Search Results (27)

The stability of cement slurries under high-temperature conditions poses a significant engineering challenge in cementing operations. This study explored the development of a novel tetrameric thermosensitive thickening polymer (TTSTC) as a solution to this problem. Aqueous free radical polymerization was employed to synthesize the polymer. The base monomers 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylamide (AM) were employed, in conjunction with the long-chain thermosensitive monomers octadecyldimethylallylammonium chloride (C18DMAAC) and N-vinylpyrrolidone (NVP). The optimal synthesis conditions were determined by orthogonal experiments as follows: monomer molar ratio (AM:AMPS:C18DMAAC:NVP) = 15:10:5:5, initiator concentration of 16 wt%, cross-linker concentration of 0.45 wt%, pH 6, and polymerization temperature of 60 °C. The chemical structure of TTSTC was characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR), gel permeation chromatography, scanning electron microscopy, Zeta potential, and particle size measurement. The results verified the successful synthesis of the target polymer. Its thermal stability, thermosensitive thickening behavior, and salinity resistance were systematically investigated. Furthermore, the impact of TTSTC on the settling stability, rheological characteristics, and compressive strength of cement paste was assessed. The experimental findings demonstrated that TTSTC displayed noteworthy thermosensitive thickening properties at temperatures up to 279 °C, pH values ranging from 11 to 13, and NaCl/CaCl₂ concentrations between 0.05 and 0.5 g/L. The optimal performance of TTSTC was observed at mass fractions ranging from 0.6 to 0.8 wt%. When incorporated into the slurry at 0.6–1.0 wt%, TTSTC significantly improved the slurry settling stability, thickening properties, and 28d compressive strength at elevated temperatures compared with the control. When comparing the temperature-sensitive thickening performance of the newly developed treatment agent with that of the commercially available xanthan gum thickener, the results showed that for the cement slurry system containing the new treatment agent at a mass fraction of 0.6%, the reduction in consistency was 30.9% less than that of the cement slurry system with xanthan gum at a mass fraction of 0.6%. These findings indicate that TTSTC has the potential to function as a highly effective additive in cementing operations conducted in extreme environments, thereby enhancing the stability and dependability of such operations. Full article

Coenzyme Q₁₀ (CoQ₁₀) is a molecule that serves as a coenzyme for mitochondrial enzymes, playing a fundamental role in mitochondrial bioenergetics as an electron and proton carrier in the energy production process. This study aimed to examine the modulatory effects of moderate/high-intensity exercise and CoQ₁₀ supplementation on tumstatin, lipid dynamics, and body mass in rats. This study used 42 male Wistar Albino rats in six groups: a control group (C), a moderate-intensity continuous training group (MICT), a high-intensity continuous training group (HICT), a coenzyme Q₁₀ group (Q₁₀), a moderate-intensity continuous training combined with Q₁₀ group (MICTQ₁₀), and a high-intensity continuous training combined with Q₁₀ group (HICTQ₁₀) to assess the effects of exercise and 5 mg/kg/daily CoQ₁₀ supplementation. Rats underwent treadmill training, and tumstatin levels in plasma, cardiac, and skeletal muscle tissues were measured using ELISA and immunostaining techniques. In addition to the plasma, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and total cholesterol (TC) levels were analyzed using enzymatic methods, with the LDL-C calculated using the Friedewald equation. The atherogenic index of plasma was determined by the TG/HDL-C ratio. As compared to group C, body mass was significantly affected by both exercise intensity and supplementation (p = 0.01, η² = 0.37), with the MICTQ₁₀ and HICTQ₁₀ groups demonstrating the greatest reductions by day 50th (p = 0.0003, d = 4.02; p = 0.0001, d = 3.99). Lipid profiles varied significantly between groups. Compared to the C group, the MICTQ₁₀ group exhibited the most substantial decreases in LDL-C (p = 0.03, d = 2.35) and TG levels (p = 0.03, d = 2.25), while the HICTQ₁₀ group showed the most pronounced reduction in TC levels (p = 0.001, d = 6.41). Regarding tumstatin levels, skeletal muscle tumstatin levels were lowest in the HICTQ₁₀ group (p = 0.01, d = 2.11). Moreover, cardiac muscle tumstatin levels were significantly lower in the MICTQ₁₀, MICT, and HICTQ₁₀ groups compared to in the C group (p = 0.004, d = 1.01). These findings suggest that both exercise intensity and CoQ₁₀ supplementation exert notable physiological effects, particularly in modulating body mass, lipid metabolism, and tumstatin levels. Full article

