This paper presents an overview of semiconductor materials used in gas sensors, their technology, design, and application. Semiconductor materials include metal oxides, conducting polymers, carbon ...nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH
, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing. This overview covers the most used semiconducting materials in gas sensing, their synthesis methods and morphology, especially oxide nanostructures, heterostructures, and 2D materials, as well as sensor technology and design, application in advance electronic circuits and systems, and research challenges from the perspective of emerging technologies.
Biosensors need to meet the rising food industry demand for sensitive, selective, safe, and fast food safety quality control. Disposable colorimetric sensors based on gold nanoparticles (AuNPs) and ...localized surface plasmon resonance are low‐cost and easy‐to‐perform devices intended for rapid point‐of‐need measurements. Recent studies demonstrate various facile and versatile AuNPs‐based analytical platforms for the detection of bacteria and their toxins in milk, meat, and other foods. In this review, we introduce the general characteristics and mechanisms of AuNPs calorimetric biosensors, and highlight optimizations needed to strengthen and improve the quality of devices for their application in food matrices.
Copolymeric hydrogels of poly(N-isopropylmethacrylamide-co-N-isopropylacrylamide), p(NIPMAM/NIPAM), are synthesized by radical polymerization of N-isopropylmethacryl-amide (NIPMAM) and ...N-isopropylacrylamide (NIPAM) monomers by using the cross-linker ethylen glycol dimethacrylate (EGDM). The synthesized copolymeric p(NIPMAM/NIPAM) hydrogels, starting monomers and the cross-linker were structurally characterized by using Fourier transform infrared spectroscopy (FTIR). The amounts of residual reactants in the synthesized hydrogels were determined by high-pressure liquid chromatography (HPLC). Swelling of p(NIPMAM/NIPAM) hydrogels was investigated in relation to the temperature and pH value of the solution. The obtained values of residual monomer quantities are within acceptable limits and in the range from 2.69 to 5.25 mg g-1 for NIPMAM and 14.55 to 30.80 mg g-1 for NIPAM. The synthesized p(NIPMAM/NIPAM) hydrogels are negatively thermosensitive. The most common mechanisms of transport of a swelling solution in p(NIPMAM/NIPAM) hydrogels are polymer chain relaxation, (Case III), and the anomalous type of diffusion (non-Fickian diffusion). The maximal equilibrium swelling degree of 51.19 was reached by the p(NIPMAM/NIPAM) hydrogel with 1.5 mol% of EGDM at the temperature of 25?C and pH 4, whereas the lowest one of 0.98 was exhibited by the hydrogel with 3 mol% of EGDM at the temperature of 80?C and pH 7. Due to their low content of residual reactants and a satisfactory degree of swelling at various pH values, synthesized p(NIPMAM/NIPAM) hydrogels can be applied as carriers for the controlled release of pharmaceutically active substances.
nema
This paper explores the current and future potential of higher education for sustainable development in the Republic of Serbia drawing upon years of engagement in national sustainable development ...strategic planning and monitoring activities. Paper is structured as follows: first part is assessing the current developments in theory and practice of higher education for sustainable development, and possible implications on Serbian higher education practice. Following that, the criteria for the assessment of current situation in Serbian higher education space, including weakness and possibilities, are developed in the second part. Criteria are developed based on Copernicus charter. Conclusions and recommendations are drafted in the third part, based on the assessment results.
The paper argues that it is appropriate and desirable to accelerate the efforts on internal integration of Serbian Universities, as a precondition for further activities on the introduction of sustainability. Besides that, public sector and academic community must quest for innovative way of connection between higher education institutions and the community, predominantly through modernization of curricula and new research agenda. Education of educators for sustainable development may be the starting point for further steps in Serbia.
Ni-based catalysts supported on ceramics are particularly suitable for industrial applications, for instance reforming of hydrocarbons to produce synthesis gas or hydrogen and production of carbon ...nanofibers. Conventional synthesis processes for all metal/ceramic catalysts are impregnation, precipitation, co-precipitation and others. The authors have previously developed a novel process for the synthesis of Ni-based catalysts supported on reticulated ceramic foams, including impregnation of foams with ultrasonically generated aerosols of dissolved metal chlorides. By using appropriate multi-criteria analysis methods, the authors concluded that the novel process for the synthesis of Ni-based catalysts was superior in terms of economic and technological aspects. The aim of this research was to compare the novel synthesis processes for a Ni-Pd/Al2O3 catalyst and for other Ni-based catalysts by performing life cycle assessment and evaluating the environmental impacts of each synthesis process. Characterisation results showed that the dominant environmental impact results from production of palladium (II) chloride for the Ni-Pd/Al2O3 catalyst synthesis process, while the other catalyst synthesis process had large environmental impacts associated with high energy consumption. The final outcome, obtained from comparison of normalisation results, indicates that the novel Ni-Pd/Al2O3 catalyst synthesis process had the smallest environmental impact.
