Thermophysical analysis of SU8‐modified microstructures created by visible light lithography

SU8 has been modified with photoinitiators Rose Bengal, H‐NU 470 and H‐NU 535, to conduct visible light lithography. The thermophysical properties of the lithographically transformed modified SU8 photoresins were investigated. The influence of the concentration of visible light photosensitizer and photoinitiator as well as exposure time to visible laser on thermal stability and curing kinetics were analyzed. Significant differences in the thermophysical properties were observed in these three photoinitiator groups of modified SU8 photoresins. These results provide with usable quantitative information regarding resin formulation to optimize lithography processing parameters, and therefore, the ultimate properties of lithographically formed microstructures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 47–54, 2010     

1,3-Dipolar cycloaddition of 1H-pyrazinium-3-olate and N1- and C-methyl substituted pyrazinium-3-olates with methyl acrylate: a density functional theory study

A DFT study of the 1,3-dipolar cycloaddition of methyl acrylate to 1H-pyrazinium-3-olate and N1- and C-methyl substituted pyrazinium-3-olates, in the gas phase and in THF, has been carried out at the B3LYP/6-31G(d) level. Two stereoisomeric pathways, endo and exo, and two regioisomeric channels, 2-oxo-3,8-diazabicyclo[3.2.1]octane-6-ester and 7-ester products, have been considered. Thermodynamic and kinetic parameters calculated at room temperature have been analyzed. The regioselectivity has been interpreted using reactivity indices. It is generally found that the exo pathway is preferred and the formation of the 6-esters is dominant. The theoretical data obtained for the cycloaddition reaction of 1,5-dimethylpyrazinium-3-olate with methyl acrylate are consistent with the literature where the 6-exo regioisomer is formed as the major cycloadduct.     

An Alternative Approach to the Electric Charge Quantization with Non-global Potentials

We present an alternative approach to justify the electric charge quantization by means of non-global electromagnetic potentials. We adopt a non-global potential whose singularity does not goes over to infinity and can be entirely embedded into an arbitrarily small closed ball.     

Electrolytic synthesis of chloroacetic acids in a filter-press reactor from polychloromethanes

Electrochemical carboxylation of carbon tetrachloride and chloroform to synthesize chloroacetic acids in mild conditions has been investigated by galvanostatic electrolyses using a homemade electrochemical filter-press reactor. Undivided filter-press reactor consisting of a planar Zn cathode and a planar Al sacrificial anode has been shown to be an optimal electrochemical device for the electrocarboxylation reaction. The influence of some operative parameters, such as current density and concentration of supporting electrolyte, on the efficiency and selectivity of the synthetic process has been investigated. Highly current efficiencies and target products yields (both of them > 85%) were achieved in all cases, whereas byproducts formation was minimal.     

Melatonin in Brassicaceae: Role in Postharvest and Interesting Phytochemicals

Brassicaceae plants are of great interest for human consumption due to their wide variety and nutritional qualities. Of the more than 4000 species that make up this family, about a hundred varieties of 6–8 genera are extensively cultivated. One of the most interesting aspects is its high content of glucosinolates, which are plant secondary metabolites with widely demonstrated anti-oncogenic properties that make them healthy. The most relevant Brassicaceae studies related to food and melatonin are examined in this paper. The role of melatonin as a beneficial agent in seedling grown mainly in cabbage and rapeseed and in the postharvest preservation of broccoli is especially analyzed. The beneficial effect of melatonin treatments on the organoleptic properties of these commonly consumed vegetables can be of great interest in the agri-food industry. Melatonin application extends the shelf life of fresh-cut broccoli while maintaining optimal visual and nutritional parameters. In addition, an integrated model indicating the role of melatonin on the organoleptic properties, the biosynthesis of glucosinolates and the regulatory action of these health-relevant compounds with anti-oncogenic activity is presented.     

Functionalization of Rhodamine Platforms with 3-Hydroxy-4-pyridinone Chelating Units and Its Fluorescence Behavior towards Fe(III)

Functionalization of xanthene fluorophores with specific receptor units is an important topic of research aiming for the development of new analytical tools for biological sciences, clinical diagnosis, food and environmental monitoring. Herein, we report a new dihydrorosamine containing two active amino groups, which was functionalized with 3-benzyloxy-1-(3′-carboxypropyl)-2-methyl-4-pyridinone through an amide coupling strategy. Benzylated mono- and di-functionalized dihydrorosamine derivatives (H in position 9 of the xanthene) were obtained, but with modest reaction yields, requiring long and laborious purification procedures. Looking for a more efficient approach, rhodamine 110 was selected to react with the carboxypropyl pyridinone, enabling the isolation of the corresponding mono- and di-functionalized derivatives in amounts that depend on the excess of pyridinone added to the reaction. The structure of all compounds was established by ¹H and ¹³C NMR, MS (ESI) and their absorption and emission properties were evaluated in dichloromethane. The fluorescence behavior of the debenzylated mono-rhodamine 110 derivative in the presence of Fe(III) was studied, making it an interesting fluorogenic dye for future optical sensing applications.     

Vibrational spectra of cyclic C8 in solid argon

Vapors from solid and powdered carbon, emitted from an oven cycled between 2000 and 3000 K, were co-condensed with argon onto a CsI substrate maintained at 10 K. The cycling process produced a multilayered matrix with regions of high carbon density alternating with layers of argon. FTIR measurements including ¹³C isotopic data, supported by ab initio calculations, allow the assignment of a band observed at 1817.8 cm⁻¹ to the ν₁₂(e_u) fundamental of cyclic C₈.     

Harmonic mappings of Kähler manifolds to locally symmetric spaces

Research partially supported by the National Science Foundation.