Louisiana State University
  • Baton Rouge, LA, United States
Recent publications
Background Numerous genome-wide association studies (GWAS) conducted to date revealed genetic variants associated with various diseases, including breast and prostate cancers. Despite the availability of these large-scale data, relatively few variants have been functionally characterized, mainly because the majority of single-nucleotide polymorphisms (SNPs) map to the non-coding regions of the human genome. The functional characterization of these non-coding variants and the identification of their target genes remain challenging. Results In this communication, we explore the potential functional mechanisms of non-coding SNPs by integrating GWAS with the high-resolution chromosome conformation capture (Hi-C) data for breast and prostate cancers. We show that more genetic variants map to regulatory elements through the 3D genome structure than the 1D linear genome lacking physical chromatin interactions. Importantly, the association of enhancers, transcription factors, and their target genes with breast and prostate cancers tends to be higher when these regulatory elements are mapped to high-risk SNPs through spatial interactions compared to simply using a linear proximity. Finally, we demonstrate that topologically associating domains (TADs) carrying high-risk SNPs also contain gene regulatory elements whose association with cancer is generally higher than those belonging to control TADs containing no high-risk variants. Conclusions Our results suggest that many SNPs may contribute to the cancer development by affecting the expression of certain tumor-related genes through long-range chromatin interactions with gene regulatory elements. Integrating large-scale genetic datasets with the 3D genome structure offers an attractive and unique approach to systematically investigate the functional mechanisms of genetic variants in disease risk and progression.
Polyester in the textile industry is frequently mixed with cotton fibers to produce PET-CO blend fabrics, widely used in clothing and home textiles. However, polyester’s slow degradation (up to 400 years) and the production of cotton and PET are related to environmental impacts. Brazil is prominent in the cotton production scenario due to the quality and volume of its production, although of environmental damages and health issues to farmworkers. Blend fibers, being a junction between natural and synthetic ones, carry the impacts of both productions. This study aimed to compare the environmental impacts of pure cotton and PET-CO (blended polyester and cotton) productions. A bibliographic analysis of literature and reports from sectorial organizations was carried out, resulting in data and knowledge about the environmental impacts caused by textile and clothing production related to cotton and polyester-cotton blend and other actions turned to reduce or nullify these impacts towards the circular economy, with emphasis to textile recycling. The adoption of the circular economy needs to be deeply understood so that the textile waste returns to the beginning of the production cycle, as well as the need to improve the production processes to avoid polluting and losses of energy, water, and other resources through actions, such as the correct separation and disposal of waste.
Magnetic semimetals are very promising for potential applications in novel spintronic devices. Nevertheless, realizing tunable topological states with magnetism in a controllable way is challenging. Here, we report novel magnetic states and the tunability of topological semimetallic states through the control of Eu spin reorientation in Eu1−xSrxMn1−zSb2. Increasing the Sr concentration in this system induces a surprising reorientation of noncollinear Eu spins to the Mn moment direction and topological semimetallic behavior. The Eu spin reorientations to distinct collinear antiferromagnetic orders are also driven by the temperature/magnetic field and are coupled to the transport properties of the relativistic fermions generated by the 2D Sb layers. These results suggest that nonmagnetic element doping at the rare earth element site may be an effective strategy for generating topological electronic states and new magnetic states in layered compounds involving spatially separated rare earth and transition metal layers.
Coastal erosion is widespread under conditions of changing hydrodynamics and diminishing sediment supply, and exposure assessment to erosion hazard has received increasing attention. In this study, we explore the impact of spatial heterogeneity of land use within administrative units on exposure assessment of land use value to erosional hazard. We illustrate land use diversity using the Shannon’s diversity index (SHDI) and consider the distance effect by comparing five different buffer zones according to the distance to the coast (i.e., 0–1 km, 0–2 km, 0–3 km, 0–4 km, 0–5 km). Our results show that coastline change and socio-economic development are responsible for land use heterogeneity within the administrative units. Using a buffer zone of 1-km along the coast as the assessment unit leads to an increase in the number of townships that have high and very high exposure of land use value when compared with the assessment result that is based on the whole township area. Furthermore, the 1-km buffer zone can be divided into subunits if very high SHDI values exist within the administrative boundary. This study demonstrates that heterogeneity in land use identified at a fine spatial scale should be given full consideration in carrying out exposure assessment to hazards in a dynamic deltaic coast.
