Rapid Voltammetric Screening Method for the Assessment of Bioflavonoid Content Using the Disposable Bare Pencil Graphite Electrode

Hesperidin (HESP) is a plant bioflavonoid found in various nutritional and medicinal products. Many of its multiple health benefits rely on the compound’s antioxidant ability, which is due to the presence of oxidizable hydroxyl groups in its structure. Therefore, the present study aimed to investigate the electrochemical behavior of HESP at a cheap, disposable pencil graphite electrode (PGE) in order to develop rapid and simple voltammetric methods for its quantification. Cyclic voltammetric investigations emphasized a complex electrochemical behavior of HESP. The influence of the electrode material, solution stability, supporting electrolyte pH, and nature were examined. HESP main irreversible, diffusion-controlled oxidation signal obtained at H type PGE in Britton Robinson buffer pH 1.81 was exploited for the development of a differential pulse voltammetry (DPV) quantitative analysis method. The quasi-reversible, adsorption-controlled reduction peak was used for HESP quantification by differential pulse adsorptive stripping voltammetry (DPAdSV). The linear ranges of DPV and DPAdSV were 1.00 × 10−7–1.20 × 10−5 and 5.00 × 10−8–1.00 × 10−6 mol/L with detection limits of 8.58 × 10−8 and 1.90 × 10−8 mol/L HESP, respectively. The DPV method was applied for the assessment of dietary supplements bioflavonoid content, expressed as mg HESP.

Fe, N-Doped Metal Organic Framework Prepared by the Calcination of Iron Chelated Polyimines as the Cathode-Catalyst of Proton Exchange Membrane Fuel Cells

Aromatic polyimine (PIM) was prepared through condensation polymerization between p-phenylene diamine and terephthalaldehyde via Schiff reactions. PIM can be physically crosslinked with ferrous ions into gel. The gel-composites, calcined at two consecutive stages, with temperatures ranging from 600 to 1000 °C, became Fe- and N-doped carbonaceous organic frameworks (FeNC), which demonstrated both graphene- and carbon nanotube-like morphologies and behaved as an electron-conducting medium. After the two-stage calcination, one at 1000 °C in N2 and the other at 900 °C in a mixture of N2 and NH3, an FeNC composite (FeNC-1000A900) was obtained, which demonstrated a significant O2 reduction peak in its current–voltage curve in the O2 atmosphere, and thus, qualified as a catalyst for the oxygen reduction reaction. It also produced a higher reduction current than that of commercial Pt/C in a linear scanning voltage test, and the calculated e-transferred number reached 3.85. The max. power density reached 400 mW·cm−2 for the single cell using FeNC-1000A900 as the cathode catalyst, which was superior to other FeNC catalysts that were calcined at lower temperatures. The FeNC demonstrated only 10% loss of the reduction current at 1600 rpm after 1000 redox cycles, as compared to be 25% loss for the commercial Pt/C catalyst in the durability test.

Experimental Investigations and Numerical Simulations of the Vibrational Performance of Wood Truss Joist Floors with Strongbacks

This paper provides an experimental study and computer modeling analysis of vibration performance of full-scale wood truss joist floors, related to the static deflection and vibration mode/frequency and single-person-induced vibration. The vibration behavior of full-scale truss joist floors was investigated and the influences of the strongbacks on the vibration behavior were assessed. The results showed that the simulated predictions agreed well with the measured results. Strongbacks do not significantly affect the fundamental frequency of the truss joist floors but influence the second and third modal frequencies. The use of strongback rows at mid-span effectively decreased the maximum deformation of point loading at floor center. The effect of adding strongbacks at one-third of each span on decreasing maximum deformation at the floor center was minimal. The case of walking parallel to the joist produced higher acceleration response at the floor center than that of walking perpendicular to the joist. The closer the placements of strongbacks were to the mid-span, the more significant reduction of the vibration at floor center was. Two strongback rows at mid-span performed the best effect on reduction of vibration response at floor center. However, the use of strongbacks had limits of reduction peak acceleration of the sheathing between the joists. The study provides a valuable guide for future vibration serviceability study and design optimization of wood truss joist floors.

Reducing Furnace Operating Costs: IGBT/MFDC Technology Saves on Energy

Real power savings are observed in a case study comparing a VRT (Variable Reactance Transformer) and an IGBT/MFDC power supply in a furnace retrofit. The IGBT (Insulated Gate Bipolar Transistor) is the power controller and MFDC (Mid Frequency Direct Current) is the transformer portion of the power supply. The VRT was replaced with a similarly sized IGBT/MFDC power supply. Other variables remained essentially equivalent and provided a good comparison between the power consumption of a VRT versus an IGBT/MFDC system in an equivalent furnace. IGBT/MFDC offers cost savings through less kilowatt usage, lower peak demand, and better power factor when compared to other power controls. From this case study, we will demonstrate a 40 percent reduction in kilowatt consumption, a 14 percent reduction peak demand, and a high displacement power factor throughout the cycle. All of this results in lower costs for furnace operation.