Acidic oxygen evolution reaction (OER) electrocatalysts that provide high activity, lower costs, and long-term stability are needed for the wide-scale adoption of proton-exchange membrane (PEM) water electrolyzers for generating hydrogen through electrochemical water splitting. We report the effects of chromium substitution and temperature treatments on the structure, OER activity, and electrochemical stability of ruthenium oxide (RuO₂) aerogel OER electrocatalysts. RuO₂ and Cr-substituted RuO₂ aerogels (Ru_0.6Cr_0.4O₂) were synthesized using sol–gel chemistry and then thermally treated at different temperatures. Introducing chromium into the synthesis increased the surface area (7–11 times higher) and pore volume (5–6 times higher) relative to RuO₂ aerogels. X-ray diffraction analysis is consistent with s that Cr was substituted into the rutile RuO₂ structure. X-ray photoelectron spectroscopy showed that trivalent Cr substitution altered the surface electronic structure and ratio of surface hydroxides. The specific capacitance values of Cr-substituted RuO₂ aerogels were consistent with charge storage within a hydrous surface. Cr-substituted RuO₂ aerogels exhibited 26 times the OER mass activity and 3.5 times the OER specific activity of RuO₂ aerogels. Electrochemical stability tests show that Cr-substituted RuO₂ aerogels exhibit similar stability to commercial RuO₂. Understanding how metal substituents can be used to alter OER activity and stability furthers our ability to obtain highly active, durable, and lower-cost OER electrocatalysts for PEM electrolyzers. Full article

The study presents findings on the relative humidity (R.H.) sensing capabilities of a resistive sensor. This sensor utilizes sensing layers composed of a ternary nanohybrid, consisting of holey carbon nanohorn (CNHox), potassium chloride (KCl), and polyvinylpyrrolidone (PVP), with mass ratios of 7/1/2, 6.5/1.5/2, and 6/2/2 (w/w/w). The sensing structure comprises a silicon substrate, a SiO₂ layer, and interdigitated transducer (IDT) electrodes. The sensing film is deposited on the sensing structure via the drop-casting method. The sensing layers’ morphology and composition are investigated through Scanning Electron Microscopy (SEM) and RAMAN spectroscopy. The resistance of thin-film sensors based on ternary hybrids increased with exposure to a range of relative humidity (R.H.) levels, from 0% to 100%. The newly designed devices demonstrated a comparable response at room temperature to that of commercial capacitive R.H. sensors, boasting excellent linearity, swift response times, and heightened sensitivity. Notably, the studied sensors outperform others employing CNHox-based sensing layers in terms of sensitivity, as observed through manufacturing and testing processes. It elucidates the sensing mechanisms of each constituent within the ternary hybrid nanocomposites, delving into their chemical and physical properties, electronic characteristics, and affinity for water molecules. Various alternative sensing mechanisms are considered and discussed, including the reduction in holes within CNHox upon interaction with water molecules, proton conduction, and PVP swelling. Full article

