conductive materials, particularly in optoelectronic applications. In this work, the deposition of highly conductive and transparent fluorine-doped ZnO thin films, deposited by chemical spray on glass substrates is reported. The effect of acetic (AcAc) in the initial fresh solution on Haacke’s Figure of Merit (Φ) of both zinc oxide (ZnO) and fluorine-doped zinc oxide (ZnO:F) thin films was studied. The substrate temperature was fixed to 450°C, and two deposition times (8 and 14 min) were tested. Accordingly, the optical and transport properties, as well as the structural and morphological characteristics of the films were measured. The results indicate that the samples are polycrystalline in all cases and exhibit a wurtzite-type structure of ZnO. The variation of AcAc in the starting solution causes a switch in preferential growth from (002) to (001). As the AcAc content increases, the surface morphology of the films reveals the formation of well-defined hexagonal grains, and the grain size increases. Conversely, the transmittance decreases as the acetic acid increases, which can attributed to carbon incorporation into the film. In addition, the band gap values of the films varied from 3.2 to 3.4 eV. Also, as the acetic acid concentration increased, a drop in the electrical resistivity of ZnO thin films on the order of 0.016 Ω⋅ cm was found for the ZnO:F films deposited with fresh solution for 14 min. This can be ascribed to a dense acetic cloud formed during the synthesis process, trapping volatile F species that incorporate into the ZnO lattice. This enhances Haacke’s Figure of Merit of ZnO:F films deposited with a fresh solution, demonstrating their potential use for application as transparent conductive films. This contrasts with other synthesis methods that require longer aging time in the precursor solution, making these findings useful for large-scale and more efficient production of transparent conductive films.

Discovery of the Callovian Oceanic Anoxic Event in the Qiangtang Basin, eastern Tethys: Insights from in situ calcite U[sbnd]Pb dating

Oceanic anoxic events (OAE) are global carbon-cycle perturbations and major paleoenvironmental changes documented by deposition of black shales rich in organic matter. Jurassic black shales exposed in the Biluo Co Section of the Qiangtang Basin (central Tibet) display a ∼ 3 % negative carbon isotope excursion (CIE) previously regarded as documenting the Toarcian T-OAE based on poorly preserved ammonites and one detrital zircon age. New biostratigraphic data on diagnostic calcareous nannofossils and ammonite assemblages have suggested a younger, Middle Jurassic age, thus raising doubts about the presence of the T-OAE in the Qiangtang Basin. We here present the first accurate in situ LA-ICPMS calcite UPb ages for carbonate layers intercalated in the Biluo Co section. Ages of 165.6 ± 3.7 Ma, 166 ± 16 Ma, and 164.0 ± 7.2 Ma obtained from two samples analyzed in two different laboratories indicate the Late Bathonian to mid-Callovian age, which is consistent with recent age assignments based on calcareous nannofossils and ammonites. Petrographic, geochemical, and C–O isotope analyses testify to only minor diagenetic effects, indicating that geochronological data do reflect the original timing of carbonate deposition. Therefore, the new age assignment does not document the T-OAE in the Qiangtang Basin, but possibly a younger, Callovian global-warming event.

Magnetron sputtered silicon thin films for solar cell applications

One of the important directions of research in photovoltaics is the development of new thin-film technology, which can replace the currently used, more expensive bulk silicon technology. The article discusses the findings from research focused on optimizing the parameters for the deposition of silicon thin films with P-type electrical conductivity for applications in photovoltaics. The growth rate was determined depending on the change in substrate temperature using reflectometry and the influence of deposition time on optical properties was determined using UV/VIS spectroscopy. Photovoltaic structures were made on substrates with an ITO layer and their electrical parameters were measured. The authors applied the magnetron sputtering method to deposit the layers, selecting it over the commercially used the chemical vapor deposition (CVD) method. This replacement could alleviate the necessity for high temperatures and broaden the potential applications of thin-film solar cells.

