Nueta Hidatsa Sahnish College

Amelanchier alnifolia Nutt. (Juneberry) is a native North American fruit that has gained increasing interest for its horticultural potential and presumed food values. Despite this growing interest, comprehensive nutritional and phytochemical characterization of Juneberry cultivars remains limited. This study describes the development of a high-performance liquid chromatography (HPLC) method for the extraction and quantification of phenolic compounds and carbohydrates within freeze-dried A . alnifolia samples. The phenolic compounds were extracted from the samples using a 1:1 methanol to water solution. The extract was then analyzed on a C30 reverse-phase column with a C18 guard column under gradient elution with HPLC-grade aqueous 5% o-phosphoric acid and methanol as the mobile phase. Both hydroxycinnamic acids and hydroxybenzoic acids, subclasses of phenolic acids, were analyzed using PDA detection at 310 nm and 215 nm, respectively. The soluble sugars, glucose and fructose as well as the soluble sugar alcohol sorbitol were extracted using HPLC-grade water and separated via a Ca 2+ monosaccharide column under isocratic conditions. Detection was performed by a refractive index detector (RID). This method provides a way to reproduce chromatographic separation, extraction, and quantification of high enough quality for comparative biochemical characterization of juneberry cultivars that can be applied to a broad range of fruits rich in phenolic compounds.

This paper is a "Work-in-Progress". This paper describes the synergetic intersection of two programs designed to bring a particular group of minority students into aspects of a STEM career field. One program, sponsored by a national laboratory is designed to inform and train a these students about advanced manufacturing methods, in this case 3-D printing. The other program is also aimed at that same group of minority students but the purpose of the second program is to aid the students in becoming baccalaureate engineers. The programs exist simultaneously at a small group of tribal colleges or universities, TCU's in the north-central US. The key question to be answered here is how can cooperation between the two programs resulted in a net positive impact to the surrounding community. A brief historical summary of similar programs trying to attract student talent into similar but different career fields will be given, i.e. in-home health services versus nursing or. MD programs, computer technician versus computer program. Some of the prior problems could be attributed to limited available human talent and a lack of program cooperation. A short description of each program will be given highlighting similarities and differences and the resources needed by each. The advantages of working the programs in tandem in particular areas will be discussed and examples given. Potential future opportunities and directions provided to each student by conducting the programs in cooperation will be illustrated. It is believed that combining such programs, experiences that allow students to have some immersive time within different career paths, will provide them with the opportunity to evaluate their own reaction and suitability to each career path, allowing them to envision themselves in those areas. This should provide for a more informed career choice and other benefits. Identifying how this cooperation might impact first year engineering students, leading to better persistence in the curriculum, is a major goal of this work.

Biopolymers are of huge interest as they carry potential to minimize the environmental hazards caused by synthetic materials. Poly(lactic acid) (PLA) reinforced by cellulose nanocrystals (CNCs) has shown promising results. To obtain the optimum characteristics of PLA-CNC nanocomposites, a superior compatibility between PLA and CNCs is paramount. The application of chemical surface modification technique is an essential step to improve the interaction between hydrophilic CNCs and hydrophobic PLA. In this study, a time-efficient esterification technique using valeric acid was introduced to improve the compatibility between CNCs and PLA. Masterbatches were prepared using spin-coating method to ensure the maximum dispersion of CNCs through PLA and to decrease the drying time. Nanocomposites were prepared using extrusion and injection molding. The degree of substitution for modified CNCs was calculated as 0.35. Transmission electron microscopy exhibited esterified CNCs (e-CNCs) in the nanoscale with rod shape structure. Thermal stability improved by 15% in nanocomposites containing 3% e-CNCs, whereas untreated CNCs didn’t alter the thermal stability to a notable extent. A substantial increase of 200% was observed in crystallinity of nanocomposites reinforced with 3% e-CNCs. The incorporation of CNCs into PLA resulted in an increase in storage modulus and a decrease in tan δ intensity which was more profound in PLA-e-CNCs. The tensile strength of PLA-e-CNCs composites was found to be superior to composites reinforced with untreated CNCs. The results confirmed that a combination of time-efficient esterification and spin-coated masterbatch was a successful approach to uniformly disperse CNCs in PLA matrix.

Composites of Poly(lactic acid) (PLA) and spherical zinc oxide (ZnO) nanoparticles were prepared using melt processing followed by injection molding. The effect of nanosized ZnO on the molecular structure, thermal properties, dynamic mechanical properties, and flow characteristics of PLA composites were analyzed. Scanning electron microscopy images illustrated the formation of ZnO aggregates through PLA matrix. The molecular weight of PLA‐ZnO experienced a substantial decline by 55%, suggesting the presence of ZnO provoked degradation of PLA during composite preparation. Glass transition temperature of PLA‐ZnO decreased by 18% as compared with pure PLA, confirming the deleterious role of ZnO in PLA. The ZnO nanoparticles acted as a reactant and increased the thermal degradation rate. However, the incorporation of ZnO into PLA increased the crystallinity up to 20% and the storage modulus of composites in glassy state by 10%. The higher peak value of tan δ in composites suggested the more viscous behavior, which was further supported by lower number average molecular weight. The complex viscosity of composites exhibited a large Newtonian region over low shear rate, followed by shear thinning phenomenon. A significant decrease (96%) in complex viscosity was observed with the addition of ZnO into PLA. POLYM. ENG. SCI., 59:1242–1249 2019. © 2019 Society of Plastics Engineers

We use deep Herschel PACS and SPIRE observations in GOODSS, GOODSN and COSMOS to estimate the average dust mass (Mdust) of galaxies on a redshift-stellar mass (Mstar)-SFR grid. We study the scaling relations between Mdust, Mstar and SFR at z<=2.5. No clear evolution of Mdust is observed at fixed SFR and Mstar. We find a tight correlation between SFR and Mdust, likely a consequence of the Schmidt-Kennicutt (S-K) law. The Mstar-Mdust correlation observed by previous works flattens or sometimes disappears when fixing the SFR. Most of it likely derives from the combination of the Mdust-SFR and Mstar-SFR correlations. We then investigate the gas content as inferred by converting Mdust by assuming that the dust/gas ratio scales linearly with the gas metallicity. All galaxies in the sample follow, within uncertainties, the same SFR-Mgas relation (integrated S-K law), which broadly agrees with CO-based results for the bulk of the population, despite the completely different approaches. The majority of galaxies at z 2 form stars with an efficiency (SFE=SFR/Mgas) 5 times higher than at z 0. It is not clear what fraction of such variation is an intrinsic redshift evolution and what fraction arises from selection effects. The gas fraction (fgas) decreases with Mstar and increases with SFR, and does not evolve with z at fixed Mstar and SFR. We explain these trends by introducing a universal relation between fgas, Mstar and SFR, non-evolving out to z 2.5. Galaxies move across this relation as their gas content evolves in time. We use the 3D fundamental fgas-Mstar-SFR relation and the redshift evolution of the Main Sequence to estimate the evolution of fgas in the average population of galaxies as a function of z and Mstar, and we find evidence a downsizing scenario.