North Carolina State UniversityRaleigh

Charleston, United States

North Carolina State UniversityRaleigh

Charleston, United States

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Deng J.,North Carolina State UniversityRaleigh | Dong J.,North Carolina State UniversityRaleigh | Cohen P.,North Carolina State UniversityRaleigh
Procedia Manufacturing | Year: 2016

This paper introduces a high precision 3D nanofabrication approach using ultrasonic vibration assisted nanomachining using an AFM operating in constant height control mode. Nanostructures with 3D features were successfully fabricated on PMMA film with the feature height manipulated through controlling the absolute heights of z-scanner in AFM. Two methods were used to move the AFM tip to create desire features, vector mode and raster scan mode. Relatively simple features, such as stair-like nanostructure with five steps was successfully fabricated in vector mode. Complex nanostructure with discrete height levels and continuous changes were successfully fabricated in raster scan mode. By carefully selecting the machining parameters, the feature dimension and height can be precisely controlled with only small variation from the designed value. Moreover, this paper explores the capability of transferring 3D nanostructures from PMMA film onto silicon substrate. After calibrating the recipe of Reactive Ion Etching (RIE) process, 3D nanostructures are successfully transferred to silicon wafer with controllable selectivity between PMMA and silicon. The results of fabricating 3D structures on silicon substrates show promising potential of many applications, such as mold preparation in nanoimprint lithography. © 2016 The Authors


Osburn C.L.,North Carolina State UniversityRaleigh
Limnology and Oceanography | Year: 2016

We assessed which factors control summer epilimnion thickness in arctic lakes of southwest Greenland. A suite of 22 lakes that thermally stratify was measured in the summer of 2013; a sub-set of eight of the lakes was measured again in 2014, which was a warmer summer than 2013. Regression analysis of the 22 lakes indicated that the 1% attenuation depth for photosynthetically active radiation (PAR) was the strongest single predictor (R2=0.75) of epilimnion thickness across lakes; the addition of epilimnion temperature to the PAR model explained additional variability (R2=0.79). The importance of including temperature in the model was apparent in the results of model validation as well as when comparing across years: while the 1% PAR was 0.4-2 m deeper in 2014 compared with 2013, water temperatures were 2-3°C higher, resulting in July epilimnion thicknesses that were equal to or shallower than in 2013. In these lakes with low color dissolved organic carbon (DOC), multiple factors control the 1% PAR, including absorbance at 440 nm (a440), 380 nm (a380), and 320 (a320), chlorophyll a (Chl a) and DOC concentration. In 2014, when 1% PAR was deeper than in 2013, a380, Chl a and DOC were lower in six of the eight lakes. Our results reveal that the thermal structure of these arctic lakes is under complex control by air temperatures and factors that affect PAR attenuation, particularly Chl a and DOC quality, suggesting that continued warming in the Arctic will have strong effects on lake stratification. © 2016 Association for the Sciences of Limnology and Oceanography.


Yi E.,Korea University | Shamey R.,North Carolina State UniversityRaleigh
Color Research and Application | Year: 2015

This crosscultural study was aimed at correlating color emotions and preference for persimmon-dyed cotton fabrics known as Galchon. Cotton fabrics were dyed with persimmon powder, in a range of shades, and in some cases were also iron mordanted. Textile and fashion students from Jeju National University in Korea and North Carolina State University (NCSU) in USA participated in the visual assessment of dyed samples and were asked to scale their visual experience and state their emotion and preference for the terms "Bright," "Heavy," "Soft," "Strong," "Deep," and "Like." Korean observers used "Strong" for iron-mordanted Galchon, and American observers did not associate "Bright" or "Deep" with weakly dyed fabrics. In addition to the subjective terms described, the color preference for samples was quantified using their CIE colorimetric attributes. For Korean observers, the results indicate a correlation between L>* and "Bright," whereas for Americans a stronger correlation was obtained against "Soft." American observers' results also show a relationship between C* and the term "Warm," especially for dyeings of Galchon at high concentrations. It was also found that iron mordanting affected responses from both groups but only influenced the color preference of Korean observers. © 2015 Wiley Periodicals, Inc.


Li W.,North Carolina State UniversityRaleigh | Sankarasubramanian A.,North Carolina State UniversityRaleigh | Ranjithan R.S.,North Carolina State UniversityRaleigh | Brill E.D.,North Carolina State UniversityRaleigh
Water Resources Research | Year: 2014

Regional water supply systems undergo surplus and deficit conditions due to differences in inflow characteristics as well as due to their seasonal demand patterns. This study proposes a framework for regional water management by proposing an interbasin transfer (IBT) model that uses climate-information-based inflow forecast for minimizing the deviations from the end-of-season target storage across the participating pools. Using the ensemble streamflow forecast, the IBT water allocation model was applied for two reservoir systems in the North Carolina Triangle Area. Results show that interbasin transfers initiated by the ensemble streamflow forecast could potentially improve the overall water supply reliability as the demand continues to grow in the Triangle Area. To further understand the utility of climate forecasts in facilitating IBT under different spatial correlation structures between inflows and between the initial storages of the two systems, a synthetic experiment was designed to evaluate the framework under inflow forecast having different skills. Findings from the synthetic study can be summarized as follows: (a) inflow forecasts combined with the proposed IBT optimization model provide improved allocation in comparison to the allocations obtained under the no-transfer scenario as well as under transfers obtained with climatology; (b) spatial correlations between inflows and between initial storages among participating reservoirs could also influence the potential benefits that could be achieved through IBT; (c) IBT is particularly beneficial for systems that experience low correlations between inflows or between initial storages or on both attributes of the regional water supply system. © 2014. American Geophysical Union.


PubMed | North Carolina State UniversityRaleigh
Type: | Journal: Frontiers in microbiology | Year: 2016

Bifidobacteria are important members of the human gastrointestinal tract that promote the establishment of a healthy microbial consortium in the gut of infants. Recent studies have established that the Bifidobacterium genus is a polymorphic phylogenetic clade, which encompasses a diversity of species and subspecies that encode a broad range of proteins implicated in complex and non-digestible carbohydrate uptake and catabolism, ranging from human breast milk oligosaccharides, to plant fibers. Recent genomic studies have created a need to properly place Bifidobacterium species in a phylogenetic tree. Current approaches, based on core-genome analyses come at the cost of intensive sequencing and demanding analytical processes. Here, we propose a typing method based on sequences of glycolysis genes and the proteins they encode, to provide insights into diversity, typing, and phylogeny in this complex and broad genus. We show that glycolysis genes occur broadly in these genomes, to encode the machinery necessary for the biochemical spine of the cell, and provide a robust phylogenetic marker. Furthermore, glycolytic sequences-based trees are congruent with both the classical 16S rRNA phylogeny, and core genome-based strain clustering. Furthermore, these glycolysis markers can also be used to provide insights into the adaptive evolution of this genus, especially with regards to trends toward a high GC content. This streamlined method may open new avenues for phylogenetic studies on a broad scale, given the widespread occurrence of the glycolysis pathway in bacteria, and the diversity of the sequences they encode.

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