The selection of efficient corrosion inhibitors requires detailed knowledge regarding the interaction mechanism, which depends on the type and amount of functional groups within the inhibitor molecule. The position of functional groups between different isomers is often overlooked, but is no less important, since factors like steric hinderance may significantly affect the adsorption mechanism. In this study, we have presented how different dihydroxybenzene isomers interact with aluminum alloy 5754 surface, reducing its corrosion rate in bicarbonate buffer (pH = 11). We show that the highest inhibition efficiency among tested compounds belongs to catechol at 10 mM concentration, although the differences were moderate. Utilization of novel impedance approach to adsorption isotherm determination made it possible to confirm that while resorcinol chemisorbs on aluminum surface, catechol and quinol follows the ligand exchange model of adsorption. Unlike catechol and quinol, the protection mechanism of resorcinol is bound to interaction with insoluble aluminum corrosion products layer and was only found efficient at concentration of 100 mM (98.7%). The aforementioned studies were confirmed with Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy analyses. There is a significant increase in the corrosion resistance offered by catechol at 10 mM after 24 h exposure in electrolyte: from 63 to 98%, with only negligible changes in inhibitor efficiency observed for resorcinol at the same time. However, in the case of resorcinol a change in electrolyte color was observed. We have revealed that the differentiating factor is the keto-enol tautomerism. The Nuclear Magnetic Resonance (NMR) studies of resorcinol indicate the keto form in structure in presence of NaOH, while the chemical structure of catechol does not change significantly in alkaline environment.

Electrochemical sensors have attracted increasing interest due to their low cost, high sensitivity of detected analytes, and the possibility of sensor miniaturization, which allows for portable and field applications. These devices provide information about the system composition in real-time by combining a chemically selective layer with an electrochemical transducer. Thereby, the chemical energy of the specific interaction between the chemical substances and the sensor is converted into an analytically useful signal. Herein we demonstrate the electrochemical sensor based on boron-doped diamond/graphene nanowall electrodes (B:DGNW). A B:DGNW electrode is a hybrid electrode, which combines the extraordinary features of boron-doped diamond and a graphene nanowall on the same surface. B:DGNW is a sp² -rich phase material with multilayered graphene walls oriented vertically to the substrate. Moreover, the presence of the boron-doped diamond phase enhances the electrochemical performance and kinetics of the electrode surface when compared with typical carbon nanowalls. The electrodes were fabricated in a one-step growth process using chemical vapor deposition without any additional modifications (thin films were grown on (100)-oriented silicon substrates). Two different sensing platforms will be presented: i) impedimetric biosensor for detection of pathogenic bacteria (e.g., Haemophilus influenzae), and ii) voltammetric sensor for determination of important nitroaromatic explosive compounds (2,4,6-trinitrotoluene (TNT), 2,4,6-trinitroanisole (TNA), 4,4',5,5'-tetranitro-1H,1'H-2,2'-biimidazole (TNBI)). The proposed B:DGNW electrodes were revealed to have a high electroactive area towards the voltammetric detection of various nitroaromatic compounds. The biosensor platform was obtained by B:DGNW surface functionalization firstly by electrografting of diazonium salt and secondly by the attachment of antibodies. The electrochemical biosensor shows high sensitivity and selectivity towards Haemophilus influenzae. The measurements were conducted in the presence of three non-target pathogens S. pyogenes, S. pneumoniae, and B. parapertussis. The proposed B:DGNW nonmodified carbon electrodes were revealed to have a high electroactive area towards the voltammetric determination of various nitroaromatic compounds, thus appearing to be an attractive nanocarbon surface for further applications. The B:DGNW electrode exhibits high sensing performance for TNT detection with linearity between 0.05 to 2 ppm and 4 to 15 ppm, and a limit of detection (LOD) of 73 ppb. The LOD for 2,4,6-trinitroanisole, in turn, is equal to 0.27 ppm, whereas the limit of detection of TNBI is equal to 0.52 ppm. To the authors' knowledge, this is the first time B:DGNW has been used to detect the nitroaromatic compounds electrochemically [1]. Acknowledgment This work was supported by the Science for Peace Programme of NATO [Grant no. G5147], Polish National Science Centre [2016/22/E/ST7/00102], and the National Centre for Science and Development [347324/12/NCBR/2017]. The DS funds of the Faculty of Electronics, Telecommunications, and Informatics of the Gdansk University of Technology are also acknowledged. Reference: [1] A. Dettlaff et al., J. Hazard. Mater [In press]. Doi: 10.1016/j.jhazmat.2019.121672.

Haemophilus influenzae (HI) is a Gram-negative pathogenic bacterium whose infections occur worldwide and mainly affect unvaccinated children and those who have not completed the basic vaccination course. Type B of this bacterium (Hib) can cause sepsis, and other invasive diseases as dermatitis or arthritis but the most dangerous is pneumonia meningitis. The most reliable method for recognizing Hib infections is isolation in microbiological culture. Serological tests are also performed to diagnose Hib infections. They rely on the detection of the presence of bacterial antigens or antibodies which have the ability to bind to specific antigens. Detection of antibodies doesn’t mean disease but only indicate contact with a given bacterium in the past. Recognition of bacteria using presently known methods takes a long time and requires expensive equipment although fast and sensitive detection of Haemophilus influenzae is crucial l to start treatment early enough. In this work, we present electrochemical detection of HI on diamond-based pastes electrodes using binding specific antibodies (ap. D) with proteins occurring on the surface of bacteria (protein D). The measuring system consisted of a specially prepared printed circuit board (PCB) and diamond-based electrode, which was prepared by screen printing in special conditions. Places printed on it, served as a working electrode, counter electrode and reference. Ceramics was first used as a substrate, but it was quickly changed to Teflon, which showed better adhesion to diamond pastes. Better sample strength was also obtained, so it could be washed in an ultrasonic cleaner without fear of damage. Before detection, the electrode had to be modified by electrochemical reduction of the aminobenzoic acid diazonium salt, antibodies deposition via EDC / NHS and blocking the unmodified electrode sites by incubating in solution of Bovine Serum Albumin (BSA). The last step of modification prevents unspecific adsorption on electrode surface which would lead to false detection results. Electrochemical Impedance Spectroscopy Fig. 1) were used to bacteria detection. The electron transfer resistance rises with each step of electrode modification and increased bacterial concentration in solution. Then a calibration curve was constructed. Three pathogens were selected to check the biosensor selectivity: S. pyogenes, S. pneumoniae, B. parapertussis. For each pathogen responses were significantly lower than for HI at similar concentrations. For example, the response of sensor for S. pyogenes (67474,28 CFU/ml) and B. parapertussis (17819,27 CFU/ml) were less than 5%, which are much smaller in comparison to response at level of 30% for HI (47003,48 CFU/ml). Acknowledgments The authors gratefully acknowledge financial support from the National Centre for Science and Development Grant Techmatstrateg No. 347324 2015/16/T/ST7/00469. Figure 1