Adaptable Resilience Assessment Framework to Evaluate an Impact of a Disruptive Event on Freight Operations

Freight transportation is a major economic backbone of the United States. Ports, as one of the primary components of freight transportation, have experienced significant growth and increased capacity during the past two decades. This study develops an adaptable resilience assessment framework that evaluates the impact of a disruptive event on transportation operations. The framework identifies dynamic performance levels over an extended period of an event including five distinct phases of responses: staging, reduction, peak, restoration, and overloading. This study applies the framework to the Port of Houston, Texas, during a major hurricane event, Harvey, and two holiday events in 2017. The framework evaluates proactive and reactive responses of port truck activities during the disruptions and provides a comprehensive assessment of resilience and adaptability in port truck operations. This study showed that a short proactive response before a disaster results in a long recovery period with over 250% increases in volume between a port terminal (Barbours Cut) to its regional destinations. Trucks serving local facilities show stable and shorter response phases, while regional operations maintain a prolonged staging or overloading phases to handle the excess demands especially for significant multi-day disruptive events. The economic analysis shows that the increased economic gain during a proactive or reactive stage could substantially alleviate the losses resulting from impaired port operations. Evaluating response systems and resilience of port truck activities during severe weather events represents the first step for designing plans that support a fast system recovery that minimizes the economic, social, and human impacts.

Local Structure and Redox Properties of Amorphous CeO2-TiO2 Prepared Using the H2O2-Modified Sol-Gel Method

Amorphous CeO2-TiO2 nanoparticles synthesized by the H2O2-modified sol-gel method were investigated in terms of the Ce-O-Ce and Ti-O-Ti linkage, local structure, and redox properties. The decrease in the crystallinity of CeO2-TiO2 by H2O2 addition was confirmed. The metal–oxygen linkage analysis showed the difference in size of the metal–oxygen network between crystalline CeO2-TiO2 and amorphous CeO2-TiO2 due to the O22− formed by H2O2. The local structure of CeO2-TiO2 was analyzed with an extended X-ray absorption fine structure (EXAFS), and the oscillation changes in the k space revealed the disordering of CeO2-TiO2. The decrease in Ce-O bond length and the Ce-O peak broadening was attributed to O22− interfering with the formation of the extended metal–oxygen network. The temperature-programmed reduction of the H2 profile of amorphous CeO2-TiO2 exhibited the disappearance of the bulk oxygen reduction peak and a low-temperature shift of the surface oxygen reduction peak. The H2 consumption increased compared to crystalline CeO2-TiO2, which indicated the improvement of redox properties by amorphization.

Expanding the Chemical Space of Benzimidazole Dicationic Ionic Liquids

Benzimidazole dicationic ionic liquids (BDILs) have not yet been widely explored in spite of their potential. Therefore, two structurally related families of BDILs, paired with either bromide or bistriflimide anions and bearing alkyl spacers ranging from C3 to C6, have been prepared. Their thermal properties have been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), while their electrical properties have been assessed by cyclic voltammetry (CV). TG analysis confirmed the higher stability of the bistriflimide BDILs over the bromide BDILs, with minor variation within the two families. Conversely, DSC and CV allowed for ascertaining the role played by the spacer length. In particular, the thermal behavior changed dramatically among the members of the bistriflimide family, and all three possible thermal behavior types of ILs were observed. Furthermore, cyclic voltammetry showed different electrochemical window (C3(C1BenzIm)2/2Tf2N < C4(C1BenzIm)2/2Tf2N, C5(C1BenzIm)2/2Tf2N < C6(C1BenzIm)2/2Tf2N) as well as a reduction peak potential, shape, and intensity as a function of the spacer length. The results obtained highlight the benefit of accessing a more structurally diverse pool of compounds offered by dicationic ILs when compared to the parent monocationic ILs. In particular, gains are to be found in the ease of fine-tuning their properties, which translates in facilitating further investigations toward BDILs as designer solvents and catalysts.

Separation of the overlapped vitamin B1 and B3 voltammetric peaks by means of Continuous Wavelet Transform and differentiation

Due to the indubitable role of vitamins in maintaining human health, a lot of attention has been paid to the methods and analytical procedures of their determination. Voltammetric methods are of particular interest as they do not involve complex sample preparation, however, close values of the redox potential of some vitamins may result in peak overlapping, hindering the quantitative analysis. This paper addresses the separation of overlapped reduction peak of vitamins B1 and B3 by means of Continuous Wavelet Transform (with appropriately selected mother wavelets) and differentiation of the recorded voltammograms. These numerical algorithms allowed to obtained linear, single-variable calibration functions that comply with the applied in analytical chemistry criteria regarding the correlation coefficients and the limit of detection and quantification. Their relatively simple implementation does not include any manual interpretation step; thus, these algorithms provide impartial and reproducible results. The proposed methodology has been applied in the determination of vitamins B1 and B3 in dietary supplements, providing results consistent with the declaration of the manufacturer. Graphic abstract

Effects of 99mTc on the electrochemical properties of thiamazole in vitro

Thiamazole inhibits the thyroid hormone synthesis and does not inactivate the existing thyroxine and triiodothyronine that circulate in the blood. In this paper Thiamazole electrochemical behavior was monitored by cyclic voltammetry on glassy carbon (GC) electrode in the absence and presence of sodium pertechnetate (99mTc). The influence of different Thiamazole concentrations without and in the presence of radiopharmaceutical 99mTc, the effect of the number of scan cycles, and the effect of 99mTc activity on the appearance of cyclic voltammograms were examined. The results show that there is an observed increase in the reduction peak current with an increase of Thiamazole concentration. It was found that the concentration of the tested drug had a significant effect on its redox characteristics. The results obtained show that the application of different concentrations of sodium pertechnetate exhibits the inhibitory properties of the used radiopharmaceutical on the drug in the treatment of thyroid gland disease.