Proton exchange membrane water electrolysis is hindered by the sluggish kinetics of the anodic oxygen evolution reaction. RuO₂ is regarded as a promising alternative to IrO₂ for the anode catalyst of proton exchange membrane water electrolyzers due to its superior activity and relatively lower cost compared to IrO₂. However, the dissolution of Ru induced by its overoxidation under acidic oxygen evolution reaction (OER) conditions greatly hinders its durability. Herein, we developed a strategy for stabilizing RuO₂ in acidic OER by the incorporation of high-valence metals with suitable ionic electronegativity. A molten salt method was employed to synthesize a series of high-valence metal-substituted RuO₂ with large specific surface areas. The experimental results revealed that a high content of surface Ru⁴⁺ species promoted the OER intrinsic activity of high-valence doped RuO₂. It was found that there was a linear relationship between the ratio of surface Ru⁴⁺/Ru³⁺ species and the ionic electronegativity of the dopant metals. By regulating the ratio of surface Ru⁴⁺/Ru³⁺ species, incorporating Re, with the highest ionic electronegativity, endowed Re_0.1Ru_0.9O₂ with exceptional OER activity, exhibiting a low overpotential of 199 mV to reach 10 mA cm⁻². More importantly, Re_0.1Ru_0.9O₂ demonstrated outstanding stability at both 10 mA cm⁻² (over 300 h) and 100 mA cm⁻² (over 25 h). The characterization of post-stability Re_0.1Ru_0.9O₂ revealed that Re promoted electron transfer to Ru, serving as an electron reservoir to mitigate excessive oxidation of Ru sites during the OER process and thus enhancing OER stability. We conclude that Re, with the highest ionic electronegativity, attracted a mass of electrons from Ru in the pre-catalyst and replenished electrons to Ru under the operating potential. This work spotlights an effective strategy for stabilizing cost-effective Ru-based catalysts for acidic OER. Full article

Significant advances in Penning trap measurements of atomic masses and mass ratios of the proton, deuteron, triton, helion, and alpha-particle have occurred in the last five years. These include a measurement of the mass of the deuteron against ¹²C with 8.5 × 10⁻¹² fractional uncertainty; resolution of vibrational levels of H₂⁺ as mass and the application of a simultaneous measurement technique to the H₂⁺/D⁺ cyclotron frequency ratio, yielding a deuteron/proton mass ratio at 5 × 10⁻¹²; new measurements of HD⁺/³He⁺, HD⁺/T⁺, and T⁺/³He⁺ leading to a tritium beta-decay Q-value with an uncertainty of 22 meV, and atomic masses of the helion and triton at 13 × 10⁻¹²; and a new measurement of the mass of the alpha-particle against ¹²C at 12 × 10⁻¹². Some of these results are in strong disagreement with previous values in the literature. Their impact in determining a precise proton/electron mass ratio and electron atomic mass from spectroscopy of the HD⁺ molecular ion is also discussed. Full article

Background: Mitochondrial dysfunction is a risk factor in the pathogenesis of metabolic disorders. According to the energy requirements, oxidative phosphorylation and the electron transport chain work together to produce ATP in sufficient quantities in the mitochondria of eukaryotic cells. Abnormal mitochondrial activity causes fat accumulation and insulin resistance as cells require a balance between the production of ATP by oxidative phosphorylation (OXPHOS) in the mitochondria and the dissipation of the proton gradient to reduce damage from reactive oxygen species (ROS). This study aims to explore the relationship between the mitochondrial content of sperm and the ratio of mitochondrial DNA to nuclear DNA in relation to body mass index (BMI) and how it may affect the progressive motility of sperm cell. Understanding the relationships between these important variables will help us better understand the possible mechanisms that could connect sperm motility and quality to BMI, as well as further our understanding of male fertility and reproductive health. Methods: Data were collected from 100 men who underwent IVF/ICSI at the University Hospital of Ioannina’s IVF Unit in the Obstetrics and Gynecology Department. The body mass index (BMI) of the males tested was used to classify them as normal weight; overweight; and obese. Evaluations included sperm morphology; sperm count; sperm motility; and participant history. Results: In the group of men with normal BMI, both BMI and progressive motility displayed a statistically significant association (p < 0.05) with mitochondrial DNA content, relative mitochondrial DNA copy number, and the mtDNA/nDNA ratio. Similar to this, there was a positive association between BMI and motility in the groups of men who were overweight and obese, as well as between the expression of mitochondrial DNA and the mtDNA/nDNA ratio, with statistically significant differences (p < 0.05). There was not a statistically significant difference observed in the association between the relative mtDNA copy number and BMI or motility for the overweight group. Finally, the relative mtDNA copy number in the obese group was only associated with motility (p = 0.034) and not with BMI (p = 0.24). Conclusions: We found that in all three groups, BMI and progressive motility exhibited comparable relationships with mitochondrial DNA expression and the mtDNA/nDNA ratio. However, only in the normal group and in the obese group, the relative mitochondrial DNA copy number showed a positive association with BMI and progressive motility. Full article