Optimization of deposition time on structural, morphological, and optical properties of Cd1-xZnxS nanocrystalline thin films

In this work, Cd1-xZnxS nanocrystalline thin films have been synthesized over a glass substrate by a simple and cost-effective Chemical Bath Deposition (CBD) technique at various deposition time keeping other deposition parameters constant. The structural, morphological, and optical properties are studied by incorporating a range of characterization techniques, including X-ray diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM), Energy Dispersive X-rays (EDX), and UV–Visible spectrophotometers (UV–Vis). The films have been deposited at five different deposition time in the range from 30 mins to 150 mins to record the changes which address in depth the structural, morphological and optical properties. Empirical fitting equations have also been developed to obtain a more quantitative analysis of the effect of deposition time. The results obtained in this work are compared with some recent reported works for performance analysis of the buffer layer. The proposed buffer layer deposited at 30 mins not only attains all the desirable qualities required for maximum extraction of solar energy but also a low-cost and environment friendly option, making it a potential candidate for solar cell and optoelectronic applications.

Microstructure and stress evolution of W nanofilms prepared by arc ion plating under different deposition time and substrate bias

Microstructure and stress evolution of W nanofilms prepared by arc ion plating under different deposition time and substrate bias

Efficient electrocatalytic CO2 reduction to ethylene using cuprous oxide derivatives.

Copper-based materials play a vital role in the electrochemical transformation of CO2 into C2/C2+ compounds. In this study, cross-sectional octahedral Cu2O microcrystals were prepared in situ on carbon paper electrodes via electrochemical deposition. The morphology and integrity of the exposed crystal surface (111) were meticulously controlled by adjusting the deposition potential, time, and temperature. These cross-sectional octahedral Cu2O microcrystals exhibited high electrocatalytic activity for ethylene (C2H4) production through CO2 reduction. In a 0.1M KHCO3 electrolyte, the Faradaic efficiency for C2H4 reached 42.0% at a potential of -1.376V vs. RHE. During continuous electrolysis over 10h, the FE (C2H4) remained stable around 40%. During electrolysis, the fully exposed (111) crystal faces of Cu2O microcrystals are reduced to Cu0, which enhances C-C coupling and could serve as the main active sites for catalyzing the conversion of CO2 to C2H4.

In Situ Electrochemical Conversion of Biomass-Derived 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid by Time-Controlled Aerosol-Assisted Chemical Vapor Deposited FeNi Catalyst.

The conversion of 5-hydroxymethylfurfural (HMF) into valuable chemicals, such as 2,5-furandicarboxylic acid (FDCA), is pivotal for sustainable chemical production, offering a renewable pathway to biodegradable plastics and high-value organic compounds. This pioneering study explores the synthesis of FeNi nanostructures via aerosol-assisted chemical vapor deposition (AACVD) for the electrochemical oxidation of HMF to FDCA. By adjusting the deposition time, we developed two distinct nanostructures: FeNi-40, which features nanowires with spherical terminations, and FeNi-80, which features aggregated spherical structures. X-ray diffraction (XRD) confirmed that both nanostructures possess a phase-pure face-centered cubic (FCC) crystal structure. Electrochemical tests conducted using FeNi nanocatalysts on Ni foam revealed that FeNi-40 requires a significantly lower onset potential for HMF oxidation (1.32 V vs RHE) compared to FeNi-80 (1.40 V vs RHE). This difference is attributed to the unique nanowire morphology of FeNi-40, which provides a higher density of active sites and a larger electrochemically active surface area, thereby enhancing the efficiency of the electrochemical process. When tested in an H-type electrolyzer with a Nafion membrane, FeNi-40 demonstrated a remarkable Faradaic efficiency of 96.42% and a high product yield, underscoring the potential of morphology-controlled FeNi nanostructures to enhance the efficiency of sustainable electrochemical processes significantly.

Investigation of Titanium Nitride as an Effective Interphase for Carbon-Fiber-Reinforced Silicon Carbide Ceramic Matrix Composites.

