Case study of a driven pile foundation in diatomaceous soil. II: Pile installation,dynamic analysis,and pore pressure generation

This paper presents the results from a case study highlighting the difficulties of pile driving in diatomaceous soils.In the companion(first)paper to this article,results of an extensive laboratory and in situ testing program were presented while the results from pile driving and further analysis of field observations were presented herein.Unexpected high pile rebound(HPR)was observed during driving of a closed-end pipe pile,with refusal occurring at a depth of less than 5 m.Subsequent open-ended piles were thus driven.Piezometer and case pile wave analysis program(CAPWAP)data were collected during driving of both closed-and open-end piles.Piezometer data indicated that negative pore water pressures(PWPs)were generated while the closed-ended pile exhibited high rebound.Results from in situ tests indicated change in material stiffness and strong dilative tendencies near the depth of refusal.A hypothesis for observed behavior was proposed that considers the soil beneath the pile as a medium with an effectively infinite bulk modulus.     

Synthesis of hexagonal cobalt hydroxide and cobalt oxide nanorings as promising materials for oxygen evolution and supercapacitive processes

Preparing the low-cost nanomaterials for electrocatalytic processes is still a big challenge. Mesoporous cobalt hydroxide and cobalt oxide nanoparticles were prepared through simple soft chemistry as high-performance materials for durable electrocatalyst for OER and supercapacitive applications. The synthesis method is used to prepare nanoring particles in neither emulsion nor template-directed method. The final nanoparticles display mesoporous hexagonal nanoring morphology. The physio-chemical properties of the as-synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption-desorption techniques. The TEM characterizations prove that NPs retain the topotactical relationship in their structure during the conversion process. The BET measurements prove the mesoporous nature of the nanorings, having good specific surface area and pore volume. Finally, the electrochemical performance toward water splitting and supercapacitor applications were investigated by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and cyclic voltammetry (CV) techniques. The Co₃O₄ NPs exhibits better catalytic properties than Co(OH)₂ NPs when applied as electrocatalyst in an alkaline medium for water splitting and supercapacitor measurements. The enhanced electrocatalytic performance attributed to the mesoporous structure along with high pore volume, which provides more active boundary sites for the electrochemical process, resulted in the enhanced exchange of the intermediates and more efficient electron transfer. This synthetic methodology, with the advantages of inexpensive/non-complicated experimental setup and high electrochemical performance, could shed light on the development of non-expensive electrocatalysts for clean energy production and storage.     

Enhancement of Biodiesel Production from Chicken Fat Using MgO and MgO@Na2O Nanocatalysts

Biodiesel was produced from chicken fat in the presence of MgO and MgO@Na₂O nanocatalysts via transesterification. The characteristics of MgO and MgO@Na₂O were examined using various analyses, including BET specific surface areas, energy‐dispersive X‐ray spectroscopy/mapping scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy. The maximum yields of biodiesel production using MgO and MgO@Na₂O nano‐catalysts were 95.17 and 95.22 %, respectively, which are significant biodiesel yields. ¹H NMR analysis was used to determine the molecular structure of the chicken fat oil and the produced biodiesel. Furthermore, the reusability of the catalysts was examined for up to six steps, showing that both catalysts can be used for up to four steps in biodiesel production.     

Effects of 211 and 413 ordering on the corrosion behavior of V-Al-C MAX phases prepared by spark plasma sintering

In the present study, two V-Al-C based MAX phases, i.e., V₂AlC and V₄AlC₃ having two types of ordering were successfully manufactured by spark plasma sintering and the corrosion behavior of sintered samples was evaluated. Al, V and C metal powders were mixed with the desired molar ratios by a mixer mill, and sintered at 1300 °C. The relative density calculation revealed almost full densification for both prepared MAX phases. The measurements of mechanical properties showed a low increase in bending strength and Vickers hardness of V₄AlC₃ compared to V₂AlC MAX phase. Evaluation of corrosion behavior of developed MAX phases was carried out in 6.5 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. Corrosion current density and corrosion potential of V₂AlC (5.3 ± 0.21 μA/cm² and -0.451 ± 0.01 V, respectively), and V₄AlC₃ (1.07 ± 0.22 μA/cm² and -0.091 ± 0.02 V, respectively) were measured and no passivation behavior was observed in their potentiodynamic polarization curves. However, EIS tests at open circuit potential confirmed more corrosion resistance of V₄AlC₃compared to V₂AlC. These tests also revealed the active dissolution of MAX phases in 6.5 M HCl solution at anodic potential of +0.1 V, while the impedance values of V₄AlC₃ were larger than those of V₂AlC. Microstructural investigation revealed the preferential dissolution of V₂AlC phase in grain boundaries after corrosion test. Moreover, the layered structure of V₂C MXenes was observed in some regions. After corrosion test, V₄C₃ MXene layers had larger thickness compared to V₂AlC. It was found that V₄AlC₃ with higher amount of Al₂O₃ and thicker layers has more corrosion resistance than V₂AlC MAX phase.     

Characterization of the HCN Interaction Partner TRIP8b/PEX5R in the Intracardiac Nervous System of TRIP8b-Deficient and Wild-Type Mice

The tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b/PEX5R) is an interaction partner and auxiliary subunit of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are key for rhythm generation in the brain and in the heart. Since TRIP8b is expressed in central neurons but not in cardiomyocytes, the TRIP8b-HCN interaction has been studied intensely in the brain, but is deemed irrelevant in the cardiac conduction system. Still, to date, TRIP8b has not been studied in the intrinsic cardiac nervous system (ICNS), a neuronal network located within epicardial fat pads. In vitro electrophysiological studies revealed that TRIP8b-deficient mouse hearts exhibit increased atrial refractory and atrioventricular nodal refractory periods, compared to hearts of wild-type littermates. Meanwhile, heart rate, sino-nodal recovery time, and ventricular refractory period did not differ between genotypes. Trip8b mRNA was detected in the ICNS by quantitative polymerase chain reaction. RNAscope in situ hybridization confirmed Trip8b localization in neuronal somata and nerve fibers. Additionally, we found a very low amount of mRNAs in the sinus node and atrioventricular node, most likely attributable to the delicate fibers innervating the conduction system. In contrast, TRIP8b protein was not detectable. Our data suggest that TRIP8b in the ICNS may play a role in the modulation of atrial electrophysiology beyond HCN-mediated sino-nodal control of the heart.     

Polyvinyl alcohol – Zedo gum edible film: Physical,mechanical and thermal properties

The effects of different percentages of Zedo gum (ZG) (10, 20, and 30 w/w%) on the properties of polyvinyl alcohol (PVA) films by casting method were investigated in this study. Physical, thermal, optical as well as mechanical properties of neat PVA, PVA/ZG and neat ZG films were also characterized. All blend PVA/ZG films produced homogeneous, flexible and transparent films, while neat ZG could not form flexible films and films were opaque. Moreover, Fourier transform infrared (FTIR) spectroscopy and thermal behavior confirmed the formation of hydrogen bonds and subsequently compatibility of the two polymers. In general, reduced moisture content, water solubility and water vapor permeability (WVP) were obtained in the blend films rather than the neat PVA films. However, this reduction tended to increase with a rise in the amount of ZG. Furthermore, films with higher ZG concentration (30%) showed lower mechanical strength than the other blend films but were stronger than neat PVA films. However, low water vapor permeability, high mechanical properties and thermal resistance made this edible film appropriate for packaging different food and non-food applications.