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Biofouling potential of surface-enhanced Raman scattering-based seawater quality sensors by Ulva spp.
No full textThis study investigated the biofouling potential of surface-enhanced Raman scattering (SERS)-based sensor materials in the context of marine environments. Uncoated and monolithic commercial gold (Au) silicon nanopillar array SERS substrates, Au-coated carbon black nanoparticle (AuCB NP) substrates, uncoated and Au sputter-coated in-house SERS, and uncoated and Au sputter-coated glass controls were tested for biofouling potential using Ulva spp. as model biofouling organisms. The mean percentages of Ulva spp. zoospores that adhered per mm2 (×103) on the uncoated and coated Au silicon nanopillar array, AuCB NP, uncoated and Au sputter-coated in-house, and uncoated and Au sputter-coated glass substrates were 10.28%, 5.45%, 10.49%, 3.25%, 24.84%, 12.86% and 7.78%, respectively. Results indicated that surface properties such as hydrophobicity, roughness, Au sputter-coating and the presence of micro-refuges on nano- and microstructured substrates were critical to the biofouling formation
Late Pleistocene-Holocene age and stratigraphy of the Currituck Slide Complex, U.S. mid-Atlantic continental slope: Implications for landslide triggering
No full textConsiderable effort has been made to link submarine slope failures to changes in local and global-scale environmental conditions, in order to assess landslide hazard probability. Here we provide the first radiocarbon dates of hemipelagic sediment overlying mass transport deposits and inferred failure surfaces of the Currituck Slide Complex (CSC), a prominent landslide scar on the U.S. mid-Atlantic continental slope. The dates, taken from both the upper and lower scars of the complex, constrain the age of the last major failure event to 13,835 and 16,020 years BP. Time correlation of the hemipelagic sediments across the landslide scar and proximal deposit suggests a single failure of both the upper and lower parts of this 160 km3 volume. A higher rate of sediment supply from the periglacial Appalachian Mountains and from glacial melt-water pulses, with an exposed continental shelf at that time, may have enlarged a shelf-edge delta at the site of the CSC, which may have facilitated or triggered failure. A smaller landslide at the southern edge of the complex with a less well-defined geomorphologic footprint is dated at 5500 BP and possibly represents the reshaping of the seafloor around the CSC triggered by low-frequency earthquakes on the nearby continental margin
Chitosan of blood cockle shell (Anadara granosa) as a natural coagulant for removal of total suspended solids (TSS) and turbidity of well-water
No full textBlood clam or blood cockle (Anadara granosa) is a clam species with high calcium carbonate (CaCO3) and chitin content; these compounds are commonly used in coagulation water treatment. This study examined the capacity of blood cockle shells (BCS) as an innovative natural coagulant in the form of unmodified powder (BCSP) and chitosan extracted from the shells (BCSC) to reduce TSS and turbidity of well-water. SEM and FTIR analysis were conducted to analyse the characteristics of the media. The coagulant dose, pH of the water sample, and settling time were investigated using a jar test experiment to determine the optimum condition for each experimental system. Rapid mixing (1 min at 120 rpm) was followed by slow mixing (10 min at 60 rpm), followed by settling times ranging from 10 to 30 min. The optimum settling time was 30 min, after which 76% TSS and 76% turbidity were removed using 75 mg/l of BCSP at pH 4. The tests with BCSC resulted in 80% TSS and 81% turbidity removal with 200 mg/l of BCSC at pH 5 and a settling time of 30 min. The results were compared to the performance of alum (Al2(SO4)3·18H2O), a commercial chemical coagulant. Under similar dosage (200 mg/L) and pH (= 6) conditions, alum reduced turbidity and TSS by 95% and 97%, respectively. These results indicate that blood cockle shell-based coagulant is a promising environmental-friendly material that can compete and possibly replace conventional chemical coagulants in water treatment systems
Multifunctional carbon/epoxy composites with power transmission capabilities
No full textThis study evaluates the power transmission of multifunctional composites with embedded conductors. The electrical conductors were constructed by braiding copper strands with Para-aramid fibers into a tape configuration, then placing these tapes within carbon/epoxy prepregs to create a multifunctional structure. Experiments were performed on these multifunctional composites under tensile loading conditions. During experimentation, the conductive tapes were incorporated within an electrical bridge to record their resistance change as a function of mechanical strain. The Digital Image Correlation (DIC) technique was used to obtain in-plane displacements and strains as a function of time. In addition, low-speed flight condition experiments with an airfoil shape composite system were carried out in a wind tunnel to study the temperature performance of these structures while under high currents. Computational models were then created to expand the experimental efforts and evaluate the system\u27s multiscale performance. Experimental results show that the mechanical load on the conductive tape is mainly carried by the Para-aramid yarns, leading to a relatively consistent electrical performance and airflow over the wind foil providing efficient power transmission. Lastly, the computational models showed consistency in the electrical/mechanical results and established a framework for analyzing multi-functional structures (MFS)
Behavior Analysis of the Binary Hyperbolic Tangent (Btanh) Algorithm
No full textThis paper seeks to analyze the behavior and potential uses of the binary hyperbolic tangent (Btanh) algorithm [1], an algorithm designed to provide the activation function in a specific type of stochastic artificial neuron. Differences between Btanh outputs when used with and without an associated parallel counter are explored, and output formulas for each case are estimated. The question of whether the Btanh module could be decoupled from a parallel counter and be useful for stochastic computing applications outside of neural networks is discussed as well. It is determined that the output bitstreams from a parallel counter leads to unique behavior from the Btanh module, as opposed to when the Btanh inputs are generated independently, and this must be taken into account when decoupling the two modules
Minoritized Scientists in the United States: An Identity Perspective to Science Communication
Get PDFThis study investigates how tenure-track faculty from historically marginalized groups in the environmental sciences approach science communication based on their self-identities. A thematic analysis of 28 in-depth interviews with U.S.-based participants using the Communication Theory of Identity and Border-Crossing Theory was conducted to explore the interrelation of layers of identity, the identity gaps participants experience, and their communication practices. The results show that communication merges fragments of identity not to form a fixed identity, but to create an evolving consciousness about who you are and how you communicate. Implications for science communication training are discussed
