Regional economics in its 1950s: recent theoretical directions and future challenges

Regional economics has just entered in its 1950s. It is a young discipline compared to other branches of the economy, yet much work has been done in this field. A vast and rich number of theoretical and methodological approaches exists nowadays to incorporate space into logical schemes, laws and models which regulate and interpret the formation of prices, demand, productive capacity, levels of output and development, growth rates, and the distribution of income in conditions of unequal regional endowments of resources. This contribution provides the state of the art in Regional Economics with the aim to highlight the scientific achievements obtained so far and the theoretical and methodological gaps which still need to be filled out. Aspects that run counter to general beliefs emerge by reading the original contributions of wellknown theoreticians, and will be presented. Future challenges will emerge from a critical approach to the milestones achieved so far. This paper is at the basis of a keynote lecture given at the 46° ERSA Conference, held in Volos, 30 August–3 September 2006.     

Zinc porphyrin-driven assembly of gold nanofingers

Nanofingers of gold covered by porphyrins are prepared by a combination of atomic manipulation and surface self-organization. A submonolayer of zinc(II) 5,10,15,20-tetrakis(4-tert-butylphenyl)-porphyrin (ZnTBPP) axially ligated to a self-assembled monolayer of 4-aminothiophenol (4-ATP) on Au(111) is prepared and studied using a combination of ultrahigh vacuum techniques. Under the electric field produced by the STM tip, the relatively weakly bound Au surface atoms along the discommensuration lines become mobile due to the strong bond to 4-ATP, while the tendency of the porphyrins towards self-assembly result in a collective motion of gold clusters. The clusters diffuse onto the surface following well-defined pathways along the [112] direction and then reach the step edges where they assembled, thus forming nanofingers. First-principles density functional theory calculations demonstrate the reduction of the binding energies between the surface gold clusters and the substrate induced by adsorption of thiols. Scanning tunneling microscopy images show assemblies across three adjacent discommensuration lines of the Au(111)-(22 x square root 3) reconstruction, which collectively diffuse along these lines to form islands nucleated at step edges.     

The behavior of dithiocarbimate derivative as safety accelerator of natural rubber compounds

A conventional vulcanization system containing tetrabutylammonium bis(4‐methylphenyldithiocarbimato)zincate(II) (ZNIBU) was used for curing of natural rubber (NR) compounds. Rheometric (t_s1, t₉₀, and CRI) and mechanical properties, such as tensile and tear strengths and modulus at 300%, were measured to evaluate the acceleration potential of ZNIBU. Commercial accelerators (TMTD, MBTS, and CBS) and a binary system CBS/ZNIBU were also tested for comparison purposes. It was observed that ZNIBU alone does not give either safe scorch time or cure rates appropriate for industrial applications. Nevertheless, mechanical properties are comparable to those given by the other accelerators used. As for the binary system, positive synergistic effects can be found in tear strength and modulus of NR vulcanizates. Besides, ZNIBU does not contribute for the formation of nitrosamines in the vulcanization process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymer electrolytes for dye-sensitized solar cells prepared by photopolymerization of PEG-based oligomers

We report on the preparation and characterization of novel polymer electrolyte membranes for quasi-solid dye-sensitized solar cells. New methacrylic–acrylic gel-polymer electrolytes were prepared by photo-polymerization of mono/di-functional monomers. The crosslinked films were self standing, transparent and flexible. They were swelled by an iodine–iodide solution, obtaining a stable gel, where the polymeric network acts as a cage to retain the liquid, preventing its evaporation. Such a system combines the cohesive property of a solid with the high ionic conductivity of a liquid. The evaluation of the structural and physical-chemical characteristics of the polymer, combined with the electrical characterization of the membranes by means of the electrochemical impedance spectroscopy, allowed us to investigate the structure/property relationship of the material. The electric characterizations of the solar harvester based on the gel-polymer electrolyte showed a maximum photovoltaic conversion efficiency of 4.41%. Moreover, a significant improvement in the durability of the device was demonstrated with respect to the liquid electrolyte-based counterpart.     