Ceramic matrix composites (CMCs) have played a significant role in increasing the efficiency of gas turbine engines. CMCs combine the high temperature resistance of ceramics with the high mechanical strength of ceramic fibers into a single unit. Interphase layers are a crucial component in CMCs, as they prevent ceramic fibers from oxidation and introduce strengthening mechanisms into the composite. Hexagonal boron nitride and pyrolytic carbon are the most commonly used interphase layers in the aerospace industry. Other than that, very few materials have been evaluated as interphase layers. In this study, we explore the possibilities of using titanium nitride as an interphase layer in single-tow CMCs (mini composite) representative of a unidirectional composite at a smaller scale. T-300 carbon fibers were coated with TiN by atmospheric pressure chemical vapor infiltration using TiCl4, N2, and H2. The deposition temperature, precursor flow rate ratio, total precursor flow rate, and deposition time were optimized to obtain high-quality coatings. The best coating was produced at 800 °C, 4:1 H2 [TiCl4]/N2 ratio, 125 standard cubic centimeters per minute (N2 + H2 [TiCl4]) total flow precursor flow rate, and 2 h of deposition time. At these conditions, the coatings displayed good fiber coverage, good fiber adhesion, minimum fiber linkage, and minimum surface roughness. There was minimum fiber degradation after TiN coating, with a retention of 95% of the initial Young's modulus and 26% of the ultimate tensile strength of the carbon fiber. Adding the TiN interphase coating to the Cf/SiC CMC increased the ultimate tensile strength of the composite by 1122% and Young's modulus by 150%.

Label-free and sensitive detection of Citrus Bark Cracking Viroid in hop using Ti3C2Tx MXene-modified genosensor

Since the discovery of Citrus bark cracking viroid (CBCVd) in hops in 2007, affected hop-growing countries such as Slovenia and Germany have been actively pursuing efficient and easily accessible diagnostic tools that could contribute to the early detection of CBCVd in the field. In the early stages of CBCVd infection, typical symptoms or subtle signs of spread may not be evident. Detection becomes feasible only when the plant begins to display symptoms. Unfortunately, there is currently no treatment available, which requires the removal of infected plants as the only viable solution. However, this approach leads to significant economic losses on a large scale. This work demonstrates the development and study of a sensitive, selective, and label-free impedimetric genosensor for the detection of CBCVd in total RNA hop samples. The genosensor is based on a supporting glassy carbon electrode modified with streptavidin-agarose beads, which serve as an effective immobilization layer for a biotinylated single-stranded DNA capture probe. The integration of a 2D-layered Ti3C2Tx MXene into the sensing architecture resulted in a significantly improved electroanalytical performance of the genosensor. Several fabrication and operational parameters were optimized, such as the streptavidin-agarose beads deposition time, capture probe immobilization time and concentration, and sample incubation time. The optimized genosensor exhibited a limit of detection of only 0.5 fg μL⁻¹ (5.5 fmol L−1) in combination with a one-hour incubation with the denatured total RNA hop extract, thus eliminating the need for an additional and laborious amplification step.

Assessment of bi-metal paleo-redox proxies in the Bakken Formation black shales, Williston Basin, North Dakota, USA

The influence of paleoredox conditions and water-mass restriction on trace metal (TM) accumulation in the lower (LBS) and upper black shales (UBS) of the Devonian–Mississippian (D–M) Bakken Formation was assessed utilizing V/Cr, V/(V + Ni), Ni/Co, U/Th, and enrichment factors (EF) for Mo vs. U. These assessments were compared to previously published estimates based on degree of pyritization (DOPT), sulfur‑iron and C–S–Fe relationships, and sedimentological data. Bi–metal ratios suggest >80 % of samples were deposited under suboxic to anoxic/euxinic conditions, whereas DOPT results suggest >60 % of samples were deposited under dysoxic (0.42–0.75 DOPT) bottom–water conditions. DOPT results are in good agreement with C–S–Fe and total S vs. Fe assessments of paleoredox conditions and sedimentological evidence. Good agreement is also seen between Mo/TOC and Mo EF/U EF that both suggest the Bakken shales were deposited under a relatively unrestricted water mass conditions resulting in consistent renewal of TMs into the basin. With TM resupply outpacing drawdown, the basin could support enhanced primary productivity as well as high concentrations of TMs. Trace metal concentrations for the Bakken Fm. show considerable range for Co (0–10,324 ppm), Mo (0–2018 ppm), Ni (0–1574 ppm), U (0–1604 ppm), and V (0–3194 ppm), and bi–metal ratios for the Bakken Fm. are up to 5× greater than those reported for other D–M black shale formations. Bivariate and principal component analysis indicate Mo, Ni, U, and V accumulation was more closely associated with the organic fraction than with reducing conditions, thus accumulation of organic matter during deposition and generation, migration, and biodegradation of hydrocarbons during diagenesis may have influenced the accumulation and distribution of these TMs. Furthermore, changes in biogeochemical processes during the D–M transition may have fundamentally altered marine chemistry, with the evolution of vascular land plants and enhanced terrestrial weathering leading to an increased influx of nutrients into marine waters resulting in the Annulata, Dasberg, and Hangenberg black shale events. Factors controlling TM accumulation during time of deposition (e.g., TM availability, bottom-water redox conditions, adsorption onto organic matter) and during diagenesis and catagenesis (e.g., alteration and break down of organic matter, movement of fluid hydrocarbons or other basinal fluids) likely contribute to the lack of agreement between redox proxies, and subsequently, the lack of applicability of bi–metal ratios in assessing bottom–water conditions for the Bakken shales. Therefore, it is suggested that these bi-metal redox proxies are not an effective means to describe bottom-water conditions during the deposition of the Bakken shales.