Impulsive solar energetic-particle (SEP) events were first distinguished as the streaming electrons that produce type III radio bursts as distinct from shock-induced type II bursts. They were then observed as the surprisingly enhanced ³He-rich SEP events, which were also found to have element enhancements rising smoothly with the mass-to-charge ratio A/Q through the elements, even up to Pb. These impulsive SEPs have been found to originate during magnetic reconnection in solar jets where open magnetic field lines allow energetic particles to escape. In contrast, impulsive solar flares are produced when similar reconnection involves closed field lines where energetic ions are trapped on closed loops and dissipate their energy as X-rays, γ-rays, and heat. Abundance enhancements that are power laws in A/Q can be used to determine Q values and hence the coronal source temperature in the events. Results show no evidence of heating, implying reconnection and ion acceleration occur early, rapidly, and at low density. Proton and He excesses that contribute their own power law may identify events with reacceleration of SEPs by shock waves driven by accompanying fast, narrow coronal mass ejections (CMEs) in many of the stronger jets. Full article

Concerns about the impact of space radiation on spacecraft and their internal instruments have prompted the need for effective protection. However, excessive protection can increase the costs and difficulty of space launches, making it crucial to achieve better shielding protection of lighter weights. In real space orbits, we observed the interference of charged particles on photon-counting imaging detectors and plan to address this issue by adding a shielding ring to the side wall of the detector input terminal. Additionally, a local protection structure was proposed for electronics, where the outer edge was increased to enable particles to reach the same thickness as the shielding box within the PCB range. This approach resulted in an omnidirectional spatial shielding thickness that was nearly identical at any point on the PCB surface. Furthermore, we used the Monte Carlo method to calculate the energy loss of electrons and protons in materials such as aluminum (Al), tantalum (Ta), and high-density polyethylene (HDPE). Through this analysis, we determined the optimal mass ratio of Al, Ta, and HDPE to achieve the lowest ionization doses at an object’s location in the particle environment of the FY-3 satellite orbit. This protection strategy provides a useful design concept for photoelectric detection instruments with high sensitivity. Full article

Flavonoids are biologically active natural products of great interest for their potential applications in functional foods and pharmaceuticals. A hesperetin-7-O-glucoside inclusion complex with β-cyclodextrin (HEPT7G/βCD; SunActive^® HCD) was formulated via the controlled enzymatic hydrolysis of hesperidin with naringinase enzyme. The conversion rate was nearly 98%, estimated using high-performance liquid chromatography analysis. The objective of this study was to investigate the stability, solubility, and spectroscopic features of the HEPT7G/βCD inclusion complex using Fourier-transform infrared (FTIR), Raman, ultraviolet–visible absorption (UV–vis), ¹H- and ¹³C- nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), liquid chromatography/mass spectroscopy (LC–MS), scanning electron microscopy (SEM), and powdered X-ray diffraction (PXRD) spectroscopic techniques including zeta potential, Job’s plot, and phase solubility measurements. The effects of complexation on the profiles of supramolecular interactions in analytic features, especially the chemical shifts of β-CD protons in the presence of the HEPT7G moiety, were evaluated. The stoichiometric ratio, stability, and solubility constants (binding affinity) describe the extent of complexation of a soluble complex in 1:1 stoichiometry that exhibits a greater affinity and fits better into the β-CD inner cavity. The NMR spectroscopy results identified two different configurations of the HEPT7G moiety and revealed that the HEPT7G/βCD inclusion complex has both –2S and –2R stereoisomers of hesperetin-7-O-glucoside possibly in the –2S/–2R epimeric ratio of 1/1.43 (i.e., –2S: 41.1% and –2R: 58.9%). The study indicated that encapsulation of the HEPT7G moiety in β-CD is complete inclusion, wherein both ends of HEPT7G are included in the β-CD inner hydrophobic cavity. The results showed that the water solubility and thermal stability of HEPT7G were apparently increased in the inclusion complex with β-CD. This could potentially lead to increased bioavailability of HEPT7G and enhanced health benefits of this flavonoid. Full article

