A Novel Label-Free Optical Biosensor Using Synthetic Oligonucleotides from E. coli O157:H7: Elementary Sensitivity Tests

SiO2-TiO2 thin films for use as fiber optic guiding layers of optical DNA biosensors were fabricated by the sol-gel dip coating technique. The chemical structure and the surface morphology of the films were characterized before immobilization. Single probe DNA strands were immobilized on the surface and the porosity of the films before the hybridization process was measured. Refractive index values of the films were measured using a Metricon 2010 prism coupler. On the surface of each film, 12 different spots were taken for measurement and calculation of the mean refractive index values with their standard deviations. The increased refractive index values after the immobilization of single DNA strands indicated that immobilization was successfully achieved. A further refractive index increase after the hybridization with target single DNA strands showed the possibility of detection of the E. coli O157:H7 EDL933 species using strands of 20-mers (5′-TAATATCGGTTGCGGAGGTG -3′) sequence

Influence of the pore size on optical and mechanical properties of ecoflex sponges

Silicone polymers have various applications such as sensors, energy harvesters, soft robotics, prosthetics and implants. Ecoflex has become one of the most remarkable silicone polymers due to its special mechanical properties which include extreme stretchability and biocompatibility. In recent years, interest in porous silicone elastomers has increased in order to improve the absorption, flexibility and chemical activity of the material by increasing the surface area. In this study, porous Ecoflex 00-30 silicone elastomer material was prepared by using the low-cost sugar molding technique and its mechanical, optical and surface properties were investigated. In addition, we report on the influence of pore size on these properties of Ecoflex. Our results demonstrate that the Ecoflex material, which has a porous structure, has a more flexible structure. We have observed that the Ecoflex’s stretchability increased with pore size, especially in the 420–850 μ m range

Alterations in antioxidant enzyme activities and proline content in pea leaves under long-term drought stress

The effects of long-term drought stress on chlorophyll, proline, protein and hydrogen peroxide (H2O2) contents, malondialdehyde (MDA) in terms of lipid peroxidation and on the changes in the activities of antioxidant enzymes such as superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.1 1.1.6) and peroxidase (POX; EC 1.11.1.7) in the leaves of pea (Pisum sativum L.) were studied in field conditions. Chlorophyll and protein contents in leaves decreased significantly with increased drought stress. The proline content increased markedly under water deficit. MDA amounts were elevated as a result of water shortage, whereas H2O2 content changed slightly in pea leaves exposed to drought stress. Drought stress markedly enhanced the activities of SOD, CAT and PDX but slightly changed the activity of APX. We conclude that in field conditions, long-term water shortage increased the susceptibility to drought in peas

Effects of long-term salt stress on antioxidant system, chlorophyll and proline contents in pea leaves

The effects of long-term salt stress on the contents of chlorophyll, proline, protein, hydrogen peroxide (H2O2), and malondialdehyde (MDA) in terms of lipid peroxidation, and on the changes in activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) in leaves of pea (Pisum sativum cv Rona) were investigated in field conditions. Salinity and irrigation water regime experiments were set up in pots as randomized plot experimental designs with five replications. The experiment focused on pea responses to irrigation water salinity by irrigating the crops using 6 different levels of saline water (0.7, 2.0, 3.0, 4.0, 5.0 and 7.0 dS m(-1)) with a constant leaching fraction (LF = 0.30). The pots were located in the experimental area under a polyethylene cover which was about 1.8 m height from the surface for the purpose of eliminating rainfall effect on the experiments. Chlorophyll and protein contents were significantly decreased while accumulation of proline was enhanced with increased electrical conductivity (EC). Both MDA and H2O2 contents were reduced in the result of high salts application. All of the salt treatments increased total SOD activity significantly, as a remarkable increase in POD activity was observed especially at 5.0 and 7.0 dS/m EC. CAT and APX activities generally decreased in salt stressed seedlings. Our study indicates that its acquisition of salt tolerance may be a consequence of improved resistance to oxidative stress via increased activities of peroxidase and the superoxide dismutase/ascorbate-glutathione cycle

Exploration of carbon based solid acid catalyst derived from corn starch for conversion of non-edible oil into biodiesel

To avoid the problems caused by free fatty acids in the conversion of low cost vegetable oils to biodiesel, the use of solid acid catalyst for (trans-) esterification reaction is considered. Such a catalyst could be produced eco-friendly by using renewable raw materials such as biomass. The use of starch for this purpose it still very limited. In this paper, various methods were explored to produce a solid acid catalyst from corn starch. We investigated two different carbonization methods: complete pyrolysis in an oxygen-free environment and hydrothermal carbonization at milder conditions. Starch was used either in the native form or as pregelatinized starch. After the carbonization, acidic sites were introduced by sulfonating the materials. To characterize the catalysts, Scanning Electron Microscopy (SEM) was applied while the sulfonic content was determined by Energy Dispersive X-ray Spectroscopy (EDS). To test the performance of the catalysts, the conversion of free fatty acids was determined using oleic acid as a representative component of biodiesel feedstock. By both of the carbonization methods, a catalyst can be obtained that shows up to 84 % conversion of oleic acid. The hydrothermal treatment may then be preferred since it can be done at milder conditions. Differences between the performances of the respective catalyst samples could be well explained by structural features seen in the SEM-pictures. These also have their effect on the amount of sulfonic groups that was found (from EDS). The general trend is logical: the catalysts with a higher sulfonic load give a higher conversion of oleic acid

The effect of tocilizumab, anakinra and prednisolone on antibody response to SARS-CoV-2 in patients with COVID-19: A prospective cohort study with multivariate analysis of factors affecting the antibody response

Objectives: Disease severity, previous medications and immunosuppressive agents could affect the antibody response against SARS-CoV-2. This study aimed to analyze variables affecting the humoral response to SARS-CoV-2