Vegetation Analysis of Urban Ethnic Markets Shows Supermarket Generalists and Chinatown Ethnic-specialist Vendors

researchThe growing cultural diversity in the United States calls attention to ethnobotanical studies of urban ethnic food markets. These venues illustrate dynamic interactions between people and plants. A market survey of the Chinatown markets in Honolulu, Hawai`i was conducted to collect empirical data on this culturally rich urban area. The objectives included: (1) To analyze the food plant richness of selected Chinatown markets in comparison to local mainstream supermarkets; and (2) To test the use of vegetation analysis to describe the structure of these markets (e.g., “ethnic markets”). Surveys and mapping of food plants at three market areas in Chinatown and three mainstream supermarkets were conducted between February and March 2006. Microsoft Excel and the Community Analysis Package programs were used to analyze and compare plant richness and the structure of vendors and markets. In all of the markets combined, 291 “fresh” food plant varieties were recorded, representing 42 plant families and a group of fungi. The mainstream supermarkets were more rich in varieties of food plants than the Chinatown market area (mean ± s, 144 ± 21 vs. 95 ± 23, p=0.05, Mann-Whitney U test). Allium cepa L. and Allium sativum L. were ubiquitous. The Mainstream market group contained significantly more sweet-fruits than the Chinatown market areas. Agglomerate cluster analyses revealed groupings of mainstream supermarkets, Chinatown market areas; further analysis of the Chinatown areas defined culturally identified “Filipino,” “Vietnamese,” and specialty fruits vendors. Mainstream supermarkets may be viewed as “generalists” while the Chinatown market areas and vendors may be viewed as “specialists” for an ethnic or cultural group or food plant commodity

Infrared and Raman spectra of LiV2O5 single crystals

The phonon dynamics of LiV2O5 single crystals is studied using infrared and Raman spectroscopy techniques. The infrared-active phonon frequencies and dielectric constants are obtained by oscillator fitting procedure of the reflectivity data measured at room temperature. The Raman scattering spectra are measured at room temperature and at T=10 K in all nonequivalent polarized configurations. The assignment of the phonons is done by comparing the infrared and Raman spectra of LiV2O5 and NaV2O5. The factor-group-analysis of the LiV2O5 crystal symmetry and of its constituent layers is performed to explain the symmetry properties of the observed modes. We concluded that layer symmetry dominates in the vibrational properties of this compound.Comment: 10 pages, 5 figure

Isotropic Conductivity of Two-Dimensional Three-Component Symmetric Composites

The effective dc-conductivity problem of isotropic, two-dimensional (2D), three-component, symmetric, regular composites is considered. A simple cubic equation with one free parameter for $\sigma_{e}(\sigma_1,\sigma_2,\sigma_3)$ is suggested whose solutions automatically have all the exactly known properties of that function. Numerical calculations on four different symmetric, isotropic, 2D, three-component, regular structures show a non-universal behavior of $\sigma_{e}(\sigma_1,\sigma_2,\sigma_3)$ with an essential dependence on micro-structural details, in contrast with the analogous two-component problem. The applicability of the cubic equation to these structures is discussed. An extension of that equation to the description of other types of 2D three-component structures is suggested, including the case of random structures. Pacs: 72.15.Eb, 72.80.Tm, 61.50.AhComment: 8 pages (two columns), 8 figures. J. Phys. A - submitte

Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics

Molybdenum disulfide (MoS2), a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia

Anomalous Lattice Vibrations of Single and Few-Layer MoS2

Molybdenum disulfide (MoS2) of single and few-layer thickness was exfoliated on SiO2/Si substrate and characterized by Raman spectroscopy. The number of S-Mo-S layers of the samples was independently determined by contact-mode atomic-force microscopy. Two Raman modes, E12g and A1g, exhibited sensitive thickness dependence, with the frequency of the former decreasing and that of the latter increasing with thickness. The results provide a convenient and reliable means for determining layer thickness with atomic-level precision. The opposite direction of the frequency shifts, which cannot be explained solely by van der Waals interlayer coupling, is attributed to Coulombic interactions and possible stacking-induced changes of the intralayer bonding. This work exemplifies the evolution of structural parameters in layered materials in changing from the 3-dimensional to the 2-dimensional regime.Comment: 14 pages, 4 figure