The hydrolysis of aluminum (Al) is a promising method for on-demand hydrogen generation for low-power proton exchange membrane fuel cell (PEMFC) applications. In this study, Al composites were mechanochemically activated using bismuth (Bi) and nickel (Ni) as activation compounds. The main objective was to determine the effects of Bi and Ni on Al particles during mechanochemical processing, and the hydrolysis activity of the Al-Bi-Ni composites. Successfully formulated ternary Al-Bi-Ni composites were hydrolyzed with de-ionized water under standard ambient conditions to determine the reactivity of the composite (extent of hydrogen production). Scanning electron microscopy (SEM) showed that Bi and Ni were distributed relatively uniformly throughout the Al particles, resulting in numerous micro-galvanic interactions between the anodic Al and cathodic Bi/Ni during hydrolysis reaction. The addition of >1 wt% Ni resulted in incomplete activation of Al, and such composites were non-reactive. All successfully prepared composites had near-complete hydrogen yields. X-ray diffraction (XRD) showed that no mineralogical interaction occurred between Al, Bi, and/or Ni. The main phases detected were Al, Bi, and minute traces of Ni (ascribed to low Ni content). In addition, the effect of the mass ratio (mass Al:mass water) and water quality were also determined. Full article

The efficient isolation process and understanding of lignin properties are essential to determine key features and insights for more effective lignin valorization as a renewable feedstock for the production of bio-based chemicals including wood adhesives. This study successfully used dilute acid precipitation to recover lignin from black liquor (BL) through a single-step and ethanol-fractionated-step, with a lignin recovery of ~35% and ~16%, respectively. The physical characteristics of lignin, i.e., its morphological structure, were evaluated by scanning electron microscopy (SEM). The chemical properties of the isolated lignin were characterized using comprehensive analytical techniques such as chemical composition, solubility test, morphological structure, Fourier-transform infrared spectroscopy (FTIR), ¹H and ¹³C Nuclear Magnetic Resonance (NMR), elucidation structure by pyrolysis-gas chromatography-mass spectroscopy (Py-GCMS), and gel permeation chromatography (GPC). The fingerprint analysis by FTIR detected the unique peaks corresponding to lignin, such as C=C and C-O in aromatic rings, but no significant differences in the fingerprint result between both lignin. The ¹H and ¹³C NMR showed unique signals related to functional groups in lignin molecules such as methoxy, aromatic protons, aldehyde, and carboxylic acid. The lower insoluble acid content of lignin derived from fractionated-step (69.94%) than single-step (77.45%) correlated to lignin yield, total phenolic content, solubility, thermal stability, and molecular distribution. It contradicted the syringyl/guaiacyl (S/G) units’ ratio where ethanol fractionation slightly increased syringyl unit content, increasing the S/G ratio. Hence, the fractionation step affected more rupture and pores on the lignin morphological surface than the ethanol-fractionated step. The interrelationships between these chemical and physicochemical as well as different isolation methods were investigated. The results obtained could enhance the wider industrial application of lignin in manufacturing wood-based composites with improved properties and lower environmental impact. Full article