Fracturing fluids used hydraulic fracturing in energy industry are formulated to have superior rheological properties for suspending and transporting rigid proppants into the fractures. Herein, we report the utilization of lignin-containing cellulose nanomaterials (LCNMs) to enhance the rheological properties of viscoelastic fracturing fluids (VFFs) based on borax-crosslinked guar gum (GG) gels. Two types of LCNMs, i.e., lignin-containing cellulose nanofibers (LCNFs) from energy cane bagasse and nanocrystals (LCNCs) from bleached wood pulp were manufactured using microwave-assisted deep eutectic solvent (MV-DES, choline chloride and lactic acid) pretreatment combined with high-pressure homogenization (HPH). The resultant LCNFs and LCNCs showed fibril- and rod-like morphology with lignin content of 13.7 % and 5.9 %, respectively; and their suspensions exhibited the typical shear-thinning behaviors and gel-like viscoelastic properties. Benefited from the superior rheology of LCNMs and hydrogen bonding formed between LCNMs and GG, the presence of LCNMs significantly increased the zero-shear viscosity, yield stress, shear-thinning capacity as well as thermal stability of GG-VFFs. LCNM/GG-VFFs exhibited outstanding proppant-suspending capacity as demonstrated by sand particles being uniformly dispersed in the fluids without settling after standing for 24 h at 25 and 80 ℃.
To reconstruct the Holocene vegetation history from Liaohe Delta in northeast (NE) China, a high-resolution palynological study on a well-dated sediment core ZK2 was conducted. The pollen record of ZK2 suggests that during the early Holocene, the regional vegetation in the plain was meadow-dominated by Artemisia. And forest with cool-temperate conifers and temperate broad-leaved trees were present in the nearby hills, which is coincident with the gradual climate warming and delta transgression. From mid-Holocene to early late Holocene, meadow vegetation with Artemisia was relatively stable, while the forest vegetation with broadleaved trees reached the maximum expansion in the nearby hills. The large expansion of broadleaved trees indicates warm and humid regional environmental conditions and this is coincidental with the relatively high regional sea-level stand during this period. Since ca. 1470 cal yr BP, with the continuous delta progradation, a large coastal region was colonized by Suaeda spp., which suggests that the formation of unique red beach wetlands along the coastal region of the Liaohe Delta. By analysis of pollen dispersal and transportation mechanism in surface sediments of Liaodong Bay, it is indicated that the percentage changes of arboreal pollen dominated by Pinus and Quercus and the non-arboreal pollen dominated by Amaranthaceae and Artemisia in core ZK2 may as an index refers to the local sea level oscillation and paleoclimate change. Then by comparison with previous multi-proxy records together with the surface sediment record from Liaodong Bay, it is suggested that the Holocene vegetation changes of the Liaohe Delta are mainly driven by the intensity changes of East Asia monsoon and regional sea-level oscillation.
Application of bio-dyes, especially plant-based, is becoming increasingly popular in many industries such as textiles, food and pharmaceuticals. This trend could be explained by the ecological and durable nature of these compounds. The current paper aimed to investigate the microwave-assisted isolation of Alkannin dye from Alkanna tinctoria followed by the dyeing of bio-mordanted silk. For the purpose, acid solubilized, water solubilized, and acid-methanol solubilized extracts were obtained. Both respective extracts and silk fabrics were microwave irradiated for 2, 4 and 6 min. To ensure a green and clean dyeing process, bio-mordants were used. It is observed that acid solubilized extract applied at 55 °C for 55 min having 7 g/100 mL of NaCl salt as the exhausting agent has given extraordinary higher color strength (K/S) onto Microwave treatment (MW) treated silk fabric. Colorfastness tests using ISO-recommended requirements found that bio-mordants outperformed chemical mordants in terms of color depth and fastness. According to this study, it was proven that MW improved the dyeing performance of Alkannin in an acid-solubilized medium, where as in addition to the application of bio-mordants in comparison with sustainable chemical mordants have improved color characteristics of silk fabric dyed with Alkanna tinctoria extract.
In this study, we aimed to evaluate the properties and mechanisms of heavy metal adsorption by biochar derived from fallen leaves (FLB). The optimum manufacturing temperature of FLB for heavy metal removal was 650 °C, which resulted in a high carbon content and specific surface area. The maximum adsorption capacities of Cd and Pb by FLB650 were 86.2 and 135.1 mg/g, respectively; their adsorption was achieved via chemisorption. The results from chemisorption agreed with the Langmuir isotherm and pseudo-second order models. We confirmed that the adsorption of Pb by FBL was dominantly affected by the surface boundary layer; however, the adsorption of Cd occurred in cooperation with the boundary layer and pore diffusion; which was accomplished by employing the intraparticle diffusion model. After heavy metal adsorption, the distribution characteristics and mechanisms of each heavy metal in the FLB were noticeably observed through SEM-EDS, FTIR, and XRD. In addition, the content of exchangeable cations released from the FLB during the heavy metal adsorption process corresponded to 52% for Cd and 34% for Pb of the total amount of adsorbed heavy metals. We determined that FLB exhibits high affinity for heavy metals and its adsorption occurs via an adsorption mechanism based on the properties of FLB.
