Search

A silicon oxynitride channel waveguide based evanescent-field optical transducer is presented for lab-on-chip application. The optical biosensor detects luminescent bioanalytes infiltrated within a reactor well realized across the waveguide. As a main novelty, the sensing mechanism proposed makes use of the evanescent-field propagating in the waveguide to both excite and to collect the fluorescent signal. To understand the chip behavior, its design and collection efficiency were analyzed by finite-difference time-domain simulations in comparison with similar structures differing in the bioreactor thickness and therefore in the excitation and collection mechanisms. It is demonstrated that the best efficiency and performance are reached for the proposed dual evanescent field approach. Characterization of the optical losses and fluorescence measurements from a dye solution infiltrated in the bioreactor well validate the proposed working concept. [ABSTRACT FROM AUTHOR]

Abstract: We report on the α-sexithiophene sub-monolayer growth with supersonic molecular beam deposition by investigating how the kinetic energy of the impinging molecules influences the growth on substrates with different surface wettabilities and temperatures. The results show that the energy of the impinging molecules affects the morphology of the molecular film increasing the coverage and the island size, and reducing the fractality of the sub-monolayer islands. The possibility of directing growth of more ordered islands could improve the performances of electronic devices, which are greatly affected by the structure of the first monolayers. [Copyright &y& Elsevier]

Aims: The objective of this work was to investigate the lipase production by a newly isolated Penicillium sp ., using experimental design technique, in submerged fermentation using a medium based on peptone, yeast extract, NaCl and olive oil, as well as to characterize the crude enzymatic extracts obtained. Methods and Results: Lipase activity values of 9·5 U ml−1 in 96 h of fermentation was obtained at the maximized operational conditions of peptone, yeast extract, NaCl and olive oil concentrations (g l−1) of 20·0, 5·0, 5·0 and of 10·0 respectively. The partial characterization of crude enzymatic extract obtained by submerged fermentation showed optimum activity at pH range from 4·9 to 5·5 and temperature from 37°C to 42°C. The crude extract maintained its initial activity at freezing temperatures up to 100 days. Conclusions: A newly isolated strain of Penicillium sp . used in this work yielded good lipase activities compared to the literature. Significance and Impact of the Study: The growing interest in lipase production is related to the potential biotechnological applications that these enzymes present. New lipase producers are relevant to finding enzymes with different catalytic properties of commercial interest could be obtained, without using genetically modified organisms (GMO). [ABSTRACT FROM AUTHOR]

Ecological economics was formally established in 1989 with the ambitious vision of developing a new economic paradigm embedding the social and economic systems in the biophysical world. Ecological economics had its roots in the biophysical understanding of economics that pioneers of the field Georgescu-Roegen (1971), Odum (1971), Daly (1977), Jansson (1984), Martinez-Alier (1987) and others developed while studying the thermodynamic bedrocks shared by natural and social systems. Subsequently, however, ecological economics has explicitly but controversially adopted a 'big umbrella' approach to methodological pluralism, focusing more on topics such as valuing nature and its functions rather than attempting to understand and quantify the biophysical roots of economic activities. Biophysical economics was established in response to these concerns, focusing more on developing analyses and models of the transformations of nature to generate wealth and approached mostly from an energy and material flows perspective. The present paper argues that to achieve its original vision ecological economics must return to its biophysical roots. Collaboration between the two fields will help the next generation of thinkers to address the socio-ecological challenges of the 21st century requiring an energy transformation called for by aspirations such as the Green New Deal and the UN Sustainable Development Goals. • The biophysical foundation of socio-economic systems must be at the center of the research agenda of ecological economics. • The socio-ecological challenges of the 21st century are biophysical in nature and will require education, management and policy that is based more on these biophysical realities and principles. • Prioritizing these biophysical foundations is fundamental for the next energy transition. • If proper biophysical procedures (such as comprehensive energy analyses) are not undertaken no "sustainable" recommendations can be considered valid. [ABSTRACT FROM AUTHOR]

Abstract: We report on a new hybrid approach to realize optical slab waveguides for optical amplification purposes. The structure consists of a dye-doped polymer core (PMMA) deposited over an oxidized porous silicon (PS) cladding layer formed on a silicon wafer. The very low refractive index (n =1.16) achievable in the cladding allows obtaining monomodal behavior with high confinement factors (Γ TE =96%) even for very thin cores (400nm). Optically excited guided luminescence shows stimulated emission, strong line narrowing and a clear threshold and superlinear behavior with pump energy. By means of the variable stripe length (VSL) technique, values of net optical gain up to 113dB/cm (constant over 3mm) and absolute amplification values up to 34dB have been measured at 694nm when pumping with 80mJ/cm2 energy pulses. These results validate the use of oxidized PS as a cladding layer in silicon photonics. [Copyright &y& Elsevier]

To circumvent fluctuations in the dairy industry, freezing acid casein is a way to enhance autonomy in the production of quality dairy products. Thus, the aim of the present study was to evaluate frozen acid casein and its application in the production of processed cheese on an industrial scale considering the real logistics of a dairy product. Changes in protein were evidenced by relative casein, electropherograms and microstructure. Also, the melting time was longer for frozen acid casein to obtain the standard moisture content. The texture profile introduced increase in hardness with the increase in freezing time. Positive results were found for the b∗ colour parameter, tending the characteristic yellow colour of processed cheese. However, these changes were not observed in the chemical parameters of the processed cheese, indicating that frozen acid casein can be used to produce processed cheese with characteristics that meet industry standards. [ABSTRACT FROM AUTHOR]