Search

A range of both sol-gel and polymer derived sensor films have been developed for optical oxygen and pH sensing. Oxygen sensing is based on the luminescence quenching of the ruthenium complex [Ru(II)-tris( 4,7-diphenyl-l,10-plenanthroline)]dichloride, ([Ru(dpp)3]2+), which is entrapped in the sol-gel matrix. The oxygen-dependent luminescence is detected using the principle of phase fluorometry, which facilitates indirect monitoring of the luminescence lifetime. The pH sensor uses excitation ratiometric detection of the fluorescence from the pH sensitive dye, 1-hydroxypyrene-3,6,8-trisulfonic acid, ion-paired with cetyl trimethyl ammonium bromide (HPTS_IP). The phase-based detection scheme, dual lifetime referencing (DLR), was also examined as an alternative sensing strategy. ORMOSIL oxygen sensor films were fabricated using a range of organosilicon precursors including methyltriethoxysilane (MTEOS), ethyltriethoxysilane (ETEOS), n-propyltriethoxysilane (PTEOS) and phenyltriethoxysilane (PhTEOS). In addition to optimising the sensor performance, issues such as the influence of humidity on oxygen sensing were addressed. By varying the processing parameters, the surface characteristics and microstructure were tailored to suit applications such as breath gas analysis and bioprocess monitoring. pH sensor films were prepared by hydrolyzing and co-condensing (3-aminopropyl) trimethoxysilane (APTMS) with an organosilicon monomer such as ETEOS or PTEOS or the polymer, ethyl cellulose (EC). Optimised pH sensors showed good reproducibility, reversibility and short response times. The dynamic range for these sensor films extends from pH 6.00 to 8.50 which is relevant for bioprocess monitoring applications. The spectral compatibility of the luminophores and the printability of the sol-gels present the possibility of simultaneous oxygen and pH sensing using low-cost LEDs as excitation sources along with common detection electronics. [ABSTRACT FROM AUTHOR]

In this letter, we report a simple optical strategy designed to significantly enhance the fluorescence collection efficiency of planar substrate-based optical sensors. The strategy involves the use of refractive and reflective optical elements that permit supercritical angle fluorescence to be transmitted through the lower surface of the planar substrate and redirected toward an optical detector. Importantly, this approach facilitates simple integration with existing multianalyte sensor systems and microfluidic platforms by leaving the sensor's upper planar surface unstructured. In comparison to a conventional planar substrate configuration, the proposed approach can provide better than an order of magnitude (factor of 20) enhancement in the fluorescence intensity detected. It is envisaged that this approach will have significant potential in a range of application areas where there is need for low-cost optical sensor technologies. [ABSTRACT FROM PUBLISHER]

In this letter, we report on the development of a novel camera phone-based UV-dosimeter for monitoring the solar disinfection (SODIS) of water. The dosimeter consists of a UV indicator, methylene blue, dispersed in an ethylcellulose-based polymer matrix. To provide quantitative measurement of UV dose, we demonstrate the use of a camera phone to analyze dosimeter color change in response to UV exposure. The dosimeter response exhibits excellent agreement with a polynomial model (R2) >; 0.99) over the UV exposure range tested. A notable advantage of the dosimeter described here is that it can be deposited on a variety of substrates with the potential to be incorporated into water containers. It is envisaged that use of such a dosimeter in conjunction with mobile phone technology will enhance the use of SODIS thereby impacting significantly on the challenge of providing clean drinking water in developing regions of the world. [ABSTRACT FROM PUBLISHER]

Abstract: In this work we report on the so-called plasmonic enhancement effect, whereby the presence of metallic surfaces or particles in the vicinity of a fluorophore can dramatically alter the fluorescence emission and absorption properties of a fluorophore. The effect, which is associated with the surface plasmon resonance of the metallic surface, depends on parameters such as metal type, particle size, fluorophore type, and fluorophore-particle separation. This work focuses on the creation of metal nanoparticle arrays by a lithographic process and on optimisation strategies to maximise the fluorescence enhancement of dyes in the vicinity of the nanoparticles, for important applications such as fluorescence-based biochip platforms. Ordered arrays of metallic nano-islands were fabricated on glass substrates by a process of natural lithography using monodisperse polystyrene nanospheres. The metal particle dimensions were tailored in order to tune the plasmon resonance wavelength to match the spectral absorption of the fluorophore. The fluorophore, Cy5 dye, which is widely used in optical immunoassays and has a medium quantum efficiency (∼0.3), was used in this preliminary study of the plasmonic enhancement effect. The morphology of the metallic arrays was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Absorption and emission spectroscopies were used to elucidate the enhancement effect and its dependence on metal island morphology. Results were correlated with existing theoretical models. The applicability of this important technique to sensor platforms, such as fluorescence-based biochips, is also discussed. [Copyright &y& Elsevier]