A matroid M is unbreakable if M is connected and, for each flat F, the matroid M/F is connected. Equivalently, M is unbreakable if its dual has no two skew circuits. This paper characterizes unbreakable matroids in terms of excluded parallel minors and determines all regular unbreakable matroids.
This paper depicts a simulation-based assessment of sediment quality on the performance of dedicated dredging projects for barrier island restoration in coastal Louisiana, USA. The research involved the development and integration of two sub-models. In the first, geomorphic modeling was used to simulate sediment transport dynamics within a proxy barrier island template over a 50-year trajectory. The template was assumed to be nourished with one of two sources of dredged material: nearshore (NS) sediments of lower quality (smaller grain diameter, higher organic fines); or higher quality sediments from distal sources located on the Outer Continental Shelf (OCS). In the second model, agency project records and commercial bids were used to estimate project construction costs as a function of dredge material quantity, transport distance, and project target elevation. These sub-models were coupled within a net present value framework from which average annual break-even values for ecosystem services (EBEV) were derived as an efficiency metric for comparing the economic performance of NS- and OCS-sourced projects. Results indicate that in some cases, the physical resiliency afforded by even small increases in sand diameter (+4 μm d50) can translate to greater long-term economic viability (lower EBEV) for OCS-sourced sediment transported over longer distances. Moreover, projects constructed with much higher diameter OCS sediment (+44 μm d50) with low fines and transported over relatively long distances (200 μm, 5% fines, 15–20 miles) were found to be more cost-effective than all comparably-sized projects constructed with lower quality NS sediments obtained from proximal sources (156 μm, 20% fines, 3–5 miles). For some comparisons, this quality advantage yielded a lower EBEV for OCS-sourced projects with transport distances exceeding 30 miles. Under storm-punctuated simulations, these quality advantages were more pronounced, with greater physical and economic implications for earlier (Y5) versus later (Y20) occurring storms. Budgeting for dedicated dredging projects has traditionally centered on the value of sediment as a commodity, with a focus on material placement cost. The findings of this study, however, indicate that a more comprehensive accounting of sediment quality and performance is required to maximize the economic efficiency of coastal restoration spending.
The classical additive Deligne–Simpson problem is the existence problem for Fuchsian connections with residues at the singular points in specified adjoint orbits. Crawley-Boevey found the solution in 2003 by reinterpreting the problem in terms of quiver varieties. A more general version of this problem, solved by Hiroe, allows additional unramified irregular singularities. We apply the theory of fundamental and regular strata due to Bremer and Sage to formulate a version of the Deligne–Simpson problem in which certain ramified singularities are allowed. These allowed singular points are called toral singularities; they are singularities whose leading term with respect to a lattice chain filtration is regular semisimple. We solve this problem in the special case of connections on Gm with a maximally ramified singularity at 0 and possibly an additional regular singular point at infinity. Examples of such connections arise from Airy, Bessel, and Kloosterman differential equations. They play an important role in recent work in the geometric Langlands program. We also give a complete characterization of all such connections which are rigid, under the additional hypothesis of unipotent monodromy at infinity.
The dispersal of larvae by ocean currents is likely to represent an increasingly important driver of marine population dynamics across fragmented habitats. A boost in availability of larval dispersal data from biophysical simulations has therefore led to routine calculations of population connectivity metrics that are used for area-based management decision support, including the placement of Marine Protected Areas (MPAs). However, connectivity-based decision support for area-based management is often complex, highly uncertain, and the associated conservation impact rarely if ever evaluated. In combination, these challenges risk stakeholder engagement, compliance, and overall management effectiveness. Here we use a case study representing multiple key fishery species on coral reefs in Indonesia to demonstrate that consideration of larval dispersal for MPA placement decision support could be critical to recover both fish populations and fisheries from depletion, thereby mitigating potentially severe impacts on coastal communities. Importantly, we further show that MPA placement decisions can be effective even if based on comparatively simple and empirically measurable dispersal characteristics. Maximizing larval export, expressed as the contribution of larvae from MPA candidate sites to total larval settlement in surrounding areas, for example, was found to be a broadly beneficial MPA placement prioritization approach. Across investigated fish families with diverse life histories, this strategy resulted in MPA network designs that increased catches by a factor of 1.3 ± 0.3 (mean ± SD) and total fish biomass by a factor of 3.2 ± 0.3 (9.7 ± 1.2 in no-fishing areas and 1.4 ± 0.3 in fished areas) compared to conditions without effectively managed or protected areas. Our findings are relevant for both the implementation and impact evaluation of global marine conservation policies, specifically in tropical biodiversity hotspots, such as Indonesia, where coral reefs are often overfished and increasingly threatened but local communities highly dependent on sustainable fisheries.