Purification and characterization of an extracellular trypsin-like protease of Fusarium oxysporum var. lini

An alkaline serineprotease, capable of hydrolyzing Nalpha-benzoyl- dl arginine p-nitroanilide, was secreted by Fusarium oxysporum var. lini grown in the presence of gelatin as the sole nitrogen and carbon source. The protease was purified 65-fold to electrophoretic homogenity from the culture supernatant in a three-step procedure comprising QSepharose chromatography, affinity chromatography, and FPLC on a MonoQ column. SDS-PAGE analysis of the purified protein indicated an estimated molecular mass of 41 kDa. The protease had optimum activity at a reaction temperature of 45 degrees C and showed a rapid decrease of activity at 48 degrees C. The optimum pH was around 8.0. Characterization of the protease showed that Ca2+ and Mg2+ cations increased the activity, which was not inhibited by EDTA or 1,10-phenanthroline. The enzyme activity on Nalpha-benzoyl-DL arginine p-nitroanilide was inhibited by 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride, p-aminobenzamidine dihydrochloride, aprotinin, 3-4 dichloroisocoumarin, and N-tosyl-L-lysine chloromethyl ketone. The enzyme is also inhibited by substrate concentrations higher than 2.5 x 10(-4)M. The protease had a Michaelis-Menten constant of 0.16 mM and a V(max) of 0.60 mumol released product.min(-1).mg(-1) enzyme when assayed in a non-inhibiting substrate concentration. The activity on Nalpha-benzoyl- dl arginine p-nitroanilide was competitively inhibited by p-aminobenzamidine dihydrochoride. A K(i) value of 0.04 mM was obtained.     

Cytotoxic effects of thiamethoxam in the midgut and malpighian tubules of Africanized Apis mellifera (Hymenoptera: Apidae)

Due to its expansion, agriculture has become increasingly dependent on the use of pesticides. However, the indiscriminate use of insecticides has had additional effects on the environment. These products have a broad spectrum of action, and therefore the insecticide affects not only the pests but also non‐target insects such as bees, which are important pollinators of agricultural crops and natural environments. Among the most used pesticides, the neonicotinoids are particularly harmful. One of the neonicotinoids of specific concern is thiamethoxam, which is used on a wide variety of crops and is toxic to bees. Thus, this study aimed to analyze the effects of this insecticide in the midgut and Malpighian tubule cells of Africanized Apis mellifera. Newly emerged workers were exposed until 8 days to a diet containing a sublethal dose of thiamethoxam equal to 1/10 of LC₅₀ (0.0428 ng a.i./l L of diet). The bees were dissected and the organs were processed for transmission electron microscopy. The results showed that thiamethoxam is cytotoxic to midgut and Malpighian tubules. In the midgut, the damage was more evident in bees exposed to the insecticide on the first day. On the eighth day, the cells were ultrastructurally intact suggesting a recovery of this organ. The Malpighian tubules showed pronounced alterations on the eighth day of exposure of bees to the insecticide. This study demonstrates that the continuous exposure to a sublethal dose of thiamethoxam can impair organs that are used during the metabolism of the insecticide. Microsc. Res. Tech. 77:274–281, 2014. © 2014 Wiley Periodicals, Inc.     

Classification of Brazilian honeys by physical and chemical analytical methods and low field nuclear magnetic resonance (LF H NMR)

This study evaluated the possibility of differentiating the botanical origin of honeys using Low Field Nuclear Magnetic Resonance (LF ¹H NMR). Eighty samples of honey from 8 different botanical sources (eucalyptus, “assa-lipto”, oranges, Barbados cherry, cashew tree, “assa-peixe”, “cipó-uva” and polyfloral) were analyzed. A close correlation (p < 0.01) was established between the LF ¹H NMR analysis and physical and chemical measurements, including water content, water activity, pH and color. Bi-exponential fitting of the transverse relaxation (T₂) data revealed two water populations in all samples, T₂₁ and T₂₂, corresponding to relaxation times of 0.6–1.8 ms and 2.3–5.4 ms respectively. The observed differences in the relaxation times suggest that these were influenced by the differences in botanical origins. Good linear correlations were observed between the T₂ and T₂₁ parameters and the physical and chemical data. This study demonstrated that LF ¹H NMR can be a viable technique for use in classifying honeys by their botanical origin.     