•Assessment of Ni-based catalyst synthesis processes impacts on the environment.•Large environmental impacts can be associated with the consumption of electricity.•Other significant environmental impact comes from use of palladium II chloride.•Compared to other, the novel catalyst synthesis process had small environmental impact.•Significant environmental impacts can be avoided if cleaner production of electricity is used.
This article elaborates the characteristics of knowledge management in the context of occupational safety and presents the results of research based on the assumption that there is a link between ...knowledge management and occupational safety performance, and that knowledge management can help in improving occupational safety performance. The research involved 645 occupational safety experts from three Balkan countries (Slovenia, Croatia and Serbia). The results showed that the knowledge management in the organization is related to all of the observed aspects of occupational safety performance: number of work-related injuries within the organization; number of lost working days due to injuries; costs caused by work-related injuries and occupational diseases; financial investments in occupational safety; assessment of the state of occupational safety. The practical implications of the article can be seen in the context of meeting the educational needs for continuous learning and improvement of knowledge/lifelong learning in the field of occupational safety.
Purpose: The aim of the paper was to develop the simple procedures for preparation of inclusion complexes of ellagic acid (EA) with cyclodextrins (CDs) and to investigate their antioxidant and ...antimicrobial activity.
Methods: The structural characterization was carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) methods. The phase solubility technique was used to investigate the interactions between 'host' and 'guest' molecules and to estimate the molar ratio between them. The antioxidant and antimicrobial activity of EA and inclusion complexes were determined.
Results: The apparent stability constants were found to be 117 dm
3
mol
−1
for the complex with β-CD and 161 dm
3
mol
−1
for the complex with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD). The results of phase-solubility studies showed that EA formed the inclusion complexes with CDs in the molar ratio of 1:1. The calculated half-maximal inhibitory concentration was 41.18 μg cm
−3
for butyl hydroxy toluene, 1.96 μg cm
−3
for EA, 0.88 μg cm
−3
for inclusion complex with HP-β-CD, and 1.27 μg cm
−3
for inclusion complex with β-CD.
Conclusion: The stability constants indicated the rapid release of EA from the inclusion complexes in the aqueous medium at 25 °C. The antioxidant activity of EA was increased, while the antimicrobial activity was preserved after complexation with CDs.
This work aimed to evaluate chemical profile, antioxidant activity and topical application safety of the raw Osage orange (
(Raf.) Schneid) fruit extracts obtained by maceration using ethanol and ...acetone. Out of eighteen different compounds registered in the extracts, fifteen were identified by ultra-high-performance liquid chromatography-tandem mass spectrometry. Pomiferin and osajin were characteristic and representative compounds in both ethanolic and acetone extracts of the Osage orange fruit. Both extracts showed good antioxidant activity (EC
= 0.03 mg/cm
) after 20 min of incubation. The topical administration safety of the extracts was evaluated
by measuring skin biophysical parameters: electrical capacitance and erythema index, as indicators of
hydration and irritation, respectively. Based on the results of the
skin tests, it can be concluded that both of the Osage orange fruit extracts are safe for topical administration - they increased skin hydration and reduced skin irritation under the occlusion.
A simple sol-gel method and external gelatinization method of hollow alumina spheres synthesis were developed in this study. The spheres were modified with polyethyleneimine (PEI) producing PEI-Al
2
...O
3
via (3-glycidyloxypropyl)trimethoxy-silane, GLYMO, linker. Characterization results, obtained using XRD and SEM microscopy revealed spherical geometry with a hollow core of PEI-Al
2
O
3
adsorbent. Introduction of a large number of the amino group, 6.9 mmol g
−1
, contributes to achieving high adsorption capacities,
q
m
, of 95.6, 124.9, 61.3, and 125.9 mg g
−1
for Cd
2+
, Pb
2+
, As(V), and DCF, respectively, which is obtained by using the Langmuir model. Thermodynamic studies indicated feasible adsorption and higher spontaneity with temperature increase. The kinetic study conveniently modeled using pseudo-second-order (PSO) and Weber-Morris kinetic model, as well as single resistance mass transfer model, indicated a change of the contribution of diffusional processes during adsorption with a dominance of intra-particle diffusion. The fixed-bed column adsorption data, fitted using Bohart-Adams, Clark, Yoon-Nelson, and Thomas models, showed lower capacity in comparison to batch study, and thus clear potential applicability of PEI-Al
2
O
3
was deduced even at a high loading of feed water.