Biopolymer-based packaging films were prepared from pectin (PEC) and sodium alginate (SA), with the incorporation of 10 % MCC and different concentrations of geraniol (GER at 2.5, 5.0, 7.5, and 10.0 %). Rheological properties suggested that film-forming solutions and film-forming emulsions exhibited a shear-thinning or pseudo-plastic non-Newtonian behaviour. The dried films were crosslinked with 2.0 % CaCl 2 . The addition of MCC into PEC/SA film enhanced the TS but reduced it with the impregnation of GER without influencing the EAB and toughness of the film. The water solubility of the films significantly reduced with the rise in the GER levels but enhanced the water vapor and oxygen barrier attributes. TGA demonstrated that incorporating MCC reduced the film's thermal degradation (44.92 % to 28.81 %), but GER had an insignificant influence on the thermal stability. FTIR spectra revealed that hydrogen bond formation was positively linked with the GER addition in the film formulation. X-ray diffractograms showed that prepared films were predominantly amorphous. Antimicrobial studies showed a complete reduction of Escherichia coli and Bacillus cereus in 24 h. Overall, the composite film displayed excellent physical and active properties and PEC/SA/MCC/5.0 %GER/CaCl 2 film was considered the best formulation for food packaging applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The present work investigated the structure-function relationship of dry fractionated oat flour (DFOF) as a techno-functional ingredient using bread as a model system. Mechanically, DFOF fractions (F), that is, F1: <224 µm, F2: 250-280 µm, F3: 280-500 µm, F4: 500-600 µm, and whole oat flour (F5) were blended with white wheat flour at 10%, 30%, and 50% substitution levels for bread making. The blended flours, doughs, and bread samples were assessed for their techno-functional, nutritional, and structural characteristics. The results of Mixolab and the Rapid Visco Analyzer show that the 50% substituted F3 fraction exhibits the highest water absorption properties (69.53%), whereas the 50% F1 fraction exhibits the highest peak viscosity of the past slurry. Analysis of bread samples revealed a lower particle size of DFOF fractions and higher supplementation levels, increased β-glucan levels (0.13-1.29 g/100 bread (db), reduced fermentable monosaccharides, that is, glucose (1.44-0.33 g/100 g), and fructose (1.06-0.28 g/100 g). The effect of particle size surpassed the substitution level effect on bread volume reduction. The lowest hardness value for F1 is 10%, and the highest value for F2 is 50%. The total number of cells in the bread slice decreased from the control to the F4 fraction (50%). Multi-criteria analysis indicated that DFOF fractions produced breads with similar structure and higher nutritional value developed from white wheat flour. PRACTICAL APPLICATION: The use of mechanically fractionated oat flours fractions in white wheat flour breads can improve the nutritional profile without affecting the physical properties of the bread product. Based on the oat flour fractions, bakers and food processing companies can tailor the bread formulations for high β-glucan, high fiber, and low reduced sugar claims., (© 2024 The Authors. Journal of Food Science published by Wiley Periodicals LLC on behalf of Institute of Food Technologists.)

The market has observed a rapid increase in the demand for plant-based foods as an alternative to animal meat products. Technologies such as high-moisture extrusion (HME) have the potential to develop anisotropic structures using alternative protein ingredients. This article discusses the different possible mechanisms responsible for structure formation and the effect of extrusion process parameters and outlines the recent advances in the long cooling dies (LCDs) used for meat alternative development. The role of different protein ingredients and the impact of combining them with other biopolymers were also evaluated. The underlying mechanism behind anisotropic structure formation during HME is a synergistic effect, with substantial dependence on the source of ingredients and their processing background. Formulation including proteins derived from plants, insects, animals, and microalgae with other biopolymers could pave the way to develop structured meat alternatives and fill nutritional interstices. Dynamic or rotating annular gap cooling dies operating at freely controllable shear and static annular gap dies are recent developments and assist to produce layered or fibrous structures. The complex chemical sites created during the HME of plant protein favour flavour and colour retention. This paper summarises the recent information published in the scientific literature and patents, which could further help researchers to fill the present knowledge gaps.

Suitable packaging material in combination with high-pressure processing (HPP) can retain nutritional and organoleptic qualities besides extending the product's shelf life of food products. However, the selection of appropriate packaging materials suitable for HPP is tremendously important because harsh environments like high pressure and high temperature during the processing can result in deviation in the visual and functional properties of the packaging materials. Traditionally, fossil-based plastic packaging is preferred for the HPP of food products, but these materials are of serious concern to the environment. Therefore, bio-based packaging systems are proposed to be a promising alternative to fossil-based plastic packaging. Some studies have scrutinized the impact of HPP on the functional properties of biopolymer-based packaging materials. This review summarizes the HPP application on biopolymer-based film-forming solutions and pre-formed biopolymer-based films. The impact of HPP on the key packaging properties such as structural, mechanical, thermal, and barrier properties in addition to the migration of additives from the packaging material into food products were systemically analyzed. HPP can be applied either to the film-forming solution or preformed packages. Structural, mechanical, hydrophobic, barrier, and thermal characteristics of the films are enhanced when the film-forming solution is exposed to HPP overcoming the shortcomings of the native biopolymers-based film. Also, biopolymer-based packaging mostly PLA based when exposed to HPP at low temperature showed no significant deviation in packaging properties indicating the suitability of their applications. HPP may induce the migration of packaging additives and thus should be thoroughly studied. Overall, HPP can be one way to enhance the properties of biopolymer-based films and can also be used for packaging food materials intended for HPP.

Background: Many adolescents meeting diagnostic criteria for social anxiety disorder (SAD) do not seek help or access timely professional supports. The current study investigated two hypothesized barriers to adolescents' seeking help for SAD: stigma and SAD symptoms., Method: Three hundred fifteen adolescents (52% female; mean age = 14.85 years) read a vignette describing a hypothetical peer with symptoms of SAD and completed measures of their own help-seeking intentions, SAD symptoms, stigma awareness and agreement., Results: The majority of adolescents reported that the vignette character needed help. Adolescents with more SAD symptoms, and those with greater stigma awareness, were less likely to indicate they would seek help from an adult they know (e.g., parent or teacher) for similar symptoms., Conclusions: Both SAD symptoms and perceptions of societal stigma may act as barriers to help-seeking for young people indicating the importance of intervention with young people, and the adults with whom they interact regularly., (© 2021 The Authors. Early Intervention in Psychiatry published by John Wiley & Sons Australia, Ltd.)