Consumer food safety knowledge, practices, and demographic differences: findings from a meta-analysis

Risk communication and consumer education to promote safer handling of food can be the best way of managing the risk of foodborne illness at the consumer end of the food chain. Thus, an understanding of the overall status of food handling knowledge and practices is needed. Although traditional qualitative reviews can be used for combining information from several studies on specific food handling behaviors, a structured approach of meta-analysis can be more advantageous in a holistic assessment. We combined findings from 20 studies using meta-analysis methods to estimate percentages of consumers engaging in risky behaviors, such as consumption of raw food, poor hygiene, and cross-contamination, separated by various demographic categories. We estimated standard errors to reflect sampling error and between-study random variation. Then we evaluated the statistical significance of differences in behaviors across demographic categories and across behavioral measures. There were considerable differences in behaviors across demographic categories, possibly because of socioeconomic and cultural differences. For example, compared with women, men reported greater consumption of raw or undercooked foods, poorer hygiene, poorer practices to prevent cross-contamination, and less safe defrosting practices. Mid-age adults consumed more raw food (except milk) than did young adults and seniors. High-income individuals reported greater consumption of raw foods, less knowledge of hygiene, and poorer cross-contamination practices. The highest raw ground beef and egg consumption and the poorest hygiene and cross-contamination practices were found in the U.S. Mountain region. Meta-analysis was useful for identifying important data gaps and demographic groups with risky behaviors, and this information can be used to prioritize further research.     

In Vitro Evaluation of Rigosertib Antitumoral and Radiosensitizing Effects against Human Cholangiocarcinoma Cells

Cholangiocarcinoma is the first most common cancer of the biliary tract. To date, surgical resection is the only potentially curative option, but it is possible only for a limited percentage of patients, and in any case survival rate is quite low. Moreover, cholangiocarcinoma is often chemotherapy-resistant, and the only drug with a significant benefit for patient’s survival is Gemcitabine. It is necessary to find new drugs or combination therapies to treat nonresectable cholangiocarcinoma and improve the overall survival rate of patients. In this work, we evaluate in vitro the antitumoral effects of Rigosertib, a multi-kinase inhibitor in clinical development, against cholangiocarcinoma EGI-1 cell lines. Rigosertib impairs EGI-1 cell viability in a dose- and time-dependent manner, reversibility is dose-dependent, and significant morphological and nuclear alterations occur. Moreover, Rigosertib induces the arrest of the cell cycle in the G2/M phase, increases autophagy, and inhibits proteasome, cell migration, and invasion. Lastly, Rigosertib shows to be a stronger radiosensitizer than Gemcitabine and 5-Fluorouracil. In conclusion, Rigosertib could be a potential therapeutic option, alone or in combination with radiations, for nonresectable patients with cholangiocarcinoma.     

Validation of a method for simultaneous quantification of total carotenes and tocols in vegetable oils by HPLC

A normal-phase HPLC method for analysis of carotenes, tocopherols and tocotrienols has been developed and validated. In this work we presented a modification to the official AOCS method for analysis of tocols which allowed simultaneous quantification of the three groups of compounds, including carotenes. Analytes were separated using a gradient mobile phase (hexane and isopropanol) and with a gradient flow rate (1–2 mL min⁻¹). The column effluent was monitored by Photo Diode Array detector (PDA) set at 292 nm (tocols) and 455 nm (β-carotene) and by fluorescence detector set at an excitation wavelength of 290 and 330 nm emission. Inter- and intra-run accuracies and precision of the analytical method were better than ±15%. The lower limit of quantification was 5.0 mg L⁻¹ for the tocols and 0.1 mg L⁻¹ for carotenes. The method has been applied for the quantification of these compounds in Amazon oils.