In situ and one-step electrodeposition growth of PtNi alloys on Ni foam for electrochemical ammonia-nitrogen sensing

The presence of ammonia-nitrogen in aquatic ecosystems has recently been recognized as a significant threat to public and ecological health. Hence, it is crucial to develop a reliable method for accurately quantifying low levels of this pollutant in the aquatic environment. In this work, PtNi alloys of varying compositions were fabricated via a one-step in-situ electrodeposition process on a Ni foam surface. The electrochemical catalytic performances for the ammonia oxidation reaction have been measured via the cyclic voltammetry (CV) technique. The experimental results demonstrated that the PtNi alloy exhibited the highest catalytic capability with the current density of 21.387 mA cm−2 for the ammonia oxidation reaction, when the ratio of H2PtCl6·6 H2O and Ni(NO3)2·6 H2O was 3:1 with the deposition time of 1500 s. Under the most favorable conditions, the electrochemical detection performance of the PtNi alloy in detecting ammonia-nitrogen has been extensively assessed based on the differential pulse voltammetry (DPV) technique. The experiments confirmed that the PtNi alloy demonstrated an outstanding sensitivity, reaching a remarkable value of 0.0255 mA µM−1, with a broad linear range from 3 µM to 500 µM. The PtNi alloy also demonstrated a remarkable low limit detection of 0.89 µM. In addition, Further evaluation of the anti-interference ability, reproducibility, stability and recovery in real sample analysis including tap water, lake water and sea water revealed that the PtNi alloy exhibited superior performance for detecting ammonia-nitrogen.

Provenance of Paleogene Strata at Slim Buttes, South Dakota: Implications for post-Laramide Evolution of Western Laurentia

Slim Buttes is a 30 km long by 10 km wide set of buttes containing Paleogene strata in northwest South Dakota. At Reva Gap in northern Slim Buttes, Eocene-Oligocene terrestrial strata of Chadron and Brule Formations of the White River Group unconformably overlie the Paleocene Fort Union Formation. An angular unconformity separates the White River Group from overlying Oligocene and Miocene strata of the Arikaree Group. Using detrital zircon U-Pb ages, we determine the provenance of these rocks as part of a broader synthesis of post-Laramide sedimentation in the Rocky Mountains and western Great Plains. The Chadron Formation age spectrum is dominated by Cretaceous and Proterozoic grains that are interpreted to be locally recycled from the underlying Cretaceous and Paleocene strata. The Brule Formation has a maximum depositional age of ~34 Ma; Paleogene zircons dominate the age spectrum, and a wide variety of older zircons are also present. The Oligocene zircons are interpreted to have been sourced from volcanic systems in the Great Basin to the southwest, while the subsequent proportions of the zircons were derived from a variety of source areas in the Nevadaplano and Rocky Mountain areas to the southwest. Sparse amounts of Archean zircons are thought to represent the burial of Laramide uplifts throughout Wyoming at the time of Brule deposition, making for a regional paleotopography with little relief across the western interior of the United States. The Miocene-age Arikaree Group sand has a maximum depositional age of ~26 Ma and a multimodal detrital zircon age spectrum. The Arikaree Group provenance likely represents continued sourcing in the Great Basin volcanic systems and Nevadaplano, the beginnings of the re-exhumation of Laramide basement uplifts, and subsequent sediment evacuation out of the western interior and into the Gulf of Mexico to the southeast. Our findings indicate that the transport process and detrital zircon provenance signatures of these strata are decoupled, and each have their own independent evolution. The volcanic signature is primarily transported via aeolian processes (i.e. volcanic ash), and the recycled detrital zircon signature is primarily transported via fluvial processes.