Corrosion effects on the shear behavior of friction connections are experimentally investigated in this paper. Based on ultrasonic technique, double lap friction connections were firstly assembled and accurate preloads were applied on high-strength bolts. Electrochemical accelerated corrosion method was employed to achieve four corrosion levels of specimens. Tensile test was then conducted on the corroded specimens and a finite element model was also established to make a comparison with test results. The study shows that net cross-section failure occurred for all the specimens and no obvious reduction of bearing capacity was found for corroded connections within 10% weight loss. Two slippages occurred during loading and finite element analysis shows that the second slip displacement is caused by slippage between washer and bolt head/nut. For friction connections with four corrosion levels, slip factors firstly increased and then gradually decreased with increase of the corrosion degree, and a prediction model of frictional resistance of the friction connection was proposed. Contact analysis of interfaces between plates accounts for the distribution of corrosion damage on the inner plates. Load-displacement curves obtained from finite element model agree well with test results. Corrosion effects on the bearing capacity of the friction connections were analyzed as ultimate load increases when slip factor or bolt preload increases.
Global deltas are facing severe challenges under the impacts of riverine sediment decline and large estuarine projects. Comparing with abundant research on the Yangtze subaqueous delta, the shoals in shallow waters are poorly understood. The Hengsha Shoal, Yangtze Delta, China, expands during the past ∼65 years, with only slight changes during the pre-projects period and remarkable variations in the projects period. It's now half-surrounded by the Hengsha Reclamation Project and the Deep Waterway Project, both facilitating the recent expansion. The current vertical net rate of change in the study area is −2.2 cm/yr, suggesting an overall balance between sediment deposition and erosion. Spatially, the Hengsha Shoal is currently changing from horizontal expansion to vertical accretion. Considering the spatial patterns of erosion/deposition and residual currents and sediment, modern geomorphic changes in the Hengsha Shoal appear to be dominated by internal sediment transport from deep to shallow waters. Considering further possible changing conditions, the future evolution of this shoal and the resulting potential ecological impacts should be studied further. This case study demonstrates that sediment dynamics in semi-artificial shoals can be totally different from the subaqueous delta, highlighting the importance of human engineering in governing large deltas globally.
This study aims at finding a set of optimum solutions of cutting conditions for the machining responses of cutting temperature and surface roughness in hard turning of 42CrMo4 alloy steel at high-pressure coolant (HPC) condition. Comparative experimental investigations between dry and HPC cutting environments were performed to evaluate the stated responses concerning the factors of cutting speed, feed, and work-piece hardness. The full factorial method was employed for the experimental design. The measured value of cutting temperature and surface roughness was found in a reduced amount for HPC condition compared to dry cut for all of the machining runs. Empirical models were developed by response surface methodology for the responses of HPC-assisted machining. The ANOVA result indicated that cutting speed and hardness has the greatest effect on cutting temperature and surface roughness, respectively. Design of experiment (DoE) based optimization was carried out that results in the best optimum settings of 147 m/min cutting speed, 0.12 mm/rev feed rate and 42HRC work-piece hardness. Genetic algorithm based multi-objective optimization was then performed that simultaneously minimizes both of the response models. Within the constraints of experimental design, the optimal set resulted at the range of 86–165 m/min cutting speed, 0.12–0.13 mm/rev feed rate and HRC 42–44 work-piece hardness.
Multiwavelets, which possess more favorable mathematical properties than scalar-wavelets, are deemed a promising means for non-stationary signal analysis. Due to high computational-complexity incurred in the construction of multiwavelets with arbitrary multiplicities (MWAM), the multiplicity of the multiwavelets currently utilized in practice is usually restricted to two, which limits the signal-processing performance. In this paper, a new fast MWAM construction method based on the finite-element analysis is introduced. The four orthogonality equations for solving the filter-coefficient matrices in the construction of multiwavelet functions are simplified to two equations mathematically, so the computational-complexity of the MWAM construction is significantly reduced. Meanwhile, a new optimal multiplicity selection strategy is also proposed based on the comparison between the time-frequency bandwidth-products of the multiscaling function and the probed signal. Finally, our proposed new fast MWAM-construction method in tandem with the new multiplicity-determination scheme is tested by an application, namely mechanical-bearing fault-diagnosis. The corresponding performance is quite promising. Our proposed new MWAM construction method along with the associated multiplicity-determination scheme can be applicable for many time-frequency signal-approximation and feature-extraction applications.
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9,220 members
Aly Mousaad Aly
  • Department of Civil and Environmental Engineering
Jan M. Hondzinski
  • School of Kinesiology
George Strain
  • Department of Comparative Biomedical Sciences
Marc Dalecki
  • School of Kinesiology
Michelle L. Osborn
  • Department of Comparative Biomedical Sciences
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70803, Baton Rouge, LA, United States
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William L. Jenkins
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http://www.lsu.edu/