Electromagnetic form factors are fundamental quantities describing the internal structure of hadrons. They can be measured with scattering processes in the space-like region and annihilation processes in the time-like region. The two regions are connected by crossing symmetry. The measurements of the proton electromagnetic form factors in the time-like region using the initial state radiation technique are reviewed. Recent experimental studies have shown that initial state radiation processes at high luminosity electron-positron colliders can be effectively used to probe the electromagnetic structure of hadrons. The BABAR experiment at the B-factory PEP-II in Stanford and the BESIII experiment at BEPCII (an electron positron collider in the $\tau$-charm mass region) in Beijing have measured the time-like form factors of the proton using the initial state radiation process $e^{+}{e}^{-}\to p\overline{p}\gamma$. The two kinematical regions where the photon is emitted from the initial state at small and large polar angles have been investigated. In the first case, the photon is in the region not covered by the detector acceptance and is not detected. The Born cross section and the proton effective form factor have been measured over a wide and continuous range of the the momentum transfer squared $q^2$ from the threshold up to 42 (GeV/c)${}^2$. The ratio of electric and magnetic form factors of the proton has been also determined. In this report, the theoretical aspect and the experimental studies of the initial state radiation process $e^{+}{e}^{-}\to p\overline{p}\gamma$ are described. The measurements of the Born cross section and the proton form factors obtained in these analyses near the threshold region and in the relatively large $q^2$ region are examined. The experimental results are compared to the predictions from theory and models. Their impact on our understanding of the nucleon structure is discussed. Full article

An overview of recent progress on testing Lorentz and CPT symmetry using Penning traps is presented. The theory of quantum electrodynamics with Lorentz-violating operators of mass dimensions up to six is summarized. Dominant shifts in the cyclotron and anomaly frequencies of the confined particles and antiparticles due to Lorentz and CPT violation are derived. Existing results of the comparisons of charge-to-mass ratios and magnetic moments involving protons, antiprotons, electrons, and positrons are used to constrain various coefficients for Lorentz violation. Full article

In this paper, we present the relative humidity (RH) sensing response of a chemiresistive sensor, employing sensing layers based on a ternary nanohybrids comprised of holey carbon nanohorns (CNHox), titanium (IV) oxide, and polyvinylpyrrolidone (PVP) at 1/1/1/(T1), 2/1/1/(T2), and with 3/1/1 (T3) mass ratios. The sensing device is comprised of a silicon-based substrate, a SiO₂ layer, and interdigitated transducer (IDT) electrodes. The sensitive layer was deposited via the drop-casting method on the sensing structure, followed by a two-step annealing process. The structure and composition of the sensing films were investigated through scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). The resistance of the ternary nanohybrid-based sensing layer increases when H increases between 0% and 80%. A different behavior of the sensitive layers is registered when the humidity increases from 80% to 100%. Thus, the resistance of the T1 sensor slightly decreases with increasing humidity, while the resistance of sensors T2 and T3 register an increase in resistance with increasing humidity. The T2 and T3 sensors demonstrate a good linearity for the entire (0–100%) RH range, while for T1, the linear behavior is limited to the 0–80% range. Their overall room temperature response is comparable to a commercial humidity sensor, characterized by a good sensitivity, a rapid response, and fast recovery times. The functional role for each of the components of the ternary CNHox/TiO₂/PVP nanohybrid is explained by considering issues such as their electronic properties, affinity for water molecules, and internal pore accessibility. The decreasing number of holes in the carbonaceous component at the interaction with water molecules, with the protonic conduction (Grotthus mechanism), and with swelling were analyzed to evaluate the sensing mechanism. The hard–soft acid-base (HSAB) theory also has proven to be a valuable tool for understanding the complex interaction of the ternary nanohybrid with moisture. Full article