Mechanical and Electronic Properties of MoS2_2 Nanoribbons and Their Defects

We present our study on atomic, electronic, magnetic and phonon properties of one dimensional honeycomb structure of molybdenum disulfide (MoS$_2$) using first-principles plane wave method. Calculated phonon frequencies of bare armchair nanoribbon reveal the fourth acoustic branch and indicate the stability. Force constant and in-plane stiffness calculated in the harmonic elastic deformation range signify that the MoS$_2$ nanoribbons are stiff quasi one dimensional structures, but not as strong as graphene and BN nanoribbons. Bare MoS$_2$ armchair nanoribbons are nonmagnetic, direct band gap semiconductors. Bare zigzag MoS$_2$ nanoribbons become half-metallic as a result of the (2x1) reconstruction of edge atoms and are semiconductor for minority spins, but metallic for the majority spins. Their magnetic moments and spin-polarizations at the Fermi level are reduced as a result of the passivation of edge atoms by hydrogen. The functionalization of MoS$_2$ nanoribbons by adatom adsorption and vacancy defect creation are also studied. The nonmagnetic armchair nanoribbons attain net magnetic moment depending on where the foreign atoms are adsorbed and what kind of vacancy defect is created. The magnetization of zigzag nanoribbons due to the edge states is suppressed in the presence of vacancy defects.Comment: 11 pages, 5 figures, first submitted at November 23th, 200

Effective mechanical properties of multilayer nano-heterostructures

Two-dimensional and quasi-two-dimensional materials are important nanostructures because of their exciting electronic, optical, thermal, chemical and mechanical properties. However, a single-layer nanomaterial may not possess a particular property adequately, or multiple desired properties simultaneously. Recently a new trend has emerged to develop nano-heterostructures by assembling multiple monolayers of different nanostructures to achieve various tunable desired properties simultaneously. For example, transition metal dichalcogenides such as MoS2 show promising electronic and piezoelectric properties, but their low mechanical strength is a constraint for practical applications. This barrier can be mitigated by considering graphene-MoS2 heterostructure, as graphene possesses strong mechanical properties. We have developed efficient closed-form expressions for the equivalent elastic properties of such multi-layer hexagonal nano-hetrostructures. Based on these physics-based analytical formulae, mechanical properties are investigated for different heterostructures such as graphene-MoS2, graphene-hBN, graphene-stanene and stanene-MoS2. The proposed formulae will enable efficient characterization of mechanical properties in developing a wide range of application-specific nano-heterostructures

Market Survey Research: A model for ethnobotanical education

educationEthnobiological imperatives in education and NSF initiatives for improving excellence in science, technology, engineering and mathematics (STEM) education for all students were addressed by the development of a research oriented, market survey ethnobotanical project developed with the involvement of undergraduate students. This market survey project presents a model for Ethnobiological and STEM education that is adaptable to educational institutions and communities world-wide. Collaboration among users of the model and synthesis of results would provide an international look at the biocomplexity of markets systems. Students gained experience in scientific research, including: observation and forming hypothesis, collection and analysis of data, and dissemination of results. Students practiced ethnobotanical research skills, including: developing and applying an informed consent statement, producing herbarium vouchers, interacting with cultural representatives. Survey materials and hypotheses were modified during the research period to maximize our efforts. Students co-authored with instructor two publications resulting from the research involvement. The instructor gained experience by involving students in research and application of the instructor’s research to an undergraduate ethnobotanical project. Challenges are discussed, as well as recommendations synthesized from these experiences and from reviews of other student-research studies